AC 2010-2270

UNDERGRADUATE STUDIES OF SUPERSONIC TRANSPORT DEVELOPMENT

Narayanan KomerathDaniel Guggenheim School of Aerospace Engineering

Georgia Institute of TechnologyAtlanta

PROJECT EXTROVERT: Learning To Innovate Across Disciplines

McMahon Solutions LibraryMcMahon Solutions Library

Skills LibrarySkills Library Design-

Centered Introduction

Design-Centered

Introduction

FluidsFluids

PhysicsPhysics

ChemistryChemistryThermalSciencesThermalSciences

MaterialsMaterials

Elasticity

Strength

Composites

LowSpeedGasdynamicsHighSpeed

PropulsionPropulsion

Controls

System DesignSystem Design

Engg. Disciplines

Engg. Disciplines

Public PolicyPublic Policy

Social Sciences

Social Sciences

Space ScienceSpace

Science

Core Subject Knowledge

Case Studies Library

Case Studies Library

Advanced ConceptsAdvanced Concepts

Project Structure for EXTROVERT: Learning To Innovate Across Disciplines.

U R HereU R Here

Exercise in challenging “conventional wisdom” and taking a fresh look at a global challenge problem.

Aim:

Make supersonic airline travel viable for the mass market.

Approach:

Concept Development Exercise

•Conceptual design at several levels, combining technical knowledge with global demographics, economics, sustainability and public policy issues.

•Validate calculations by confirming present day conclusions, then challenge assumptions and show alternative path to viability.

•Go from requirements definition to “ticket price per seat mile”

•Refine technical design and economics

High-Speed Civil Transport (HSCT)Why did the NASA-Boeing-GE-UTC effort fail?

An HSCT would reduce the flight times from California to Japan to approximately 4 hours

Lets see some slides from NASA’s final report on the HSR program. Source: NASALets see some slides from NASA’s final report on the HSR program. Source: NASA

Aeronautics R&T“Three-Legged Stool”

Policy Supportability

Market AcceptabilityTechnology Availability

Source: NASA

Organization of this presentation

•Introduction to the project

•5 different levels at which concept development has been pursued.-AE1350 Freshman Introduction to Aerospace Engineering-AE3021 High Speed Aerodynamics-AE2xxx Special Problems-AE4xxx Special Problems- Undergraduate thesis

•Technical issues & results

•Observations regarding evolution of student experience

•Conclusions

•Acknowledgements

AE1350 Freshman Introduction to Aerospace Engineering

2 hour freshman course, taught in Spring 2010. Several prior teachings since 1997, using Conceptual Design as the gateway to aerospace engineering.

Major assignment, done in teams of two:

Conceptual design of a short-haul (~1000 mile range) subsonic airliner to carry 150 passengers. Spreadsheet calculation procedure, with range and structurefraction used as metrics of viability.

Revise to incorporate liquid hydrogen fuel. Compare performance of the two versions. Calculate lifecycle carbon savings at today’s Carbon Market prices.

• Designing a Flight Vehicle: Road Map• Force Balance During Flight• Earth's Atmosphere• Aerodynamics• Propulsion• Performance• Stability and control• Structures and Materials• High Speed Flight• Space Flight

• For given specifications, estimate payload using common sense (e.g., “What is the average weight of a passenger on an airliner? How much food and water should be carried per passenger?”)

• From benchmarking guess Payload Fraction. Find Take-Off Gross Weight.

• Wing Loading from benchmarking, find planform area. Fix span, find Aspect Ratio.

• For selected cruise altitude and speed, find CL and CDi.

• Guess low speed CD0. Find cruise L/D and Speed for Minimum Drag.

• Use thumb-rules to select a suitable engine and number of engines.

• For the selected engine, find thrust-specific fuel consumption from published data, and estimate thrust at altitude.

• For specified range, find the fuel weight fraction needed at takeoff.

• Given engine thrust-to-weight ratio, see if structure weight fraction is enough to build the aircraft.

• Once the cruise point design is shown to close, find the steady flight envelope, against aerodynamic stall, thrust available, and maximum climb rate.•Find takeoff and landing distances.

Implemented on spreadsheet for iteration, integration and plotting.

Conceptual Design at Freshman Level

GLOBAL DEMOGRAPHICS AND AIRLINE ROUTES

Final 3-hour core course in aerodynamics/fluid dynamics/gas dynamics, following 3 hours of AE2020, Low Speed Aerodynamics, and 4 hours ofAE3450, Thermodynamics and Gas Dynamics.

Compressible potential flow for subsonic and supersonic aerodynamics. Shock/expansion analyses, compressible boundary layer calculations.

Major Assignment (teams of 2): Select an airplane configuration and analyze one subsonic and one supersonic design point, calculating lift to drag ratio without resort to CFD.

Used Sears-Haack body and compressible boundary layers to estimate minimum drag for supersonic aircraft.

AE3021 High Speed Aerodynamics

AE 2xxx and 4xxx Special Problems

2 sophomores (alumni of AE1350, Spring 2010) and 3 seniors (all following completion of Aircraft Design capstone design course, 2 after AE3021 as well)signed up for 3-hour Special Problems, across 2 semesters.

1 other student signed up for an Undergraduate Thesis project.

Questions for consideration by undergraduates:

• Drag implication of using hydrogen, given lower fuel weight fraction

• Effect of post-1990 demographics and economics on market projections

• Viable destinations, flight times, curfew and business implications

• Impact of Global Warming/ Carbon emission reduction initiatives • Noise implications of hydrogen-powered SST?

