flyrotary@lancaironline.net Mailing List Archive

Jim; That is the way I fabricated the fuel tank for my Wittman Tailwind. I riveted in the flanged baffles and welded around the outside rivet heads to seal them. The end pieces and baffle (5/8"flange), I formed a 3/8" flange that fit inside the tank sides, this I did on a wooden form of 3/4" high density particle board. Before flanging was done, the ends were beaded with a 1/2" bead diagonal from corner to corner, to stiffen. Then I pressure tested with 2 psi and soapy water, had one minute hole to fix. JohnD

----- Original Message -----

From: James Maher

To: Rotary motors in aircraft

Sent: Friday, December 29, 2006 6:30 PM

Subject: [FlyRotary] Re: Yet another limp home story

Ernest,

I have been considering several ways to build the tank from alum sheet.

I think that I have settled on the following design:

A one piece sheet that starts at the top front and goes down from there to the front bottom,

then back along the frame, then up towards the vert fin, then back to the top front with a flange to weld the sheet at the top front.

This will allow the insertion of flanged baffles just as in the F.G. tank that can be welded in and then flanged end caps can be welded in to seal the tank on the sides.

This method would have one weld along the top front and then around each side plate.

Of coarse there will also be a sump in the bottom of the tank just as I have in the F.G. tank.

I am not going to glass mine in as I don't perceive much of an air load that far back and the T.back is quite stiff with the rounded corners. Larry's is not glassed in.

Also I'll want to strap the fuel tank to the frame to prevent any movement.

I'm not sure how you would be able to include the baffles with your method unless you were not going to attach them to the top, but you have probably already figured it out.

Keep me posted with your results.
Jim

Ernest Christley <echristley@nc.rr.com> wrote:

Jim, I'm definitely going aluminum. I'm working on building a form
right now, in the exact way that you built it for the glass layup.
I'll lay a sheet of metal around it and beat in a 1/4" flange. Another
sheet will wrap up from one side, across the top and down the other, cut
to shape and one long edge weld all the way around. When I layup the
turtleback, I'll set the tank in place, run a fillet of flox around the
weld, then glass the weld in with about 40oz of glass tapes. There will
only be a small amount of volume lost to empty space, and the load path
won't change. I think it's as true to the plans as one can get without
having a glass tank.