Agreed. It is probably too generous to assume the ideal glide ratio and simultaneously assume generation via the prop. Depends on a lot of stuff though. It's n

Agreed. It is probably too generous to assume the ideal glide ratio and simultaneously assume generation via the prop. Depends on a lot of stuff though. It's not a question of energy creation -- the energy of the system includes energy in the air. Generally freewheeling generates more drag than a stationary propeller (google "ESC brake vs freewheel" to see what R/C hobbyists have to say about this). However, you may have an unusual situation where maintaining the ideal glide velocity requires braking, and in such a case it is presumably more efficient to brake via the propeller. Suffice it to say that even in the ideal case, this particular aircraft would have trouble maintaining flight via solar power, but other aircraft are proving that this is a viable possibility.