Tip over on landing

[Carapau]

I have just maidened my Skyjib and got three flights in. On the third flight, I landed the machine in GPS/Atti mode and it immediately tipped over to the right on touching down. Any ideas what might have caused this?

Here is some background. WKM single waypoint. Motors: Axi 4120/20s (they all seem nicely balanced). Xoar 15x props (balanced). Gains- all at 100 as I had yet to get to tuning these. 2-5 mph winds although mostly still, and about 6 degrees C. Idle speed was set in the middle and the landing areas was flat short grass. Many thanks for any insights.

 

[olof]

I tend to land and take off in Atti not GPS. GPS is really only accurate to 10' or so, for me at least. It seems better after flying for a while most of the time, but not always. Sometimes it will hold within inches other times within 10' or so, and it will change during a flight. Probably due to trees buildings etc. I find GPS is more accurate the higher up you are. Right at ground level it is at its worst, for me anyway.

My point is that sometimes GPS mode will make a small correction and when landing and taking off this can cause drift, and a bit of drift will cause a tip over if you are on ground with a lot of friction like grass. Even in Atti or manual a sudden gust can cause lateral drift enough to tip over a multi with high landing gear. Landing on a slippery surface like ice is much easier than a grabby surface like grass or sand/gravel.

 

[Carapau]

Okay, that makes sense. My landing was smooth but the GPS might have expected to carry on descending so to speak and thus put in a correction- would that be the gist of it? If landing in Atti or manual is recommended then I am very happy with this.

 

[hover.ch]

How heavy is it, your Skyjib? I could imagine that your gain settings are too low.
My AD-8 tipped over during launch, more than once! It was because of too low gain settings!

 

[Carapau]

That could also be this issue as my gains are all still at 100. I'll have a play next time starting at 200 for each gain I think

 

[OneStopRC]

Too high a gain will make it extremely twitchy, will make it respond a lot quicker to the slightest input (less stick). If I was you, I would work up from the 100 maybe go to 130 and increase from there on out.

 

[dts]

Couple suggestions: do you have a high center of gravity? Landing skids may be too short?

 

[hover.ch]

How heavy is it, your Skyjib? I would use the table on one of the last pages of the WKM manual is a rough guide.
My current gains for my 6kg AD-8 are: 240/240/200/200/220/200. These gains work pretty well, for a 5kg MR they are already too height, I noticed.