Concept Assessment of a Hydrocarbon Fueled RBCC-Powered Military Space Plane Presentation to 54 th JANNAF Propulsion Meeting/5 th MSS/3 rd LPS May 14-17, 2007, Denver, CO John E. Bradford, Ph.D. President SpaceWorks Engineering, Inc. (SEI) john.bradford@sei.aero 1+770.379.8007 John R. Olds, Ph.D., P.E. Principal Engineer/CEO SpaceWorks Engineering, Inc. (SEI) john.olds@sei.aero 1+770.379.8002 Jon G. Wallace Senior Project Engineer SpaceWorks Engineering, Inc. (SEI) jon.wallace@sei.aero 1+770.379.8008 1
C O N T E N T S I II III IV V Program Introduction Analysis Tools and Modeling Sentinel Concept Trade Studies Conclusions 2
I I N T R O D U C T I O N 3
TITLE SPONSOR TIMELINE OBJECTIVES GOALS Innovative Concept Development for RLVs Using Combined-Cycle Propulsion for Military Applications Air Force Research Lab( AFRL) at Wright-Patterson Air Force Base (WPAFB) Phase-1 Start Date: September 17 th, 2003 Phase-2 Start Date: September 17 th, 2004 Contract End Date: July 17 th, 2006 Integrate combined-cycle propulsion systems with new conceptual designs of future military RLVs For all phases, -the design methodologies and tools used for this process are based at the conceptual/preliminary level and will model the full life cycle of the program -a multi-disciplinary performance assessment is used to obtain vehicle closure, subsequently a cost assessment is performed to determine non-recurring, operations, and system acquisition costs Enable propulsion technologists to see effect of CCE technologies on design of a launch system Perform a more realistic analysis of the breadth of the impact of that technology on the cost and operational complexity of the entire system Concurrently, innovative concepts will be developed that showcase new capabilities available to the military from such architectures P R O J E C T O V E R V I E W 4
FIVE ADVANCED TSTO MILITARY SPACE VEHICLES VEHICLE SYSTEM CONFIGURATION PROPULSION PAYLOAD PROPELLANTS Quicksat MSP Hybrid HTHL A/B (TBCC+DMSJ) + Rockets 13klbs SMV, LEO JP-7 & H2O2 Sentinel MSP Hybrid VTHL A/B (RBCC) + Rockets 13klbs SMV, LEO JP-7 & LOX ARES Hybrid-OS Hybrid VTHL All-Rocket 15klbs cargo, LEO RP-1 & LOX ARES Spiral-1 Fully- Reusable VTHL A/B (Ram/Scram) + Rockets 10klbs cargo, LEO RP-1 & LOX, LH2 & LOX ARES Spiral-2 Hybrid HTHL A/B (TBCC+DMSJ) + Rockets 15klbs cargo, LEO JP-7 & H2O2 RP-1 & LOX S P A C E 5
II A N A L Y S I S T O O L S & M O D E L I N G 6
PHOENIX INTEGRATION MODELCENTER ENGINEERING ENVIRONMENT www.phoenix-int.com C L O S U R E 7
DISCIPLINE Industry Common Tools TOOLS In-House, SEI-Developed Tools CAD & Packaging Solid Edge IDEAS (SDRC) - Aerodynamics APAS (UDP and S/HABP) NASCART-GT (Georgia Tech) - Propulsion SRGULL (NASA LaRC) REDTOP, REDTOP-2 (Liquid Rockets) PARADIGM (IRS Cycle Analysis) Trajectory Optimization POST-2 (NASA LaRC) Flyback-Sim Vehicle Performance Aeroheating / TPS S/HABP (NASA) TPS-X Database (NASA ARC) Sentry Weights & Sizing - Parametric MERs, historical databases Excel-based sizing models Subsystems - SESAW (avionics) Operations Architecture Assessment Tool - Enhanced (AATE, NASA KSC) - Safety /Reliability Economics and Cost - NAFCOM (NASA/SAIC) GT-Safety II Cost and Business Analysis Module (CABAM) Economic Closure Facilities and Ground Support Equipment Systems Engineering - ModelCenter (Phoenix Int.) Analysis Server (Phoenix Int.) Facility, Ground Support Equipment, and Operations Assessment (FGOA) Tool OptWorks (Pi Blue Software) ProbWorks (Pi Blue Software) Collaborative Design and Optimization E N G I N E E R I N G 8
III S E N T I N E L 9
