1. Liquid & Solid Propulsion Overview
Dr. Richard Cohn
Chief, Liquid Engines Branch
Propulsion Directorate
Air Force Research Laboratory
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2. Space and Missile R&D Building Block Process
6.1
6.2
6.3
As part of the IHPTET “GOTChA” process, technology is developed and demonstrated in a building block approach, which also serves to reduce risk.
First, components such as fans, compressors, combustors, controls, and turbines are developed and brought to a technology readiness level of The high pressure or “core” engine components are integrated into an Advanced Turbine Engine Gas Generator (ATEGG) for their initial demonstration in an engine environment (TRL - 5+ ). Then low pressure components and control systems are added and the engine tested in the Joint Technology Demonstrator engine (JTDE) program (TRL - 6). Here, in addition to demonstrating the feasibility to the low pressure components, the interactions between the high and low pressure spools are assessed.
Following successful engine demonstration, IHPTET technologies are then considered sufficiently mature for low risk transition to an Engineering and Manufacturing Development (EMD) program, leading to eventual production.
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3. Integrated High Payoff Rocket Propulsion Technology (IHPRPT)
Joint government and industry effort focused on developing affordable technologies for revolutionary, reusable and/or rapid response military global reach capability, sustainable strategic missiles, long life or increased maneuverability spacecraft capability and high performance tactical missile capability
Chart #3: What is IHPTET?
The Integrated High Performance Turbine Engine Technology Program (pronounced ip’tet) is exactly what it says it is. It’s a technology program focused on providing more affordable(1), more robust(2), higher performance(3) turbine engines across the entire spectrum of military aviation...
From missiles to transports, helicopters to bombers, fighters to tanks, IHPTET is providing what the users want and need(4):
Users need weapon system superiority in all theaters!
Users want dependability and affordability!
IHPTET is doing just that by embodying virtually all DoD S&T investments related to turbine engine technology development towards one common set of goals ....
1 “Affordable” meaning lower cost relative to development, production, and maintenance
2 “Robust” meaning tolerance to variations from design to manufacturing to field usage – improved engine readiness
3 “Higher Performance” meaning improved thrust-to-weight ratio & fuel burn yielding smaller a/c with same capability or same size a/c with increased capability
4 “Wants & Needs” can be summarized by looking at the ratio of (payload x speed)/cost
ELVs
ICBMs
Micro-Satellites
SLBMs
Satellites
High Energy
Upper Stages
SMV/SOV
Ground/Surface
Launched Missiles
Air-to-Air Missiles
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4. IHPRPT Goals Boost and Orbit Transfer Propulsion Near Mid Far
Improve ISP (sec)
Improve Thrust to Weight (Liquids) 30% 60% 100%
Improve Mass Fraction (Solids) 15% 25% 35%
Mean Time Between Removal (Missions)
Reduce Stage Failure Rate 25% 50% 75%
Reduce Hardware Costs 15% 25% 35%
Reduce Support Costs 15% 25% 35%
Spacecraft Propulsion
Improve Itot/Mass (wet) (Electrostatic/Electromagnetic) 20%/200% 35%/500% 75%/1250%
Improve Isp (Bipropellant/Solar Thermal) 5%/10% 10%/15% 20%/20%
Improve Density-Isp (Monopropellant) 30% 50% 70%
Improve Mass Fraction (Solar Thermal) 15% 25% 35%
Tactical Propulsion
Improve Delivered Energy 3% 7% 15%
Improve Mass Fraction (Without TVC/Throttling) 2% 5% 10%
Improve Mass Fraction (With TVC/Throttling) 10% 20% 30%
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5. Solid Motor Technology development for the warfighter
Increase performance at reduced cost
Improve tools to reduce life cycle cost and enable increased capability
Aging and Surveillance
Sustain industry technology development
Technology development is critical to sustaining strategic system capability and affordability
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6. Solid Performance Technology
Inert Components
High strength composite case
Low erosion / non-eroding nozzle
Low erosion insulation
