My DJI Mini Pro reached speed of 15 miles per seconds within 3 seconds of launch and crashed that damaged camera gimble

[dealbelt]

Hi there,

I recently bought the DJI Mini Pro 3, and I attempted to hand launch it. However, within 3 seconds of launching, it suddenly accelerated at full speed of 15 miles in a random direction.

Unfortunately, it collided with a nearby trash can, resulting in damage to the camera gimbal.

Here is the link to my Airdata file:
I am seeking expert opinions to determine whether this incident was caused by my handling error or a system issue.

Thank you,

 

[Meta4]

I am seeking expert opinions to determine whether this incident was caused by my handling error or a system issue.

Your GPS was fine and had nothing to do with the incident.
Your incident was a result of a yaw error, caused by powering up where there was magnetic interference.
The data shows the drone starting out pointing just south of west with a heading of 257°, but you probably had it pointing somewhere else.
Do you remember which way the drone was pointing?

 

[dealbelt]

Your GPS was fine and had nothing to do with the incident.
Your incident was a result of a yaw error, caused by powering up where there was magnetic interference.
The data shows the drone starting out pointing just south of west with a heading of 257°, but you probably had it pointing somewhere else.
Do you remember which way the drone was pointing?

Thanks for your reply, I did standard pam launch, using NC remotes launch feature. Drone was flat on my hand and camera was facing me .

 

[Meta4]

Thanks again- that make me feel better, thanks god at least I followed basic instructions ( for minute I felt like a idiot)

If you had launched without waiting for GPS, that doesn't cause serious problems.
Your issue was caused when you powered up the drone, somewhere with magnetic interference from nearby steel or live electrical cables.
This caused the compass to read incorrectly.
The gyro sensor takes its initial directional value from the compass.
When the drone rises away from the magnetic influence, it returns to reading normally, but there is now a data clash between the compass and gyro and things quickly go bad.

 

[rwilliam99]

If you had launched without waiting for GPS, that doesn't cause serious problems.
Your issue was caused when you powered up the drone, somewhere with magnetic interference from nearby steel or live electrical cables.
This caused the compass to read incorrectly.
The gyro sensor takes its initial directional value from the compass.
When the drone rises away from the magnetic influence, it returns to reading normally, but there is now a data clash between the compass and gyro and things quickly go bad.

Would this case be an illustration of why it is important to verify the direction the drone is pointing in the map before taking off?

That was something I never really understood until I started reading this forum and now confirm it on every power up.

 

[slup]

...but there is now a data clash between the compass and gyro and things quickly go bad.

Just a small correction...

The data "clash" in itself isn't what causing the uncommanded flyaway during a yaw error. The real cause is that the Flight Controller have wrong info about in what direction the drone points & based on this wrong information (it got during power on from the deflected compass) command the wrong motors when the drone needs to hold position against outside forces like the wind for instance.

 

[dealbelt]

I cannot thank you and this community enough for providing me with quick responses.

Given the situation, I’m uncertain whether DJI will honor the warranty, Any idea?

 

[slup]

I cannot thank you and this community enough for providing me with quick responses.

Given the situation, I’m uncertain whether DJI will honor the warranty, Any idea?

If it was a yaw error caused by powering up the drone in magnetic interference it's a pilot error ... but DJI have sometimes taken the blame as a kind of goodwill. It's worth a try...

 

[Dave Maine]

Another note, a drone flying 15 miles per second would be supersonic. What you may have meant is 15 meters per second.

 

[Meta4]

What you may have meant is 15 meters per second.

It's max speed was 15 mph, but it would have seemed very fast because it accelerated to 15 mph from zero in just one second ... and then it crashed

 

[BudWalker]

Thanks for your reply, I did standard pam launch, using NC remotes launch feature. Drone was flat on my hand and camera was facing me .

"camera was facing me". But, what direction was it facing? We don't know the relative location of your eyes and hands so we can't tell which direction it was facing. Was it facing a little south of west as described by @Meta4 ?

When I first read this I thought obviously an incident caused by powering up at a geomagnetically distorted location. E.g. on a manhole cover or on concrete with rebar. But, now I'm not so sure.

There is minimal disagreement between locations computed by time integrating velocities (green path) and locations obtained from the FC (red path).

Usually these will be quite different if there is a heading error. Also looking at the AC tilt vs velocities it's at least plausible the heading is correct. A longer flight would help confirm this.

I noticed there are no stick inputs recorded and the pilot states that "NC remotes" was used to launch. Don't know what "NC remotes" is about. Is it some kind of automated launch that would be preferred in a hand launch? And, could the fault lie in the "NC remotes" execution?

 

[dealbelt]

I cannot thank you and this community enough for providing me with quick responses.

Given the situation, I’m uncertain whether DJI will honor the warranty, Any idea?

You're right, it was a handheld launch , and I didn't get a chance to react with the sticks. As soon as I launched the drone, it crashed. Normally, it's supposed to hover in the air. The more I think about it, the more I feel it might be some kind of system or software glitch.

 

[BudWalker]

You're right, it was a handheld launch , and I didn't get a chance to react with the sticks. As soon as I launched the drone, it crashed. Normally, it's supposed to hover in the air. The more I think about it, the more I feel it might be some kind of system or software glitch.

Please answer these questions
1. "camera was facing me". But, what direction was it facing? We don't know the relative location of your eyes and hands so we can't tell which direction it was facing. Was it facing a little south of west as described by @Meta4 ?

2. What does NC remotes mean

3. Did you provide any stick inputs? Any inputs to start motors? Any throttle input to cause it to lift from your hand?

 

[dealbelt]

Please answer these questions
1. "camera was facing me". But, what direction was it facing? We don't know the relative location of your eyes and hands so we can't tell which direction it was facing. Was it facing a little south of west as described by @Meta4 ?

2. What does NC remotes mean

3. Did you provide any stick inputs? Any inputs to start motors? Any throttle input to cause it to lift from your hand?

1) Drone was facing north west
2) I used DJI’s RC remote controller
3) I did not use stick input, the drone was launched using the launch push button from the RC app .

 

[Meta4]

1) Drone was facing north west

With the data indicating an initial heading just south of west at 257° and changing to 314° as the drone lifted, that supports the idea of magnetic interference causing the incident.

 

[BudWalker]

With the data indicating an initial heading just south of west at 257° and changing to 314° as the drone lifted, that supports the idea of magnetic interference causing the incident.

I'm still not convinced. The changing yaw at liftoff scenario only applies to magnetometer data. That's only available in the .DAT log file. The Flight Controllers heading data is reported in the .txt and will remain fixed while the magnetometer data changes to the correct value.

Differences between the FC location data and the locations computed by integrating the velocity data is usually a good indicator of incorrect magnetometer data. But, there was good agreement here.

Bottom line I'm not convinced that the launch site was geomagnetically distorted. But, I don't see another compelling explanation.