120ccpm Posted at 5-1 09:28
I wish they would of started a new thread to discuss how drones fly but what can you do, no one seems to care about the actual research going on.

A bit of an unfair comment... yes, this discussion is a bit off-topic, but it's related to motor speeds, and how drones adjust those to move around. If you think about it, they have no ailerons, no elevators, no rudders, no swashplates, no variable pitch... they move through the air by "simply" adjusting the SPEED of 4 motors. There is nothing else they control.

You wrote ''I would add, so far it's been a very amicable exchange of opinions, polite tones, that's how forums should always be.''



Re:  '' Not convinced ? ''

No, sorry. Let me draw what I see it in my head.  Maybe I'm wrong and if so, I will be the first one to admit.  Une image vaut mille mots (1000 words)

See you later !

hallmark007 Posted at 5-1 10:15
I think thread showed for those who tested props motor discrepancies in using different props and testing out at different speed and altitude, there is also 2/3 other threads where others have also tested, but one thing I have noticed with all the testing and discrepancies we have not seen one craft involuntary descend either have we seen any other user reporting involuntary descent since last FW on this forum, and if we match warnings , your testing , and the fact that warnings have been bypassed and the fact we know that discrepancies are showing up, then why are we seeing no drop outs involuntary descents, if your testing discovered so many discrepancies “with props” why are we not seeing a lot more descents ?

I think simply because these RPM tests, as well as the Motor Error warning, detect prop issues before they get severe enough to trigger an uncommanded descent. Several users have reportedly replaced props, and the Motor Error went away. If everybody follows the recommendation and replace the offending props, I'd say there's a good chance that we won't see any more uncommanded descents.

120ccpm Posted at 5-1 10:23
I think simply because these RPM tests, as well as the Motor Error warning, detect prop issues before they get severe enough to trigger an uncommanded descent. Several users have reportedly replaced props, and the Motor Error went away. If everybody follows the recommendation and replace the offending props, I'd say there's a good chance that we won't see any more uncommanded descents.

I agree. And keep in mind, the warning is above where any of our RPMs have been. I have never had an error or warning. If you get a FW warning, then replace the props. Unfortunately, some will do an RPM test, see variance, replace their props, and replace a known perfectly fine prop with an unknown crappy one.

120ccpm Posted at 5-1 10:23
I think simply because these RPM tests, as well as the Motor Error warning, detect prop issues before they get severe enough to trigger an uncommanded descent. Several users have reportedly replaced props, and the Motor Error went away. If everybody follows the recommendation and replace the offending props, I'd say there's a good chance that we won't see any more uncommanded descents.

You completely missed my point, all tests were done stating props were bad and many users just bypassed replacing props and most received no warnings. If your advice is that props are bad and causing all involuntary descents, remember all tests showed “ bad props”  But all tests equally showed no drops in altitude and no involuntary descents, and if you take into consideration those who updated through assistant so unlikely to get warning to change props , that we would have seen at least one person reporting drops in altitude or worse drone lost from involuntary descent.

You must remember that if we look at the tests and take what we have seen literally, then 100% of drones tested showed discrepancies, not one passed all had some problems, so that would or should translate into all Mavic mini having prop discrepancies, so chances are pretty good if props ONLY are causing craft to descend, then we should see many many more very very soon dropping from the sky or land going backwards.

hallmark007 Posted at 5-1 10:46
You completely missed my point, all tests were done stating props were bad and many users just bypassed replacing props and most received no warnings. If your advice is that props are bad and causing all involuntary descents, remember all tests showed “ bad props”  But all tests equally showed no drops in altitude and no involuntary descents, and if you take into consideration those who updated through assistant so unlikely to get warning to change props , that we would have seen at least one person reporting drops in altitude or worse drone lost from involuntary descent.

You must remember that if we look at the tests and take what we have seen literally, then 100% of drones tested showed discrepancies, not one passed all had some problems, so that would or should translate into all Mavic mini having prop discrepancies, so chances are pretty good if props ONLY are causing craft to descend, then we should see many many more very very soon dropping from the sky or land going backwards.

