tim penyusun - idu.ac.id

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TIM PENYUSUN

Penyadur : Sovian Aritonang

Editor : Ridho Illahi Putra

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KATA PENGANTAR

Puji syukur kehadirat Allah SWT atas limpahan rahmat dan

karunianya sehingga Buku Bahan Ajar MK. Military Platform Design Prodi

Teknologi Daya Gerak Fakultas Teknologi Pertahanan Universitas

Pertahanan telah dapat diselesaikan. Buku bahan ajar ini merupakan

penyempurnaan dari edisi sebelumnya, sebagai bahan ajar bagi

mahasiswa Program Studi Prodi Teknologi Daya Gerak Fakultas

Teknologi Pertahanan Universitas Pertahanan agar mahasiswa

mendapatkan gambaran secara jelas mengenai MK. Military Platform

Design.

Program Belajar Mengajar di Fakultas Teknologi Pertahanan

ditujukan untuk memenuhi prinsip-prinsip pokok yang terkandung dalam

Paradigma Baru Penataan Pendidikan Tinggi di Indonesia. Paradigma

baru tersebut meliputi 5 (lima) prinsip yaitu: kualitas, otonomi, akuntabilitas

/ pertanggungjawaban, akreditasi dan evaluasi. Selain lima prinsip

tersebut, maka aspek inovasi dan kreatifitas juga menjadi karakteristik

yang melekat dalam seluruh kegiatan mendukung Program Belajar

Mengajar.

Buku Bahan Ajar ini diharapkan dapat menjadi salah satu sumber

acuan yang dapat dipakai di dalam keseluruhan rangkaian aktivitas

Pembelajaran, evaluasi keberhasilan studi, Kuliah Kerja Dalam Negeri

(KKDN), Kuliah Kerja Luar Negeri (KKLN), tugas akhir, administrasi

perkuliahan dan kurikulum. Buku pedoman ini, wajib digunakan oleh

semua pihak yang berperan seperti dosen, mahasiswa, dan tenaga

kependidikan sehingga dapat terlaksana dengan efisien dan efektif.

Kepada semua pihak yang berkontribusi dalam penyusunan buku

bahan ajar ini, pimpinan fakultas menyampaikan terima kasih dan

penghargaan yang sebesar-besarnya.

Sesprodi

Teknologi Daya Gerak,

Dr. Sovian Aritonang, S.Si., M.Si

Kolonel Kes. NRP. 519726

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DAFTAR ISI

DAFTAR ISI ........................................................................................... i

KATA PENGANTAR ............................................................................... ii

DAFTAR ISI ............................................................................................ iii

PERTEMUAN 1 Operasional Environment.............................................. 1

1.1 Pendahuluan .......................................................................... 1

1.2 Tujuan Instruksional Umum .................................................... 1

1.3 Tujuan Instruksional Khusus................................................... 1

1.4 Skenario Pembelajaran .......................................................... 1

1.5 Ringkasan Materi ................................................................... 2

1.5.1 The Constants ...................................................... 2

1.5.2 Trends Influencing the World’s Security ................ 6

1.5.3 The Implications for the Joint Force War in the the

Twenty-First Century ............................................ 10

1.5.4 Preparing for War ................................................. 12

1.5.5 The Conduct of Military Operations in the Twenty

First Century ......................................................... 17

PERTEMUAN 2 Naval Ship Design ........................................................ 21

2.1 Pendahuluan .......................................................................... 21





2.5.1 History of Structural Design-Comercial VS Naval .. 22

2.5.2 Recent Trends in Naval Vessel Design ................. 27

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2.5.3 Naval Structural Design Philosophy ...................... 29

2.5.4 External Blast Events ............................................ 32

PERTEMUAN 3 Military and Commercial Shipbuilding ........................... 35

3.1 Pendahuluan .......................................................................... 35





3.5.1 Shipbuilding Trends .............................................. 35

3.5.2 Differences Between Military and Commercial

Shipbuilding .......................................................... 36

3.5.3 Prospects for Market Entry an Integration ............. 37

3.5.4 The Way Forward ................................................. 39

PERTEMUAN 4 Introduction to Aircraft Stability ..................................... 42

4.1 Pendahuluan .......................................................................... 42





4.5.1 Aerodynamic Controls .......................................... 42

4.5.2 Atmospheric Properties ......................................... 44

4.5.3 Aerodynamic Background ..................................... 44

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PERTEMUAN 5 Konsep Struktur Fighter ............................................... 49

5.1 Pendahuluan .......................................................................... 49





5.5.1 Struktur Analysis ................................................... 49

5.5.2 Structure & Payload Design .................................. 52

PERTEMUAN 6 Introdouction To Fighter ................................................ 59

6.1 Pendahuluan .......................................................................... 59





6.5.1 Kompetensi Dalam Pengembangan Pesawat

Terbang ................................................................ 60

6.5.2 Airplane Integration .............................................. 62

PERTEMUAN 7 Propulsion ................................................................... 68

7.1 Pendahuluan .......................................................................... 68





7.5.1 Propulsion analysis ............................................... 69

7.5.2 Propulsion Integration ........................................... 70

PERTEMUAN 8 UTS ............................................................................. 77

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PERTEMUAN 9 Structural, Design and Analysis ................................... 78

9.1 Pendahuluan .......................................................................... 78





9.5.1 State of the Art ...................................................... 78

9.5.2 Scope of the work ................................................. 86

9.5.3 Limitations ............................................................ 89

9.5.4 The method........................................................... 91

PERTEMUAN 10 Marine Propulsion ...................................................... 93

10.1 Pendahuluan ........................................................................ 93

10.2 Tujuan Instruksional Umum .................................................. 93

10.3 Tujuan Instruksional Khusus ................................................. 93

10.4 Skenario Pembelajaran ........................................................ 93

10.5 Ringkasan Materi ................................................................. 94

10.5.1 Propulsion Systems ............................................ 94

10.5.2 Matching Engines and Watercrafts ..................... 105

10.5.3 Wave resistance ................................................. 106

10.5.4 Submarines ........................................................ 108

PERTEMUAN 11 Avionics, Navigation, and Instrumention ..................... 112

11.1 Pendahuluan ........................................................................ 112





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11.5.1 Avionics System Patterned After Apollo;

Features and Capabilities Unlike Any Other

in the Industry .................................................... 112

11.5.2 Central Processor Units Were Available Off the

Shelf—Remaining Hardware and Software

Would Need to be Developed ............................. 115

PERTEMUAN 12 Jet Fighter Aircraft ..................................................... 124

12.1 Pendahuluan ........................................................................ 124





12.5.1 Jet fighter aircraft ................................................ 124

12.5.2 A Brief History of the Development of Jet Fighter

Aircraft ................................................................. 127

12.5.3 First Generation Jet Fighters ............................... 129

12.5.4 Second Generation Jet Fighters.......................... 130

12.5.5 Third Generation Jet Fighter ............................... 131

PERTEMUAN 13 Flotation, hydrostatics, and ship stability ..................... 133

13.1 Pendahuluan ........................................................................ 133





13.5.1 Flotation, hydrostatics, and ship stability ............ 133

13.5.2 Archimedes priciple ............................................ 135

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13.5.3 The gentle art of ballooning ................................. 137

13.5.4 Stability of Floating bodies .................................. 139

PERTEMUAN 14 Fundamentals of Systems Engineering....................... 145

14.1 Pendahuluan ........................................................................ 145





14.5.1 Design Solution Definition Process ..................... 145

14.5.2 Multidisclinary Design Optimization ..................... 148

14.5.4 Concurrent design approach ............................... 154

PERTEMUAN 15 Studi Kasus ............................................................... 159

PERTEMUAN 16 UAS ............................................................................ 160

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PERTEMUAN 1

Operasional Environment

1.1. Pendahuluan

Pokok bahasan materi dalam pertemuan 1 terdiri dari:

a. The Constants

b. Trends Influencing The World‘s Security

c. The Contextual World

d. The Implications for the Joint Force

e. Some Leading Questions

1.2. Tujuan Instruksional Umum

Setelah mempelajari pokok bahasan materi 1, mahasiswa mampu

memahami The Constants, Trends Influencing The World‘s

Security,The Contextual World,The Implications for the Joint Force,

Some Leading Questions

1.3. Tujuan Instruksional Khusus


menjelaskan The Constants, Trends Influencing The World‘s

Security,The Contextual World,The Implications for the Joint Force,

Some Leading Questions

1.4. Skenario Pembelajaran

a. Dosen menjelaskan silabus kuliah, aturan kuliah, dan sistem

penilaian

b. Dosen menjelaskan materi kuliah

c. Diskusi dan tanya jawab dengan mahasiswa

d. Pembagian kelompok

e. Evaluasi pencapaian belajar

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1.5. Ringkasan Materi:

1.5.1 The Constants

We cannot predict exactly what kind of war, or for what

purposes, the armed forces of the United States will find

themselves engaged in over the next quarter century. We can

only speculate about possible enemies and the weapons they

will bring to the fight. But we can state with certainty that the

fundamental nature of war will not change. In a democracy

such as the United States, political aims, pressures, and

hesitations have always conditioned military operations – and

will continue to do so. ―When whole communities go to war...

the reason always lies in some political situation.‖5 War is a

political act, begun for political purposes. In the twenty-first

century war will retain its political dimension, even when it

originates in the actions of non-state and transnational groups.

The Joint Force will operate in an international environment

where struggle predominates. While the origins of war may

rest on policy, a variety of factors has influenced the conduct

of that struggle in the past and will do so in the future. The

tension between rational political calculations of power on one

hand and secular or religious ideologies on the other,

combined with the impact of passion and chance, makes the

trajectory of any conflict difficult if not impossible to predict. In

coming decades, Americans must struggle to resist judging

the world as if it operated along the same principles and

values that drive our own country. In many parts of the world,

there are no rational actors, at least in our terms. Against

enemies capable of mobilizing large numbers of young men

and women to slaughter civilian populations with machetes or

to act as suicide bombers in open markets; enemies eager to

die, for radical ideological, religious, or ethnic fervor; enemies

who ignore national borders and remain unbound by the

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conventions of the developed world; there is little room for

negotiations or compromise. It can become a matter of

survival when human passion takes over. Such a world has

existed in recent history – in World War II on the Eastern Front

and on the islands of the Pacific, in Africa in the Rwandan

genocide, and to some extent in Iraq. In a world where

passions dominate, the execution of rational strategy becomes

extraordinarily difficult.

War more than any other human activity engages our

senses: at times providing a ―rush‖ of fear, horror, confusion,

rage, pain, helplessness, nauseous anticipation, and hyper-

awareness. It is in these vagaries that imponderables and

miscalculations accumulate to paralyze the minds of military

and political leaders. In the cauldron of war, ―It is the

exceptional [human being] who keeps his powers of quick

decision intact.

There are other aspects of human conflict that will not

change no matter what advances in technology or computing

power may occur: fog and friction will distort, cloak, and twist

the course of events. Fog will result from information overload,

our own misperceptions and faulty assumptions, and the fact

that the enemy will act in an unexpected fashion. Combined

with the fog of war will be its frictions - that almost infinite

number of seemingly insignificant incidents and actions that

can go wrong, the impact of chance, and the horrific effect of

combat on human perceptions. It will arise ―from fundamental

aspects of the human condition and unavoidable

unpredictabilities that lie at the very core of combat

processes.‖71

It is the constant fog and friction of war that turn the simple

into the complex. In combat, people make mistakes. They

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forget the basics. They become disoriented, ignoring the vital

to focus on the irrelevant. Occasionally, incompetence

prevails. Mistaken assumptions distort situational awareness.

Chance disrupts, distorts, and confuses the most careful of

plans. Uncertainty and unpredictability dominate. Thoughtful

military leaders have always recognized that reality, and no

amount of computing power will eradicate this basic

messiness.

Where friction prevails, tight tolerances, whether applied to

plans, actions, or materiel are an invitation to failure – the

more devastating for being unexpected. Operational or

logistical concepts or plans that make no allowance for the

inescapable uncertainties of war are suspect on their face –

an open invitation to failure and at times defeat.

Still another enduring feature of conflict lies in the recurring

fact that military leaders often fail to recognize their enemy as

a learning, adaptive force. War ―is not the action of a living

force upon a lifeless mass...

but always the collision of two living forces.‖8 Those living

forces possess all the cunning and intractable characteristics

human beings have enjoyed since the dawn of history.

Even where adversaries share a similar historical and

cultural background, the mere fact of belligerence guarantees

profound differences in attitudes, expectations, and behavioral

norms. Where different cultures come into conflict, the

likelihood that adversaries will act in mutually

incomprehensible ways is even more likely. Thus, ―if you know

the enemy and know yourself you need not fear the results of

a hundred battles.‖9 The conduct of war demands a deep

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understanding of the enemy – his culture, history, geography,

religious and ideological motivations, and particularly the huge

differences in his perceptions of the external world. The

fundamental nature of war will not change.

The Nature of Change

If war will remain a human endeavor, a conflict between two

learning and adapting forces, changes in the political

landscape, adaptations by the enemy, and advances in

technology will change the character of war. Leaders are often

late to recognize such changes. Driven by an inherent desire

to bring order to a disorderly, chaotic universe, human beings

tend to frame their thoughts about the future in terms of

continuities and extrapolations from the present and

occasionally the past. But a brief look at the past quarter

century, to say nothing of the past four thousand years,

suggests the extent of changes that coming decades will

bring. Twenty-five years ago the Cold War encompassed

every aspect of the American military‘s thinking and

preparation for conflict – from the strategic level to the tactical.

Today, that all-consuming preoccupation is an historical relic.

A quarter century ago, the United States confronted the Soviet

Union, a truculent, intractable opponent with leaders firmly

committed to the spread of Marxist-Leninist ideology and

expansion of their influence. At that time, few in the

intelligence communities or even among Sovietologists

recognized the deepening internal crisis of confidence that

would lead to the implosion of the Soviet Empire. The

opposing sides had each deployed tens of thousands of

nuclear weapons, as well as vast armies, air forces, and

navies across the globe. Soviet forces were occupying

Afghanistan and appeared on the brink of crushing an uprising

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of ill-equipped, ill-trained guerrillas. In El Salvador, a Soviet-

backed insurgency was on the brink of victory.

Beyond the confrontation between the United States and

Soviet Union lay a world that differed enormously from today.

China was only emerging from the dark years of Mao‘s rule.

To China‘s south, India remained mired in an almost medieval

level of poverty, from which it appeared unlikely to escape. To

the sub-continent‘s west, the Middle East was as plagued by

political and religious troubles as today. But no one could have

predicted then that within 25 years the United States would

wage two major wars against Saddam Hussein‘s regime and

commit much of its ground power to suppressing simultaneous

insurgencies in Iraq and Afghanistan.

The differences between the culture and organization of the

American military then and now further underline the extent of

the disruptions with the past. The lack of coordination among

the forces involved in overthrowing the ―New Jewel‖

movement in Grenada in October 1983 reminds us that at the

time jointness was a concept honored more in the breach than

observance. That situation led to the Goldwater-Nichols Act in

1986.

In terms of capabilities, stealth did not yet exist outside of

the research and development communities. The M-1 Tank

and the Bradley Fighting Vehicle were only starting to reach

the Army‘s forward deployed units.

1.5.2 Trends Influencing the World’s Security

Trend analysis is the most fragile element of forecasting.

The world‘s future over the coming quarter of a century will be

subject to enormous disruptions and surprises, natural as well

as man-made. These disruptions, and many other contiguous

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forces, can easily change the trajectory of any single trend.

The Joint Operating Environment recognizes that many, if not

all, of the trends and trajectories of the future will be non-

linear. But for the purpose of analysis, it has used a traditional

approach to examine many of the trends and utilized

conservative estimates. For instance, demographically, it has

used estimates from sources such as the U.S. Census

Bureau. Economically, the Joint Operating Environment

assumes growth rates for developed countries of 2.5% and

4.5% for developing countries, including China. It is in this

manner that this study considers the trends below. In the final

analysis, the value of the trends lies not in accurately

predicting them, but in intuiting how they might combine in

different ways to form more enduring contexts for future

operations. Trend analysis can also help in identifying some

indicators or signposts that one can use to ―check‖ the path

that the world takes into the future and make adjustments as

necessary. Nevertheless, the resource and strategic

implications of even a conservative and linear rate of increase

possess consequences that suggest a dark picture of the

future.

Demograpihics

A good place to begin the discussion of trends is

demographics, because what is happening demographically

today, unless altered by some catastrophe, has predictable

consequences for the populations of regions and states.

Equally important, it possesses implications for future strategic

postures and attitudes. In total, the world will add

approximately 60 million people each year and reach a total of

8 billion by the 2030s. Ninety-five percent of that increase will

occur in developing countries. The more important point is that

the world‘s troubles will occur not only in the areas of abject

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poverty, but also to an even greater extent in developing

countries, where the combination of demographics and

economy permits populations to grow, but makes meeting

rising expectations difficult. Here, the performance of the

global economy will be key in either dampening down or

inflaming ethnically or religiously-based violent movements.

The developed world confronts the opposite problem.

During the next 25 years population growth in the developed

world will likely slow or in some cases decline. In particular,

Russia‘s population is currently declining by 0.5% annually,

and given Russian health and welfare profiles, there is every

prospect that decline will continue, barring a drastic shift in

social attitudes or public policy. As a recent Center for

Strategic International Studies (CSIS) report suggested,

―Russia needs to cope with a rate of population decline that

literally has no historical precedent in the absence of

pandemic.‖131 To Russia‘s west, a similar, albeit less

disastrous situation exists. Over all, European nations stopped

replacing their losses to deaths in 2007, and despite

considerable efforts to reverse those trends, there is little

likelihood their populations will significantly increase by the

2030s. This raises serious concerns about the sustainability of

economic growth in that region. It also has serious

implications for the willingness of European societies to bear

the costs involved in lives and treasure that the use of military

force inevitably carries with it.

Likewise, Japan‘s population will fall from 128 million to

approximately 117 million in the 2030s, but unlike the case of

Russia this will result not from any inadequacy of Japanese

medical services, which are among the world‘s best, but from

the collapse of Japan‘s birth rate. The Japanese are taking

serious steps to address their demographic decline, a fact

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which explains their major research and development efforts

in the field of robotics as well as their shift to a capital-

intensive economy.

Globalitation

For the most part, the developed world recognizes that it has a

major stake in the continuing progress of globalization. The

same can be said for those moving into the developed world.

Nevertheless, one should not ignore the histories and

passions of popular opinion in these states as they make their

appearance. One should not confuse developed world

trappings for an underlying stability and maturity of civil

societies. A more peaceful cooperative world is only possible if

the pace of globalization continues. In particular, this means

engaging China and other nations politically and culturally as

they enter into the developed world.

The critics of globalization often portray its dark side in the

inequality of rich and poor. In some worst -case scenarios,

they portray the rise of resentment and violence throughout

the world as a direct result of globalization. Not surprisingly,

the future is likely to contain both good and bad as

globalization accelerates the pace of human interaction and

extends its reach

Energy

To meet even the conservative growth rates posited

above, global energy production would need to rise by 1.3%

per year. By the 2030s, demand would be nearly 50% greater

than today. To meet that demand, even assuming more

effective conservation measures, the world would need to add

roughly the equivalent of Saudi Arabia‘s current energy

production every seven years.

