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Running head: MORE-ELECTRIC CIVIL AIRCRAFT: A STUDY ON BOEING 787

MORE-ELECTRIC CIVIL AIRCRAFT: A STUDY ON BOEING

787

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MORE-ELECTRIC CIVIL AIRCRAFT: A STUDY ON BOEING 787

The design of the future aircrafts has been seen to evolve in accordance with the increase in

reliability on the electrical systems. This excessive reliance on electrical systems has facilitated the birth

of More-Electric Aircrafts (MEA), which has embraced itself with the emerging notions in terms of the

number of critical electrical load. Furthermore, this significant alteration in terms of the governing system

subsequently spread considerable impact on the rest of the design drivers that encourages for concise and

robust civil aircraft design. The moot target, which contemporary aircraft designers cater, is to merge the

reliability with the available options that might exhibit a significant enhancement of the overall efficiency

of the civil aircraft while proposing alternative design architectures. Several apprehensions suggested that

this emerging inclination of reliability could be further enhanced through the systematic use of back-up

generation and redundancy.

The current study suite is supposed to investigate the regulatory justifications of this

embracement of more-electric aircrafts with the potential impacts on their absolute efficiencies coupled

with a brief description of Boeing 787, which happens to be the first MEA in the history of civil aircrafts

of electrical systems. Moreover, the study caters the systematic evaluation of the prevalent design drivers

of a civil aircraft against the proposed MEA ones. Apart from all of that, this study desires to reflect

certain fecund anticipation regarding the design architecture of the civil aircrafts of future.

Figure 1: Overview of the concept of MEA

Source: (Denning, 2013)

Explanation of “more” electric against the enhanced efficiency of the AircraftBefore the advent of electrical systems, the civil aircrafts are designed based upon the

conventional design architecture, which happens to assemble mechanical, hydraulic, electrical and

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pneumatic resources of power generation in order to propagate itself. In this architecture, the control fuel

is supposed to be transformed into propulsive power that facilitates the mobility of the aircraft. The fuel

leftover is fed into a intricate system of the corresponding components that are supposed to provide the

non-propulsive power to the aircraft(Huber, 2014). The considerable intricacy of the ensemble has been

discovered to impart adverse impact in the absolute efficiency of the aircraft since a nominal leak in the

comprising components might pave the aircraft towards network outages and consequent flight delays

coupled with the inconvenience to locate the fault at once.

Though we intend to talk about more-electric aircrafts in the current context, the proclivity of the

contemporary design architecture is to develop all-electric aircraft, which is systematically devoid of the

burden of the intricate ensemble of the non-electric components. This trend is destined to endow the

prevailing aircraft design with the freedom from bleed air off-takes and on-engine hydraulic power

generation, which altogether supplements the absolute efficiency of the aircraft while encouraging the

development of high-voltage electrical networks for non-propulsive power generation. In order to respond

to the respective for high-voltage electrical networks, bleed-less systems of air-conditioning, innovative

fuel cells, variable frequency generators and intricate embedded digital distribution systems have been

intended to integrate with the prevalent architecture in order to facilitate the birth of MEA’s.

Figure 2: Layout of MEA DC Power System

Source: (Abdel-Fadil, 2013)

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On a general note, the attempts that have been incorporated in the proposed architecture of MEA’s

are supposed to enhance the prevalent absolute efficiency through;

● Eliminating the prevalent hydraulic and air engines

● Significantly enhancing the capability of power generation

● Installing fecund electrical networking methods that might facilitate the ability of fault

identification and protection

● Proposing electromechanical actuators as a potent alternative of hydraulic actuators

● Reduction in weight and space in order to decrease production and maintenance cost

The chief challenge that the architecture designers are supposed to cater is the rationalization of the

available power sources and existing networks among the ensemble in order to device a bleedlessengine

with a propulsive thrust of 40MW. Furthermore, electrically operated generators are supposed to fuel the

pumping engine auxiliaries while enabling the civil aircraft with landing gears with flight control

actuation better known as Braking Doors(Huber, 2014). Apart from that, the proposed system is supposed

to cater the power requisite regarding the cabin pressurization.

