diy floor/padding/insulation ideas?

[DanH]

Originally Posted by rockwoodrv9

What about cork for an insulator? I tried to torch through a piece and it worked well with little heat transfer. I can't remember how much smoke there was. Any thoughts about cork?

It's a good insulator, and when it chars, it's pretty good fire protection. Trouble is (again) the smoke in the cockpit. If the floor is really well sealed around the perimeter so the smoke and outgas can't enter the cockpit, it's viable, just like Bugsy's balsa.

On the other hand, fireproofing the exterior of the belly skin so the structure doesn't heat, then using metallic or pure ceramic materials on the inside pretty much guarantees zero problems, no matter what happens.

[jcaplins]

Dan, those are excellent ideas. It's because of what you have written here and in other threads that I haven't put anything in the cockpit area.

Now when I wrote the original question, in my head, "insulation" was more of sound deadening material and floor vibration reduction , rather than heat insulating. But, I do not want the sound deadening material to be a source of toxic smoke. sorry for any confusion.

- I like the simplicity of balsa wood and aluminum.
- cork would be good, but is typically a lot of glue holding it all together and would end up being highly flammable and toxic.
- I wonder if aluminum honeycomb would make the noise in the cockpit worse?
- I like the idea of using ceramic refractory fiber batting; would need to figure of sealing it and still have removable floors.
- Vlad, I have considered the Classic-Aero carpet...but man that is some pricey carpet and foam. Also, I would need some more custom cutouts for antennas which would make it even more expensive. Perhaps all I need is some closed cell foam that's non-toxic.

[rvanstory]

Below is black rubber soundproofing foam (Soundex) on the cabin side of a simulated stainless firewall, with an FAA-standard 25 sq in hot spot on the front side. The hot metal ignites the foam.

Dan Horton,

I am interested in putting some insulation in my fuse for sound deadening. You posted pics with Soundex products. They show 2 different materials on their web site. Is the one you show in your pics and warn about fire the one Soundex says meets the FAR 23:85a/25:856a Part II compliant? Or was it their other product without that listing?

http://www.soundexproducts.com/order.html

Would like to add something, but your post got my attention and I don't want to be foolish here. Would you please give me your advice on what you would use if you wanted to have some sound deadening materials added?

Thank you .

[DanH]

Originally Posted by rvanstory

I am interested in putting some insulation in my fuse for sound deadening. You posted pics with Soundex products. They show 2 different materials on their web site. Is the one you show in your pics and warn about fire the one Soundex says meets the FAR 23:85a/25:856a Part II compliant? Or was it their other product without that listing?

http://www.soundexproducts.com/order.html

Would like to add something, but your post got my attention and I don't want to be foolish here. Would you please give me your advice on what you would use if you wanted to have some sound deadening materials added?

The first question is "Where in your fuselage?"

The cabin firewall and the floor immediately aft of the firewall are high risk areas for ignition of bad insulation choices. Floor panels some distance aft of the firewall, as well as cabin sidewalls, are low risk, as they are unlikely to be heated to a high level in the event of an engine fire.

Part 23/25.856 materials are intended for cabin sidewalls, and are not fireproof. They are fire resistant, meaning they are merely required to self-extinguish within 15 seconds after the ignition source is removed, without dripping too much melted material. The ignition source per the 23/25.853 test standard is very small....Bunsen burner size. Think little Johnny in the bathroom with his daddy's cigarette lighter, or a hot electrical wire.

Part 23/25.856 materials are entirely unsuitable for firewalls and forward floors. An engine fire is not an ignition source that can be removed at will, and the energy level (2000F over 25 sq inches) is much, much higher. In my opinion, there are no 23/25.856 materials suitable for firewall contact. In practical test, some have been absolutely horrifying. No surprise really. Regardless of claims, why would any sensible builder think rubber, plastic, and polyester can be placed in contact with red hot stainless steel, without adverse consequences?

Actual sound deadening is a big subject. There are several possible approaches. The absolute best would be to build a composite airframe, as the vibration decay loss factors for all composite materials are much higher than metals. Damping resonant vibration of panels can also be done with the addition of mass (lowering natural frequency), or stiffening (raising natural frequency), or adding true damping, i.e. turning the vibratory energy into heat. All of these things add weight.