- Two-Stage-To-Orbit (TSTO) Military Space Plane (MSP) concept - Target IOC 2020-2025 - Booster first stage (SOV) referred to as the Sentinel - Configuration enables Vertical Takeoff and Horizontal Landing (VTHL) - Fully reusable booster with expendable upperstage - Primary mission to deliver 13K lb. SMV to Low-Earth-Orbit (LEO) - Booster uses hydrocarbon (JP-7) fuel for RBCC main engines - JP-7 and LOX propellants for main propulsion rocket systems on both stages - Capable of fully autonomous, unpiloted flight - Booster supports powered, supersonic flyback to launch site (RTLS) O V E R V I E W 10
S E N T I N E L M S P 11
SPACE MANEUVERING VEHICLE A reusable vehicle capable of remaining on-orbit for extended periods of time Supports rapid micro-satellite replenishment, on-orbit servicing, ground surveillance, and intelligence gathering Currently envisioned as a winged-body airframe, weighing approximately 13Klbs, a nose-to-tail length of 27.5 feet, and wingspan of 15 feet Features a small, kerosene and H 2 O 2 liquid rocket engine (AR2-3) for on-orbit maneuvering P A Y L O A D 12
M I S S I O N 13
51.3 ft 143.3 ft Space Maneuver Vehicle (SMV) Gross Weight system (lbs): 756,545 Dry Weight Sentinel (lbs): 158,060 Dry Weight Upperstage (lbs): 4,250 Mass Ratio Sentinel: 2.638 Mixture Ratio Sentinel: 1.185 Length (feet) 143.3 Booster Payload (lbs): 78,735 Space Maneuver Vehicle (lbs): 13,090 B A S E L I N E 14
(4) RBCC engines using Independent Ramjet Stream (IRS) cycle ACC TPS leading edges (nose, cowl, wings, and tails) Gr-Ep Airframe primary and secondary structure Ti-Al hot-structure (wings and tails) Cylindrical, non-integral Gr-Ep fuel and oxidizer tanks CRI TPS blankets (fuselage, windward) AFRSI blankets (leeward fuselage) EHA s (electro-hydraulic actuators) for control surfaces No OMS engine requirement Booster Specific Cylindrical, non-integral Al propellant tanks Single JP-7/LOX rocket engine AFRSI TPS blankets over unshielded upper surface MPS engine used as OMS engine for deorbit burn OMS deorbit delta-v of 100 ft/s Upperstage Specific Pressure-fed, bipropellant RCS Advanced avionics for autonomous flight capability Extensive Integrated Vehicle Health Monitoring (IVHM) systems Entire System T E C H N O L O G I E S 15
KEY PERFORMANCE VALUES: PARAMETER Initial Weight (lbs) Weights at Staging (Booster/Upperstage) (lbs) Upperstage Final Weight on Orbit (lbs) Downrange Distance at Staging (nmi) Delta-V Flight (fps) Delta-V Total (fps) ISTAR (Booster/Upperstage/System) (s) VALUE 756,545 207,886 / 78,735 19,080 335 24,496 31,580 288.4 / 339.8 / 319.1 KEY TRAJECTORY EVENTS SUMMARY EVENT TIME (s) Liftoff 0 Mach 1.0 70 End of IRS-mode, Mach 3.5 120 Total Delta-V Contributions End of DMSJ-mode Operation, Mach 8.0 266 Gravity 11.9 % Thrust Vectoring 1.0 % Drag 9.5 % Flight 77.6 % Staging Maneuver (9,000 fps) SMV Release at 70 by 197 nmi. orbit 341 575 Total delta-v = 31,580 ft/s P E R F O R M A N C E 16
VEHICLE HARDWARE SYSTEM COMPONENT WEIGHT (lbs) COMPONENT WEIGHT (lbs) Wings and Tails (with carry through structure) 25,810 Dry Weight 158,060 Airframe Structure (bulkheads, tanks, etc.) 34,605 Payload (Upperstage with SMV) 79,330 Thermal Protection 14,785 Residual Propellants 1,075 Landing Gear Main Propulsion 13,090 Reserve Propellants LANDED WEIGHT 3,860 242,325 RBCC (installed) 40,285 Flyback Propellants 26,195 ACS Propulsion 770 ENTRY WEIGHT 268,520 Subsystems (power, EHAs, EC&D, avionics, ECCLS) 8,100 ACS Propellants 3,920 Programmatic Margin (15%) 20,615 Unusable Propellants 14,370 DRY WEIGHT 158,060 INSERTION WEIGHT 286,810 Ascent Propellants JP-7 Fuel 225,965 LOX Oxidizer 243,770 GROSS WEIGHT 756,545 Startup Losses 4,700 *Component categories represent rolled up totals from Level-3 WBS W E I G H T S 17
