>At full power, the propellor tips are not a million miles away from the speed of sound anyway, adding that might take them over, and aerodynmically, that is a bad thing.
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Surely there ARE some 'planes (current and legacy) where the prop-tips do exceed the speed of sound. How does that relate to the comment that it is a bad thing?
I agree that the use of nitrous oxide in a/c would not be a sensible idea. Many of the car engines go bang anyway. Russian Roulette springs to mind . . .
Spitfires (and many others) had an 'emergency' setting with extra supercharger boost (though not for take-off).