1. Introduction to Hypersonic Propulsion Systems
Dr. Andrew Ketsdever
Assistant Professor
Department of Mechanical and Aerospace Engineering
University of Colorado at Colorado Springs

2. Technology Requirements

3. Propulsion System Factors
Efficiency
Weight
Complexity
Variability
Longevity and cost of components
Fuels (density, rheology, stowability, handling, combustion characteristics, cost)
Materials
Mission requirements (trajectory, cost, etc.)

4. Selection Process

5. Performance Specific impulse Thrust Inert mass fraction
All three must be optimized in order to achieve desired outcome

6. Performance

7. Materials Temperature Small Space Booster Thrust NASP Chambers Boost
Solid
Staged
Combustion
Time, sec
Liquid
Rocket
Engine
Nozzles
Satellite
Propulsion
Cruise
Missiles
Boost
Glide
Vehicles
Thrust
Chambers
NASP
Temperature

8. Fuels

9. Problems
Most launch vehicles are rockets, which suffer from low specific impulse compared with air-breathing systems (5000 sec. for turbojets vs. 500 sec. for rockets)
This degrades overall performance and increases weight (a good reason to investigate hybrid systems for future launch vehicles!)

10. Problems
The need to carry so much fuel makes overall weight a crucial design factor
The structure of the vehicle is made as light as possible to compensate
Boosters are not strong, rigid bodies. While they are fairly strong longitudinally, they are very weak laterally
Most rockets cannot fly at significant angles of attack through the atmosphere or they would fall apart!
A rocket carrying satellites usually starts vertically, but must end in a horizontal orbit trajectory
How can you control trajectories???
How do you keep from falling apart???

11. Pratt & Whitney J58 Turbo-ramjet cycle
35,000-lb thrust class, 9-stage compressor, SFC /hr

12. Flight Regimes FLIGHT MACH NUMBER ALTITUDE, KFT 1 2 3 4 5 6 7 200 150
SUBSONIC TURBINE ENGINE
HIGH ALTITUDE SUPERSONIC TURBINE ENGINE
RAMJET, AIR-AUGMENTED ROCKET
LOW ALTITUDE SUPERSONIC TURBINE ENGINE
HYPERSONIC RAMJET
150
ALTITUDE, KFT
100 50 1 2 3 4 5 6 7
FLIGHT MACH NUMBER

13. Propulsion Options Scramjet Combined cycle Propulsion
“Low speed” cycle + scramjet
Rocket Based Combined Cycle (RBCC): Mach air-breathing +rocket + scramjet + rocket
Turbine Based Combined Cycle (TBCC): Mach 0--4, 5 turbine + scramjet
Scramjet
Supersonic combustion ramjet
Hydrocarbon (Mach 3-8)
Hydrogen (Mach 3-15)

14. Scramjet Body Combustor Isolator Inlet
Vehicle and Propulsion system are totally integrated
No Moving Parts Necessary
Mach 4 and higher
Body
Fuel
Cowl
Combustor
Forebody
(Compression)
Nozzle
Shock Wave
Isolator
Inlet

15. NASA X-34 Scramjet Program
"On 16 November, 2004, NASA's unmanned Hyper-X (X-43A) aircraft reached Mach 9.6 (~7,000mph). The X-43A was boosted to an altitude of 33,223 meters (109,000 feet) by a Pegasus rocket launched from beneath a B52-B jet aircraft. The revolutionary 'scramjet' aircraft then burned its engine for around 10 seconds during its flight over the Pacific Ocean."

16. Turbine Based Combined Cycle (TBCC)
Accelerator Turbine (Mach 0—4.3) is combined with a duel-mode scramjet engine (Mach 4—8)
Transition from turbine power to ramjet is performed at Mach 4
Over-Under configuration
Accelerator Turbines
Turbine-engine inlets
Cocooning hot turbine engines will be a technical challenge
Tail rockets would likely be added if vehicle is the first stage of launch system

17. Rocket Based Combined Cycle (RBCC)
Rocket-Based Combined Cycle promises a propulsion system that can achieve good performance from M = 0--25
Body
Strut &
Rockets
Cowl
Combustor
Forebody
(Compression)
Nozzle
Inlet &
Door
Shock Wave
Isolator
Vehicle and Propulsion system are totally integrated

18. RBCC Modes of Operation
Air-Augmented
Ejector Mode
Mach = 0—3
AIR
AIR
Ramjet Mode
M = 3—6
M <1
GREEN ARROWS: FUEL INJECTION
AIR
M >1
Scramjet Mode
M = 6—10
Inlet Closed
Rocket Mode
M > 10
Each mode is sub-optimized in its operating range

19. RBCC-TBCC

20. Pulsed Detonation Engines
Pulse Detonation Engine
Operating Concept
Detonation is initiated 2
Detonation wave moves
through fuel-air mixture 3 4
Resulting high pressure gas
fills detonation chamber 1
Fuel is mixed with air
Detonation wave exits engine
Air drawn in by reduced pressure 5
Typical:
40 cycles/sec

21. Re-Entry

22. Re-Entry: Meteors
Element
Color
Sodium
Iron
Magnesium
Calcium
Silicon