RTH and then...Crash

fastsmiles · Jul 28, 2014

I was doing some videos within a small area and pushed the battery to the limit, 16% and then triggered RTH. The P2V+ was less than 100 yds away when it began its return, hovered, and then began to descend about 20 feet from the home point. A nice vertical descent (winds ~5mph). Everything looked fine and I began videoing the V+ with the plan of filming the descent and landing. When it touched down, instead of shutting off, it began to ground hop in an effort to return to the launch point. It almost made it, but wound up flipping over onto its back. No damage, but it made me wonder why the return point was off by so much and why it tried to move across the ground to the original take off point after descending. I've had no problems with RTH in the past, although I seldom use RTH.
[youtube]http://www.youtube.com/watch?v=j63iW4e5JQE[/youtube]

Pull_Up · Jul 28, 2014

Looks like it was coming in to land in a little hollow in the ground that caused a big ground effect - possibly exacerbated by that plate you've got fitted to the legs there. If it was low on battery it may have got to the point where it was in an auto descent to save the whole thing from just dropping out the sky on the return to the home location. As a failsafe procedure it did its job of bringing the craft down rather than drop, but you can see it floating in ground effect rather than settling down.

reginarh · Jul 28, 2014

After a few tumbles like your's, I now only do hand catch landing. It's easier on the prop's and me. Whewwww.

Dirty Bird · Jul 28, 2014

You stated that you triggered a RTH at 16%. At 15%, it would reach the second battery alert and it would automatically begin to descend, unless you've changed your second battery alert threshold. The ground hop on auto-land happens a lot, which is why I always take over and perform the actual landing manually. Fortunately no damage.

Hovtech · Jul 28, 2014

reginarh said:
After a few tumbles like your's, I now only do hand catch landing. It's easier on the prop's and me. Whewwww.

I do hand catches too. I never let it land itself for the reasons in original post.

happydays · Jul 28, 2014

I have to say, I laughed at it hopping across the ground like that. Bad man! Bad man!

fastsmiles · Jul 28, 2014

Pull_Up said:
Looks like it was coming in to land in a little hollow in the ground that caused a big ground effect - possibly exacerbated by that plate you've got fitted to the legs there. If it was low on battery it may have got to the point where it was in an auto descent to save the whole thing from just dropping out the sky on the return to the home location. As a failsafe procedure it did its job of bringing the craft down rather than drop, but you can see it floating in ground effect rather than settling down.

I have done plenty of landings with the "plate" in place with no problems prior to this.

fastsmiles · Jul 28, 2014

Dirty Bird said:
You stated that you triggered a RTH at 16%. At 15%, it would reach the second battery alert and it would automatically begin to descend, unless you've changed your second battery alert threshold. The ground hop on auto-land happens a lot, which is why I always take over and perform the actual landing manually. Fortunately no damage.

That sounds like a reasonable evaluation. I usually hand catch, but I wanted to video the landing as part of the video I was making. Got more action than I planned on.

BlackTracer · Jul 28, 2014

The only time I ever had an RTH landing, was a test by me on my original P2V. On 1.08 mind you. I have had plenty of RTHs since then but I always take control and land it myself. Mine did not skip like that, but instead bounced up and down like it was being held on a spring. It did finally land, a little harder than I would like. But the vision is a beast so no harm done.