Grave Danger Fin Repair

[doug_kosty]

So... my Grave Danger had a bit of a rough landing and snapped off the tip of one fin. The fins are 1/8 inch plywood, TTW, and have my best fillets on them. Sigh.

I have fashioned a replacement bit and glued it on - am currently in the process of sanding it to blend into the original fin better.

I am left with the thought that this will probably snap off on the first landing so I am wondering what would be a good reinforcement method? A layer of really light fiberglass? Paper ? Do just this one fin or all three?

Ideas are welcome. I don't want to add this one to the junk pile since I really like the look if it and the lettering by Stickershock turned out great....

 

[El Cheapo]

Forget the repair and trim the rest to match the busted fin.

 

[pokerace721]

skin the fin with paper...as far as trimming that would work, but can you post a picture of the damage fin? How much of it broke off.

I was considering a Mercury kit...what are the components like? Are they good quality?

 

[El Cheapo]

The Grave Danger Is a nice kit. I've even seen someone do an L1 Cert on one.

 

[pokerace721]

I like the RDR 1 and 2 kits...short fattys.

 

[qquake2k]

I was considering a Mercury kit...what are the components like? Are they good quality?

I absolutely love my Mercury Hijacker. Great kit. I can't believe all you get for $40: ejection baffle, TTW plywood fins, nylon parachute, 29mm motor mount. I've flown mine on up to G80's. The only damage so far was a small zipper, caused by the Kevlar cord I used. I just put a wrap of foil tape around the top of the body tube to cover the zipper, and it's still flying.

 

[qquake2k]

So... my Grave Danger had a bit of a rough landing and snapped off the tip of one fin. The fins are 1/8 inch plywood, TTW, and have my best fillets on them. Sigh.

I have fashioned a replacement bit and glued it on - am currently in the process of sanding it to blend into the original fin better.

I am left with the thought that this will probably snap off on the first landing so I am wondering what would be a good reinforcement method? A layer of really light fiberglass? Paper ? Do just this one fin or all three?

Ideas are welcome. I don't want to add this one to the junk pile since I really like the look if it and the lettering by Stickershock turned out great....

I don't quite know how to describe this, but you could cut matching slots in the broken fin and the repair piece, epoxy strips of plywood or 1/8" hardwood dowel in the slots, and sand it flush. Kind of like tenons.

 

[qquake2k]

I used some pieces of cardboard and paper to illustrate what I mean. You could also cut a dovetail in the fin and make it like a matching puzzle piece.

 

[doug_kosty]

To answer a few questions -

1) The part that broke off is about 2 X 2 cm. If I trimmed the fins to match, the resulting fin would be really prone to breakage.

2) I really liked the build in this kit - went together well and other than this incident has been a fine performer. It even spent more than an hour floating in Mission Bay and was recovered by a jetski without any damage. That may be more a testament to the many layers of paint and primer than the actual quality of the kit.

3) The tenon or dovetail idea is clever. I'll give that a try on the next break...

4) I'm thinking that papering that fin will be adequate. Heck - the vinyl will probably also lend some strength

 

[El Cheapo]

Lots of good info, qquake. Must hage been a slow day in North Calaki-laki.

 

[qquake2k]

Lots of good info, qquake. Must hage been a slow day in North Calaki-laki.

Kinda slow. LOL

I just like finding solutions. And coming from a woodworking background, tenons and dovetails were a natural. I've seen picture frames put together with the "tenon" method.

 

[pokerace721]

Kinda slow. LOL

I just like finding solutions. And coming from a woodworking background, tenons and dovetails were a natural. I've seen picture frames put together with the "tenon" method.

qquake I think your ideas are really unique and feel they would work good. Might be worth trying sometime.

 

[AlfaBrewer]

The Scortch kit from Red River Rocketry actually uses the dovetail idea to assemble the fins (forward cant). I haven't put the kit together yet, but it's next on the build pile.