• Radical concepts to take advantage of the different features of hydrogenfuel, supersonic flight, and airport logistics

Summary of Issues

Technical issues & results

Issue #1: Lack of market. No incentive to build SST, because the passengers wouldbe the same ones who now pay for first/business class tickets that make transonicairline routes profitable.

Response: Post-1990 changes in air routes, global demographics and economics.

Issue #2: SST not viable in 1960s, certainly not viable today with high fuel prices.

Response: True for hydrocarbon-fueled SST. Not viable at all.

Issue #3: LH2 requires large volume causing unacceptable supersonic body drag.

Response: Not true. Large improvement in payload fraction due to high heating valueof H2 means that the airplane is much lighter, and hence drag is not higher.

Issue #4: Mach 2.5+ flight requires advanced materials. M<1.7 is inefficient.

Response: M>1.4 not needed for mass market. Overall architecture is efficient at 1.4 Sears-Haack transonic drag estimate provides upper bound for ideal drag.

OBSERVATIONS REGARDING EVOLUTION OF STUDENT EXPERIENCE

1. Conceptual Design Procedure: Freshmen comfortable and pick up quickly. 2. Project Document for the conceptual design project to counter “last-minutitis”.3. Cross-disciplinary exploration comes easily for freshmen, harder for seniors!4. Basic knowledge issues persist with seniors and graduate students. 5. Implementation Experience: • Undergraduate thesis student decided that taking courses was easier.• Taking advanced courses confuses students! Only a few build the trait of

thinking about the methods that they learn. • Students from AE3021 and Capstone Design reluctant to use simple conceptual

design process given in AE1350. Eventually realized that their complex formulae gave the same results when used correctly.

• When faced with unacceptable numbers, hesitant to do anything about it! (L/D <3 – but “only in cruise”!) AIAA Student Conference paper withdrawn.• Poster prepared and discussed with better results. • Paper to peer-reviewed conference done successfully.6. Vertical Integration aspects: After enough iterations, and given examples,

students do pick up and do an excellent job.

Overall design calculations

Market / demographics issues

Applying “theory” learned in classes

Capturing essence of design approach

Using math to develop bounds

SUMMARY OF OBSERVATIONS

1. Multilevel process to explore a high-risk concept using undergraduate participants.

2. Vertical and horizontal knowledge integration aspects explored, with differing levels of success and difficulty.

3. Simple conceptual design procedure permits students to explore advanced aircraft

concepts and see what is needed to make the design close.

4. Process then used as starting point for detailed configuration analysis.

5. Conclusions on the LH2 SST:

• Huge change in Eastern Hemisphere demographics, politics and economics

• Large rise in engine T/W and drop in TSFC since Concorde days

• Fossil-fuelled SST is still not viable at today’s fuel prices

• LH2 drag penalty is absent, due to large gain in payload fraction.

• LH2 becomes more attractive as fossil costs rise and H2 costs decrease.

• LH2 SST development costs can be partially met by carbon market savings.

6. Opportunities to improve depth and breadth of learning, and project performance.

7. Iteration helped students reach a good level of project completion.

CONCLUSIONS

ACKNOWLEDGEMENTS

The work reported in this paper was made possible by resources being developed for the “EXTROVERT” cross-disciplinary learning project under NASA Grant NNX09AF67G S01. Mr. Anthony Springer is the Technical Monitor.

Valuable technical resources on high speed aircraft aerodynamics came from the Boeing Company, courtesy of Dr. B. Kulfan.

Potential HSCT Economic Impact - 1990 View2005-2020 Long Range Over-Water Market

Long range airplane market share could be driven by HSCT

Potential for a $200B swing in U.S. sales and 140,000 new jobs

U.S. HSCT Program Offshore HSCT Program

Subsonic Only — No HSCT

HSCT European Team

LargeSubsonic

MediumSubsonic

Medium & Large

Subsonic

HSCT U.S.

Team

LargeSubsonic

MediumSubsonic

Medium & Large

Subsonic

LargeSubsonic

MediumSubsonic

Medium & Large

Subsonic

United States

79%

United States( 747 / 767 / 777MD-11 / MD-12 )

65%

United States

49%

Europe

21%

Europe

51%

Europe( A300 / A330 /

A340 )

35%

High-Speed Civil TransportComparative Perspective

Concorde HSCT Goals

North Atlantic

1976

2.0

3000

100

400,000

87

Premium

Exempt

75

20a

Market

Entry In Service Year

Cruise Speed (Mach)

Range (nautical miles)

Payload (passengers)

Takeoff Gross Weight (lb.)

Required Revenue (¢/RPM)

Fare Levels

Community Noise Standard

Noise Footprint (sq. mile)

Emissions Index (gm/Kg fuel)

Atlantic & Pacific

2005

2.4

5000 - 6500

250 - 300

700,000

10

Standard

FAR 36 - Stage 3

5

5

Source: NASA

High-Speed Civil Transport DevelopmentBusiness Implications

• Studies by Industry have Indicated that HSCT Development Costs Could be more than Twice the Level of Current Subsonic Airplanes

• If the Product is Successful:– Industry will Face 15-18 Billion Dollar Negative Cash Flow with a Break

Even in the 7 -10 Year Range assuming Continuous Production• If the Product is Unsuccessful:

– High Development Costs and Investments would be Unrecoverable– The Ability to Compete for Advanced Subsonic Airplane Sales would be

Significantly Degraded– Significant Impact to Market Share and Balance of Trade

These Technical and Economic Risks Make it Unwise to Commit to a Product Development Program without a Clear Demonstration of Technical and Cost Viability

Source: NASA