A video I made where I seem to be getting some weird drifting from side to side when moving forward>
Is this the result of a warped Prop?

I think it could also be caused by optical-flow.

I’m afraid your wasting your time changing prop, it’s very clear that craft was drifting because of VPS and I’d safely say lack of gps, Vps will not work in low light and craft will drift just as yours has done. It also requires good textured and bright conditions on the floor.

If your compass needed calibration it would have prompted and same with IMU,

Only way you will stop it happening is to fly in ATTI mode which is not an option with mini.

hallmark007 Posted at 5-3 11:51
I’m afraid your wasting your time changing prop, it’s very clear that craft was drifting because of VPS and I’d safely say lack of gps, Vps will not work in low light and craft will drift just as yours has done. It also requires good textured and bright conditions on the floor.

If your compass needed calibration it would have prompted and same with IMU,

Hey Hallmark, thanks for the reply.
I thought you get a warning when VPS cant track properly or am i mistaken?
Also, if you go to 5:50 in the video, this is the location where it was at its worse, would you say the floor is too dark for VPS?
I have flown in lots of forested areas and its never been this bad.

SLiWooDy Posted at 5-3 12:04
Hey Hallmark, thanks for the reply.
I thought you get a warning when VPS cant track properly or am i mistaken?
Also, if you go to 5:50 in the video, this is the location where it was at its worse, would you say the floor is too dark for VPS?

You don’t get any warning, I have tried these under bridge fly through and they are very difficult because of no gps or low gps and no vps, you may get different parts of the day light is shining through forest or under archway this will help, testing this is easy enough you can do it under normal light out in the open, if you still have drifting then it’s more likely your IMU needs calibration .

I seem to be getting some weird drifting from side to side when moving forward>
Is this the result of a warped Prop?

There's nothing weird about what you are experiencing.
Normally, I want to see the flight data before guessing.
But in this case it's obvious that flying in that tunnel you have:
  No GPS
  No VPS
That leaves your drone in atti mode with no horizontal position holding stability and subject to drifting with air currents.
All the conjecture about propellers, compass or IMU is pointless.
Any other DJI drone would have the same issue.

In the forest, GPS will have been affected, the flight data will confirm how much and it's possible that the ground surface was unsuitable for VPS.

This is Drone 101, not rocket surgery.
If you want to check, try flying the drone in a suitable environment out in the open and it will fly perfectly, proving that none of those guesses were valid.

Am I correct in thinking that a Mavic Air 2 would have the same problems, sans side sensors? Or would side sensors never come into play anyway?

GaryDoug Posted at 5-3 18:53
Am I correct in thinking that a Mavic Air 2 would have the same problems, sans side sensors? Or would side sensors never come into play anyway?

Any other DJI drone would have the same issue.
Sensors are no help when the drone lacks the ability to hold position.
It's like driving on smooth ice .. there are no brakes.

That doesn't seem anything like a warped prop but normal behavior. For what I have seen bigger Mavics are better at thins kind of activity, with probably the Phantom family being the best.

Anyway... if you'd ask me, I'd try A) not to do anything like that, B) in case I really need to use prop guards (not necessarily the Fly more bundled cage) C) try to replace that footage with a camera on a Steadycam and similar or other stabilized electronic gimbals.

Labroides Posted at 5-3 15:30
I seem to be getting some weird drifting from side to side when moving forward>
Is this the result of a warped Prop?

Going through the tunnel I accept there would be no GPS, as I say in the video, but through the trees we had 14 Satalites showing.
I have flown countless times through forested areas and its never been this bad.
Plus the fact that we visiually inspected the propellers after returning home and one of the rear props was visibly warped/flat after removing it (not guessing), this would have a bearing on the flight of the drone no?

SLiWooDy Posted at 5-3 21:19
Going through the tunnel I accept there would be no GPS, but through the trees we had 14 Satalites showing.
I have flown countless times through forested areas and its never been this bad.
Plus the fact that we visiually inspected the propellers after returning home and one of the rear props was visibly warped after removing it (not guessing), this would have a bearing on the flight of the drone no?

You'll never solve the mystery by guessing.
If you want to test your theory properly, you'd have to test fly in the open with the same propellers.
And then test where the problems were observed but with new props.
If new props fix the issue (they almost certainly won't), that points to props being involved.

And examine the flight data to see what it says rather than what you think was happening.
Post the .txt files for tunnel + forest flights so we can see how the flight controller rated the GPS Health.

Labroides Posted at 5-3 22:26
You'll never solve the mystery by guessing.
If you want to test your theory properly, you'd have to test fly in the open with the same propellers.
And then test where the problems were observed but with new props.

I not sure where you getting this "guessing" from.
If I can visually see that one of the rear props is flat/warped compared to the other 3 are you suggesting that I fly with it?

