Quote:
Originally Posted by freebeard
I don't have a handy reference, but isn't air basically incompressible until you reach transonic speeds?
Also—supercavitating torpedoes and shark skin.
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*Yes,air is considered an incompressible fluid at 'low' speed.
*The supercavitating torpedo is riding within a shroud of gas surrounding the body,created by a portion of the rocket's flow,directed forward to discharge nozzles in the nose.It essentially never touches the water.
*The shark skin has water sequestered within the surface matrix,and the outer flow is 'rubbing' against water,rather than a solid surface.
*Penguins carry air,embedded within their feathers to isolate a portion of their surface area from the water.Gentoos are the fastest,with a frontal area based Cd 0.07.
*Russian ice breakers have 'bubblers' which 'lubricate' the interface between the hull and ocean water.Like the Squall rocket-torpedo.