Flying down a small creek this afternoon. Wanted to do some 3-4ft off the water stuff. So I disengaged VPS for this. Because you get the bird rising on it's own as it gets down close enough to cause the water stirring. And this would cause my bird to rise up into tree limbs hanging out over the creek. So with VPS off it worked fine as far as the flying went. No rising at all as I flew some passes. But when I would stop I was getting a lot of sinking down mainly and would have prob sunk all the way and hit the water if I had let it. But I did not take my eyes off of it and throttled it a tad and no prob. But in a hover it was kind of eratic just slowly going up and mostly down when hands off with VPS turned off. When I let the bird get 150ft or so away from me I was kinda afraid to stop and come back thinking it may jump up or down a little and land in the creek! Has anyone else had the same reaction with their bird when you turn off VPS?
VPS Question over water?
- Thread starter KevMo Photog
- Start date
alokbhargava
Premium Pilot
VPS is designed to maintain altitudes at low heights and if you turn it off and fly low, it's like manual control. If it's not seeing Satellites, it will then swing horizontally too.
You had a courage to take it that far and brought it safely back.
You had a courage to take it that far and brought it safely back.
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I appreciate the info alokbhargava! Seems strange it would fly perfect and not vary in altitude but then when stopped in a hover it wants to move up and down. Just didn't want the VPS to cause it to balloon on me and get up into some branches on overhanging trees when it gets down to within 6-8ft or so. But I def did not take my eyes off of it while doing this so I felt pretty safe because it was responding to everything I would give it.
Hallo,
I read with interest your post and I must say that I keep VPS on when flying low over sea (no trees though),
However, what happens to me is that P4P doesn't recognize "water" below it (several attempts at different speed) ... despite P4P it's supposed to detect water
(yes, I had the option activated in the app).
May I ask what is your experience with water detection?
cheers
I read with interest your post and I must say that I keep VPS on when flying low over sea (no trees though),
However, what happens to me is that P4P doesn't recognize "water" below it (several attempts at different speed) ... despite P4P it's supposed to detect water
(yes, I had the option activated in the app).May I ask what is your experience with water detection?
cheers
When you say it doesn't recognize water with VPS on, do you mean that it is losing altitude as you travel forward or backward? My experience with VPS on is that once you get down at 6-8ft above the water and its wash its stirring the water some the bird will balloon sometimes 6-8 more feet higher. As long as you stay just higher than that I don't see any problems at all. But I'm wanting to fly closer for the shot say like 3ft off the water. So VPS will not let you do that with consistency. So I turned it off. But while hovering in close to me I noticed that it was just slowly drifting up and down and mostly down and would fall right in the water if I let it. It got to within 2ft and was still going down until I juiced it up a tad. So warning without VPS on you better be watching your bird in close to you at all times because it will just slowly drift and drop right down in the water.I used this in this case just for a shot I wanted. I didn't want it to balloon with VPS on. But if I were flying out over the sea I would just leave VPS on and not get closer than 6-8ft and your good. Nothing to worry about if it balloons up on you.Hallo,
I read with interest your post and I must say that I keep VPS on when flying low over sea (no trees though),
However, what happens to me is that P4P doesn't recognize "water" below it (several attempts at different speed) ... despite P4P it's supposed to detect water
May I ask what is your experience with water detection?
cheers
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It seems counterintuitive that the bird would drift lower over water, the closer to the surface it gets. The barometric altimeter is likely to measure a lower altitude than actual close to the water surface due to cooler air temps. So why would it drift lower? Should be the opposite.
Not sure why Roamer105. But trust me I let it hover at 6ft with VPS off and it just continually went up and down but pretty slow. With VPS on as soon as you get close enough to agitate the water some it balloons up on you. No problem as long as their is nothing over it's head to balloon into!
I only disable VPS over water when it's moving such as rapids in a river or waves in the sea.
Flying over calm water with VPS active has never caused me any issues.
Flying over calm water with VPS active has never caused me any issues.
Interesting BriG! When I try to fly a slow low pass over calmish water it will rise when it churns the water pretty good. So like if I wanted to fly under an 8ft tall small bridge if it ballooned it would be right up into the bottom of the bridge. Any suggestions for best way to do that? I had good luck with VPS off flying that low but had to watch it when you come to a hover as it slowly goes up and down then.
