Oh what a silly billy ...

[Hands0n]

Thats me, before anyone asks.  Daft as a daft thing sometimes! And today it has cost me one rotor arm - not lost one of those in quite a while now, plus two carbon reinforced ABS props (think I may have to buy these in wholesale!).

I took the 450 Firefly + APM 2.5 out today, having spent a bit of time this morning in the garden adjusting the PID of the APM (Stabilise, Loiter and Alt Hold).  Ever since 3.1 and giving it an Auto Tune it has been a bit skittish, overreacting to either the controls or the wind, particularly in stabilise mode. Loiter sees it doing an Irish jig. And alt hold looks like its got a case of Parkinsons!  Not uncontrollable by any means, but it doesn';t look very tidy or professional.  Besides which, I don';t want to get used to flying it like that and then not be able to fly something that is well set up.  So I set the various PID on a rotary switch on the TX and spent two hours adjusting until I was happy - and it was a breezy morning so a bit of a challenge anyway.

This afternoon I took the Firefly out for a proper sortie around my fave local farmer';s field.  At ground level the wind had dropped to a gentle breeze, but at any moderate altitude it was considerably stronger.  A great test field for the afternoon.

First 2200mAh 3S LiPo and I cocked it right up!  I took the Firefly out to about 50m from position, set it to Loiter, then hit up RTL - its been a while since I field tested it and since then Auto Tune and lots of Parameter hacking.  It behaved impeccably, which is more than I can say for myself. Up it went, 15m and held, then rotated to launch position and travelled over to me. Overhead it rotated to original launch heading and started its descent. About 4 meters altitude I, for Lord alone knows what reason, reduced the throttle to zero and pulled the switch out of Loiter and flicked back to Stabilise - thinking that RTL would continue.  It didn';t. Gravity took over and the ground came up sharply on one of the rotor arms, snapping the end off and seeing off two props. 

Now I could have sworn that RTL trumps everything else. But it seems apparent to me that the last switch mode applies, regardless of whether the APM is in RTL or not!  And thats plain daft!! Daft, I tell ya!

Fortunately, my flight box carries a number of critical sprares - such as rotor arms and spare props - and so within 10 minutes or so I was fixed up and ready to go again.  I then spent the next 90 minutes and squillions of LiPo just having a right ball. It was excellent fun.

So a lesson to all APM fliers from someone with practical experience - when in RTL leave the TX switches alone until it has landed safely, or if you actually want to take it out of RTL and do something else (which it will willingly do).  Oh, and never, ever, never zero the throttle before changing mode switches - the next mode may rely on some throttle to keep the aircraft airborne 

Piccies:

[attach=1]

[attach=2]

[HowDoIfly]

Oooh, lesson learnt and all that. I';ve had a zero-throttle brain-fart but fortunately, was some distance up so recovered by upping the throttle in time.

I';m interested what setup you have to think that changing flight modes will be ignored if RTL was chosen before?

[Hands0n]

With APM 2.5 and Arducopter 3.1 if you hit up RTL it will override any flight mode the aircraft is in and begin to execute the RTL routine.  However, if midway through the RTL you flip the mode switch to something else, it then goes into that mode!

I have RTL on a switch all by itself, using Ch.8.  The three-position mode switch is mixed in with Ch.5 (Gear) to give me a possible six selections. The gear switch is acting like a sort of shift key. So, for example, with the mode switch all the way up, and Gear switch down I am in Stabilise. Flip the Gear switch only and I am in Stabilize+Super-Simple.  Middle position is Alt Hold, Middle+Gear is Drift (I use that selection to experiment with modes or Acro), Up position is Loiter, Up+Gear is Land (makes sense to me!).   

So, it is possible to select RTL independently of anything else, and that will override everything else.  But, with the RTL in active mode, change the 3-position+shift switch and the mode applicable to that combination overrides RTL!  And I don';t believe that should happen. 

I need to try and video a tightly controlled series of tests to show that happening.

[Gadget Man]

Ardupilot will do what it is told when it is told.

You need to sit down in front of mission planner with your transmitter in your hand and familiairise yourself with the flight modes while connected safe via USB.

Learning how your flight mode switch/ switches react when it';s in the air is not a good idea.

I really am sorry to be critical but you should know this stuff before take off.

[HowDoIfly]

I have the same setup, RTL on Ch8 Yes, RTL should override any other flight mode but if you look in MP > Flight Modes, you will see that subsequent change of flight mode will override RTL also. I don';t know if it';s intentional but I hope so! Bit of a big boo-boo if it wasn';t.

[kilby]

If it';s in RT (via separate switch or not) and you change mode then it will switch to the new mode, like any Unix box it will assume you wanted to change mode.

It may be a decent default option for no mode change when triggered by the panic switch but currently it';s simply treated as an ordinary mode change

I did something similar with the throttle cut switch once, and quad quite like throttle cut disabled in RTL mode

[Cloudbuster]

Dont bash yourself danny we all do daft s**t sometimes LOL !!! With the number of changes made to the APM over the last 12 months its a wonder we know what we are doing with it at all.... Great FC but some of the updates have caused all sorts of problems for people. I am just learning how totally unflyable the Naza Lite is in manual mode !!!  nearly totally destroyed a brand new quad yesterday by flicking it into manual by mistake LOL ... I just love this tech we will all look back and laugh in a couple of years about the rubbish we used to fly LOL...

Regards rob  ::)

[Hands0n]

Learning how your flight mode switch/ switches react when it';s in the air is not a good idea.

I really am sorry to be critical but you should know this stuff before take off.

I know exactly how the APM (more accurately Arducopter) behaves in this respect.  But I also pilot Naza M Lite and occasionally the synapses and muscle memory react inappropriately.  Sitting here in the comfort of the settee I can recall exactly testing the behaviour out in Mission Planner. 

The mistake, however, was not changing modes but zeroing the throttle.  Had I not done that the APM would simply have flipped to the next mode and continued flying. As indeed it did in later flights.

The tale is offered here to hopefully advise and inform those who may not be quite as familiar. 

[HowDoIfly]

Best not mention the times when I';ve hit RTL and the quad completely ignored me and just began drifting off in a random direction. And if you have a talking Taranis, it lies!