I understand. Didn't mean to sound like I was contradicting you.

"Supersonic" props are an interesting thing. Loud prop blades (I've heard plenty of 'em at Osh Kosh ) are actually going supersonic over just small part of the chord. Not the whole blade chord (width from leading edge to trailing edge). It's the fattest part of the blade on the curved side that goes supersonic first. If the whole width of a prop blade went supersonic anywhere along it's length you would see catastrophic failure.