Baffle material?

[riobison]

On my 12 yr old 9 with an O320 I'm looking at changing out the baffle material along the sides and back of the baffles.

Looking at Vans store there seems to be a few options.

AirSeal Fabric

Should I get the 2" by 12'?

or

the 12"*56" and cut to fit?

Or am I even looking at the right stuff?

Then the best pop rivets?

Thanks

Tim

 

[DanH]

Practically any sort of silicone material can be made to fit and seal better than AirSeal. The issue is the embedded fabric, which can't accommodate stretch or compression.

Extreme example below, a one-piece seal on a circular baffle wall. Start at one end, set a fastener. Stretch the strip just a bit, set another fastener, stretch, set, stretch, etc. The strip will roll inward, because the free edge is shorter than the stretched, fastened edge.

In the same application, a fabric reinforced strip can't be stretched enough. It will stand straight up, and pucker when bent forward on the inside of the cowl. Every pucker forms a leak. We see them routinely even given the very mild curvature of the rear wall on a RV/Lycoming.

Soft aluminum rivets with large diameter heads work fine.
.

 

[fixnflyguy]

What Dan said..

The pure silicone seals are really nice to work with, when I built my -4, I used the fabric embedded rubber material, and it did fairly well, however the cut, trim, notch and process took a lot of time. I ended up with minimal puckers but the -4 cowl is really curvy compared to the -9. Id go with the silicone next time if I ever change mine. With either rubber or silicone, make sure your corners and any odd transitions are "tied" together with either soft rivets or safety wire stitching, then top coated with compatible sealant. It will help maintain conformity and prevent outward blow-out.

 

[David Paule]

I've got an RV-3B, similar cowl to the RV-4, and don't recommend McFarlane's CowlSaver material. I tried it and it was way too stiff for this application. Sure has low friction, though, as advertised.

Bill, that's a great job on the RV-4, by the way. Impressive.

Dave

 

[BH1166]

I replaced mine using the 1/8” version. Little more time initially getting top cowl on, after a month or so, it started taking shape/folding. Seals like a champ. Likely to last a lifetime over thinner, stuff.

https://www.aircraftspruce.com/catalog/appages/siliconecowlseals5.php

 

[riobison]

Thanks guys.

I appears that the general consensus is that the silicone seal will work better.
Conform and seal better with less leakage then anything with the embedded fabric in it?

Tim

 

[Thermos]

I replaced mine using the 1/8” version.

I see that Spruce carries 1/8" and 3/32" material. I'm guessing the thinner stuff would be better for more "curvy" fits, but is there a significant difference between the two for our applications?

I've never been happy with my baffle seals and this thread is pushing me over the edge to redo them.

Dave

 

[David Paule]

My C180 has the silicone material and after about 700 hours, more or less, it's tearing in a couple areas. Still seals, though. Also, it's wearing the metal cowl.

Dave