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Quiet Spike Build-Up Ground Vibration Testing ApproachNASA's Dryden Flight Research Center uses a modified F-15B (836) aircraft as a testbed for a variety of flight research:experiments mounted underneath the aircraft fuselage. The F-15B was selected to fly Gulfstream Aerospace Corporation's (GAC)QuietSpike(TM)(QS) project; however, this experiment is very unique and unlike any of the previous testbed experiments flown on the F-15B. It involves the addition of a relatively long quiet spike boom attached to the radar bulkhead of the aircraft. This QS experiment is a stepping stone to airframe structural morphing technologies designed to mitigate sonic born strength of business jets over land. The QS boom is a concept in Which an aircraft's front-end would be extended prior to supersonic acceleration. This morphing would effectively lengthen the aircraft, reducing peak sonic boom amplitude, but is also expected to partition the otherwise strong bow shock into a series of reduced-strength, non-coalescing shocklets. Prior to flying the Quietspike(TM) experiment on the F-15B aircraft several ground vibration tests (GVT) were required in order to understand the QS modal characteristics and coupling effects with the F-15B. However, due to the project's late hardware delivery of the QS and the intense schedule, a "traditional" GVT of the mated F-1513 Quietspike(tm) ready-for-flight configuration would not have left sufficient time available for the finite element model update and flutter analyses before flight testing. Therefore, a "nontraditional" ground vibration testing approach was taken. The objective of the QuietSpike (TM) build-up ground testing approach was to ultimately obtain confidence in the F-15B Quietspike(TM) finite element model (FEM) to be used for the flutter analysis. In order to obtain the F15B QS FEM with reliable foundation stiffness between the QS and the F-15B radar bulkhead as well as QS modal characteristics, several different GVT configurations were performed. EAch of the four GVT's performed had a specific objective. The overall intent was to provide adequate data which would replicate a "traditional" F-15B QS GVT with actual ready-for-flight hardware. NASA Dryden was tasked with the conduct of the 1st, 2nd and 4th GVT and the 3rd GVT was GAC's responsibility. In order for this build-up GVT approach to be feasible, it was absolutely critical that each GVT configuration matched as closely as possible the connection interface configuration between the and aircraft bulkhead.
Document ID
20090008318
Acquisition Source
Armstrong Flight Research Center
Document Type
Conference Paper
Authors
Spivey, Natalie D.
(NASA Dryden Flight Research Center Edwards, CA, United States)
Herrera, Claudia Y.
(NASA Dryden Flight Research Center Edwards, CA, United States)
Truax, Roger
(NASA Dryden Flight Research Center Edwards, CA, United States)
Pak, Chan-gi
(NASA Dryden Flight Research Center Edwards, CA, United States)
Freund, Donald
(Gulfstream Aerospace Corp. United States)
Date Acquired
August 24, 2013
Publication Date
April 23, 2007
Subject Category
Aircraft Design, Testing And Performance
Report/Patent Number
DFRC-572
Meeting Information
Meeting: 48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference
Location: Waikiki, HI
Country: United States
Start Date: April 23, 2007
End Date: April 26, 2007
Sponsors: American Society of Civil Engineers, American Inst. of Aeronautics and Astronautics, American Helicopter Society, Inc., American Society of Mechanical Engineers, American Society for Composites
Distribution Limits
Public
Copyright
Other

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