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bd Systems, Inc.A subsidiary of SAIC

600 Boulevard South, Suite 304Huntsville, Alabama 35802

(256) 882-2650(256) 882-2683 Fax

Overview of Hypersonic Flight and Propulsion Issues

R. Steve McKamey, P.E.Prepared for the UTSI Short Course on Aero-Propulsion Systems Technology,

Test, and Evaluation

Fairborn, OHApril 23, 2008

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Who am I?

Robert S. (Steve) McKamey

BS Aerospace Engineering 1985 – University of Tennessee, Knoxville

MS Aerospace Engineering 1991 – University of Tennessee Space Institute

Test Engineer – Aeropropulsion Systems Test Facility (ASTF) Arnold AFB 1985-1990

Facilities Engineer – Arnold AFB 1996-1999

Space Systems Engineer – NASA MSFC 2000 – present

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Short History of Hypersonic Flight

• 1950 – Hermes II Airbreathing Missile

• 1960 – Eugen Sänger Airbreathing TSTO

Drawing: US Army

Artists Rendition: Joel Carpenter

Artists rendition: Mark Lindroos

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Short History of Hypersonic Flight

• Hypersonics in Germany– Aachen 4-inch blowdown tunnel (Mach 3.3)– Peenemunde 16-inch blowdown tunnel (Mach 4.4)

• Vacuum sphere diameter of 40 feet• Run times of 20 seconds• Problems with condensation and constructing high-speed

nozzles• Special test with Mach 8.8 nozzle and compressed (90

atm) air on the intake side – first Hypersonic wind tunnel test (by Mach 5 definition)

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Short History of Hypersonic Flight

• Hypersonics in Germany (cont)– Eugen Sänger “Silverbird“ ()

Antipodal Bomber• First hypersonic spaceplane

concept

• Used Atmospheric skipping maneuver to reach targets in the United States

• US and Soviets studied this design with much interest in the postwar period

• Stalin’s son sent to France to kidnap Sänger

http://greyfalcon.us/pictures/

Sang1.jpg

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Short History of Hypersonic Flight

• 1959 – X-15

• 1962 - 1978 Soviet Spiral 50-50

Spiral 50-50 Artists rendition: Credit - © Mark Wade

http://www.dfrc.nasa.gov/Gallery/Photo/X-15/Small/EC67-1731.jpg

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Short History of Hypersonic Flight

• 1964 Boeing X-20 Dynasoar

Credit: USAF

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Short History of Hypersonic Flight

• 1990 National Aerospace Plane X-30 – Hypersonic, Air-breathing,

SSTO– Highly integrated

inlet/engine/nozzle with the airframe

– Technological hurdles• High temperature

materials

• Supersonic combustors

• 300 mph tires

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NASP

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Short History of Hypersonic Flight

• 2004 NASA X-43 – Air-launched, Mach 7-10,

Hypersonic Air-breathing test vehicle

– Two successful flights• Mach 7 & Mach 10

– Demonstrated Scramjet propulsion

X-43 Vehicle

Credit: NASA

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Characteristics of Hypersonic Flow

• Airflow speeds high enough to cause real gas effects, i.e. ionization and dissociation.

• M∞ > 4.0 – 5.0

• Wall heat transfer effects become very important

• Equilibrium chemistry no longer applies

• Rarefied flow (non- continuum)

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Hypersonic Airbreathing Propulsion

0 205 10 2515

2500

5000

500

Subsonic CruiseTurbofan

Flyback

Landing

ScramjetAir-Augmented

Rocket

Ramjet

RocketLow-Earth

Orbit

Ne

t-Je

t S

pe

cific

Im

pu

lse

(se

c)

Mach Number

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Brayton Cycle

• Ramjets and Scramjets operate on the Brayton Cycle

P0

P2

0

2

3

INLET

COMBUSTOR

NOZZLE

Tem

per

atu

re

Entropy

4

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Brayton Cycle

Credit: S.I Chernyshenko University of Southhampton SESA 2005 Propulsion Lecture notes.