Figure 3: Conventional Power Distribution

Source: (Huber, 2014)

● Elimination of the hydraulic system consequently endow the architecture design with reduced

system weight while providing a relative ease in the overall maintenance

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● The concept of bleedless engine is supposed to supplement the most to the cause of improved

efficiency

● Enhancement of controllability endowed the design with unimpeded access to power in the times

of high demand

● The ancillary characteristic of re-configurability is destined to retain the core functionality during

major faults

● The new design seem to incorporate considerable advancement in prognostics and diagnostics

that consequently emancipates the availability of aircraft while promising intelligent

maintenance

Figure 4: Power distribution layout in MEA

Source: (Gao, 2017)

The overall impact can be summarized as;

● Considerable reduction in environmental impact

● Considerable reduction in the amount of fuel burn

● Considerable impact in the operating costs

Brief Introduction of Boeing 787As it was mentioned earlier in the introductory phase, the Boeing 787 happens to be the

first civil aircraft, which contains nascent characteristics of a MEA aircraft. As per the empirical

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specifications provided by the Boeing Commercial Airplanes, it is an American jet airliner with

twin-engines along with long haul and mid-size wide body(Gao, 2017). It is the first airliner with

three-class seating arrangements with a composite airframe and conditioned to 20% efficient

than the previous model of Boeing 767 in terms of fuel consumption(Wang, 2016). The distinct

features of this airliner is mostly operated by electrical systems with raked wingtips and chevrons

in the nacelles of two of the engines which are designed to reduce the noise considerably.

Figure 5: Overview of Electrical system of Boeing 787

Source: (Gao, 2017)

The electrical system flight operating system typically consists of;

● 4 x 250killo Volt-Ampere primary channel starter generators with 500k-VA capacity per

channel

● 230VAC primary power generation (VF)

● Electrical starter & generators with full-load rating of 250/225k-VA

● Electric Environmental Control System with wing anti-Icing and pressurization

● It happens to be the first twin-engine Jet liner which is literally bleedless

Despite several in-service disruptions regarding the incorporation of lithium-ion batteries that

facilitates the setting of fire, it is one of the foremost exponents in the advent of MEA’s.

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Brief Description of the new system architectureEngine Systems

The engine systems of a civil aircraft are often described by the mechanical properties in

the fecund discourses of the underlying context. In the prevalent architecture of designs, the

mechanical properties are supposed to feed fuel to the governing engine from the local oil

pumps. This has been accomplished by the means of mechanical gearboxes which is conditioned

to propagate the fuel towards the central hydraulic pump and such other mechanically-driven

subsystems along with the governing electrical generator. The emerging trends of the latest all-

electric system is supposed to employ electro-mechanical actuators instead of the conventional

ones that might facilitate the easy integration of the cardinal components of the actuation

ensemble while reducing the amount of absolute fuel burn(Denning, 2013).

Figure 6: Direct Drive Architecture MEA

Source: (Huber, 2014)

Bleed air Systems

Bleeding might refer to the leakage of fuel, which is supposed to be governed by the

pneumatic systems prevailing to the conventional design architecture. In general, this power for

non-propulsive thrust is typically derived from the high-pressure compressors, which are

conditioned to provide power to the Environmental Control System (ECS) and to provide hot air

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to serve the3 purposeof Wing Anti-Icing (WAI). This system is considered to be the element,

which causes the massive reduction in terms of efficiency due to the sheer incapability to discern

leaks. The notion that the contemporary design architects serve is to device a civil aircraft which

is literally bleedless(Gao, 2017).

Figure 7: Regeneration Converters

Source:(Baker, 2014)

Hydraulic Systems

These systems are conditioned to transmit the hydraulic power from the central hydraulic

pump towards the embedded actuation systems that subsequently facilitates the seamless primary

and secondary flight control. Moreover, this robust system with high power density is supposed

to command the landing gear for employment, braking, retraction and engine actuation and

several other auxiliary services. The flagrant drawbacks that it consists are the inflexible piping

infrastructure, which facilitates the chances for leakage since the control fluids are corrosive in

nature(Baker, 2014). The proposed architecture of the new MEA aircrafts are supposed to

provide a potent substitute of the actuation system that can enable the aircraft to operate in a

leakage-free atmosphere with increased access in the controllability while ensuring the feasible

characteristics of the electrical systems.

