Ross Kean

Sorry, no pics

I dumb-thumbed my kit-built Seamaster into the drink. The wing fared quite well - pulled the hold-down bolts through the wing and broke the 1/4" dowels. The covering was in ribbons but everything was still structurally sound.

For the most part, the fuselage survived from the front almost to the tail. The tail, however broke off completely. I noticed that the break was right across one of the "lightening" holes at the back of the fuselage. There was no more than 1/4" or so of light ply (above and below) the holes. Not much wonder that it broke there.

I think I can glue the tail back on and redo some of the covering but even if I can get it as strong as it was originally, I don't think this is good enough. Anyone have any ideas as to how this weak structure could be strengthened without adding a lot of excess weight?

It's a great flying plane and is worth the effort to fix!

Ross

JimCasey

My Feedback: (1)

Glue it back in place, and lay in a lite-ply doubler inside the fuselage bridging the fracture in each part. I would probably make it 2" long x 1/4 wide, but it'll be as strong as it can get if you make it long enough to go past the lightening hole edge on each end. Be sure you clean up the inside of the fuselage first so the patch lays flat and not on top of splintered wood or glue blobs.....

Polyurethane adhesive (gorilla glue, Pro-bond) is much lighter than epoxy,waterproof, and it expands and fills voids in the joint as it cures. Clamp it in place with clothespins while it hardens.
Cure time depends on temperature and relative humidity. Here in Florida right now we have to work fast with it. In the winter, (60F, 30% RH) it takes a coupla' hours.

Ross Kean

Thanks Jim

Light ply doublers are along the lines I was considering. I think the repair could be at least as strong as the original. I was also considering using some of the canned expanding polyurethane foam (used for insulation). The stuff sticks like crazy and is fairly strong when fully cured. I may have to try some and see if it is too heavy. One thing that a Seamaster DOES NOT need is more weight at the tail that would have to be balanced by nose weight.

Ross

JimCasey

My Feedback: (1)

Use the glue. The foam is strong enough to glue itself in place but the actual glue is REALLY strong.

BillHarris

> The foam is strong enough to glue itself in place...

Yes. And one of the positive features of the poly-u glue is that as it expands, it penetrates the foam making a much stronger joint by increasing the glue area.

On repair doublers, I've had good results using 1/32" ply instead of lite-ply, especially if the doubler has to have a large area.

"YMMV"

--Bill

davcoz

My Feedback: (17)

I was flying my Seamaster this past Sunday. It's an arf with a saito .56. In order to land it I have to fly it between two trees, bank it hard to the right and come in. That's usually no problem. This time I was coming in and I noticed a boat in the vicinity of my flight path. I took my eyes off the plane for a second to make sure I wasn't flying over the boat and one of the trees jumped out and grabbed the wing. The plane nosed down into the water from about twenty feet. The only damage I had was a small dent in the leading edge of the right wing. THAT WAS IT!!!!!

After I poked some small holes in the covering over the dent I use wind ex and my iron to steam out the dent. Just to be safe I reinforced the wing hold downs with tri-stock and epoxy. I dried out the engine and ran a tank of fuel through it, rechecked my CG and all is fine.

WHAT A PLANE!