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Fixing the Sound Barrier The DARPA/NASA/Northrop-Grumman Shaped Sonic Boom Flight Demonstration Peter G. Coen, NASA & Roy Martin, Northrop Grumman EAA AirVenture Oshkosh, Wisconsin July 2004 Shaped Sonic Boom Demonstration SSBD First ever FLIGHT demonstration of sonic boom Shaping Design, fabrication and test using a surrogate aircraft Nose modification of an F-5E Fighter Primarily funded by DARPA, Northrop and NASA Extremely successful government/industry collaboration 5 U.S. Government agencies 8 U.S. aerospace companies Sonic Boom Basics Multiple Shock Waves of Differing Strengths Shocks begin to merge Overpressure Dp Impulse Duration All Shocks merged into “N-wave” Rise Time Sonic Boom Calculation Approaches Whitham-Walkden Theoretical Computational Equivalent Area AE Equivalent Length AE Theory of Minimum Initial Shock Equivalent Area Sonic Boom Lift Minimization Volume Minimum Overpressure Through Length Aircraft Shaping George and Seebass, 1969 Multiple Shocks Shock Strength of Differing and Position Strengths Controlled Coalescence Prevented Shocks begin to Coalesce Shocks Coalesce into “N-wave” Shaped Boom at the Ground SSBD Background: Key Elements of Theory Validated in Previous Programs A A = 1.3. psf B 8 7 Rise Time 6 0.25 5 0.5 Mean 0.75 Loudness 4 1 Rating 3 B/A 2 1 0 1 2 3 Rise Time, ms Noise Acceptability Benefit Verified: Sullivan 1990 Vehicle Design Approach Verified: Darden and Mack, 1979 SSBD Provides a Missing Piece of the Puzzle Design … Through Ground Measurement of Booms from Modified and Unmodified F-5Es Demonstrate Design Mach 1.4 Shaped Boom Shock Thickening Adjusted Ground Boom Signature Comparisons Propagation in 1.4 1.2 1.0 M = 1.40 h = 32 kft. Tanh 1/P Modification Real 0.8 0.6 0.4 Atmosphere… 0.2 DP - psf 0.0 -0.2 -0.4 -0.6 F-5SSBD SBD-24b @ 12,700 lbs. -0.8 F-5E F-5E @ 11,200 lbs. -1.0 -1.2 -1.4 0 10 20 30 40 50 60 70 80 90 100 Time - msec Noise Acceptability Key to SSBD Success: F-5E Aircraft Configuration Is Very Amenable to the Type of Forebody Modifications Required to Produce a Shaped Boom Signature Long Nose, Blended Canopy, and Inlets Relatively Far Back F-5E Very High Overall Fineness Ratio Lightweight RF-5E Modification Is Relatively Low Risk Due to Similarity with F-5 Family Extensive Database of Modified F-5F Forebodies with Comprehensive Wind Tunnel and Flight Testing F-5 Aircraft Forebodies Cost-Effective Test Approach Limited Wind Tunnel Testing and CFD Analysis Required for F-5 Mod Initial Design Low Aircraft Operating Cost Supersonic Performance Capability with Margin Final Design FOR PUBLIC RELEASE Build-Up Approach To Development & Validation Extensive CFD Inlet Shock Flight Test Boom Tunnel Tests NASA Dryden NASA Glenn Feb 02 Mar & May 02 Mod Shape Defined Jan 02 Correlations Completed SSBD WTM-2 Near-Field Pressures S&C Tunnel Test Force Tunnel Test M = 1.367, CN = 0.132, h/L = 1.5, = 0 o 0.04 0.03 0.02 0.01 DPlocal / P local freestream 0.00 -0.01 -0.02 -0.03 Euler - 24b WTM-2 @ MFR = 0.76 -0.04 -0.05 24b4 WT Data @ MFR = 0.76 - 0.80 - Rdg. 143 (P3) 24b4 WT Data @ MFR = 0.76 - 0.80 - Rdg. 157 (P4) NGC LSWT AEDC 4T -0.06 Aug 02 Oct 02 35 40 45 50 55 60 65 70 75 Along Track (Model) - inches IDRs - 12/01 & 2/02 PDR - 3/02 CDR - 7/02 Pre-FRR - 1/03 FOR PUBLIC RELEASE SSBD F-5E Handling Qualities