Energetic components
Increased energy/low sensitivity ingredients
High performance 1.3HC propellant
Technology demonstration
Delivered performance of integrated components
Demonstration of IHPRPT goal compliance
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7. M&S Technology Performance Thermostructual
Multi-phase computational fluid dynamics
Combustion of metallized propellants
Ignition transient including erosive burning
Thermostructual
Multi-phase heat transfer
Material ablation, erosion, and burnback geometry
Fluid Thermal Structural Interaction
Coupled solutions
Model verification and validation
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8. Aging and Surveillance Technology
Service life prediction technology
Assessment of critical defects
Propellant damage model development
Environmental effects on material life
Integrated motor life management
Integrated sensor/data/analysis system
Smart sensor technology
Long term data warehousing
Automated non-destructive evaluation
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9. AFRL Edwards Rocket Site: Liquid Rocket Technology Development
RS 68- A/B
ARES
Military Space
Plane & SOV
On-Demand Launch
(RBS)
Air Force Programs
Air Force Proposed
Other Programs
DC-X
Space Vector 1
Centaur Upper Stage
X-33
J2X
Concept
Engine
AFRL HC Boost
X-15
AFRL IPD
SSME
Space
Shuttle
Main: -
Transition:
Sanger-In June 1935 and February 1936, Dr. Eugen Sänger published articles in the Austrian aviation publication Flug on rocket-powered aircraft. This led to his being asked by the German High Command to build a secret aerospace research institute in Trauen to research and build his "Silverbird", a manned, winged vehicle that could reach orbit. Dr. Sänger had been working on this concept for several years, and in fact he had began developing liquid-fuel rocket engines. From 1930 to 1935, he had perfected (through countless static tests) a 'regeneratively cooled' liquid-fueled rocket engine that was cooled by its own fuel, which circulated around the combustion chamber. This engine produced an astounding 3048 meters/second (10000 feet/second) exhaust velocity, as compared to the later V-2 rocket's 2000 meters/second (6560 feet/second). Dr. Sänger, along with his staff, continued work at Trauen on the "Silverbird" under the Amerika Bomber program
X-1 A-E: The Bell X-1, originally XS-1 was the first aircraft to exceed the speed of sound in controlled, level flight. It was the first of the so called X-planes, a series of aircraft designated for testing of new technologies and usually kept highly secret. Rocket plane
X-2 was an AAF/ Bell project that flew three supersonic flight research aircraft, powered by liquid rockets. Originally designated XS-2. The X-2 was the first swept-wing X rocketplane. It exceeded Mach 3, but in the course of doing so uncovered the supersonic aircraft problem of inertial coupling. On its last flight the aircraft crashed and the pilot was killed.
X-15: As with many of the X-aircraft, the X-15 was designed to be carried aloft under the wing of a B-52. The fuselage was long and cylindrical, with fairings towards the rear giving it a flattened look, and it had thick wedge-shaped dorsal and ventral fins. The retractable landing gear consisted of a nose wheel and two skids — to provide sufficient clearance part of the ventral fin had to be jettisoned before landing. The two XLR-11 rocket engines of the initial model X-15A delivered 36 kN (8,000 lbf) of thrust; the "real" engine that came later was a single XLR-99 that delivered 254 kN (57,000 lbf) at sea level, and 311 kN (70,000 lbf) at peak altitude.
The Dyna-Soar was America's first manned spacecraft which actually reached the hardware stage. Conceived in 1957 as a logical next step after the X-15 rocket plane, the Dyna-Soar (originally designated X-20) was based on Eugen Sanger's WWII-era "Silver Bird" concept of a bomber which could skip around the globe on the upper atmosphere.
The USAF saw the Dyna-Soar as their first step into the military use of outer space and planned numerous versions of the ship, including satellite inspection and electronic and photographic intelligence gathering (shown here). Later versions were also planned as mini-space stations and "orbital bombers" which could carry "stand-off" nuclear weapons into orbit.