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Unless there is a major change in the relative reliance on

alternative energy sources, which would require vast

insertions of capital, dramatic changes in technology, and

altered political attitudes toward nuclear energy, oil and coal

will continue to drive the energy train. By the 2030s, oil

requirements could go from 86 to 118 million barrels a day

(MBD). Although the use of coal may decline in the

Organization for Economic Cooperation and Development

(OECD) countries, it will more than double in developing

nations. Fossil fuels will still make up 80% of the energy mix in

the 2030s, with oil and gas comprising upwards of 60%. The

central problem for the coming decade will not be a lack of

petroleum reserves, but rather a shortage of drilling platforms,

engineers and refining capacity. Even were a concerted effort

begun today to repair that shortage, it would be ten years

before production could catch up with expected demand. The

key determinant here would be the degree of commitment the

United States and others would display in addressing the

dangerous vulnerabilities the growing energy crisis presents

1.5.3 The Implications for the Joint Force War in the the Twenty-

First Century

As the discussion of trends and contexts above has

suggested, the roles and missions of the Joint Force will

include the protection of the homeland, the maintenance of the

global commons, the deterrence of potential enemies, and,

when necessary, fighting and winning conflicts that may occur

around the world. Such challenges are by themselves

daunting enough, but they will occur in a period characterized

by radical technological, strategic, and economic change, all

of which will add to the complexities of the international

environment and the use of military force. America‘s position

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in the world, unprecedented in almost every respect, will

continue to present immense challenges to its military forces.

Rapidly changing trends within the contexts described in the

previous section will have profound implications for the

character of war itself and the methods by which the Joint

Force will wage it. Yet, the nature of war will remain closer to

Agincourt than to Star Trek. At its heart, war will always

involve a battle between two creative human forces. Our

enemies are always learning and adapting. They will not

approach conflicts with conceptions or understanding similar

to ours. And they will surprise us. No amount of technology,

conceptualization, or globalization will change those realities.

Moreover, the employment of military force will continue to be

conditioned by politics -- not only those of the United States

and its allies, but by those of its opponents. Above all, joint

force commanders, their staffs, and their subordinates must

have a clear understanding of the strategic and political goals

for which they conduct military operations. In almost every

case, they will find themselves working closely with partners, a

factor which will demand not only a thorough understanding of

U.S. political goals, but coalition goals as well.

It is in this political-strategic environment that the greatest

surprises for Americans may come. The United States has

dominated the world economically since 1915and militarily

since 1943. Its dominance in both respects now faces

challenges brought about by the rise of powerful states.

Moreover, the rise of these great powers creates a strategic

landscape and international system, which, despite continuing

economic integration, will possess considerable instabilities.

Lacking either a dominant power or an informal organizing

framework, such a system will tend toward conflict. Where and

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how those instabilities will manifest themselves remains

obscure and uncertain.

Between now and the 2030s, the military forces of the United

States will almost certainly find themselves involved in

combat. Such involvement could come in the form of a major

regular conflict or in a series of wars against insurgencies.

And as this document has suggested, they will certainly find

themselves engaged not only against terrorist organizations,

but against those who sponsor them. One of the great

problems that confronts American strategists and military

planners is the conundrum of preparing for wars that remain

uncertain as to their form, location, level of commitment, the

contribution of potential allies, and the nature of the enemy.

The only matter that is certain is that joint forces will find

themselves committed to conflict against the enemies of the

United States and its Allies, and in defense of its vital

interests.

1.5.4 Preparing for War

There are two ominous scenarios that confront joint forces

between now and the 2030s. The first and most devastating

would be a major war with a powerful state or hostile alliance

of states. Given the proliferation of nuclear weapons, there is

the considerable potential for such a conflict to involve the use

of such weapons. While major regular war is currently in a

state of hibernation, one should not forget that in 1929 the

British government adopted as its basic principle of defense

planning the assumption that no major war would occur for the

next ten years. Until the mid-1930s ―the ten year rule‖ crippled

British defense expenditures. The possibility of war remained

inconceivable to British statesmen until March 1939.

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The one approach that would deter a major conflict involving

U.S. military forces, including a conflict involving nuclear

weapons, is the maintenance of capabilities that would allow

the United States to wage and win any possible conflict. As

the Romans so aptly commented, ―if you wish for peace,

prepare for war.‖ Preventing war will in most instances prove

more important than waging it. In the long-term, the primary

purpose of the military forces of the United States must be

deterrence, for war in any form and in any context is an

immensely expensive undertaking both in lives and national

treasure. When, however, deterrence fails, then, the military

effectiveness of those forces will prove crucial. Here the

efforts that have gone into preparing U.S. forces for conflict at

their various training centers must continue to receive the

same support and attention in the future that they have over

the course of the past 30 years. As the Japanese

warrior/commentator Miyamoto Musashi noted in the

seventeenth century:

There is a rhythm in everything, but the rhythms of

the art of war are especially difficult to master

without practice…. In battle, the

way to win is to know the opponent’s rhythms while

using unexpected rhythms yourself, producing

formless rhythms from the rhythms of wisdom.261

The second ominous scenario that confronts the Joint Force

is the failure to recognize and fully confront the irregular fight

that we are in. The requirement to prepare to meet a wide

range of threats is going to prove particularly difficult for

American forces in the period between now and the 2030s.

The difficulties involved in training to meet regular and

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nuclear threats must not push preparations to fight irregular

war into the background, as occurred in the decades after

the Vietnam War. Above all, Americans must not allow

themselves to be deluded into believing their future

opponents will prove as inept and incompetent as Saddam

Hussein‘s regime was in 1991 and again in 2003. Having

seen the capabilities of U.S. forces in both regular and

irregular war, future opponents will understand ―the American

way of war‖ in a particularly detailed and thorough way.

In Iraq and Afghanistan our opponents have displayed

considerable capacity to learn and adapt in both the political

and tactical arenas. More sophisticated opponents of U.S.

military forces will certainly attack American vulnerabilities.

For instance, it is entirely possible that attacks on computers,

space, and communications systems will severely degrade

command and control of U.S. forces. Thus, those forces

must possess the ability to operate effectively in degraded

conditions.

In planning for future conflicts, joint force commanders and

their planners must factor two important constraints into their

calculations: logistics and access. The majority of America‘s

military forces will find themselves largely based in North

America. Thus, the first set of problems involved in the

commitment of U.S. forces will be logistical. In the 1980s

many defense pundits criticized the American military for its

supposed over-emphasis on logistics, and praised the

German Wehrmacht for its minimal ―tooth to tail‖ ratio in the

Second World War. What they missed was that the United

States had to project its military forces across two great

oceans, then fight massive battles of attrition in Europe and

in East Asia. Ultimately, the logistical prowess of U.S. and

Allied forces, translated into effective combat forces,

defeated the Wehrmacht on the Western Front, crushed the

15

Luftwaffe in the skies over Germany, and broke Imperial

Japan‘s power.

The tyranny of distance will always influence the conduct of

America‘s wars, and joint forces will confront the problems

associated with moving forces over great distances and then

supplying them with fuel, munitions, repair parts, and

sustenance. In this regard, a measure of excess is always

necessary, compared to ―just in time‖ delivery. Failure to

keep joint forces who are engaged in combat supplied could

lead to disaster, not just unstocked shelves. Understanding

that requirement represents only the first step in planning,

but it may well prove the most important.

The crucial enabler for America‘s ability to project its military

power for the past six decades has been its almost complete

control over the global commons. From the American

standpoint, the Battle of the Atlantic that saw the defeat of

the German U-boat menace in May 1943 was the most

important victory of the Second World War. Any projection of

military power in the future will require a similar enabling

effort, and must recognize that the global commons have

now expanded to include the domains of cyber and space.

The Joint Force must have redundancy built in to each of

these areas to ensure that access and logistics support are

more than ―single-point safe‖ and cannot be disrupted

through a single enemy point of attack.

In America‘s two recent wars against Iraq, the enemy made

no effort to deny U.S. forces entry into the theater. Future

opponents, however, may not prove so accommodating.

Hence, the second constraint confronting planners is that the

United States may not have uncontested access to bases in

the immediate area

16

from which it can project military power. Even in the best

case, allies will be essential to providing the base structure

required for arriving U.S. forces. But there may be other

cases where uncontested access to bases is not available for

the projection of military forces. This may be because the

neighborhood is hostile, or because smaller friendly states

have been intimidated. Hence, the ability to seize bases by

force from the sea and air could prove the critical opening

move of a campaign.

Given the proliferation of sophisticated weapons in the

world‘s arms markets - potential enemies - even relatively

small powers will be able to possess and deploy an array of

longer-range and more precise weapons. Such capabilities in

the hands of America‘s enemies will obviously threaten the

projection of forces into a theater as well as attack the

logistical flow on which U.S. forces will depend. Thus, the

projection of military power could become hostage to the

ability to counter long-range systems even as U.S. forces

begin to move into a theater of operations and against an

opponent. The battle for access may prove not only the most

important, but the most difficult.

One of the major factors in America‘s success in deterring

potential aggressors and projecting its military power over

the past half century has been the presence of its naval

forces off the coasts of far-off lands. Moreover, those forces

have also proven of enormous value in relief missions when

natural disasters have struck. They will continue to be a

significant factor in the future. Yet, there is also the rising

danger with the increase in precision and longer range

missiles that presence forces could be the first target of an

enemy‘s action in their exposed positions.

17

1.5.5 The Conduct of Military Operations in the Twenty-First

Century

The forms of future war will each present peculiar and

intractable challenges to joint forces. The U.S. will always

seek to fight and operate with partners, leading where

appropriate, and prepared to act alone when required to

support our vital national interests. However, there is every

likelihood that there will be few lines of delineation between

one form of conflict and another. Even in a regular war,

potential opponents, engaged in a life and death struggle with

the United States, may engage U.S. forces across the

spectrum of conflict. Thus, the Joint Force must expect attacks

on its sustainment, its intelligence, surveillance and

reconnaissance (ISR) capabilities, and its command and

control networks. The Joint Force can expect future opponents

to launch both terrorist and unconventional attacks on the

territory of the continental United States, while U.S. forces

moving through the global commons could find themselves

under persistent and effective attack. In this respect, the

immediate past is not necessarily a guide to the future.

Deterrence of aggression and of certain forms of warfare

will remain an important element of U.S. national security

strategy, and the fundamentals of deterrence theory will apply

in the future as they have for thousands of years of human

history. Deterrence operations will be profoundly affected by

three aspects of the future joint operating environment.

First, U.S. deterrence strategy and operations will need to

be tailored to address multiple potential adversaries. A ―one-

size-fits-all‖ deterrence strategy will not suffice in the future

joint operating environment. Deterrence campaigns that are

tailored to specific threats ensure that the unique decision

calculus of individual adversaries is influenced.

18

Second, the increased role of transnational non-state

actors in the future joint operating environment will mean that

U.S. deterrence operations will have to find innovative new

approaches to ―waging‖ deterrence against such adversaries.

Non-state actors differ from state actors in several key ways

from a deterrence perspective. It is often more difficult to

determine precisely who makes the key decisions one seeks

to influence through deterrence operations. Non -state actors

also tend to have different value structures and vulnerabilities.

They often possess few critical physical assets to hold at risk,

and are sometimes motivated by ideologies or theologies that

make deterrence more difficult (though usually not

impossible). Non-state actors are often dependent on the

active and tacit support of state actors to support their

operations. Finally, our future deterrence operations against

non-state actors will likely suffer from a lack of well

established means of communications that usually mark state-

to-state relations.

Third, continued proliferation of weapons of mass

destruction will make the U.S. increasingly the subject of the

deterrence operations of others. As such, the U.S. may find

itself in situations where its freedom of action is constrained

unless it can checkmate the enemy‘s deterrent logic.

U.S. nuclear forces will continue to play a critical role in

deterring, and possibly countering, threats to our vital interests

in the future joint operating environment. Additionally, U.S.

security interests will be advanced to the degree that its

nuclear forces are seen as supporting global order and

security. To this end, the U.S. must remain committed to its

moral obligations and the rule of law among nations. It must

provide an example of a responsible and ethical nuclear

power in a world where nuclear technology is available to a

wide array of actors. Only then will the existence of powerful

19

U.S. nuclear forces, in support of the global order, provide

friends and allies with the confidence that they need not

pursue their own nuclear capabilities in the face of growing

proliferation challenges around the world.

Unfortunately, we must also think the unthinkable –

attacks on U.S. vital interests by implacable adversaries who

refuse to be deterred could involve the use of nuclear

weapons or other WMD. For both deterrence and defense

purposes our future forces must be sufficiently diverse and

operationally flexible to provide a wide range of options to

respond. Our joint forces must also have the recognized

capability to survive and fight in a WMD, including nuclear,

environment. This capability is essential to both deterrence

and effective combat operations in the future joint operating

environment.

If there is reason for the joint force commander to

consider the potential use of nuclear weapons by adversaries

against U.S. forces, there is also the possibility that sometime

in the future two other warring states might use nuclear

weapons against each other. In the recent past, India and

Pakistan have come close to armed conflict beyond the

perennial skirmishing that occurs along their Kashmir frontier.

Given India‘s immense conventional superiority, there is

considerable reason to believe such a conflict could lead to

nuclear exchanges. As would be true of any use of nuclear

weapons, the result would be massive carnage, uncontrolled

refugee flows, and social collapse all in all, a horrific human

catastrophe. Given 24/7 news coverage, the introduction of

U.S. and other international forces to mitigate the suffering

would seem to be almost inevitable.

Nuclear and major regular war may represent the most

important conflicts the Joint Force could confront, but they

remain the least likely. Irregular wars are more likely, and

20

winning such conflicts will prove just as important to the

protection of America‘s vital interests and the maintenance of

global stability.

A significant component of the future operating

environment will be the presence of major actors which are

not states. A number of transnational networked organizations

have already emerged as threats to order across the globe.

These parasitic networks exist because communications

networks around the world enable such groups to recruit, train,

organize, and connect. A common desire to transcend the

local regional, and international order or challenge the

traditional power of states characterizes their culture and

politics. As such, established laws and conventions provide no

barrier to their actions and activities. These organizations are

also becoming increasingly sophisticated, well-connected, and

well-armed. As they better integrate global media

sophistication, lethal weaponry, potentially greater cultural

awareness and intelligence, they will pose a considerably

greater threat than at present. Moreover, unburdened by

bureaucratic processes, transnational groups are already

showing themselves to be highly adaptive and agile.

Irregular adversaries will use the developed world‘s

conventions and moral inhibitions against them. On one hand

the Joint Force is obligated to respect and adhere to

internationally accepted ―laws of war‖ and legally binding

treaties to which the United States is a signatory. On the other

hand, America‘s enemies, particularly the non-state actors, will

not find themselves so constrained. In fact, they will likely use

law and conventions against the U.S. and its partners.

21

PERTEMUAN 2

Naval Ship Design

2.1 Pendahuluan


a. History of Structural Design-Comercial VS Naval

b. Recent Trends In Naval Vessel Design

c. Naval Structural Design Philosopy

d. Structural Design for Environmental and Operational Loads

e. Structural Design for Military Loads

2.2 Tujuan Instruksional Umum


memahami History of Structural Design-Comercial VS Naval, Recent

Trends In Naval Vessel Design, Naval Structural Design Philosopy,

Structural Design for Environmental and Operational Loads, Structural

Design for Military Loads

2.3 Tujuan Instruksional Khusus


menjelaskan History of Structural Design-Comercial VS Naval, Recent

Trends In Naval Vessel Design, Naval Structural Design Philosopy,

Structural Design for Environmental and Operational Loads, Structural

Design for Military Loads

2.4 Skenario Pembelajaran


penilaian





22

2.5 Ringkasan Materi:

2.5.1 History of Structural Design-Comercial VS Naval

The structural design of warships has diverged from and

converged with commercial ships throughout history. The Greek

and Roman ramming ships (triremes and biremes) were built

light but with a heavily reinforced keel, compared with the

heavier but more uniform amphora ships of the era. In the

Middle Ages few nations had standing navies and most warfare

was conducted from merchant ships adapted to carry light

guns. In the 1500s the advent of heavy guns and gunports led

to the creation of fleets of specialized ships-of-the-line, having

reinforced decks and hulls to absorb the weight and recoil of the

guns and resist the impact of shot. Even so, warships were

often constructed in the same shipyards as commercial ships;

both designers and workers had little or no difficulty in switching

between the two and in fact often shared technological

advances between the naval and commercial ships. For

example, during the late 1700s many of the European East

Indies fleets built their armed commercial ships using naval

practices; and in the early 1800s, hull strength improvements

pioneered by the British East Indies Company were improved

upon and incorporated into British warships (later, by other

navies as well).

The growing use of iron in shipbuilding from 1820-1860 caused

both navies and commercial ship-owners to rethink design and

build practices. Once again, there was considerable sharing of

new ideas and technologies between the two sectors. Most of

this advance occurred in Britain, the centre of the Industrial

Revolution, where civil engineers working on railways and

bridges were bringing their hard-won knowledge of structural

design practices into the shipbuilding arena; in particular, the

box-girder system developed for the Britannia Bridge became

the paradigm for longitudinal iron framing in ships. In fact, with

23

most navies at this time (soon after the Napoleonic Wars)

operating under austere budgets, much of the fundamental

research into metallurgy and the design of joints was carried out

for the commercial sector, which was undergoing a rapid

expansion due to the increasingly-reliable marine steam engine.

At this time, commercial classification societies.

Beginning in the 1870s, the British navy led the way in

developing structural design practices using calculations based

on fundamental engineering principles. For example, warship

designers began calculating bending moments based on the

static balance of a ship on a wave and a careful enumeration of

the weight distribution along its length. By contrast, most

classification societies at the time settled on semi-empirical

formula that related bending moments to the length and

displacement of the ship. This rule was quite adequate for the

large number of relatively similar merchant ships that were

constructed under classification Rules. Navies, however,

developed and built relatively small numbers of ships, and the

requirements for each one tended to evolve faster than for

merchant ships; so naval constructors tended to revert to basic

engineering principles and lessons learned in their designs.

More importantly, the ability of naval constructors to develop

scantlings was directly related to the rapid progress of naval

architecture education that was specifically directed to serving

navy needs. Put simply, by the early 1900s many navies around

the world had funded schools of naval architecture, whose

graduates overwhelmingly went back to work for the ―sponsor‖.

Most naval design bureaus possessed both the ability and

managerial support to carry out complex calculations. By

contrast, the number of graduate engineers in commercial

shipyard design offices (versus designers coming up from the

shop floor) was still limited.

24

This situation slowly changed during and after World War II for

two related reasons. First, the number of graduate engineers

increased dramatically as companies and governments

recognized the need for higher levels of knowledge and skill in

the new economy, insisting on university degrees for their

engineering workforce. Second, investment in science and

technology also grew sharply, much of it directed to universities

and research centres to advance the state of the art and to

solve practical problems. An early example of this was the

formulation in 1946 of the Ship Structure Committee (SSC) as

an outgrowth of a US Navy Board of Investigation to determine

the causes of the brittle fracture of welded merchant ships

during the war. Similar investigations were conducted by the

Admiralty Ship Welding Committee (later the Advisory

Committee on Structural Steel) in the UK. It is interesting to

note that both of these government committees included their

respective national classification societies as integral members

– recognizing that technology transfer between commercial and

naval practices could be of benefit. The research sponsored by

these organizations included several full-scale tests that greatly

advanced the development of fundamental engineering

requirements for structural rules and ship specifications, while

the new breed of university-trained engineers now possessed

the requisite knowledge to apply advanced technologies. Over

time, the development of improved methods of calculation such

as probabilistic analysis, and the use of computer-aided design

tools such as finite-element codes, were promoted by

classification societies using state-of-the-art engineering

techniques. The ability to perform detailed structural analyses

with high degrees of confidence has aided the rapid growth in

specialized vessels such as LNG carriers, FPSOs and ultra-

large container ships.

