Height stability over water

[Fearless Flight]

Main Rule for me: NEVER have downward vision sensors on being low over water.

That was always the rule with the MP1 so I'm glad to know it's a good idea to do the same on the MP2

 

[SteveCA]

I fly 90% of my flights over water. VPS is problematic when flying over moving water. I always turn it off as it also interferes with hand catching. it can be turned off by clicking on the flight button, advanced, toggle vps to off.

If you use any intelligent flight modes or hyperlapse, it will require VPS to be on.

Also, I’ve learned not to trust the height info with my Mavic Pro as it was often wrong by as much as 60 feet. I haven’t tested the accuracy of the height info on the mp 2 yet.

 

[Elton Hammonds]

Many thanks Elton and appreciate the offer of help. They replied to me and will ship to Portugal; total price of around 120$. Its really tempting...

You're welcome. It's a unique product and I love supporting small businesses that come up with sort of thing.

I'm glad to hear they will ship to you. I know international mail can be crazy expensive. My wife and I send packages there a few times a year.

 

[wanderlust86]

Main Rule for me: NEVER have downward vision sensors on being low over water.

Hi Max,

Could you break it down for me: why exactly should you turn your downward vision sensors off being low over water, given the height is adjusted via the barometer (which, incidentally, could be the reason the Mavics get sucked down, since wave crests and troughs change the local air pressure in the space immediately above them)?

Thanks!

 

[ScubaBob]

M2P arrived Friday and had the chance to take it fopr a few test flights over the weekend. Today was hovering over a river about 5m above the surface and i noticed that the drone fluctuated its height often dropping down by around half a meter, was a little unerving given i was pretty low anyway. The weather was very calm and the river had little movement either. (I had all the obstacle avoidance turned on and not in beginner mode). Is this to be expected or are there any sesnors that should be turned off when flying over water?

Loving the drone! Stunning photos, quiet and flawless connectivity - a big step up from the air.

Appreciate any help.

I fly over the oceans regularly--generally launching from shore and going out 200-400 meters. The first thing I do is visually position my MP about 15 feet above the highest wave crest. I then look at my display to see what my drone is showing as its altitude. Since I launch at land and go out over the water my launch point is always higher than the ocean so to make sure I don't dip into the water I never send my drone lower than the altitude shown when 15 feet above the wave crest. Water plays strange tricks on the MP sensors and if you are not careful you will find your drone at the bottom sooner rather than later.

 

[Mike_Flys]

Living in Lake County FL, I have tons of time flying my Mavics (Pro, Air, 2 Pro) over water. For launching from my Kayak or low flying I use my float kit which has saved my Mavics 3 times in the past couple of years including my Mavic 2 Pro a couple weeks ago.

 

[MaxHam]

Hi Max,

Could you break it down for me: why exactly should you turn your downward vision sensors off being low over water, given the height is adjusted via the barometer (which, incidentally, could be the reason the Mavics get sucked down, since wave crests and troughs change the local air pressure in the space immediately above them)?

Thanks!

I can't explain you technically. I guess it's because water is constantly moving and reflecting light different ways.
It is just what I observed with my P4P and others have seen the same symptoms.
I can imagine the downward sensors override the barometer once they have 'visual contact'.
It feels like they can adjust height in centimeter range.

The manual also warns about water:

 

[tcope]

The manual also warns about water:
View attachment 49050

"Vision System". This is the camera on the bottom of the Mavic. This does not control altitude in anyway.

The reason people _think_ turning off downward facing system helps is because of old information. Ultrasonics used to control altitude under normal flight with the P3 and P2.

 

[tcope]

Could you break it down for me: why exactly should you turn your downward vision sensors off being low over water, given the height is adjusted via the barometer (which, incidentally, could be the reason the Mavics get sucked down, since wave crests and troughs change the local air pressure in the space immediately above them)?

It is not a "main rule"... or at least not unless you are talking about a Phantom 2 or Phantom 3 (which we are not as this is the Mavic forum). As I mentioned above... it is people using old information and still applying it.

 

[MaxHam]

"Vision System". This is the camera on the bottom of the Mavic. This does not control altitude in anyway.

The reason people _think_ turning off downward facing system helps is because of old information. Ultrasonics used to control altitude under normal flight with the P3 and P2.

