Does anyone have experience with performing long distance fixed wing emergency landings with APM on board? Any problems with failsafe/RTH kicking in?
I fly medium/long range (~10km)/ low altitude (<1% of distance) in flat rural areas and I've always figured that if battery would run out I'd simply point the plane at a suitable field, stick the plane in FBW and cut throttle and glide it down. If i were to loose video 10m-20m AGL it'd be OK as FBW would glide it by itself the last few meters.
The other day i realized the obvious: when altitude gets low enough that my 5.8Ghz video goes, my 2.4GHz FRSky may well failsafe too - resulting in the landing being aborted, APM gain some altitude, and likely crash at a less favorable location. Worse yet, i may not even know where it went down unless it ascends enough for video to be re-established.
Is this something that has happened to people? Is there anything that could be done about it? Ideally it'd be nice to have a special "emergency landing flavor" of FBW flying mode that the pilot could enter just prior to executing the final descent; behaving like regular FBW except APM not allowing direct transition from this mode to RTL - but maybe the use case is too narrow to warrant such a feature?
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Thanks, I do use it as a backup for conventional FPV with APM set to Circle first then RTH after 20 secs in the case of loss of signal. All the times I've flown out of range the MP responds with "Circle" and I usually just hold my Tx above my head, regain control and know that I've gone too far.
How would APM know to land or glide instead of Circle when out of range?
I've had one battery go flat on me about two years ago on my return leg from a long flight, I could see my car in the distance but knew I wasn't going to make it, so as you said I just put it in FBW-A mode and went as far as I could, I landed fine about 200m away but in long grass, took about 10 minutes to find the plane in spite of knowing more or less where I had landed.
I suppose the easy solution is just to know how far or long you can fly and make provision.
"How would APM know to land or glide instead of Circle when out of range"
thats the problem. the only solution i could think of is what i proposed above: a specialty version of fbw which acts just like fbw but apm will NOT go directly from this mode to RTL even if requested to do so by rx (or circle - i had forgotten that apm does with some receivers). the only way to leave this mode would be to request any of the other modes - like regular fbw, manual, stab etc. the only use case for this mode would be to engage it just prior to an emergency landing.
yeah. its a bit convoluted and perhaps not on the top 10 list of most requested features :)
i agree regarding making provisions. it hasnt happened to me in 3 years but ive been close more than once and like to plan for the unexpected. i may look into how hard it would be to hack it myself
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