earthsciteach, I like your idea of using the sabot as padding to help soften the force exerted onto the glider. But I wonder if you need a full sabot. You really only need a plug behind the glider to make the cannon airtight. Maybe make some sort of dolly that holds the glider firmly to a plug. Maybe just have two sticks/shafts coming out of a plug to hold the glider to it. And then make the plug out of a soft foam, something compressible. The soft foam will compress to absorb some of the impact of the air/explosion but still push the glider out with full? force. Once the glider and dolly/plug come out of the tube, then the two sticks can either fold back away from the glider, or just let the glider slide out. I'm thinking one stick on each side of the fuselage of your glider to hold it firmly in place. But you'll probably need the sticks bolted down tight to the fuselage in some way so the force is spread through out the fuselage and so the force isn't all exerted onto the tail. With a sabot, the force will probably still be all on the tail of your glider, depending on how strong the sabot is. A hard sabot with a soft back will work great, it just seems like a lot of work. A soft plug with a hard point to mount two arrow shafts on just seems a lot easier.