SLiWooDy Posted at 5-3 22:32
I not sure where you getting this "guessing" from.
If I can visually see that one of the rear props is flat/warped compared to the other 3 are you suggesting that I fly with it?

I not sure where you getting this "guessing" from.
You've noted that one prop looks a little different and made the assumption (that's a guess) that is the cause of the issue.
But you haven't done anything to confirm whether your guess is at all accurate.
I've pointed out how you could ... but you don't seem to be interested.

I have pointed out other factors which are much more likely to have been responsible.
If you like, you could call them my guesses.

So .. which guesses (if any) are correct?
Unless you test to confirm one way or the other, you are simply making a guess and assuming it's correct.
That's hardly scientific.

Start by posting the flight data which will show how good GPS really was in the forest.

SLiWooDy Posted at 5-3 22:32
I not sure where you getting this "guessing" from.
If I can visually see that one of the rear props is flat/warped compared to the other 3 are you suggesting that I fly with it?

Although there is a visual difference, we do not know what the tolerances are and how much impact this has on flight characteristics and the response of the motor speed. One way to demonstrate this has impact would be to swap back and forth the props between the different batches and see if you can consistantly trigger the issue with the "flattened" ones, preferably with looking at the DAT file graph on top of that.

GaryDoug Posted at 5-3 18:53
Am I correct in thinking that a Mavic Air 2 would have the same problems, sans side sensors? Or would side sensors never come into play anyway?

MA2 has APAS so wouldn’t move straight but likely zig zag but avoid obstacles but it still like other drones needs sufficient light.

SLiWooDy Posted at 5-3 21:19
Going through the tunnel I accept there would be no GPS, as I say in the video, but through the trees we had 14 Satalites showing.
I have flown countless times through forested areas and its never been this bad.
Plus the fact that we visiually inspected the propellers after returning home and one of the rear props was visibly warped/flat after removing it (not guessing), this would have a bearing on the flight of the drone no?

If you walk straight through the forest with the drone held above your head set it to record, you’ll get the same shot ;+):::. Seriously this is a gps vps problem and that’s what’s causing drone to continue to veer, you may get lucky at times with sensors being intermittent.
You said the prop was warped, did you crash ? That could cause craft to veer because IMU is out of calibration. But the simple test is out in the open fly a straight line compare logs and you know.

SLiWooDy Posted at 5-3 22:23
[view_image]

That could well be the reason for the high motor speeds (read from 16,000 here). Screw the flattened parts on and show us what the motor speed does.

DaMa Posted at 5-4 01:47
That could well be the reason for the high motor speeds (read from 16,000 here). Screw the flattened parts on and show us what the motor speed does.

Sorry,  just seen your post. I have binned the old props.
In hindsight I should have tried to investigate the issue and tried to narrow down what was the cause. It was strange that only one prop seemed FLAT..
But I replaced all the rear props and re-calibrated the IMU.
I took the drone back this morning to the exact location and tried it again with these changes, I am just putting the video together now. But lets just say it was like a different drone.

To some of the other replies above, do you really think this is my first time flying through a tunnel or forested area?
Do you think I have never flown a drone without losing GPS?
Do you think that I have never flown a drone without VPS?
Do you think that I have never flown a drone in Atti mode?

SLiWooDy Posted at 5-4 05:09
Sorry,  just seen your post. I have binned the old props.
In hindsight I should have tried to investigate the issue and tried to narrow down what was the cause. It was strange that only one prop seemed FLAT..
But I replaced all the rear props and re-calibrated the IMU.

It's pretty clear that you have no interest in testing your guesses to see if they were correct.
You started the post with a question but won't consider any alternative proposal or testing to confirm one way or the other.

SLiWooDy Posted at 5-4 05:09
Sorry,  just seen your post. I have binned the old props.
In hindsight I should have tried to investigate the issue and tried to narrow down what was the cause. It was strange that only one prop seemed FLAT..
But I replaced all the rear props and re-calibrated the IMU.

No, I duck in discussions like this. I suspected the high speeds of the motors by the different play between screw and propeller. Then I brought my propellers to 0 play (minimum + speed change only for the propeller with the largest game (front right)). Responsiveness maybe a little "crisp" but not worth mentioning.
When I see that some have an motor running at 16,000 rpm and the rest at 10,000-12,000 rpm and the thing can still be landed, that's strange. I can only see a stall through fluttering blades or less buoyancy through flattened blades.
My MM swallows all my nasty things without complaining ... I also varnished him colorfully - he also likes it ...

SLiWooDy Posted at 5-4 05:09
Sorry,  just seen your post. I have binned the old props.
In hindsight I should have tried to investigate the issue and tried to narrow down what was the cause. It was strange that only one prop seemed FLAT..
But I replaced all the rear props and re-calibrated the IMU.

