Optimization of a Reusable Rocket-Powered, VTVL Launch System: A Case Study of the Falcon 9-R

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1 Optimization of a Reusable Rocket-Powered, VTVL Launch System: A Case Study of the Falcon 9-R 04 August 2014 John E. Bradford, Ph.D. President, Principal Engineer [email protected] Brad St. Germain, Ph.D. Director, Advanced Concepts Group [email protected] Kevin Feld Sr. Aerospace Engineer [email protected]

2 Case Study SpaceWorks was interested in examining the performance of the SpaceX Falcon 9-R system that is currently under development as a test case for the VTVL simulation System closure simulation created in PHX ModelCenter allowed us to quickly reverse engineer the baseline Falcon 9 system and anchor the models to various pieces of public information Gross mass and propellant loads Engine performance specifications Vehicle dimensions and fairing geometry Mission launch profile (times, altitudes, velocities) Statements made by SpaceX employees Anticipate that as additional details on the F-9R performance are released, the model can be further validated and/or calibrated Using the reference closure model, we were then able to assess the impact of reusability on the system and explore various sensitivities 2

3 Reference Concept Non-proprietary Falcon 9 v1.1 system Public data sources and engineering models calibrated for: Geometry Propellant loads Propulsion Aerodynamics Trajectory Fairing Assumed flight constraints common for expendable launch systems Parameter Gross Liftoff Weight Upperstage Gross Weight Total Height Diameter Value 1,115,200 lbm 246,150 lbm 224 feet 12 feet Liftoff T/W 1.2 Reported Payload to LEO 28,990 lbm Image Credit: SpaceX 3

4 VTVL Assessment Examined downrange booster recovery as well as RTLS option Fixed vehicle size and mass, per the reference concept Booster stage mass model includes landing system/legs Recovery/Landing Requirements: Vertical orientation (gamma -90 deg) at touchdown touchdown < 20.0 fps Single-engine operation for terminal maneuver 3 engines operable for any initial boostback burn Max. heat rate constraint of 15 BTU/ft2-s (assumed) Optimization: Maximum upperstage payload mass that can be delivered to LEO for either the expendable booster case, booster with RTLS recovery, or booster with downrange landing 4

5 VTVL Concept Simulation Model Created a multi-disciplinary simulation using Phoenix Integration s ModelCenter engineering environment 5

6 Results : FlightSight Images Downrange Landing Booster Parameter Flight Time Final Downrange Distance Max Downrange Distance Value 390 sec 156 nmi 156 nmi Mach Staging 7.1 Staging Peak Altitude 201,500 feet 271,500 feet RTLS Maneuver Booster Parameter Flight Time Final Downrange Distance Max Downrange Distance Value 480 sec ~0 nmi 57 nmi Mach Staging 6.0 Staging Peak Altitude 187,000 feet 423,500 feet 6

7 Results : Trajectory Details Altitude vs. Time Mach Number vs. Time 7

8 Results : Trajectory Details(2) Downrange vs. Time Thrust vs. Time 8

9 Results: Performance Summary Booster Parameter Expendable Downrange RTLS Landing Propellant Used 0 lbm 44,350 lbm 84,680 lbm Recovery Propellant (% Booster Total Prop) 0.0 % 5.5 % 10.5 % Staging Mach Number Videal Post-Staging 0 fps 5,400 fps 8,900 fps 9

10 Trade Study Examined impact of removing max. heat rate constraint for recovery trajectories RTLS trajectory was not impacted (inactive constraint), but the downrange case was impacted significantly 10

11 Conclusions 11

12 Summary SpaceWorks has developed a system closure and optimization model for VTVL concepts Simulation capability was tested using performance data for the SpaceX Falcon 9 v1.1 PHX ModelCenter implementation enabled rapid trade studies and system sensitivity analyses For case study, the performance impacts of two different first stage propulsive recovery options (downrange landing and RTLS) were evaluated and compared to non-recoverable options Downrange propulsive landing results in a ~20% drop in payload performance compared to expendable booster mission; RTLS results in a ~40% drop in payload compared to expendable (no recovery) approach Regarding the cost savings due to reusability, gains must outweigh performance reductions Expendable upperstage, estimated at ~$20M, establishes floor for $/lbm-payload Must also include booster propellant and refurbishment costs (at a minimum) Cost savings may not be as significant as some claim, but appears to still be a net gain Progress is being made, but we need to continue push for full reusability on these systems 12

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