My Bucking Phantom - Failsafe in Action

[Dartmoor Dave]

No not a misprint in the subject heading. It was something that happened to my P2V+ on my first ever failsafe return to home, on my first day flying up on Dartmoor in September this year. Before that I'd been learning in a more constrained area locally so hadn't seen failsafe working.

You can see it in "bucking" phantom in action on the video up on youtube, about half way through. I've been told that it is a normal action as the copter flies out of RC range. Have any of you guys experience anything similar or have an explanation as to why it might have happened?

http://youtu.be/4RS5QgwMABg

I was flying a few hundred metres to a spot on Dartmoor called Leeden Tor when I received a "Coming Home" message and realised failsafe had kicked in. At a guess the P2V+ was about 450 metres from my home point when it happened, too far to see what was happening in detail, visually. I let my P2V+ fly back and then recovered control to land it in an area that was relatively clear. It wasn't until I'd downloaded the video that I noticed the "bucking" action. I think I was just out of fpv range when failsafe triggered so hadn't seen it on my smartphone.

If you are wondering what the brown stick is, in shot from time to time, it is part of a short length of bamboo cane I'd ducktaped to each landing strut to give a little more stability when landing on rough ground. The bamboo protruded 3 cms front and rear on each horizontal strut. I've subsequently shortened the left forward section to keep it out of shot when videoing, It is rigid, actually works and does offer much more stability for both take off and landing on rough ground. It also fits inside my v2v+ backpack nicely.

Although the prop guards were definitely useful in my first few weeks in my constrained learning area I soon removed them as they appeared in the videos too much and also didn't fit the backpack I use and I didn't need them in any case.

Once I'd learnt how to fly the phantom with more confidence I also moved across to NAZA-M operating mode, the benefits that NAZA-M offers has been recounted on here frequently and I can endorse the many advantages of using NAZA-M

 

[msinger]

Maybe the signal kept going in and out while you were attempting to control it -- thus causing the perceived bucking.

 

[Dartmoor Dave]

Thanks msinger,
Yes I can see the logic there, I was still flying it towards the Tor when it was at the limit of the RC range, and I guess at the margins then the in range / out of range fluctuations could well result in the bucking action the video shows.

 

[saao]

Have you done any mods to your quad I have seen this happening twice with me never with standard equipment but it happened because the bird side mod wasn't done properly meaning I did the splice method and screwed up. It's definitely a matter of range frequency fluctuations.

 

[Dartmoor Dave]

No saao, it is an out of the box p2v+, it had the prop guards and the very light bamboo landing gear extensions I mentioned but no internal mods to either the P2v+ or the RC hardware

 

[rbhamilton]

Hummm... I've had lots of these RTH's. I've never seen any strange bucking. It usually comes to a stop. Waits a moment. Does a slow rotation then heads home smooth as silk. You were near a hill... was it windy? Perhaps some kind of wind gust coming up off the hill or something?

 

[bergenfelter]

Try it again without prop guards-those things introduce a lot of control instability. Cratered my first phantom because of those darn things and a good case of VRS. FWIW.

 

[Dartmoor Dave]

Thx rbh, yes there was the possibility of an updraft as I was flying up a hill towards the Tor but it was a quiet morning with wind < 10 kts.
Re removing the prop guards, bergenfelter, they were removed a few days after that flight although not for reasons of possible instability as I hadn't noticed any TBH. I felt I didn't need them any more, they got into the camera shot too often and I couldn't use my backpack with them fitted.

I'll repeat the flight when I'm in the area if weather conditions are similar and see what happens. Next time I'll also capture the smartphone screen as a video too so I can see just what information the vision app is giving me.

I'm find that is an excellent information tool, incidentally, as watching it at home post flight I get some very useful data from it, well worth installing some screen capture software on your control smartphone/ tablet if you can IMHO

 

[PhilAnderson]

Dartmoor Dave, it looks like you need to turn off FPV mode in the app. That won't stop the bucking, taking off the guards will probably accomplish that, but with FPV mode turned off, you won't see it. The video will be smooth as silk, wind or no wind.

 

[Dartmoor Dave]

Thx Phil Anderson, made me smile anyway. What is that saying
"What the eye doesn't see - you don't worry about" ,
at least until you get back home and look at the video and that at the time wasn't quite "as smooth as silk" during the bucking for sure.

As a matter of interest it hasn't happened for the last three months since I removed the props and I've had plenty of out of control range signals since then, so the prop guards could well have been the culprits as one or two have suggested. Thinking about it, those may not have been the cause though as about the same time I also unchecked fpv view on the vision app to the gimbal assisted smooth video view. I could always revert to fpv mode flight and see whether it continues to buck at edge of control range with no prop guards

 

[robinb]

I think with the blade protectors on the "bucking" is caused by the wind as you neared level with the ridge on hill.

I expect they are acting like sails.

I would remove them.

The camera is quite steady so I would not be worried about this.

 

[Dartmoor Dave]

Interesting idea Robinb, that might well be the cause. As I mentioned earlier in this thread, I removed the prop guards shortly after the incident in the video, but only because I wanted to use my backpack and couldn't use it with the propguards attached. No problem perceived with bucking since then.

 

[bergenfelter]

Thx Phil Anderson, made me smile anyway. What is that saying
"What the eye doesn't see - you don't worry about" ,
at least until you get back home and look at the video and that at the time wasn't quite "as smooth as silk" during the bucking for sure.

As a matter of interest it hasn't happened for the last three months since I removed the props and I've had plenty of out of control range signals since then, so the prop guards could well have been the culprits as one or two have suggested. Thinking about it, those may not have been the cause though as about the same time I also unchecked fpv view on the vision app to the gimbal assisted smooth video view. I could always revert to fpv mode flight and see whether it continues to buck at edge of control range with no prop guards

I will always continue to say the prop guards are garbage and cause more damage to quads and property that they are worth. The very last incident I had with them I was teaching my 12 YO to fly my p2v+ - it was hovering about 30 m up and and the p2v started bucking like a bronco (like in your videos) - the bird came straight down (you could hear the motors screaming trying to compensate) and >smack< on the pavement. Thank goodness my daughter or I was not hurt - she was upset that she caused the accident - I had other incidents with the prop guards before and this time threw them in the trash (actually recycle bin - hopefully they are a nice addition to someone's composite outdoor deck surface by now). That was about five hundred flight hours ago and never had any issues like that since.