The fact you hadn’t a clue about what caused your problems, the answer to all of your questions is YES.
You hadn’t a notion it was anything to do with VPS no clue about calibration because you never mentioned IMU only compass , the fact the you totally ignore the fact that flying under cover of both bridge and trees would effect GPS.
You then mention ATTI if you were proficient your craft wouldn't  be flying like a three legged donkey.
You calibrated IMU, I guess that’s because it was mentioned above.
I agree with labroids , and I think you got enough information to get by.

But it was clear that a simple straight flight in the open would have confirmed if it was a prop as you suggested or what was staring you in the face.

hallmark007 Posted at 5-4 07:05
The fact you hadn’t a clue about what caused your problems, the answer to all of your questions is YES.
You hadn’t a notion it was anything to do with VPS no clue about calibration because you never mentioned IMU only compass , the fact the you totally ignore the fact that flying under cover of both bridge and trees would effect GPS.
You then mention ATTI if you were proficient your craft wouldn't  be flying like a three legged donkey.

OK lets get this right:
every time I have flown in a environment that is too dark. I get a VPS warning on the screen stating its too dark.  Which i didn't get in this flight.
GPS is clearly mentioned in the video when flying through the tunnel, Saying that I would lose it.
I had 14 Satellites and no warnings of  Weak GPS signal when flying through the Forest.
If I have GPS then ATTI mode isn't active.
I had no compass or IMU warnings, but at the 6:20 mark in the video I say that I will re-calibrate everything that can be re-calibrated. (that includes the IMU)
So I hope that clears a lot of the confusion up for both you and Labroides.

SLiWooDy Posted at 5-4 07:36
OK lets get this right:
every time I have flown in a environment that is too dark. I get a VPS warning on the screen stating its too dark.  Which i didn't get in this flight.
GPS is clearly mentioned in the video when flying through the tunnel, Saying that I would lose it.

I think you need to go back and see what you wrote including your heading, and failure to show log leaves everything open to discussion or not,  it seems you asked a question but you had already decided what the answer was, so a bit selfish because because nobody learns anything from this kind of post.
You also posted on 27/04 that you changed all props for improved better ones from dji,

hallmark007 Posted at 5-4 07:45
I think you need to go back and see what you wrote including your heading, and failure to show log leaves everything open to discussion or not,  it seems you asked a question but you had already decided what the answer was, so a bit selfish because because nobody learns anything from this kind of post.

For you and anyone else  that would like the answers:

SLiWooDy Posted at 5-4 08:09
For you and anyone else  that would like the answers:

https://youtu.be/fxHpkUgUPsA

One thing I do see is the sun could be clearly seen coming through the trees and it was completely brighter, whether that made any difference I don’t know but put the logs up and we will know, if not we won’t.

You might answer the question regarding props, you wrote on 27/04 that you got new props they felt much better and you replaced all props on your drone, what went wrong and had you flown since 27th did you not notice , considering you strong relationship with your drone, ;+) ,, or how did the much improved props become warped ?

SLiWooDy Posted at 5-4 08:09
For you and anyone else  that would like the answers:

https://youtu.be/fxHpkUgUPsA

Need to retry the tunnel flight with new props.  Preferably when wind conditions and sun light are close as possible to original flight.

If by chance you know which of bad props (matched set of blades) came off which motor, and can put them back on; repeating tests with bad props on and then new props on same day would be best.

hallmark007 Posted at 5-4 08:20
One thing I do see is the sun could be clearly seen coming through the trees and it was completely brighter, whether that made any difference I don’t know but put the logs up and we will know, if not we won’t.

You might answer the question regarding props, you wrote on 27/04 that you got new props they felt much better and you replaced all props on your drone, what went wrong and had you flown since 27th did you not notice , considering you strong relationship with your drone, ;+) ,, or how did the much improved props become warped ?

I already had the props in the fly more combo. I have never crashed my Mini.
I also have not changed my props, these were the original ones that were on it since purchase. (can you show me where i said I have changed my props?)
But I have crashed a lot of RC helicopters. LOL
The rear props on the drone about 1 week ago just felt a little more flexible than a set of new props.
I personally believe (and this is only my opinion) that the props are to thin and not stiff enough.

Next time its sunny/warm in the UK I  am planning on leaving one out in the Sun to see if the heat affects them and flattens them.

HedgeTrimmer Posted at 5-4 08:49
Need to retry the tunnel flight with new props.  Preferably when wind conditions and sun light are close as possible to original flight.

If by chance you know which of bad props (matched set of blades) came off which motor, and can put them back on; repeating tests with bad props on and then new props on same day would be best.

