I built an electric spad using a motor from www.hobby-lobby.com Go to the site and type taxi in the search and then scroll down and look at the motor. Its slightly under powered for a spad 40 size so I would bump up to a little more powerful motor.

This particular plane is a down scaled debonaire (SPAD) www.spadtothebone.com with a 48" wingspan. I scaled it down because of the underpowered motor hoping that it will zip along really well. I have yet to try it because its so windy today.