X-30, National Aerospace Plane: Originally conceived as a feasibility study for a single-stage-to-orbit (SSTO) airplane which could take off and land horizontally
DC-X: The McDonnell Douglas DC-X, better known as the Delta Clipper or Delta Clipper Experimental, was an unmanned prototype of a reusable single stage to orbit launch vehicle developed in conjunction with NASA and the DOD SDIO from 1991 to The DC-XA reached a maximum altitude of 3140 m and set a world record of a 26-hour turnaround between launches of a reusable rocket
MSP X-40:
X-33: The X-33 is a test bed for the VentureStar project, a manned, single stage, multiple use, heavy lift spacecraft. The X-33 is an approximate 1/3 scale of the 127' long VentureStar. The X-33 is being developed at the famed Lockheed "Skunkworks", and is being outfitted with an "aerospike" engine, composite components and other state-of-the art advances. This project was cancelled  by NASA in March, 2001.
The XLR-99 rocket engine was built by the Reaction Motors Division of Thiokol Chemical Corporation specifically to power the North American X-15 rocket research aircraft. It used anhydrous ammonia and liquid oxygen as propellants. The XLR-99 was, at one time, listed in the Guinness Book of World Records as the most powerful aircraft engine ever used. Its thrust rating of 57,850 pounds was equal to 600,000 horsepower.
Work on experimental engine XLR-129 began. This research provided the basis for NASA's Space Shuttle Main Engine. The XLR-129 work was conducted between the years of 1965 and Air Force influence in the design of this engine was also very significant. The Air Force during the mid-sixties had sponsored the Pratt and Whitney development of the XLR-129 reusable rocket engine. The engine used a closed combustion cycle that produced vacuum specific impulses of 444 seconds.
The XLR-129 contributed substantially to the staged combustion technology, which was provided to NASA and made available to all potential engine contractors. Rocket-dyne’s closed-cycle engine emerged the winner of the engine competition.
XRS-2200
AFRL Thrust
Cell Program
RL-10
AFRL XLR-129
AFRL Aerospike Tech
CL-400 Suntan
AFRL XLR-99
Four Decades of Leadership in Rocket Engine Technology
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10. Responsive Space Access Time Phased Plans
Increasing Reusability
Rapid turn 48 hrs
3X lower ops cost
Vehicle reliability
All Wx availability
High Sortie Airframe
High Sortie Propulsion & Systems
Rapid turn 24 hrs
10X lower ops cost
Vehicle reliability
All Wx availability
2X Sortie Airframe
2.5X Sortie Propulsion & Systems
Rapid turn 4 hrs
100X lower ops cost
Vehicle reliability
All Wx availability
4X Sortie Airframe
5X Sortie Propulsion & Systems
BASELINE
EELV, Shuttle,
Aircraft Ops
Near Term
Mid Term
Far Term
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11. Liquid Rocket Drive towards Modeling and Simulation
Rocket Engine Development Programs
IPD (LOx/LH2 Booster)
USET (LOx/LH2 Upper Stage)
Hydrocarbon Boost (LOx/RP-2 Booster)
3GRB (LOx/LCH4 Booster)
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12. Drive Towards Model Driven Development
There is a need to improve year old modeling, simulation, & analysis (MS&A) tools
Existing tools old and empirically based and require hundreds of tests
Industry losing grey beards and thus design and analysis capability
Could not handle new technologies like hydrostatic bearings
Current and future computational capabilities allow use of physics-based tools to supplement testing
Testing drives the cost of rocket programs
Necessary
Need to be smart
Test Driven Development (TDD)
Model Driven Development (MDD)
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13. Integrated Powerhead Demo (IPD)
Joint program between AF, NASA, and Industry
Supports sortie-like launch for Operationally Responsive Space (ORS)
Payoffs:
200 Mission Life (20X improvement)
100 MTBR
First known full scale demonstration of Full Flow Staged Combustion Cycle in the World!