Engineering Predictions Longitudinal Stability Comparable F-5F, Minor Reduction Dynamic Stability Damping Directional Stability of F-5SSBD is Comparable to F-5F with 275 Gallon Centerline Tank Directional Stability is Positive for AOA of Planned Flight Envelope Subsonic and Supersonic Handling Qualities Satisfactory and Comparable to other F-5 Configurations (with Stability Augmentaion Engaged) Use Aft CG Limit of F-5F (More Forward than F-5E) 25% MAC L.E. MAC Design C.G. FOR PUBLIC RELEASE Test Aircraft Selection Arranged Loan of Navy F-5E - Destined for “Boneyard” - Extended 50 Flight Hrs Navy Assumed Safety of Flight Risk - Navy Flight Clearance Review - Navy Test Pilot Participation ( CDR “Spike” Long) FOR PUBLIC RELEASE FOR PUBLIC RELEASE Fabrication & Flight Operations USN F-5E Arrives NGSA Mod Nose Attached Fairings Attached Jan 03 Mar 03 Apr 03 Pre-Flight Prep First Taxi First Flight May 03 9 Jun 03 24 Jul O3 Envelope Expansion Back-to-Back & 21 Flawless Flights & Ferry Flights Probe Flights Over 1 Month! FOR PUBLIC RELEASE FOR PUBLIC RELEASE SSBD F-5E Cockpit Modifications Preparation for First Flight Test Plan Approved by NAVAIR Civil Landing Permits from USAF, USN, US Army F-5E Spare Parts from Marines at YUMA MCAS Flight Readiness Reviews: NAVAIR, DARPA, Northrop Grumman, NASA Dryden, NASA Langley Aircraft Prep, EMC, Low and High Speed Taxi Real Time Telemetry for First Flight and Envelope Expansion Flight Tests Pre-position T-38 Chase from Seattle to St. Augustine - Extremely Useful for Test Pilot Proficiency FOR PUBLIC RELEASE FOR PUBLIC RELEASE First Flight of SSBD F-5E Takeoff from St. Augustine (8000 Ft Rwy) Test Area Over the Atlantic (W-158) Boeing T-38 Chase (Mike Bryan) Landing at Cecil Field (12,500 Ft Rwy) Envelope Expansion Flights Maneuver Block: Pitch Doublet Yaw Doublet Steady Sideslips 30 Bank to Bank Windup Turn (Augs-On then Off) FOR PUBLIC RELEASE FOR PUBLIC RELEASE Cross Country Ferry Flights FOR PUBLIC RELEASE Back-to-Back Data Flight 27 August 2003 (45 Second Separation Between Aircraft During Supersonic Run) NAS Fallon VFC-13 F-5E and F-5 SSBD at Palmdale, CA F-5 SSBD Takes Off at Dawn Enroute to EAFB Supersonic Corridor F-5 Pilots Roy Martin CDR Darryl “Spike” Long LCDR Dwight “Tricky” Dick FOR PUBLIC RELEASE FOR PUBLIC RELEASE SSBD Flight Path Edwards AFB Supersonic Corridor 32 FOR PUBLIC RELEASE FOR PUBLIC RELEASE Ground Recording Array Setup FOR PUBLIC RELEASE First-Ever Shaped Sonic Boom Recorded 27 August 2003 Signatures recorded during SSBD back- to-back data flights in the Edwards AFB supersonic flight corridor early morning Flight conditions: Mach 1.36+, Altitude 32,000 ft Design Mach 1.4 Shock Thickening Adjusted Ground Boom Signature Comparisons 1.4 1.2 M = 1.40 1.0 Tanh 1/P Modification h = 32 kft. 0.8 0.6 0.4 0.2 DP - psf 0.0 -0.2 -0.4 -0.6 F-5SSBD SBD-24b @ 12,700 lbs. -0.8 F-5E F-5E @ 11,200 lbs. -1.0 -1.2 -1.4 0 10 20 30 40 50 60 70 80 90 100 Time - msec FOR PUBLIC RELEASE Lessons Learned from Initial Tests Florida in July has BIG Thunderstorms in PM! Navy Flight Clearances Are Difficult and Expensive, but Great Confidence Builders Don’t Depend on Using Ground References for Early Morning Flights into a Rising Sun! Program Will Cost Twice Your Initial Estimate Good Programs Attract Interest & Support Shaped Sonic Boom Theory is Valid FOR PUBLIC RELEASE