The G-109B is a powered glider used in a training role by many gliding clubs and the Royal Air Force's Volunteer Gliding Squadrons. It's RAF designation is the Vigilant. It is powered by a four cylinder engine that runs on standard Octane-100 Avgas.
Due to it's enormous wingspan for gliding, it has a very low stall speed (and a correspondingly low unstick speed) of 45 kts. The advised approach speed to avoid ballooning horrifically (I should know, I have done it a few times myself) is 65 kts. Stray slightly above but never below on your finals.
A negative consequence of the large wingspan is a marked tendency to adverse yaw, requiring liberal use of co-ordinated control. Don't skimp on the rudder! Also, it is light, and drifts a lot in crosswind; it rolls when only one pilot is present, and it buffets in thermals. Thus you will find yourself being heavy-handed, but the only way to get any control is to be a bit forceful.