"Morgans" wrote in message
...
[...] Anyone
know of a website that compares prop noise and engine noise, especially
when
it comes to high performance and constant speed props?

I'm not aware of any references off the top of my head.

What I can tell you is that it's not true that the prop is *always* the
largest noise maker. It depends on prop RPM, exhaust design, and engine
power. In cruise flight, often the engine is the noisier of the two, and
something as simple as redirecting the exhaust upwards rather than down as
it usually is can significantly reduce the noise footprint on the ground.

Conversely, during takeoff and climb, the prop is often the noisier, due to
the higher RPM. The engine is louder at high power too, of course, but the
prop tips being so close to supersonic (or even exceeding it in some cases)
far surpass the noise the engine is making.

It just depends. And of course, an airplane being flown in aerobatic
maneuvers is alternately making more noise with the prop AND the engine,
depending on power and RPM setting throughout the maneuvers.

Pete