I think he is talking about the FW warning, not just an RPM discrepancy, and none of the props tested here were triggering an FW warning, unless I missed something. I know mine weren't. HedgeTrimmer once said that some props might be exceptionally thin from the factory, which is plausible. In fact, anything that might only affect less than 1% of the users is plausible, and anything that would affect all of the users is implausible. We are dealing with an issue that has affected far less than 1% of the users, so it cannot be an issue that affects all of the users. Lol, but that ain't going to stop some people from continuing to look for issues that affect all of the users. I suspect there will be a few more case mods.

Deucalion Posted at 5-1 10:55
I think he is talking about the FW warning, not just an RPM discrepancy, and none of the props tested here were triggering an FW warning, unless I missed something. I know mine weren't. HedgeTrimmer once said that some props might be exceptionally thin from the factory, which is plausible. In fact, anything that might only affect less than 1% of the users is plausible, and anything that would affect all of the users is implausible. We are dealing with an issue that has affected far less than 1% of the users, so it cannot be an issue that affects all of the users. Lol, but that ain't going to stop some people from continuing to look for issues that affect all of the users. I suspect there will be a few more case mods.

Hallmark won't make a comment without exp basis.

120ccpm Posted at 5-1 09:20
I hope the post above by Zbip57 convinced you that's not the case. At least, not in principle, that's not how quadricopters move forward. As I said above, practically things could be different for a variety of reasons, but it's not something you can guess just by looking at the drone, you would need complex modeling or wind tunnel tests, to study those effects.

OK, here's how I understand how rotors are working when flying  forward or Backward (see Image below)

Remember, I'm not trying to contradict your explanations, I'm just trying to understand and, can be useful to others.

Respectfully
Thanks for your help !

JGFly Posted at 5-1 11:04
OK, here's how I understand how rotors are working when flying  forward or Backward (see Image below)

Remember, I'm not trying to contradict your explanations, I'm just trying to understand and, can be useful to others.

No, that is incorrect. There are a couple of posts earlier with proper diagrams that show that both front and back are at the same RPM during forward flight. Unless that is what you meant that both front and back are at the same RPM during forward flight. If they are not at the same RPM then there will be a net torque and the drone will flip.

I'm out at the moment but when I get home I'm going to flatten my original Rear props and recreate what was tested from that Mavic pilots thread.

It's been found how to recreate the uncommanded descents, I'll try this on my original props and report back the findings.

Deucalion Posted at 5-1 10:55
I think he is talking about the FW warning, not just an RPM discrepancy, and none of the props tested here were triggering an FW warning, unless I missed something. I know mine weren't. HedgeTrimmer once said that some props might be exceptionally thin from the factory, which is plausible. In fact, anything that might only affect less than 1% of the users is plausible, and anything that would affect all of the users is implausible. We are dealing with an issue that has affected far less than 1% of the users, so it cannot be an issue that affects all of the users. Lol, but that ain't going to stop some people from continuing to look for issues that affect all of the users. I suspect there will be a few more case mods.

Again I’m talking about all tests done including GJ and there seems to be some confusion I’m not saying some props are bad they could well be, I’m saying that props were not the single cause of involuntary descents and it was clear to me that after last update that Mavic mini was a much improved craft and while I don’t expect dji to come out and tell us all what the cause was I’m certain they have done more than just try to show up a defective prop, if prop was the cause on its own we almost certainly would have seen a warning that read LAND IMMEDIATELY, not return home land and change prop, that warning is just telling you your prop is not working to its optimum and would advise changing .

fans1cafe718 Posted at 5-1 11:04
Hallmark won't make a comment without exp basis.

...and your hypothesis?

Well, I gave my opinion. The reason for an issue that less than 1% face can't be something that would affect everyone. I have a list...