Yes I thought I had seen this somewhere online but I can not find any info in the manual.
How does it fly when you are in ATTI mode? Or were you already in it? If you were in P mode I wonder if you had some multipath issues with the GPS signal. Does it use GPS altitude plus barometric altimeter in P mode to determine its height and stay level or just the altimeter? Id think it would use both in that mode and compare and if so I wonder if maybe a combination of multi path and altimeter malfunction/miscalibration? I had a Syma X5HC that liked to do the up and down thing when it was warm outside. It used altimeter to keep it level and when it would get to these warm spots where the sun hit it would lose altitude and then I'd bring it up and it would then start to gain. Craziest thing. Anyways please try your bird in a shop or enclosed area with VPS off and let me know if you still have that issue please.
Take care,
Jesse
Very interesting - I've never hovered low over water, only flew over it. Maybe it's only when we initiate a low hover and the surface of the water is disturbed by the down wash of the rotors that VPS detects it.
I will def try that inside of our studio Jesse. I want to know as well what is causing it go up and down with it off. My be just normal for it.
It could be. However I feel that when I have it 20 feet in the air it's so stable. You know what I mean? I feel like I could probably set a drink on it. What was the outside temperature when you were operating at the creek? Any idea on the humidity level? I'll test in my shop tonight as well and report back to you. GPS is weak in the shop so the Phantom always seems to be using Vision in there. I will go to 5 feet and disable VPS and monitor. I will then observe the same in ATTI mode. Hopefully she won't drift as soon as I disable VPS. Since there is no wind in the shop we should expect her to stay pretty stable without control input right? The only thing would be any propwash or whatever type of other effects that could cause drift which I am not really familiar with but the change in elevation is what I will be also observing for as well. These are good things to know for the future. Stay tuned.
Jesse
Jesse
I found the YouTube video again where I had seen it. You have to try to auto land on the water. Of course I'm sure we would never try this but I guess that's how it will give you the detected message can not land.
It's towards the end.
It will def drift a tad in Atti mode inside K9VXV. But not much. Just don't take your eyes off of it. But it will stay dead still with VPS on.
I tested and was able to reproduce before sundown but I had interesting results. There was a large rain cloud at about 7:20PM but the sun was shining through on the other side of it. There was no rain at this time. I went up to around 100 feet and roamed around. It started to rain, I'd call it a very light sprinkle, almost like enough to turn your windshield wipers on for and then the drops started to increase and so I brought it about 20 and was hovering over my driveway that slopes upward and it started to do the bob up and down like it was almost trying to take a quick look at the gravel In the driveway and then fly back up. It only deviated about 7 feet in each direction but I was in P with full satellite so I thought maybe it had something to do with the humidity? It's 98% out at 48F. Not too much drift in either direction just loss and gain. So I ran to the barn and then to the shop and continued in there after making sure the Phantom was dry which it seemed to be with just two small spray drops on the top. I started the test at around 10 feet in P mode with 5 satellites. The Phantom is flying in OPTI mode with Vision in the left hand corner and yellow bar at the top. It's flying very stable at this point. I then land and disable VPS and bring it back to same height. It shows it's in ATTI mode with VPS off and GPS off. So I wonder than when you disabled the VPS to fly under the tree branches you must have actually been flying in ATTI mode with GPS off. When I flipped the switch on the remote to A mode I had the exact same behavior. With no wind in the shop I wondered why it was so squirmy. Sure the VPS was off but why would it drift so bad and bob in elevation? So I brought it up to about 20 in the shop and it stopped drifting so I was thinking maybe the wash from the props is causing the drift because the air was pushing off of the things in the shop surrounding it? Anyways I will continue more testing and let you know. This is good stuff to know I think. Wouldn't want to lose my P4P over something stupid I didn't know about.
Jesse
Great test Jesse! Now I did not experience the bird acting like it is in Atti mode when I had the VPS turned off. It just drifted up and down without any side to side movement at all. And I was in P mode too. It never said it was in Atti mode. So GPS was holding me steady in a column but not steady up and down.