25

Although the computational design and analysis processes and

supporting tools applied to naval and commercial vessels were

converging, there were still elements of significance which

made them unique from one another. Navies continued to

develop and refine their own design standards based on

―lessons learned‖ fro m battle damage experience and

extensive research into structural response. From the mid-

1940s to the 1960s, many navies carried out numerous full-

scale trials using decommissioned or captured warships to

examine everything from hull girder bending to the response of

foundations under shock loading. From the 1980s to the 1990s,

full-scale trials were largely replaced by scale model tests and

increasingly sophisticated computer-aided analysis programs,

in many cases based on the same principles as commercial

software codes. The results of these tests and trials have led to

the development of specialized steels for naval ships, and

comprehensive standards and specifications for construction

details to improve damage resistance. For example, most

navies specified the use of symmetrical ―T‖ stiffeners and

continuous welding of members to inhibit structural failure after

shock loading.

Differences such as operations and maintenance also

contributed to the divergence of naval and commercial ship

design standards and methods. Most cargo-carrying ships had

a great variation in loading conditions (fully laden or in ballast),

resulting in greater fatigue cycles than found on naval vessels,

resulting in heavier scantlings for comparable sizes. For

another example, navy crews continuously inspected and

painted hull structures, whereas for commercial ships these

activities were carried out only periodically, e.g., during

drydockings; so in most class Rules, a corrosion (wastage)

26

allowance was specifically called out, which was generally not

present in naval ship design criteria.

Perhaps the most important reason for the continued difference

in naval and commercial design methods was the relative

―democracy‖ of the classification society Rules process,

compared with the ―single party rule‖ generally pre sent in naval

design bureaus. Simply put, classification societies had to (and

still must) adjudicate changes to Rules among numerous

stakeholders, including owners, operators, shipyards and

government regulators. This does not mean so much a ―drive

for the minimum acceptable‖ as much as a balance of many,

often strongly-held, views on the relative importance of cost,

risk, efficiency and safety. By contrast, naval design bureaus

have been fairly small, and though they too must be

accountable to numerous stakeholders as well, in actual fact

the changes to structural design methods and standards were

made and approved by a small cadre of highly experienced

technical staff.

This is now changing. In the post-Cold War era starting in the

1990s and evolving to the present day, many navies have

experienced sweeping cuts in their technical staffs, as

governments changed the way they acquired warships. In the

past these navies had designed their own warships, to their

own specifications. Now, the ship design and construction

process is handled by commercial organizations with the navies

providing only performance criteria to be met and technical

guidance as necessary. In short, many navies can no longer

develop and maintain their own standards and specifications.

Starting with the British navy, but rapidly expanding to others,

the responsibility for these standards have been transferred to

commercial classification societies, under close naval oversight.

27

Although this process is still evolving, early experience has

indicated that many commercial-like ship design processes with

modified naval structural standards are, in fact, quite

comparable to traditional military standards, and in some cases

such as high-speed vessels, certain military-like standards are

needed for the ever-more stringent requirements of commercial

fast ferries. It is likely that naval and commercial vessel Rules

will continue to evolve in parallel and may show some overlaps,

given the current concern by commercial ship owners to

consider survivability against terrorist-like threats. The fact that

classification societies commonly use the same fundamental-

engineering principles as do navies means that naval and

commercial structural design can be developed side-by-side

using comparable means of analysis, so that differences

between them can be properly attributed to required use, and

not to any misunderstanding of methodology.

2.5.2 Recent Trends in Naval Vessel Design

Some of the current trends that will affect the way naval vessels

are designed and built are:

• Modularity, flexibility and multiple missions: The rapid

development of open software standards, ―plug-and-play‖

systems and lea ps in autonomous, remotely-operated

vehicles means that future naval vessels may be configured

to carry out a variety of missions that span the traditional

roles of force projection, combatant and support, either

simultaneously or in sequence; thus, conventional ―rules‖ will

have to be re-examined (for example, will flexible-mission

ships need to be shock-hardened for mine warfare, if the

actual operations are carried out by remote unmanned

vehicles?).

• Enhanced Stealth: In the post-Cold War era, warships will

likely operate far more in littoral regions rather than in open

28

ocean. Signature management (stealth) is increasingly seen

as important to reducing vulnerability to detection and attack

in such environments. Novel structural arrangements,

features and materials are being developed to reduce radar

cross-section, acoustic and thermal emissions, and even

visual signatures.

• Changing Threats: Since the end of the Cold War the nature

of the threats faced by naval vessels has radically changed.

Although prudent designers will always consider ―blue water‖

threats such as submarine lau nched torpedoes and nuclear

attack, it is far more likely that the ships of the near future will

face low tech weapons such as simple mines, easily

available missiles and high-speed boat attacks. Operations in

the littoral will make platforms more vulnerable to low tech

attack and allowances must be made for survivability in these

areas.

• High speed: The age of 40-knot warships was thought to

have ended in World War II, but the emphasis on littoral

operations have revived interest in the tactical advantages of

high speed. Extensive research is needed in the areas of hull

slamming response, fatigue strength and vibrations in thin

structures, in order to develop means to reduce maintenance

and increase hull life.

• Multihull/ advanced hulls: Although novel hull types such as

catamarans, SWATHs, trimarans, hydrofoils, surface-effect

ships, etc. have been in existence for a long time,

requirements for increased speed as described above,

improved

29

• Materials: Shipyards and owners (including navies) continue

to search for newer materials and material systems that will

improve performance and / or reduce construction and

through-life costs. Composite materials and systems (e.g.,

metal-and-plastic sandwiches), novel metals such as

titanium, and coating systems all are being considered to

provide such attributes as lighter weight, ease of fabrication

and higher resistance to corrosion. Another factor is the

increased awareness of terrorist threats that may drive both

naval and commercial vessel owners to consider additional

hardening measures.

• Naval construction by non-indigenous shipyards: During

most of the 20th century, developed nations built their own

naval ships in their own shipyards. In recent years, some of

those nations have begun to contract with foreign (i.e., non-

indigenous) yards to build their naval vessels, and the trend

appears to be on the rise. In some cases, this is due to lower

costs at the foreign yards; in other cases, the sophisticated

integration capabilities required simply do not exist locally.

The implication for structural engineering is a move away

from naval standards to commercial standards, which are

well understood by the foreign yards.

2.5.3 Naval Structural Design Philosophy

Naval ships have traditionally been designed to in-house

standards. A vision was developed for a system of naval ship

regulation based on classification and combining the

strengths of the naval and the commercial regulatory regimes

to provide through life care of naval ships. This chapter gives

a brief survey of known traditional approaches used by

different navies and a brief survey of various approaches by

different classification societies that have published rules for

naval ships.

30

Recognizing that there is no body equivalent to IMO

for naval ships, a NATO Specialist Team on ―Naval Ship

Safety and Classification‖ has been established to develop a

―Naval Ship Code‖. The Code aims to fill the void by

providing the framework for navies to gain assurance that

acceptable levels of safety are achieved. In doing so, the

Code will replicate the link between IMO and Classification

Societies and promote improved ship design and a greater

consistency and transparency of safety standards

Structural Design for Environmental and Operational

Loads

Design Enviromental Loads

As defined by Lloyd‘s Register‘s Rules and Regulati ons

for the Classification of Naval Ships, environmental

conditions include natural phenomena such as wind,

wave and currents and also ice and thermal conditions.

Wave Induced Loads

Global design loads can be divided as follows:

• Hull girder loads are common to both commercial and

military vessels. These include still water shear forces

and associated bending moments, low frequency

vertical wave shear forces and associated bending

moments deriving from hydrodynamic pressures, high

frequency shear forces and associated bending

moments, consequence of slamming phenomena;

• Extreme hull girder loads are those used to assess

ultimate strength and must be derived after an overall

examination of the matrix of all loads which can be

expected;

• Hull girder loads for residual strength assessment are

usually defined to be a specific set of conditions for a

specified period of time. Additional considerations for

31

residual strength assessment are covered in more

depth in Chapter 6.

Still water maximum global loads are to be evaluated

taking account of the worst loading conditions, which are

defined by the Rules and/or the Owners and may vary as

a function of the ship type. It should be noted that the still

water bending moment for a naval ship is, as a rule, less

than that of a commercial vessel.

Like for merchant ships, wave induced loads are defined

by means of physical principles rather than empirical

formulations. As suggested by Boccalatte et al. (2003),

the influence of the main parameters, which govern the

ship response at sea, is to be taken into account.

Starting from IACS procedure, in line with STANAG

4154, this leads to the definition of coefficients, which

consider the peculiar slim hull shapes of combatant

ships, their generally non-vertical sides and their speed.

The formulations proposed by the Classification

Societies, starting from the merchant ship rules, hence

include correction factors that may be also derived by

direct calculation methods up to non-linear ship motion

analyses.

Like high speed craft or some merchant vessel types (i.e.

container or cruise ships), bow flare impacts can give

rise to additional bending moments, which can

significantly increase the design sagging. The evaluation

of such pressures can be carried out as mentioned.

The calculation of ship motions is fundamental for a

correct definition of the dynamic loads acting on the

vessel. Not only such an evaluation allows obtaining the

dynamic portion of local pressures, but also the

32

components of acceleration in the three directions, both

those acting in way of ship centre of gravity and their

distribution along the vessel. A reliable definition of these

accelerations is essential in order to correctly evaluate

the structural behaviour of important components, like for

instance combat systems equipment foundations, and

the dynamic factors that increase loads like those

deriving from parking of aircraft.

Slam induced whipping loads

Whipping is a transient hull response resulting from bow

flare or bottom slamming, which generally induces low

frequency (mainly first mode natural hull frequency) hull

girder bending moments. The effect of whipping loads on

fatigue damage may be significant for more slender and

higher speed vessels (Hansen et al., 1995). Longitudinal

stresses may be significantly affected by slamming

impacts, especially in small and medium size ships.

Generally high wave-induced stresses and high whipping

stresses appear to occur at the same time, but there

tends to be a phase between the whipping initiation and

the peak of hogging ranging from -20 to 70 degrees

(Jiao, 1996). The occurrence of slamming is predicted in

the analytical approach based on the relative velocity

against waves (Hansen et al., 1995).

2.5.4 External Blast Events

As previously stated these result from proximity/stand-off

blasts from, Far field nuclear warheads; stand-off,

proximity or contact bursts from conventional high

explosive (HE) warheads; enhanced blast warheads e.g.

fuel air explosions (FAE), asymmetric/terrorist activity

and discharge of one's own weapons: muzzle blast and

missile motor efflux.

33

Design Requirements

In principle all air blast effects follow the same scaling

law (R/We1/3) independent of the kind of explosion,

nuclear (Glasstone 1957) or non-nuclear (Baker 1983).

The significant differences originate from the

relationships between the characteristic length of the

blast wave and the characteristic lengths of the loaded

structure. The absolute length of a nuclear blast wave is

about 100 times bigger than that of a conventional one.

Thus the characteristic length of a nuclear pulse is in the

order of the ship's length and therefore the loading

mainly causes global effects, while the characteristic

length of conventional explosions is in the order of frame

spacing or deck height respectively, therefore the loading

mainly causes local effects only. The blast-influenced

area is comparable to that characteristic wavelength.

The time of action of the blast wave is also related to the

wavelength. Therefore the response of the structure is

strongly influenced by the response times (natural

frequencies) of the system. Consideration of these

relationships establishes whether impulse effects or

quasi-static behaviour will prevail in the response, thus

determining the most adequate methods of analysis to

be adopted during design.

All components of the ship's structure which affect the

operational and survival capability of the ship should be

designed to meet a set of pre-determined criteria. These

criteria are normally determined by the role of the vessel

34

and set out in the operational requirements. This may be

accomplished by calculation (Biggs 1964) as discussed

in the previous paragraph and/or by use of pertinent data

from large-scale blast experiments

In view of the time dependence of the impulsive loadings

involved in Air Blast, the use of static analysis to

compute the structural response to air blast loadings has

severe limitations, however if coupled with a suitable

dynamic loading factor they can be used to provide a first

approximation for design purposes Forrestal et al. 1977).

35

PERTEMUAN 3

Military and Commercial Shipbuilding

3.1 Pendahuluan


a. Military and Commercial Shipbuilding Trends

b. How Military and Commercial Shipbuilding Differ

c. The Potential for Ferign Military Sales

d. Integration Versus Specialisation at the Shipyard Level



memahami Military and Commercial Shipbuilding Trends, How Military

and Commercial Shipbuilding Differ, The Potential for Ferign Military

Sales, Integration Versus Specialisation at the Shipyard Level



menjelaskan Military and Commercial Shipbuilding Trends, How

Military and Commercial Shipbuilding Differ, The Potential for Ferign

Military Sales, Integration Versus Specialisation at the Shipyard Level



b. penilaian

c. Dosen menjelaskan materi kuliah

d. Diskusi dan tanya jawab dengan mahasiswa

e. Pembagian kelompok

f. Evaluasi pencapaian belajar


3.5.1 Shipbuilding Trends

The demand for commercial shipbuilding in the global

marketplace has increased from a lull in the late 1980s to a

peak in 2002 and 2003. Some national shipbuilding industries,

notably the German and the Dutch, recovered during this

36

period. The French shipbuild-ing industry took somewhat longer

but eventually recovered. The US commercial shipbuilding

industry, largely a protected one and un-competitive in the

global market, also recovered slowly from a similar downturn in

its domestic demand. The United Kingdom‘s commer-cial

industry began to recover in the early 1990s before fading again

in the middle part of the decade. As of early 2003, there was

only one sizable commercial ship under construction in a UK

shipyard (the HMS Anvil Point, a roll-on/roll-off cargo ship).

The United Kingdom has, however, sustained a military ship-

building industrial base of substantial size throughout the last

quarter-century. The value of its future domestic demand is

expected to be on the order of that of France and Japan and

much larger than Germany‘s. However, UK shipbuilders are

expected to export very few military ships compared with

projects of the Germans and French.

3.5.2 Differences Between Military and Commercial Shipbuilding

If the UK commercial market is to expand, military shipbuilders

will presumably have to begin building commercial ships,

because the commercial industrial base is so small. The

construction of all but the most complex commercial ships,

however, differs dramatically from that of warships along

several dimensions:

• Ship size and complexity. The average commercial ship is

about three times as big as the average military ship and thus

cannot be built in facilities sized for military ships. At the same

time, the average commercial ship is much simpler (e.g., no

weapon sys-tem) than the average military ship.

• Acquisition process. Commercial ship owners are

accustomed to much simpler contracting, designing,

construction, and testing processes than those that pertain in

the military world.

37

• Design and construction. Commercial ships are, for the

most part, large steel boxes with relatively small and simple

propul-sion and navigation systems. Designing military ships

takes longer because of their high equipment density, the large

num-ber of sophisticated systems involved, and a desire to at

least match the current state of the art. Construction of

commercial ships is mostly a volume business that depends on

simple steel forming and welding processes repeated over and

over. The con-struction of warships involves the use of exotic

materials, the installation of large amounts of high-value,

sensitive equipment, and the satisfaction of more exacting

standards. The testing process for military ships is more

involved because it has to reflect the high technology and

technology density of the ships and take account of multiple

possibilities for mutual interference of advanced electronic

systems.

• Workforce character. In the United Kingdom, military ship-

building requires a much higher ratio of white- to blue-collar

workers than that found in commercial shipbuilding. This is

because military shipbuilding demands much more engineering

support, as well as the need to interact extensively with the gov-

ernment oversight team. Military shipbuilding also requires

more highly skilled and specialised workers. Such high

overhead and high skill base cannot be sustained by any yard

that expects to build typical commercial ships at competitive

prices.

3.5.3 Prospects for Market Entry an Integration

As suggested above, the United Kingdom would face strong

competi-tors in attempting to re-enter the commercial

shipbuilding market. Japan and South Korea dominate the

market for ships of low and moderate complexity, mostly cargo

ships and tankers of varying types. The European Union

dominates the market for more-complex ships such as

38

passenger vessels, although that market segment is also under

pressure from Asian shipbuilders. The global shipbuilding

market has for some years been characterised by excess

capacity, so profits have been low. A newcomer would face

formidable impediments to securing a meaningful market niche

in such an environment. Towards the latter half of 2003,

demands for certain ship types (mostly very large container

ships, bulk carriers, and liquefied natural gas [LNG] tankers)

suddenly soared, pressing the available builders and, we

surmise, increasing profits. The United Kingdom has not been

in a position to take advantage of this shift and cannot count on

it lasting for long. UK shipyards attempting to enter or re-enter

the commercial shipbuilding market would also have to find a

way to resolve all the workforce, process, and facility issues

discussed above in a niche that took advantage of their special

high-skill and high-complexity capabilities. Finally, the pound

has recently been strong against the dollar, which also works

against the United Kingdom‘s export interests. We thus find

prospects for re-entry of UK shipyards into the commercial

market to be, on the whole, daunting.

The military export market is small in value compared with the

commercial market. It nonetheless represents a tempting target

for a nation with a largely military industry that is attempting to

gain some ability to level the load over domestic military

production lulls. Here again, UK shipbuilders face strong

competitors in Germany and France, which together have more

than 60 percent of the military export market. The United

Kingdom certainly has a stronger indus-trial base to support

military sales than it does in the commercial arena, but the

match between most current UK military ship prod-ucts and

global demand is not a close one. The military export mar-ket is

largely a market for modestly priced frigates and small conven-

tionally powered attack submarines. It is not clear that a UK

39

shipyard could build a conventional submarine at a competitive

price; UK warships are, in general, too sophisticated and

expensive to make them interesting to potential importers.

Furthermore, export con-tracts often require that most ships in

an order be built in the importing country, thus limiting the

benefit such sales may have for the exporter‘s construction

workforce.

As mentioned above, should the United Kingdom attempt to re-

enter the commercial market, shipyards currently building

military ships would have to diversify into commercial

production. While some yards do have experience with naval

auxiliaries or recent com-mercial projects, the historical trend

has been more towards speciali-sation than integration of

commercial and military production. Inte-gration can, of course,

bring the benefits of military technological advances to

commercial construction, and the benefits of efficient

commercial processes can feed back to the military side.

However, most successful shipbuilders have found it difficult to

build both mili-tary and commercial ships, of any degree of

complexity, within the same operation. Certain Japanese yards

constitute a possible excep-tion, and their practices warrant

further investigation.

3.5.4 The Way Forward

While prospects for broadening UK shipyards‘ customer base

would appear to be poor, the shipbuilding industry is a volatile

one, and events could always break unexpectedly in the United

Kingdom‘s favour. Taking advantage of such opportunities

requires some prepa-ration, such as the development of less

expensive warship designs that reflect the needs of potential

buyers. Research and development directed towards a

generation-skipping commercial design or dra matic

technological advances in systems and materials could also be

fruitful.

40

Of course, development of new designs and technologies would

require investment on the part of shipbuilders and marine

equipment suppliers and potentially on the part of government,

if appropriate and if consistent with EU rules. It would require

investment, for example, in sustaining core design and

programme management skills through lulls in orders. These

investments would be risky, because the probabilities of payoff

would not be high, but externalities might accrue to domestic

military shipbuilding and to other UK industries.

This work could not have been undertaken without the

steadfast support and encouragement we received from Sir

Robert Walmsley, then Chief of Defence Procurement and

Chief Executive, DPA, and members of his staff. Many

individuals in the MOD provided their time, knowledge, and

information to help us perform the analyses discussed in this

report. Their names and contributions would fill several pages.

If we were to single out two persons who participated in and

supported this work in extraordinary ways, we would mention

our action officer Andy McClelland of the DPA and Robin

Boulby of the Future Aircraft Carrier programme‘s Integrated

Project Team. Their tireless efforts on our behalf are greatly

appreciated, along with their constructive comments on earlier

drafts.

We are also indebted to the UK, US, and EU shipyards that

par-ticipated in this study. Each gave us the opportunity to

discuss a broad range of issues with the people directly

involved. In addition, all the firms arranged for us to visit their

facilities. The firms and gov-ernment offices provided all the

data we requested in a timely man-ner.

