The Need for Speed
Everything is in place for the development of a supersonic business jet-except U.S. Federal Aviation Regulations.
- By Ron Swanada
- Air & Space magazine, March 2004
(Page 2 of 3)
In 1990, the Federal Aviation Administration proposed to amend the noise standards and operating rules for future civil supersonic airplanes. After analyzing the comments that this proposal received, the FAA determined that further investigation and research was necessary before a final rule could be developed. Specific noise standards have therefore not been established yet for future civil supersonic airplanes. The FAA anticipates that future proposed standards will require that an airplane's noise impact on a community not exceed that of a civil subsonic airplane certified to the most restrictive current noise levels. Is this feasible?
It may be. In 1999, NASA efforts to develop technologies for a supersonic large transport were terminated after all the manufacturers involved cited the high cost of development and what were anticipated to be stringent federal regulations regarding noise and emissions.
In 2000, the National Research Council conducted a study to identify breakthrough technologies for overcoming key barriers to the development of a commercial supersonic aircraft that would be both environmentally acceptable and economically viable. The study,
"Commercial Supersonic Technology, The Way Ahead," concluded that none of the anticipated obstacles to commercial supersonic aircraft are insurmountable. It went on to note that while NASA should have its eye on supersonic commercial transport, research was also needed to determine the impact of sonic booms produced by smaller supersonic business jets.
The Quiet Supersonic Platform (QSP) program, sponsored by the Defense Advanced Research Projects Agency, began in 2000 and is a Congressionally mandated effort to develop technologies that could reduce the impact of a sonic boom to 0.3-pound-per-square-foot pressure propagated to the ground by the shock wave. This is significantly less than the 2.0 pounds per square foot created by the Concorde, an impact that restricted it from flying at supersonic speeds over land.
Last year, the QSP Program, in conjunction with Gulfstream Aerospace and Raytheon Aircraft Company, demonstrated that aerodynamic shaping of a modified Northrop F-5E fighter reduced the craft's sonic boom signature in flight. The modification consisted, most visibly, of an enlargement to the forward fuselage to make it more bulbous. The test also confirmed that the size of the aircraft has a direct effect on the noise heard on the ground. The QSP demonstration was a success in that it indicated that by simply altering the shape of the fuselage and other aerodynamic elements, designers can dramatically reduce the noise produced when an aircraft exceeds Mach 1.
Even without advanced shapes, the smaller the airplane, the smaller the sonic boom it will create. In fact, the overpressure produced by advanced designs may not be described accurately by the term "sonic boom." Those familiar with the QSP demonstration flights suggest that "sonic whoosh" or "sonic poof" may more accurately convey the sound.
Therefore the development of a quiet supersonic business jet is not only feasible, it is likely.