Can single engine planes glide from a falling position?
It's remotely possible, assuming you can find a suitable UFO :-) If you drop an object from an aircraft it starts falling with the same airspeed that the aircraft has, until drag or other factors slow it down. If you've ever seen a flour bombing competition (or just watched some WW2 movies or documentaries) you may have noticed that you drop bombs before you reach the target, not when you arrive directly over it.

So if the UFO is moving forward at an airspeed greater than the Stinson's stalling airspeed (65mph) - let's say 80mph - then the Stinson will fall into the air at an airspeed high enough to generate lift immediately and it will fly. If you already have the engine running and throttle up as soon as you fall out of the UFO, you will generate thrust and maintain the flight.

In reality - if there is such a thing when a UFO is involved - the Stinson is almost certain to lose some altitude and the wake turbulence from the much larger UFO will have a significant (and potentially very dangerous) effect if the Stinson can't stay ahead of it.