We are indebted to Brien Alkire of RAND and Philip Koenig of

the Office of Naval Research for their formal review of the

41

document and the many improvements and suggestions they

made. Professor Thomas Lamb of the University of Michigan

participated in data collection and made several helpful

suggestions for the analysis— we thank him for his time and

help. We are additionally indebted to Joan Myers for her deft

assistance organising and formatting the many drafts.

42

PERTEMUAN 4

Introduction to Aircraft Stability

4.1 Pendahuluan


a. Aerodinamic Background

b. Static Longitudinal Stability and Control

c. Dynamical Equations of Motion

d. Dynamic Stability

e. Control of Aircraft Motions



memahami Aerodinamic Background, Static Longitudinal Stability

and Control, Dynamical Equations of Motion, Dynamic Stability,

Control of Aircraft Motions



menjelaskan Aerodinamic Background, Static Longitudinal Stability

and Control, Dynamical Equations of Motion, Dynamic Stability,

Control of Aircraft Motions



penilaian






4.5.1 Aerodynamic Controls

An aircraft typically has three aerodynamic controls, each

capable of producing moments about one of the three basic

axes. The elevator consists of a trailing-edge flap on the

43

horizontal tail (or the ability to change the incidence of the entire

tail). Elevator deflection is characterized by the deflection angle

δe. Elevator deflection is defined as positive when the trailing

edge rotates downward, so, for a configuration in which the tail

is aft of the vehicle center of mass, the control derivative

∂Mcg < 0

∂δe

The rudder consists of a trailing-edge flap on the vertical tail.

Rudder deflection is characterized by the deflection angle δr .

Rudder deflection is defined as positive when the trailing edge

rotates to the left, so the control derivative

∂Ncg < 0

∂δr

The ailerons consist of a pair of trailing-edge flaps, one on each

wing, designed to deflect differentially; i.e., when the left aileron

is rotated up, the right aileron will be rotated down, and vice

versa. Aileron deflection is characterized by the deflection angle

δa. Aileron deflection is defined as positive when the trailing

edge of the aileron on the right wing rotates up (and,

correspondingly, the trailing edge of the aileron on the left wing

rotates down), so the control derivative

∂Lcg > 0

∂δa

By vehicle symmetry, the elevator produces only pitching

moments, but there invariably is some cross-coupling of the

rudder and aileron controls; i.e., rudder deflection usually

produces some rolling moment and aileron deflection usually

produces some yawing moment.

44

4.5.2 Atmospheric Properties

Aerodynamic forces and moments are strongly dependent upon

the ambient density of the air at the altitude of flight. In order to

standardize performance calculations, standard values of

atmospheric properties have been developed, under the

assumptions that the atmosphere is static (i.e., no winds), that

atmospheric properties are a function only of altitude h, that the

temperature is given by a specified piecewise linear function of

altitude, and that the acceleration of gravity is constant

(technically requiring that properties be defined as functions of

geopotential altitude. Tables for the properties of the Standard

Atmosphere, in both SI and British Gravitational units, are given

on the following pages.

4.5.3 Aerodynamic Background

Aerodynamic Properties of Airfoils

For low speeds (i.e., Mach numbers M << 1), and at high

Reynolds numbers Re = V c/ν >> 1, the results of thin-airfoil

theory predict the lifting properties of airfoils quite accurately for

angles of attack not too near the stall. Thin-airfoil theory

predicts a linear relationship between the section lift coefficient

and the angle of attack α of the form

cℓ = a0 (α − α0)

as shown in Fig. 2.3. The theory also predicts the value of the

lift-curve slope

a0 = ∂cℓ = 2π

∂α

Thickness effects (not accounted for in thin-airfoil theory) tend

to increase the value of a0, while viscous effects (also

neglected in the theory) tend to decrease the value of a0. The

value of a0 for realistic conditions is, as a result of these

counter-balancing effects, remarkably close to 2π for most

practical airfoil shapes at the high Reynolds numbers of

practical flight.

45

The angle α0 is called the angle for zero lift , and is a function

only of the shape of the camber line. Increasing (conventional,

sub-sonic) camber makes the angle for zero lift α0 increasingly

negative. For camber lines of a given family (i.e., shape), the

angle for zero lift is very nearly proportional to the magnitude of

camber – i.e., to the maximum deviation of the camber line from

the chord line.

A second important result from thin-airfoil theory concerns the

location of the aerodynamic center . The aerodynamic center of

an airfoil is the point about which the pitching moment, due to

the distribution of aerodynamic forces acting on the airfoil

surface, is independent of the angle of attack. Thin-airfoil theory

tells us that the aerodynamic center is located on the chord line,

one quarter of the way from the leading to the trailing edge –

the so-called quarter-chord point. The value of the pitching

moment about the aerodynamic center can also be determined

from thin-airfoil theory, but requires a detailed calculation for

each specific shape of camber line. Here, we simply note that,

for a given shape of camber line the pitching moment about the

aerodynamic center is proportional to the amplitude of the

camber, and generally is negative for conventional subsonic

(concave down) camber shapes.

It is worth emphasizing that thin-airfoil theory neglects the

effects of viscosity and, therefore, cannot predict the behavior

of airfoil stall, which is due to boundary layer separation at

high angles of attack. Nevertheless, for the angles of attack

usually encountered in controlled flight, it provides a very

useful approximation for the lift.

46

Airfoil section lift coefficient as a function of angle of attack

Airfoil lift and moment coefficients as a function of angle of

attack; wind tunnel data for two cambered airfoil sections

Finally, wind tunnel data for two cambered airfoil sections are

presented in Fig. 2.4. Both airfoils have the same thickness

distributions and camber line shapes, but the airfoil on the

right has twice as much camber as the one on the left

(corresponding to 4 per cent chord, versus 2 per cent for the

airfoil on the left). The several curves correspond to Reynolds

numbers ranging from Re = 3 × 106 to Re = 9 ×106, with the

curves having larger values of cℓmax corresponding to the

higher Reynolds numbers. The outlying curves in the plot on

47

the right correspond to data taken with a 20 per cent chord

split flap deflected (and are not of interest here).

Note that these data are generally consistent with the results

of thin-airfoil theory. In particular:

1. The lift-curve slopes are within about 95 per cent of the

value of a0 = 2π over a significant range of angles of

attack. Note that the angles of attack in Fig. 2.4 are in

degrees, whereas the a0 = 2π is per radian;

2. The angle for zero lift of the section having the larger

camber is approximately twice that of the section having

the smaller camber; and

3. The moment coefficients measured about the quarter-

chord point are very nearly independent of angle of attack,

and are roughly twice as large for the airfoil having the

larger camber.

Aerodynamic properties of finite wings

The vortex structures trailing downstream of a finite wing

produce an induced downwash field near the wing which can

be characterized by an induced angle of attack

For a straight (un-swept) wing with an elliptical spanwise

loading, lifting-line theory predicts that the induced angle of

attack αi is constant across the span of the wing, and the

efficiency factor e = 1.0. For non-elliptical span loadings, e <

1.0, but for most practical wings αi is still nearly constant

across the span. Thus, for a finite wing lifting-line theory

predicts that

48

where a0 is the wing section lift-curve slope and α0 is the angle

for zero lift of the section. Substituting Eq. (2.16) and solving

for the lift coefficient gives

whence the wing lift-curve slope is given by

Lifting-line theory is asymptotically correct in the limit of large

aspect ratio, so, in principle, Eq. (2.18) is valid only in the limit

as AR → ∞. At the same time, slender-body theory is valid in

the limit of vanishingly small aspect ratio, and it predicts,

independently of planform shape, that the lift-curve slope is

a = πAR

2

Note that this is one-half the value predicted by the limit of the

lifting-line result, Eq. (2.19), as the aspect ratio goes to zero.

We can construct a single empirical formula that contains the

correct limits for both large and small aspect ratio of the form

49

PERTEMUAN 5

Konsep Struktur Fighter

5.1 Pendahuluan


a. Struktur Analysis

b. Strukrur Design & Payload Design



memahami Struktur Analysis, Strukrur Design & Payload Design



menjelaskan Struktur Analysis dan Strukrur Design & Payload

Design



penilaian






5.5.1 Struktur Analysis

Bidang Kompetensi

• Stress Analysis

• Aircraft Load Analysis

• Aerolasticity

• Fatique & Fracture Mechanics

• Weight and Balance

50

Stress Analysis

• Finite Element Modeling

• Stress Analysis

• Composite Stress Analysis

• Static Stability Analysis

• Structure Design Optimization

• Static Test Requirement and Result Analysis

• Bird Impact Analysis & Test

• Certification Plan

• Aircraft Crashworthiness

Nastran, Patran and our in house programs are widely used in

Structural Stress Analysis

Aircraft Load Analysis

• Flight Load Analysis

• Ground Load Analysis

• Emergency Load Analysis

• Miscellaneous Load Analysis

• Aircraft Component Load Analysis

• Load Analysis Software Development

• In-flight Load Measurement

• Aircraft Operating Limitation

• Load Analysis Cerftification

51

• Post-TC Maintenance Support

Aeroelastic and Dynamic Analysis

• Structural Dynamic Analysis

• Divergence & Control Reversal Analysis

• Usteady Aerodynamic & Flutter Analysis

• Propeller Aerodynamic Derivative 7 Whirl Flutter Analysis

• Dynamic Gust Analysis

• Landing Impact Analysis

• Shimmy Analysis

• Ground Vibration Test

• Flight Flutter Test

• Aeroelastic Certification

• Post-TC Maintenance Support

52

Fatique and Fracture Mechanics

• Fatique Analysis

• Damage Tolerance Analysis

• Fatique Certification Plan

• Structure Repair Manual

• Aging Aircraft Evaluation

• Load Spectra Development

• In-sevice Fatique Load Measurement

• Fatique & Damage Tolerance Test

• Inspection Program Development

• Principle Structure Elemnt Selection

5.5.2 Structure & Payload Design

Structure Design

• Metallic Part Design

• Composite Part Design

•

• Digital Part List (DPL) Generation

53

Structure and System Integration

• Catia Digital Mock Up Creation

• Interface Design and Lay Out

• Design Installation of Customer Option Components

Sustaining Program Engineering Support

• Existing Aircraft Program Modification

• Manual Drafting and Drawing Updating

• Manual Drawing to CATIA Modeling/Conversion

• CADDS5 Drawing/ Model to CATIA Modeling/ Concersion

Payloads Design

54

Konsep Teknologi Struktur Fighter

• Structure Design Concept

\

56

Case Study of The Wing Layout

Case Study of Wing-Fuselage Fitting

57

Trend of the Material Technology

59

PERTEMUAN 6

INTRODOUCTION TO FIGHTER

6.1 Pendahuluan


a. Kompetensi Dalam Pengembangan Pesawat Terbang

b. Airplane Integration

c. History Of Jet Fighter



memahami Kompetensi Dalam Pengembangan Pesawat Terbang,

Airplane Integration, History Of Jet Fighter



menjelaskan Kompetensi Dalam Pengembangan Pesawat Terbang,

Airplane Integration, History Of Jet Fighter



penilaian





60


6.5.1 Kompetensi Dalam Pengembangan Pesawat Terbang

• Flight Physics: Aerodynamics, A/C Performance, S&C ,

Propulsion Analysis, dst.

• Flight Structure: Weight, Load, Stress Analysis,

Aeroelasticity, Fatigue & damage Tolerance, Payload

Design, Structure Design

• Flight System: Avionik, Flight Control, Propulsion,

Subsystem, System Design & Installation

• System Engineering: Risk Management, RM&S, Test &

Evaluation, Certification Management, System Engineering

• Management

Evolution of an Airplane (The Role of Technology Group)

61

Evolution of an Airplane (The Role of Aircraft Design

Group)

Airplane Program Phasing

62

Aspek-Aspek dalam Perancangan Pesawat Terbang

Different Disciplines Different Dream

6.5.2 Airplane Integration

63

Transport Aircraft Design Objectives and Constraints

Comparison Of Commercial And Military Aircraft Development

History Of Jet Fighter

68

PERTEMUAN 7

Propulsion

7.1 Pendahuluan


a. Propulsion Analysis

b. Propulsion Integration



memahami Propulsion Analysis, Propulsion Integration



menjelaskan Propulsion Analysis, Propulsion Integration



penilaian






7.5.1 Propulsion analysis

Propulsion Analysis includes air induction system design,

installed engine performance analysis, and aircraft after-body

design

69

Functional Interface

Sizing & Design

70

Inlet Trade Study

7.5.2 Propulsion Integration

Propulsion Integration Overview

72

System Requirement Analysis

73

OTS System Review

74

System Development

77

PERTEMUAN 8

UTS

78

PERTEMUAN 9

Structural, Design and Analysis

9.1 Pendahuluan


a. State of the Art

b. The Method

c. Generation of efficient design alternatives



memahami State of the Art, The Method, Generation of efficient

design alternatives



menjelaskan State of the Art, The Method, Generation of efficient

design alternatives



penilaian






9.5.1 State of the Art

Maritime Safety

As indicated by the IMO (2002) and the research

community (Cho et al. 2006, Moore et al. 2009), to

correctly undertake the establishment of maritime safety

79

criteria, it is necessary to consider the maritime

stakeholders and their preferences. Freeman (1984)

describes stakeholders as actors whose interests in a

system need to be addressed, while Roy (1996) notes that

stakeholders demonstrate preferences towards options.

would arrive by a pipeline. The project, after many years of

planning, infamously failed as a result of the intensive

public outcry for the protection of the environment.

Counter-initiatives were strictly conducted in Croatia, and

nothing similar occurred in any other country with a

shoreline touching the Adriatic. On the other hand, no

specific measures were taken by the government or

industrial stakeholders to implement safer operations

beyond the minimum requirements of industry standards

and international conventions. The irony of such an

outcome is in the fact that during the time of the planning

of the project, and still today, a very intensive import traffic

of Arabian oil was conducted at the harbour of Trieste,

Italy, also located in the North Adriatic. And no protests

were heard. We can only wonder whether the outcome

would have been different if the government and industry

had had the capacity and willingness to implement e.g.

ships with improved crashworthiness.

related to a system. In that sense, we can also observe

the maritime stakeholders and their preferences regarding

safety. All maritime stakeholders consider safety

extensively in their activities, but they obviously do not

possess the same preferences concerning it, e.g. how

much is to be invested into averting a life lost or a ton of

oil spilled.

Not everybody benefits from safety equally, and nor does

everybody have a chance to manage safety in the

80

maritime industry. For example, ship owners manage

safety directly through operations, while the yard has the

responsibility to meet the minimum requirements in

designing and building a ‗safe‘ product. The minimum

requirements are elicited, on the other hand, through a

stakeholder dialogue, which includes the industry and the

regulators with the mandate of serving society overall.

Because of their roles in society, the risks and profits they

face differ significantly, and so do their preferences. This

inevitably leads to a different ranking of priorities.

Bennett (2001) and Pöyhönen (2000) describe typical

examples of these preferences. Their findings could be

summed up as follows. The commercial aspects are

primarily considered relevant by the industry, while society

and individual professionals like seamen are more

interested in improving safety but without any great

willingness to bear the economic burden.

A number of studies seek to establish criteria that follow

these findings (Vatn 1998, Melchers 2001, Aven 2003). By

formally establishing the maximum tolerance of risk for the

public, i.e. the minimum safety requirements, and the

maximum for efficient investments into safety, a so-called

‗As Low As Reasonably Possible‘ or ALARP region of

relevant strategies for safety management can be

established; see Figure 2.

The determination of the maximum risk tolerance and of

the maximum for efficient investments differs among the

studies. Ditlevsen (2003) employs profiling of the nature of

maritime risk, i.e. critical intolerance of high-consequence

accidents that possess low occurrence, to establish the

minimum acceptable levels of safety. Skjong and Ronold

(1998), on the other hand, use a Life Quality Index (Lind

81

1996) to establish how much should be maximally

invested into the prevention of the loss of life. A so-called

‗upper bound criterion‘ of Implied Cost of Averted Fatality,

or ICAF threshold, is defined on the premise of the

economic activity of a life lost. Depending on the area of

operations observed, or persons‘ origin, this value ranges

between 300 k€ and about 3 M€. Should the investment

into safety be efficient, the CAF, or the Cost to Avert the

Fatality, defined as the ratio

ALARP – ‗as low as reasonably practical‘ probabilities (Melchers

2001) with typical risk acceptance frequency for the number of

fatalities (Pedersen 2010)

between the costs of investment in reducing the risk of

loss of life and the expected reduction in loss of life, needs

to be smaller than the threshold value of ICAF. Ditlevsen

and Friis-Hansen (2003), combining the works above,

establish a decision criterion for the acceptance of risk by

the public to determine the threshold of the maximum

amount to be invested into the aversion of environmental

82

loss. The criterion is based on the balance between the

benefits of maritime transport to the public and the risks it

brings to the public. Following this work, and the work of

Skjong and Vanem (2005), the IMO (2008) established the

threshold of Cost to Avert a Tonne of Spillage, or

CATSthr, at about 50 k€. CATS2 itself is established

analogously to CAF.

ICAF and CATSthr are very straightforward values for

determining the efficiency of the investments being

considered, but they lack the capacity to distinguish

between low and high risks, as well as between the

particular preferences of maritime stakeholders, which are

relevant from the point of view of this study. They lack the

capacity to determine the optimum amount of investments

into safety, i.e. that the design alternative approaching the

threshold would be considered optimal. Furthermore, the

values of CAF and CATS should not be used as criteria,

i.e. the less the better, as they can produce very

misleading figures, where their minima can be found e.g.

for very ‗cheap‘ alternatives with a minimum of risk

reduction. The opposite, i.e. to maximise CAF and CATS,

is irrational. ICAF and CATSthr are also determined in

general, so they lack the sensitivity to capture the aspects

of a particular ship project. Thus, they can be misleading if

applied alone.

As an alternative, Rosqvist and Tuominen (2004) and

French et al. (2005) consider a multi-attribute decision-

making framework. Assuming full compensation for the

costs and benefits of safety investments amongst the

stakeholders, they establish a more rational framework to

determine the optimal amount of investment. No firm or

predetermined thresholds are implied, as the selection is

83

based strictly on the preferences of stakeholders. On this

basis, and on the IMO‘s (IMO 2002) recommendation for

the fair treatment of stakeholders‘ preferences, Rosqvist

(2003) provides a selection criterion where the optimum of

safety investments is found for the design alternative with

the fairest distribution of the corresponding risks between

the stakeholders.

The validity of the assumption of full compensation

amongst stakeholders is reasonable if one considers a

very broad domain of stakeholders. Enough stakeholders

make up the total economics of maritime transport and are

thus part of the fully compensated system. Such a

situation then easily correlates with safety as defined in

international conventions, industry standards, and

practices, e.g. when considering the updating of statutory

rules. Within a narrower context, e.g. the structural design

of a ship, the validity of the assumption about full

compensation amongst stakeholders comes in question.

The number of stakeholders involved, i.e. those sensitive

to the changes in structural design, is smaller. Obviously,

these represent only a part of the total economics, and the

assumption of full compensation can no longer be

guaranteed. Hence, an alternative approach should be

considered.

Game Theory

Vincent and Grantham (1981) show how a design process

can be described as a decision-making problem.

Designing to satisfy the preferences of multiple

stakeholders can then be seen as a group decision-

making problem, where each stakeholder is treated as a

decision maker.

84

Differing preferences lead to competitive relationships

between stakeholders (Håkansson and Henders 1990). In

such relationships stakeholders are not willing to renounce

any of their benefits as they try to maximise them

independently (Duetsch 1949, Wilkinson and Young

1994). Such a decision-making problem is formalised

effectively through the theory of mathematical games, or

Game Theory (v Neumann and Morgenstern 1944,

Meyerson 1991, Keeney and Raiffa 1977). Two types of

games can be distinguished. A static game describes a

situation in which each stakeholder makes a choice from a

fixed set of strategies, and where this set does not depend

on the choices made by other stakeholders. A dynamic

game, on the other hand, possesses varying sets of

strategies, which depend on the choices made. A dynamic

game obviously assumes that the choices are made at

least twice, and thus it can, in a simplified manner, be

understood as a series of static games.

