well , had my first experience with what i had only read about.......the dreaded " toilet bowling".   it happened to me in my confined takeoff and landing spot.   decided to give course lock a try, and it went well.  brought the bird back when the battery was getting low to hover and finish the battery to 35%.   well, things got interesting at that point, 10 feet up in the drive way, 3 cars, the house and a shed surrounded by trees.  the circling started.........sure glad i spent some time flying atti.......i landed the bird unscathed........but my confidence in it suffered !    i did playback the flight in the app, and saw a couple of sattelite positioning off errors, and compass errors during the episode but didnt see them at the time as i was focused on not crashing.    i did manage a textbook landing tho !

Holy crap is there a solar flare or something this week? I had a very sudden "disconnected from aircraft" situation today and few of my other friends had issues too In the last week or so

JakeFrye805 Posted at 2017-7-27 14:52
Holy crap is there a solar flare or something this week? I had a very sudden "disconnected from aircraft" situation today and few of my other friends had issues too In the last week or so

wish i knew what caused my " omg" couple of minutes of flight !   it was controlled panic trying to avoid crashing into things.   bought the bird back in january 2017, and it was a joy to fly up to that point.
i did fly again the last night , exact same take off point in the yard........perfect fight, the bird was rock solid.  

timnwcove Posted at 2017-7-27 15:21
wish i knew what caused my " omg" couple of minutes of flight !   it was controlled panic trying to avoid crashing into things.   bought the bird back in january 2017, and it was a joy to fly up to that point.
i did fly again the last night , exact same take off point in the yard........perfect fight, the bird was rock solid.

Aloha tim,

     Your problem is simple.  You were surrounded by massive amounts of metal in the landing area (cars and rebar in the concrete).  Your compass went bonkers.  Good you had ATTI as a back-up.  Now you know why you spent all those hours practicing!

     You need to find a different landing zone.  BTW, "Toilet Bowling" refers to Vortex Ring State (VRS).  Any Phantom P2 v.3 and above no longer experiences VRS because the motors have been angled and the descent speeds computer controlled to remove the threat.

     Hope this helps!

Aloha and Drone On!

Toilet Bowl effect occurs with many different models in fact .... Helicopters, Multi Rotors of all sorts ... and has never been eliminated from any ...

Once the model starts - its often the PILOT reacting that exacerbates it and it gets into a fusion of reactions ... the Flight Controller / Gyro vs the Pilot.
Been flying Heli's and MR's for years ...

Nigel

Good to hear that you had flown with ATTI mode as a skill back up. Your GPS interfered for some reason or the GPS arrow was not pointing straight forward if you got Toilet Bowl Effect.
Please check the environment and the compass module value. Calibrate the compass when you trying to take off and fly with caution.

Cetacean Posted at 2017-7-28 01:10
Aloha tim,

     Your problem is simple.  You were surrounded by massive amounts of metal in the landing area (cars and rebar in the concrete).  Your compass went bonkers.  Good you had ATTI as a back-up.  Now you know why you spent all those hours practicing!

Umm ... confusing two different issues there.
VRS is not related ... VRS is what could happen with a P2 where it could fall in its own wake turbulence - fall downwards with catastrophic consequences.
VRS is not something to worry about with the P3 and P4 series.
Toilet bowl effect is a tendency to do a slow horizontal spiral rather than hold position.  It's compass related and can be caused by a bad compass calibration or bringing a Phantom down close to a large magnetic influence - try flying 3 feet above a steel roof to see it.

Metal shed, cars, reinforced concrete, all these things you mentioned can screw with a compass.

Cetacean Posted at 2017-7-28 01:10
Aloha tim,

     Your problem is simple.  You were surrounded by massive amounts of metal in the landing area (cars and rebar in the concrete).  Your compass went bonkers.  Good you had ATTI as a back-up.  Now you know why you spent all those hours practicing!

no rebar, no tin roofs, only the same vehicles as usual.   (  i may have hovered to close to a vehicle........but the problem  persisted even when  the bird was 10-15 feet away from the cars)

DJI Thor Posted at 2017-7-28 02:19
Good to hear that you had flown with ATTI mode as a skill back up. Your GPS interfered for some reason or the GPS arrow was not pointing straight forward if you got Toilet Bowl Effect.
Please check the environment and the compass module value. Calibrate the compass when you trying to take off and fly with caution.

compass module value ?    i havent calibrated the compass since the upgrade before the last one !

Cetacean Posted at 2017-7-28 01:10
Aloha tim,

     Your problem is simple.  You were surrounded by massive amounts of metal in the landing area (cars and rebar in the concrete).  Your compass went bonkers.  Good you had ATTI as a back-up.  Now you know why you spent all those hours practicing!

Toilet bowl != VRS

Funny ... sorry ...

It is a well known matter with all Rotor based flying machines .... especially when gyros are involved ..

