Motor static testing - RC Groups
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This thread is privately moderated by RicksterRC, who may elect to delete unwanted replies.
Oct 03, 2012, 02:28 PM
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Motor static testing

I did some motor testing.
I did static testing. I weighed the helie's All Up Weight.
I then held them down to the scale with a wrench jammed through the skids and zeroed (tare-d) the scale.
I then recorded the "negative weight" at various times. Initial, 1,2,3 and 4 minutes and the time when the motor was no longer generating enough lift that it would be able to carry the heli. I compared stock V911 motor, stock Y911 (yellow) and V911 with SP720 replacement.
Unfortunately, I don't currently have any working Bravo SX motors to test.

I used a 130mAH fully charged battery for all the tests.
I ran full throttle the entire test.
(would be interesting to do a test where the throttle was set to the weight of the heli and time it - but that would require a lot of effort).
All three helis have Extreme Delrin main gears. The SP70 is by far the quietest.
It spins by hand silently and many more turns than either of the others.
Note these tests were performed on a kitchen counter, so the heicopters were in ground effect.

I did try to record the Blue/White with SP270 motor's lift out of ground effect by tying a 3 foot string between the wrench and the heli. This proved extremely difficult as the string's pull made the heli terribly negatively stable. I had to hold the heli gently above the scale.
For the record, it created about 5g of lift or about 20% of the helis mass. Shows why a gram gained or lost makes a big difference in real life performance!

I have read in various places that adding external high powered magnets to the shell of a motor will dramatically increase it's power. I have some amazingly powerful magnets and just for fun I tested using them - one on each side of the motor can. As you can see, they added 1.9g to the heli's weight, and decreased the motor's thrust significantly. I think this should put this myth to bed.

It is interesting that while the SP270 objectively looks the best, subjectively (while flying), it seemed to lack the oomf of the other motors. I had added a drop of oil to the bearing before the test and that seemed to help in both the test and subsequent flight experiences.
Maybe it's the extra gram and a half of LEDs that ruins it's feel.
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Mar 13, 2013, 10:47 AM
Flying high!
Nice test I would have loved to see the Helios 100 motor in there too. I've seen some good reports of that one. It has a very attractive price atleast.

There is a huge difference in how and where you place the magnets on the motor. Did you just throw them in or did you find a "perfect" place for them? And if you did, how?

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