According to the above definition, ship design is a

dynamic process. Thus, utilising a dynamic game would

be the most appropriate way to map it and thus solve it.

However, ship design is also complex, and the elicitation

of the available strategies and consequences of the

choices made cannot be defined explicitly. Similarly to the

game of chess, it cannot be mapped, but it can be tackled.

Maritime stakeholders, through preferences, trade off

between the costs and benefits they face with a ship either

in production or in operation. In the case of safety, this

refers to the cost-effectiveness of any risk control option

that is considered. Therefore, a single static game can be

derived in such a way that it models the cost-effectiveness

of the alternatives and allows the selection of one option

85

that optimally satisfies all stakeholder preferences, as

shown in Figure 2.

The ‗dynamic‘ part of the design decision making can be

approximated with design optimization; again, see Figure

2. If we are aiming to select the best design alternative,

then the alternatives that are considered should be good

solutions.

Design decision-making process modelled as a) a dynamic and b) a static

mathematical game with the Nash Equilibrium marked.

Speaking in terms of multi-objective optimization, design

alternatives considered for selection through a static game

should be non-dominated solutions of the optimization

problem. The non-dominated solutions, or Pareto optima,

possess attributes that are not entirely outranked

(dominated) by any other alternative under consideration

(Pareto 1896). Extending this to the utilities of

stakeholders, the non-dominated design alternatives

effectively become compromise solutions between

stakeholder preferences. In terms of group decision

making, they are collectively stable solutions (Rao et al.

1997), i.e. their attributes and utilities cannot all be

simultaneously improved by any alterations in order to

reach a new feasible design.

86

Depending on the nature of the game, a static game

possesses several well-known solutions, e.g. Min-Max,

Bayesian, etc. For the competitive games, the classic

solution of Nash (Nash 1951), better known as Nash

Equilibrium, is considered often. It is defined as the

outcome of the optimal choice of strategies of

stakeholders in their response to the optimal choices of

others. Such a solution can be defined as ‗individually

stable‘ (Rao et al. 1997), referring to the fact that no

unilateral decision by any stakeholder will result in higher

benefits for that stakeholder than at the Nash Equilibrium.

In this case, the Nash Equilibrium will yield an alternative

that optimally distributes the benefits and costs related to

the risk reduction amongst the stakeholders. However,

Dubey (1986) shows that the Nash Equilibrium of a static

competitive game will probably be a non-efficient solution.

Saksala (2005) vividly depicted this ‗anomaly3‘ for a

number of cases in structural design. Such an outcome is

then irrational with respect to the considerations of ship

design in general, as another alternative can provide more

benefits to all stakeholders than the Nash Equilibrium.

Special care should thus be taken when considering the

application of Nash Equilibrium.

9.5.2 Scope of the work

Based on the indicated research gap in the four observed

research areas, i.e. maritime safety, Game Theory, ship

structural optimization for multiple objectives, and

collisions and grounding of ships, Figure 4 symbolically

indicates th e scope of this thesis. We can notice that thes

e contributions are principally located at the interfaces of

the four observed research areas, and can be classified

87

into: i) design selection; ii) GA optimization; iii)

crashworthiness optimization, and iv) safe ship structures.

Game Theory provides a set of concepts to address

decision problems involving multiple stakeholders. In

cases where full co mpensation of costs and benefits

amongst the stakeholders cannot be guaranteed, an

economically stable solution can still be provided usin g

the theory. This solution should be fair, and, unlike the

ICAF and CATSthr criteria, it should distinguish between

design alternatives with strong safety improvements and

those with low safety improvements.

The thesis thus adopts the concept of static competitiv e

games to outline a novel design selection criterion, the

Competitive Optimum.

. Scope of the work: the basic research fields (in white) and contributions (in

grey)

For the Competitive Optimum three fundamental

conditions of selection will suffice, i.e. i) non-dominance, ii)

efficiency, and iii) maximal stakeholder satisfaction in

competitive relationships (MaSSCoR). The latter ensures

fairness.

88

MaSSCoR is based on a Nash Equilibrium solution for

static games, which provides the fairest distribution of

benefits amongst stakeholders in competitive

relationships. But since the Nash Equilibrium of a general

static game can be dominated, and hence inefficient, a

special static game is constructed assuring that the Nash

Equilibrium identifies an alternative that suffices for the

first two conditions of selection. To establish this game, we

apply multi-objective structural optimization.

Optimization allows the systematic exploration of the

design possibilities, thus providing reassurance that the

optimal alternatives that are attained are efficient. Since

classical optimization methods lack the capacity to solve

practical large-scale multi-objective problems, and the

current GA optimization also demands a large number of

functional evaluations, the thesis proposes a special GA

based on vectorization in order to enhance the

optimization process. This GA quickens the optimization

by converting all design constraints into objectives,

providing the necessary advantages in solving problems

such as the optimization of ship crashworthiness. A

systematic study is conducted on the effects of

vectorization, i.e. constraints are not only converted to

objectives, but also grouped and partially grouped to

provide strategies for approaching large-scale and time-

expensive problems. In that sense a novel ‗two-step‘

optimization procedure is proposed.

Two case studies are conducted to illustrate the

theoretical contributions that are addressed. The study on

the design of a safe double bottom for a Ro-Pax ship with

regard to grounding accidents features applications of

multi-stakeholder decision making and selection of the

89

double-bottom design that provides the best satisfaction of

stakeholders‘ preferences. Two stakeholders are

considered, the yard and the ship owner.

The study on the design of a safe tanker side structure

with respect to collision accidents, similarly to the Ro-Pax

study, features multi-stakeholder decision-making analysis

and design selection using the proposed criterion. The

study also features multi-objective optimization of the mid-

ship structure with the proposed GA to create the efficient

design alternative from which the optimal alternative can

finally be selected. The tanker is concurrently optimised

for minimum weight and for maximum crashworthiness.

Four stakeholders are identified as relevant decision

makers, i.e. the yard, the ship owner, the cargo receiver,

and the public. Risk analysis is performed, and the risk is

defined for each of the efficient alternatives generated and

for each of the four stakeholders. The related costs

resulting from an increase in crashworthiness are also

defined.

9.5.3 Limitations

The results of this thesis should be observed in the light of

the assumptions that are considered, following the desire

to focus on the early stages of the design of ship

structures.

The Competitive Optimum criterion is based on the

concept of Nash Equilibrium, which guarantees fairness

towards stakeholder preferences in design selection, and

carries the limitation that the list of assumed attributes is

not exhaustive. Furthermore, a fundamental element of

the Competitive Optimum criterion is the shared

perception of the ‗Ideal‘ among the stakeholders. The

Competitive Optimum solution will thus hold only as long

90

as all stakeholders perceive all attributes of the ‗Ideal‘

design alternative as a maximal fulfilment of their

preferences.

The stakeholder are assumed to be purely competitive,

while their preferences are a product of perfect rational

thinking with neutral attitude towards risk. This means that

a stakeholder will base decisions purely on the expected

value of an attribute. This principally holds for institutional

and industrial stakeholders, while the public is typically

more risk averse, i.e. the adverse expected attribute

values are progressively less preferred.

In this thesis, however, the public is considered

analogically to the institutional stakeholders, since their

interests are described in terms of explicit monetary

figures which is assumed to exclude emotional aspects

that bring front already mentioned risk aversion.

Risk is thus considered equivalent to expected utility6, and

is calculated explicitly following the utility theory (v

Neumann and Morgenstern 1944) as a value under

uncertainty, i.e. it is a product of consequence costs and

the probability that this consequence would occur.

The proposed GA algorithm is based on the conversion of

design constraints into objectives, i.e. vectorization. Two

types of vectorization are studied in the thesis, absolute

and Heaviside. For the optimization of tanker structures,

Heaviside vectorization was applied.

The ‗two-step‘ optimization procedure is devised on the

premise that the process of multi-objective optimization

can be split into two phases if the following two types of

objectives exist: i) easy to evaluate but difficult to optimise,

e.g. the weight of the ship structure, and ii) difficult to

91

evaluate, i.e. time-expensive but easy to optimise, e.g.

ship crashworthiness.

Independently of the fact that the proposed GA algorithm

with vectorization, through the ‗two-step‘ procedure,

enhances the optimization of large-scale problems, the

evaluation of crashworthiness during the optimization

needs to be rapid. Thus, it is evaluated for a single critical

collision scenario only. This is a major assumption, which

necessitates further validation, and for this reason the

practical outcome of the tanker case study is to be treated

accordingly.

9.5.4 The method

There are two most important parts of the proposed

design method. The

first is the generation of safe design alternatives, and the

second is the

selection of ‗the safe‘ alternative. The term ‗the safest‘ is

deliberately avoided. It strongly impedes other

characteristics of such design alternatives, as it is clearly

the one with the maximum risk reduction, but

not necessarily the one with the best distribution of costs

and benefits

amongst the stakeholders related to this risk reduction.

The method, on the other hand, results in exactly such an

alternative.

92

Scheme of the activities in the proposed methodology: leading from an

adverse event scenario, e.g. collision or grounding, new optimal design

alternatives are generated through multi-objective optimization; they are

evaluated for safety (risk analysis) and from the commercial aspect and,

finally, an alternative is selected following the multi-stakeholder decision

making and the Competitive Optimum criterion.

As mentioned, the method focuses on the structural

design of the ship, providing support to designers in

determining the best parameters of a structure they

design. It is structured on a cycle, shown in Figure 5

above, that is initiated by the analysis of the casualty that

is to be mitigated by improving safety. In cases where

collisions or grounding are to be mitigated, the ship

structure will be optimised for crashworthiness, though

without forgetting the commercial aspects of design

objectives, e.g. the weight of the ship hull. Following up on

this multi-objective optimization, the safe structures that

are generated need to be checked for stakeholder

preferences, i.e. the costs and benefits of safety

investments need to be evaluated exactly. This demands

both risk and economic analysis of the impact of the

increased crashworthiness. Finally, a safe ship structure

can be identified. As with any other method used in ship

design, this process can be repeated as many times as is

found necessary by the designers.

93

PERTEMUAN 10

Marine Propulsion

10.1 Pendahuluan


a. Propulsion sytems

b. Enviromental effects

c. Matching engines and watercrafts. Ship resistance

d. Underwater propulsion



memahami Propulsion sytems,Enviromental effects, Matching

engines and watercrafts. Ship resistance,Underwater propulsion



menjelaskan Propulsion sytems,Enviromental effects, Matching

engines and watercrafts. Ship resistance,Underwater propulsion



penilaian





94


10.5.1 Propulsion Systems

A propulsion system consists of three parts: an energy

source (carried aboard as animal or fuel energy, or

collected from outside as wind or solar power), an engine

that transforms it to a mechanical form, and the propulsor or

thruster (that pushes the surrounding water backwards).

Some watercraft propulsion systems: a) Oar layout in a Greek trireme. b)

Amerigo Vespucci, full-rigged ship. c) Paddle-wheel boat (diesel powered). d)

Engine room (coloured) in Queen Mary. e) Modern integrated propeller and

rudder system. f) Water-jet propulsion, showing reverse thrust. g) Hydrofoils are

usually waterjet-propelled. h) Seven-bladed screw submarine propeller. i)

Battery-powered diver propulsion device.

Types A brief grouping may be:

• Animal power, usually human rowing (Fig. 1a), but horse-

driven boats have been used (both towing with ropes from

the shore in canals, and turning a on a treadmill linked to a

propeller, aboard).

http://en.wikipedia.org/wiki/Trireme

http://en.wikipedia.org/wiki/Full_rigged_ship

http://en.wikipedia.org/wiki/Full_rigged_ship

http://en.wikipedia.org/wiki/Paddle_steamer

http://www.queenmarycruises.net/rms-queen-mary/

http://www.rolls-royce.com/marine/products/propulsors/promas/

http://www.rolls-royce.com/marine/products/propulsors/promas/

http://en.wikipedia.org/wiki/Pump-jet

http://en.wikipedia.org/wiki/Hydrofoil

http://web.mst.edu/~rogersda/military_service/subs.htm

http://en.wikipedia.org/wiki/Diver_propulsion_vehicle

95

• Environmental power-gathering: wind power (sails), solar

power (photovoltaic). Electrical propulsion in marine

engineering refers to electric-motor-driven propellers, with

electricity produced by heat engines, and not to direct

electric sources, like batteries or solar panels, used in

some small boats, and most small underwater vessels.

• Chemical fuels carried aboard, usually a petroleum-

derivative liquid-fuel, taking advantage of the surrounding

oxidiser in the air. Marine diesel is by far the most used

fuel.

• Nuclear fuel, only used in nuclear submarines, using

highly enriched fuel (>20 % U-235) in fission-reactors,

usually of pressurised-water type (PWR), always through

steam turbines (they are similar to external combustion

engines).nergy source

The first vessels might surely have been propelled by hand

work, but it was obvious that wind has an important

entrainment effect, and the larger the frontal are the larger

the push, what originated the sail. There is evidence of

sailing boats and wooden oars in the Middle East dating

from 5000 BCE, and, in ancient Egypt by 3000 BCE, the

Nile was the main transport route, taking advantage of the

water current to go downstream, and of the prevailing

Northern winds to go upstream.

Sailing (other than downwind) requires great expertise in

varying wind and sea conditions, sometimes with

extraordinary insight (e.g. how to come back to port): both

pioneers in the Age of Discovery, Columbus in the Atlantic

and Urdaneta in the Pacific, made use of the Easterly winds

in low latitudes (Trade winds), and of the Westerly winds in

96

mid latitudes, together with the general ocean circulation

circuits (clockwise in the North hemisphere), to link distant-

continent populations and establish permanent trade

routes.

Most watercrafts (as for any other type of land, air, or space

vehicle) are presently powered by a liquid fuel stored

aboard, and a heat engine that converts the chemical

energy of the combustion of that fuel with an oxidiser, to the

mechanical energy needed to actually perform the

propulsion work. Hence, to this last respect, propulsion is

always a mechanical effect; however, mechanical

propulsion usually refers to engine-propelled vehicles, in

this case vessels, leaving aside manual (rowing) and wind

(sailing).

Types of engines

A brief grouping, more or less in chronological order,

including rowing and sailing, may be:

• Mechanical transmission from energy source to

thruster, e.g. from animal power to oars or wheels.

• Sailing, i.e. wind power propulsion acting on extended

surfaces (sails).

• Steam engine, an external combustion engine,

working in a Rankine cycle, with water as working

fluid, used in practically all ships in the 19th century,

initially with reciprocating pistons and later with

turbines (the first in 1897 with the Turbinia steamer),

and on a few vessels since then (in some very large

ships, and in nuclear submarines). The name of steam

ships are often prefixed with SS.

https://en.wikipedia.org/wiki/Rowing

https://en.wikipedia.org/wiki/Sailing

http://en.wikipedia.org/wiki/Steamship

http://webserver.dmt.upm.es/~isidoro/bk3/c17/Power.pdf

http://en.wikipedia.org/wiki/Turbinia

97

• Diesel engine, an internal combustion engine (ICE),

working in a Diesel cycle, using marine diesel or

heavy fuel oil, and used in most ships since 1930s.

also known as motor ships. Diesel engines were

limited in power for many decades, but nowadays

there are no limit in practice, with MAN/B&W and

Wärtsilä-Sulzer as the major engine manufacturers.

The name of motor ships are often prefixed with MS.

• Gas turbine, an internal combustion engine (ICE),

working in a Brayton cycle, derived from aviation

turbines, able to burn marine diesel, kerosene, or jet

fuel, are used in some fast ships (e.g. hydrofoils),

warships (for quick action), and large cruisers. The

first passenger ferry to use a gas turbine was the GTS

Finnjet, built in 1977; four years later, diesel engines

were added to decrease fuel expense, becoming the

first ship with a combined diesel-electric and gas

(CODAG) propulsion.

• Dual fuel engines, like the LNG engine, an internal

combustion engine working in a Diesel cycle, using

liquefied natural gas (LNG) as main fuel, sometimes

working in dual-fuel mode with partial marine-diesel

injection.

• Gasoline engines (ICE), used in small outboard

motors. Electric motors, which may be powered by:

o Electrical batteries, like in model ships and

submarines.

o Diesel engines. This combination of a sizeable

power source (ICE) driving an electrical generator,

with a flexible electrical connection to the electrical

motors driving the

propellers, is very convenient in spite of its extra

cost. Most large ships, particularly cruisers, use

http://en.wikipedia.org/wiki/Marine_diesel_engine#Reciprocating_diesel_engines

http://en.wikipedia.org/wiki/MAN_Diesel

http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4

http://en.wikipedia.org/wiki/Sulzer_(manufacturer)

https://en.wikipedia.org/wiki/Motor_ship

http://en.wikipedia.org/wiki/Gas_turbines#Marine_applications

https://en.wikipedia.org/wiki/Combined_diesel_and_gas

http://en.wikipedia.org/wiki/Marine_diesel_engine#LNG_Engines

http://en.wikipedia.org/wiki/Outboard_motor

http://en.wikipedia.org/wiki/Outboard_motor

https://en.wikipedia.org/wiki/Cruise_ships

98

electric motors in pods called azimuth thrusters

underneath to allow for 360° rotation, making the

ships far more manoeuvrable.

o Photovoltaic panels (only able to propel small

ships).

o Fuel cells, first used as air-independent propulsion

(AIP) in German Type 212 submarines since

1998, based on proton exchange membrane fuel

cells (PEMFC) of around 250 kW in total. Other

PEM-FC are used in auxiliary power units on

board ships, and more powerful molten carbonate

(MCFC) and solid oxide (SOFC) high-temperature

fuel cells are being considered for general and

especial ship propulsion (e.g. hydrogen fuelled

ships), in combination with some heat-recovery

bottom cycle, enlarging the hybrid engine type of

solutions (the first hybrid propulsion was sailing

and steam, followed by the diesel-electric

submarine, and CODAG combinations).

The first machine use for mechanical propulsion (on land

and on water) was the steam engine which, after some

trials as early as 1770, took over in 1815 with the first

crossing of the English Channel by the steamship Élise.

The first thruster used was the paddle wheel, where a

number of paddles are set around the periphery of a

partially submerged wheel. The first screw-driven ship was

Stevens' Little Juliana, in 1811, which was the first ferry,

crossing the Hudson river. In 1880, the American

passenger steamer Columbia became the first ship to utilize

incandescent light bulbs, powered by a dynamo; this was

the first application of incandescent lighting, before Edison's

https://en.wikipedia.org/wiki/Azimuth_thruster

https://en.wikipedia.org/wiki/Electric_boat

https://en.wikipedia.org/wiki/Fuel_cell

https://en.wikipedia.org/wiki/Type_212_submarine

https://en.wikipedia.org/wiki/Hydrogen_ship

https://en.wikipedia.org/wiki/Hydrogen_ship

http://en.wikipedia.org/wiki/Steam_power

http://en.wikipedia.org/wiki/Steam_ship_%C3%89lise

http://en.wikipedia.org/wiki/Steam_ship_%C3%89lise

http://en.wikipedia.org/wiki/Paddle_steamer

http://en.wikipedia.org/wiki/John_Stevens_(inventor)

http://en.wikipedia.org/wiki/Ferry

http://en.wikipedia.org/wiki/Ferry

http://en.wikipedia.org/wiki/SS_Columbia_(1880)

http://en.wikipedia.org/wiki/Incandescent_light_bulb

http://en.wikipedia.org/wiki/Dynamo

http://en.wikipedia.org/wiki/Thomas_edison

99

first public power station in 1882, and soon after Edison

mastered the technology in his lab in 1878.