The Pilot gets into a situation where the model starts oscillating and creating a circular motion ... with Multi Rotors and the fitting of Flight Controllers - they can actually make it worse.

It can happen with or without Compass interference.
Ask any Model Helicopter or Multi Rotor pilot ...

Nigel

Labroides Posted at 2017-7-28 06:28
Umm ... confusing two different issues there.
VRS is not related ... VRS is what could happen with a P2 where it could fall in its own wake turbulence - fall downwards with catastrophic consequences.
VRS is not something to worry about with the P3 and P4 series.

Aloha Labroides,

     Mahalo for the clarification.  In that case, Tim definitely was toilet bowling!  Never had a toilet bowling myself. Interesting.

Aloha and Drone On!

microlinux Posted at 2017-7-28 08:35
Toilet bowl != VRS

Aloha micro,

     See Labroides correction in Post #7 and my concession on the issue in Post #14.

Aloha and Drone On!

quadpilot Posted at 2017-7-28 08:30
there may lie you problem and the answer ...always do a calibration after an update software
may also be worth doing an imu calibration at the same time

Aloha QP,

     As a sort of shortcut regarding your suggestion, one should at least check the sensor calibration page to see if a calibration is recommended.  Hope this helps!

Aloha and Drone On!

JakeFrye805 Posted at 2017-7-27 14:52
Holy crap is there a solar flare or something this week? I had a very sudden "disconnected from aircraft" situation today and few of my other friends had issues too In the last week or so

My Drone Disconnected today as well! luckily it started hovering and restarted, but it made my heart stop for a sec as well!

timnwcove Posted at 2017-7-28 08:17
no rebar, no tin roofs, only the same vehicles as usual.   (  i may have hovered to close to a vehicle........but the problem  persisted even when  the bird was 10-15 feet away from the cars)

Aloha tim,

     Please see Labroides' correction in Post #7.  What you are describing in Post # 9 is all it takes to compromise your compass.  You really need to find a different launch spot with no interference.  Your compass will remain compromised and cause toilet bowling until you calibrate it properly.

     Hope this helps!

Aloha and drone On!

Cetacean Posted at 2017-7-28 12:06
Aloha tim,

     Please see Labroides' correction in Post #7.  What you are describing in Post # 9 is all it takes to compromise your compass.  You really need to find a different launch spot with no interference.  Your compass will remain compromised and cause toilet bowling until you calibrate it properly.

my launch point has been the same for six months......a one foot square board on my lawn.   no issues ever until the episode when it started circling/toilet bowling after bringing it in for a landing.  did the check imu thing and it says its ok, will check the compass mod value tho.   charged both batteries with hopes of some low and slow flying tonight, but wind and fog has me grounded.   

timnwcove Posted at 2017-7-28 15:04
my launch point has been the same for six months......a one foot square board on my lawn.   no issues ever until the episode when it started circling/toilet bowling after bringing it in for a landing.  did the check imu thing and it says its ok, will check the compass mod value tho.   charged both batteries with hopes of some low and slow flying tonight, but wind and fog has me grounded.

As is the case with most unusual flight incidents, the best way to work out what was really happening is to look at actual flight data.
If you want to get to the bottom of this, go to http://www.phantomhelp.com/LogViewer/Upload/
Follow the instructions to upload your flight record.
Come back and post a link to the report it provides.

timnwcove Posted at 2017-7-28 08:19
compass module value ?    i havent calibrated the compass since the upgrade before the last one !

I calibrate mine before every flight! Guess I'm overly cautious with my super expensive toy  hahaha

timnwcove Posted at 2017-7-28 08:19
compass module value ?    i havent calibrated the compass since the upgrade before the last one !

It's on the Main Controller Settings----Advance Settings----Sensor----Compass. We recommend always calibrating the compass when changing another place to fly.

bricooper Posted at 2017-7-30 18:37
I calibrate mine before every flight! Guess I'm overly cautious with my super expensive toy  hahaha

Sad, as doing that is more likely to cause you problems than not calibrating. Calibrating before every flight is unnecessary and potentially dangerous.

DJI Thor Posted at 2017-7-30 18:49
It's on the Main Controller Settings----Advance Settings----Sensor----Compass. We recommend always calibrating the compass when changing another place to fly.

Really DJI Thor?
You ought to read the manual sometime because it disagrees with you.

Sorry to say this but it appears that at odd times - DJI persons on this forum are not updated by DJI .....

Nigel

Compass calibration is only necessary :

After major works to machine
Update of FW
Significant distance between flying locations - in 00's of miles !

It is far better once a good calibration is made - to leave it alone. Start playing with it too often and you run risk of a bad calibration.

Nigel

solentlife Posted at 2017-7-30 23:06
Compass calibration is only necessary :

After major works to machine

Where did you get the idea that you need to re-calibrate after a firmware update?
Even DJI have never officially recommended that.
Or if you travel some magic number of miles?
That's another one not mentioned in the manual.

