Originally Posted by orenda635
As for engine, I would just convert motor watts to horse power and go from there.
They don't go hand in hand... If yo do so, you will end up underpowered. I'd guess it has something to do with prop efficiency or so. Any way, I don't know why it is so but it just is... I've been flying a .40-sized pattern plane with 450W of power from an electric motor. Not quite eguivalent to a .40 2-stroke, right? (OS .40 LA - 1hp = 746W)