Flow low above water surface

[TimVL]

For an assignment from my client, I want to fly low over the water with a DJI mini 2 or DJI mavic pro. And by low I mean about 50 cm above the water.
Does anybody have experience with this? And is the drone still stable? I read on the DJI website that you can turn off the Vision Positioning Sensor (VPS).

Hopefully someone can tell me more about this. Because it is an important point for my client. But I want to keep my drones dry

Regards Tim

 

[Anthony Ivory]

For an assignment from my client, I want to fly low over the water with a DJI mini 2 or DJI mavic pro. And by low I mean about 50 cm above the water.
Does anybody have experience with this? And is the drone still stable? I read on the DJI website that you can turn off the Vision Positioning Sensor (VPS).

Hopefully someone can tell me more about this. Because it is an important point for my client. But I want to keep my drones dry

Regards Tim

Let me know how long it takes you to get a new drone
You can use your zoom to simulate flying low.
There are 500+ stories of how unpredictable it is flying low over water are you trying for 501?
Maybe an AVATA would be a better choice

 

[FLDave]

You won't be able to rely on any accurate above-surface measurements from the drone. The water surface must be free of wave, undulations, and water spray.
This means must maintain perfect visual control of the drone and be able to accurately visually determine the height above water at all times. You must be able to determine visually if the drone descends to less than 50 cm above the water surface at any time. You must also be able accurately and quickly make manual height adjustment.
Attempting the maneuvers based on automated systems is extremely risky and likely end in failure.
There are many reports of failure for flights low over water; just search the forum and make your own determination of risk.

 

[Drone Master]

There is no way to turn off the bottom sensors on the mini 2. You would have to tape over the sensors to keep them from misreading the water at the altitude you are referring to. Although not recommended, you would have to rely on visual line of site and GPS to avoid going onto the water when flying that low. A minimum of 6 meters from the water surface is considered relatively safe. Any thing lower than that could cause the aircraft to want to land and thats where so many make that mistake and lose their drone.

 

[PHZ]

You could buy an rc boat, mount a Go Pro on the bow, and achieve the desired footage without losing your bird. Unless the client is paying you more than the cost of a new drone, I would walk away from that challenge.

 

[Yorkshire_Pud]

Very risky, that's too low to be safe, you'd have almost no time to respond to an uncommanded descent. It would be bad enough in a hover but if moving it's an almost certain swim.

 

[Zbip57]

I want to fly low over the water with a DJI mini 2 or DJI mavic pro. And by low I mean about 50 cm above the water.
{...] is the drone still stable?

Under perfect conditions the "Landing Protection" system will prevent the drone from descending closer than ~50cm (~2ft) to any detected surface, unless you hold the throttle stick down more than 85% to command an auto-landing. HOWEVER, there are many situations where that system cannot be relied upon to work properly.

Try it yourself. If you only partially hold the throttle stick down, the drone will slowly descend until the the infrared sensors of the VPS system detect that the drone is about 50cm from the ground. There the descent will automatically stop even if you're still partially holding the throttle stick down. But if at that point you pull the stick more than 85% down, the app will announce "Landing" and the drone will auto-land itself. Obviously that's not so good if the drone is over water.

Also the infrared height measurement is not to be trusted when over water. People will tell you that the infrared signal might penetrate the water's surface and instead give a false reading bouncing off the bottom of the lake, meaning it can't reliably prevent you from lowering the drone into the water if it thinks it's still higher than 50cm from the lake bottom.

See this thread from January for more info and videos.
mavicpilots.com/threads/yes-landing-protection-can-be-disabled-but.134162/

 

[hiflyer201]

If the sensors don't get you the illusion will. Flotation equipment is available.

 

[TimVL]

Under perfect conditions the "Landing Protection" system will prevent the drone from descending closer than ~50cm (~2ft) to any detected surface, unless you hold the throttle stick down more than 85% to command an auto-landing. HOWEVER, there are many situations where that system cannot be relied upon to work properly.

Try it yourself. If you only partially hold the throttle stick down, the drone will slowly descend until the the infrared sensors of the VPS system detect that the drone is about 50cm from the ground. There the descent will automatically stop even if you're still partially holding the throttle stick down. But if at that point you pull the stick more than 85% down, the app will announce "Landing" and the drone will auto-land itself. Obviously that's not so good if the drone is over water.

Also the infrared height measurement is not to be trusted when over water. People will tell you that the infrared signal might penetrate the water's surface and instead give a false reading bouncing off the bottom of the lake, meaning it can't reliably prevent you from lowering the drone into the water if it thinks it's still higher than 50cm from the lake bottom.

See this thread from January for more info and videos.
mavicpilots.com/threads/yes-landing-protection-can-be-disabled-but.134162/

Thanks for this explanation.
And do you have experience with a floating system underneath your drone? I’m considering to buy one.