"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

Page 81 of Aircraft Systems for Pilots, by Dale de Remer and
published by Jeppesen, has this to say about prop noise:

"...Propellers make a lot of noise - much more noise than does
engine exhaust. Propeller blade noise is transmitted directionally.
Noise is much greater off the tips of the propeller. Visualize
extending the propeller disk to the ground. That's where the noise
will be greatest."

Dan