FOR PUBLIC RELEASE Test Background/Objectives Shaped Sonic Boom Experiment Based on the Success of the DARPA SSBD Program, NASA Created a Follow-On Program to Further Explore the Characteristics and Robustness of Shaped Sonic Booms Using the F-5 SSBD Test Aircraft Up to 21 Test Flights Planned Achieve M1.4, 32k ft. Design Condition Collect Data at Off-Design Conditions Collect Back-to-Back Data with Navy F-5E Collect Near-Field Probing Data with NASA F-15 Collect Data Above Ground Turbulence Layer with USAF TPS Glider Attempt to Record Focused Boom FOR PUBLIC RELEASE Shaped Sonic Boom Experiment SSBE Experiment Designed to Collect Quality Data from Many Sources Test Summary Test Schematic • 21 flights in 9 days • 8 flights back to back with baseline F- 5E F-5 SSBD operated by Northrop • 4 flights with F-15 probe aircraft Grumman generates shaped • 45 probe data sets boom over sensor array • 13 flights with glider • 1300 boom recordings Unmodified F-5E from • 2 focus booms recorded USN VFC-13 used to generate baseline boom signature Microphone on USAF Test Pilot School glider measures DFRC F-15 probes 30,000 ft boom above turbulence layer pressure field below F-5 SSBD Boom senor array 8,000 ft (42 sensors total), on & off the flight track North Edwards AFB Runway NASA, Wyle Labs, NGC, Gulfstream, Eagle FOR PUBLIC RELEASE Revised Ground Track Shaped Sonic Boom Experiment FOR PUBLIC RELEASE FOR PUBLIC RELEASE SSBE Test Summary Shaped Sonic Boom Experiment Met or Exceeded All Flight Test Goals 21 Test Flights Conducted January 12–22, 2004 1 Functional Check Flight 8 F-5 SSBD Solo Flights 8 F-5 SSBD / F-5E Back-to-Back Flights 4 F-5 SSBD / F-15B Probing Flights Repeatable Data Collected Between M1.35 and M1.45 Well Over 1300 Sonic Boom Signatures Recorded by Ground Sensor Array at EAFB North Base USAF TPS Glider Obtained Excellent Data Above Ground Turbulence Layer on 14 Flights 45 Near-Field Probing Measurements Obtained with F-15 Successfully Recorded Focused Boom on 2 Flights Excellent Weather for Meaningful Data Collection Experienced Throughout Test Phase FOR PUBLIC RELEASE FOR PUBLIC RELEASE Initial SSBE Flight Test Results Shaped Sonic Boom Experiment F-15B Probe Data Glider Data Ground Data FOR PUBLIC RELEASE FOR PUBLIC RELEASE SSBD/SSBE Program Summary Shaped Sonic Boom Experiment Shaped Sonic Boom Persistence Theory was Proven in Actual Flight Conditions Sonic Boom Intensity Can Be Reduced Through Aircraft Shaping Shaped Ground Boom Signature for a Supersonic Aircraft Can Be Predicted DARPA and NASA Were Delighted with the Quantity and Quality of the Supersonic Data Mapped Shockwave Propagation Around the Near-Field of SSBD Aircraft, at the Mid-Field Using a Glider, and at the Ground Level in Various Atmospheric Conditions Recorded Boom Focus Data Using ¼ G Pushover Program Data Will be Invaluable to Future Supersonic Aircraft Designs – Allows Designers to Go Forward with Confidence in Ability to Predict Boom Signatures FOR PUBLIC RELEASE A Tribute To The SSBD Team SSBD/SSBE Test and Support Team NAVY • • US W SA YL • NA E RPA LA BS N • DA •E A UMM AG P GR LE TH RO SSBD AE R RO NO USA AM F• US SHAPED SONIC T RE AR FS MY • BO BOOM DEMO UL EIN •G G • LO ON CK T HE HEE AY DM ART I N • R What’s Next for QSP? 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"“Shaped Sonic Boom Demo Program "