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Ramjets

• Operate from Mach 1.5 ~ Mach 6

• Supersonic external compression

• Subsonic internal flow

• Subsonic combustion

• C-D nozzle expands flow back to supersonic

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Ramjets

• Add diagram here

Flameholders

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Ramjets

X-15 fitted with pylon-mounted ramjet engine and external fuel tanksCredit: NASA

Dummy Ramjet

NASA tested the dummy ramjet in preparation for live tests of the ramjet engine from speeds of Mach 4 – Mach 8. The vertical fin was badly damaged during the carry testing and the X-15 program was cancelled before the live fire flight tests could be accomplished

Credit NASA

The pink coating in this picture is an ablative silicone-based elastometric thermal protection coating. This X-15 was to be flown past its Mach 6.6 design point so it had to have better thermal protection.

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Ramjets

The Mach 2.5+ Coyote target passing over the bow of a Navy ship midway through a 100 km flight that was conducted on 22 April 2005

Credit: AFRL PROPULSION DIRECTORATE Monthly Accomplishment Report April 2005

US Navy GQM-163 “Coyote” Target Drone

Credit: Orbital Sciences Corp.

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Ramjets – GQM 163A Coyote

Source: Orbital Sciences Corporation Fact Sheet

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Scramjet Propulsion

Credit: NASA

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Scramjet Cycles

2A

Ent

halp

y

Entropy

C

B

A

P∞

P2C

P3B

P2C

P2A

4A

4B

4C3B

6′A 6′B6′C2B

Credit: Marquardt

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0 8 10 122 4 6

80000

40000

Alt

itu

de

(f

t M

SL

)

DUAL MODE RAMJET

SUBSONIC BURNING RAMJET

SCRAMJET

160000

120000

Freestream Mach Number

Dual Mode Range of Operation

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Definitions – Specific Impulse

2

10 ln m

mgIV sp

T

D

T

WII speff

sin1

Ideal Rocket Equation

Effective Specific Impulse

Equivalent Effective Specific Impulse

effIdvV

I *

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Airbreathing Launch Vehicles

• Advantages– LO2 is up to 84% of propellant weight in

rocket-powered launch vehicles– TSTO airbreathers could include flyback

booster stage (reusability)

• Disadvantages– Large wings for horizontal takeoff (high drag

consumes efficiencies)– Low payload mass fractions

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Issues: Heat Addtion

• Heat addition places limits on subsonic combustion– Temperature of combustion products equal

with inlet recovery temperature at some point– Melting materials places limits lower than the

above– Keeping internal static temperatures low

enough that heat addition is practical at high mach numbers is only possible through supersonic combustion.

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Issues: Heat Addtion

00 2 4 6 8 10 12

1000

2000

3000

4000

5000

6000

7000

Inlet Recovery Static Temperature

Products of Combustion

Credit: Hill and Peterson

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Issues - Inlet Starting

Characteristics of a Started Inlet

• Cowl shock attached to cowl lip

• Static pressure rises steadily

• maximum mass flow capture

• Flow is steady

Characteristics of an Unstarted Inlet

• Cowl shock stands out ahead of the cowl and is unattached

• Static pressure has a marked decline followed by a rise

• Mass spillage around the cowl lip

• Flow may be oscillatory

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Inlet Starting

Schlieren Image of a Started Inlet, M = 4.0Ref: Smart, Michael K. and Carl A. Trexler, Mach 4 Performance of Hypersonic Inlet withRectangular-to-Elliptical Shape Transition, AIAA JOURNAL OF PROPULSION AND POWERVol. 20, No. 2, March–April 2004, pp 288 -293

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Inlet Starting

Schlieren Image of an Unstarted Inlet, M = 4.0Ref: Smart, Michael K. and Carl A. Trexler, Mach 4 Performance of Hypersonic Inlet withRectangular-to-Elliptical Shape Transition, AIAA JOURNAL OF PROPULSION AND POWERVol. 20, No. 2, March–April 2004, pp 288 -293

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Issue: Boundary Layer Ingestion

Characteristics of Hypersonic inlets :

• Very Long

• High Reynolds Number

• Multiple Compression Shock Waves

• Adverse Pressure Gradient

All of these are ideal conditions for….

