Flight Performance of the Inflatable Reentry Vehicle Experiment 3 10 th International Planetary Probe Workshop June 21, 2013 Robert Dillman 1, John DiNonno 1, Richard Bodkin 1, Valerie Gsell 2, Nathanael Miller 1, Aaron Olds 3, and Walt Bruce 1 1: NASA Langley Research Center, Hampton, VA 2: NASA Wallops Flight Facility, Wallops Island, VA 3: Analytical Mechanics Associates, Hampton, VA

Separate RV & Nose Cone From Brant & Transition 90s, 148km Yo-Yo De-Spin, 80s Brant Burnout, 56.9s Brant Ignition, 23.0s Taurus Separation 21.0s Taurus Burnout, 18.5s Taurus Ignition, 15.0s Talos Burnout, 6.4s Spin Motor Ignition, 0.9s Leaves Rail, 0.5s Talos Ignition, 0s Launch on Black Brant-XI from WFF 940lb payload, El 84deg, Az 155deg Atmospheric Interface, 25Pa (664s, 85km) RV Peak Heat Rate 14.4W/cm2 678s, 50km, Mach 7 (peak Mach 9.8) RV splashdown at 30m/s 1194s (447km downrange) Eject Nose Cone 102s, 176km Apogee 364s, 469km RV Peak Dynamic Pressure 6.0KPa 683s, 40km, 20.2g’s Reentry Experiment Complete at Mach < 0.7 (707s, 28km) Coast… Actuate CG offset system 628s, 127km (1s duration) Start Aeroshell Inflation 436s, 448km (86s to 52KPa [7.5psi]) (186s to 138KPa [20psi]) ACS Reorientation 587s, 260km (40s duration) NIACS damps rates 91s (10s duration) LOS by land radar & TM 910s, 10.5km Vent NIACS and Inflation System Gas Bonus CG Offset Maneuvers Recovery Attempt - Unsuccessful IRVE-3 Mission Events 6/21/2013IPPW-102

Mission Objectives (Results) IRVE-3, 7/23/12 1)Demonstrate reentry survivability of an inflatable with flight relevant heating. (Saw peak heat flux 14.4W/cm2, peak deceleration 20.2G’s.) 2)Demonstrate the effectiveness of a movable CG on the flight L/D of an inflatable. (Reentered with L/D=.17, lift up. Shifted to lift down after reentry; inflatable essentially acted as a rigid body.) IRVE-II, 8/17/09 1)Flight demonstration of inflation and reentry survivability. (Inflation system held pressure in RV. RV stable in hyper/super/trans/subsonic flight.) 2)Assess thermal and drag performance of an inflatable RV. (Worked as planned.) 3)Collect flight data for comparison with analysis & design. (Worked as planned.) IRVE (a.k.a. IRVE-I), 9/6/07 Same objectives that were re-used on IRVE-II. Launch vehicle failed to release payload. (IRVE-II build-to-print re-flight) Demonstrated could pack and deploy inflatable structure, flexible TPS with negligible damage to the materials. 6/21/2013IPPW-103

IRVE-3 Reentry Vehicle 3m [118”] diam inflatable aeroshell with flexible TPS on forward surface Centerbody houses inflation system, CG offset mechanism, telemetry module, power system (batteries), ACS, cameras Inflatable aeroshell packs to 18.5” diam inside nose cone for launch Restraint cover holds aeroshell packed for launch; pyrotechnic release Inflation system fills aeroshell from 3000psi Nitrogen tank Attitude control system uses cold Argon thrusters to reorient for entry CG Offset mechanism allows evaluation of inflatable aeroshell L/D RV entry mass 281kg 6/21/2013IPPW-104 Stowed (18.5”) 22” diam 18.5” diam Inflation System CG Offset System TM & Power ACS Cameras Deployed (3m [118”] diam) Inflatable Flexible TPS T1 T2 T3 T4 T5 T6 T7 Structure Nextel Kapton/Kevlar Aeroheating and Dynamic Pressure TPS Layup Pyrogel

