On Thursday, December 1, 2016 at 4:03:22 PM UTC-5, Jonathan St. Cloud wrote:
Just wondering why glider are not made with pre-preg. Seems like it would save weight.

Some factors:
1 Molds have to be able to stay stable at curing temperatures and maintain their dimensions over a life of many cycles.
2 In the life of the glider, it will get broken. If the structure can't be repaired in a shop that does not have an autoclave(all the shops that I know of), it likely has to go to the factory for repair.
3 Most of the external structures in our gliders are over built to some degree in order to make them durable enough to live in the real world.
4 Pretty much nobody cares much about weight, except the little gliders. For all the rest we just want to know how much water can we get in it.
5 Prepreg materials obviously have storage requirements that add cost
6 They are generally more expensive and limited in choice of material properties.
7 Hybrid structures commonly used in modern gliders may well be limited by the availability of suitable materials. If you want your tail to stay on in a midair, you'd like to have some Kevlar in your tail boom. Or maybe you'd like some aramid in your cockpit to control where the catastrophically failing carbon goes. Tailoring the progressive failure of a nose is most commonly done with a mix of materials as well as laminating schemes.

FWIW