flymeaway

My Feedback: (6)

I banged up my CA Models 27% Extra this past weekend and need opinions on how to fix it.

The supply clunk came off and caused the motor to quit. I was in a downline at the time so I didn't have the altitude to glide around to lose air speed. Because I had so much air speed I ran out of runway and had to put it down in the bean field off the end of the runway. In doing so the gear was ripped off (easy fix), and the right stab sheared off flush with the fuse. The stab is balsa sheeted foam, glued and glassed in the center, then glued into the fuse, so I'm not sure how to fix this short of trying to find a whole new stab. I know epoxying the broken stab in place wouldn't cut it, so I'd appreciate any ideas.

My first thought was to epoxy the stab back on, then running braces top and bottom from the rudder to the stab on both sides. Not sure if that would hold or not.

Thanks.
Bob

BaldEagel

Drill straight through the whole thing both sides and epoxy in a carbon rod, if you are rearly clever you could convert the stab too removable by using a Phenolic tube to put the carbon rod inside, then use gator adjusters on inidence pins to make the stab adjustable, turn the whole experience into a positive.

Mike

Rcpilot

My Feedback: (78)

I'd do the same thing.

Glue it back on there with gorilla glue. Tape it in place and make sure it's aligned perfectly while the glue sets. This is going to be the most critical step. Make sure you have it aligned perfectly. Foam and sheeted balsa should fit back together like a puzzle. Should be a perfect fit.

Let it dry for a day or maybe 2 days.

I'd buy a couple 1/4" carbon rods about 2" shorter than the stab width from left side to right side. If your stabs are 24" wide--then get a carbon rod about 20--22" wide.

Install one rod in the front 25% of the cord and the other rod in the back half anywhere. It's just like a wing. Most of the stress is right in the thickest part of the airfoil, so thats where you want one of the rods. Maybe use a 3/8" rod for the front and a 1/4" rod for the back half? Depends on how thick your foam cores are. I wouldn't want to drill out ALL of the foam and put in a huge rod--because then your relying on the sheeting to take all the stress. That will fail on the first flight. You want to leave a good bit of foam in there to take the load.

Now get a long drill bit-- 1/4" diameter and drill right through the whole thing from the tip of the right stab all the way through the root of both stabs and out the tip of the left side.

Slather epoxy or gorilla glue on the rods and slide them in. Slide them all the way through and back and forth to make sure you have spread the glue out as much as possible. You want a good bond.

Let the glue set. Of course, wipe off drips and drizzles before it cures. Stuff the holes in the tips of the stabs with balsa or foam plugs. Sand and recover.

I might think about adding some flying wires now. You might want to drill a couple holes in the stabs. From top to bottom. Insert a wood dowel as a hard point. Epoxy it in the foam cores and sand flat with the sheeting. Now you can attach screws or brackets to the stabs on both top and bottom for your flying wires.

Good luck. It's a bit of work, but it's not as bad as it seams. I've done it. Worked fine for 3 more years until I pancaked the entire airframe on a crosswind landing and snapped it into the concrete. DOH!! [sm=lol.gif]

flymeaway

My Feedback: (6)

Thanks guys. The carbon rod idea sounds good - now if I can only drill a hole that long and not destroy the whole stab.

I think I'll add flying wires too - seems that between the carbon rods and the flying wires, the glued on stab half should be fairly strong.

Any ideas on how to drill a hole that long straight? Also, what kind of drill bit would be that long and not chew up the foam? Not sure I can find a brass tube that long. Maybe 3/8" copper tubing? Or..??

The other problem is when I initially glued the two stab halves together, there was the slightest bit of dihedral. I'm not sure if that'll be a factor in drilling the hole or not.

Goes to show you - these things will crash eventually.

BaldEagel

Don't use a drill use a piece of heated piano wire, experiment on a piece of foam to find the right temprature, do not worry if the hole is too big you can use an expanding poly foam glue to take up the difference and glue in the carbon rod at the same time, IMO if you use a decent size carbon rods or tube (lighter and just as strong) you do not need the flying wires, my 2M Extra has only one 3/8" carbon tube inside the manufactures ali tube, this was meant to be a permanently fixed tail but I made it removable, I have had no problem with the tail, Just make sure your alignement is spot on before you start gluing everthing together, if you have diahedral on one side break it off and start again. If you can remove the tailplane from the aircraft and do the whole job on a flat surface, it will be easier in the long run.

Mike