The guy has probably forgotten by now, but...

"Morgans" wrote in message
...
A colleague and I were discussing a plane that has been practicing
aerobatics near his house, and all the noise it was making. I started
into
telling him how the prop was making most of the noise, and he seemed to
think I was crazy for thinking that.

I think I will have to show him something written, to believe me. Anyone
know of a website that compares prop noise and engine noise, especially
when
it comes to high performance and constant speed props?

I took part in a noise study some time back. A church located about a block
off (and in line with) the SW end of 06/24 was going to expand and they
planned on including enough soundrproofing to keep the sunday morning
services hearable by those attending.

The study was done off the other end of the runway as there is a shopping
center parking lot and an auto dealership just to the south of the climbout
path. Most of the high performance planes are just reaching pattern
altitude at that point.

A 210 created the highest noise level at 90 db with me a bit behind him. On
one take off I didn't get the prop RPM back quite as soon as I did on the
other take offs. The Deb was measured at 93 db, or twice as loud as the
210. The only difference was the RPM. Coming back on the MP made no
difference.

The main difference was at the higher RPM the two blade prop tips were
supersonic.


--
Roger Halstead (K8RI, EN73 & ARRL Life Member)
N833R, World's Oldest Debonair? (S# CD-2)
www.rogerhalstead.com


By the way I have googled til I can't read anymore!
--
Jim in NC