Stuttering Propellers

[Newtman]

I flew on 8/12 and the Phantom worked perfectly, just like it has every single time since I received it about the end of March. It has endured tree landings, bush landings, etc (early on), it has never missed a lick.
However, today, I went to fly and I went through the regular preflight steps and when I brought the sticks back and to the inside to start the props, the "stuttered". They moved in a very jerky motion looking like they would jerk backward a little bit even. I was flabbergasted!
Now, I had ordered and installed an ImmersionRC 600mw VTx by just plugging the same connections that I used for the 250mw that came with the Fat Shark equipment. I had hooked it up and made sure it displayed on the Black Pearl, and it did - perfectly.
However, I had not tried starting it. One other thing. I thought my batteries in the Tx may be weak, so I removed the battery cover and was amazed to find that rechargeable batteries were in there. Well, I removed them immediately. I put regular AA batteries in the Tx. Still the same problem. I tried disconnecting the VTx. No help.
I am really stumped. I'm so use to the thing performing flawlessly, I was just dumbfounded. I will try to upload a video of it tomorrow.
Could someone please help?

 

[noiseboy72]

Check the battery was fully inserted and correctly charged. It is possible to get a poor connection, causing insufficient current from the battery.

Don't think this is anything to do with the tx or Vtx, but could be an issue with the NAZA, if it affects all 4 motors. What was the light sequence on the 'bird?

Is your flight battery OK? If you have had a few crashes and plenty of flying, it might be getting to the end of its life, so this could also be a factor.

 

[Newtman]

I think I may have figured this out. When I removed the motor screws to re-install the prop guards, I put the screws in a nifty metal plate that I got with a dremel type tool. The plate was magnetized. At the time, I thought this was great because I didn't have to worry about the screws rolling around and maybe loosing one.
After further consideration, and thinking about my stuttering propellers, I think that the now "magnetized" screws intifered with the motors.
Does this make sense?
I'm going to make me a demagnetizer today or tomorrow and demagnetize the screws and try it again. I hope I haven't "screwed up" (no pun intended) my motors or something worse.
I'll post my results of the demagnetized screws.

 

[Fyod]

Yea that does make sense. Try taking two of the screws alone and see if they magnetically react.
Also, are you installing the correct length screws? The prop guard ones are longer and should not be fitted without the prop guards.

 

[Newtman]

Thanks for the input. I did not switch out the screws when I had the prop guards off. I did check the magnetization on the screws and sure enough, they were magnetized. I am going out of town on Tues. I will wait to see if the magnetization is gone when I get back on Saturday.
I will check my screw lengths too.

Thanks again,

 

[N017RW]

The long(er) screws + no prop guards = damaged motors.

There's no way the screws are magnetized enough to upset the motor operation.

However the longer screws intended to be used with the prop guards [only] are too long to be used without them.

Good chance you ruined the motors with the longer screws if that is in fact what you did.

 

[tferrari]

I flew on 8/12 and the Phantom worked perfectly, just like it has every single time since I received it about the end of March. It has endured tree landings, bush landings, etc (early on), it has never missed a lick.
However, today, I went to fly and I went through the regular preflight steps and when I brought the sticks back and to the inside to start the props, the "stuttered". They moved in a very jerky motion looking like they would jerk backward a little bit even. I was flabbergasted!
Now, I had ordered and installed an ImmersionRC 600mw VTx by just plugging the same connections that I used for the 250mw that came with the Fat Shark equipment. I had hooked it up and made sure it displayed on the Black Pearl, and it did - perfectly.
However, I had not tried starting it. One other thing. I thought my batteries in the Tx may be weak, so I removed the battery cover and was amazed to find that rechargeable batteries were in there. Well, I removed them immediately. I put regular AA batteries in the Tx. Still the same problem. I tried disconnecting the VTx. No help.
I am really stumped. I'm so use to the thing performing flawlessly, I was just dumbfounded. I will try to upload a video of it tomorrow.
Could someone please help?

Sounds like an issue with a motor speed controller, not the motor itself. I've seen this same issue with my unit. Currently one of the motors rotates slower at idle and pulses once in a while but is the same speed as the others when throttle is increased (I have measured it with a timing light). There are no flight symptoms after over a dozen flights.

Can you post a video that shows the symptoms you are referring to?

 

[HarryT]

The long(er) screws + no prop guards = damaged motors.

There's no way the screws are magnetized enough to upset the motor operation.

However the longer screws intended to be used with the prop guards [only] are too long to be used without them.

Good chance you ruined the motors with the longer screws if that is in fact what you did.

Yes, this is something my dealer specifically warned me about when I bought my prop guards - that when I took them off again I must use the original, shorter screws. The longer screws will go up into the motor and damage it.