Motor speed issue--- Long post warning

[Jeff48920]

Sorry for the long post but I want you all to have the complete information

I have been flying a Phantom 2 Vision for more than 8 months and decided to upgrade to a plus v3. I received it yesterday and after unboxing, I did what I call a “static test” to make sure that all the controls were working properly. On the desk I powered up my controller, wifi extender and then the model. I started the iphone software and everything looked fine. Then, with propellers off, I wanted to check to see if I may have the problem with the ESCs without taking the shell apart.
I accelerated the motors to full throttle (full speed ascent) and held the throttle open for about 10 seconds. I did not hear any problems at full speed and so I released the stick and it returned to the center position. . . unfortunately the engines remained at full rpm as if I hadn't released the stick. I throttled down with the stick and the engines slowed although they did not appear to slow to idle speed.

Prior to attempting any flights, I called DJI and they first said they never heard of that issue, but suggested I do a do firmware update on both the model and the transmitter.
Reluctantly I updated from 3.08 to 3.12 (which I guess, for better or worse, makes me an early adopter). Everything else was up to date. (RC controller firmware 1.2) They then instructed me to do an advanced IMU calibration. I successfully did so this morning.

There is fundamentally no change to the issue described above with one negative exception. Now, once I throttle back down to as slow as the engines will go, they will, independently, change speed as if attempting to correct for GPS altitude input. The model is inside on my desk but has communication between 7 and 10 satellites.

I reentered the Phantom software and went to the "RC" tab in the "Basic" section. I repeated the holding of the stick in the accelerate position and the graphic showed the "A" stick in the proper position. I released the stick, expecting to see the cursor stay in the full right position, but it returned to the normal position, indicating that the motors are getting the proper command to slow back down.

I am at a loss. Has anyone heard of this? I am afraid to fly it in this condition unless this is a normal situation.
Thanks

 

[msinger]

Did you calibrate your remote controller after unboxing? If not, try this:

 

[Jeff48920]

msinger--- Thanks, my fault--- I should have said I also calibrated the RC and then calibrated the Phantom to the recalibrated RC

 

[RichWest]

I accelerated the motors to full throttle (full speed ascent) and held the throttle open for about 10 seconds. I did not hear any problems at full speed and so I released the stick and it returned to the center position. . . unfortunately the engines remained at full rpm as if I hadn't released the stick. I throttled down with the stick and the engines slowed although they did not appear to slow to idle speed.

This all sounds normal. With full throttle, without propellers, the motors continue to maintain whatever RPM required to maintain the perceived altitude. FWIW, the motor's RPM will reduce if you left it at full throttle for a minute, without stick input. Again the bird perceives it needs less RPM to maintain its current Altitude and will slowly reduces the RPM down to whatever above idle.

After this exercise, the motors will not return to an idle RPM. You'd need to stop the motors, just like you would on a typically landing. Once you restart the motor, then you should have the idle RPM you are wanting.

 

[N017RW]

These are very good points Rich and everyone needs to remember that once you start the motors, and add any throttle, the quad 'expects' to be flying.
Props, no props, inside, outside, with GPS, without GPS... you get the idea

 

[Jeff48920]

Rich and N017RW---
Thanks very much. I was hoping that was the fact but I may be just a bit gun-shy with the new bird. I was pretty comfortable with the Vision but I must admit I never tried this test with it....
Fly fast and thanks again for the assist!

 

[RichWest]

Your welcome, but give it a go to confirm for yourself. Nothing like first hand experiences....

 

[max]

I think I know the problem. it sounds like your propellers are the wrong type. Try using the stock propellers instead of the imaginary set. joking aside, just go fly the thing. I'll give you ten to one that it flies great and behaves "as expected" once you get it in the air.

Side note, be careful running full power for too long; the motors are designed to have a load present when running at speed.

 

[Meta4]

once I throttle back down to as slow as the engines will go, they will, independently, change speed as if attempting to correct for GPS altitude input. The model is inside on my desk but has communication between 7 and 10 satellites.

btw .. there is no GPS input for altitude.
GPS is very inaccurate for altitude.
Altitude comes from a barometric sensor.