L - you surprise me now ....

Given that FW updates are affecting the whole control and electronics of the gear - making sure calibrations are good is in my view valid and good practice.
There are many posts by others advising calibration after FW ...
IMU calibration  fact includes the interaction of compass to IMU .... see last line on IMU calibration page ....

Second - I have explained many times about compass errors .... Variation, Deviation and Anomalies.

The main reason for calibrating in a different location is due to Variation - the difference of magnetic north to true north on earths surface - this means that change of this error occurs only after significant distance ....
Deviation is due to fixed influences around the compass on the model itself - these do not change.
Anomalies are the local errors due to pipes / cables / iron ore deposits etc. etc. that may be at location. It is bad practice to correct for these as once AC rises away from the influence -you will then suffer comoass error. Better to move location to avoid.

My original profession was as a Professional Navigator .... Compass knowledge - magnetic, fluxgate and gyro were required subjects.

DJI manual is vague on the location part but does in fact say - calibrate when change location .... it does not say every flight - which so many misread.
The manuals unfortunately have a number of errors that DJI have not corrected, even though DJI have agreed changes. A not unusual matter for many manufacturers where manuals do not keep up with development.

Nigel

solentlife Posted at 2017-7-30 23:47
L - you surprise me now ....

Given that FW updates are affecting the whole control and electronics of the gear - making sure calibrations are good is in my view valid and good practice.

I'll challenge you on both.
There might be many posts by many people suggesting recalibrating after an update - but it's just superstition with absolutely no basis.
I've been flying these things for three years now and never recalibrated following a firmware update - and guess what?
Just like a Phantom compass doesn't lose it's calibration, a firmware update doesn't affect it at all.

So when you were a navigator, did you have to make adjustments or corrections to your compass depending on where it was?
Or did you have a compass like the one I did - one that always points to magnetic north no matter where it was.
I had to factor magnetic variation into my calculations but never "recalibrated" the compass.
Similarly you don't need to do it for the Phantom.
I've tried travelling 3600km east-west with no calibration and no issues.
I've been flying a P4pro since December and never calibrated it at all.
Opened the box from China, flew it and have kept flying it.

Check out an up-to-date DJI manual (not for the standard (they haven't updated that one yet) and see when DJI recommend recalibrating.

The main reason for calibrating the compass is so that the compass understands what magnetic effects are due to the earth and what is part of the Phantom.
It's the digital equivalent to having a licensed compass adjuster correcting your ship's compass so that it isn't affected by all the things around it.
That's why you do have to do it after modifications.

L .... suggest you re-read what you just typed .....

You say in second paragraph ... you don't correct (actually you ask me if I did ... but you are saying not)

Last paragraph then goes on to basically agree with my statement about Variation etc.

Make your mind up !!

As a Professional Navigator for over 17 years, and trained to 'swing / correct' compasses ... then I stand by my words.

........... soft iron balls !! ..................
OK for those who wish to know ...

When you rotate the model in its various planes of axis - the MAGNETIC flux alters as it rotates. Not only that but the resulting DEVIATION error of the model itself alters ... Its to do with the interaction of the magnetic forces ... a bit like waves on the sea when you get two or more meeting at angles ... alter those angles and the result alters. You have the magnetics of the model and the magnetics of location ... as you rotate - the result changes. The Electronics detects this and records to use as corrector. Alter one and the final result alters ... that is why you calibrate.

Variation is different across the earths surface as it represents the offset from True North of Magnetic North. Magnetic North lies in north Alaska and is actually moving slowly more westward. That is why Variation charts state year and rate of change against figures on the chart.

Anyway ... you move significant distance from  previous point ... the variation may have changed a few degrees, its not a linear line change - the variation lines have many curves along them  ... this in turn affects the FLUX as the model rotates in that location.

I readily admit that I do not re-calibrate compass even if I move right across country - a degree or so error for magnetic compass is nothing - but it is fact.

As to re-calibrating after FW updates - thats a personal choice - and as I said - because FW affects the overall control and action of the AC / gear - I prefer to know that all is good to go. I have a known spot in my grounds that I know is free of anomalies ... I do my IMU and Compass calibrations there.

When I compare my system to others, I find myself fairly middle road. One group calibrate literally every flight - seems to be a wide number ! and others literally once in their life - seems to be a few ! My view is that calibration is unnecessary 99% of the time but has in my mind valid times as a safeguard.

Nigel

solentlife Posted at 2017-7-31 01:33
L .... suggest you re-read what you just typed .....

You say in second paragraph ... you don't correct (actually you ask me if I did ... but you are saying not)

I've re-read and stick by what I said.
As a navigator, did you have to make adjustments or corrections to your compass depending on where (in the world) it was?
Or did you just leave the compass alone and add or subtract the local variation as appropriate?

