Engineering challenges of supersonic transport
high thrust, the engine also needs to provide a wide range of operation speed. As a result, the high
requirements of the engines of supersonic passenger airlines will be expensive.
The fuselage of supersonic aircrafts is also different from subsonic aircrafts in order to reduce wave
drag experienced. The Sears-Haack body is one of the fuselages that experiences the lowest wave drag
at supersonic speed owing to its length. 4 The design of wings is also important for supersonic passenger
aircraft. The wings have to perform enough lift while reducing drag at the same time. The classic
supersonic passenger aircraft the Concorde used the Delta Wing, which is a pair of symmetrical
triangular wings. The design mainly focuses on increasing the lift generated during the flight. The
Concorde’s slender delta wings are able to cope with wide range of speed because of the vortex lift
generated. Its swept wings can generate more lift than conventional wings at high angles of attack, as
they will create vortices that can provide suction and hence lift to the aircraft. This allows the plane to
operate at low speed because the high angle of attack can bring sufficient lift to the aircraft.
Compared to the problem of aerodynamics, pollution and environmental impact will be one of the
biggest concerns of supersonic transport. Compared to military aircraft, commercial aircrafts are more
regulated in terms of the noise pollution. The FAA (Federal Aviation Administration) has restricted the
maximum noise emission by subsonic commercial aircraft during different stage of flight. 5 When an
aircraft reaches the speed of sound, it will create a sonic boom, which is caused by the shock waves
moving along the ground. The sound generated by the boom is about 110 decibels. 6 The noise
generated by supersonic transportation aircraft led in 1973 to an FAA ban.
To solve this problem, NASA and Lockheed Martin have built a low sonic boom aircraft X-59, which
only produces noise at 75 decibels. 7 It minimizes the shock waves generated by making the shape of the
aircraft more streamlined, which means that the shock waves generated will not be combined and lead
to a huge sonic boom. However, the X-59 can only carry one passenger due to its design, making it
unusable at the moment as a commercial aircraft.
The air pollution caused by supersonic transport is also a problem. The fuel consumption of supersonic
passenger aircraft with the same number of passengers is approximately 5 to 7 times as subsonic
4 A. Filippone. Aerodynamic Drag, Bodies of Minimum Wave Drag. https://aerodyn.org/super-drag/. 5 Federal Aviation Administration. Aircraft Noise Levels and Stages. https://www.faa.gov/noise/levels/. 6 NASA. (Jan 25, 2022) Taming the BOOM. https://www.nasa.gov/feature/glenn/2022/taming-the-boom. 7 William Jeffrey Doebler and Jonathan Rathsam (17 May 2019) How loud is X- 59’s shaped sonic boom?
https://asa.scitation.org/doi/pdf/10.1121/2.0001265 .
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