wrote:
Robert Loer wrote:
Plans call for wing spar to fuselage carry through attach fiitings to be
7/8x1/8 4130 steel. Advisability of using 9/16x 3/16 6061-T6 aluminum as I
have it on hand.

Your thoughts please. I have plans for another ship which uses the 6061-T6.


At the maximum design load, how much deflection do you have with each?

What is your factor of safety with each?

If you don't know, don't substitute.


Just for fun, lets work it out.

The 4130 fitting will have a yield strength of around 7600 lbs @70 ksi
yield. The aluminum piece will have about a yield of a little over
4000lbs at 40 ksi yield.

You would have to stack two of of the alum pieces together to get the
same tensile strength. Which would probably open up a whole new can of
worms so it's better just to go with the steel.

John