What a tough day. On my seventh flight of my Sig Cap I experienced a wing failure. The plane was powered with an OS 1.60. I pulled a loop at half throttle, at the downside of the loop I reduced to idle...no problem. On the exit side of the loop with the wings level the wing failed.

At the trailing edge it failed near the end of sheeting, beginning of the aileron. At the leading edge it departed just beyond the wing joiner. The shear webs in this area don't always touch the spar. Also it appears there wasn't much glue in these areas. The forward plate that the wing dowels drill through pulled away clean where the wing released.

Obviously it is a total loss. It was a beautiful plane and a great flyer but it appears the wing assembly could have been better.

Has anyone else experienced this. I have had good luck with Sig,but now I'm leary. I know they have had wing failure in the Sukhoi S31.
Rockfish

Sorry to hear about your loss. I had the Sig cap and the extra and sold them both before I ever flew them. After hearing all the stories about the problem you had I didn't want to chance it. The guy I sold the cap to had bad flutter on the aielron and it went in. Sig has a serious problem with their 1/4 scale planes, not sure if it's quality control or what. I know alot of people havn't had any trouble with their wings but I'm going to stay away from them myself.

I would box that baby up and send it back to sig and see what they say, maybe they will at least send you a new kit.

Hey Cap,
Thanks for the comments. What you suggest is exactly what I'm going to do.
Thanks
Rockfish

MY SU31 wing failed at the same point as yours on the trailing edge. Fortunately it did not fail completely. I suspect the wing design is the same. After removing the covering I discovered what I consider a bad design in this area. I made some changes and added carbon fiber reinforcing in the corner of the aileron in the wing. I also added carbon fiber tape to the upper and lower spar about half way out on each wing half. In addition, I glassed the center section with 8oz cloth..

IMO in an attempt to make these planes light, they have sacrificed competent design.

Just my 2
Vince

Rkfish did you glass the center section when assemblying the wing?

hate to hear about your loss, you may have just gotton one of the Monday or Friday made kits. I had 2 of them and that is one smooth machine. What size prop, and make of prop were you running? it sounds like glassing the wing would have not have made a difference on that break. The sig wing on the cap is def. built light the spars don't run all the wing to the end of the tips. Are you going to get in touch with Sig?

RickM,
I did not glass the center section of the wing. It failed outboard of the fuse, approximately 8" from centerline of the wing.

Rockfish

Krayzc,
I was running a 17/10 APC. To answer your other question, I do believe I will contact Sig. Normally I would pass it off but the I can see glue joints that pulled away clean, web shears not touching the spar, etc.

Looks funny to me.
Rockfish

Vince,
I am with you, I believe good design has been sacraficed in this case for sure. It sure was surreal to watch the wing separate in flight, the fuse and port wing go one way and a little more than a third float the other way.

Also, this is interesting, other than the failed section on the wing where it parted, there is no wing damage. The section that went down with the fuse doesn't even have a dent on the wing tip and the wing bolts sheared as advertised. That is amazing in light of the fact the fuse is totaled from the rear of the wing seat forward.
Rockfish

Here is the rest of the story. I sent the wing to Sig. Their customer service people were very helpful. They received the wing on Monday 8/12.

Today, Thursday the 15th, I received a brand new airplane.
Sig stands behind their products......
Rockfish

glad to hear you will be back in the air! i sure did enjoy mine back in the day. She one sweet machine.....