Design Allowables for Composite

[flyingriki]

I did some reading on this subject while searching for the mechanical properties of composite materials. It turns out the allowable stress/strain you can use in your airplane is FAR LESS than either the strength of fibre or the laminates. Thus the approach of "make your laminate, load it with sandbags, and see when it breaks" is incorrect and dangerous in airplane design.

Tell that to the guy that pioneered many of the designs and then built an operational spaceship......
Actually he designed first and later found it took a hell of a lot of sandbags and yet the aircraft was still light and a delight to fly.
My goodness - can that be true?