1. Factory defects
2. User baked his props in an oven.
3. User put his drone in a case stupidly

Those satisfy the condition of only affecting a very few. I am not saying which if any is the actual reason. But if I were to pick, it would be 1. The only way to know is to take a random sample of props from the factory and test them.

hallmark007 Posted at 5-1 10:46
You completely missed my point, all tests were done stating props were bad and many users just bypassed replacing props and most received no warnings. If your advice is that props are bad and causing all involuntary descents, remember all tests showed “ bad props”  But all tests equally showed no drops in altitude and no involuntary descents, and if you take into consideration those who updated through assistant so unlikely to get warning to change props , that we would have seen at least one person reporting drops in altitude or worse drone lost from involuntary descent.

You must remember that if we look at the tests and take what we have seen literally, then 100% of drones tested showed discrepancies, not one passed all had some problems, so that would or should translate into all Mavic mini having prop discrepancies, so chances are pretty good if props ONLY are causing craft to descend, then we should see many many more very very soon dropping from the sky or land going backwards.

You seem to reason in binary terms, where a prop is either "good" or "bad". While we all use those terms for simplicity, I think it's pretty clear by now that there's all shades of gray in between. The Motor Error warning is just a fixed threshold (likely based on averages over a given window), and you might have a prop that is right at the limit of triggering it, so on one flight you get the warning, on the next you don't. Temperature and air density might be external factors causing the alert to appear intermittently.
A prop that is bad enough to trigger the Motor Error warning, might not be bad enough to trigger an uncommanded descent. The warning is DJI telling you "careful, this prop is losing pitch and causing high RPMs, you better off replacing it before it causes bigger problems". That's why they don't force you to land right away. Up to you if you want to ignore it. I personally won't.

Deucalion Posted at 5-1 11:12
No, that is incorrect. There are a couple of posts earlier with proper diagrams that show that both front and back are at the same RPM during forward flight. Unless that is what you meant that both front and back are at the same RPM during forward flight. If they are not at the same RPM then there will be a net torque and the drone will flip.

Hey guys, I promise you, I will not reply again. This is my last one.

@Deucalion Again with respect,

So, you wrote '' No, that is incorrect. There are a couple of posts earlier.....''

Precisely, I can't figure out how it can be possible. In the image (point 2-B) I suppose that Front rotors are not all the way increasing the RPM. Those must adjust the rotational speed in order to maintain a correct altitude without decreasing the forward speed.
Cheers!

Deucalion Posted at 5-1 10:55
I think he is talking about the FW warning, not just an RPM discrepancy, and none of the props tested here were triggering an FW warning, unless I missed something. I know mine weren't. HedgeTrimmer once said that some props might be exceptionally thin from the factory, which is plausible. In fact, anything that might only affect less than 1% of the users is plausible, and anything that would affect all of the users is implausible. We are dealing with an issue that has affected far less than 1% of the users, so it cannot be an issue that affects all of the users. Lol, but that ain't going to stop some people from continuing to look for issues that affect all of the users. I suspect there will be a few more case mods.

In all my time flying dji drones I have never known or heard anything like a bad batch of props and I’m certain if dji were putting out bad props it would have been noticed, and dealt with, some people say here that dji will not admit mistakes, I think for something as serious as props they would. Over the years I’ve seen recall for some P3 batteries for inspire and matrice batteries, I don’t think they would have hesitated to reissue props if they were the soul cause of this problem, I’ve seen them recall some osmos so Hedgetrimmer doesn’t even own a mini and it’s likely he’s never held a mini prop, as I said in another post when Mavic pro was released most users thought the pros would never get the craft in the air, and I’m certainly not saying props can’t get damaged, but they’re a lot sturdier than you might think to look at .

hallmark007 Posted at 5-1 11:15
Again I’m talking about all tests done including GJ and there seems to be some confusion I’m not saying some props are bad they could well be, I’m saying that props were not the single cause of involuntary descents and it was clear to me that after last update that Mavic mini was a much improved craft and while I don’t expect dji to come out and tell us all what the cause was I’m certain they have done more than just try to show up a defective prop, if prop was the cause on its own we almost certainly would have seen a warning that read LAND IMMEDIATELY, not return home land and change prop, that warning is just telling you your prop is not working to its optimum and would advise changing .