IPD Ground Demonstrator Engine installed in E1 Complex Cell 1
IPD Ground Engine: E1 Test Stand NASA SSC, Test 013TA: Standard Start to 80%PL, 87%PL w/ Short Hold; Test Profile RA, November 10th, 2005
IPD Ground Engine: E1 Test Stand NASA SSC, Test 014TA: Standard Start to 85%PL, (Actual 89%PL) w/ Steady State; Test Profile SA, December 15th, 2005
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14. - Range of Thrust - Range of Propellants - Range of Engine Cycles
USET Objective
Objective: Develop and demonstrate the next generation Model Driven Design (MDD) tools on an upper stage engine component
Selected Turbopump
Approach:
Link commercial design tools with rocket specific empirical data, rocket specific material & propellant libraries, and user defined functions
Replace targeted legacy design tools with physics based tools
Enable Multi-Disciplinary Models, Time Accurate Solutions & Interconnected Models
Reduced design time, more design iterations
Higher fidelity analysis earlier in process
Multi-disciplinary optimization
Use Tools to design validation turbopump assembly
Validation: provide sealed envelope predictions to compare with test data
Models & design tools applicable to other Liquid Boost & OTV Applications
- Range of Thrust - Range of Propellants - Range of Engine Cycles
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15. Developing LOx/RP staged combustion Technology
Hydrocarbon Boost
Developing LOx/RP staged combustion Technology
Component Testing
Subscale / Rig Testing
TRL 5
TRL 4
Vision Engine
TRL 3
Component TRL – Red
System TRL - Purple
Mondalloy – High Strength
Ox-Compatible Material
TRL 5
Integrated Demo Testing
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16. 3GRB Advancement of the state of the art
Innovative cycles/ component technologies
Pursue IHPRPT Hydrocarbon Boost Phase III and Operability Goals
Fuel Choice
Rocket Grade Methane MIL-PRF is the baseline fuel
Methane has high potential as fuel for booster stage rocket engines
Database and experience on pump fed methane engines is lacking in US
AFRL to leverage existing pressure fed activities (NASA)
Develop rocket engine components
Component and/or breadboard validation in laboratory environment
No integrated demonstartion
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17. Conclusions
AFRL/RZS is developing new technology in liquid and solid propulsion
Mix of Tech Push and Mission Pull
Primary customer is SMC
Focused efforts examining Cryo-Boost, HC Boost, and Upper Stage Rocket Propulsion
Aggressive goals lead to unique vision engines
Tool development is crucial
Developing the critical demonstration programs as well as the key underlying technologies
Mondalloy
Other parts of AFRL working air-breathing concepts
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18. Comments on Roadmap
Reads like a technology review of propulsion concepts
All work seems to be nearly in parallel
Many technologies have been worked in the past
Fundamental changes that make them more effective?
Combination of new technology and “engineering” development
Some are being worked
For more details on current activities, recommend a non-public release environment
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19. PWR Vision Engine Expander-Heat Exchanger Cycle (Ex-Hex)
HEX reduces system pressures
Enables higher Pressure Ratio turbine
Reduces heat required to run cycle
Significantly reduces Turbopump power
Ex-Hex Eliminates Preburner
No moisture / contaminates
Eliminates drying / flushing
Significantly reduces Ground-Ops
Low CH4 Hot Gas Temp
Reduced hot gas system complexity
Benign fluid environment
Improved turbine drive system life
Lower Engine pressures
Existing test facility infrastructure
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20. WASK Vision Engine Staged Combustion Cycle Modular engine design
Low Preburner Gas Temperature Assures Long Life
Modular engine design
Small TCAs Lower Development and Test Costs
Altitude compensating nozzle
Innovative TPA
Eliminated boost pumps
Single shaft
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