I thought Turnigy made a 44mm. I thought I used them on my Twister. All I could find now was a 51mm. As a side note, they did not do much for cooling.
Ken
I don't fly electric, but try to read as much as possible about their operation. I often wondered about the effectiveness of slotted spinners for cooling. Some models have other slots and scoops for cooling air. I wonder if you were to take some smoke, and at any RPM, introduce smoke the the air flow near the point of the slotted spinner. The watch the area of the exhaust slots where the cooling air is intended to exit and see if there is any smoke coming out there. If air is getting through the slots, and you don't have any place for the air pressure to exit, it won't cool anything. I would tend to think that a slotted spinner that is turning at operating RPM, would just tend to make a bubble with no flow.
This brings up another question about cooling. Do any of you guys have a filter on the cooling air inlets? This became a question when a local flying buddy had his motor seize on him in flight one day early this summer. The immediate thought was a bearing took a dump, as he had been flying this model for quite a while with no motor issues. Then when we examined it, it looked like some of the wires on the armature were burned. He changed out the motor, and I asked him for the old one to do a post mortem exam on it. Got the motor apart, and found that two magnets had come loose (they are just glued in place) and jammed the armature. What knocked the magnets loose was all the junk, grit and gravel I found in the motor in between the other magnets! What we thought was burned wire on the armature was some kind of large debris which I'm not sure what it was. May have been the remains of a bug! The bearings seemed fine and I was tempted to just glue the magnets back in place and give him the motor back to test run, but thought better of it, after thinking that I didn't know if any of the other magnets were near separating from the case, as the motor was pretty old ( it was an airplane from Walt Brownell's collection and built quite a while ago. He flew the model quite a bit.)
So, it made me wonder if any of you guys thought about the junk and debris that can get inside a motor and stay there! I should have done the exam on a piece of white paper and photographed the junk that came out but didn't think of it at the time, not expecting to find what I found.
Type at you later,
Dan McEntee