IΒ*had a SIG 4*120 ARF, after a few flights I noticed the wings flapping, and found that the spars were loose inside the wings, and stripped the covering off, squeezed them in position and reglued them all, using CA and Titebond, then recovered them. They appeared to be sturdy with no more flex in them, so today IΒ*flew it. Had it up for 15 minutes, gentle turns, no hotdogging, a few loops some rolls mostly half throttle flying, landed, checked the wings and they still appeared to be tight, no flex detected.Β* IΒ*put my Kadet up for a test flight after doing the repairs fom when I had a mishap with a strong cross wind that took me by surprise that flipped it on landing and broke it in half. It flew great, but with the Magnum on it instead of the OS as I couldnt find a new motor mount that matched the old one, but the Magnum happened to be a perfect fit. It flies a little quicker with the OS, but the Magnum is still new, so give it some time.
Anyhow, after IΒ*was done with the Kadet, and very relieved it still flies well, and lands well, IΒ*restarted my 4* and took off, flying around, and had really relaxed with it and was finally comfortable with the plane where I can relax and enjoy it, and about 12 minutes into the flight, doing large loops, some rols, and few stall turns, hammer heads, etc, mostly at half throttle, and about a minute before I was planning to land, the right wing snapped off, IΒ*had just pulled up to start a loop when it went Craks, and I saw it flutter off, and the plane start its death spiral. It was done for I had no control over it, so I killed the ignition and spotted where it went into the corn field.Β* I packed everything up and went searching. I am definately getting lost plane alarms for my planes, what a PITA. IΒ*eventually found it right about where I thought it would be, but have not found the right wing, got dark so will go looking for it tomorrow, and hopefully get it before tehy harvest the corn and hope the servo is still good. The one in the left wing appears to have been stripped, so verdict still out on that, but the rest of the gear looks OK, the ignition module got lost somewhere on the walk back through the corn field.Β* The only part still in OK shape is the tail, but its pretty much a lost cause.
This will be my last ARF, after this I just dont trust something that IΒ*didn't build. My Kadet has been thrown around the sky much harder than I did the 4*, and has been smacked into things a few times, and not once did I ever have to worry if the wing would snap off. The construction on the ARF is not very good, the spar does not go all the way to the center, but ends at a plywood box that the aluminum joiner slides into. It looks like that is exactly where the wing snapped off. IΒ*wont know for sure until I find the wing.Β* Now heres the weird thing, the wing that had the most cracks in it and needed the most repairs was not the wing that snapped off.Β* The broken one just needed some reglueing at all the joints, and looked like it was fine.
IΒ*really liked flying the 4*, but after this I dont know if I will build another one, or something else, but it wont be an ARF, it will be one I build that I know wont break apart under mild aerobatics.Β* It had a couple minor dings hitting corn stalks, once on take off and once on landing, but at very slow speeds, the first one cracked the leading edge at the last rib, the second one knocked the tail wheel off, but the wing was fine. Neither of those should have caused any damage to the spars, at least they would not have done so on my Kadet, but in any case, I am not too thrilled with this.