The flying monkeys got me...

Helis and fixed wing

AMA 957918
IRCHA 4345
AMA Intro Pilot Instructor

Sunday, June 1, 2014

Repairing "Kenny's" MX2

Its mine now...

So Kenny had this Goldwing MX2 that is advertised as capable of being powered by the DLE 30cc gas engine. It can be, but it tore up the wing, around the wing tube, likely due to the flight forces the powerful gas motor put on it. He trashed the internals of the right wing. Since he could replace it, and was moving on from the plane anyway, he said it was mine if I wanted to fix the wing.

I couldn't get great pictures of the damage, but the ribs were broken and cracked for the length of the wing tube. The distal wing was fine. I opened up the bottom and took to it. I shored up the most broken parts knowing they took the most wing load. I wasn't going for pretty. Someone, unbeknownst to Kenny, had made similar repairs to cracks with glue, but no wood. I wanted this thing robust, with a nod to adding too much weight.

Looks pretty...

Big surface cracks with failed and blown out ribs underneath.

Small failures...

Major failures with blow out.

Hard to see but every rib cracked and some with blowouts.

One example of a blown out rib, cleaned up.

Laid popsicle wood down with one splice. It was the same width as the original wood.
Lots of CA. Blue tape keeps CA off cote.

Another set of repairs. Every black dot is where I stuck the pencil used to place the piece of wood inside the balls sheeted parts of the wing. Two major ribs here near the wing root were blown out. You can't see where I buttressed the ribs along the chord of the wing inside. Also, the thick (0.8mm) plywood that makes up that last rib with the screw it it at the wing root was also delaminating (you can see the crack at the "top" of the rib in the pic (its actually the bottom of the wing at about 11 o'clock. At 1 o'clock you can see where the sheeting popped out from behind the rib. Fixed that too.

A shot of that major rib repair. I ran that popsicle stick rib as above then overlaid a 4mm square rod of balsa along both sides of the original rib, running under the edge of the popsicle stick (which runs along the actual top of the wing). This is where the major loading occurred. That round hole is the end of the wing tube, so this is where its cantilever forces end and the wing can flex. Will run one piece of wood in an X between these two ribs to support against that flex.

I added some epoxy to the major joints, but the joints and supports I added are CA's into place. Will see if I can get some of this green cote at the LHS tomorrow. Final pics to follow. 

I just bought Kenny's 30cc Sbach from him, so it will be awhile before I get the electronics for the MX2 to rebuild it as an electric, but she will be awesome. I am pretty sure she will be Aidan's second plane!

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