[samste]

I've just put a 3900kv ducted fan motor in there, 40amp ESC, standard prop...... ummm...... should I be scared....


What was that Kevin(?) You want to have a race....? :-D

If it doesn't blowup first, yeah I'll race :-)

I think a 3900kv motor is a bit to high kv for the stock 8x5 prop setup
(i'm guessing it would draw approx 80 amps)

I think if you were looking for more speed using stock setup prop you would be looking at upgrading the stock 1250 kv motor to 1450kv and it would be approx draw 40 amps
It only a small amount of kv increase but a huge difference you would see.
Alternately increase prop size to existing motor to 9x4 or 9x7 and this would be a major improvement.

just my 2 cents worth
Remember its only a kinetic not a speedster glider, its not design to cope with high speed
Steve