How do I repair my EPO foam Mig-15 wing? - RC Groups
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Jul 15, 2012, 08:53 PM
Remy130's Avatar

How do I repair my EPO foam Mig-15 wing?

Hi guys

Took my planes out for a spin today before some thunderstorms took over.
A bit gusty, 1knot-10knots.

The mini-air was ok, not a stellar plane. will write a separate review.
My first glider type plane, the hawk did ok, but the rudder would not work on the ESC. It flew ok with just ael and elev.

The Mig-15........ I installed Dons Wicked motor in it, that thing is like a monster.
Sadly, the plane took a dive as a gust of wind hit me when it was taking off.

So, HOW do I repair the wing? Simple CA glue, gorilla or both? reinforce it with some carbon rod for the next crash? Cant wait to get this $60 guy back up and see how it actually flies.

Oh, and another newbie mistake, was soldering a Deans on my 1000mah lipo last night, and cut BOTH wires by accident, completing the circuit and shorting out the battery. there was a snap and a smell, so I am assuming the thing is a gonner right? Man, need a shorter wire cutter

Thanks guys
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Jul 16, 2012, 02:16 AM
Vertical Arrival Specialist
clinth01's Avatar
CA should be OK with EPO. I usually use a toothpick and poke lots of little holes in the mating surfaces to get as good a grip as possible across the repair.

If I were you, I would also get some very light fibreglass cloth, cut it into a kind of 'cross' shape, and with thinned epoxy resin use it to both reinforce the underside of the wing across the break, and to toughen up the fuselage underside for belly landings. It should dry a light grey colour, so will be nearly invisible over the silver colour when you're airborne.

As far as the battery goes, I suspect that it might be a gonner. As a newbie, I carefully cut the old connector from a battery, and stripped the insulation from each lead. After admiring the neat job that I had done, I then put it on the bench where it shorted across a screwdriver that was lying there
Last edited by clinth01; Jul 16, 2012 at 02:23 AM.
Jul 16, 2012, 02:33 AM
Remy130's Avatar
Thanks Clinth.

The plane literally flew from my hand, to the ground, wasn't much of an impact as it landed on its wing, it taking the force instead of the fuselage. Which was probably a good thing as lightning was coming in a few seconds away anyways.

I also admire my 'neat' jobs that a blind man could laugh at. But once shrink tubing covers it, who knows right?

Fiberglass cloth, that on HobbyKing?
Jul 16, 2012, 06:41 AM
Vertical Arrival Specialist
clinth01's Avatar
It is, but get the lightest weight that you can - the less weight that you add for the repair, the better. It is mainly to stop the underside of the wing from pulling across the repair joint when you're hauling it through high speed turns.

If you're just starting out, it can often help to get someone else to launch the plane for you until you get it trimmed out ( leaving you with both hands on the transmitter) and are confident that it won't make any 'unexpected manouevres' on launch. Once balanced correctly from the manual, a power-off glide test to check it out is not a bad idea before its' maiden powered flight.
Jul 16, 2012, 03:42 PM
222 km/hr Parkjet flyer
solentlife's Avatar
With greatest respect - if you poke holes and then use CA you actually weaken the joint as CA relies on close fit contact of surfaces .... it is not a gap filling glue unless you buy the specific gap-filler type.
Second that CA itself as a gap filler is a very poor mechanical material.

Personally - I use 5 min epoxy. Two main reasons.

a) It gap fills and bonds into all those nooks and crannies.
b) It gives you time to work and set up the wing straight and aligned.

Epoxy will add weight - but if you are careful and spread thinly where needed - its minimal.
Jul 16, 2012, 06:10 PM
Vertical Arrival Specialist
clinth01's Avatar
You are correct, solentlife. I only use the gap filling type for repairs, as there is almost always small areas of compression and deformation of the foam that you just can't get perfect - I should have been more specific.

And when I said 'poke holes', I didn't mean make it like Swiss cheese

Just enough of a tiny impression to maximise contact area. I have had CA delaminate a few times when repairing very clean breaks in foam.
Jul 17, 2012, 12:58 AM
Remy130's Avatar
Thanks guys.
The local RC shop recommended Gorilla Glue, which is similar to 5 minute expoxy. It expands in time though. I bought a carbon rod, will use it as a wing spar, then epoxy the joints, then CA glue with instant kicker the tip and rear of the wing to bond it so the epoxy wont push the wing away from the fuselage when it dries.
Jul 17, 2012, 02:51 AM
Remy130's Avatar
Well, made 1 inch and 2 inch long cuts in the rod, placed it against the EDF housing and just inside the intake lining. Used a drill bit with my hand to easily make a hole for them.

going to expoxy/gorilla glue them in and CA them in. Then glue the wing on, then use some aluminum tape to seal up the gap.

the LHS guy noted, if you reinforce with spars, then the wing will break off somewhere ELSE! as if the wing/fuselage area IS the preferred break point because its easy to fix.

Hmmm food for thought.

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