I have an ESC / motor question if anybody could help.

I was previously sold an Xtra 21 ESC to use in a Simprop Cap231 foamie which was running the stock Acro 280 geared motor. The plane always seemed to struggle to perform and only just barely flew. The battery pack was the stock recommended one - 8 2/3 AA cell 400mah I believe. Could the ESC therefore be to blame ?

I now have a GWS mustang foamie with the kit supplied 300 geared motor and was hoping to use the same (Xtra 21 ESC) if it's suitable.

Basically how do I calculate the amps drawn from the motor to determin which ESC I need ? and, does it matter if the ESC is over rated for the motor or does this make it inefficient ?

The Xtra 21 is (as indicated by the name) rated at 21amps.

Thanks for any help.
Pete

Is that the RipMax Xtra range? Mine is marked 22

The only penalty for using a bigger ESC than necessary is WEIGHT.

And the Xtra 22 has a switch, which is nice.

I have no problems with speed 400 models on the 12A and 480 models on the 22A.

I suspect that your woes are more to do with poor motor/pack/prop/box matching than the ESC.

That ESC ought to be fine for a 300 setup.

Roughly speaking, all other things being equal, a 300 draws about 6-10A, a 400 about 7-11A and a 480 10-12A, when running in a good setup.

Thanks Vintage1,

You are right, it is the ripmax xtra 22. I will try this and see how the maiden flight goes.

Cheers