its been a long time since Ive done an update, i haven't really had a lot to say because the progress has been backwards and forwards. 3 motors and 2 esc's later Ive seem to have got some kind of success that doesn't result in smoke
. Ive now got running a 1900kv 2830 outrunner on 3s spinning a reduced diameter 26mm impeller with lower profile blades. Anyway enough waffling:
http://www.youtube.com/watch?v=o3ULmAkzpgwI must apologise for the quality of the video, i was on my own and had to put the camera down and sail the boat in shot. There are some leaks between the motor and the pump casing which ill address later once I'm happy with the motor.
Its actually surprised me how much power is required to run a centrifugal pump as a method of thrust. I was hoping that the rule of thumb for matching props to motors would be transferable to pump impellers but it seems not, the diameter of the outrunner needs to be larger than the impeller. The boat was initially pulling 25 to 30 amps on 3s with the old impeller and requiring nearly 340 watts of power. Its a little less now but still around the 300w range, its nowhere near as efficient as a propeller. I hope that the extra torque of a 3530 1700kv Ive got coming will overcome this and hopefully I'll be able to up the impeller diameter again.