HI,
I have used the Emax BL4030 motors on a couple of planes. Not my favourite motors as they have a tendancy to flal apart. The published spec sheet is....
- BL4030 385KV.jpg (22.16 KiB) Viewed 3697 times
I have run these on 6 cell as all my batteries are 3 cell, so I always use multiples of three. From my files I recorded these as pulling about 43amps on 22.2volts so power was 955 watts. Prop speed was 385 x 22.2 = 8500rpm.
So if you are using 4 of these you have about 4kw. Trainer style flying requires 220watts/kg, sport flying 350 to 450 and 3D up to 800. So if we say 300w/kg for your plane to give reasonable umph but not crazy, then with 4000watts it could weigh 13.3kg.
You could get away with lower power/weight but it is not advisable as if you get into an awkward situation you have nothing left in reserve.
Battery size can be approximated by assuming a 10 minute flight on half of full amps. So in this case each motor takes 22amps for 10 mins, which is 3666mah. I usually find that without doing any 'crazy' full throttle flying this will give a 10 min flight and use approx 2/3 of the pack capacity.
