Phantom 3 out of control at 81 mph and no wind!

[Adam Herron]

I didnt want to hijack someone thread but I just wanted to share this, I was taking video of fireworks near the lake, The first battery went fine, but the second battery just went crazy after launch with compass errors and such. After a big fight with it, I managed to get it back in one piece without going into the lake. If someone could just take a look at the log and let me know what happened. Thanks.

81.83 mph is that some kinda record?!

 

[losman26]

Phantom Log Viewer - PhantomHelp.com
take a look there.

I'm no expert, but you had something similiar to what happened to me. Speed error, compass error, yaw error, voltage dropping.

You extremely lucky to have yours back. Mine is gone, and someone is probably selling the parts somewhere.

 

[Numone]

I really think there is some flaw in there.. How could it possibly go from, to and back to these speeds in .5 of a second..
27.0s 21.1mph
27.1s 47.4mph
27.2s 12.9mph
27.4s 28.2mph
27.5s 42.2mph

 

[losman26]

I really think there is some flaw in there.. How could it possibly go from, to and back to these speeds in .5 of a second..
27.0s 21.1mph
27.1s 47.4mph
27.2s 12.9mph
27.4s 28.2mph
27.5s 42.2mph

maybe a motor shutting on and off.

 

[losman26]

If I were you, I'd send your phantom to be looked at, because next time you'll probably lose it. Did you take a video?

 

[Adam Herron]

If I were you, I'd send your phantom to be looked at, because next time you'll probably lose it. Did you take a video?

No i didnt take a video. It was already dark and I was more worried about getting it back. I kept doing circles till i could figure out what way i had to go to get it to come back my way.

 

[losman26]

No i didnt take a video. It was already dark and I was more worried about getting it back. I kept doing circles till i could figure out what way i had to go to get it to come back my way.

man, you are extremely lucky. Like I said, I lost mine in a similar situation.. Wish I was going over water, because maybe I wouldn't have lost my RC signal.

 

[Numone]

maybe a motor shutting on and off.

I was thinking there's more of a flaw in the accuracy of the data. It'd be simply impossible for a phantom to accelerate 26mph in a 10th second. That would be almost 10x faster than the fastest accelerating car in the world.

 

[Vertigo]

The phantom doesnt have an airspeed sensor, it derives its speed from GPS location, and is therefore prone to error. Far more worrying about the logs is the battery voltage. You took off with a full battery and 30 seconds in to the flight, you reach critically low voltages. It recovers later, but something must have been drawing excessive current. Ive seen this before, I dont know what causes it, but the high currents could explain the compass errors.

 

[Numone]

The phantom doesnt have an airspeed sensor, it derives its speed from GPS location, and is therefore prone to error. Far more worrying about the logs is the battery voltage. You took off with a full battery and 30 seconds in to the flight, you reach critically low voltages. It recovers later, but something must have been drawing excessive current. Ive seen this before, I dont know what causes it, but the high currents could explain the compass errors.

Aware of that, my point is I've never seen deviations like that before. Great point on the battery voltages Vertigo. What could pull that amount of additional current on the Phantom?

 

[maxwell smart]

Wow very lucky. First thin I would not use that battery any more. I had a compass error once ,and it was very hard to get it back.
May be someone was using some strong radio or wifi equipment. On the water ,for boat traffic? You should test fly it after compass cal.
But stay close and see if it is OK.

 

[Vertigo]

Aware of that, my point is I've never seen deviations like that before. Great point on the battery voltages Vertigo. What could pull that amount of additional current on the Phantom?

Motors are the obvious culprit, nothing else on a phantom should draw anywhere close to that amount of power. Ive seen some reports where people also said their phantom sounded weird, with a high pitch noise. This could indicate an ESC syncronization error. Im not sure that would explain the high current draw, or if rather it points to the same root cause, like bad motor (damaged bearing or whatever).

 

[Adam Herron]

Wow very lucky. First thin I would not use that battery any more. I had a compass error once ,and it was very hard to get it back.
May be someone was using some strong radio or wifi equipment. On the water ,for boat traffic? You should test fly it after compass cal.
But stay close and see if it is OK.

 

[BudWalker]

I really think there is some flaw in there.. How could it possibly go from, to and back to these speeds in .5 of a second..
27.0s 21.1mph
27.1s 47.4mph
27.2s 12.9mph
27.4s 28.2mph
27.5s 42.2mph

These speeds are calculated by the .txt converter that was used. A more accurate picture of the speed can be obtained by using the speed calculated by the P3 and written to the .txt file.

@Adam Herron would it be possible for you to retrieve the .DAT and post it via a Dropbox link. Look here to see how to retrieve the .DAT. I'm interested in the compass error encountered in your flight and the relevant data will be in the .DAT.

 

[Adam Herron]

I will test it out with no one around around just to try and eliminate any other problems. I was in a hurry to get back up there and finish the fireworks. But im almost 100 percent positive that there was no compass error when I took off the second time. As for the deviations in the speed, i remeber looking at the camera and i could see the landing gear it was flying so fast. Thanks everyone for your help.

 

[Adam Herron]

These speeds are calculated by the .txt converter that was used. A more accurate picture of the speed can be obtained by using the speed calculated by the P3 and written to the .txt file.
View attachment 59098
@Adam Herron would it be possible for you to retrieve the .DAT and post it via a Dropbox link. Look here to see how to retrieve the .DAT. I'm interested in the compass error encountered in your flight and the relevant data will be in the .DAT.

Sure i will post it to my dropbox in a few minutes

 

[BudWalker]

Dropbox - FLY195.DAT

Here is the .DAT file. Thanks for your help!

Thanks, but that isn't the right .DAT. There isn't a motorStart in this .DAT. The .DAT retrieval instructions here has a paragraph at the end of the page about determining which is the right .DAT.

 

[Adam Herron]

Thanks, but that isn't the right .DAT. There isn't a motorStart in this .DAT. The .DAT retrieval instructions here has a paragraph at the end of the page about determining which is the right .DAT.

Alright sorry about that, Uploading the correct one now.

 

[Adam Herron]

Dropbox - FLY194.DAT That is the correct one I think.
Thanks @BudWalker

 

[Vertigo]

I had a closer look at the original log. First thing that struck me, somehow it measured negative amps/watts right at the moments that the voltage sagged badly:

Im not even going to attempt to explain that.