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Boundary Layer Ingestion

Airframe Forebody Ramp

Inlet Cowl

Forebody Boundary Layer Growth

Bow Shock

At higher Mach numbers, the boundary layer can obscure as much as 40% of the capture area of the inlet

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Issues: Fixed vs Variable Geometry

• Wide range of flight conditions makes variable inlet geometry attractive– Engines designed to operate at a single

design point freestream dynamic pressure– Inlets desired to provide steady flow

conditions over a range of Mach numbers (2 -12+)

– Due to the scale of the inlet and compression ramp, variable inlet geometry has the potential for a very large dry mass penalty

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Air-Augmented Rockets

LOX-RP-1 First stage Concept from NASA Advanced Systems Office circa 1967

This stage concept employs eight H-1 engines, six of which are installed in the air augmentation ducts. The two remaining H-1's are located in the boattail in order to provide thrust vector control.

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Case Study: GTX

Credit: NASA

GTX Combined Cycle SSTO Launch Vehicle

• Rocket – Ramjet -Scramjet –Rocket

• Liquid Hydrogen Fuel

• GLOW = 1,248,213 lbm

• Payload = 25,000 lbm

• Design Dynamic Pressure = 2000 psf

• Design Orbit to ISS (220 nmi x 220 nmi @ 51.6° inclination)

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GTX Combined Cycle Propulsion

Mode 1 Liftoff to Mach 2.5 – Engine Operates as an Air-Augmented Rocket

Mode 2 Mach 2.5 – 5.5 , Engine Operates as a Thermally Choked Ramjet

Ref: NASA TM 2002-211495

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GTX Combined Cycle Propulsion

Mode 3 Mach 5.5 – Mach 11 Engine Operates as a Supersonic Combustion Ramjet (Scramjet)

Mode 4 Mach 11 - Orbit, Engine Operates as a Pure Rocket

Ref: NASA TM 2002-211495

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Case Study: GTX

Credit: NASA

9

25 Klbm Concept Vehicle

Rocket Transition at M = 10+

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Other Card Tricks

• Virtual Wing– If your ABLV doesn’t have enough lift to take

off horizontally, give it a virtual wing – all lift, no weight and no drag

• Virtual Propellant– Scramjets can fly efficiently at much lower

dynamic pressures using virtual oxidizer. Virtual propellants also have no mass and do wonders for vehicle performance closure.

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Conclusions

• Despite X-43, Scramjets are a low-TRL (3-4) technology

• Still need to demonstrate positive thrust over a range of operating conditions.

• Still need to demonstrate transition from subsonic to supersonic combustion

• High temperature materials are needed to allow higher combustion chamber and leading edge temperatures

• Better understanding of supersonic combustion stability

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References

• Heppenheimer, T. A., Facing the Heat Barrier: A History of Hypersonics, NASA SP 2007-4232, Washington D.C., September 2007

• Hill, Phillip G., and Peterson, Carl R., Mechanics and Thermodynamics of Propulsion, Reading, Massachusetts, Addison-Wesley, 1965

• Shapiro, Ascher H., The Dynamics and Thermodynamics of Compressible Fluid Flow, New York, Ronald Press Company, 1953

• Escher, W.J.D, and Flornes, B.J., A Study of Composite Propulsion Systems for Advanced Launch Vehicle Applications, Main Technical Report, Volume 2., NASA Contract NAS7-377, April 1967

• Supersonic Combustion Technology, Report S-447, Marquardt Corporation, Van Nuys, California, November 1964

• The Synerjet Engine, SAE PT-54, Society of Automotive Engineers, Warrendale, Pennsylvania, January 1997

• Foster, Richard W., Escher, W.J.D., and Robinson, J.W., Air Augmented Rocket Propulsion Concepts, AFAL TR-88-004, Astronautics Corporation, Madison, WI, April 1988

• Trefny, Charles J., Roche Joseph M., Performance Validation Approach for the GTX Air-Breathing Launch Vehicle, NASA TM-2002-211495, NASA Glenn Research Center, Cleveland, OH, April 2002

• Encyclopedia Astronautica: http://www.astronautix.com

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