ETLB Squawk Forums — Archive

What are we all doing about the 6061 t6 spar carry through material? I can only find 6063 t52 from the aircraft suppliers. I am looking for the 6061 t6..... 1 inch U channel.

You can use 6063 T52.  My 1100R plans specify either alloy for all the channel.  It will be every bit as stiff as a carry through made from 6061 T6 because the shape is the same and Young's modulus is the same for both alloys.  The bearing strength is the problem.  The bearing strength of 6061T6 is 69000 psi.  The bearing strength of 6063T52 is about 35 kpsi.  Is that enough? For an 1100R Minimax the steel wing pin will put a stress of 2200 lbs /0.0625 in2 = 35 kpsi at  4.4 g's for a safety factor of 1.  At the normal category 3.8 g's the stress is 30 kpsi.  An easy way to decrease the bearing stress to an allowable level is to use a bushing.  A 3/8" o.d. steel bushing would decrease the stress to 23 kpsi and the safety factor is 1.5.  

For reference..  This carry through is supposed to be trimmed thinner in the middle part, right?  That's how mine is.

Thank you guys...........Your quick

I like the sound of that bushing. I might endeavor to add one anyway even though mine is.. whatever it is.