Champ Lift Rings

gusc · Post by **gusc** » Mon Nov 24, 2008 21:14

Dusty,

Is that an airplane or a snowmobile??

Obviously I was behind the curve on this one. My lifting straps are under the top cowling on the engine mounts and used to lift the nose for LG work.

Do your straps allow lifting the airplane level? I presume they are on the main spar carry through?

Is this safe for the airframe? I wouldn't think the fuselage is very strong at the top since it is designed to support most of the aircraft weight at the bottom.

Dusty · Post by **Dusty** » Mon Nov 24, 2008 21:21

Gus - it is a snowmobile with wings.

I can indeed pick all three wheels up with those straps. It is on the front spar attach bolt, which I presume also holds up the entire airframe every time she flies and is built to do just that. As far as I know they've been there for 10,000 hours without mucking anything up.

gusc · Post by **gusc** » Sat Nov 29, 2008 16:37

Dusty,

10,000 hrs is probably a pretty good test!! However, the lift straps were only used a tiny fraction of those hours. The rest of the time they are freeloading.

The main spar carry through only carries part of the air load. The lift struts through the lower fuselage attach points carry at least half and, I would guess, more than half the air load. Probably the reason they are called lift struts. Since I'm not an aeronautical engineer I don't know the exact proportions.

Also, the rear spar obviously carries part of the air load, but probably not a big proportion.

My guess is that only with a cantilever wing do the spars carry all the air load.