Thorp Air Command - T18.net

What is a good type of firewall insulation? Also, I noticed that some put it on outside of the firewall and some put it on the inside of the firewall. Is there any reason to do one over the other?

I found some double sided mylar (with bubble-wrap in between)home insulation from a hardware store (very light). Would this suffice or is there something better? It has a heat rating up to 300F, but does burn if a flame is put to it.

_________________
Dean Cuke
Visalia, California
N772DM
KVIS

Don't put insulation in the engine compartment. It will get oil soaked! You won't like that.

Aircraft Spruce carries many types that are effective and fireproof. You want something good as removing and installing the tank is not a light chore. The higher cost of the good stuff will long be forgotten when the cheap stuff fails and crumbles. I have measured in excess of 150 degrees at the firewall. You want insulation for you and your gas tank, so don't contemplate the "no insulation" option.

Good luck!

_________________
Bob Highley
N711SH
SN 835
KLAL

Thanks Bob & Rich for the input.

@Rich - do you think that insulating the panels and flooring made a big difference? Is it worth the weight penalty?

_________________
Dean Cuke
Visalia, California
N772DM
KVIS

On the firewall...yes. On the floor I think it helps with the exhaust noise. Side panels not sure, but they were such small pieces that I did it anyway. FWIW I also put 3M sound and vibration panels on the inside below the canopy deck and aft on the sides of the fus. where it angles down to the side skins. I did this because when I rode in my first Thorp and you could hear (and see) the skins vibrate in flight with the headsets on. I don't hear that in mine. Weight penalty? The 3M stuff is 4oz. per sq.ft. The "Insulator" I can not remember what it weighed in at, but it was not that much. With all the other do dads I put on the A/C I probably broke even in the weight dept. by using the wood AD prop (13 pounds) and going with the PC-680 battery vs a wet cell. My MT weight is about average for an S-18. I personally would not be concerned about the weight of the insulation, especially if you are going to just do the firewall and floors. If you need help with the math calculating the weight of the stuff there is a guy in Utah that does simple ciphering for Aviators. [:p]

RB

Thanks Rich for your thoughts. I will probably order enough insulation for the extra areas

_________________
Dean Cuke
Visalia, California
N772DM
KVIS

I purchased an adhesive back foam from Aerotex Aircraft Interiors in Tampa (since gone out of business)and insulated the floor,sides and firewall. It does make a difference. Be careful using some of the spray adhesives as they tend to have a corrosion effect on aluminum