@-alan- It's flown - manually! - in an inclined loop in the lee of the mountaintop, picking up a little speed everytime it flies
across the wind lofting up over the top of the mountain by aerodynamic lift forces - think of how say the blades of a wind turbine work - very high tip speed to prevailing windspeed ratio: hence need for very constant, high wind speed on the right-shape hilltop to get close
It's this guy, and he's done vids on youtube about it - very clever stuff:
http://www.dskinetic.com/transonicdp.aspx
Back of envelope stuff - from the site above, seems the gliders are about 12lbs in weight: I'll round that to 6kg for this new larger one; 548mph = 244m/s velocity - erm that's
357kJ peak KE - a massive amount of kinetic energy - the same as <twiddles/> a one tonne car at 42mph. Think about that.
Oh, and at the top of the loop, it is pulling nearly 100g lateral acceleration!