Ok, so that is a little plausible, that all of the descents were not caused by bad props. But I never saw a pattern of conditions so bad that they would ground the drone. There was wind involved in many, but you can't fly a Mavic Mini without a strong wind warning. I don't think it is allowed. What was involved with those drones and strong winds and not our drones and strong winds, was a slew of ESC warnings, as you said.

120ccpm Posted at 5-1 11:24
You seem to reason in binary terms, where a prop is either "good" or "bad". While we all use those terms for simplicity, I think it's pretty clear by now that there's all shades of gray in between. The Motor Error warning is just a fixed threshold (likely based on averages over a given window), and you might have a prop that is right at the limit of triggering it, so on one flight you get the warning, on the next you don't. Temperature and air density might be external factors causing the alert to appear intermittently.
A prop that is bad enough to trigger the Motor Error warning, might not be bad enough to trigger an uncommanded descent. The warning is DJI telling you "careful, this prop is losing pitch and causing high RPMs, you better off replacing it before it causes bigger problems". That's why they don't force you to land right away. Up to you if you want to ignore it. I personally won't.

Well so explain the guy who lost his drone first day out Renato I think his name is. Look we could go around in circles here again you think this is totally a prop issue I don’t , but I do know that many have bypassed changing particularly new props and we now know dji have asked those getting warning not to take it off but to physically check yes with your own eyes including trying to smooth out any imperfections.
That message is not saying anything about craft will fall out of the sky. There is a very good reason why mini is flying a whole lot better since last update and it has nothing to do with props .

Deucalion Posted at 5-1 11:30
Ok, so that is a little plausible, that all of the descents were not caused by bad props. But I never saw a pattern of conditions so bad that they would ground the drone. There was wind involved in many, but you can't fly a Mavic Mini without a strong wind warning. I don't think it is allowed. What was involved with those drones and strong winds and not our drones and strong winds, was a slew of ESC warnings, as you said.

Wind is the enemy of the mini, but the pilots responsibility, he chooses to fly he’s fully responsible, it’s almost impossible to sympathize with crashes that happen in unsuitable conditions, we know the parameters we’re all grown up.

I have much sympathy for someone who loses his drone in the wind and comes on and says he hadn’t a clue but it was his fault,

Well I’m not certain but as far as I remember moderators said this warning was false and would get sorted in next FW, there was drones lost mostly or exclusively to new users, and many thought that it would be a good idea to let drone Rth in S mode, it was a long discussion, and not one that needs anymore discussion .

Now for strong wind warning , warning just reads land immediately, but this problem was exaggerated because there were many completely green flyers when mini was released just like you will see when Air2 gets in the hands of new flyers, impatience and exuberance can cause many crashes.

hallmark007 Posted at 5-1 11:54
Wind is the enemy of the mini, but the pilots responsibility, he chooses to fly he’s fully responsible, it’s almost impossible to sympathize with crashes that happen in unsuitable conditions, we know the parameters we’re all grown up.

I have much sympathy for someone who loses his drone in the wind and comes on and says he hadn’t a clue but it was his fault,

Oh, I guess I seldom get (or have gotten) a Land Immediately version. I thought you meant strong winds.

In post #119, hallmark007 wrote, "one thing I have noticed with all the testing and discrepancies, we have not seen one craft involuntary descend, neither have we seen any other user reporting involuntary descent since last FW on this forum".

Let me fix that for you.

Here's a video below posted by mrkentdotcom.  At 8:20 in this video he shows a clip from an earlier flight (before the latest firmware version) when he experienced an involuntary descent into the ground while flying his Mini outdoors with the prop guards installed.  He received, and ignored, the Max Power Load warning.  His theory then was that the motors overheated.

