Quiet Spike was a collaborative program between

Gulfstream Aerospace Gulfstream Aerospace Corporation is an American aircraft company and a wholly owned subsidiary of General Dynamics. Gulfstream designs, develops, manufactures, markets, and services business jet aircraft. Gulfstream has produced more than 2,000 ...

and

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeedin ...

Dryden Flight Research Center The NASA Neil A. Armstrong Flight Research Center (AFRC) is an aeronautical research center operated by NASA. Its primary campus is located inside Edwards Air Force Base in California and is considered NASA's premier site for aeronautical rese ...

to investigate the suppression of

sonic boom A sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to ...

s. The patent was published with the

United States Patent and Trademark Office The United States Patent and Trademark Office (USPTO) is an agency in the U.S. Department of Commerce that serves as the national patent office and trademark registration authority for the United States. The USPTO's headquarters are in Alex ...

in 2004 and is owned by Gulfstream Aerospace.

History

The program was intended to develop technology that may allow next generation

supersonic transport A supersonic transport (SST) or a supersonic airliner is a civilian supersonic aircraft designed to transport passengers at speeds greater than the speed of sound. To date, the only SSTs to see regular service have been Concorde and the Tupol ...

s to overfly populated areas at above Mach 1 ( the speed of sound) without the high intensity of sonic boom that proved problematic for first generation supersonic transports such as

Concorde The Aérospatiale/BAC Concorde () is a retired Franco-British supersonic airliner jointly developed and manufactured by Sud Aviation (later Aérospatiale) and the British Aircraft Corporation (BAC). Studies started in 1954, and France an ...

(''c.f.'' Operation Bongo). The boom caused by Concorde generated substantial public opposition in the United States and eventually in other countries around the world with airspace the aircraft was supposed to fly through. This opposition made it impossible for Concorde to be a commercial success. The sonic boom issue was also a significant factor in the eventual cancellation of the

Boeing 2707 The Boeing 2707 was an American supersonic passenger airliner project during the 1960s. After winning a competition for a government-funded contract to build an American supersonic airliner, Boeing began development at its facilities in Seattl ...

. Shock waves develop around aircraft as they near Mach 1 (1225.0 km/h). At ground level, these are perceived as a loud double boom or bang. Their intensity varies due to factors such as weather, refraction from different layers of atmospheric density, and size of the aircraft, but in general, from a supersonic aircraft of the size of a civilian airliner, the overpressure created at ground level is enough to rattle windows. For example, the sonic boom from the Concorde traveling at a speed of Mach 2 (2450 km/h) was about (pound per square foot). Because of sonic boom intensity, many countries now prohibit supersonic overflight over land or population centres. The

FAA The Federal Aviation Administration (FAA) is the largest transportation agency of the U.S. government and regulates all aspects of civil aviation in the country as well as over surrounding international waters. Its powers include air traffic m ...

prohibits supersonic flight over land, except in special military flight corridors. The Quiet Spike is able to suppress sonic booms somewhat, but a Quiet Spike alone is not effective enough to circumvent the current ban on supersonic overflight. Various structural approaches have been proposed to mitigate sonic booms, mainly focusing around changes to aircraft noses, the use of chines, changes in aircraft planform and even creating pathways through the aircraft structure to mitigate parasitic drag that leads to shock waves. As part of the Quiet Spike project, a retractable, long lance-like spike was mounted on the nose of NASA Dryden's

F-15B The McDonnell Douglas F-15 Eagle is an American twin-engine, all-weather tactical fighter aircraft designed by McDonnell Douglas (now part of Boeing). Following reviews of proposals, the United States Air Force selected McDonnell Douglas' ...

research testbed aircraft. When in the 'fully retracted' position for take-offs and landings, the spike was long. When fully extended, the boom added two stages or ''states'', to reach a total length of . The ''Forward boom state'' was long and had the smallest diameter of the three, while the ''Mid-Boom State'' was long and the second largest in diameter. The spike, made of

composite material A composite material (also called a composition material or shortened to composite, which is the common name) is a material which is produced from two or more constituent materials. These constituent materials have notably dissimilar chemical or ...

s, creates three small shock waves that travel parallel to each other all the way to the ground, producing less noise than typical shock waves that build up at the front of supersonic jets. After the project's first flight on 10 August 2006, several more flights put the system's structural integrity to the test before moving on to sonic boom suppression measurements. The program concluded in February 2007, having completed over 50 flights, more than double those completed on the SSBD project two years earlier. Project milestones * First flight - 10 August 2006 * First in-flight extension of the Quiet Spike - 25 September 2006 * First supersonic test point - 20 October 2006 * Near field probing by 2nd F-15 – 13 December 2006 * Mach 1.8 test point - 19 January 2007 * Landing with Quiet Spike extended - 19 January 2007 * Return to Savannah, GA for demod - 14 February 2007 On March 4, 2008, the NASA-Gulfstream Quiet Spike team was awarded the Aviation Week Laureate Award in the Aeronautics/Propulsion category.Aviation Week 2008 Laureate Award Winners
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References

''Aviation Week'' article

External links

Savannah Morning News Article

Interview with NASA Ops Engineer - Quiet Spike Program

{{Supersonic transport NASA programs Aerospace companies of the United States General Dynamics

History

See also

References

External links