diy floor/padding/insulation ideas?
 

For those interior diy'ers... what did you use for the floors?

I have no other interior niceties other than seats. I would like to install some sort of floor system that includes insulation/padding to fill the space between the floor stiffeners. I would like to mount that insulation to a thin piece of something: aluminum, plywood, fiberglass, carbon fiber, ?, etc. I'm not sure about carpeting it or not. The goal would be to have a floor that is not the skin of the fuselage and provide some sound dampening.

I would like to have a separate piece for both the pilot and passenger sides that can easily be lifted out without removing screws. I also don't want something that can slide and bunch up at the rudder pedals either. And I'm not worried about covering the center fuel pump section yet.

fire retardant, non toxic smoke generating materials would be important.

So, what have others done? what worked well, or what would you have done differently.

Thanks,

Balsa
 

I put balsa wood between the ribs and then an aluminum floor on top. The carpet is gel tied in place. I put fiber frax under carpet for fire proofing.

The best approach is to insulate the outside of the airplane first. Try 1/16" fiberfrax felt under a 0.005" stainless steel panel attached to the belly, as wide as the cowl outlet and extending about 2 feet rearward. Extend the leading edge into the engine compartment and curl it up to attach to the firewall, so the exit has a nice radius at the firewall corner.

Unsized batts of ceramic refractory fiber (kaowool or similar) don't smoke when heated. It's darn near the only material that doesn't, and would insulate nicely between the aluminum skin and an aluminum floor. Loose fibers are a possible cancer risk, so it would need to be sealed away. The same material is available in rigid board form, which might work well when cut to fit between the stringers. However, be aware that it will smoke when heated, due to the adhesive matrix which holds the fibers in rigid board form. Same is true for fiberfrax felt, BTW. It smokes when heated as the adhesive burns away. With any of these materials, the inner floor would need to be well sealed around the perimeter to keep airborne fibers and smoke out of the cockpit.

Bugsy's balsa wood idea is interesting. Stiff, light, and a good insulator, but I would definitely install the fiberfrax/stainless panel on the outside. Fiberfrax under the carpet as "fireproofing" is like wearing your raincoat inside your underpants. And as as noted (again), it smokes. Don't use it inside the cockpit.

A really trick removable floor panel? Aluminum with a bonded aluminum honeycomb sandwich on the underside.

Bare aluminum floor is wonderful; lightweight, easy to clean, wears like, well, aluminum. Ever notice how we get carpet in our cars, then cover the carpet with floor mats so it doesn't turn into a mess?

Then we install carpet in our airplanes.

The gods must be crazy....;)

Where would you buy this and is it already bonded?
If not, how would you bond the aluminum to the honeycomb?

How hot does the floor get with no insulation? I am sure that there are a lot of RVs flying with out having insulation on the outside under the floor.

Jeff,
For the price of approximately 73 gallons of avgas Classic Aero has a nice floor solution. Take it unless you like to do it yourself. Once in a while I remove the carpet for cleaning or drying ( I am parked under the elements) I can't stand the floor vibration for couple hours. I fly an RV9 the similar fuselage to yours. Luke and Co. did a great job designing that dampening sandwich. You will love it. Just sit on the ground half a day to afford it. :D

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?

I used some ACS 3/4" soundproofing black foam material (I don't recall what it is called but comes in various thicknesses - not fireproof at all). Over that I laid a piece of 0.040 aluminum on each side of the cockpit (one for pilot, one for passenger). I was able to cut and fit the aluminum so that it stays in place by bending a flange on the center portion where it abuts the longeron, and the other side slides under the longeron on the side of the airplane. Pops in and out easily. On top of the aluminum piece, I glued some skateboard material for friction so my feet don't slide around on the aluminum.

Has worked well for me for 8 years.

Need a base plate (3/4" birch plywood, a 1/2" aluminum plate, whatever you have handy), a plastic sheet, some sealant tape, and a vacuum pump and fittings. Lay the bottom aluminum sheet on the plate, spread thin layer of a suitable adhesive (perhaps Hysol 9430), add honeycomb, and bag it to the plate for cure. Flip and repeat for the top sheet, which will be the actual cockpit floor.

The first sheet can be very thin. If the floor stringers are 3/4", use a 1/2" honeycomb, which will result in 1/4" air space between the thin face sheet and the outer skin.

Here's a gear door bagged on a base plate in my shop. Foam core with top plies, but the setup is the same.

Here Greg knows the risk. If the belly skin melts (as it has been shown to do given an fuel-fed engine fire in flight), or even gets very hot, that black foam will ignite, and when it does it's really awful. The saving feature is the aluminum cabin floor overlay, which should isolate the burning foam to some degree. I'd still bet on a very serious smoke problem.

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.

Let's be really careful about insulation in the cockpit, ok?