In a previous video (with the most recent v1.005 firmware) he received the new Motor Speed warning.  He tries to fix that by lubricating the motor shafts with gasoline.

In this video below at 1:00, he admits the gasoline didn't help as the Motor Speed warning pops up again.  He ignores the warning and continues flying.  At 4:30 the Mini does an involuntary descent into the ground.  At 5:25 it does it again.  And at 5:50 again.  This is with the latest v1.005 firmware.


At 7:15 he says he tried re-installing the firmware but that didn't fix the problem.  Replacing the rear props, as instructed, did fix the issue.  He also seems to believe that the motors positioned highest (i.e rear motors when the Mini is pitched forward) must therfor be doing more work than the front motors.  I still disagree with that.


Here's the video:

In post #120, Deucalion wrote, "Well, at least we know that propellor degradation has nothing to do with  the issue of descents. Almost everyone has been using the original  props since the drone came out in December. That is a plus.".

Wait, what, huh?  How do we know that?

Previously it was Max Power warnings, now it's Motor Speed warning with explicit instruction for propeller replacement.  In either case, it's a warning that you ignore at your own peril.

Will it still fly if you ignore the warning?  Maybe, maybe not.  The threshold of the warning has to be set at a level where it will do some good and still give you time to land safely.  That's the whole point of a warning.  There's no point in issuing a warning after the Mini has crashed.

Zbip57 Posted at 5-1 14:10
In post #120, Deucalion wrote, "Well, at least we know that propellor degradation has nothing to do with  the issue of descents. Almost everyone has been using the original  props since the drone came out in December. That is a plus.".

Wait, what, huh?  How do we know that?

I think you need to read djis response regarding prop warning, their reply was simple fly home land Check prop if damaged change both half’s , if not damaged then its fine.

Regarding the video above anyone who’s putting gasoline in his motors is not really to be taken seriously.

I think now like others you’re convinced that bad props and nothing else caused uncontrolled descent, but as we have seen in ALL tests that 100% showed bad props so either there is something wrong with the test or every drone has same damaged props, as I’ve said on numerous posts since last FW Mavic mini is flying much better more stable and that usually comes from optimizations. And if all tests on this thread plus 2/3 other threads show props are bad then something is either wrong with the test or something is wrong with all mini drones props, you can’t have your cake and eat it.
I will also like to know why no prop warning on front props ?

In post #134, hallmark007 wrote, "In all my time flying dji drones I have never known or heard anything like a bad batch of props".

The original Phantom (P1) shipped with cheap props that were notoriously out of balance.  The vibrations from these unbalanced props spinning at speed created an awful "jello" effect on GoPro video images.  Each prop had to be painstakingly re-balanced by hand to cure the vibration.  In my opinion, that counts as a bad batch of props.

There have  even been cases reported of props coming off in flight.  With each new generation of DJI drone, improvements have been made in propellor design and mounting methods.  I fear that with the Mini, in trying to keep it under 250grams, there may be an issue in its propeller design.


My old Phantom even had one motor bell-housing that required re-balancing.

hallmark007 Posted at 5-1 11:36
Well so explain the guy who lost his drone first day out Renato I think his name is. Look we could go around in circles here again you think this is totally a prop issue I don’t , but I do know that many have bypassed changing particularly new props and we now know dji have asked those getting warning not to take it off but to physically check yes with your own eyes including trying to smooth out any imperfections.
That message is not saying anything about craft will fall out of the sky. There is a very good reason why mini is flying a whole lot better since last update and it has nothing to do with props .

I cannot find a single theory that explains everything we're seeing related to props, but I have confidence that this Motor Error warning works as expected, and this thread confirms it. We do not know why, but it's undeniable that some props perform worse than others. My MM has performed flawlessly, but if I get the warning I will replace props without hesitation. If you think it's BS, don't. We don't have to agree.

