fly_boy99's blog archive for February, 2007 - RC Groups
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Archive for February, 2007

c/f Motor

Posted by fly_boy99 | Feb 27, 2007 @ 05:14 PM | 4,399 Views
Well c/f contacted me awhile ago and I told him that at some point I'd build him a motor. The 100mph thread prompted me to play with this one.

I can say that with the 4.1x4.1 prop and 114mph pitch speed for 25A draw is pretty darn good. I did try with the 4.75x4.75 and it was clipping on the high end so this one will need field testing next to see what she does in the air unloaded. It pulled 36A on the 4.75x4.75 and it was right on its constant rating.

I have posted all three graphs:

Kv Graph
4.1x4.1 Graph
4.75x4.75 Graph
4.1x4.1 4S Graph

One other item of interest is to run this on 4S with the 4.1x4.1 and see what she can do. *edit* Added graph... 124mph pitch speed on 4S doing 32A without going WOT. This one was a little below 3/4 throttle and was putting out 500W, she must be dumping heat like no tomorrow!!! That's about 65% efficiency and getting worse as you push it.

Posted by fly_boy99 | Feb 22, 2007 @ 08:35 PM | 4,188 Views
Paul asked me to build him a motor that would stay below 40A and get some good speed but have enough thrust to back up the might 36" Demon.

I'm happy to say I've met the task and hopefully we will have a powerplant that will drive the Demon to over 120mph while carrying verticle lines very nice.

The motor comes in at 3000Kv on a K283 Double stator setup with 9T of 22g and teminated Delta. The motor also runs with 6 magnet poles.

I made three runs with good speed props. Namely the:

Astonishingly the motor with the bench testing on Kv determination and the following prop tests net the motor temp no more than 85 degree F. I was quite surprised at this and I am very happy with the results. Looks like one can go hotter and squeeze out a bit more performance.

EDIT: This motor actually didn't work out for a couple of reasons but the main one is that the motor did not provide enough thrust to give the performance you need out of this wing. This motor could work for very sleek airframes and be below 20oz AUW. I am pursuing the 3014 motor from Scorpion to provide the grunt we need.


p.s. All tests were done on a 3S pack. If we went to a 4S pack we would get even better power/performance!!!