There's so little air up there that the gliders would go supersonic rather quickly until they got into denser air. This would mean you'd need low aspect dart like wings so they don't get ripped off but that means the landing performance would be abysmal. You'd have landing speeds nearing 200kts (as opposed to ~50kts for a normal glider). Since kinetic energy is the square of speed, any fuck up would be very fatal at those speeds.
The U2 was famous for this issue, the pilots were flying on a knife edge because a stall (a less aggressive situation that deploying from a static balloon) would mean the plane starts accelerating well beyond it's structural limit before you can do anything about it.
Yeah, I was thinking about that...you'd likely need wings that could be pulled in close at higher speeds/altitudes or to not go quite as high. I would be happy for the later...just get rid energy needs of gaining altitude in a glider.
Funny enough, this was a thing in Pandora's Star. There's a weird chapter where the author gets bored and describes this exotic glider extreme sport where people ride variable geometry winged gliders through mega storms on another planet.
The U2 was famous for this issue, the pilots were flying on a knife edge because a stall (a less aggressive situation that deploying from a static balloon) would mean the plane starts accelerating well beyond it's structural limit before you can do anything about it.