firewall insulation

[DanH]

Originally Posted by tgmillso

Do you know where this 3M Nextel 312 can be sourced? Anyone know anything further on this Insulfrax?

Nope. Both are poor practical choices for engine-side firewall insulation.

[tgmillso]

Hi Dan,
I've now worked out why you think 3M Nextel 312 is a bad "practical" choice for a firewall product. It's because for 1/16" cloth in a 30" width it is $140 per linear foot!!! Ouch. That really makes fiberfrax look cheap at $7.50 per foot for a 24" width of the same thickness. I guess that's the downside of using a product that normally spends it's time stopping asteroids from ramming into spacecraft (at least per the data sheet). The larger fiber diameter of Nextel and and lack of carcinogenic status was sure attractive compared to Fiberfrax, but it looks like I'm going to have to don the mask and hack into the Fiberfrax instead.
Tom.

[Dustyone]

Hi Tom,

Very happy with the Fibrefrax :

I installed the firewall doubler on my RV-10 using .016 stainless sheet and Fiberfrax.
Making the stainless box around the control cables was not difficult but stainless does not bend as easy as the materials we are used to working with.

The stainless/Fiberfrax sandwich used on the firewall and the tunnel ,along with the stainless heater boxes has resulted a very cool to touch tunnel and very little radiated heat at my feet.

My aircraft has a very effective A/C unit installed from Airflow-Systems and the low cabin heat from the firewall area was one of my goals.

I am very happy with how it looks and performs .

I used 1/8" Fiberfrax and Type 301 1/42b .016" Stainless Sheet. Thinner sheet would of been better,but it was all that was readily available to me at the time.

3M Fire Barrier 2000 was used to fill in any gaps.

The Eyeball fittings are available from Aircraft Spruce.

http://www.aircraftspruce.com/search...ITTING&x=0&y=0


Very happy with the smooth and maintenance free finish on the inside and out of the firewall.

I was inspired while I was building by Deems Davis (RV-10 ) and Dan H's though testing on his burn rig.

In-flight testing with my insulated firewall,showed that the hottest spots on the firewall are now the engine frame mounting bolts.
There is still an elevated temp area around the closed heat boxes so a diverted valve up stream of the heat boxes would help.

With two summers of North Australian flying,the cabin temps have been very comfy with the A/C consistently being able to have a 10 deg C drop at the vents over outside ambient temps. ( Happy wife = Happy life )

https://goo.gl/photos/Lo9W1kiobwgEUCr5A

The FLIR camera is an attachment to the iphone from,
http://www.flir.com.hk/flirone/content/?id=62910

Very useful for finding failed insulation points and confirming where the heat flows around an aircraft.

Thank you to all that post their collective knowledge on this site to pass on to the next builder.

I'll be visiting Oshkosh for the first time this year and hope to meet many of you that are on these forums.


https://photos.google.com/share/AF1Q...JyTlp0UUxFVnN3

Cheers,

[Greenley]

What thickness of Fibrefrax are people using, 1/16 or 1/8? I have been searching but can't seem to find a reference.

[Ron B.]

I used 1/8".

[tgmillso]

Hi Ashley, thanks for your comprehensive overview. My fiberfrax arrived in Tas yesterday, so I'll be at it shortly.
Bill. 1/16" seems to the the general norm for the belly fiberfrax thickness, then covering with 5 thou 16" wide titanium sheet (from Titanium Goat) or stainless steel, and as Ron said, 1/8" for the firewall, followed by a covering of 0.002" stainless foil. I'm a little hesitant about using titanium 5 thou sheet on the firewall even though the weights will be similar as titanium is almost exactly half the density, because if you need to add a hole through the firewall in the future it is easier to punch a hole through the 0.002" foil with successive pokes with a knife. Cutting 5 thou titanium in place could be a bit of a dog, unless someone else could offer up an alternate experience with this?

Tom.

[chaskuss]

[quote=Dustyone;1077774]Hi Tom,

snipped
The Eyeball fittings are available from Aircraft Spruce.

http://www.aircraftspruce.com/catalo...ickkey=3026635

snipped

Ashley,
No joy on the web link you provided above. I found the two links below. First is a SS plate with a steel ball. See

http://www.aircraftspruce.com/catalo...lickkey=268034

Less desirable from a fire protection stand point would be the units below, which have an aluminum ball. See

http://www.aircraftspruce.com/catalo...lickkey=268034

Which did you use?

Charlie

[David Paule]

Originally Posted by tgmillso

....I'm a little hesitant about using titanium 5 thou sheet on the firewall even though the weights will be similar as titanium is almost exactly half the density, because if you need to add a hole through the firewall in the future it is easier to punch a hole through the 0.002" foil with successive pokes with a knife. Cutting 5 thou titanium in place could be a bit of a dog, unless someone else could offer up an alternate experience with this?....

You can drill a hole easily enough in the .005 Ti foil, but in my limited experience it's somewhat difficult to get it smooth and without a burr. Perhaps I just haven't found the secret sauce. I prefer using a Whitney Roper punch but that's limited to size and location.

I just tried using an X-Acto knife to puncture some .005 Ti foil and was not successful. Haven't tried a real knife with a sturdy blade, though.

I plan to use the .005 Ti foil on my firewall but will use .020 Ti for the belly, where it'll be the primary fire barrier since the aluminum floor won't work for that. According to the FAA, .016 is the minimum thickness for a titanium firewall. I'll have the Fiberfrax between the belly Ti and the belly aluminum floor.

Dave

[tgmillso]

Hi Dave,

Thanks for the feedback on the titanium drilling. With respect to the belly skin in mind that Dan Horton's testing has shown that 0.002" stainless foil backed with fiberfrax can successfully meet the 2000 degree flame requirement, so going to 20 thou is pretty significant overkill. The most important thing is the layer insulation before your airframe structure so that you don't simply transfer the heat from one layer of metal to the next (and then to your carpet/paint/feet etc). Take a look at this post for further details on a 0.005" belly skinning. I'm not far away from doing mine, and will use monel MK319-BS rivets in the middle (sealed with 3M Fire Barrier), and simple AN426 rivets around the perimeter where heat is less of an issue. This will allow me to keep everything flush and make cleaning the belly easier.
http://www.vansairforce.com/communit....php?p=1063167

Tom.

[Dustyone]

Hi Charlie,

I used the SS Pressure Plate with the steel pass through.

http://www.aircraftspruce.com/catalo...lickkey=268034

Cheers,

Ashley