“That’s a glider”
The word you want is sailplane. Gliders show up in WWII pictures and probably had an l/d of about 8. The one in the picture is likely 40+.
It’s a generic name for a non powered aircraft as was assumed to be the aircraft he was flying when the crash occurred in a previous post. I have piloted these and when you can’t find an updraft, it is a very short flight.