Fin Repair

[Crazyrocket]

Well, my 2.1 AMRAAM that I used for my first L1 cert was found a year later. However, in its fight with a combine, it lost a couple of fins (appears to be the only damage). I am going to get it back at the next MDRA launch. In talking with the person who found it, the lower G10 fins broke at the OD of the tube and there is still G10 in the slot adhered to the motor mount. Any suggestions in get these parts out without total destroying the rocket? I guess I could remove the bottom CR with a dremel and then try to get the remaining fin tab out.

If I cannot repair, at least I got my 29/180 casing back. And since I bought another one to replace it, you know what that means...CLUSTER time.

 

[Karl]

Same thing happened to my rocket called 'Finally Ready'. 4" Rocket, 8ft long.
Pic is here.

I used a dremel to cut the remainder of the fin off, and used the drum sander bit to remove the paint around the fillet for a new fillet to grab onto.

I cut a new fin out of 3mm G10 (The rest of the fins were this too) and roughed the G10 up as usual, where the fillet would touch.

In addition to that, I drilled 3mm holes all the way along the bodytube around where the fillet would be, and down the fin too. I believe people call these as 'Glue Rivets'?

Then I surface mounted the fin using a nice wide JBWeld fillet.


You can see from this picture that the plain G10 fin on the underside of the booster is still intact from coming in ballistic from 1000ft. And thats just surface mounted. It just had a little crack running around the fillet. The JBWeld really held up to its expectations!

 

[Crazyrocket]

I thought about surface mounting, but I am a little hesitant since it would be surface mounted to quantum tubing. I may be able to dremel some of the fin tab from the outside and then epoxy and fillet. It might give it a little more strength.

 

[Reed Goodwin]

A similar thing hapened to me back in April. My rocket landed without a main chute and snapped the 0.062" G10 fin clean off:https://community.webshots.com/photo/283375704/330296567tIgqAV. Later I tried to get the rest of the fin out with my Dremel and a cutoff wheel. One of the problems I ran into while grinding away was that it was very difficult to tell where the fin ended and the Quantum tube began so the fin slot got a bit wider. The work proved too time-consuming with little result, so I ended up building a new fincan. With the new fincan I made some changes so hopefully the rocket would fare a bit better next time around. I know that probably doesn't help you much, but at least you know that a Dremel and a cutoff wheel will remove the G10.
Reed