Zbip57 Posted at 5-1 14:10
In post #120, Deucalion wrote, "Well, at least we know that propellor degradation has nothing to do with  the issue of descents. Almost everyone has been using the original  props since the drone came out in December. That is a plus.".

Wait, what, huh?  How do we know that?

"In post #120, Deucalion wrote, "Well, at least we know that propellor degradation has nothing to do with  the issue of descents. Almost everyone has been using the original  props since the drone came out in December. That is a plus.".

Wait, what, huh?  How do we know that?

We know that the props are not degrading over time and causing the descents. We know this because of how many drones have been flying since this drone came out and how few had the descents and/or errors. Like I said in the post. When 1% have an issue, you don't look at the other 99% for the cause. You look at the 1%.

I never said to ignore an FW warning. I have always said to replace the props if you get an FW warning. That is what the warning is for. However, we had quite a few users get erroneous errors because the FW did not update properly, and I tell users to check the update first with DJI Assistant and after that, if there is still a warning, replace the props.

I just don't want to see is a bunch of people doing RPM tests and seeing variances and throwing away good props. Just because there are variances doesn't mean the props are bad. It also doesn't mean that they are fated to deteriorate till you get a warning. That hasn't been happening. Some people with brand new drones get warnings. Some props are just bad right out of the box.

Users should fly their drones with the props that are on them, and if they get a warning from the FW to replace them, they should absolutely replace them.

Deucalion Posted at 5-1 15:03
"In post #120, Deucalion wrote, "Well, at least we know that propellor degradation has nothing to do with  the issue of descents. Almost everyone has been using the original  props since the drone came out in December. That is a plus.".

Wait, what, huh?  How do we know that?

And it is good news that we don't have to worry that our props will degrade and not last very long. Isn't it?

In post #141, hallmark007 wrote, "I think you need to read djis response regarding prop warning, their  reply was simple fly home land Check prop if damaged change both half’s ,  if not damaged then its fine."

Do you have a link to DJI's response?  Where can we see that?

"as we have seen in ALL tests that 100% showed bad props..."

Which tests are you referring to?  Do you mean the graphs showing that rear motors are spinning faster than front motors?

That alone does not prove that any of the props are necessarily bad.  And, as we have seen, there are varying opinions on whether or not it might even be considered normal  that rear props spin faster than front props.

"I think now like others you’re convinced that bad props and nothing else caused uncontrolled descent..."


The problems (and warnings) arise once a motor exceeds a certain threshold speed.  When exceeding whatever threshold DJI has set in this new firmware, a warning is triggered.  Higher motor speeds are being commanded by the flight controller when not enough lift is being generated by that propeller.  There is an ulitimate maximum motor speed that the Mini is incapable of sustaining or surpassing.   If the prop is still not generating enough lift and the controller tries to compensate by demanding even more motor speed than it can put out, that results in an uncontrolled descent.

The question is why are such high motor speeds happening?  Not everyone has experienced the warning.  I have.  But I have thankfully never (yet) experienced an uncontrolled descent.  I replaced the blades on the affected motor, as instructed, and have not received any further warnings.

120ccpm Posted at 5-1 14:57
I cannot find a single theory that explains everything we're seeing related to props, but I have confidence that this Motor Error warning works as expected, and this thread confirms it. We do not know why, but it's undeniable that some props perform worse than others. My MM has performed flawlessly, but if I get the warning I will replace props without hesitation. If you think it's BS, don't. We don't have to agree.

You keep going on about the warning and how reliable you seem to think it is, now nobody here has argued that warning can detect a bad prop, but that doesn’t mean that every time it goes off you have a bad prop, for instance someone remove their new prop then replaced the new prop and no more warning, so that proves it can be wrong and this is backed up by djis reply telling user to first check prop for damage and I’m almost certain they didn’t mean X-ray the prop, and if prop is ok then it’s ok.

