Jim & Netters: The discussion awhile back about belt attachments was between myself and Colin Rainey.... If I recall the bottom line of that discussion was 1/4" minimum diameter bolts through .16 thick aluminum. 3/16ths fasteners just weren't strong enough to carry the weight of an average sized pilot to the G loading a KR is capable of generating. A 1/4 inch diameter bolt (aircraft grade) develops it's full shear capability at .160 thick 2024-T851 according to the Mil-HDBK-5H on material allowables. 2024-T851 is a stronger material than 6061-T6, you could use either, 2024-T851 would allow about 4660 lbs of shear per attachment. 6061-T6 is only good for about 3961 lbs (about 15% less). This is of course assuming that you keep at least 2D + .03 edge distance or greater. Please remember these allowables are for an aluminum joint, and in regards to the KR seat belt attachment, you'll have to factor in the fact that the joint is aluminum to spuce, which is obviously much weaker.
As far as belt attachment location, find the "H"-Point of the occupant (center of the hip socket) and draw a line horizontal from there. draw another line 45 degrees below the first line again starting from the H-Point. This is your lap-belt attachment zone. Because we sit typically in front of the rear spar, you could unintentionally locate the lap belt attachment higher than your H-point, which would do little for vertical restraint, and be very uncomfortable during flight. As always, your results may vary, please don't take my word alone, test, research and do the math for yourself..... Jim Morehead wrote: >what thickness angle alum. would be best. >Jim Morehead >++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ You may be thinking of the following: http://home.hiwaay.net/~langford/flesner/fittings.jpg ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ Scott Cable KR-2S # 735 Wright City, MO [email protected] --------------------------------- Do you Yahoo!? New and Improved Yahoo! Mail - 100MB free storage!
