Motor test results after tipover. Are these figures normal?

damirkotoric · Apr 2, 2016

A sudden gust of wind tipped over my Phantom 3 Professional while it was stationery on the ground. It carried the Phantom a couple of metres before it came to a stop. The propellers were in bad shape and afterward I hear a clicking / hissing sound from the motors during startup and shutdown. I decided to test the speed of the motors and here are the numbers:

I also checked the heat of the motors after a 15-minute test flight today, and they all seemed at normal temparature. Do these test numbers seem normal? What else can I do to diagnose the state of my Phantom? I want to take all precautionery measures possible. Thanks

alokbhargava · Apr 2, 2016

First of all we thank you for publishing these numbers.

I was expecting deviations of about 2% max but I see about 10% from your readings. Can't comment on their validity.

Phantom works in a closed loop and adjusts rpm to what's needed for the desired operation. High deviations on two nearby motors will result into tipping over on ground.

Why were you even attempting to fly in such a strong wind that could roll it over?

alokbhargava · Apr 2, 2016

I will publish these numbers for my P3 possibly tomorrow when I return back home.

ullhan84 · Apr 2, 2016

alokbhargava said:
First of all we thank you for publishing these numbers.

I was expecting deviations of about 2% max but I see about 10% from your readings. Can't comment on their validity.

Phantom works in a closed loop and adjusts rpm to what's needed for the desired operation. High deviations on two nearby motors will result into tipping over on ground.

Why were you even attempting to fly in such a strong wind that could roll it over?

Exactly. Would never attempt flight on such conditions.

damirkotoric · Apr 2, 2016

alokbhargava said:
First of all we thank you for publishing these numbers.

I was expecting deviations of about 2% max but I see about 10% from your readings. Can't comment on their validity.

Phantom works in a closed loop and adjusts rpm to what's needed for the desired operation. High deviations on two nearby motors will result into tipping over on ground.

Why were you even attempting to fly in such a strong wind that could roll it over?

In hindsight I shouldn't have flown it. It was a client job, lots of pressure to deliver etc. I could've said no. Normally I'd never fly it in anything close to the winds that day.

Thank you. I'm curious to see what numbers you get

BudWalker · Apr 3, 2016

damirkotoric said:
A sudden gust of wind tipped over my Phantom 3 Professional while it was stationery on the ground. It carried the Phantom a couple of metres before it came to a stop. The propellers were in bad shape and afterward I hear a clicking / hissing sound from the motors during startup and shutdown. I decided to test the speed of the motors and here are the numbers:

I also checked the heat of the motors after a 15-minute test flight today, and they all seemed at normal temparature. Do these test numbers seem normal? What else can I do to diagnose the state of my Phantom? I want to take all precautionery measures possible. Thanks

Just curious. Do you know these numbers are actually RPM and not some other units? The reason I'm asking is that they look like the numbers found in the .DAT and I never got around to doing an actual measurement with an optical tachometer. For your purposes it doesn't really matter what the units are, but, if you've measured it then I'll document that in https://datfile.net/fields.html

DeeX · Apr 3, 2016

How do you test the motor's RPMs?

DeeX · Apr 3, 2016

Could you post RPM at full throttle with props on?

N017RW · Apr 3, 2016

You're worrying over nothing.

Go fly.

damirkotoric · Apr 3, 2016

BudWalker said:
Just curious. Do you know these numbers are actually RPM and not some other units? The reason I'm asking is that they look like the numbers found in the .DAT and I never got around to doing an actual measurement with an optical tachometer. For your purposes it doesn't really matter what the units are, but, if you've measured it then I'll document that in https://datfile.net/fields.html

Yes these are RPM units measured with the following tachometer: Digital Laser Photo Tachometer Non Contact RPM Tach Meter Motor Speed Gauge AU

damirkotoric · Apr 3, 2016

DeeX said:
How do you test the motor's RPMs?

damirkotoric · Apr 3, 2016

N017RW said:
You're worrying over nothing.

Go fly.

I can't argue against that logic

BudWalker · Apr 4, 2016

damirkotoric said:

You can also extract the motor speed data from the .DAT file which is internal to the P3. To see how to do that start here.

Since you've verified that those units are RPM I'll update the documentation.

BudWalker · Apr 4, 2016

damirkotoric said:
I can't argue against that logic

@N017RW gives good advice. The P3 does a pretty good job of testing the motors.The two burst sequence that occurs at motorStart provides speed and load data that the P3 (Advanced or Professional) evaluates to see if the motors are running properly. Any anomaly results in a shutdown and an ESC being reported. The P3 Standard can't do this test because it doesn't measure motor speed or motor load.

toegema · Apr 4, 2016

The P3 Standard also does that two burst seq upon engine start. Does it not test the motors then?

Sent from my iPhone using PhantomPilots mobile app

BudWalker · Apr 4, 2016

toegema said:
The P3 Standard also does that two burst seq upon engine start. Does it not test the motors then?

Sent from my iPhone using PhantomPilots mobile app

There may be other tests based on data besides the actual speed and load but I can't imagine what. Here is an example of a P3 Standard with a motor problem that isn't discovered during the motorStart two burst sequence. Take a look at the last paragraph in Standard - My first drone failure today.. Help!?!. Then take a look at the video IMG_0810[1_.mp4 (courtesy of @dg8882 )

damirkotoric · Apr 4, 2016

BudWalker said:
You can also extract the motor speed data from the .DAT file which is internal to the P3. To see how to do that start here.

Since you've verified that those units are RPM I'll update the documentation.

Wow! I had no idea. Thank you. I'll do this tomorrow.

damirkotoric · Apr 4, 2016

I just wanna say you guys are great helping me out here. The responses here have been really helpful, so thank you.

Moltar · May 6, 2016

This has been an extremely informative thread. Thank you to the OP and the subsequent commenters. I've been looking all over lately for some way to test the state of the motors on my P3A. I'm currently getting the .DAT files off my bird to review and graph the values. I just have one follow on question if I may:

Can someone please clarify for me (if possible) what the normal value ranges should be? I wasn't entirely clear on what those should be.

Many thanks to you all in advance. Also, an enormous kudos to the guys behind Datcon and everything on it. Really impressive work, mates.

MikeyOnline · May 6, 2016

Interesting that the two bursts on startup are to test the ESC's and motors. Makes sense. I wondered if they gave those two bursts to spin the props on a little tighter before takeoff.

BTW, I could have told him he's got a problem with that motor without the tach. Notice when he turns it off, the one that registered a lower RPM spun to a stop a lot faster than the other 3. That's one thing I look for each time I shut mine down: do all 4 motors come to a stop at pretty much the same rate? Granted, that won't detect all problems. But it's something.

Mike