Dynamic Event Observations from the Orion Exploration Flight Test 1 (EFT-1) Mission Adam Wigdalski Orion Loads and Dynamics SCLV 2015 The Aerospace Corporation, El Segundo, CA 2015 Lockheed Martin Corporation. All Rights Reserved
Agenda Exploration Flight Test 1 (EFT-1) Mission Overview Development Flight Instrumentation (DFI) Suite Overview CLA Responses Liftoff Acoustics Ascent Acoustics Structural Vibration Launch Abort System Separation Dynamics Landing Summary References Acronyms List 2
EFT-1 Mission Overview Dynamic Loading Events Drogue Deploy Main Deploy FBC Separation CM/SM Separation LAS Separation SM Fairing Jettison Riser Cutter LV Separation Fire Transonic / Max Q : Image Credit: NASA, See Reference Slide for more details 3
Development Flight Instrumentation (DFI) Suite Overview 258 Accelerometer Channels 36 Microphone Channels Also had strain gages, thermal sensors, static pressure transducers, string potentiometers, cameras Accelerometer Channels Launch Abort System (LAS) 37 10 Crew Module (CM) 168 8 Service Module (SM 22 2 SM Fairings 31 16 Microphone Channels Notes 1 No mics penetrate the CM Outer Mold Line (OML) (i.e. no re-entry acoustic data collected) 2 No mics between the Fairing Inner Mold Line (IML) and the SM Structure : Image Credit: NASA, See Reference Slide for more details 4
Comparison of CLA Predictions with Flight Data Shock Response Spectrum (SRS) Comparison Launch Vehicle provider conducted Delta IVH/MPCV Coupled Loads Analysis (CLA) for launch events SRS envelopes of major flight events were generally conservative Generally good spectral content consistency between CLA responses and flight data Some exceedances observed in localized frequency bands Note: LAS Jettison event is included in flight data but not CLA prediction EFT-1 Response CLA Prediction Near vs CM/LAS Flight SRS Interface w/o LAS Jettison (Near CM/LAS Interface Axial Direction) Axial Direction [2] EFT-1 Response CLA Prediction Near vs Flight CM/LAS SRS w/o Interface LAS Jettison (Near CM/LAS Lateral Interface Direction Lateral [2] Direction) 10dB CLA Predictions Flight Data CLA Predictions Flight Data 5
Liftoff External Acoustics Forcing Function (FFN) Observations Flight data well below FFN Forward of SM FFN intensity trends downward as distance from launch pad increases Structural vibration environments from flight generally follow this trend as well Strong axial correlation in flight data suggest non-diffuse environment Flight Data Axial Coherence Between Two SM Sensors [2] LAS Zone: 8-14 db below FFN Coherence SM Zone: 4-8 db below FFN [2] Frequency (Hz) 6
Ascent External Acoustics Data Quality Review External transducers were operated outside 1psig defined linear range during Ascent but still provided usable data that was higher quality than expected Sensors installed in a manner to prevent low frequency signal corruption Data were not clipped or saturated and sensors were not damaged Spectral content of flight data correlates very well with wind tunnel test data [3] Dynamic Ranging was adequate to capture peaks from Liftoff and provided sufficient resolution during Ascent Pressure Pressure Time History EFT-1 External Microphone Unexpected DC Content from AC-Coupled Sensor Running Average technique used to remove DC content Shock wave passage Time [2] 7
Correlation of Linear Joint Vibration at Liftoff LAS/CM Retention and Release Mechanism Example Well predicted by analytical techniques [2,4] 8
Correlation of Nonlinear Slider Joint Vibration at Liftoff Propulsion Tank Example Primary Mode missed by analytical techniques Low frequency axial tank mode predicted from linear modelling approach, resulting in significant response of the secondary structure Flight data suggests that any low frequency axial motion of the tank was not reacted by the secondary structure Note: Other two orthogonal directions with linear joints were well predicted [2,4] 9
Launch Abort System Separation Dynamics Rigid Body Displacement and CM Reaction Rigid body displacement measured during flight was well predicted Flight measurement from high rate string potentiometers Event produced observable dynamic response on CM in the axial direction Oscillation frequency and amplitude correlates reasonably well with prediction String Pot vs. Rigid Body Prediction LAS Displacement Flight Measurement Simulation CM Response Acceleration 2 1.5 1 0.5 0-0.5-1 EFT-1 Flight Data CM Accelerometer Response EPOCH:0:6:19.6 CZCCA1B: CM PV Barrel Aft Bay (g) -1.5-2 Time [2,5] -2.5 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 Time (sec) Time [2] 10
Landing Reconstruction Analysis Overview Initial Conditions (IC) determined from flight data CM attitude and velocity at impact provided by NASA GN&C Wave state estimated by comparing flight accelerations with predictions across a large number of impact ICs Landing accelerations suggest event was a 44 th percentile condition Peak acceleration responses from reconstruction analysis compares well with flight data Flight Imagery 0 msec 200 msec Analysis [6] Acceleration Heat Shield Skin Structure Prediction Flight Data Acceleration Heat Shield Stringer Prediction Flight Data : Image Credit: NASA, See Reference Slide for more details Time [2,6] Time [2,6] 11
Summary High quality data set available from the EFT-1 flight test Spacecraft experienced nominal loads/environments during EFT-1 mission Analytical techniques generally predicted flight environments well and retained margin over flight conditions for all mission events, with few exceptions Post-flight reconstruction analyses provide an opportunity to improve modeling capabilities 12
References 1 NASA Website: http://www.nasa.gov/exploration/systems/orion/gallery/index.html?id=351887 http://www.nasa.gov/exploration/systems/orion/videos http://www.nasa.gov/exploration/systems/orion/gallery/index.html?id=351870 http://www.nasa.gov/sites/default/files/files/jsc_orioneft-1_presskit_accessible.pdf http://www.nasa.gov/sites/default/files/thumbnails/image/8513329725_2f7bf70062_o.png 2 ERB-ORION-15-0803, Section 2.6 Loads and Dynamics, A. Wigdalski, LMSSC, 2015 3 Ascent Aeroacoustic Environment of MPCV Comparison between EFT1 flight and 51AS wind tunnel data (preliminary), J. Panda, NASA ARC, 2015, verii_eft1_externalmics_vs_51aswindtunneltest.pdf 4 EFT-1 BEA v5a (Verification) Responses, C. Fransen, LMSSC, 2014 5 MPCV-LD-13-053, LAS Jettison Analysis, E. Alvarez, LM IS&GS, 2013 6 LM/NASA Orion Loads Panel, Recap of EFT-1 Post-Flight Landing Assessment, M. Baldwin, LMSSC, 2015 13
Acronyms BEA Boundary Element Analysis CLA Coupled Loads Analysis CM Crew Module DAF Diffuse Acoustic Field EFT-1 Exploration Flight Test 1 FFN Forcing Function GN&C Guidance Navigation and Control IML Inner Mold Line LAS Launch Abort System LMSSC MPCV Multi-Purpose Crew Vehicle OML Outer Mold Line PWF Propagating Wave Field R&R Retention and Release (Mechanism) SM Service Module SPL Sound Pressure Level SRS Shock Response Spectrum 14
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