In the course of making repairs to my BC small pump (impeller fail), I found that one of the brushless motors I have on hand fits the pump!! You will need to fab up a brass impeller or back out the setscrew and ream the shaft hole bigger on your existing impeller (because the shaft is bigger), but that's not too bad The motor is at: http://www.hobbyking.com/hobbyking/...oduct=8474 and although it has a 3mm shaft, I will be wrapping a few layers of aluminum tape on the shaft (to get to 3.2mm) and then notching a spot for the setscrew in the metal of the shaft. Commentary from the aircraft guys is that this motor compares most favorably against Speed 400's. I will post a followup after I get the pump reassembled with the new impeller. I will be controlling this motor with a 30A aircraft ESC that is also from Hobbyking. Why aircraft? This is a pump motor, no need to be bidirectional. This makes it cheaper (~$8/each) . I am epoxy-potting it against a nice piece of aluminum to use as a heat sink, and the motor isn't rated for nearly 30A so I shouldn't be stressing the ESC out. ...and another view. The impeller visible in the pics is a 2-blade impeller, the precursor to the 4-blade impeller that will be in Scharnie in October. It has also occurred to me that if this motor will mate up with a pump made for 380/400-size DC motors, that it will also mate up with a BC 400-size gearbox which is also in Scharnie. If only I had a few 30A car ESCs coming in this week...
Did some testing over the weekend with various motors... I found that my medium-sized 400-size 1900kV motor will turn a full-size pump nicely, although it will trip the over-current trip on the ESC if run up to full power (can run indefinately at 90% of the trip-point). The small brushless pictured above will run all day long on a BC small pump with a 30A ESC. I have a bigger 2100kV 400-size motor (long casing, inrunner, with cooling fins) that I will be testing on my home-made pump for MN Jacques Cousteau (CPOE cruiser). Should throw a lot of water! Also, found 5mm collars that are usually used in RC helis; Brian K bought some large 550-size brushless motors (5mm shaft) that he plans to cast a pump impeller for, using the 5mm collars. I'll post updates as we get them.
