Phantom 4 spins with pontoons on

[Dpanetta]

I am hoping someone can give me some advice. I intend on flying my P4 over water, and I decided to create a set of pontoons for it so it would not sink if it loses power or decides to land suddenly. The pontoons were machine to exacting specifications and they are both identical in size angles and weight. After the P4 has been aloft for about a minute with no stick input, it starts spinning and I cannot control the direction in which the P4 is aiming. I can still land the P4, and I can still pitch it side to side, but I cannot stop the spinning. I have included a couple of pictures so you can see the pontoon configuration. Things that I have tried so far are adjusting the sensitivity and gain settings in the DJI GO app, and adjusting the flight mode to the P, S and A modes. None of them seem to have much if any impact. Any suggestions would be appreciated. I would really like to be able to fly my drone above water, but I am not willing to take the risk if the drone flight cannot be stabilized or if I have to go without the pontoons. I have read too many horror stories about people losing their drones to the ocean, lakes, and pools because of issues that may or may not have been user related. Thanks.

 

[N017RW]

What's the black thing strapped to the left rear gear?

 

[Dpanetta]

What's the black thing strapped to the left rear gear?

It's a Marco Polo tracking transmitter. I have played with it and can track it down from up to a mile away. Hopefully will never have to use it for its intended purpose. It does not impact flight performance when the pontoons are not attached.

 

[N017RW]

From where I sit, maybe you are experiencing some aerodynamic forces causing a spin. It's unlikely your a/c would remain upright after a rapid descent so the flotation should just assure it won't submerge. Try reducing the size of the pontoons.

 

[MapMaker53]

It depends on your definition of "exacting specifications and they are both identical in size angles and weight". To me, it doesn't look to be something that can be exactly identical and mirror images to each other -- at least not to the accuracy I believe you require. The SLIGHTEST difference in shape or angle will not only change the pin-point center of gravity location but also how the prop wash hits and deflects off those pontoons. The slightest difference in prop wash deflection will cause your Phantom to start yawing in one direction or the other. I suspect that is why it is spinning.

They clearly are not constructed identical.

 

[Meta4]

I intend on flying my P4 over water, and I decided to create a set of pontoons for it so it would not sink if it loses power or decides to land suddenly.
... I have read too many horror stories about people losing their drones to the ocean, lakes, and pools because of issues that may or may not have been user related. Thanks.

Falling from the sky is about the least common incident that caused the loss of Phantoms.
Forget those horror stories and forget those silly "floats".
They are really sails and are going to seriously reduce your Phantom's flying ability and aerodynamic properties.
Rather than enhancing the safety of your Phantom, they are more likely to contribute to its loss.
They are going to reduce your Phantom's speed and flight times, increase potential to be blown away or unable to deal with a headwind.
They wouldn't keep the Phantom dry in a fall from the sky and you'd still have to get a boat and somehow find the floating remains in that hypothetical situation.
If you are dealing with salt water, all that would be recoverable would be the props and SD card anyway.

 

[Dpanetta]

From where I sit, maybe you are experiencing some aerodynamic forces causing a spin. It's unlikely your a/c would remain upright after a rapid descent so the flotation should just assure it won't submerge. Try reducing the size of the pontoons.

I think you are onto something here. I took a video of the drone hovering with the pontoons on, and I can hear the motors fighting each other. The pontoon frames are really what are identical, and the amount of flotation I added could float 4 drones. I will be changing the flotation to a thinner mayerial. Some hot water pipe insulation wrap should work nicely. If flight is still not stable, I think I will take a slow motion video of the drone with a smoke source above it so I can see what is happening to the prop wash.

Some great thoughts guys! Thank you.

 

[Erised]

Every thing Meta4 says goes for me too. I can understand you wanting to make your craft safer but this is a crash or a fly away caused by the wind blowing it away waiting to happen. In a water landing with small waves the craft will flip and get wet any way. I have a getterback for fishing rods fastened to the landing gear, they are small, super light and don't affect flight dynamics in any noticeable way, if you are less than in 100 feet of water a floating marker will rise to the surface with a 10 lbs test fishing line and you may be lucky and see it and recover what ever may be saved. In order to turn the craft 2 of the motors with the same pitch will turn faster or slower then the other 2, the way the floats are made will deflect trust and cause your craft to spin.

 

[Hstarin]

After reading the responses re the "pontoons" no one has mentioned the Marco Polo tracker attached to the leg of the drone. Manufacturer says It weighs 50 grams, which is almost 2 ounces (1.76 to be exact). Go to a bait and tackle store and pick up a 2 ounce lead fishing weight. It has some heft to it. So couldn't it be that even without the "pontoons" this drone would act erratically due to the offset center of gravity from the tracker? If I used one I'd mount it as close to dead center on the drone case as I could.

 

[N017RW]

After reading the responses re the "pontoons" no one has mentioned the Marco Polo tracker attached to the leg of the drone. Manufacturer says It weighs 50 grams, which is almost 2 ounces (1.76 to be exact). Go to a bait and tackle store and pick up a 2 ounce lead fishing weight. It has some heft to it. So couldn't it be that even without the "pontoons" this drone would act erratically due to the offset center of gravity from the tracker? If I used one I'd mount it as close to dead center on the drone case as I could.

Won't cause a spin.

 

[Dpanetta]

I've had the Marco Polo tracker attached to the drone since day one. It has never caused an issue. Thankfully, it has never been used yet either. That is, except for playing with it.