Flying over water with VPS...

Sn4pper · Oct 8, 2020

I’m planning a flight over a small section of water...

Should I turn off VPS Sensors? I’m thinking maybe not as it’s not exactly an open lake/seas?

I’ll be flying between 100-350ft.

Just to be on the safe side... ?

E90RAW · Oct 8, 2020

Sn4pper said:
I’m planning a flight over a small section of water...

Should I turn off VPS Sensors? I’m thinking maybe not as it’s not exactly an open lake/seas?

I’ll be flying between 100-350ft.

Just to be on the safe side... ?

View attachment 114671

You dont have to turn it off. I have made repeated flights over 2-3 miles of ocean at a height between 5 feet and 50 feet with it on or off never having an issue. The only issue with these drones is the height inaccuracy. Make sure you reset the height if you will be close to the water. Ex/ the drone may say your at 10 feet when in reality you are at 2 feet.....splash!!!

Otisangb · Oct 8, 2020

Sn4pper said:
I’m planning a flight over a small section of water...

Should I turn off VPS Sensors? I’m thinking maybe not as it’s not exactly an open lake/seas?

I’ll be flying between 100-350ft.

Just to be on the safe side... ?

View attachment 114671

At the height your talking about no problem, leave them on.

SkyeHigh · Oct 8, 2020

Sn4pper said:
I’m planning a flight over a small section of water...

Should I turn off VPS Sensors? I’m thinking maybe not as it’s not exactly an open lake/seas?

I’ll be flying between 100-350ft.

Just to be on the safe side... [emoji848]

View attachment 114671

I know that spot very well. Spent three happy years in Sprotbrough and many a day by the river, canal and the old quarry not too far away. And the Old Rectory, once home to the famous Ace RAF Pilot Sir Douglas Bader.

Coincidentally I’ll be driving over that very bridge tomorrow morning!!

A great spot for some photos.

Meta4 · Oct 8, 2020

Sn4pper said:
Should I turn off VPS Sensors? I’m thinking maybe not as it’s not exactly an open lake/seas?
I’ll be flying between 100-350ft.

Your VPS sensors have a max range of about 10 metres.
The definitely won't have any idea what's below them at 100 feet or more.

boblui · Oct 8, 2020

Turn off VPS when flying over water or the drone will go swimming is probably the biggest unsubstantiated believe spread in this community.

My advice is the opposite : leave them on unless you want the drone to go into the water. You can easily verify it by yourself. Start with the craft hovering about 2 meters above water surface and then apply a small amount of down throttle to make the craft descend.

With VPS off, the drone will go straight towards the water until the throttle stick is released or the drone gets wet.

With VPS on, the drone will automatically stop descending at 1 meter above the water surface. It will continue to go down only if you hold the throttle stick fully down for more than a second.

Sn4pper · Oct 9, 2020

Thanks for the responses Thumbswayup

boblui · Oct 9, 2020

Drone-Retriever said:
.... Light reflecting off the water will cause sensors to be confused as they see a mirror.
...the drone will initiate a command to land ....

The theory of "water confusing the sensor" has been mentioned many many times and yet no one has explained why such "sensor confusion" can cause the drone to "initiate a command to land"

One does not need to be a drone expert to see that the theory is wrong. If the reflection can "confuse" the bottom sensors in any ways, there can be only two outcomes : (1) The actual height above the water surface is less than what the sensor tells and (2) the opposite

In either case, the drone will not react at all. Just try to put your hand at different distances from the bottom of the craft when it is hovering, will it initiate landing by itself under any circumstance ? Of course not. It will only go up automatically if your hand gets too close. That's all. It will NEVER go down by itself. If it does, there must be some other reasons such as the throttle stick being pulled down.

Tweeter · Oct 9, 2020

Drone-Retriever said:
boblui
Suggest you get a very large mirror an place it on the ground. Have the sun high in the sky. Fly your drone over the mirror at about 4 feet and hover. Now with a friend lift the mirror toward the drone. That should answer your questions.
Hope this helps.

Please tell us what will happen as not all of us have a large mirror which would enable us to perform this experiment. Also, what happens if instead of raising the mirror you pull down on the left stick both momentarily and also pull down and hold. Thank you.

Squidinc · Oct 10, 2020

I flew twice this week without disabling sensors over water (surf & ocean) without any issues. Hovering as well whilst I fiddled with video and still formats, again without issue, and not far off the surface. See attached.

Kaydet · Oct 10, 2020

I have flown multiple times over water up to well over 10K feet without any loss of signal or erratic behavior. Longest flight was 33k feet over water and swamp. All at 20 to 30 feet AGL. The M2P will fly over water up to and beyond VLOS limits. Go find a flight crew member (or two) to serve as a visual observers and test its limits. It’s an impressive piece of gear and missions over water where there is nothing to attenuate the control signal will illustrate its capabilities.

DanMan32 · Oct 11, 2020

Two potential issues:
Misreading of altitude if IR penetrates through the water and hits bottom, where it considers land below surface as ground when your concern is water surface. Think of the movie Die Hard 2 where ILS was recalibrated to appear 100ft higher than actual, and what happened to one of the planes because of it.

Water movement or waves are tracked as if stationary, where the AC tracks the wave and follows it. Think of a treadmill or people mover. It will probably self correct with GPS, but since GPS resolution is less than VPS, it may be a bit erratic.

DJI does indeed instruct caution when flying over water at low altitudes because of how VPS might misinterpret the water.