Phil,

I've been thinking about your testing just a bit and I have a couple of questions


1) did you put the total air load at that station as the load?

2) Why did you put the load only on the back half of the rib? (equivalent moment, or just being conservative?).




Depending on how you answer those questions your test may be pretty conservative -- especially it look like it failed at the upper center joint which would have been experiencing more moment than expected (if the load was uniform across the rib. Also, if you applied the total load only to the back half, the moment would have been MUCH higher than it would be installed on the aircraft.




Just thinking... I think those conservatisms may mean a fair amount of weight in the end And I'm guessing the wood ribs probably wouldn't carry half that load! It would be interesting to compare an original loaded in the same way. I do recommend applying the load more uniformly over the rib though -- it would b a much better indication fo failure.