ORIGINAL: Arad
Thank you for your reply.
My English is not very good and I understood a part of your post but I think I did not understand other part very well.
Ok, let's check again.
From your post ... one of the important components for choosing electric engine is ''Watts per pound''.
So ... from your post ... for my r/c plane which its weight is 7.5 pound, I should choose an engine with 1125 kv ... ?!?!?!?!?!?!!!!!! correct?
next question ...
What do you suggest for my r/c? or ... Whitch one is sufficient:
1. 2215-22 TURN, 914KV,56G BRUSHLESS MOTOR
2. 3014-20 TURN, 1120 KV, 120G BRUSHLESS MOTOR
3. 3020-12 TURN, 972 KV, 155G BRUSHLESS MOTOR
No those are far too small and too high of a KV rating for your plane.
What KIND of plane is it?
Trainer, Aerobatic, 3D, etc. ?
Assuming a target of 140w per pound you'll need at least a 1100 watt motor.
That puts you down into the 500-600KV range using 5s or 6s LiPo's... but more information is needed.