I thought I've had just about everything bad happen to me already, until today, my lucky day, I had a FLY-AWAY! I cannot express the terrifying feeling of seeing my $8k bird and camera take off into the distance with no control.
Holy crap. Now that is scary, Tim. Does your system record a GPX file by chance? Any idea what caused the flyaway -- just the lack of the transmitter being turned on? Also, did it crash or more or less soft-land? I guess there's a strong argument for having the GPS coordinates show on the OSD too. Andy.
OOOO.. thats why i fly only in manual... ...! These things scary me...!! Its better to post this on hoverfly tooo.!! I am happy that everything is ok..!
I think it records the flight log, but if you notice, the distance to home in the lower L corner keeps jumping back and forth. I know exactly what went wrong, not sure why. After I armed, the ezUHF Tx DIED. Would not power on again. My failsafe was set to a little above hover throttle and RTH. RTH has not been working since the latest firmware upgrade/ external mag compass install on the HF. So, upon failsafe, it went immediately to 55% throttle and drifted with the wind. SO the lessons I learned- Probably better to set a failsafe throttle below hover-point. Might be better to set it to Alt Hold. ? Having a friend there with a car nearby was a lifesaver. A monitor that shows the image, no matter how much static, is worth its weight in gold-plated FF parts. Thinking that something could never happen to your solid transmitter setup is naive. After, I went and bought 3 lottery tickets. I got so lucky that it landed in soft grass only a few feet from the water, and even though the fpv antenna was on the ground, I got a tiny signal by the road, which led me to it. While I did bust two tubes in the gimbal, everything else was unharmed. Oh, and the hoverfly still fly's really smooth. Especially with nobody controlling it.
But what do you have your failsafe set to do? If you ever lose your Tx link and it stays in manual it is going to drive itself fast into the ground and the damage will likely be much worse.
So, with this behind me I would like to turn it into a discussion about failsafe settings. Even if RTH was working, it still would've climbed to at least a few hundred meters and the landing, caused by low battery, would've been very fast. Essentially a level crash. I probably would've preferred this to the 3.5 mile chase. Lol. If I set the failsafe throttle to descend or just below hover, what if I'm over water? I could set it to alt hold, which would probably cause a quick crash if it was on the ground, but if it is already flying then it might maintain that alt until being overwhelmed by a low battery and drop like a stone. Times like these I miss the wkm- but when I fly it... So for hoverfly owners (and MK too?) what is the BEST way to set your failsafe?
With MK, it's relatively easy to setup the fail safe throttle. MK can understand the hover gas automatically and you can set the gas, for instance, to %90 of the hover gas and it descends fairly slow. It's also very important to disable the tx/rx systems fail safe. The electronics handle that pretty well, at least MK and DJI WK-M. For MK, another good option to use is not allowing the kopter to arm unless it gets at least 6 satellites. But this option prevents the kopter to take off in indoors. And a OSD video recorder at the ground station is always useful I think.
I've not confirmed this myself, but if you're using MK boards with a MX-20/GRxx radio setuo, does it downlink the GPS coordinates to the MX-20? If it does, then you'd have the GPS coordinates in the MX-20 (at least the last known ones before it flew out of range). I also use a Walston Retrieval system on the copter. The MODA 2438 MVS-F Quad transmitter is tiny and the receiver has a Yagi antenna so that the range is of the order of 5 miles ground-to-ground (50+ miles line of sight). Fortunately, I've not had to test it at that extreme range yet. I figure it's cheap insurance, although you do have to futz with watch batteries and testing it pre-flight. I don't put the Yagi antenna on the Rx for preflight -- the chirp signal is strong enough to turn the Rx precisely without any antenna. Andy.
Yes scary stuff! Glad you got it back. I too had a fly away earlier this year with MK and after come home was activated it took off to someone else home. Ended up being the GPS battery nearly dead and not enough satellites acquired ( the not arming without minimum sats fixes that mistake now). Thankfully on the way to wherever it was going were some giant trees that stopped its flee. Come home with transmitter loss worked in testing a few times but I won't forget the feeling in the first few seconds when it went awol.
It was a combination of RTH not working, the throttle too high for failsafe, and the voltage suddenly dropping on the trainer port output, which powers the ezuhf, sending the rx into failsafe just after being armed. In hindsight I could've used a plug from the downlink and powered the uhf externally to regain control. But we were so panicked trying to look for it, I didn't think of that.
Thanks for sharing this us. Can you tell me what RTH stands for? Sorry for the newbee question. Also what settings did you have the throttle in failsafe? What did you change them to?
More accurately, with the MK Boards, the "RTH" is known as "Coming Home" or "Come Home." This is the option set in MK Tool and not in the MX-20 transmitter. I have not set up the MX-20 transmitter as it's "fail safe" seems to be "freeze all controls at current settings" which is not what I'd want to happen. The MK Boards fail save seems far more rational. For MK Tool/MK Boards: 1. You need to set a Coming Home altitude that takes into account where you're flying. The copter's going to ascend/descend to that altitude, hold for a few seconds, then go into coming home mode -- in a straight line to "home" (the last place where you powered on the motors after it had a GPS fix -- be careful to power the motors on only after the GPS fix otherwise you might have last week's "home" position!). You need to clear trees and buildings that might be between you and the bird's home position. 2. The Emergency Throttle is a percentage of what it takes to hover. As far as I can tell, this the actual "throttle necessary to hover" is determined by the MK Flight Control board (or perhaps the Navigation Control board), so that what we need to set is the percentage -- which is really the answer to the question: How fast do you want your bird to plummet out of the sky? I have mine set at 90% but I've not tested it....I think I need to be out on the Alvord Desert (a dry lake bed 11 miles wide, 22 miles long) to do a good test....then I can tear across the dry lake bed in my truck after the bird if it takes off for the next county over..... Andy.
I had mine at 95%. Still couldn't bring myself to let it come all the way home and then descend. I did send a question to the the QC who did test it all the way to the ground. The initial descent was, in my words, like a rock and truly terrifying. Then it slows down and continued to descend. So it it not a linear descent rate, rather logarithmic. And if you haven't tried RTH it to is very exciting. Unless you make some adjustments the craft will pitch over about 45-60 degrees like it is going out of control, comes towards you at 15m/s which is screaming fast, will climb/descend to your come home altitude. Very startling the first time you see it. SERIOUSLY scary. The ground speed can be adjusted to a more sedate rate, I forget which setting that is. So find a big, nice long field, fly it out about 1000 feet, turn on AH and PH, pop your favorite beverage and then throw that Come Home switch. Remember to breath..... One note is NOT to setup up failsafe on your MX-20. Read that someplace.
I use the hoverfly board which does not have an ability to set an altitude for RTH, so I chose to set the failsafe throttle at a little above hover for a half-used battery. So on a full battery it was a good deal above hover! As you can see by the 1-2 meter per second ascent. Now,I think I will set it to a slow descent on a half used battery, but if I'm flying over water I will reset to a hover throttle. The main thing is to get RTH working again. Something to do with my compass, they say, which is also having issues. How ironic that the partial cause of my fly-away was the GPS board, which I only have for the safety of RTH! I will take precautions so I never lose the transmitter power again when using the ezuhf. For now I bought a new 8fg.