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Firewall Foil Advice

rvanstory

Well Known Member
Planning to use Dan H's information to install Fiberfrax on firewall. Seemed really straightforward until ordering supplies on ACS. They don't seem to sell stainless foil in 24" width??? After trying to find an answer on vendors, found MANY options listed on forum and now I'm stuck in analysis paralysis. Need some questions answered to get "unstuck".

1. Thicknesses listed is from .002"-.010". If I want minimum "wrinkling" and a smoother finish, is thicker better?

2. Does outer sheet need to be stainless? Can it be aluminum?

3. What specific vendor and product would you recommend? I found options on McMaster Carr, but thicker (.008-.010) higher grade SS is often limited to narrower (2") sheets.

4. Some have even suggested HD Reynolds wrap. Can you really get by with Reynolds wrap from local store?​

Thanks in advance for help!
 
Ditto.

Randy, glad you asked....just getting into this now. Looking forward to responses.
 
I purchased the 970J 1/8" x 24" Fiberfrax
and also Ordered McCaster Carr 3254K92 for the foil.
That is .002" x 24"

My plan is to have 2 sections cover my firewall with some overlap.
Either a vertical overlap down the middle or horizontal overlap.

I also ordered some SS pop rivets to secure the overlap area to the firewall.

As you can probably tell, I have yet to install this, but is what I've seen a couple of others do, so that's what I went with.
 
An easier potion

https://www.koolmat.com/heat-resistant-products/foil-heat-products-protection/

Order: #04248 ZERO CLEARANCE / PSA

Install on the fwd side of the firewall.
Does a great job of keeping heat off your feet, and there is some noise attenuation. Touching the cowling IMMEDIATELY after shutting down - the cowl is at ambient temp around the exh pipe areas.

Works more or less the same as the Fiberfrax/SS sheet, but this stuff is cut, peel, and stick. Best to add some of their aluminum duct tape too - both products are the stickiest things I have run across - except Gorilla Tape.

The Zero Clearance sheet is about $80 -have a very sharp pair of scissors to cut the stuff.

I have not tried the silicon sheet they recommend for aviation. I could not come up with a glue to hold it on.

PM me if you want a picture of an installation.
 
Thicknesses listed is from .002"-.010". If I want minimum "wrinkling" and a smoother finish, is thicker better?

Yes, but 0.010" is exactly five times heavier, and provides no additional fire resistance.

2. Does outer sheet need to be stainless? Can it be aluminum?

Aluminum will work as a top sheet only if the insulation is intended for comfort purposes during normal operation. It will immediately melt given an engine compartment fire, and fire protection will degrade rapidly from there.

My plan is to have 2 sections cover my firewall with some overlap. Either a vertical overlap down the middle or horizontal overlap.

Make the overlap vertical. Seal it with a high quality aluminum duct tape. The tape will melt given a fire, unsealing the seam, and allowing the outgassing fiberfrax binder to escape into the engine compartment where it is harmless. The vertical seam puts some of the overlap down near the cowl exit, where the heat will be high. The SS overlap will continue to provide fire protection.

Center%20Seam.jpg


Firewall%20Joint%20Caulking%20800w.jpg


https://www.koolmat.com/heat-resistant-products/foil-heat-products-protection/

Install on the fwd side of the firewall.[/B][/I] Does a great job of keeping heat off your feet, and there is some noise attenuation.

I've used this and similar on low and slow airplanes, where my interest is ordinary thermal comfort during normal operations, but not fire protection. It's not going to be very useful given an FAA-standard fire (2000 for 15 minutes, not 12 seconds with a Bunsen burner), but it looks nice and will keep the cockpit cooler.

Kitfox%20firewall.jpg
 
I used this stuff on my Rocket. No overlap required.

https://www.amazon.com/gp/product/B0055BXWPE/ref=ox_sc_saved_title_1?smid=A1Y5XHUEKDZ4IY&psc=1

To Dan's point I took a sample and had a propane torch on it for about 5 minutes to no effect. Other than the foil disintegrating, the fiberglass stayed perfectly intact.

That is what you see on the Kitfox firewall in the previous photo.

Melt point of fiberglass fabric is fairly high (2100F ballpark, IIRC), but the rate of heat transfer will go up dramatically when the aluminum foil cover sheet melts away at about 1100F. The cover foil is both reflector and hot gas barrier.
 
Penetrations

Hey guys, dummy question here. Do you put this on before you make penetrations and install items, or afterward?
 
And how do you handle the penetrations?

Put a spacer under them?

Let them squeeze the Fiberfrax?

Or something else?

Dave
 
I'm using .005 titanium foil from Titanium Goat, an outdoor equipment vendor. It comes in up to 16" widths, and if you need their 20" wide foil, that's .008 inches thick.

It's not hard to work but compared to the thin stainless, there's a weight penalty. Since I've never worked with the thin stainless foil I can't offer a direct comparison.

Dave
 
I made the big cuts first...holes for engine controls, fuel/brake lines, wires, and mounting of the oil cooler. Throttle/prop/mixture cables come thru one hole like many certified birds.

Big holes have flanges I turned out of 304 stainless bar on the lathe, which firesleeve clamps to. Used stainless screws and steel stop nuts to mount those. Insulation is sandwiched in-between the firewall and these flanges.

My Comanche is 57 years old and had the same type of material on the firewall. I learned from it to make everything removable so the insulation can be replaced.
 
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I used .005 SS Shim Stock, 1/8" FiberFrax, 3M Barrier 2000+. No wrinkled tinfoil look like the thinner stuff but some oil canning is to be expected around the areas where you attach items over it. Also a hydraulic punch works great for making nice clean round holes. Ordered everything from McMaster-Carr.

https://lh3.googleusercontent.com/0...N8WQrNNP9vah-5Li-ixC1oM-uWa6gw4c=w800-h450-no

https://lh3.googleusercontent.com/V...FCUYYt9BhvGNgK9RZL808hV9m1EhIfMI=w450-h800-no

https://lh3.googleusercontent.com/Y...f228SuVOh_IJ2FsA5CCrtiIqPJnOxjT=w1608-h904-no

https://lh3.googleusercontent.com/9...XbymSh2SY697_AxtZppYVg__W7ykl3gl=w800-h450-no[/QUOTE]
 
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