jim mosur wrote:

Hi Paul

I finally got hold of a sound meter to check the readings on my exhaust. I
removed my new gun type muffler that you saw at Osh. and replaced it

with my

old system that basically consisted of 2, 2" dia. pipes dumping into a 5"
sch. 10 SS pipe x 15" long, This 5" pipe contained a internal 2 " dia pipe
perporated with !/2" holes feeding a single 2" dia. exhaust pipe just
pocking out bottom of cowl.
.
Ground Run.

OAT  25F
RPM 5000
POS.   30' to the rear of A/C 107 DB
            30' to the side of A/C 112 DB
            30' to the front of A/C 120 DB   (Prop .?)
Cockpit                                    113 DB

Flying.

Takeoff & climb    4980 RPM     105 D/B
                               5400 RPM     105 D/B
                               5300 RPM     108 D/B
                               4800 RPM     111 D/B  ( strange, must be
resonance)

I have not done readings from the ground with A/C overhead yet, maybe I

will

get this done this week and then take these readings over again with my gun
type system.

Jim Mosur
C-GAPF
RV6 13B

Thanks for the data Jim. I will dig up those DB readings we took at
Tracy's last year
for comparison. Here is a picture of Jim's muffler at OSH for background info.

Paul Lamar

(REPEAT MESSAGE)
Could someone put these numbers in perspective for me?   For example, how
would these DB readings compare to an IO-360 powered RV-6?  -- Mark

 I'll work on it next time I go up to the airport.

Paul Lamar
 
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