Is it possible for a propeller-driven plane to fly faster than the speed of sound?
by 
Charles Varvaro
ANSWERS: 3
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There have been cases of high-performance propeller planes coming apart during full throttle dives. Speculation is that they may have reached the speed of sound and the stresses of the trans-sonic aero loads caused the airplanes to come apart. No propeller driven plane I have heard of has been designed to survive trans-sonic aerodynamic loads. This speculation seems plausible to me, so I would say that it is possible, and may have been done in a few cases, if only momentarily. I would also caution that even if it is possible to design a plane for these conditions, it probably requires gravity assist since the efficiency of the propeller typically drops as more of the propeller is moving supersonic. If there was a supersonic engineering solution out there that would be more efficient than a turbojet, somebody would be building it. Thanks for the question, it has me thinking... we can design water propellers for super-cavitating conditions, could we design a prop for high-supersonic efficiency? (I doubt it... they probably call it a turbojet.)
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The propeller is the limiting factor as jets can exceed the speed of sound without their wings and fuselages breaking apart. Propellers that can withstand sonic shock are not efficient enough to drive a plane at supersonic speeds. A great example of the problems with a propeller driven plane trying to go faster than the speed of sound is the XF84H, the world's loudest aircraft. The F84 was an early jet fighter. Early jets had high top speeds, but they were slow to accellerate. The experimental version had two jet engines driving a propeller through a shaft in an effort to attain jet-like speeds and propeller-like accelleration. It was a complete failure. See www.aviationtrivia.homestead.com/XF_84_H.html
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Unfortunately probably not - at least not under propellor power. The physics involved with propellors basically forbid it. In regard to the comment about old warbirds disintegrating - the only reason for this is that the whole plane was not designed for supersonic flight. You could build an airframe that could handle mach 3, but the propellor just physically would not pull it past mach 1. In fact, the wings on a Spitfire would have been quite efficient for low supersonic speed. The rest of the plane wouldn't have handled it though. With the difficulty involved in trying to design a propellor that would allow supersonic flight, it's easier and cheaper just to go to a jet.
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