The M2P has two downward sytems - vision and infrared.
Now I'm not sure which one controls what.

But one thing is for sure (and we had that discussion before):
That system holds altitude perfectly.
Try it inside your home with on/off and you know hat I mean.

 

[tcope]

The M2P has two downward ystems - vision and infrared.
Now I'm not sure which one controls what.

See the two big screens on the bottom?



Those are ultrasonics. I think you are confusing infrared and ultrasonics.

Ultrasonics _only_ control altitude when using Active Track and Terrain mode. Otherwise, they don't. The cameras also don't control altitude. So there is no need to turn the off in order to prevent altitude change.

 

[MaxHam]

See the two big screens on the bottom?

View attachment 49056

Those are ultrasonics. I think you are confusing infrared and ultrasonics.

Ultrasonics _only_ control altitude when using Active Track and Terrain mode. Otherwise, they don't. The cameras also don't control altitude. So there is no need to turn the off in order to prevent altitude change.

No idea which drone you are showing but this is not a M2P which this thread is about.

 

[carlb60]

Page 44 of Mavic Pro manual shows how to disable "Forward Vision System" which also seems to control downward vision system. I can tell you absolutely that something causes sudden descent when over water or any fairly smooth surface. Mine survived a bath in 5' of fresh water by drying in the sun. and crashed on my head when hovering over flat concrete. I have not tried to disable "Forward Vision", but will try it next time out because mine crashes everytime I hover below 15' over any flat surface. This is my fourth DJI drone and I have been flying for more than 5 years. This is the first one with the sudden crash syndrome. Don't give up on it if yours crashes in fresh water. Mine still works just fine - battery not, but everything else seems to work well. I think there is a conflict between GPS and Forward Vision System when hovering. All my crashes happened outside with at least 9 satellites.

 

[carlb60]

Oh, and yes I have the latest firmware - just updated it both drone and RC. I have downloaded all kinds of data, but cannot figure out what to do with it or how to interpret it. Book does not help and all the tutorials don't seem to work for me. Do I want to download "Black Box" or "Flight Logs" and whatta I do with them once downloaded?

 

[Vasek]

Spend now 10 days at sea flying 10-15m above the calm sea doing a photos and video of my friend fishing ship no issue at all plus twice 3km to next island at 100m height just fine. Switched all sensors off otherwise wont be able to catch M2P in hand on 15ft boat...

 

[carlb60]

Spend now 10 days at sea flying 10-15m above the calm sea doing a photos and video of my friend fishing ship no issue at all plus twice 3km to next island at 100m height just fine. Switched all sensors off otherwise wont be able to catch M2P in hand on 15ft boat...

Thanks Vasek - I'll try sensors off next time out

 

[Vasek]

Thanks Vasek - I'll try sensors off next time out

The sensors were on only when i did the satellite quickshot then i switched them off again

 

[rwest]

See the two big screens on the bottom?

View attachment 49056

Those are ultrasonics. I think you are confusing infrared and ultrasonics.

Ultrasonics _only_ control altitude when using Active Track and Terrain mode. Otherwise, they don't. The cameras also don't control altitude. So there is no need to turn the off in order to prevent altitude change.

You seem to be confusing the Mavic Pro (pictured) with the Mavic 2 Pro (which this thread is all about). The Mavic Pro does have an ultrasonic emitter & detector, the Mavic 2 Pro doesn't - and therefore is not confused in the same way as the original Mavic was.

 

[tcope]

No idea which drone you are showing but this is not a M2P which this thread is about.

I stand corrected, thank you.

I am not 100% sure how the infrared sensors react to altitude. I suspect that they operate the same way as the ultrasonics (just further). I'm pretty sure I have read that they only adjust altitude in Active Track mode.

 

[tcope]

You seem to be confusing the Mavic Pro (pictured) with the Mavic 2 Pro (which this thread is all about). The Mavic Pro does have an ultrasonic emitter & detector, the Mavic 2 Pro doesn't - and therefore is not confused in the same way as the original Mavic was.

I don't know that the Mavic Pro was ever confused. People just thought it was. The ultrsasonsics did nothing in normal flight. I'm not sure about the Mavic 2 but I _suspect_ it is the same way... the infrared only operate in Active Track in order to control altitude and not in normal flight mode.