I have been searching and reading all I can about how to choose motor size for a plane that has been specified for a certain size glow engine. Although the information I have been able to find is both consistent and informative, there is one thing that does not add up:
Let's look at a .40 size trainer as an example. It weighs around 5-6 pounds. From what I have read, a power loading of 75-100 W/pound is recommended for trainers. This means I would need 375-600 Watts of power for this plane.
It is standard practice to put a .46 on .40 size plane, even for a trainer. The OS .46 LA is rated at 1.18HP, or about 880 Watts. The OS .46 AX is rated at 1.63 HP, or over 1200 Watts.
Why does an electric only need half (or even a third) of the power you'd have used with a glow engine?