It hasn't been done for good reason. In the 1950s
the U.S. Air Force flight-tested a jet-engine-powered, propeller-driven fighter called the XF-84H, but the "Thunderscreech" proved so monstrously loud that it
actually made people ill. With less power and a much smaller prop, Rose's plane, Renegade, should be quieter --but not much. With four propeller tips, each going
supersonic simultaneously, and a roaring 1,700-hp
engine, "it's going to be mind-bendingly noisy," aerodynamicist Barnaby Wainfan says.