IRVE-II upgrades to IRVE-3 Same: stacked torus structure, 3m diameter, 60° cone angle Total redesign of inflatable structure (ILC  HDT/Airborne); more robust (3.5  20 psi); lower leak rate Upgraded TPS: – IRVE-II was demo of inflation & viability, negligible heating, no TPS insulation – IRVE-3 upgraded to a flight-relevant layup, Nextel over Pyrogel Replaced Teflon nose with TPS-covered aluminum one – Nose instrumentation was not folded during packing, more sensors viable – Sharpened nose radius, to raise stagnation heat flux on TPS Increased instrumentation: Added 5 heat flux gauges & pressure ports centered on stag pt; added IMU & GPS; more thermocouples; 4 cameras for 360° view Improved inflation system: Used metering valve that closed when inflatable was full, instead of dumping gas overboard through pressure relief valves Larger sounding rocket produced higher apogee (218  469km) More hardware in larger centerbody (10.75  22in), with same diameter aeroshell, raised ballistic coefficient 12.5  26.9kg/m 2, raised heat flux 2.2  14.4W/cm 2, G’s 8.5  /21/2013IPPW-105 

Packing the IRVE-3 Aeroshell NC-machined cap attached to nosecone air spring – Helps support aeroshell during launch, pushes nosecone clear in flight Volume allocated inside LV nosecone: 7966in 3 Final volume used (laser scan): 5994in 3 Final packed density 39lb/ft 3 6/21/2013IPPW-106 Aeroshell attached to inflation system skin, then packed     

IRVE-3 Flight Video 6/21/2013IPPW-107

Surprise: Pothole in the Sky At 46km, deceleration dropped from 16 to 14.5G’s for 100ms. Registered at same time on multiple sensors. Best explanation: 11% local drop in density. (Such drops are not in GRAM, but have been seen before in Shuttle reentry flights.) Structural engineer used data to verify modal vibration frequencies 6/21/2013IPPW-108

IRVE-3 TPS Temperatures Thermocouple stacks in TPS showed expected heating trends Lower peak values than expected; maximum temperature reading was 387C Heat flux measurements agreed with trajectory reconstruction Large (0.063in) thermocouple size gave slow response; missed peak temps Thermocouple beads were not in good thermal contact with low-density TPS 6/21/2013IPPW-109

IRVE-3 Centerbody Temperatures Outer surfaces warmed to 150C during launch, then cooled Camera deck was covered during launch, then heated to 50C from electrical power & weak entry heating Inflation system structure stayed at room temperature throughout flight (protected by TPS, and position down in entry cone) 6/21/2013IPPW-1010 Reentry

IRVE-3 Recovery Attempt RV splashdown 1.8  long, ~50 miles beyond nominal Radar track provided latitude/longitude for recovery Surveillance aircraft found object in water ~1 mile from predicted location; had 1hr loiter fuel after splashdown Recovery boat needed ~2hrs to reach splashdown location Debris from damaged fishing boat; not our hardware. 6/21/2013IPPW-1011 Aircraft SurveillanceView from Recovery Boat

The Future IRVE-3 showed an inflatable aeroshell can handle a flight-relevant reentry environment, and that an offset CG can be used to steer an inflatable. Future flights will hopefully demonstrate the increased capabilities that the HIAD project has developed in parallel with IRVE-3. TPS capabilities are now more than 3x higher than what IRVE-3 used. Several proposals exist for HIAD demonstrations from Earth orbit, which will hopefully pave the way to eventual flight use. 6/21/2013IPPW-1012

Thanks Many thanks to the entire IRVE-3 team and all those who supported us for their long hours and dedication. 6/21/2013IPPW-1013

For More Information 1. IRVE-3 Post-Flight Analysis Review, NASA Langley Research Center, March Dillman R. A., Hughes S. J., Bodkin R. J., Bose D. M., Del Corso J., and Cheatwood F. M., Flight Performance of the Inflatable Reentry Vehicle Experiment II, 7 th International Planetary Probe Workshop, Barcelona, Spain, June Dillman R. A., Gsell V. T., and Bowden E. L., Attitude Control Performance of IRVE-3 (AAS ), 36 th Annual AAS Guidance & Control Conference, Breckenridge, Colorado, February Olds A. D., Beck R. E., Bose D. M., White J. P., Edquist K. T., Hollis B. R., Lindell M. C., Cheatwood F. M., Gsell V. T., and Bowden E. L., IRVE-3 Post- Flight Reconstruction (AIAA ), 22 nd AIAA Aerodynamic Decelerator Systems Technology Conference, Daytona Beach, Florida, March Findlay J. T., Kelly G. M., and Troutman P. A., FINAL REPORT: Shuttle Derived Atmospheric Density Model (NASA CR ), December Hughes S. J., Cheatwood F. M., Calomino A. M., Wright H. S., Wusk M. E., and Hughes M. F., Hypersonic Inflatable Aerodynamic Decelerator (HIAD) Technology Development Overview, 10 th International Planetary Probe Workshop, San Jose, California, June /21/2013IPPW-1014