Comparison of Return to Launch Site Options for a Reusable Booster Stage

Transcription

1 Comparison of Return to Launch Site Options for a Reusable Booster Stage Barry Mark Hellman Space System Design Lab (SSDL) School of Aerospace Engineering USAF ASC/XRE barry.hellman@wpafb.af.mil Advisor Dr. John R. Olds In Partial Fulfillment of the Requirements for the Degree of Master of Science in Aerospace Engineering p. 1

2 Presentation Overview Motivation of Study Historical Background Study Conclusions Technical Approach Staging Point Comparison Results of Trajectory and Vehicle Sizing Future Plans p. 2

3 Study Motivation Current desire to develop reusable booster Study uses expendable upper stage (ARES) Booster recovery options Return to Launch Site (RTLS) Land at a site downrange RTLS Requirements Velocity direction must be reversed Staging occurs in near vacuum Enough margin to land safely 15,000 ft over launch site (KSC) p. 3

4 Booster RTLS Methods Glideback Re-enter at high alpha, aerodynamic turn, and glide to launch site Completely unpowered after staging Flyback Re-enter at high alpha, aerodynamic turn Glide to subsonic cruising altitude Use airbreathing engine to cruise back to launch site Currently felt to be the proper solution Boostback Pitch booster around after staging Fire ascent engine until booster s velocity vector points towards launch site Unpowered re-entry and glide to launch site Compare methods based on gross and dry weight 15,000 lb payload direct insertion into 100 nmi circular Boostback Shows Significant Potential p. 4

5 Historical Look at Reusable Boosters Glideback Future Space Transportation System (early 80 s) Flyback Liquid Flyback Space Shuttle Boosters (80 s 90 s) Tokyo University Flyback vs. Glideback Study ( 03) Boostback Kistler K-1 (late 90 s - present ) Which is Best for a Hybrid System? p. 5

6 Technical Approach Baseline Configuration (Hybrid) LOX Tank RP Tank LOX/RP Engines 110 ft 28 ft LOX Tank RP Tank 165 ft p. 6

7 Technical Approach Branching Trajectories Three branches of flight Ascent Orbital RTLS Requires an MDO method handle growth of booster due to RTLS Orbital Branch Ascent Branch RTLS Branch p. 7

8 Technical Approach Design Structure Matrix Configuration Aerodynamics (APAS) Rocket Propulsion (REDTOP-2) Airbreathing Propulsion (PARA) (If Needed) Ascent Trajectory (3D POST) RTLS Trajectory (3D POST) Avionics Weights (SESAW) Weights & Sizing (EXCEL and Solver) p. 8

9 250 Trajectories Minimum Dry Mass Vehicles 200 Return to Launch Site Altitude (nmi) Ascent Glideback (Stage at 3.2) Flyback (Stage 6.4) Boostback (Stage at 5.2) Downrange (nmi) p. 9

10 RTLS Booster Required MRs 3.5 Ascent Required Mass Ratio Minimum Dry Weight Points RTLS Mass MR = Mass initial final Flyback RTLS MR Boostback RTLS MR Flyback Ascent MR Boostback Ascent MR Staging Mach p. 10

11 Gross Mass Comparison 1,000,000 Points are Lowest Dry Mass Design Total Gross Weight (lbm) 950, , , % 6.02% Flyback Glideback Boostback Minimum Dry Weight Points 800, Staging Mach Gross Mass is not a Direct Indicator of Cost p. 11

12 Dry Mass Comparison 105, ,000 Total Dry Weight (lbm) 95,000 90,000 85, % Flyback Glideback Boostback 80,000 75, % Staging Mach Minimum Dry Weight Points Unfortunately Dry Mass is not a Direct Indicator of Hybrid System Cost A Cost Trade will be Needed p. 12

13 Optimal Staging Points Parameters from Optimal Staging Point Glideback Flyback (Lowest Dry Mass) Boostback (Lowest Dry Mass) Staging Ideal V (ft/sec) 7,248 11,200 10,200 Staging Mach Number Staging Altitude (ft) 106, , ,224 Staging FPA (deg) Max Re-Entry Mach Total Gross Mass (lbm) 822, , ,300 Upper Stage Dry Weight (lbm) 20,100 17,200 18,600 Total Dry Mass (lbm) 78,100 95,800 81,000 Booster Length (ft) Upper Stage Length (ft) RTLS Time (sec) Too Close to Call: Need Cost Study p. 13

14 Results Glideback Lowest dry and gross mass Low Complexity Requires No TPS (Re-entry Mach 1.8) Probably not lowest cost due to large expendable upper stage Flyback Very low RTLS propellant required Flyback requires turbofan and installation hardware Highest dry mass Powered landing and go-around capability Long Return TOF ~ 78 min Requires Significant TPS (Re-entry Mach 6.9) Boostback Requires Minimal TPS (Re-entry Mach 2.7) Short Return TOF ~ 13 Boostback requires more return propellant Unpowered landing Boostback Deserves Consideration Cost Study Needed p. 14

15 Future Work Need to pick staging point based on cost for hybrid system Booster cost is amortized over flights New upper stage for each launch Staging concerns Rocket relight vs. continuous burn Separation More in depth look at TPS requirements Compare maintenance requirements between Boostback and Flyback p. 15

16 Backup p. 16

17 Previously Studied RTLS Boosters Future Space Transportation System (Glideback) Space Shuttle Replacement (80 s Design) Stage at Mach 3 Liquid Flyback Space Shuttle Boosters (Flyback) Stage at Mach 5.2 at 163,000 ft Coast to apogee of 270,000 ft Cruise at 18,500 ft and Mach 0.48 p. 17

18 Previously Studied RTLS Boosters Kistler K-1 (Boostback) Mach kft Parachute Landing 12 min after liftoff p. 18

19 Technical Approach Contributing Analyses Aerodynamics APAS Airbreathing Propulsion Isp ~ 3600 sec SFC ~ 1/hr Rocket Propulsion Spaceworks Engineering Inc. s REDTOP 2 LOX/RP, Gas-Generator, 2500 psi Weights & Sizing Booster weights based on MER from Dr. Ted Talay NASA LARC Trajectory POST 3D p. 19

20 Glideback Final Altitude 50,000 45,000 Final Altitude Over Launch Site (ft) 40,000 35,000 30,000 25,000 20,000 15,000 10,000 5, Staging Mach Number p. 20

21 Ground Track p. 21

22 Boostback Booster and Upper 100,000 Total Dry Weight (lbm) 90,000 80,000 70,000 60,000 50,000 40,000 30,000 Booster Upper Total 20,000 10, Staging Mach Number p. 22