Thorp Air Command - T18.net

Just throwing this out there -

Since I've had my head close to the cockpit floor in MLM for a year and a bit, I've often wondered if that area of aluminum acts like a drum-skin, transmitting the exhaust noise.

Has anyone done anything in this area? I was thinking of bending up some light angles and riveting them across the floor under the seats to stiffen things up.

Waste of time? Is there a better way? Roxul Plus?

DW

Dick,
That's (or at least should be) .040, already plenty stiff, the sound is not do to the floor being thin but simply sound transmitting through the floor board. You may want to put some (see link below) insulation between the stringer on the floor and then install your carpet (or whatever) over that. That gives you some sound insulation as well as levels off the floor for whatever you put down there.

http://www.aircraftspruce.com/catalog/a ... oofmat.php

_________________
Lee Walton
Houston, TX
N51863,N118LW
KEFD

I used the 3M sound and vibration panels from Spruce...P/N 09-30206 on the floor and the aft deck area. The aft deck and sides (aft of the baggage compt) tend to "vib" and this stuff removes that "rumble." Peel and stick stuff, easy to cut. Bada Bing, Bada Boom !

RB

A waste of weight. Make sure your exhaust pipes are long enough to direct the exhaust away from the bottom of the plane and press on. I put some deadening tape on the part under the seat and all it did is invite corrosion. Get some good headsets and go fly.

_________________
Bob Highley
N711SH
SN 835
KLAL

If my "pipes" were any longer you could play them in the Saint Paddy's day parade !

RB

If you devide the panels up into smaller areas by way of adding stiffeners as you describe, the resonant frequency of the panel(s) will be increased.
For example, you could add one centered stiffener in the bottom skin panel, the resonant frequency of the two smaller areas would be double.
Add stiffeners to make all the areas of different dimension, then the floor would be de-tuned?
I'm just regurgitating what a sound engineer told me......so it's worth what you paid for it.
A thick leaded panel would reduce the noise, and increase your stall speed.
A more elegant solution would be light weight stiffeners to tune out the transmission of exhaust and propeller beats?