Crashed - now P3P flips on takeoff

KilroySmith · Jan 28, 2019

I'm pretty much a noob with my P3, but am an engineer in real life.
I crashed my P3Pro after a number of great flights, and am trying to get it flying again.
I've run the IMU calibration, which completes successfully. The sensor status screen looks fine to my eyes. I've run the camera calibration which completed successfully.

I have two current problems:
1. On liftoff, the props spin up and the drone starts rising (yay! Its working!) but at about 0.5m, it executes a quick 180 degree flip upside down then drives itself into the ground (oops). Any thoughts on where to look for the problem, or perhaps determining how to start diagnosing it?
2. On the ground, the camera gimbal vibrates every second or two (grind.....grind...grind). I noticed today that one of the rubber vibration isolators is ripped and so the camera isn't flat; is that likely to cause this issue? I notice that if I rotate the camera down to about 45 degrees, the vibration stops.

Any help would be much appreciated,

quaddamage · Jan 30, 2019

1. Assuming you have CW and CCW propellers at correct motors, the issue would be either with IMU or ESCs - ie. the solder may be teared and vibrations cause loss of connection. Check flight logs to get details.

2. That is unrelated to 1st issue. Probably physical damage to gimbal: potentiometer broken, motor magnet fractured or flat film wire damaged.

Nightwolf · Jan 30, 2019

try going a little higher right away. You may be causing a vortex that close to the ground

MotorCycle-Man · Jan 30, 2019

quaddamage said:
1. Assuming you have CW and CCW propellers at correct motors, the issue would be either with IMU or ESCs - ie. the solder may be teared and vibrations cause loss of connection. Check flight logs to get details.

Because of the different threads on the motors.....Its impossible to attach a wrong prop to a motor......However in a repair you can replace a CCW motor with a CW motor and have problems !

quaddamage · Jan 30, 2019

MotorCycle-Man said:
Because of the different threads on the motors.....Its impossible to attach a wrong prop to a motor.....

Oh, you are very wrong. But I must say, I was very surprised as well the first time I saw that. It turns out man can often make up lacks in brains with physical strength.

KilroySmith · Jan 31, 2019

So, not having applied excessive force, let's assume that I have the props in the right place.

I can't go higher - I'm using the auto-liftoff feature and the flip is occurring while the drone is in the process of climbing to it's normal 1.2m altitude. Total flighttime is about 2 seconds.

Is there a good description somewhere of how to check the flight logs? I've run across bits and pieces, but if anyone has a link to the "idiots guide to acquiring, processing, and reading the flight logs" it'd make my job easier.

Looking closely, it appears that there is damage to the gimbal flat cable. Guess I'll put one of those on the shopping list also...

Nightwolf · Jan 31, 2019

KilroySmith said:
it appears that there is damage to the gimbal flat cable

Make sure you get an OEM cable. There are countless stories of cheap cables not working. It's a job you don't want to do twice

Flight logs:
Upload Here: DJI Flight Log Viewer | Phantom Help
post the resulting URL back here

MotorCycle-Man · Feb 1, 2019

quaddamage said:
Oh, you are very wrong. But I must say, I was very surprised as well the first time I saw that. It turns out man can often make up lacks in brains with physical strength.

Quad that had to be a heck of a terrible struggle to get a CCW prop on a CW thread....Id love to see a video of that being done How about You LOL...that prop had to wobble bad too.

quaddamage · Feb 5, 2019

MotorCycle-Man said:
Quad that had to be a heck of a terrible struggle to get a CCW prop on a CW thread....Id love to see a video

It wasn't hard to find one:

MotorCycle-Man · Feb 5, 2019

Thanks Quad......i seen it and hard to believe it CAN be Done...One of the mods here said it could not be done.....thats Y i said that !
You are really supposed to watch the prop end colors and properly match them with the color on end of the engine shaft and all will Sure will Be hunkey Dorey !

And i seen in the video it was by nigel "solentlife" a member here.

RodPad · Feb 26, 2019

@KilroySmith,
Did you figure anything out?

Have somebody hold it start the motors manually see if you can get more than your 2 seconds out of it. Or you can tie it down to a milk crate, etc.

If you get your flight logs, @Nightwolf's link. Simplest is off the mobile device and share them here others will be to help you out.

Rod

xspwhite · Feb 26, 2019

I would probably run it on a work bench with not props, and watch and listen to what the motors are doing or not doing.

RodPad · Feb 26, 2019

xspwhite said:
I would probably run it on a work bench with not props, and watch and listen to what the motors are doing or not doing.

Yes, but I recall that at some point in firmware, the Phantom senses no props and shuts down, give it a try.

There was a guy, that we were helping, he said the motors wouldn't stay on, even with Auto take off, we finally figured out he hadn't put the props on yet.

Rod

RodPad · Feb 26, 2019

Hum, well I think this was the thread.
Standard - Help Motors won't start

Rod

RodPad · Feb 27, 2019

After reading that thread, it appears that maybe that will only happen on auto take off.

Rod

MotorCycle-Man · Feb 27, 2019

xspwhite said:
I would probably run it on a work bench with no props, and watch and listen to what the motors are doing or not !

CAUTION: I have read it here on this PP forum : Never EVER run the drones motors at FULL SPEED with > NO props < as you put undue wear on the " teeny tiny itsy bitsy " small ball bearings !

xspwhite · Feb 28, 2019

Short burst test should be ok. I didnt mean for him to put them on full crank, and go make a sandwich. Just do some small take off simulations and put an ear to each motor, and maybe feel them for heat. But if the drone is just going to shut down, then it may not work.

With The Birds · Feb 28, 2019

xspwhite said:
Short burst test should be ok. I didnt mean for him to put them on full crank, and go make a sandwich. Just do some small take off simulations and put an ear to each motor, and maybe feel them for heat. But if the drone is just going to shut down, then it may not work.

Can be as long of a burst as you might like with no fear of damage.

MotorCycle-Man · Feb 28, 2019

Justy what is the FULL BORE Wide Open Rpm's of a drone motor....." With props " and with " No props " ?

With no props How in the whole world could you measure the speed ? there's a small meter that we use on R C planes to check the props speed....it reads the light between the spinning prop and divides it in half for the RPM reading.

With the birds..You actually mean with no props i could use a 100% charged battery and run the motors with No Props to 30 % or Less battery ?
Man some things got to..... Blow up

.... Burn UP

..... or..... self destruct

With The Birds · Feb 28, 2019

MotorCycle-Man said:
Justy what is the FULL BORE Wide Open Rpm's of a drone motor....." With props " and with " No props " ?

With no props How in the whole world could you measure the speed ? there's a small meter that we use on R C planes to check the props speed....it reads the light between the spinning prop and divides it in half for the RPM reading.

With the birds..You actually mean with no props i could use a 100% charged battery and run the motors with No Props to 30 % or Less battery ?
Man some things got to..... Blow up.... Burn UP..... or..... self destruct

What you might not be allowing for is that the throttle doesn’t command motor speed directly and certainly not in proportion to the applied stick defection. Movements of the throttle stick from the centre detent are interpreted by the flight controller as an intention to increase or decrease altitude. Sitting on the ground moving the stick fully up the flight controller will apply power to the motors but will quickly detect an issue when no thrust is detected (the phantom doesn’t move). Even the flight controller didn’t do this the maximum RPM of the motors is determined by the ESC.. I can’t run faster than the max drive frequency set in the parameters flashed to the ESC SOC even unloaded. The motor won’t be taken outside it’s safe max RPM or thermal limits- winding current is obviously low when not required to drive a propellor.