24.02.2009, 21:36
Thats not the sound of the prop tips breaking the sound barrier. Its the doppler effect of the engine noise and exhaust noise, combined with the propeller spinning, and the airflow through and around the prop and airframe. All piston engined aircraft make that sound to a greater or lesser extent doing a flyby. The amount of noise will depend primarily on the speed of the aircraft. The noise also changes when you get multiple aircraft or multiple engines with aircraft in formation.
Having the prop tips go supersonic is extremely inefficient, and fighter designers avoided it by putting bigger or more props on the aircraft so that the aircraft could use the full power of the engine.
In the case of the black sheep aircraft, the Corsair had a 14' diameter prop on it to use the power of the engine fully. the Spit XIV used a 5 bladed prop for the same reason.
As an example of an aircraft that does have the prop tips going supersonic, check out youtube clips of the Harvard (or Texan for the americans) like this one http://www.youtube.com/watch?v=8GAx3Xu0Jis at 16/17 secs and 51 and 58 secs. That loud rasping noise is the prop tips breaking the sound barrier and exactly the same as with any other sonic boom, you dont hear it till just after the aircraft has gone past.
Having the prop tips go supersonic is extremely inefficient, and fighter designers avoided it by putting bigger or more props on the aircraft so that the aircraft could use the full power of the engine.
In the case of the black sheep aircraft, the Corsair had a 14' diameter prop on it to use the power of the engine fully. the Spit XIV used a 5 bladed prop for the same reason.
As an example of an aircraft that does have the prop tips going supersonic, check out youtube clips of the Harvard (or Texan for the americans) like this one http://www.youtube.com/watch?v=8GAx3Xu0Jis at 16/17 secs and 51 and 58 secs. That loud rasping noise is the prop tips breaking the sound barrier and exactly the same as with any other sonic boom, you dont hear it till just after the aircraft has gone past.