Colin, While thinking of your Lap Belt Support, I thought of another more likely scenario where you could end up in serious difficulty with the method that you chose to attach your belts. You appear to be a fairly significantly sized individual, you probably weigh a little over 200 lbs? Ask any of the flying KR pilots what its like to hit turbulence in one of these little birds. Everyone of them will tell you it's not fun, maybe even downright scarey. With a lap belt attached through the rear spar, (yes, you should put doublers made out of plywood and or aluminum angle) you would be assured that the lap belt attachment stays put, therefore keeping you restrained when you encounter turbulence. If memory serves, isn't the KR designed to carry -4 G's? That means that attachment must be designed to carry at a minimum 1200 lbs ((200 x 4)x 1.5)=1200 lbs. This is the load per side i.e. pilot only. Lets say you're carrying a 150 lb passenger. Add another 900 lbs limit load to the same crossmember, skin and lower longeron, and you're up to 2100 lbs. That's at only -4 G's If you look at the 7 G case, you're looking at 2100 lbs on your side alone, 3675 combined limit load. The main problem that I see with the crossmember approach that you have made is that you place the lap belt fasteners in tension, not shear. The whole installation is a tension load. Generally speaking, if you load identical fasteners, one in shear, one in tension, the tension loaded fastener will fail at around 75% of the shear loaded fastener. Some people will want to argue about it, but ask any engineer, they will tell you that it's a much more effective joint in shear than in tension, which is why we always try to design our joints for shear. The strength department typically knocks down our fastener allowables by as much as 50% when the fastener is tension loaded. OK, so how would that equate to your installation? Double the limit combined load, that is what you have to design that structure for or 7350 lbs. The lower longerons and skin were never designed to carry that kind of point load. --- Colin <[email protected]> wrote: > Yes it does Dana, and they are straight back from > individual belts to their own brackets on a angle > bracket attached to the longerons. > Colin & Bev Rainey KR2(td) > [email protected]
===== Scott Cable KR-2S # 735 Wright City, MO [email protected] __________________________________ Do you Yahoo!? Free Pop-Up Blocker - Get it now http://companion.yahoo.com/
