Fixing the Sound Barrier The DARPANASANorthropGrumman Shaped Sonic Boom Flight Demonstration

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Fixing the Sound BarrierThe DARPA/NASA/Northrop-
GrummanShaped Sonic Boom Flight Demonstration

• Peter G. Coen, NASA
• Roy Martin, Northrop Grumman
• EAA AirVenture
• Oshkosh, Wisconsin
• July 2004

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Shaped Sonic Boom DemonstrationSSBD

• 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

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Sonic Boom Basics
Multiple Shock Waves of Differing Strengths
Shocks begin to merge
All Shocks merged into N-wave
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Sonic Boom Calculation Approaches
Whitham-Walkden Theoretical
Computational
Equivalent Area AE
Equivalent Length AE
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Theory of Sonic Boom Minimization Through
Aircraft Shaping
Minimum Initial Shock
Minimum Overpressure
George and Seebass, 1969
Shock Strength and Position Controlled
Multiple Shocks of Differing Strengths
Coalescence Prevented
Shocks begin to Coalesce
Shocks Coalesce into N-wave
Shaped Boom at the Ground
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SSBD Background Key Elements of Theory Validated
in Previous Programs
Noise Acceptability Benefit Verified Sullivan
1990
Vehicle Design Approach Verified Darden and
Mack, 1979
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SSBD Provides a Missing Piece of the Puzzle
Design
Through Ground Measurement of Booms from
Modified and Unmodified F-5Es
Demonstrate Shaped Boom Propagation in Real
Atmosphere
Design Mach 1.4
Noise Acceptability
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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
• Very High Overall Fineness Ratio
• Lightweight
• Modification Is Relatively Low RiskDue to
  Similarity with F-5 Family
  
• Extensive Database of Modified Forebodies with
  ComprehensiveWind Tunnel and Flight Testing
  
• Cost-Effective Test Approach
• Limited Wind Tunnel Testing and CFDAnalysis
  Required for F-5 Mod
  
• Low Aircraft Operating Cost
• Supersonic Performance Capabilitywith Margin

Initial Design
Final Design
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Build-Up Approach To Development Validation
FOR PUBLIC RELEASE
Boom Tunnel Tests
Extensive CFD
Inlet Shock Flight Test
NASA Dryden Feb 02
NASA Glenn Mar May 02
Mod Shape Defined Jan 02
Correlations Completed
SC Tunnel Test
Force Tunnel Test
NGC LSWT Aug 02
AEDC 4T Oct 02
Pre-FRR - 1/03
IDRs - 12/01 2/02
PDR - 3/02
CDR - 7/02
FOR PUBLIC RELEASE
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SSBD F-5E Handling QualitiesEngineering
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)

FOR PUBLIC RELEASE
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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
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Fabrication Flight Operations
FOR PUBLIC RELEASE
Mod Nose Attached
USN F-5E Arrives NGSA
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 Ferry Flights
Back-to-Back Probe Flights
21 Flawless FlightsOver 1 Month!
FOR PUBLIC RELEASE
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SSBD F-5E Cockpit Modifications
FOR PUBLIC RELEASE
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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
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First Flight of SSBD F-5E
FOR PUBLIC RELEASE

• 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)

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Envelope Expansion Flights

• Maneuver Block
• Pitch Doublet
• Yaw Doublet
• Steady Sideslips
• 30 Bank to Bank
• Windup Turn
• (Augs-On then Off)

FOR PUBLIC RELEASE
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Cross Country Ferry Flights
FOR PUBLIC RELEASE
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Back-to-Back Data Flight27 August 2003
FOR PUBLIC RELEASE
(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 Super
sonic Corridor
F-5 Pilots
Roy Martin CDR Darryl Spike Long L
CDR Dwight Tricky Dick
FOR PUBLIC RELEASE
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SSBD Flight Path
FOR PUBLIC RELEASE
FOR PUBLIC RELEASE
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Ground Recording Array Setup
FOR PUBLIC RELEASE
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First-Ever Shaped Sonic Boom Recorded 27 August
2003
FOR PUBLIC RELEASE
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
FOR PUBLIC RELEASE
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Lessons Learned from Initial Tests

• Florida in July has BIG Thunderstorms in PM!
• Navy Flight Clearances Are Difficult and
  Expensive, but Great Confidence Builders
  
• Dont 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
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Test Background/Objectives
FOR PUBLIC RELEASE
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
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Shaped Sonic Boom Experiment
SSBE Experiment Designed to Collect Quality Data
from Many Sources

• Test Summary
• 21 flights in 9 days
• 8 flights back to back with baseline F- 5E
• 4 flights with F-15 probe aircraft
• 45 probe data sets
• 13 flights with glider
• 1300 boom recordings
• 2 focus booms recorded

Test Schematic
F-5 SSBD operated by Northrop Grumman generates
shaped boom over sensor array
Unmodified F-5E from USN VFC-13 used to generat
e baseline
boom signature
Microphone on USAF Test Pilot School glider
measures boom above turbulence layer
DFRC F-15 probes pressure field below F-5 SSBD
30,000 ft
Boom senor array (42 sensors total), on off t
he flight track NASA, Wyle Labs, NGC, Gulfstrea
m, Eagle
8,000 ft
North Edwards AFB Runway
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Revised Ground Track
FOR PUBLIC RELEASE
Shaped Sonic Boom Experiment
FOR PUBLIC RELEASE
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FOR PUBLIC RELEASE
SSBE Test Summary
Shaped Sonic Boom Experiment

• Met or Exceeded All Flight Test Goals
• 21 Test Flights Conducted January 1222, 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
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Initial SSBE Flight Test Results
FOR PUBLIC RELEASE
Shaped Sonic Boom Experiment
F-15B Probe Data
Glider Data
Ground Data
FOR PUBLIC RELEASE
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SSBD/SSBE Program Summary
FOR PUBLIC RELEASE
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
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A Tribute To The SSBD Team
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SSBD/SSBE Test and Support Team
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Whats Next for QSP?
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Video