When looking at my MP4 flying at head height from the back, I noticed that the two props on the right are "in plane" with each other.
However, on the left side, the rear prop is off plane and "twisted" a little out of plane with the front prop.

I've only had it a week and it hasn't had any hard landings of any kind.

Has anyone else noticed something like this?
It does seem to fly well but it just looks weird to me.

This is by design, some say it is to help avoid Vortex Ring State.

That may be so but personally I think the lean is also used in controlling the yaw of the drone, since the motors lean the thrust from their propellers has horizontal components that create turning moments about the drones centre of mass.
The latter is in addition to any pure torque genrated by the motors 'twisting' the propeller blades through the air.

You will find 'motor lean' on probably all the DJI drones and certainly  with the Phantom 3adv/Pro, Mavic 2 Pro/zoom, Mavic Mini and Mini 2.

Sean-bumble-bee Posted at 2-3 07:38
This is by design, some say it is to help avoid Vortex Ring State. You will find motor lean on probably all the DJI drones.
That may be so but personally I think the lean is also used in controlling the yaw of the drone, since the motors lean the thrust from their propellers has horizontal components that create turning moments about the drones centre of mass.
The latter is in addition to any pure torque genrated by the motors 'twisting' the propeller blades through the air.

Well, thank you for that.
When I first saw that, knowing I've not even had a hard landing and certainly no crashes, I picked it up and looked at it closely.
I saw nothing out of sorts with the arms or pivots of either arm, and not a scuff in site. Still looks brand new (which it is being only a few days since I got it and have only flown it half a dozen times).

I came to it being only one of two conclusions; that it was a design feature to stabilize or improve flight performance, or that it was a manufacturing defect.
I didn't think it was a defect because everything was so "tight" with no visible clues as to why it was like that.

I invite others with the MP4 to chime in and verify what I see with mine.
Look at yours flying at head height from the back and see how the left rear prop arc seems to be out of sync with the left front prop arc while the two prop arcs on the right side are perfectly aligned.

Hi there. Thank you for reaching out and we do apologize for the trouble. Please upload a short video showing the issue so we can check it further. We will surely provide feedback after we review the issue of yours. We appreciate your cooperation.

You mentioned the front props and one of the rear props.
What about the right rear prop?
If the Mini 4 is like most DJI folding drones, the front props are set lower than the rear props.

If you are concerned that the motors aren't vertical, that's by design.
Since 2015 the motors of DJI drones have been offset a few degrees off vertical.

If your drone hovers and flies properly, that's confirmation that all is OK.

DJI Paladin Posted at 2-3 20:24
Hi there. Thank you for reaching out and we do apologize for the trouble. Please upload a short video showing the issue so we can check it further. We will surely provide feedback after we review the issue of yours. We appreciate your cooperation.

Ok, here we go. I hovered my MP4 at eye level and took a pic from the back.
Yes, I understand about how the props are all tilted a little, but the tilt laterally outboard should still (I think) be the same on each side respectively.
Looking at the picture I've added here, note how the two props on the right side are "in plane" while the two props on the left are clearly out of plane with each other. The rear prop has a distinctive downward tilt compared to the front prop, and you don't see that on the right side.
I hope this helps to clarify.

I think you would do better to place the drone AND camera on a table top.
In the above phtoto the entire left rear arm seems to be drooping but it is difficult to tell whether or not the drone is level. The lowest fence rail appears to be more or less horizontal but 'measuring' from that the left front arm is higher than the right front arm and the left rear battery bump is LOWER than the right rear battery bump.
See the attached, marked up, cropping from your photo.
THe thin black lines in the cropping were drawn from the relevant points on the drone to that rail then copied and pasted to the corresponding points on the right. The red line is a 'horizontal' drawn across your photo.
It is possible that there is a viewpoint, perspective ? error introduced in the photo.

Sean-bumble-bee Posted at 2-4 09:44
I think you would do better to place the drone AND camera on a table top.
In the above phtoto the entire left rear arm seems to be drooping but it is difficult to tell whether or not the drone is level. The lowest fence rail appears to be more or less horizontal but 'measuring' from that the left front arm is higher than the right front arm and the left rear battery bump is LOWER than the right rear battery bump.
See the attached, marked up, cropping from your photo.

Good suggestion, and I'll do that later today and post it tonight.

However in the mean time, I want to point out that I took this photo while the MP4 was hovering "in place" with little to no wind.
That means that the drone is supposed to be level while hovering in place.
If we can assume (I think we can) that the fence is perfectly level, is it possible that the drone is compensating for the drooping arm and having to assume a non-level position in order to stay in place?
You also asked if there might be a perspective issue, but I observe this off kilter anomaly at all times, not just in this photo which is only a snapshot of what I always see.

As I said, I'll post another photo of the MP4 sitting on a table later on.