The main engine sits in the engine room, one of the largest

and more complex ship compartments, and the noisier (Fig.

2b). It is usually located at the aft bottom of the ship, to

minimise the shaft length to the propellers (at the stern),

though the increased use of diesel-electric propulsion

systems has released this constrain. In large ships there

are several engine rooms and engine-ancillary rooms

World's largest diesel engine, RTA96-C. b) A ship's engine room.

As an example of changing times in marine propulsion,

consider the two cruisers QM and QM2. RMS Queen Mary

was a steamer cruise of 2139 pax, built in 1936 and retired in

1967; its propulsion system delivered 120 MW (for propulsion

and hotel) from 24 Yarrow boilers that fed 4 Parson turbines,

each linked with a shaft to a screw propeller, with a service

speed of 15 m/s. RMS Queen Mary 2, built in 2003, is a part-

time cruiser and transatlantic ocean liner (the only one in

service, between Southampton and New York), of 2620 pax.

To its 117 MW of total installed power contribute four diesel

engines (Wärtsilä 16V 46C-CR) of 16.8 MW each at 500 rpm

operating on the 4-stroke cycle, and two gas turbines (GE

http://en.wikipedia.org/wiki/Power_station

http://en.wikipedia.org/wiki/Engine_room

http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C

http://en.wikipedia.org/wiki/Marine_diesel_engine#LNG_Engines

http://en.wikipedia.org/wiki/RMS_Queen_Mary

http://en.wikipedia.org/wiki/Royal_Mail_Ship

http://en.wikipedia.org/wiki/Water-tube_boiler#Yarrow

http://en.wikipedia.org/wiki/C._A._Parsons_and_Company

http://www.wartsila.com/en/engines/medium-speed-engines/wartsila46

http://en.wikipedia.org/wiki/General_Electric_LM2500

100

LM2500+) of 25 MW each, with the power turbine spinning at

3600 rpm, and specific fuel consumption csp=159 g/kWh and

38% thermal efficiency. It uses electrical generators and

electrical motors for propulsion (the first passenger ship with

integrated electric propulsion), with four screw-propellers pods

of 6 m in diameter spinning at 144 rpm (the forward pair fixed

and the aft two rotable 360º in azimuth, removing the need for

a rudder), each of 21.5 MW (Rolls-Royce/Alstom Mermaid),

with five blades separately bolted (the ship carries eight spare

blades). The gas turbines are not housed at or near the

engine room, deep in her hull, but instead are in a

soundproofed enclosure directly beneath the funnel, to

shorten their large air intakes. Service speed is 15 m/s.

A diesel ship's propulsion plant is similar to a ground diesel

plant (as used in cogeneration and emergency power-supply),

with a wide shaft-power range: from 10 kW to 100 MW. They

burn marine diesel oil (MDO), or heavy fuel oil (HFO) when

sulfur emissions can be tolerated (its price is nearly half of the

former). The largest the ship, the lower the engine regime; e.g.

the largest reciprocating engine can deliver 7 MW per cylinder,

which has a bore of D=1 m, stroke of L=4 m, runs at 60 rpm (1

Hz), in the two-stroke cycle, with uni-flow-scavenging, and an

efficiency of η=54% (BSFC=155 g/kWh). Slow engines spin at

<200 rpm, medium-speed engines at 200..1000 rpm, and fast

marine engines at >1000 rpm (in four-stroke cycle, with about

100 kW per cylinder).

When the ship's cargo is a fuel (oil tankers, liquefied natural-

gas carriers, LNG, or liquefied petroleum-gases carriers,

GLP), it could be used to propel the ship, but it is rarely done

because of price (heavy fuel oil is much cheaper than any

other fuel). However, LNG carriers used to be propelled by

http://en.wikipedia.org/wiki/General_Electric_LM2500

http://en.wikipedia.org/wiki/Integrated_electric_propulsion

http://en.wikipedia.org/wiki/Two-stroke_engine

http://en.wikipedia.org/wiki/Four-stroke_engine

http://en.wikipedia.org/wiki/LNG_carrier

101

water turbines to be able to burn, besides the heavy fuel, the

0.1% by mass of the load per day, due to boil-off of the

cryogenic LNG, being uneconomical to re-liquefy the boil-off.

Typical LNG engine power is about 25..30 MW, for sailing at

10 m/s, burning about 50/50 by mass of heavy-fuel and

natural-gas on the loaded trip, and about 80/20 on the ballast

trip (some LNG must be left even when on ballast, to preserve

cryogenic temperatures). Modern LNG carriers use a dual-fuel

diesel engine (burning marine diesel or natural gas in a four-

stroke engine), and electrically-driven propellers; engine

efficiency (about 40 % for diesel against 30 % for the steam

turbine) makes it more economical.

a) LNG motorised by a 32 MW steam turbines. b) Sketch of a 40 MW LNG dual-fuel

electric propulsion system (ABB).

Types of thrusters

A brief grouping may be (in chronological order of

development):

• Paddles, including oars and waterwheels (and swimming).

• Sail, or better sail-keel interaction, because without

hydrodynamic lift, aerodynamic lift in sails could never

produce ship advance against wind. Sailing upwind requires a

http://en.wikipedia.org/wiki/File:Methanier_aspher_LNGRIVERS.jpg

http://www.abb.com/cawp/seitp202/cf12946264c2de39c12575bc002a5ef4.aspx

http://en.wikipedia.org/wiki/Paddle

http://en.wikipedia.org/wiki/Forces_on_sails

http://en.wikipedia.org/wiki/Keel

102

coordination of air forces on the sail with water forces on the

keel and rudder, and tacking (i.e. following a zigzag course).

• Screw propellers, by far the most used, either in bronze,

stainless steel, or fibre-reinforced polymers for small duties.

Different types are:

o Fixed pitch propeller.

o Variable pitch propeller.

o Ducted propeller.

O Azimuth propeller.

• Water jets, used in some fast ships, either powered by gas

turbines or by diesel engines.

The traditional link between the ship's main engine and the

propeller has been a mechanical shaft, supported and kept

aligned by the spring bearings, the stern tube bearings, and

the strut bearing (Fig. 4). Thrust is transmitted to the ship at

the axial thrust bearings.

Sketch of mechanical transmission in ship propulsion.

Most naval propellers are of the screw type, with 3-, 4-, or 5-

blades in the largest vessels (4 is most common), and

advancing speeds of 10..20 m/s (i.e. 20..40 kn (the knot is still

http://en.wikipedia.org/wiki/Tacking_(sailing)

http://webserver.dmt.upm.es/~isidoro/bk3/c17/Propellers.pdf

http://en.wikipedia.org/wiki/Pump-jet

http://www.propellerpages.com/?c=articles&f=2006-02-17_Ship_Propulsion

http://en.wikipedia.org/wiki/Knot_(unit)

103

in widespread use), with the record is at 50 m/s. Enclosing the

propeller in a small duct (nozzle) increases the efficiency.

Notice that ship propellers sit at the rear, whereas in aircraft

they are at the front; the reason lies in the different advancing

low speeds. The rudder is behind the propellers to be effective

at low advance speeds and allow harbour manoeuvres

(although large ships may have separate perpendicular

thrusters). Notice that the rudder is the primary steering

means in ships, whereas fixed-wing aircraft have the rudder

primarily to counter adverse yaw, and turning is basically

achieved by ailerons on the far trailing-edge of each wing.

Water jet propulsion (with ducted axial fans, or with centrifugal

pumps, powered by diesel engines or gas turbines) is used in

some fast and quick-manoeuvrable ships, attaining >20 m/s.

Notice the great difference with aircraft speeds (100..250 m/s);

however, the propulsion power needed is similar, because of

the fluid-density difference in both mediums. Water propellers

are less efficient than air propellers; e.g. ship propellers may

have ηp=0.5..0.7 (against ηp=0.8 for air propellers), with the

smaller value for large tankers (which have advance ratios

J=0.2..0.4; see Propellers, aside).

Manoeuvring is greatly increased by using azimuth thruster,

i.e. a propellers placed in a pod that can be rotated to any

horizontal angle (azimuth), making a rudder unnecessary.

Most azimuth thrusters (often named azipods) are electric.

Astern propulsion is when a ship's propelling mechanism is

developing thrust in a retrograde direction, either to decelerate

and stop, or to go backwards. The usual way is by reversing

pitch in a variable-pitch propeller, but other solutions exist

http://webserver.dmt.upm.es/~isidoro/bk3/c17/Propellers.pdf

http://en.wikipedia.org/wiki/Azimuth_thruster

http://en.wikipedia.org/wiki/Azimuth_thruster

http://en.wikipedia.org/wiki/Azipod

http://www.rolls-royce.com/marine/products/propulsors/podded/

http://en.wikipedia.org/wiki/Astern_propulsion

104

(e.g. Fig. 1f). In aircraft propulsion it is named reverse thrust,

and in land propulsion it is named reverse gear.

The amphibious ship and helicopter carrier Juan Carlos I, the

largest naval unit ever built in Spain (26 000 t displacement,

231 m length), is powered by two diesel generators and one

gas turbine generator, driving two screw pods of 11 MW each.

The F-100 frigates (5800 t, 147 m) have two diesel generators

of 4.5 MW each for normal navigation at 9 m/s, plus two gas

turbines (GE LM-2500) of 17 MW each for advancing at 15

m/s, feeding two screw propellers.

Hydrofoils are watercraft equipped with underwater wings

(hydrofoil surfaces bellow the hull, similar to aerofoils) that

may support the vessel weight at high speed (recall that a

wing lift is almost proportional to the speed squared).The hull

is raised up and out of the water, with great reduction in drag,

and fuel consumption. Unfortunately, impact of the fast and

sharp hydrofoil surfaces, with large marine animals or floating

objects, may cause severe damage (to both). A hydroplane is

a fast motorboat, where the hull shape is such that at high

speed, the weight of the boat is supported by planing forces,

rather than simple buoyancy. There are also small electric

boats; in 2012 the PlanetSolar boat became the first ever solar

electric vehicle to circumnavigate the globe. Electrical

propulsion usually refers to the combination of a internal

combustion engine (ICE: diesel or gas turbine) and electric

motors directly driving the thruster (screw propeller or water

jet), either through a mechanical transmission (with clutch and

gears), or by an electrical generator coupled to the ICE and

electrical transmission.

http://webserver.dmt.upm.es/~isidoro/bk3/c17/Aircraft%20propulsion.pdf

http://en.wikipedia.org/wiki/Reverse_thrust

http://en.wikipedia.org/wiki/Reverse_thrust

http://www.armada.mde.es/ArmadaPortal/page/Portal/ArmadaEspannola/buques_superficie/prefLang_en/04_Fragatas-F100-F80

http://en.wikipedia.org/wiki/Hydrofoil#Hydrofoil_as_foil_supported_craft

http://en.wikipedia.org/wiki/Airfoil

http://en.wikipedia.org/wiki/Hydroplane_(boat)

http://en.wikipedia.org/wiki/Electric_boat

http://en.wikipedia.org/wiki/Electric_boat

http://en.wikipedia.org/wiki/T%C3%BBranor_PlanetSolar



105

There are some crafts that take advantage of aerodynamic

and/or hydrodynamic ground effects to support the weight of

the vehicle (they must rely on buoyancy, however, when

stopped).

There are also small watercrafts for personal use (e.g. water

scooters), some for travel at the surface, and some for

underwater use (see a diver scooter in Fig. 1i).

10.5.2 Matching Engines and Watercrafts

Two kinds of matching may be considered:

• Propulsive matching, i.e. what kind and size of engines are

needed to provide the propulsion power (or thrust) to

compensate the vessel drag at cruise, and the extra power

for acceleration and deceleration. Further engine power

must be accounted for non-propulsive duties, what may be

up to a half in large cruisers.

• Location matching and ancillary interfacing, i.e., engine

rooms, fuel tanks, funnels, etc.

Ships actually move at the same time through two fluids, water

and air, with widely different density, each contributing a

resistance to advance which, to a first approximation, is

proportional to density, so that air-resistance is often

neglected against water resistance. Hence, we are only

considering here skin friction in the submerged part of the hull,

and wave resistance, neglecting the effects of appendages

(propellers, rudders, and bilge keels), pressure drag, and air-

drag (on the superstructure and the part emerged from the

hull).

http://en.wikipedia.org/wiki/Ground_effect_vehicle

http://en.wikipedia.org/wiki/Water_scooter

http://en.wikipedia.org/wiki/Water_scooter

http://en.wikipedia.org/wiki/Underwater_scooter

106

Ship resistance to advance depends a lot on speed, size,

wetted area, and other geometrical parameters, with a typical

share of about 60 % viscous drag (30 % skin drag, 25 % stem-

wake drag, and 5 % air drag), and 40 % wave-making drag;

however, wave drag may rise to 60 % on fast ships and

sailboats, and be under 20 % in very-large ships.

The most important non-dimensional parameters in drag

resistance are: Reynolds number (ReL=v0L/ν), Froude

number ( Fr = v0 Lg ), and the drag coefficient (cD). For

similar geometries, cD=f(Re,Fr) alone, and Froude proposed

that cD,skin=f(Re) and cD,wave=f(Fr).

10.5.3 Wave resistance

Wave-making resistance takes place on surface watercraft

(and to some extent on submarines navigating close to the

surface), and is most important in fast ships and sailboats, i.e.

for Fr~1 (say Fr>0.3). A ship moving over the surface of

undisturbed water sets up waves emanating mainly from the

bow and stern of the ship. The wave pattern consists of

divergent (or diagonal) and transverse (or longitudinal) waves

(Fig. 5), and energy is spent in its formation (which must be

supplied by the propulsion system). These waves were first

studied by Kelvin (in 1887, as a single pressure point traveling

in a straight line over the water surface), who found that

regardless of the speed of the ship, they were always

contained in the 19.5º semi-angle.

http://en.wikipedia.org/wiki/Reynolds_number

http://en.wikipedia.org/wiki/Froude_number

http://en.wikipedia.org/wiki/Froude_number

http://en.wikipedia.org/wiki/Drag_coefficient

107

Ship wave pattern of transversal and divergent waves on the water surface

Total ship drag is the sum of skin friction (viscous resistance,

which monotonically increases with speed), and wave

resistance, which shows up-and-downs in its dependence with

ship speed, due to interference effects of the bow pattern with

the stern pattern (the wavelength of both transverse and

divergent waves grows with speed squared).

Increasing speed is almost always appealing in all kind of

vehicles: you arrive sooner and may do more things there,

your freight arrives sooner and you may increase your

turnaround, and, for war and emergency, you can reach to the

target and escape from the site sooner. But the power

required to propel a ship through the water is the product of

total hull resistance and ship speed, and there are a v02 term

in the skin-resistance term, and further speed effects on the

skin-drag coefficient, what finally yields a power requirement

proportional to v03 , v0

4 , or v05 . No wonder why typical service

speed in medium and large ships is about 15 m/s.

For high-speed boats, the best is to have the minimum wetted

area but a submerged propeller; different trade-offs are

achieved in SWATH-ships (small waterline area twin hull

http://en.wikipedia.org/wiki/SWATH

108

ships), thin elongated bows (like catamaran), hydrofoil ships,

hovercraft, and hydroplanes. In fact, supercavitation under

water (see Supercavitation, below) can be considered a

means of reducing the wetted area of the moving object.

Large ships may reduce drag by using a bulbous bow (a

protruding bulb below the bow waterline). In a conventionally

shaped bow, a bow wave forms immediately before the bow.

When a bulb is placed below the water ahead of this wave,

water is forced to flow up over the bulb. If the trough formed

by water flowing off the bulb coincides with the bow wave, the

two partially cancel out and reduce the vessel's wake.

10.5.4 Submarines

A typical conventional submarine is about 70 m long, 7 m in

diameter, 2500 t, have a crew of some 30 people, and a 3..4

MW diesel-electric plant (composed of 2 or 3 engines, for

redundancy and load matching); non-propulsion power

requirements may reach 100 kW. The propulsion system, Fig.

6a, which may occupy up to 50 % of the pressurised hull

volume, typically operates in the following way:

• Normal operation is in fully-submerged navigation (patrol

mode), down to 200 m depth limit, with electric lead-acid

batteries supplying propulsion and housekeeping power. The

typical speed is about 2 m/s for a maximum endurance of

about 8..10 hours (0.3 MW), or a maximum speed of 15 m/s

for about half an hour (3 MW).

• Snorkel operation (or snorting), at periscope depth (about 10

m below surface), is primarily used to recharge the batteries

with the diesel engines, since the boat speed is limited to

about 3 m/s by structural strength of the snorkel mast. The

snorkel is a device which allows a submarine to operate

submerged, taking in air from above the surface (engine

http://en.wikipedia.org/wiki/Wave-piercing

http://en.wikipedia.org/wiki/Bulbous_bow

109

exhaustion takes place always under water, to minimise the

thermal signature; in military surface ships the exhaust is

through a funnel, but with the flue gases diluted with air to

minimise thermal signature). A key feature is the head-valve

on top of the air-intake mast that must prevent water from

entering.

• Surface navigation, diesel powered, with electric generators

delivering a total of 3..4 MW to one or two low-rpm DC-

motors directly driving the propeller (one, or two counter-

rotating), providing a speed of up to 5..6 m/s, with endurance

limited to one or two months by fuel-tank capacity.

Propulsion power is proportional to v3, but endurance is

proportional to exp(−bv), with b≈0.35 s/m. Hidden

submerged endurance is limited by batteries energy capacity

to less than 12 h; even with an air-independent engine (see

AIP, below) it is limited by LOX mass to less than 15 days

(for a large 50 t LOX load); on nuclear-powered submarines

it is the crew endurance that sets a limit to over 3 months.

Waste disposal may endanger stealth, particularly those

mitted by the propulsion system: exhaust gases, thermal

plume, ballast, noise... Submarine propellers are relatively

large and have many blades (Fig. 1h) with a complex

curvature, intended to minimize noise while in patrol

navigation, and cavitation at high spinning rate.

Nuclear submarines are much more powerful and truly

'submarine operational' (i.e. able to travel underwater, down

to 500 m depth, at high speed for unlimited periods), though

they have a big handicap: in peace-time they are banned to

operate in most-interesting litoral regions. Their nuclear

reactors provide 100..200 MW of heat that convert to 30..70

MW of power in a steam-turbine engine. There are almost

110

400 nuclear submarines worldwide (up to 10 being replaced

each year), the largest being the Russian Typhon class (175

m long, 48 000 t submerged displacement, 75 MW power),

and the smaller being the French Rubis class (74 m long, 2

600 t submerged displacement, 7 MW power).

Submarines have two hulls: the outer hull provides a

streamlined shape to minimise resistance, whereas the inner

hull allows normal habitable pressure (around 100 kPa) by

protecting the interiors from extreme pressures at greater

ocean depths; the hulls are generally made from an alloy

which is a combination of nickel, molybdenum, and

chromium. Between these two hulls are located the ballast

tanks (Fig. 6b), which serve to change buoyancy between

surface and submerged conditions; changes in navigation

depth and attitude are dynamically performed with the

propulsion and the control planes; there are other

interconnected internal tanks, independent of ballast tanks,

to fine-control attitude and buoyancy. In case of a submarine

is unable to surface, there is a life-support system with a few

days of autonomy, and rescue vehicles (Fig. 6c) that, once

transported to a close location, can travel independently to

the downed submarine, latch onto the submarine over a

hatch, create an airtight seal so that the hatch can be

opened, and load up the crew. A diving bell may be lowered

from a support ship down to the submarine, where a similar

operation occurs. To raise the submarine, typically after the

crew has been extracted, pontoons may be placed around

the submarine and inflated to float it to the surface.