So nobody has said it’s BS and everybody knows that if warning reports a bad prop then you change it.
Like I said all tests done showed that all those who performed test had shown to have bad props, and yet not all of these showed warnings so if these tests are supposed to be correct then we should see many more drop outs or uncontrolled descending unless tests are BS or tests are correct and something else is keeping craft in the Air, but it seems that because dji have set up a warning that yourself and others automatically believe without proof that this caused the uncontrolled descents.

So if it suits you to think that I or anybody else here is recommending not to change bad props then think that way, but it shows you are being selective in what you’re reading.

I’ll say it for the last time, the warning can show you have a bad prop and it should be changed, the warning can also be proven to be inaccurate as many have shown.

Zbip57 Posted at 5-1 14:42
In post #134, hallmark007 wrote, "In all my time flying dji drones I have never known or heard anything like a bad batch of props".

The original Phantom (P1) shipped with cheap props that were notoriously out of balance.  The vibrations from these unbalanced props spinning at speed created an awful "jello" effect on GoPro video images.  Each prop had to be painstakingly re-balanced by hand to cure the vibration.  In my opinion, that counts as a bad batch of props.

It wasn’t a bad batch of props and no props were replaced , and P2 And P3 had similar problems but again it wasn’t only props, it seems you like to throw stones but don’t seem to answer many questions. I’m starting to feel like you’re here to troll.
If there was an issue with prop design why would dji do nothing about it, we've seen lots of other stuff recalled including batteries on inspire and matrice and P3 , so I expect you expect to see many more mini fall to the ground.

You again claim, "this is backed up by djis reply telling user to first check prop for damage".

And I again ask, where can we see for ourselves this reply from DJI?

Zbip57 Posted at 5-1 15:45
You again claim, "this is backed up by djis reply telling user to first check prop for damage".

And I again ask, where can we see for ourselves this reply from DJI?

Who appointed you head of the Stasi.

I look forward to your apology.

https://forum.dji.com/forum.php? ... 349&pid=2141568

Well I did it, I provoked and uncommanded descent on 1.05 and have it captured on video. I never got a motor speed warning, but I did get max power load reached and not enough force errors. I need some time to go over all of the logs from everything I tested tonight and go over the descent information, after I'll post back with all the graphs and video so we can go over tonight's tests.

ABeardedItalian Posted at 5-1 16:24
Well I did it, I provoked and uncommanded descent on 1.05 and have it captured on video. I never got a motor speed warning, but I did get max power load reached and not enough force errors. I need some time to go over all of the logs from everything I tested tonight and go over the descent information, after I'll post back with all the graphs and video so we can go over tonight's tests.

Let me guess.  You did it with Sports Mode or high wind speeds where the rear motor RPM's are maxed out.  Looking forward to your data.

Zbip57 Posted at 5-1 15:12
In post #141, hallmark007 wrote, "I think you need to read djis response regarding prop warning, their  reply was simple fly home land Check prop if damaged change both half’s ,  if not damaged then its fine."

Do you have a link to DJI's response?  Where can we see that?

Well you were very quick on the draw, cat got your tongue now.

You got the dji reply.

Regarding the graphs these were as a direct result of someone else on another thread proclaiming that graph showed bad props so they needed changing, it as indeed my point to try to point out that the graphs show very little and indeed similar graphs could be shown on many drones.

With regards to the warnings , so some got the warning on brand new props, so in order to get rid of the warning they removed prop and then reinstalled it and warning went away and no more warnings on flights so my point was simple warning is not always correct and now with dji asking to Rth and first check props for damage or any deformities shows it’s indeed correct to do due diligence .

You have already figured out what’s causing uncontrolled descent and have decided it’s bad props, but it seems that the law of averages show it to be on the same motor all the time, if props are bad why only one prop ? I mean does this not seem a bit odd, I could understand motor because it’s permanent so yes many faulty motors left rear, I could also understand not enough power going to one single motor so need to optimize to correct this, but bad prop is causing this but how can other motors handle the bad props ?