Labroides Posted at 2017-7-31 02:01
I've re-read and stick by what I said.
As a navigator, did you have to make adjustments or corrections to your compass depending on where (in the world) it was?
Or did you just leave the compass alone and add or subtract the local variation as appropriate?

As you well know ...

Corrections are added / subtracted and no physical action on the compass itself - in NORMAL DAILY routine ... where nothing has happened to vessel.

But go to Dry Dock and have work done on the ship, or any work done on ship that can alter its flux state and its not unusual to have compass adjustor on board ... OR to do a full compass swing once sailed. Which equates to any work / update on a P3  etc. and then do a calibration.

Your question is invalid because its based on nothing done in any form to unit. If you read my replies - I say that 99% of the time I do not believe re-calibration is required. But I do believe that there are reasonable times when it is a good idea ... why can you not understand that and leave me to my differing view to yours ?

I don't say you should do as I say ... so please do me the return honour.

I leave it up to others to decide whether they believe me or not. I give my reasons based on training and many years use professionally.
Nigel

solentlife Posted at 2017-7-31 02:59
As you well know ...

Corrections are added / subtracted and no physical action on the compass itself - in NORMAL DAILY routine ... where nothing has happened to vessel.

It seems that you are agreeing with me now after telling me I was wrong.

So you didn't tweak, adjust, correct or calibrate your ship's compass because you sailed to a different geographic location.
Then why would you do it for a Phantom?
A properly calibrated or adjusted  compass points to magnetic north and doesn't need any meddling to do that wherever it is.

Labroides Posted at 2017-7-31 03:35
It seems that you are agreeing with me now after telling me I was wrong.

So you didn't tweak, adjust, correct or calibrate your ship's compass because you sailed to a different geographic location.

I really give up with you and your not reading what is clearly written.. I only agree with you when NOTHING is different ... repeat the word N O T H I N G.

You argue against calibrating after FW update ...

You argue against calibrating when moved significant distance

You then make statements that have little relevance ....

Let me try again ...

When you sail your ship ... cocunut .... whatever - YOU apply variation to the compass reading not the ship or anything else. YOU get that figure of the Variation Chart ... which is different wherever you are.

The P3 having been calibrated in ONE variation loc ation is then moved to another variation location with different error ... HOW will the P3 know that ? It will apply the SAME calibration as in the OTHER DIFFERENT variation error location.

It is NOT the compass that changes ... its the corrections to apply to it.

The Navigator applying Variation and Deviation is the same as the P3 applying its calibration ... that means if one alters - then you do not apply same as before ... you alter the corrections.

Sorry but I'm done with this - you are not understanding what is written and you seem intent on just arguing.

Nigel

if it makes any difference........my compass mod value , with the bird sitting on its normal launch pad/board is 1467.x- 1471.x.   

solentlife Posted at 2017-7-31 06:41
I really give up with you and your not reading what is clearly written.. I only agree with you when NOTHING is different ... repeat the word N O T H I N G.

You argue against calibrating after FW update ...

Oh - I forgot ...

A magnetic Compass does NOT point to Magnetic North. Only when freely suspended in a completely uninfluenced non-magnetic location.

A magnetic compass points subject magnetic pole + external influences.

If it did point to Magnetic North - then why would we have corrections to apply just to correct to Magnetic North - let alone to True North ...

Nigel

Compass Heading +/- Deviation = Magnetic North
Magnetic North +/- Variation = True North

Error East Compass Least
Error West Compass Best

QED

Nigel

solentlife Posted at 2017-7-31 06:45
Oh - I forgot ...

A magnetic Compass does NOT point to Magnetic North. Only when freely suspended in a completely uninfluenced non-magnetic location.

Last time I bother with this - you're a very confused boy Nigel.

A magnetic compass points subject magnetic pole + external influences.

Exactly ... which is what I've been saying.  
You correct out the external influences when you calibrate the compass.
Then it reads magnetic north and that's all it needs to do.

DJI have finally corrected their manuals (except for the Std) to tell you not to mess with the compass.
They don't recommend messing with the compass after a firmware update or travelling any distance at all, ever.
Thousands of users have tested this and don't mess with their compasses and suffer no compass issues.

But you're special and know all about it so go ahead and make up your own rules.

geez......guess my "toilet bowling" got flushed  due  to  chest puffing ! lol    plz wipe properly and get a grip fellas !   

Welp, I'm just glad to know I don't have to reset pre-flight everytime... now I need to figure out why the box pops up....  **sneaks away into a dark corner of the room**

Labroides Posted at 2017-7-31 14:02
Last time I bother with this - you're a very confused boy Nigel.

A magnetic compass points subject magnetic pole + external influences.

Not confused at all - you just cannot see or understand.

Bye bye ..