It's not about the horsepower though. The OS spins a MUCH smaller prop than the AXI, and the AXI isn't even a good motor these days. I'd like to see you even try to hover with a 7-8 in prop that the OS would turn, compared to a 11 incher the AXI would. The thrust on the OS would be much less too. Granted, the OS would fly the plane much faster, but speed on aerobatic 3D planes is not what we're after. Plus, 1 horsepower is something like 725 watts. You could easilly prop a similar motor, weighing the same (2.5-3 oz), (the AXI isn't quite up to par) for 350 watts, which is the same as the .5 HP the OS puts out.