VEHICLE HARDWARE SYSTEM COMPONENT WEIGHT (lbs) COMPONENT WEIGHT (lbs) Wings and Tails (with carry through structure) 0.0 Dry Weight 4,250 Airframe Structure (bulkheads, tanks, etc.) 1,290 Payload (SMV) 13,090 Thermal Protection 275 Residual Propellants 65 Landing Gear Main Propulsion 0.0 Reserve Propellants ENTRY WEIGHT 475 17,880 Rocket 1,550 ACS Propellants 595 ACS Propulsion 135 Unusable Propellants 610 Subsystems (power, EHAs, EC&D, avionics, ECCLS) 615 INSERTION WEIGHT 19,085 Programmatic Margin (10%) 385 Ascent Propellants DRY WEIGHT 4,250 JP-7 Fuel 16,085 LOX Oxidizer 43,565 GROSS WEIGHT 78,735 Startup Losses 595 *Component categories represent rolled up totals from Level-3 WBS W E I G H T S 18
4 flowpaths each with single rocket/fuel injector powerpack Sized to provide ~1.25 liftoff thrust-to-weight Baseline engine T/W: 27:1 uninstalled and 23.5:1 installed Cowl leading edge to trailing edge length of 37.9 feet Rocket Powerpack: Propellants: LOX/JP-7 Mixture Ratio: 2.7 Chamber Pressure: 2,500 psi Expansion Ratio: 10:1 Rocket is always at full-power INDEPENDENT RAMJET STREAM CYCLE MACH NUMBER ALTITUDE (FT) THRUST (LBS) ISP (S) 0.0 0.0 236,420 330.6 0.5 0.0 233,760 323.4 1.0 20,000 228,900 313.3 2.0 40,000 236,970 323.1 3.0 60,000 342,480 457.3 3.5 60,000 367,320 464.9 *Representative performance values, not at actual flight conditions Thrust values correspond to reference vehicle of 135 ft I R S R B C C 19
4 Flowpaths for RBCC DMSJ-mode operation Three-ramp, 2-D external compression system Initial 5 o ramp from nose Transitions to 9 o ramp Final 12 o turn to engine inlet Shock-On-Lip (SOL) condition at Mach 8 Variable geometry inlet with thermal choke in combustor Fixed geometry cowl at 0 o incidence with waterline Performance estimates generated with SRGULL 0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 Minimum Contraction (takeoff to Mach 4) 0.00 200.00 400.00 600.00 800.00 1000.00 1200.00 1400.00 0.00 20.00 40.00 60.00 80.00 100.00 120.00 140.00 160.00 Maximum Contraction (Mach >6) H I G H - S P E E D 20
2,500 2,250 Initiate Pullup Maneuver @ Mach 8 450,000 405,000 2,000 360,000 1,750 315,000 Dynamic Pressure (psf) 1,500 1,250 1,000 750 270,000 225,000 180,000 135,000 Altitude (ft) 500 90,000 250 Dynamic Pressure Altitude 45,000 0 0 50 100 150 200 250 300 350 400 450 500 550 600 0 Time (seconds) T R A J E C T O R Y - 1 21
30.0 27.5 25.0 Mach Number Altitude 450,000 412,500 375,000 22.5 337,500 20.0 300,000 Mach Number 17.5 15.0 12.5 262,500 225,000 187,500 Altitude (ft) 10.0 150,000 7.5 Mach 8.0 112,500 5.0 75,000 2.5 37,500 0.0 0 50 100 150 200 250 300 350 400 450 500 550 600 0 Time (seconds) T R A J E C T O R Y - 2 22
0.07 0.06 0.05 APAS 0.0 deg NASCART-GT 0.0 deg APAS 5.0 deg NASCART-GT 5.0 deg Cd 0.04 0.03 0.02 0.01 0 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 Mach Number Mach Number S/HABP ANALYSIS GRID A E R O 23
Mach Number Contours 7.0 5.5 4.0 2.5 1.0 Surface Normalized Pressure 6.5 3.25 Mach Number Alpha 0.1 C 24 F D :5 : 5o
- Results from SEI s Sentry code - 1-D transient thermal analysis - Convective heat rate data supplied from S/HABP - Material property data from NASA Ames TPS-X database - Analysis grid consisted of 2,188 nodes - Avg. TPS material unit weight for vehicle 1.23 psf (all surfaces) - Fuselage leading edge maximum temperature of 2,980 R - Wing/Tails/Verticals leading edges at 3,300 R Component - Fuselage Nose Leading Edge Leeward and Sidewalls Windward Forebody & Aftbody Nozzle Component-Wings Leading Edges Material Stackup ACC CRI and AFRSI Blankets CRI and TUFI AETB-8 Ceramic Tiles Material Stackup ACC Avg. Areal Weight 12.6 psf 0.74 psf 1.28 psf Avg. Areal Weight 12.6 psf Upper and Lower Surfaces CRI Blankets 1.43 psf T H E R M A L 25
IV T R A D E S T U D I E S 26
