baggage bulkhead

[svyolo]

I had a nice bulkhead made for the cargo bulkhead. Nice and light but I didn't like that I couldn't get behind it without emptying the cargo area. In the back of the shop I had a piece of 6 oz kevlar that I had laminated for a different reason, and didn't use it.

I will probably have snaps holding it in a few places, mostly screws and nut plates that are already installed. Maybe 1 or 2 4 inch round clear plastic windows (or just holes) so I can stick a flashlight in to look behind for a quick inspection.

I haven't spray painted it yet. But it is just under 7 oz. Pretty much impenetrable. A full pound less than .016 AL. I think the cheapest pound I saved because Kevlar is slightly cheaper than AL.

[BravoGolf]

very nicely done. Building light takes effort to search out each opportunity.

[Nev]

I had a nice bulkhead too, made from .025 aluminium. I ruined it after bead rolling it - didn’t realise that bead rolling warped the sheet. I’ve now made one from corflute, which seems surprisingly strong and very very light. Not sure if I’ll keep it or revert to aluminium.



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[svyolo]

I think a single layer of fiberglass would be OK as well. CF is a little fragile.

[whee]

AL is noisy. A composite one would be nice. That Kevlar one sounds interesting. Mine is canvas and was supposed to be temporary, I’ll probably never replace it.

[svyolo]

Canvas is probably just as good. Mine was going to be rigid until I put another storage tube in the lower left side for tools/water. I would have to remove everything to rotate the hinged door. I thought a net or fabric would allow me to pull back the lower left corner. Then I saw the rolled up Kevlar sheet in the corner of my shop. As long as it keeps stuff out of where you don't want it, and allows access to where you want, it is good enough.

And the cheapest pound of weight I ever saved. A pound that will never be carried for the life of the airframe.

[stinger]

Just keep safety in mind. I once put a small tool box in the back baggage area of a light plane with out proper tie downs, as I took off in rough weather the box shift aft and I felt the pitch change thinking of the thin plastic partition preventing the box from sliding farther back keeping me from a very bad day ! Stinger

[svyolo]

Kevlar pretty much cannot be torn. Once coated in epoxy, a thin layer, but only one thin layer can be cut with a very sharp knife or very sharp scissors. Without the epoxy, the only way to cut it is with special scissors. It is really tough stuff, even one thin layer. That is probably its' only claim to fame. It isn't much good for anything else.

[Pbruce]

If you do wish to cut Kevlar before laminating, there are special shears which are of course, very expensive. You can also take a modestly priced pair of kitchen scissors and file the cutting edges to 90 degrees. This will do the job. In my model sailplane days I found Kevlar a little disappointing because as Svyolo mentioned, it will shear quite readily once it’s cured into a laminate. It does not share the excellent stiffness properties of carbon.

[SimonNicholson]

I made mine out of canvas. Both for light weight and easy access for a baggage extension for skis/fishing rods etc.

[Nev]

Looks good Simon. Have you used regular domes to attach it? Did you use a stiffener to keep its shape in the corners? Good article in Sport Flying btw !

[rodsmith]

That turned out really nice, where did you find the canvas?

[SimonNicholson]

I stopped by an upholsterer and he had the canvas. Near perfect colour match too. I thought I would have to stiffen the corners, but the canvas is stiff enough. Yes they are attached with standard domes. I still have to run some bias tape around the edge.

[nichzimmerman]

Adding another data point here. I made a frame for the bulkhead out of pieces of .020 with a bent edge, and then covered it in Oratex. Overall its lighter than a sheet of .020 aluminum and doesn't drum. And nothing is going through that oratex. After building the bulkhead I finished covering the baggage compartment interrior.

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[Battson]

Weight please?

[svyolo]

I hadn't thought of that. Good idea.

[nichzimmerman]

Weight is 14.8 oz, and I calculate an equivalent size (21"×28") .020 aluminum to be 18.8 oz.

[Battson]

Ours is two layers of bare fibreglass, which was only 50% the weight of aluminium. Then we added paint, it looks much better but the weight increase was significant.

[nichzimmerman]

I inserted the weight of mine as a comment to my post, but will add it here for those who dont see comments. Weight is 14.8 oz, and I calculate an equivalent size (21"×28") .020 to be 18.8 oz.