https://ntrs.nasa.gov/search.jsp?R=20110011170 2018-12-24T06:56:13+00:00Z NASA/CR–2011-217077 Measured Sonic Boom Signatures Above and Below the XB-70 Airplane Flying at Mach 1.5 and 37,000 Feet Domenic J. Maglieri and Herbert R. Henderson Eagle Aeronautics, Inc., Hampton, Virginia Ana F. Tinetti NCI Information Systems, Inc., Hampton, Virginia April 2011 NASA STI Program . . . in Profile Since its founding, NASA has been dedicated to  CONFERENCE PUBLICATION. Collected the advancement of aeronautics and space science. papers from scientific and technical The NASA scientific and technical information (STI) conferences, symposia, seminars, or other program plays a key part in helping NASA maintain meetings sponsored or co-sponsored by NASA. this important role.  SPECIAL PUBLICATION. Scientific, The NASA STI program operates under the technical, or historical information from NASA auspices of the Agency Chief Information Officer. 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Does not contain extensive  Write to: analysis. NASA STI Help Desk NASA Center for AeroSpace Information  CONTRACTOR REPORT. Scientific and 7115 Standard Drive technical findings by NASA-sponsored Hanover, MD 21076-1320 contractors and grantees. NASA/CR–2011-217077 Measured Sonic Boom Signatures Above and Below the XB-70 Airplane Flying at Mach 1.5 and 37,000 Feet Domenic J. Maglieri and Herbert R. Henderson Eagle Aeronautics, Inc., Hampton, Virginia Ana F. Tinetti NCI Information Systems, Inc., Hampton, Virginia National Aeronautics and Space Administration Langley Research Center Prepared for Langley Research Center Hampton, Virginia 23681-2199 under Contract NNL07AE38T April 2011 The use of trademarks or names of manufacturers in this report is for accurate reporting and does not constitute an official endorsement, either expressed or implied, of such products or manufacturers by the National Aeronautics and Space Administration. Available from: NASA Center for AeroSpace Information 7115 Standard Drive Hanover, MD 21076-1320 443-757-5802 Measured Sonic Boom Signatures Above and Below the XB-70 Airplane Flying at Mach Number 1.5 and 37,000 Feet By Domenic J. Maglieri and Herbert R. Henderson and Ana F. Tinetti ABSTRACT During the 1966-67 Edwards Air Force Base (EAFB) National Sonic Boom Evaluation Program, a series of in-flight flow-field measurements were made above and below the USAF XB-70 using an instrumented NASA F-104 aircraft with a specially designed nose probe. These were accom- plished on three XB-70 flights conducted at a Mach number of about 1.5 at an altitude of about 37,000 feet and at a gross weight of about 350,000 pounds. A total of six supersonic passes were made with the F-104 probe aircraft through the XB-70 shock flow-field; one above the XB-70 on the first flight, two below the XB-70 on the second flight, and three below the XB-70 on the third flight. Separation distances ranged from about 3000 feet above and 7000 feet to the side of the generating aircraft and about 2000 feet and 5000 feet below the generating aircraft. Complex near-field “sawtooth-type” signatures were observed in all cases. In fact, at ground level, the XB- 70 shock waves had not coalesced into the two-shock classical sonic boom N-wave signature, but contained three shocks. The purpose of these in-flight measurements was to gather an additional database on a very large and heavy aircraft to be used in providing a check on and improvement to the generalized theory for predicting sonic boom signatures. Although the tests were successfully completed, the results were never formally documented appearing, only briefly, in a few reports to reflect the nature of the flight tests. The present report documents the results of the XB-70/F-104 probe flight tests and is based upon file copies of most of the original information and database developed in the 1966-67 time period. Included in this report is a description of the generating and probe airplanes, details of the in- flight and ground pressure measuring instrumentation, the flight test procedure and the aircraft in- flight and ground pressure measuring instrumentation, the flight test procedure and aircraft posi- tioning, surface and upper air weather observations and the six measured in-flight pressure time histories from the three XB-70 flights along with the corresponding ground measured signatures. 1 THIS PAGE INTENTIONALLY LEFT BLANK 2 TABLE OF CONTENTS INTRODUCTION - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 7 SYMBOLS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 8 APPARATUS AND METHODS- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9 Generating and Probe Airplanes- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 9 Pressure Measuring Instrumentation- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10 Flight Test Procedures - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -10 Aircraft Positioning - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 11 Weather Observations - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 12 RESULTS- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 12 Inflight Measurements - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 12 Wave Shapes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 12 Peak Positive Overpressures - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 14 Signature lengths- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -15 Ground Measurements - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15 Microphone Set-Up and Characteristics - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 15 Wave Shapes - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 16 Signature Characteristics - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 16 Correlation with Airplane Geometry- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 16 SUMMARY REMARKS- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 17 APPENDIX A DESCRIPTION AND CALIBRATION OF PRESSURE INSTRUMENTATION - - - - - - 18 APPENDIX B DESIGN AND AERODYNAMICS CALIBRATION OF PRESSURE PROBE - - - - - - - 20 Basic Considerations - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20 Present Applications - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 20 WIND TUNNEL TESTS - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21 Introduction - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21 Symbols - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 21 Apparatus and Tests - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22 Test facility and conditions- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22 Test apparatus and procedures- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 22 Measurements - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 Data and Precision- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 Probe Calibration - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 Pressure measurements in vicinity of oblique shock wave - - - - - - - - - - - - - - - - - - - - 23 Results and Discussion- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 Probe calibration at angle of attack- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 23 Probe capability for sensing pressure changes across an oblique shock wave - - - - - - - 24 Probe reflection factors for correcting in-flight measurements - - - - - - - - - - - - - - - - - 25 General comments- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 25 REFERENCES - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 26 3 LIST OF TABLES Table 1 Geometric characteristics of XB-70 airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Table II Summary of XB-70 and F-104 in-flight probe test conditions. . . . . . . . . . . . . . . . . .34 Table III XB-70 flight conditions overhead of ground cruciform microphone array . . . . . . . .35 Table IV Upper air atmospheric data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36 Table V Surface weather observations at EAFB runway 22/04. . . . . . . . . . . . . . . . . . . . . . . .39 Table VI Summary of XB-70 maximum positive overpressures, signature lengths and periods for in-flight probe tests. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 Table VII XB-70 sonic boom signature characteristics measured at ground level with the six microphone cruciform array . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 4 LIST OF FIGURES Figure 1 Photograph of XB-70 delta wing supersonic aircraft used as the sonic boom generator in the present studies. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .42 Figure 2 Three view drawing of XB-70 airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43 Figure 3 Photograph of XB-70 showing windshield-nose ramp positions . . . . . . . . . . . . . . . .44 Figure 4 Area distribution of XB-70-1 vehicle used as shock-wave generation airplane. . . . .45 Figure 5 F-104 airplane with nose-boom probe installation for measuring the shock flow-field in the vicinity of the disturbance generating XB-70-1 airplane. . . . . . . . .46 Figure 6 Photographs of the in-flight recording instrumentation mounted in the F-104 access bay . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47 Figure 7 Principal details and dimensions of full-scale probe used for in-flight measurements and for wind tunnel tests at a Mach number of about 2.01. . . . . . . . . . . . . . . . . . . . .48 Figure 8 Adaptor required to mate specially instrumented noise-boom pressure probe used originally on an F-106 to the NASA F-104 used in present tests. . . . . . . . . . . .49 Figure 9 Schematic of XB-70 and F104 nominal ground tracks showing area in which probe missions were flown and ground measurements were acquired. . . . . . . . . . . .50 Figure 10 Sketches illustrating general position of probe aircraft and generating aircraft. . . . .51 Figure 11 Copy of November 23, 1966 film trace showing in-flight time histories of differential pressures measured in flow-field above XB-70 aircraft. . . . . . . . . . . . . .52 Figure 12 Copy of December 12, 1966 film trace showing in-flight time histories of differential pressures measured in flow-field below the XB-70 aircraft. . . . . . . . . . .53 Figure 13 Copy of December 16, 1966 film trace showing in-flight time histories of differential pressures measured in flow-field below XB-70 aircraft . . . . . . . . . . . . .54 Figure 14 XB-70 flow-field shock-wave signature overpressures . . . . . . . . . . . . . . . . . . . . 55 Figure 15 Comparison of measured and calculated distance between bow-wave and tail-wave of generating airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .57 Figure 16 XB-70 measured sonic boom signatures at ground level following in-flight probe tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .58 5 Figure 17 Diagrams of waveforms and signature characteristics which represent the various categories of measured sonic booms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 Figure 18 Planform and side views of bomber airplane with time history of pressure signature as measured above and below airplane. Signature length has been adjusted to made dis- tance between nose and tail shocks approximately the same as the airplane lengths.60 Figure 19 Response characteristics of pressure instrumentation use for in-flight measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61 o o Figure 20 Steady-state calibration of flight probe at angles-of-attack from -2.5 to 9.5 , as obtained from tests in the Langley 4-foot supersonic pressure tunnel (pressure orifices at bottom of probe). M  p  185 lbs/ft2. . . . . . . . . . . . . . . . . . . . . . . . . .62   Figure 21 Wind-tunnel apparatus and test arrangement for generating and determining the strength of an axisymmetrical disturbance used in obtaining experimental evidence concerning the reflection characteristics of the flight probe . . . . . . . . . 63 Figure 22 Flight-probe capability for sensing static-pressure changes across an axisymmetrical disturbance (bow wave generated by body of revolution), as evidenced by comparison of probe-indicated, survey-indicated, and estimated pressure changes across bow-wave, M 5  6