A series of up to 10 flights by the NASA Dryden Flight Research Center with a high-speed SR-71 aircraft to study the characteristics of sonic booms will begin this month in the vicinity of Edwards AFB.
First flight in the series is scheduled for Jan. 25, 1995 with others to be flown about once every other week through the month of March 1995.
The flights are being conducted for NASA's Langley Research Center, Hampton, Va., as part of the agency's High Speed Research program dedicated to developing technologies for a new generation of economically viable and environmentally compatible high-speed civilian transports.
During the study, engineers will record how sonic booms are affected by the atmosphere, from the aircraft to the ground. The data will help aerospace scientists learn how to predict the intensity of sonic booms. This information could help designers contour the shape of future supersonic aircraft to reduce sonic boom noise levels.
Residents under the flight paths can expect to hear several light to moderate sonic booms during each research flight. While the sonic booms from the study may cause a person to be startled, NASA officials say they will not be intense enough to cause personal injury or structural damage.
The flights will be in two established supersonic corridors, with sensors on the ground recording the sonic boom pressure waves. On each flight, two other NASA aircraft will also be taking sonic boom measurements. One will be an F-18 flying subsonic between the SR-71 and the ground. The other aircraft, a NASA F-16XL, will be flying near the SR-71 to measure the sonic boom at distances as close as 200 feet below and to the rear.
First several flights will be in the east-west "Black Mountain" supersonic corridor, a 10-mile wide band of airspace north of State Hwy. 58 extending from Coyote Lake, northeast of Barstow, to a point between California City and U.S. Hwy. 395. Centerline of the corridor is about 17 miles north of State Hwy. 58.
The remaining missions will be flown in a 20-mile wide supersonic corridor aligned east-northeast to west-southwest. The corridor runs from the Baker, Calif., area to the western tip of Antelope Valley, with the centerline passing over Boron, the northern portion of Edwards, and the Soledad Mt. area between Rosamond and Mojave. Sensors for flights in this corridor will be located in the northern portion of Edwards and north of State Hwy. 58.
During each flight, the SR-71 and the accompanying F-16XL are scheduled to fly at least once in each direction, producing two sonic booms on each pass. Speeds to be flown by the two aircraft will range between Mach 1.25 and Mach 1.8. (Mach 1 is the speed of sound, with actual speed in miles per hour dependent on altitude and atmospheric conditions.) Altitudes will be at least 30,000 feet on each flight.
Both high speed corridors have been used for decades by NASA and military test and research aircraft.
Sonic booms are created by air which reacts like a fluid to an aircraft as it nears the speed of sound. Air molecules are pushed aside and form a shock wave much like a boat creates a bow wave. The shock wave forms a cone of pressurized air molecules which move outward and downward to spread across the landscape along the flight path. The sharp increase of pressure is heard as the sonic boom.
Sonic boom intensity is governed by several factors such as weight, size, and speed of the aircraft, plus altitude, vehicle attitude and flight path, and weather or atmospheric conditions.
Sonic boom studies were carried out by NASA and the Air Force in the late 1950s and early 1960s, but those studies did not produce the type of information needed for the current industry effort geared towards development of quieter civilian jet transports.
- nasa -
Editors Note: Photographs of the SR-71 and F-16XL can
be obtained from the Dryden Flight Research Center Public Affairs
Office at 805-258-3447. These photos also are available on the
World Wide Web via Internet at address: http://www.dfrc.nasa.gov/PhotoServer/photoServer.html
gopher://www.dfrc.nasa.gov/11/PhotoServer/
ftp://ftp.dfrc.nasa.gov/pub/PhotoServer/
Public Affairs Office
NASA Dryden Flight Research Center
Edwards, Calif. 93523
(805) 258-3447
pao@news.dfrc.nasa.gov
Modified: January 25, 1995