ShyTorque,
One must wonder why you started taking off in front of a glider which had no means of going around!
Well, we simply never saw him, that's why! I was flying at a controlled military airfield (with an ATZ of course). There were five powered aircraft in the circuit. One of them was in the process of landing and after waiting for a while at the holding point (during which time we had been looking out for other aircraft - it was a full pattern) we were cleared to line up immediate behind the next landing traffic and wait, which we did. We were cleared to takeoff from that position after waiting for the preceding aircraft to clear the runway. The white glider apparently came out the west, out of a very low sun, in very hazy conditions and cut across the live circuit. He had a radio but had not bothered to call ATC. No-one else, including ATC saw the glider until it landed (we saw it just before it landed, as I said it landed over us from behind).
The airfield was all short grass, It was at least 3,000 feet wide and only slightly less in length, bearing in mind the runway in use was 31. The glider could easily have landed on any of the airfield, there were three runways in all but all of the field was suitable for landing out. We were already lined up on the runway when he made his final approach, so he was behind us as we were held on the ground. He chose to land on the active runway, even though he could easily have "side-stepped" at any time and landed alongside the active runway.
If he had made a simple radio call things could have been very different. He just didn't bother. As it was, he was lucky our prop didn't split his skull from behind. A solo student probably wouldn't have been able to fly the aircraft partly off the ground and turn left away from the glider as I (only just) managed to do and certainly would not have been able to stop the aircraft.