PARAMETER System GLOW (lbs) Booster Dry Weight (lbs) Upperstage Gross Weight (lbs) Upperstage Dry Weight (lbs) Booster Length (feet) T/W 20:1 927,494 203,965 78,725 4,250 153.9 T/W 27:1 (Nominal) 756,545 158,060 78,735 4,250 143.3 T/W 35:1 665,895 133,510 78,715 4,250 137.0 E N G I N E T / W 27
GLOBAL? - Assessed ability of Sentinel to carry and deploy 4 Hypersonic Technology Vehicles (HTV) - A single HTV weighs 2Klbs and assumed to travel 1,500 nmi. when released at high- Mach - Sentinel upperstage with SMV replaced with conformal tank and carrying rack for HTVs -Vehicle performs similar mission profile up to start of desired cruise condition - Booster then flies lower-q trajectory using propellant load of 61.5Klbs carried externally to extend range - Booster then resumes acceleration profile to achieve nominal staging condition and release point for HTVs at 9Kfps - SEI examined various cruise conditions S T R I K E 28
Fuel Tankage Hypersonic Technology Vehicles Auxiliary Conformal Fuel Tank HTVs (x4) Primary Fuel Tanks (x4) A L T E R N A T E C O N F I G U R A T I O N 29
- Mach 5 cruise condition yielded maximum range! - Without major system modification, the Sentinel does not meet 9,000 nmi range requirements for nearly global strike access for CONUS CRUISE MACH NUMBER 4.0 5.0 6.0 INITIAL WEIGHT (lbs) 420,775 408,830 393,565 CRUISE ALTITUDE (ft) 68,000 76,000 80,000 CRUISE RANGE (nmi) 597 705 642 AVG. L/D 3.06 2.95 2.82 TIME TO RELEASE (minutes) 38.3 37.4 33.8 TOTAL STRIKE RANGE (nmi) 2,432 2,540 2,477 C A P A B I L I T Y 30
V C O N C L U S I O N S 31
SEI utilized Phoenix Integration s ModelCenter to create a highly coupled, multidisciplinary design environment for vehicle closure and optimization Exploration of Combined-Cycle Design Space using Consistent Tools, Processes, and Assumptions Examined TSTO vehicles with a range of propulsion systems, configurations, and propellants ARES evolution could take a path that replaces the booster (i.e. Spiral-2, to improve flexibility of operations) or one that replaces the upper stage (i.e. Spiral-1, to increase reliability and abort options) MSP TBCC and RBCC combined-cycle approaches studied yielded remarkably similar vehicle size and weight results, despite very different low-speed propulsion systems Previously reported on Quicksat TBCC option had much higher Isp up to Mach 3.5 but lacked thrust margin and acceleration capability Sentinel had much lower Isp from RBCC IRS mode up to Mach 3.5, but had ample thrust margin and great acceleration capability Gross Weight (lbs) Dry Weight (lbs) Length (ft) Sentinel RBCC 756,545 158,060 143 Quicksat TBCC 682,000 151,765 118 S U M M A R Y 32
The flyback/rtls requirement for booster is a significant driver on vehicle size Elimination of the flyback requirement resulted in gross weight reduction of ~18% and dry weight reduction of ~14%. SEI does not advocate eliminating RTLS capability due to number of operational advantages it enables Goal is to understand the sensitivity and impact RTLS requirement places on system The RBCC IRS operational mode did not appear to offer any significant thrust or Isp augmentation until flight conditions exceeded Mach 2. Rocket thrusters were shut down from Mach 3.5 to Mach 8 Usefulness of integrating the rockets in the flowpath is questioned Non-integrated propulsion system likely achieve similar performance up to Mach 3.5? DMSJ-mode performance could likely be improved without flowpath interference from rocket Recommend examining alternative RBCC cycles such as SMC or DAB Concept Observations High thrust levels required by main engines to support vertical takeoff result in excessive thrust margin during final pullup maneuver prior to staging Optimal performance solution obtained at 35% throttle Similar issue for SSTO configurations as they approach MECO C O N C L U S I O N S 33