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Figure 8: Actuation system in MEA’s

Source: (Gao, 2017)

Electrical Systems

These systems are supposed to endow the entire aircraft with the power amenities serving

the power requisites regarding the avionics, galleys, illumination and several other commercial

loads that are supposed to feed the entertainment systems. The apprehensions regarding the

flexibility consolidates the pursuit of “all-electric aircraft” since it is inherently devoid of a heavy

infrastructure while having a considerable flexibility in the entire structure. The potential

drawback of inherent low-power density needs to be mended by deploying high-voltage

electrical networks that might feed the entire ensemble of embedded distribution.

Figure 9: Nascent trends of MEA

Source: (Denning, 2013)

Summary TableDesign Architecture Conventional Aircraft MEA Aircraft

Electrical Systems These systems are supposed to The apprehensions regarding

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endow the entire aircraft with

the power amenities serving

the power requisites regarding

the avionics, galleys,

illumination and several other

commercial loads that are

supposed to feed the

entertainment systems.

the flexibility consolidates the

pursuit of “all-electric

aircraft” since it is inherently

devoid of a heavy

infrastructure while having a

considerable flexibility in the

entire structure.

Hydraulic Systems These systems are conditioned

to transmit the hydraulic

power from the central

hydraulic pump towards the

embedded actuation systems

that subsequently facilitates

the seamless primary and

secondary flight control.

Moreover, this robust system

with high power density is

supposed to command the

landing gear for employment,

braking, retraction and engine

actuation and several other

auxiliary services.

The proposed architecture of

the new MEA aircrafts are

supposed to provide a potent

substitute of the actuation

system that can enable the

aircraft to operate in a

leakage-free atmosphere with

increased access in the

controllability while ensuring

the feasible characteristics of

the electrical systems.

Bleed Air Systems In general, this power for non-

propulsive thrust is typically

derived from the high-pressure

compressors, which are

conditioned to provide power

to the Environmental Control

System (ECS) and to provide

This system is considered to

be the element, which causes

the massive reduction in terms

of efficiency due to the sheer

incapability to discern leaks.

The notion that the

contemporary design

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hot air to serve the3 purposeof

Wing Anti-Icing (WAI). This

system is considered to be the

element, which causes the

massive reduction in terms of

efficiency due to the sheer

incapability to discern leaks.

architects serve is to device a

civil aircraft which is literally

bleedless

Engine Systems This has been accomplished

by the means of mechanical

gearboxes that is conditioned

to propagate the fuel towards

the central hydraulic pump

and such other mechanically-

driven subsystems along with

the governing electrical

generator.

The emerging trends of the

latest all-electric system is

supposed to employ electro-

mechanical actuators instead

of the conventional ones that

might facilitate the easy

integration of the cardinal

components of the actuation

ensemble while reducing the

amount of absolute fuel burn

Estimated outlook of the next generation AircraftAs it was already mentioned in one of the prevailing segments of the entire study suite

that the civil aircraft of the future intends to let itself operated through a system governed by

electrical means. The infrastructural flexibility that the all-electrical system is supposed to endow

the operating system with is due to the elimination of the governing design drivers of prevalent

system, which, in return, is conditioned to affect the absolute efficiency adversely. Only

advantage that the conventional system has to provide is the high power-density due to which all

the non-propulsive power purposes and the commercial demands has been fed with the electrical

systems(Abdel-Fadil, 2013). The discovery and subsequent development of solid-state power

with enhanced reliability and high power density is considered to be the milestone which caters

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the underlying pursuit while mitigating the only drawback of the system entirely driven by

electrical measures. The next generation civil aircraft celebrates the possibility of integrating

high voltage embedded systems of power distribution that might enable the aircraft with a

flexible yet robust power infrastructure while emancipating the absolute efficiency.

ConclusionThe significant advent of technological expertise that led to the practice of solid state and

reliable power electronics have ensured the leap in the architectural design of civil aircrafts.

Though it has been extensively mentioned in some of the scholarly articles of the underlying

disciplines that Boeing 787 happens to be the first civil aircraft to embrace the More-electrical

approach is a sheer under specification since the military aircraft designers have pursued the

dream of much-coveted “all-electric” aircraft in the verge of World War II. The reason of not

being successful is the unavailability of the electrical systems with such infrastructural flexibility

while having a high power density to ensure unimpeded distribution of propulsive and non-

propulsive power. From the end of 1990’s when the researchers have been able to prove the

fecundity of reliable solid-state power electronics to encourage a high-voltage embedded system,

an “all-electric” civil aircraft has yet to be designed.

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