Broken AT Warthog fin

[mwiggins367]

My first flight of my AT Warthog resulted in a broken fin.
The fin broke at the lock tab.

The fin will still go down into the rocket body about 1/4".

Can the rocket be saved? How can I attach the plastic fin to the body?

Thanks

 

[Rocketmaniac]

Yes it can be fixed ....... One word....... epoxy...... try some 5 min epoxy and make some good size fillets........

 

[Hospital_Rocket]

Moderately easy

mke up some 30min epoxy and thicken it with some milled glass. For a warthog fin root, you will need about a teaspoonful. The ideal consistensy will be about that of peanut butter,

Next, drill about six 1/8" holes in the left over tab.

Put a big glop (technical term for "yeah, that looks right") of the epoxy mix on both sides of the tab and a light coat along the slot.

Press the fin down and align it as appropriate. sit the finished assembly with the fin sticking straight up so the epoxy will flow down over the broken tab.

Works for me each time I break one.

A

 

[mwiggins367]

I guess it goes with out saying, that the fins and tube need some
good sanding.

Thanks for the tips.

 

[DynaSoar]

Originally posted by Hospital_Rocket
Moderately easy

mke up some 30min epoxy and thicken it with some milled glass. For a warthog fin root, you will need about a teaspoonful. The ideal consistensy will be about that of peanut butter,

Next, drill about six 1/8" holes in the left over tab.

Put a big glop (technical term for "yeah, that looks right") of the epoxy mix on both sides of the tab and a light coat along the slot.

Press the fin down and align it as appropriate. sit the finished assembly with the fin sticking straight up so the epoxy will flow down over the broken tab.

Works for me each time I break one.

A

Goodness, that's not encouraging. I just had one break due to the motor tube burn-through mentioned elsewhere. Are the Hogs more prone to fin breakage than the others?

I'll do this, plus I'm planning on drilling the fin just above the body line, as well as some in the body along side the slot, and letting the fillet run through them. If this is a common problem, I may just add these rivet-fillets to the others before rather than after.

 

[Hospital_Rocket]

Time consuming, but bulletproof.

I've also had some fair luck as an experiment (on a Mustang) as follows:

this is kinda hard w/o pix

Using JBWeld

1. I fastened a thin 1/32" piece of G10 on either side of the broken fin tab. sorta creates a socket for the piece inside the airframe to fit in.

2. Filled it with JBWeld, and poked it over the piece inside the airframe. I had to slightly widen the slot in the BT.

3. Clamp and allow to cure.

I found this harder than the other idea, But then I like playing with cement.


I do have one other plan I want to try...

JBWeld the edge of the fin tam to the internal broken piece. Once cured, drill a 1/4" hole in the lower CR and fill with 40z 2part foam.

Need to break another rocket first....

 

[xenon]

after you follow the above suggestions, get some two part expanding foam (PML or Giant Leap) and drill some 1/4" holes in the aft centering ring. Mix up the foam and pour it in using a folded piece of paper. It will lock in the other fins so they don't break either.

 

[mwiggins367]

I don't think it is a problem with the Aerotech fins.

The fin broke because of a tangled chute and a hard landing right on the fin.

Thanks for the information.

 

[DynaSoar]

Originally posted by xenon
after you follow the above suggestions, get some two part expanding foam (PML or Giant Leap) and drill some 1/4" holes in the aft centering ring. Mix up the foam and pour it in using a folded piece of paper. It will lock in the other fins so they don't break either.

That might keep them from coming out of the finlocks, but that doesn't seem to be the problem. The problem is snapping them off the tab. Mine broke right at the fin/tube line, the Wart Hog from losing the baffle and recovery gear attachment, the Tomahawk from a way too fast deployment causing the payload section to knock it right off.

 

[Stymye]

even the toughest rocket can be damaged by a too short/long delay... wrong chute for conditions, too much ejection powder or fast hard ground landings.

foam and epoxy are not the solution ..in those cases, just a fix

 

[Rocketmaniac]

Originally posted by stymye
foam and epoxy are not the solution ..in those cases, just a fix

Oh yea, you are correct about that...... foam and epoxy will enable the rocket to fly again, so he can learn about the delays, chute and other things you said........

 

[Habu]

This may be more common than originally suspected.
Another current thread is dealing with a similar problem, if I'm reading correctly.

Anyone ever seen this happen before