DRYDEN FLIGHT RESEARCH CENTER - NEWS ROOM: NEWS RELEASES: DRYDEN F-15B SUPPORTS F-5 SHAPED SONIC BOOM DEMONSTRATION



DRYDEN F-15B SUPPORTS F-5 SHAPED SONIC BOOM DEMONSTRATION <h3>March 
25, 2002</h3> <h4>Release: 02-17</h4> Printer Friendly Version 
NASA is part of a team seeking quieter sonic booms. NASA's F-15B 
Research Testbed aircraft recently flew in the supersonic shock wave 
of a U.S. Navy F-5E in support of the F-5 Shaped Sonic Boom 
Demonstration (SSBD) project, part of the Defense Advanced Research 
Projects Agency's (DARPA) Quiet Supersonic Platform (QSP) program.

The flights originated from the NASA Dryden Flight Research Center at 
Edwards, Calif.

Four flights were flown in order to measure the F-5E's near-field 
(close-up) sonic boom signature at Mach 1.4, during which more than 
50 shockwave patterns were measured at distances as close as 100 feet 
below the F-5E.

The F-15B's specially-instrumented noseboom recorded static pressure 
measurements while flying behind and below the F-5E. This provided a 
baseline measurement of the F-5E's sonic boom characteristics. 
Differential Global Positioning System (GPS) receivers on both 
aircraft yielded relative aircraft position.

Northrop Grumman Corporation's Integrated Systems sector of El 
Segundo, Calif., intends to modify the F-5E aircraft into a Shaped 
Sonic Boom Demonstrator in an effort to reduce its sonic boom. The 
U.S. Navy aircraft is based at Fallon Naval Air Station in Fallon, 
Nevada. The data provided by Dryden's F-15B is assisting Northrop 
Grumman's and DARPA's efforts, as well as helping assess SSBD flight 
test techniques.

In addition to the airborne data collected by the F-15B, sonic boom 
data was gathered on the ground by two Dryden-developed Boom 
Amplitude and Direction Sensors (BADS) in order to obtain 
ground-level sonic boom signature data. Twenty-five sonic booms from 
the F-5E and F-15B were recorded.

Dryden has expertise in air and ground-based sonic boom measurement 
techniques, having accomplished several sonic boom studies over the 
years. In 1995, Dryden's F-16XL-1 aircraft probed the shockwave of 
one of Dryden's SR-71 aircraft.

"The flight data show fine details unseen in the preflight 
predictions," said Ed Haering, Dryden's principal investigator for 
sonic boom studies. "Based on these details, the Computational Fluid 
Dynamic (CFD) grid density was increased. Preliminary flight data 
agree well with the CFD predictions over most of the region, with an 
adjustment needed to the predictions in the region of the engine 
inlet. These flight data allow the QSP team to validate prediction 
tools to design aircraft with lower sonic booms," Haering said.

DARPA and Northrop Grumman plan to fly the F-5E in the fall with a 
special fairing designed to reduce the aircraft's sonic boom. 
Dryden's F-15B will again fly in the Shaped Sonic Boom Demonstrator's 
shock waves to record changes produced by the F-5E modifications.



--nasa--

Note to Editors: High resolution photos of the F-15B and F-5E are 
available on-line at: /centers/dfrc or by calling Gray Creech at 
(661) 276-2662.        

	
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