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Felt as baffles?

Kalibr

Well Known Member
I read Dr. Anders’ article in the Kitplanes magazine where he is describing sealing the cowling gap around the prop extension with a felt gasket. I am wondering why felt is not commonly used as a baffle material. I seem to recall reading an older article where felt is mentioned as baffling material, but not recently. It would seem to comply to the curves well, seal well, be gentle on the cowling underside, shouldn’t be heavier than the traditional rubber/silicone material. Judging by Dr. Anders’ usage in his application, it seems to be plenty durable.
The possible negatives I can think of are a) possibly absorbing oil and stuff in the engine compartment (not sure if it’s a concern though) and (b) flammability (although natural wool is fairly fire resistant and doesn’t emit poisonous gases, especially compared to non-silicone rubber baffle material commonly used.
What am I missing?
 
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My Stinson had felt as the baffle seal.

Compresses and sags when it gets old or oily.
 
Close!

Please call him Dr. Anders - he was a practicing dentist - could still be? A good fella to have in your corner for sure.

Yes - you can use the wool as baffling in tight spaces where the rubber does not obey your commands. I would think the 1/4" stuff might work - maybe 3/8" would be longer lasting? The wool will likely wear out a bit faster, but it's easy to work with if replacing worn pieces.

Use silicon where possible - it lasts almost forever when done correctly.

The wool does not hold it's dimensions very well - it might stretch out if you don't use a strip of aluminum or similar to hold it to the metal baffles.

BTW the sealing of the prop shaft is a real deal. I have seen many different methods of forming the seal - send in a pic of your design!
 
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