Motors acting up when I put a prop on. Why?

[quadplay]

First post here guys, so hello!! :tennis:

I am using 2 4000mAh 3S in parallel, with a TOW of around 5 lbs, a bit on the heavier side. 30 A OPTO esc, Naza M-v2 mc.

Previously, I used the base Turnigy 2830 motor, and it flew pretty decent but the battery drained fast. So looked into eCalc, and came up with a better motor/prop combo that would utilize the twin 3S batteries better.

The motor I chose was the NTM Prop Drive 28-36 750Kv . All the specs checked out, so I bolted them on. Tested without props on, the motors were spinning up to max speed on command, and varying the speed with throttle and other inputs just as they should.

But when I added the props - I got 13x40 carbon fiber, balanced - the motors would start up run on idle, but will not accept any more inputs. In fact, I put in any prop, the smallest I have, with still the same result. I tested it with one motor with the prop on, and that motor will show this idle behavior, and the others will spin faster and on command.

I am sort of at a loss to explain this behavior, and any solution is appreciated.

 

[Benjamin Kenobi]

This is normal below 50% throttle. Did you try going above 50%?

 

[quadplay]

Yes, tried full throttle. No response other than idle at wot. So if I do that test with one prop off, then that motor would run full speed, and the three others idle.

 

[kloner]

does it make a noise, flip back and forth? if so we call it commutation problems and the esc are incompatible with the motors.

 

[quadplay]

No, no back and forth. It just spins smooth at idle speed. The esc compatibility is a possibility, but why would the motors work just great without the props on? I even tried to induce some resistance on the noprop ones by holding my finger against the rotor, but it still spins according to demand. The moment I put a prop on it, that goes to idle.

I know, hard to comprehend/believe. I can make a video of it on case anyone is interested.

 

[quadplay]

No, no back and forth. It just spins smooth at idle speed. The esc compatibility is a possibility, but why would the motors work just great without the props on? I even tried to induce some resistance on the noprop ones by holding my finger against the rotor, but it still spins according to demand. The moment I put a prop on it, that goes to idle.

I know, hard to comprehend/believe. I can make a video of it on case anyone is interested.

I replicated the behavior just now - what I did different this time, was to add the resistance (with my finger) before I applied the throttle, and bingo, the motor was practically powerless. It was trying to rotate out, but from the slow idle, I could stop the rotation by just holding it a bit firmer. The other motors (all prop-less) of course went full speed. So I tried letting the one I am holding go, and it soon (within a second or so) picked up speed and went full out, proportional to the throttle. And once on that speed, it cannot be stopped.

So - the prop, even the lightest ones I have is adding some resistance, and that is making the motor go into a limp mode. Not good - and I can't think why.

 

[cootertwo]

Just guessing, but maybe something to do with the "start" setting on the ESC's. Some have "soft", "normal", and "hard" start. It still amazes me how some of these components work well together, while other combinations can be a real PITA. I've got one bothering me now, with too high of a "arm" speed, but can't figure out how to get into the programing mode of this particular ESC. Some are different than others. Just another speed bump on the road of Multirotors! Ha!

 

[kloner]

that would be a good easy start, what esc are they? got a programming card?

When you get it spinning, what happens when you rapidly change speeds like in my video? 1/4 to full throttle work? half to full throttle nice and smooth?

 

[quadplay]

that would be a good easy start, what esc are they? got a programming card?

When you get it spinning, what happens when you rapidly change speeds like in my video? 1/4 to full throttle work? half to full throttle nice and smooth?

So guys, it is the ESC compatibility. My DJI OPTOs are not playing well with these NTM motors. Last night, after I exhausted all options, I thought of switching the Opto with a Turnigy ESC i had around. And just like that, it was like blowing new life into the motors. So I put the OPTOs away to be used for another build.

So thankfully, I think I am back to flight readiness.

Thanks again!