Hey HEdgeTrimmer, Unfortunately the old props are long gone in the bin.
This was never really meant to be an investigation into drone.
It started as a "Behind the Scenes" of a Cinematic Video using the Mavic Mini,
But as I was filming, the drone seemed to be getting less and less stable with more erratic behaviour.
I concluded the video with what I thought was the cause of the problem and folk have jumped on it.

I wasn't planning on going back to the Forest to repeat the video just yet as its a fair way from my House. But after reading some of the comments, I thought it only fair that I go back and see if the drone really is more stable after a prop change and IMU re-calibration.
The flight you see in the second video is literally the first time the drone took off after the changes and it managed to fly the route on the first take with no issues at all.
The day previous  (in very similar conditions, albeit not exactly) I couldn't get the drone more than 10meters without it pitching to one side.

The Tunnel is approx 1mile further down into the forest and would have been great to repeat!
But with so many variables, and admittedly the environment is never exactly the same,
It couldn't really be called a repeat test. Plus like I say the props are long gone in the bin.
If I get chance to visit the location again I will be sure to try it again!

Safe flying!

Yes, Jump all over somebody for at LEAST TRYING to help; whilst giving DJI a pass for doing NOTHING to help...

Nothing in FW update notes about possibility of bad prop warnings.  
No sticky on MM page to make up for missing FW notes.
No notices from DJI in regards to replacing bad props, still getting a warning, and possibility spare blades were also bad.
Nothing from DJI asking for suspect bad props to be sent back for QA testing.

PS: Nothing against the OP.

SLiWooDy Posted at 5-4 08:09
For you and anyone else  that would like the answers:

So I hope that clears a lot of the confusion up for both you and Labroides.
I'm not at all confused.
It's perfectly clear that you encountered a situation that puzzled you, asked a question, guessed an answer, did a bunch of things that may or may not have addressed the actual issue and have no interest in finding out what the issue was or even if there really was an issue.

For you and anyone else  that would like the answers:
Answers?  What answers?
You've blatantly ignored all questions and made no effort to confirm the cause of your incident.
You have no answers and you aren't interested in finding any.

A lot of people were saying that you didn't know what you were talking about, that it was a sensor or GPS issue.
Correction.
Someone suggested that it probably wasn't what you guessed and suggested alternative explanations as well as ways to identify the actual cause of the issue.
But you had made up your4 mind without any evidence and have no interest in confirming whether your guess was correct or not.

The point that you still don't get is that the recorded flight data shows exactly what is happening for every 1/10th of a second of the flight so you don't have to guess.
It doesn't matter if you've flown through tunnels hundreds of times, what's important to answer the question you asked, is to see what happened during that particular flight.

There's still something clearly wrong ... despite your vast experience flying in tunnels, you have very little understanding of how your drone works.
This is demonstrated by you unnecessarily recalibrating your compass and IMU without any idea that they were a problem (they almost certainly weren't).

You haven't proved anything.
Rather than "trusting your gut instinct", landing the drone, changing props, recalibrating things that and assuming that fixes things, the way to solve flight mysteries is to identify the cause of the incident so that you can do what's necessary to fix the actual cause of the incident.

I'd hate to be paying a mechanic with your ignorance and attitude to work on my car.

Labroides Posted at 5-4 14:46
So I hope that clears a lot of the confusion up for both you and Labroides.
I'm not at all confused.
It's perfectly clear that you encountered a situation that puzzled you, asked a question, guessed an answer, did a bunch of things that may or may not have addressed the actual issue and have no interest in finding out what the issue was or even if there really was an issue.

This is Drone 101, not rocket surgery,
Stay Awesome Labroides.

SLiWooDy Posted at 5-4 23:42
This is Drone 101, not rocket surgery,
Stay Awesome Labroides.

It's Willfully Ignorant Guessing 101, with no intention of ever improving or finding facts.
Hardly the best way to improve your droning.

Labroides Posted at 5-5 01:50
It's Willfully Ignorant Guessing 101, with no intention of ever improving or finding facts.
Hardly the best way to improve your droning.

You really are beginning to boring me now.
If you want to go and create a post about how people should go about finding errors/faults with their drones go do it.
My drone is flying perfectly fine now thank you, even with my "guessing".

SLiWooDy Posted at 5-5 02:54
You really are beginning to boring me now.
If you want to go and create a post about how people should go about finding errors/faults with their drones go do it.
My drone is flying perfectly fine now thank you, even with my "guessing".

Maybe it was flying perfectly before, but since you refused to look into it, you'd have no idea.

Labroides Posted at 5-5 03:31
Maybe it was flying perfectly before, but since you refused to look into it, you'd have no idea.

And you're still boring me.