Sean-bumble-bee Posted at 2-4 09:44
I think you would do better to place the drone AND camera on a table top.
In the above phtoto the entire left rear arm seems to be drooping but it is difficult to tell whether or not the drone is level. The lowest fence rail appears to be more or less horizontal but 'measuring' from that the left front arm is higher than the right front arm and the left rear battery bump is LOWER than the right rear battery bump.
See the attached, marked up, cropping from your photo.

Right

Left

Center

Let's try this.

There are 3 photos here. One is from a slightly left of center from the back, one is slightly from the right from the back, and one is centered from the back.
You mentioned a perspective issue and I do understand that.
So what I have done here is intentionally create perspective anomalies by shooting from three slightly different angles.
Still, even when you take into account those perspective differences, the relationship of the left rear prop to the left front prop still appears to be MORE of an angle difference between the two than on the right side in all 3 photos.
Or am I over-thinking this?

My concern is that if there actually is a difference as I describe, then the MP4 will compensate by driving more power to (various) motors in order to keep it flying in the orientation that the navigation electronics demand.
That would mean more demand on the battery than it should be and lesser flight times (which I admit would be hard to determine considering the changing conditions over each flight... I'm talking in a logical generality here).

So, what do you think?

Chizenbop Posted at 2-4 11:41
[view_image][view_image][view_image]Let's try this.

There are 3 photos here. One is from a slightly left of center from the back, one is slightly from the right from the back, and one is centered from the back.

However in the mean time, I want to point out that I took this photo while the MP4 was hovering "in place" with little to no wind.
That means that the drone is supposed to be level while hovering in place.
Your assumption here, is not necessarily true.
In flight, your drone is constantly correcting for small air currents and position holding.
It's rarely sitting at exactly 0.0° pitch and 0.0° roll

If you looked at the flight data for the time that this image was recorded, you'd find how level the drone actually was at the time.
Or am I over-thinking this?
YES
If your drone hovers and flies normally, you have nothing to be concerned about.

My concern is that if there actually is a difference as I describe, then the MP4 will compensate by driving more power to (various) motors in order to keep it flying in the orientation that the navigation electronics demand.
That would mean more demand on the battery than it should be and lesser flight times (which I admit would be hard to determine considering the changing conditions over each flight.
In normal flight and hovering, your drone is constantly making the kind of adjustments you describe.
That's what it does and it's normal.

To my eyes those look perfectly fine, they look to be mirror symetrical about an axis running from the front of the drone to the rear of the drone.
If you look at the inner blade tips they seem to be of almost of equal height, using a camera will probably distort the impression due to the speed of the exposure and the blades may not be perfectly straight.

With regards to your concerns about motor loads etc., controlling motor speed is the essence of how these drone maintain stablility, they continually change drone tilt and motor speeds to keep the drone stable and in postion, minor lopsided loading won't damage any thing.

If you remain concerned, ensure that you have the phone and or controller disconnected from the internet, so that it CAN NOT sync logs with DJI, then fly an indoor hover ( 2 or 3 minutes of hovering with NO joystick input ), in a well lit room that has a clearly defined pattern on the floor or a landing mat etc. on the floor ( so that the VPS system has a good target by which to hold postition ) and away from walls and draughts and not over things that can flap in the drone's down draught.
Land the drone and switch it off, then copy the contents of the MCDatFlightRecords folder, which will be found in the screen device ( controller or phone ), to your computer and ask DJI if they will have a look at the DAT for the hover flight.
I would guess that the DAT from the screen device contains motor speeds but I think these DAT's are encrypted so I doubt I would be able to check.

With a Mini 3 Pro these DAT's are NOT encrypted and do contain the mptot speeds but I do not have any from a draughtless hover, so looking at their motor speeds for this sort of thing is pointless.
You could check whether or not the Mini 4 Pro screen device DATs are encryoted by trying to process one of those DAT's with CsvView or DatCon. https://datfile.net/CsvView/downloads.html
There are a set of DAT's on the drone but they are HUGE and almost certainly encrypted.

Lots of  good info there. I'll try hovering it indoors and follow your suggestion.
Thanks

Chizenbop Posted at 2-4 07:53
Ok, here we go. I hovered my MP4 at eye level and took a pic from the back.
Yes, I understand about how the props are all tilted a little, but the tilt laterally outboard should still (I think) be the same on each side respectively.
Looking at the picture I've added here, note how the two props on the right side are "in plane" while the two props on the left are clearly out of plane with each other. The rear prop has a distinctive downward tilt compared to the front prop, and you don't see that on the right side.

Thank you for your response, Chizenbop. Please confirm if you experienced any issues when flying and hovering your unit? Does the unit unstable when flying? We will forward this to the relevant team for further clarification. We will surely provide you updates soon.

Hi there. Thank you for patiently waiting. Upon checking, it was found that this is under normal range. It is originally designed to maintain the aircraft stability, feel free to use the unit. Should you have other inquiries, feel free to contact us. Have a good one!