GregG7

I have completed construction of a 1/3 scale Balsa USA cub. The method of wing mounting depends on the wing struts for support. If the wing struts, or mounting points were to fail, the wing would most certainly fold up in flight. It seems that the point where the struts attach to the landing gear strap is not very beefy. I am concerned about a failure of the landing gear strap where the two holes are drilled. (See picture to get an idea of the area I am talking about)

I already had a failure of a metal bracket holding the tail struts. This bracket failed by just running the engine on the ground. Apparently, vibrations from the G-62 engine caused the metal to fatigue. (I have also attached a picture of this)

If anyone has experience with this particular plane, I would be interested in any deviations they have made from plans to beef up these areas.

Thanks
Greg

frequent flyer

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I'm scratch building one and thought the same thing. What did you do?

mogman

Hi Greg.
I built a 1/3 BUSA cub back in 1992 and it is still going strong. It is built the way the instructions said. The only thing I would change is where you have the hairpin clip fastening the wing struts to the fuse. Vibration will cause the holes to enlarge, leading to a sloppy fit. I use the same Du-Bro fittings but use a 4/40 bolt to really snug up the fitting. After all these years the holes in the strut fittings have not worn at all.
On the tail fittings, don't use the full length of the strap. I use the "shorter" of the two ends and bend where there is no hole. Again these have lasted all these years with no breakage.
If you are experiencing a lot of vibrations, check your prop balance and keep all your strut fittings etc. tight.

Cheers, Dave.