111

a) Sketch of the standard diesel-electric submarine propulsion. b) Cross-section

diagram showing the two hulls (pressurised and hydrodynamic) and the ballast

system. c) Submarine rescue vehicle.

http://submarinewarriors.com/facts/

http://www.maritime.org/tech/descon.htm

http://en.wikipedia.org/wiki/Ballast_tank

http://en.wikipedia.org/wiki/Ballast_tank

http://submarinewarriors.com/facts/

112

PERTEMUAN 11 Avionics, Navigation, and Instrumention

11.1 Pendahuluan


a. Avionics System Patterned After Apollo; Features and

Capabilities Unlike Any Other in the Industry

b. Central Processor Units Were Available Off the Shelf—

Remaining Hardware and Software Would



memahami Avionics System Patterned After Apollo; Features and

Capabilities Unlike Any Other in the Industry Central Processor

Units Were Available Off the Shelf— Remaining Hardware and

Software Would



menjelaskan Avionics System Patterned After Apollo; Features and

Capabilities Unlike Any Other in the Industry Central Processor Units

Were Available Off the Shelf— Remaining Hardware and Software

Would



penilaian





113

11.5 Ringkasan Materi:

11.5.1 Avionics System Patterned After Apollo; Features and

Capabilities Unlike Any Other in the Industry

The preceding tenets were very much influenced by NASA‘s

experience with the successful Apollo primary navigation,

guidance, and control system. The Apollo-type guidance

computer, with additional specialized input/output hardware,

an inertial reference unit, a digital autopilot, fly-by-wire thruster

control, and an alphanumeric keyboard/display unit

represented a nonredundant subset of critical functions for

shuttle avionics to perform. The proposed shuttle avionics

represented a challenge for two principal reasons: an

extensive redundancy scheme and a reliance on new

technologies.

Shuttle avionics required the development of an overarching

and extensive redundancy management scheme for the entire

integrated avionics system, which met the shuttle requirement

that the avionics system be ―fail operational/fail safe‖—i.e.,

two-fault tolerant with reaction times capable of maintaining

safe computerized flight control in a vehicle traveling at more

than 10 times the speed of high-performance military aircraft.

Shuttle avionics would also rely on new technologies—i.e.,

time-domain data buses, digital fly-by-wire flight control, digital

autopilots for aircraft, and a sophisticated software operating

system that had very limited application in the aerospace

industry of that time, even for noncritical applications, much

less for ―man-rated‖ usage. Simply put, no textbooks were

available to guide the design, development, and flight

certification of those technologies and only a modicum of off-

the-shelf equipment was directly applicable.

114

Why Fail Operational/Fail Safe?

Previous crewed spacecraft were designed to be fail safe,

meaning that after the first failure of a critical component, the

crew would abort the mission by manually disabling the

primary system and switching over to a backup system that

had only the minimum capability to return the vehicle safely

home. Since the shuttle‘s basic mission was to take humans

and payloads safely to and from orbit, the fail-operational

requirement was intended to ensure a high probability of

mission success by avoiding costly, early termination of

missions.

Early conceptual studies of a shuttle-type vehicle indicated

that vehicle atmospheric flight control required full-time

computerized stability augmentation. Studies also indicated

that in some atmospheric flight regimes, the time required for

a manual switchover could result in loss of vehicle. Thus, fail

operational actually meant that the avionics had to be capable

of ―graceful degradation‖ such that the first failure of a critical

component did not compromise the avionic system‘s capability

to maintain vehicle stability in any flight regime.

The graceful degradation requirement (derived from the fail-

operational/ fail-safe requirement) immediately provided an

answer to how many redundant computers would be

necessary. Since the computers were the only certain way to

ensure timely graceful degradation—i.e., automatic detection

and isolation of an errant computer—some type of

computerized majority-vote technique involving a minimum of

three computers would be required to retain operational status

and continue the mission after one computer failure. Thus,

four computers were required to meet the fail-operational/fail-

safe requirement. That level of redundancy applied only to the

115

computers. Triple redundancy was deemed sufficient for other

components to satisfy the fail-operational/fail-safe

requirement.

11.5.2 Central Processor Units Were Available Off the Shelf—

Remaining Hardware and Software Would Need to be

Developed

The next steps included: selecting computer hardware that

was for military use yet commercially available; choosing the

actual configuration, or architecture, of the computer(s), data

bus network, and bus terminal units; and then developing the

unique hardware and software to implement the world‘s first

two-fault-tolerant avionics.

In 1973, only two off-the-shelf computers available for military

aircraft offered the computational capability for the shuttle.

Both computers were basic processor units—termed ―central

processor units‖—with only minimal input/output functionality.

NASA selected a vendor to provide the central processor units

plus new companion input/output processors that would be

developed to specifications provided by architecture

designers. At the time, no proven best practices existed for

interconnecting multiple computers, data buses, and bus

terminal units beyond the basic active/standby manual

switchover schemes.

The architectural concept figured heavily in the design

requirements for the input/output processor and two other new

types of hardware ―boxes‖ as

116

well as the operating system software, all four of which had to

be uniquely developed for the shuttle digital data processing

subsystem. Each of those four development activities would

eventually result in products that established new limits for the

so-called ―state of the art‖ in both hardware and software for

aerospace applications.

In addition to the input/output processor, the other two new

devices were the data bus transmitter/receiver units—referred

to as the multiplex interface adapter—and the bus terminal

units, which was termed the ―multiplexer/demultiplexer.‖ NASA

designated the software as

the Flight Computer Operating System. The input/output

processors (one paired with each central processor unit) was

necessary to interface the units to the data bus network. The

numerous multiplexer/demultiplexers would serve as the

remote terminal units along the data buses to effectively

interface all the various vehicle subsystems to the data bus

117

network. Each central processor unit/input/output processor

pair was called a general purpose computer.

The multiplexer/demultiplexer was an extraordinarily complex

device that provided electronic interfaces for the myriad types

of sensors and effectors associated with every system on the

vehicle. The multiplex interface adaptors were placed internal

to the input/output processors and the

multiplexer/demultiplexers to provide actual electrical

connectivity to the data buses. Multiplex interface adaptors

were supplied to each manufacturer of all other specialized

devices that interfaced with the serial data buses. The protocol

for communication on those buses was also uniquely defined

The central processor units later became a unique design for

two reasons: within the first several months in the field, their

reliability was so poor that they could not be certified for the

shuttle ―man-rated‖ application; and following the Approach

and Landing Tests (1977), NASA found that the software for

orbital missions exceeded the original memory capacity. The

central processor units were all upgraded with a newer

memory design that doubled the amount of memory. That

memory flew on Space Transportation System (STS)-1 in

1981.

Although the computers were the only devices that had to be

quad redundant, NASA gave some early thought to simply

creating four identical strings with very limited

interconnections. The space agency quickly realized,

however, that the weight and volume associated with so much

additional hardware would be unacceptable. Each computer

needed the capability to access every data bus so the system

could reconfigure and regain capability after certain failures.

NASA accomplished such reconfiguration by software

118

reassignment of data buses to different general purpose

computers.

The ability to reconfigure the system and regain lost capability

was a novel approach to redundancy management.

Examination of a typical mission profile illustrates why NASA

placed a premium on providing reconfiguration capability.

Ascent and re-entry into Earth‘s atmosphere represented the

mission phases that required automatic failure detection and

isolation capabilities, while the majority of on-orbit operations

did not require full redundancy when there was time to

thoroughly assess the implications of any failures that

occurred prior to re-entry. When a computer and a critical

sensor on another string failed, the failed computer string

could be reassigned via software control to a healthy

computer, thereby providing a fully functional operational

configuration for re-entry.

The Costs and Risks of Reconfigurable Redundancy

The benefits of interconnection flexibility came with costs, the

most obvious being increased verification testing needed to

certify each configuration performed as designed. Those

activities resulted in a set of formally certified system

reconfigurations that could be invoked at specified times

during a mission. Other less-obvious costs stemmed from the

need to eliminate single-point failures. Interconnections

offered the potential for failures that began in one redundant

element and propagated throughout the entire redundant

system—termed a ―single-point failure‖—with catastrophic

consequences. Knowing such, system designers placed

considerable emphasis on identification and elimination of

failure modes with the potential to become single-point

failures. Before describing how NASA dealt with potential

119

catastrophic failures, it is necessary to first describe how the

redundant digital data processing subsystem was designed to

function.

Establishing Synchronicity

The fundamental premise for the redundant digital data

processing subsystem operation was that all four general

purpose computers were executing identical software in a

time-synchronized fashion such that all received the exact

same data, executed the same computations, got the same

results, and then sent the exact same time-synchronized

commands and/or data to other subsystems.

Maintenance of synchronicity between general purpose

computers was one of the truly unique features of the newly

developed Flight Computer Operating System. All four general

purpose computers ran in a synchronized fashion that was

keyed to the timing of the intervals when general purpose

computers were to query the bus terminal units for data, then

process that data to select the best data from redundant

sensors, create commands, displays, etc., and finally output

those command and status data to designated bus terminal

units.

120

NASA designed the four general purpose computer redundant

set to gracefully degrade from either four to three or from three

to two members. Engineers tailored specific redundancy

management algorithms for dealing with failures in other

redundant subsystems based on knowledge of each

subsystem‘s predominant failure modes and the overall effect

on vehicle performance.

NASA paid considerable attention to means of detecting

subtle latent failure modes that might create the potential for a

simultaneous scenario. Engineers scrutinized sensors such as

gyros and accelerometers in particular for null failures. During

orbital operation, the vehicle typically spent the majority of

time in a quiescent flight control profile such that those

sensors were operating very near their null points. Prior to re-

entry, the vehicle executed some designed maneuvers to

purposefully exercise those devices in a manner to ensure the

absence of permanent null failures. The respective design

teams for the various subsystems were always challenged to

strike a balance between early detection of failures vs.

121

nuisance false alarms, which could cause the unnecessary

loss of good devices.

Decreasing Probability of Pseudo-simultaneous Failures

There was one caveat regarding the capability to be two-fault

tolerant— the system was incapable of coping with

simultaneous failures since such failures obviously defeat the

majority-voting scheme. A nuance associated with the

practical meaning of ―simultaneous‖ warranted significant

attention from the designers. It was quite possible for internal

circuitry in complex electronics units to fail in a manner that

wasn‘t immediately apparent because the circuitry wasn‘t used

In all operations. This failure could remain dormant for

seconds, minutes, or even longer before normal activities

created conditions requiring use of the failed devices;

however, should another unrelated failure occur that created

the need for use of the previously failed circuitry, the practical

effect was equivalent to two simultaneous failures.

To decrease the probability of such pseudo-simultaneous

failures, the general purpose computers and

multiplexer/demultiplexers were designed to constantly

execute cyclic background self-test operations and

Ferreting Out Potential Single-point Failures

Engineering teams conducted design audits using a technique

known as failure modes effects analysis to identify types of

failures with the potential to propagate beyond the bounds of

the fault-containment region in which they originated. These

studies led to the conclusion that the digital data processing

subsystem was susceptible to two types of hardware failures

with the potential to create a catastrophic condition, termed a

―nonuniversal input/output error.‖ As the name implies, under

such conditions a majority of general purpose computers may

122

not have received the same data and the redundant set may

have diverged into a two-on-two configuration or simply

collapsed into four disparate members.

Engineers designed and tested the topology, components,

and data encoding of the data bus network to ensure that

robust signal levels and data integrity existed throughout the

network. Extensive laboratory testing confirmed, however, that

the two types of failures would likely create conditions

resulting in eventual loss of all four computers.

The first type of failure and the easiest to mitigate was some

type of physical failure causing either an open or a short circuit

in a data bus. Such a condition would create an impedance

mismatch along the bus and produce classic transmission line

effects; e.g., signal reflections and standing waves with the

end result being unpredictable signal levels at the receivers of

any given general purpose computer. The probability of such a

failure was deemed to be extremely remote given the robust

mechanical and electrical design as well as detailed testing of

the hardware, before and after installation on the Orbiter.

The second type of problem was not so easily discounted.

That problem could occur if one of the bus terminal units

failed, thus generating unrequested output transmissions.

Such transmissions, while originating from only one node in

the network, would nevertheless propagate to each general

purpose computer and disrupt the normal data bus signal

levels and timing as seen by each general purpose computer.

It should be mentioned that no amount of analysis or testing

could eliminate the possibility of a latent, generic software

error that could conceivably cause all four computers to fail.

Thus, the program deemed that a backup computer, with

software designed and developed by an independent

123

organization, was warranted as a safeguard against that

possibility.

This backup computer was an identical general purpose

computer designed to ―listen‖ to the flight data being collected

by the primary system and make independent calculations that

were available for crew monitoring. Only the on-board crew

had the switches, which transferred control of all data buses to

that computer, thereby preventing any ―rogue‖ primary

computers from ―interfering‖ with the backup computer.

Its presence notwithstanding, the backup computer was never

considered a factor in the fail-operational/fail-safe analyses of

the primary avionics system, and—at the time of this

publication—had never been used in that capacity during a

mission.

124

PERTEMUAN 12

Jet Fighter Aircraft

12. 1 Pendahuluan


a. Jet Fighter Aircraft

b. A Brief History of the Development of Jet Fighter Aircraft

12. 2 Tujuan Instruksional Umum


memahami Jet Fighter Aircraft dan A Brief History of the

Development of Jet Fighter Aircraft

12. 3 Tujuan Instruksional Khusus


menjelaskan Jet Fighter Aircraft dan A Brief History of the

Development of Jet Fighter Aircraft

12. 4 Skenario Pembelajaran


penilaian





12. 5 Ringkasan Materi:

12.5.1 Jet fighter aircraft

USE of the term ‗aircraft generations‘ first appeared in the

early 1990s and its concept applies to jet fighter aircraft

exclusively.1,2 Although use ofthis terminology remains

unofficial and imprecise, it is generally accepted that Dr.

Richard Hallion was one of the first to coin use of the term

125

when describing the leap-frogging improvements in jet fighter

design and development.

RAF Panavia Tornado GR4, a RAF Eurofighter Typhoon FGR4 and an

Indian Air Force Sukhoi Su30 MKI

In this context, ‗generations‘ denotes the ‗features‘ of jet

fighter aircraft. Some writers have described these

generations slightly differently over time 3,4 including Hallion

himself2 and this has generally led to confusion in how jet

fighter aircraft generations should be categorized. One writer

even questions the origin and timing of the use of the terms

fighter ‗generations‘, stating the first use of this terminology

actually originated in Russia during the mid-1990s, when

Russian officials there used the term during planning stages of

a Russian equivalent to the US Joint Strike Fighter.

While the terminology and categorization may remain

imprecise, the use of the term ‗generations‘ was born out of

necessity, due to a need to describe the continuous

improvements in the operational performance and features of

jet fighter aircraft, which have occurred via major advances in

airframe and engine design, avionics and weapons systems.

It should be remembered that jet fighter aircraft improvements

have not only come about as the result of upgrades and

retrospective fit-outs to existing airframes, but have also

occurred as a result of the

126

complete re-design of new airframes (made necessary when

technological innovations cannot be incorporated into existing

airframes any longer). This is known as a ‗generational shift‘.

Legacy flight including an A-10 thunderbolt II, F-4 Phantom, F-86 Sabre and P-38

Lightning, flying in formation. Photographed at Aviation Nation 2009, Nellis Air

Force Base, Las Vegas, Nevada, USA

Such major generational shifts in jet fighter aircraft design

have progressively occurred over the last 60 years, beginning

towards the end of World War II and extending into the mid

1950s – this period becoming known as the age of the ‗First

Generation‘ of jet fighters.

This article focuses on the quantum improvements in jet

fighter aircraft, commencing from the first generation to the

current, fifth generation of aircraft and beyond. It attempts to

provide a evolutionary overview of jet fighter aircraft spanning

five generations, based on their features. It also discusses

contemporary issues regarding the future of jet fighter aircraft

development, particularly considering the high costs

associated with this endeavour, the current forced reductions

in military spending due to the recent global financial crisis,

and the increasing use of more economical and durable

unmanned aerial vehicles (UAVs).

127

12.5.2 A Brief History of the Development of Jet Fighter Aircraft

Although high-powered propeller-driven aircraft dominated the

skies in every theatre of conflict during World War II, it was

Nazi Germany whom began early work on turbine-powered

(jet) aircraft design and development. The Allies, and

separately the Russians, by late WWII, had their own jet

fighter ‗R&D‘ programs well in place.

In Nazi Germany‘s case, this had reached such an advanced

state that the Luftwaffe had by Nov. 1943, a number of jet

fighters (Me 262 Sparrow, Me 263B Komet, and in 1945,

Heinkel He 162) and jet bombers (Arado Ar 234), in its military

arsenal.

Fortunately for the Allies, Hitler saw the Me 262 as a ‗blitz

bomber‘ rather than as an ‗air superiority‘ fighter, for which it

was originally designed.5

Some Me 262s, and Komet 263s did see limited action against

Allied fighters, and the results, mostly due to their speed and

firepower, were spectacular in favour of the Luftwaffe in nearly

every case, confirming Hitler‘s poor understanding of the new

jet age. However in the case of the Komet 263, its limited

endurance, temperamental powerplant and its landing gear,

posed an even bigger danger to its own pilots.

While the Germans were very innovative with their jet aircraft

designs, they were not the first nation to fly the world‘s first jet

fighter. This honour went to Robert Stanley of the US, who

flew his jet-powered American Bell XP-59A Airacomet at

Muroc, California on Oct 1, 1942 into the history books. The

other contender from Britain, the Gloster Meteor flew only six

months later, on March 5th 1943. It is important to recognise

this fact, as the Gloster Meteor (but not the Bell Airacomet),

128

was a fully equipped and capable, operational fighter aircraft

when it made its first respective flight, unlike the Me 262,

which was not.

The Bell Airacomet did see limited familiarization experience,

but its performance was deemed unsatisfactory and it was

quickly withdrawn from service. In the literature, one often

finds that the Me 262 is cited as the ‗world‘s first operational

jet fighter‘, in fact this is incorrect, as the original prototype of

the Me 262 made its first flight on April 18th 1941, using a

piston engine.

The Me262 did not fly as a jet-powered aircraft until the third

version of the plane (Me 262v3) flew on July 18th 1942,

though that flight was made without the full kit of military

equipment, and was made with a tail wheel.5 Only in its sixth

version of the series (Me262v6) did the Me 262 jet fly with all

its intended military gear and tricycle undercarriage, which

occurred on Oct. 17th 1942.

History records that the Me262, being sleek, fast and

powerful, with its swept-back wings and shark-like

appearance, was far in advance of any other aircraft of its

time. Due to its speed, it could easily evade defending Allied

fighter aircraft while attacking Allied bombers with its lethal

cannon fire. Despite its short yet brilliant wartime career, the

Me262 had changed aerial warfare permanently and it had

also heavily influenced jet fighter aircraft designs for years to

come.

Interestingly after WWII, both the Allies and the Soviets

extensively studied captured Me 262s, which aided the design

and development of their own early jet fighter aircraft. In the

129

case of the former, the design of the Me262s airofoil and slats

were incorporated into the American F-86 Sabre design.

Furthermore, when compared to earlier versions of the Gloster

Meteor, the Me262 was faster and had a more superior gun

platform. It also provided better cockpit visibility, particularly at

the sides and to the rear.

12.5.3 First Generation Jet Fighters

Commencing from mid 1940s (mostly towards the end of

WWII) and extending through to the mid 1950s (including the

1950-1953 Korean War), was the period of most research,

design and development that contributed towards first

generation fighter designs. It should also be remembered that

the period between 1945 and extending into the 1960s were

also the early years of the Cold War.

One of the main distinctions of the First generation of fighter

aircraft was that they operated at subsonic speeds in level

flight and that their jet engines were not equipped with

afterburners. These aircraft had rudimentary avionics systems

and essentially no radar or self-protection countermeasures

for engaging adversaries.