Ever noticed how an airplane can be much louder when operated in a certain engine RPM range? That is resonant vibration; the engine or prop is exciting a panel at its natural frequency, so its vibratory amplitude gets large. If I had such a range and i wanted to run there, I'd try chasing down the offending sound generator (the particular vibrating panel), and deal with it as necessary.

[rvanstory]

The first question is "Where in your fuselage?"

The cabin firewall and the floor immediately aft of the firewall are high risk areas for ignition of bad insulation choices. Floor panels some distance aft of the firewall, as well as cabin sidewalls, are low risk, as they are unlikely to be heated to a high level in the event of an engine fire.

Thanks for info Dan. Do you know of a specific product that would be suitable for firewall and floor next to firewall (fireproof)? Since rebuilding in composite is not an option, would like to know if there is a suitable product out there?

[kentlik]

I use this product to pre-protect clothing for full fire burns on performers clothing. Works very well. If you want to add some protection to a material. That is not to say spray this on a flammable material and hope for the best, but something to consider.

Here I am on fire with Ban Fire on a white cotton dress, I got two burns out of the clothing probably could have done a third easily.



http://www.banfire.net/allproducts.htm

Kent

[DanH]

Originally Posted by rvanstory

Thanks for info Dan. Do you know of a specific product that would be suitable for firewall and floor next to firewall (fireproof)?

Sound insulation on a firewall? No, I'm not aware of a suitable product specific to sound reduction, rather than heat. Why do you think you need one? Even with 20 lbs of insulation, any conceivable sound reduction won't trump ANR or in-ear headsets.

Read this thread...good folks who thought they "needed" various insulation products inside the cabin, and installed very bad choices...cotton fiber, urethane foam, etc.

http://www.vansairforce.com/communit...d.php?t=141016

Bad firewall and floor insulation should be called fire transfer material. It brings an otherwise isolated fire right into the cockpit. Some do so very rapidly.

This from NTSB report LAX99LA063. The actual failure was a loose B-nut on the fuel pump. The airplane was in the pattern, and flown by a well-respected guy.

Factual Information
On December 31, 1998, at 1151 hours Pacific standard time, an experimental Young Harmon Rocket II, N288M, was destroyed following an in-flight fire and hard landing at a private airstrip near Esparto, California. The commercial pilot/owner was operating the airplane under the provisions of 14 CFR Part 91. He and one passenger departed approximately 10 minutes before the mishap. The pilot was in serious condition after suffering burns over 1/3 of his body and succumbed to his injuries over a month after the accident; the passenger sustained minor injuries. Visual meteorological conditions prevailed for the local personal flight and no flight plan had been filed.

The pilot completed one flight and was taking another passenger up for a short flight around the area. On the downwind leg witnesses reported everything looked and sounded normal, and then they heard several pops, which they attributed to the engine being throttled back. One witness asked the other if the airplane was on fire. The flames he thought he observed went away. They dismissed his observation as sun glare and turned away. When they looked at the airplane again on base leg, 2 to 3 feet of bright yellow/orange flame and a trace of black smoke emanated from the cowling. On touchdown the airplane bounced, hit again, then skewed 20 degrees to the left. The left main landing gear collapsed outboard and the right main collapsed underneath the airplane. They gathered fire extinguishers and did not see the airplane come to a stop.

The passenger stated he saw light gray smoke in the cockpit and notified the pilot. The pilot secured the master switch and turned onto the base leg. At this point the passenger did not observe flames or feel any heat. As the airplane turned wings level onto final, thick black smoke that smelled like burning fiberglass or plastic filled the cockpit. After the airplane came to rest, he observed flames around the pilot and felt high heat. He yelled to the pilot to open the canopy, but the pilot responded he could not get it to open. Momentarily, the canopy opened halfway.

As the rescuers arrived, flames were still coming from under the cowling. The front cockpit was so filled with smoke that they could not see if the pilot was still in the airplane. The rescuers helped the rear passenger out, and then noticed the pilot on the side of the runway.

[vernon smith]

Take a look at the AA207 and AA209 products on Page 14. Dan seems well versed in interpreting the various standards and certs

beaerospace.com/products/structures-and-integration/honeycomb-panels/aerometal/

Vern

[kentlik]

For fire retardedness and acoustic qualities:

https://www.atsacoustics.com/item--R...hoC8HUQAvD_BwE

Not sure thickness minimums