Crazy Scary Excessive Wobble

[jkissing]

I was flying around some rivers in northern Canada. IRST Instance I was hovering about 20 feet above some rapids and it got wobble/scary so I upped the altitude and it smoothed out. 2nd Instance another less flowing not so swift river at about 15 feet the same really scary wobbling occurred, 45 degrees side to side. The wind did not seem present at all. So what is going on? Would N mode be better than tripod or is stuff going on that I can't see or sense in the air? To my surprise video was stable but it looked like craft might have lost control. My first post and Thanks

 

[bumper]

Not sure of the particulars of your flight, but it's true that fast moving water, and waterfalls in particular, can create significant turbulence and strong downdrafts in the air. Also, whenever there exists a downdraft (or updraft) there will be inrush air to fill the void (low pressure area) caused by the departing air.

 

[SkyeHigh]

Moving water can very easily confuse the downward facing sensors and unstablise the aircraft. And it’s not the only surface that can cause this. Flying low over a field of sugarbeet in sunny weather caused my M2P to do similar. The glossy leaves were moving in the wind and reflecting the sun. Climbing higher and stability returned to normal.

 

[rcourtney671]

I was flying around some rivers in northern Canada. IRST Instance I was hovering about 20 feet above some rapids and it got wobble/scary so I upped the altitude and it smoothed out. 2nd Instance another less flowing not so swift river at about 15 feet the same really scary wobbling occurred, 45 degrees side to side. The wind did not seem present at all. So what is going on? Would N mode be better than tripod or is stuff going on that I can't see or sense in the air? To my surprise video was stable but it looked like craft might have lost control. My first post and Thanks

My MA2 didn't get the wobbles you describe but while positioning for the second shot in this video I shot this past Sunday, I noticed the aircraft started to slowly descend on it's own. It kinda freaked me out because I was hovering only 8ft. to 10ft. above the water surface. I pulled up after getting the shot. Thank goodness I was watching the aircraft at the time and not the screen, otherwise I might not have noticed the slow descend while hovering.

 

[boblui]

Can you post the .TXT and .DAT flight log files in the phone for a more informed cause analysis ? The following instruction is extracted from Mavic Flight Log Retrieval and Analysis Guide :



3. LOG FILE RETRIEVAL

Mobile device DJI TXT logs

The log naming convention, based on the date and time of the start of the flight, is: DJIFlightRecord_YYYY_MM_DD_[hr-min-sec].txt.

Instructions to find and upload the files directly, with an option to make them public via a link, can be found on both @msinger's excellent PhantomHelp website or on AirData. Those both allow subsequent download of the original txt logs for third-party analysis.

Alternatively, to simply retrieve the txt logs from the mobile device:

With iOS devices running DJI GO 4 you need to access the app files via computer, either using iTunes or with a file system browser such as iExplorer. The TXT logs are in Apps » DJI GO 4 » FlightRecords. The same method can be used to access DJI Fly files in DJI Fly » FlightRecords, but with DJI Fly they are also accessible using the iOS Files app by selecting Browse » On My iPhone » DJI Fly » FlightRecords.

With Android devices the file system should mount when plugged into a Windows machine, or via various software options on a Mac. With DJI GO 4 the TXT logs are in DJI » dji.go.v4 » FlightRecord. With DJI Fly they are in DJI » dji.go.v5 » FlightRecord.

Under iOS the DJI Fly app files are actually accessible directly in the iOS "Files" app, but the DJI GO 4 app doesn't have that option.

If you want help analyzing the data then you can either retrieve the logs and post them here directly, or upload them to PhantomHelp or AirData and post the link back here.

AirData also has automatic log upload (sync) options directly from most of the common control apps.



Mobile device DAT files (DJI GO 4 & DJI Fly)

The DAT file naming convention, based on the date and time of the start of the file, is: YY-MM-DD-hr-min-sec_FLYXXX.DAT., where XXX is the flight recorder file index from the HOME_dataRecorderFileIndex field in the txt log.

These are retrieved by the same method as the TXT logs. Under both iOS and Android they are in a subfolder, MCDatFlightRecords, in the folder that contains the TXT logs. In some cases, for reasons not fully explained but possibly mobile-device hardware related, and most often under Android, DAT files are not created and that folder is empty. Uninstalling and reinstalling the app sometimes fixes that. One user also found that the process required manual deletion of the app folder (apparently not deleted automatically in the uninstall process) before reinstalling the app.

The DJI Fly app deletes the DAT files if and when it syncs flight records with the DJI servers, and so they are often missing from the MCDatFlightRecords folder. The iOS version of the DJI GO 4 app does the same since version 4.3.24. The Android version of DJI GO 4 does not delete the DAT files as of 4.3.32.