Another characteristic of First generation aircraft was that their

armament systems were also very rudimentary, as they used

a combination of machine guns and/or cannons (similarly to

piston-engined fighter aircraft of the time) and ordnance such

as largely unguided bombs and rockets. Examples of jet

fighter aircraft within this generation from the West include the

North American F-86 Sabre and later the F-100C Super

Sabre, the Grumann F9F-2B Panther, the Republic F-84

Thunderjet.

130

From the Soviets came the Mikoyan-Gureyich Mig-15 (NATO

codename Midget) and Mig17 Fresco. When the F-86 Sabre

and Mig-15 jets encountered each other during the Korean

War, this was the first time in history that jet fighter aircraft had

engaged each other in aerial combat.

12.5.4 Second Generation Jet Fighters

This covers the period from circa mid-1950s to the early

1960s. One of the main distinctions of the Second generation

of fighter aircraft was that these aircraft operated at

supersonic speeds in level flight, thanks being largely due to

advances in aerodynamics and engine design of this time.

In this period, radar warning receivers were introduced, as

well as air-to-air radar. Armament systems improved

tremendously with the introduction of both infrared and semi-

active guided missiles, and while air-to-air combat was still

undertaken mostly visually, extended engagement ranges of

radar-guided missiles began.

During this period there were two conflicts in various parts of

Asia, the first of which was the ‗Malayan Emergency‘ which

commenced in 1948 and ended in 1960.6 The second was the

first Indochina War between the French colonial forces against

the Vietnamese ‗Viet Minh‘ forces, who defeated the French.

Once the French left Vietnam, the vacuum was quickly

replaced by larger US forces (this was known as the second

IndoChina War) later better known as the Vietnam War,

lasting some 13 years.7

Although there was no air-to-air combat in the Malayan conflict

as the communist forces did not have any aircraft of their own,

allowing the RAAF to dominate the skies, the Vietnam conflict

131

was as famous for the air-to-air combat that occurred over

Vietnamese skies, as it was for the hostilities occurring on the

ground.

The third conflict, the Indo-Pakistani War of 19658, was

initially a ground war that quickly escalated into a large scale

aerial war. It saw much air-to-air combat between Indian Air

Force jets such as Vampire FB Mk 52s, Dassault Mystere IVs,

Hawker Hunters, as well as Folland Gnat jet fighters pitted

against the Pakistani Air Force‘s mainly F-86 Sabres and F-

104 Starfighters.

Examples of jet fighter aircraft within this generation include,

from the West, Hawker T7 Hunter, the Lockheed F-104

Starfighter, the Dassualt IV Mystere, and from the Soviets the

Mikoyan-Gureyich Mig-19 Farmer and Mig-21 Fishbed.

12.5.5 Third Generation Jet Fighter

This covers the period circa 1960 to 1970. Major

advancements made it possible for jet fighter aircraft to carry

out aerial combat engagements that moved beyond visual

range, or in other words, it was no longer necessary to visually

identify enemy jet fighters in order to attack them. This was

due to the enhancement of sophisticated radar systems such

as Doppler radar, which permitted a ‗look-down and shoot-

down capability‘. It was also the time in which functionality of

the ‗multi-role‘ jet fighter first appeared.

This period also saw the introduction of semi-active guided

radio frequency missiles such as the advanced Sparrow AIM-7

and the Apex AA-7, in addition to off-bore sight targeting

systems. Overall, this period saw significant improvements in

weapons systems, avionics, but also in jet fighter aircraft

manoeuvrability due to much sleeker airframe designs.

132

The period 1962 to 1975 saw the world witnessing the horrors

of the Vietnam war, which became a major proving ground for

jet fighter aircraft of the West. Two commonly used examples

flown were the McDonnell-Douglas F4 Phantom and the F-104

Thunderjet, which were pitted against their Eastern Bloc

adversaries, mainly the Mig-21 Fishbed.

Other examples of jet fighter aircraft of this generation include,

from the West, the Sepecat MK1A Jaguar, BAc Harrier,

Northrop F-5 Tiger, the Convair F-106 Delta Dart and the

Dassault Mirage F-I, and from the Soviets the Sukhoi Su-17,

Su-20, Su-Su-25 Frogfoot, and Mig-23 and Mig-25.

133

PERTEMUAN 13 Flotation, hydrostatics, and ship stability

13.1 Pendahuluan


a. Buoyancy and Stability

b. Archimedes principle

c. The gentle art of balloning

d. Stability of floating bodies

13. 2 Tujuan Instruksional Umum


memahami Buoyancy and Stability, Archimedes principle,The

gentle art of balloning, Stability of floating bodies

13. 3 Tujuan Instruksional Khusus


menjelaskan Buoyancy and Stability,Archimedes principle,The

gentle art of balloning, Stability of floating bodies

13. 4 Skenario Pembelajaran


penilaian





13. 5 Ringkasan Materi:

13.5.1 Bouyancy and stability

Fishes, whales, submarines, balloons and airships all owe

their ability to float to buoyancy, the lifting power of water and

air. The understanding of the physics of buoyancy goes back

as far as antiquity and probably sprung from the interest in

134

ships and shipbuilding in classic Greece. The basic principle

is due to Archimedes. His famous Law states that the

buoyancy force on a body is equal and oppositely directed to

the weight of the fluid that the body displaces. Before his

time it was thought that the shape of a body determined

whether it would sink or float.

The shape of a floating body and its mass distribution do,

however, determine whether it will float stably or capsize.

Stability of floating bodies is of vital importance to

shipbuilding

— and to anyone who has ever tried to stand up in a small

rowboat. Newtonian mechanics not only allows us to derive

Archimedes‘ Law for the equilibrium of floating bodies, but

also to characterize the deviations from equilibrium and

calculate the restoring forces. Even if a body floating in or on

water is in hydrostatic equilibrium, it will not be in complete

mechanical balance in every orientation, because the center

of mass of the body and the center of mass of the displaced

water, also called the center of buoyancy, do not in general

coincide.

The mismatch between the centers of mass and buoyancy

for a floating body creates a moment of force, which tends to

rotate the body towards a stable equilibrium. For submerged

bodies, submarines, fishes and balloons, the stable

equilibrium will always have the center of gravity situated

directly below the center of buoyancy. But for bodies floating

stably on the surface, ships, ducks, and dumplings, the

center of gravity is mostly found directly above the center of

buoyancy. It is remarkable that such a configuration can be

stable. The explanation is that when the surface ship is tilted

away from equilibrium, the center of buoyancy moves

instantly to reflect the new volume of displaced water.

135

Provided the center of gravity does not lie too far above the

center of buoyancy, this change in the displaced water

creates a moment of force that counteracts the tilt.

13.5.2 Archimedes priciple

Mechanical equilibrium takes a slightly different form than

global hydrostatic equilibrium (2.18) on page 27 when a body

of another material is immersed in a fluid. If its material is

incompressible, the body retains its shape and displaces an

amount of fluid with exactly the same volume. If the body is

compressible, like a rubber ball, the volume of displaced fluid

will be smaller. The body may even take in fluid, like a

sponge or the piece of bread you dunk into your coffee, but

we shall disregard this possibility in the following

A body which is partially immersed with a piece inside and

another outside the fluid may formally be viewed as a body

that is fully immersed in a fluid with properties that vary from

place to place. This also covers the case where part of the

body is in vacuum which may be thought of as a fluid with

vanishing density and pressure.

Let the actual, perhaps compressed, volume of the immersed

body be V with surface S. In the field of gravity an

unrestrained body with mass density body is subject to two

forces: its weight

z

FG D body g dV;

V

and the buoyancy due to pressure acting on its surface,

I

FB D p dS :

136

In a constant gravitational field, g.x/ D g0, everything

simplifies. The weight of the body and the buoyancy force

become instead,

FG D Mbody g0; FB D Mfluid g0:

Since the total force is the sum of these contributions, one

might say that buoyancy acts as if the displacement were

filled with fluid of negative mass Mfluid. In effect the

buoyancy force acts as a kind of antigravity.

The total force on an unrestrained object is now,

F D FG C FB D .Mbody Mfluid/g0:

If the body mass is smaller than the mass of the displaced

fluid, the total force is directed upwards, and the body will

begin to rise, and conversely if the force is directed

downwards it will sink. Alternatively, if the body is kept in

place, the restraints must deliver a force F to prevent the

object from moving.

In constant gravity, a body can only hover motionlessly inside

a fluid (or on its surface) if its mass equals the mass of the

displaced fluid,

A fish achieves this balance by adjusting the amount of water

it displaces (Mfluid) through contraction and expansion of its

body by means of an internal air-filled bladder. A submarine,

in contrast, adjusts its mass (Mbody) by pumping water in

and out of ballast tanks

137

13.5.3 The gentle art of ballooning

The first balloon flights are credited to the Montgolfier

brothers who on November 21, 1783 flew an untethered

manned hot-air balloon, and to Jacques Charles who on

December 1 that same year flew a manned hydrogen gas

balloon (see fig. 3.1). In the beginning there was an intense

rivalry between the advocates of Montgolfier and Charles

type balloons, respectively called la Montgolfiere` and la

Charliere`, which presented different advantages and

dangers to the courageous fliers. Hot air balloons were

easier to make although prone to catch fire, while hydrogen

balloons had greater lifting power but could suddenly

explode. By 1800 the hydrogen balloon had won the day,

culminating in the huge (and dangerous) hydrogen airships

of the 1930s. Helium balloons are much safer, but also

much more expensive to fill. In the last half of the twentieth

century hot-air balloons again came into vogue, especially

for sports, because of the availability of modern strong

lightweight materials (nylon) and fuel (propane).

Let M denote the mass of the balloon at height z above the

ground. This includes the gondola, the balloon skin, the

payload (passengers), but not the gas (be it hot air,

hydrogen or helium). The mass of the balloon can diminish

if the balloon captain decides to throw out stuff from the

gondola to increase its maximal height, also called the

ceiling, and often sand bags are carried as ballast for this

purpose. The condition (3.7) for the balloon to float stably at

height z above the ground now takes the form,

138

where 0 the density of the gas, is the density of the

displaced air, and V the volume of the gas at height z. On

the right we have left out the tiny buoyancy VM due to the

volume VM of the material of the balloon itself. If the left-

hand side of this equation is smaller or larger than the right-

hand side, the balloon will rise or fall.

Contemporary pictures of the first flights of the Montgolfier hot air

balloon (left) and the Charles hydrogen balloon (right). The first ascents

were witnessed by huge crowds. Benjamin Franklin, scientist and one

of the founding fathers of the US, was present at the first Montgolfier

ascent and was deeply interested in the future possibilities of this

invention, but did not live to see the first American hot air balloon flight

in 1793.

A modern large hydrogen or helium balloon typically begins

its ascent being only partially filled, assuming an inverted

tear-drop shape. During the ascent the gas expands because

of the fall in ambient air pressure, and eventually the balloon

becomes nearly spherical and stops expanding (or bursts)

because the ―skin‖ of the balloon cannot stretch further. To

avoid bursting the balloon can be fitted with a safety valve.

Since the density of the displaced air falls with height, the

balloon will eventually reach a ceiling where it would hover

139

permanently if it did not lose gas. In the end no balloon stays

aloft forever.

13.5.4 Stability of Floating bodies

Although a body may be in buoyant equilibrium, such that

the total force composed of gravity and buoyancy vanishes,

F D FG C FB D 0, it may still not be in complete mechanical

equilibrium. The total moment of all the forces acting on the

body must also vanish; other-wise an unrestrained body will

necessarily start to rotate. In this section we shall discuss

the mechanical stability of floating bodies, whether they

float on the surface, like ships and ducks, or float

completely submerged, like submarines and fish. To find

the stable configurations of a floating body, we shall first

derive a useful corollary to Archimedes‘ Principle

concerning the moment of force due to buoyancy.

Moments of gravity and buoyancy

The total moment is like the total force a sum of two

terms,

with one contribution from gravity,

and the other from pressure, the moment of buoyancy,

If the total force vanishes, F D 0, the total moment will be

independent of the origin of the coordinate system, as

may be easily shown.

140

Assuming again that the presence of the body does not

change the local hydrostatic bal-ance in the fluid, the

moment of buoyancy will be independent of the nature of

the material inside V . If the actual body is replaced by an

identical volume of the ambient fluid, this fluid volume

must be in total mechanical equilibrium, such that both the

total force as well as the total moment acting on it have to

vanish. Using that MfluidG C MB D 0, we get

and we have in other words shown that

the moment of buoyancy is equal and opposite to the

moment of the weight of the dis-placed fluid.

This result is a natural corollary to Archimedes‘ principle,

and of great help in calculating the buoyancy moment. A

formal proof of this theorem, starting from the local

equation of hydrostatic equilibrium, is found in problem.

Ship stability

Sitting comfortably in a small rowboat, it is fairly obvious

that the center of gravity lies above the center of

buoyancy, and that the situation is stable with respect to

small movements of the body. But many a fisherman has

learned that suddenly standing up may compromise the

stability and throw him out among the fishes. There is, as

we shall see, a strict limit to how high the center of gravity

may be above the center of buoyancy. If this limit is

violated, the boat becomes unstable and capsizes. As a

practical aid to the captain, the limit is indicated by the

141

position of the so-called metacenter, a fictive point usually

placed on the vertical line through the equilibrium

positions of the centers of buoyancy and gravity (the

‗mast‘). The stability condition then requires the center of

gravity to lie below the metacenter (see the margin figure).

Initially, we shall assume that the ship is in complete

mechanical equilibrium with vanish-ing total force and

vanishing total moment of force. The aim is now to

calculate the moment of force that arises when the ship is

brought slightly out of equilibrium. If the moment tends to

turn the ship back into equilibrium, the initial orientation is

stable, otherwise it is unstable.

The Flying Enterprise (1952). A body can float stably in many

orientations, depending on the position of its center of gravity. In this

case the list to port was caused by a shift in the cargo which moved

the center of gravity to the port side. The ship and its lonely captain

Carlsen became famous because he stayed on board during the

storm that eventually sent it to the bottom. Photograph courtesy

Politiken, Denmark, reproduced with permission

142

Center of roll

Most ships are mirror symmetric in a plane, but we shall

be more general and consider a ―ship‖ of arbitrary shape.

In a flat earth coordinate system with vertical z-axis the

waterline is naturally taken to lie at z D 0. In the waterline

the ship covers a horizontal region A of arbitrary shape.

The geometric center or area centroid of this region is

defined by the average of the position,

The area A of the ship in the wa-terline may be of quite arbitrary

shape.

where dA D dx dy is the area element. Without loss of

generality we may always place the coordinate system such

that x0 D y0 D 0. In a ship that is mirror symmetric in a vertical

plane the area center will also lie in this plane.

To discover the physical significance of the centroid of the

waterline area, the ship is tilted (or ―heeled‖ as it would be in

maritime language) through a tiny positive angle around the x-

axis,

such that the equilibrium waterline area A comes to lie in the

plane z D y. The net change •V in the volume of the displaced

water is to lowest order in given by the difference in volumes of

the two wedge-shaped regions between new and the old

y

6

. .

. . .

. ...

. .

..

. . . .

...

.. -

x

.

.

. A .

..

. . . . . . . . . .

. .

143

waterline. Since the displaced water is removed from the wedge

at y > 0 and added to the wedge for y < 0, the volume change

becomes

Tilt around the x-axis. The change in displacement consists in

moving the water from the wedge to the right into the wedge to

the left.

In the last step we have used that the origin of the coordinate

system coincides with the centroid of the waterline area (i.e. y0

D 0). There will be corrections to this result of order 2 due to the

actual shape of the hull just above and below the waterline, but

they are disregarded here. To leading order the two wedges

have the same volume.

The Queen Mary 2 set sail on its maiden voyage on January 2, 2004. It was

at that time the world‘s largest ocean liner with a length of 345 m, a height of

72 m from keel to funnel, and a width of 41 m. Having a draft of only 10 m,

its superstructure rises an impressive 62 m over the waterline. The low

average density of the superstructure, including 2620 passengers and 1253

144

crew, combined with the high average density of the 117 megawatt engines

and other heavy facilities close to the bottom of the ship nevertheless allow

the stability condition (3.28) to be fulfilled. Photograph by Daniel Carneiro.

Since the direction of the x-axis is quite arbitrary, the conclusion

is that the ship may be heeled around any line going through

the centroid of the waterline area without any first order change

in volume of displaced water. This guarantees that the ship will

remain in buoyant equilibrium after the tilt. The centroid of the

waterline area may thus be called the ship‘s center of roll.

145

PERTEMUAN 14

Fundamentals of Systems Engineering

14.1 Pendahuluan


a. Nasa Design Definition Process

b. Multidisciplinary Design Optimization

c. Concurrent Design Facilities (CDF)

d. Critical Design Review (CDR)



memahami Nasa Design Definition Process, Multidisciplinary Design

Optimization, Concurrent Design Facilities (CDF), Critical Design

Review (CDR)



menjelaskan Nasa Design Definition Process, Multidisciplinary

Design Optimization, Concurrent Design Facilities (CDF), Critical

Design Review (CDR)



penilaian






14.5.1 Design Solution Definition Process

146

The Design Solution Definition Process is used to

translate the outputs of the Logical Decomposition

Process into a design solution definition

Design Solution Importance

Define solution space

Develop design alternatives

Trade studies to analyze

Alternate Design

Cost, performance, schedule

Select Design Solution

Drive down to lowest level

Identify enabling products

147

Design Solution Definition – Best Practice Process Flow

Diagram

Design Solution Definition – Important Design

Considerations

148

Producibility vs. Total Cost

Concept Question

14.5.2 Multidisclinary Design Optimization

MDO defined as (AIAA MDO Tech Committee):

―an evolving methodology, i.e. a body of methods,

techniques, algorithms, and related application practices,

for design of engineering systems coupled by physical

phenomena and involving many interacting subsystems

and parts.‖

149

Conceptual Components of MDO (Sobieksi ‗97)

Mathematical Modeling of a System

Design Oriented Analysis

Approximation Concepts

System Sensitivity Analysis

Classical Optimization Procedures

Human Interface

MDO - Motivation

MDO - Roots

150

MDO - Example

Simple example of interdependency

MDO – Method: Bi-Level Integrated System Synthesis

Formulation of Design System: Supersonic Business Jet

Example

151

Subsystem Optimization (SSOPT)


152


System Optimization (SOPT)

154

MDO - Challenges

14.5.3 Concurrent design approach

to perform a system engineering study for a project. Key

elements for a CDF:

155

environment (including A/V and software)

knowledge management

Challenges in an academic environment

all project must be synchronized with academic

schedule

CDF in industrial setting

Design centers in Space Agencies

JPL: TeamX

studies have shown than cost estimations of TeamX

were within 10% of the final mission cost

rapid assessment of proposals

ESTEC (ESA)

all of the future projects at ESA are going through the

ESA CDF

Others

156

Most NASA centers, ASI, CNES, commercial

applications of the idea (painting, shipbuilding,

medical devices)

Benefits

improvements on quality for redesigned

products

very quick turnaround for ideas

better cost estimates

increased creativity and productivity in a

company

Example of Cubesat Design in J-CDS

Design of a suborbital space plane in CDF

157

Requirements

Level 1 requirements.

Reach an altitude of at least 100km over sea level

Zero G-phase flight phase of several minutes

Passenger vehicle carrying 6 people

Level 2 requirements

Safety: load limit 6 g

Spacecraft shall be controllable at any time

Customer experience: view on earth’s curvature

and atmosphere

Environment: The spacecraft’s impact on

environment should be as small as possible

Mass budget: The spacecraft’s mass should not

exceed 11.6t (with propellants)

CDF Design: K1000

158

Requirements verification by modeling

159

PERTEMUAN 15

STUDI KASUS

160

PERTEMUAN 16

UAS

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