I also find it a bit strange you have suffered this warning that the vast majority have not received and you have a warranty, I’m sure you would rather own one like the vast majority.

Again it’s my belief that optimizations were improved overall on the mini and it is this that will play a big part in less uncontrolled descents, there are to many variables about wrongly stored, bad batch caused by boiling the plastic to long , warning coming because prop has flattened but the new prop what about that.

I think myself some have seen drops from very low altitude if one motor was struggling you would not have seen this just straight down to land, the attitude of the craft would show some lilt if nothing else.

Very nice write up on this issue.

Vlas Posted at 5-1 16:59
Very nice write up on this issue.

Yes, I must admit ...

.... But I would like to see DJI publish an official warning about defective propellers and at the very least apologize for the problems incurred and reimburse all those who had to obtain other propellers.

Yes I know, it would be very surprising if this happened but .......

ABeardedItalian Posted at 5-1 16:24
Well I did it, I provoked and uncommanded descent on 1.05 and have it captured on video. I never got a motor speed warning, but I did get max power load reached and not enough force errors. I need some time to go over all of the logs from everything I tested tonight and go over the descent information, after I'll post back with all the graphs and video so we can go over tonight's tests.

Can you provide the .DAT?

hallmark007 Posted at 5-1 15:59
Who appointed you head of the Stasi.

I look forward to your apology.

If you're waiting for an apology, don't hold your breath.  You accuse me of being a troll and head of the Stasi, and you expect me to apologize to you?  

You kept posting your nonsense about, "that proves it [the motor speed warning] can be wrong and this is backed up by djis reply telling  user to first check prop for damage and [...] if prop is ok then it’s ok.".  I asked you twice where DJI might have posted this supposed reply, thinking maybe there has been an official notice posted somewhere on their website.

But, no, your link merely points to someone else's secondhand copy of some reply received from one of the front desk DJI Tech Support folks.  It contains nothing specifically telling you that the abnormal motor speed warning may be wrong.  It says, "It is recommended that you replace the entire pair of propellers on the corresponding motor firstly."

It says check for any obviously visible damage and, "If there is a slight propellers deformation caused by improper storage, it is recommended that you smooth the corresponding propellers before  attempting." Presumably that means try repairing the prop yourself before attempting further flight.

Nowhere does it say to simply dismiss the warning and continue flying as though nothing is wrong. Nowhere in that message does it say the motor speed warning was an error.  Everything in that message points to a suspected propeller defect.

That said, I will not be wasting any more time entertaining your warped fantasies.  Good bye.  I look forward instead to seeing what new information ABeardedItalian has to present.  It is refreshing to read his posts filled with actual data and facts.

ABeardedItalian Posted at 5-1 16:24
Well I did it, I provoked and uncommanded descent on 1.05 and have it captured on video. I never got a motor speed warning, but I did get max power load reached and not enough force errors. I need some time to go over all of the logs from everything I tested tonight and go over the descent information, after I'll post back with all the graphs and video so we can go over tonight's tests.

Very interesting...hope to see it soon. Thx

hallmark007 Posted at 4-30 09:13
I just have a feeling you will see similar results with all dji drones, maybe jjb has logs from other craft.

There is much less speed discrepancy between front and rear motors my Mavic Pro. I happen to have logs which are used for power consumption checking but the only big speed discrepancy comes when aircraft has severe tilted due to acceleration or braking. see my second log for hover:



to say that you expect 50% speed discrepancy in hover between front and rear is like suggesting a 50% imbalance of weight distribution in the drone. Not to mention, if that is the design then surely the motors need to be designed to spin even faster.

Perhaps it helps that a little: I had ordered replacement propellers in the past. Two versions were delivered to me: production dates 12/2020 and 03/2020 (written on the label). The quietest and most stable are the ones with production date 03/2020 and I have no error messages with these after the update. It may be that the propellers have been modified in the meantime.