Simon Hall 2 Posted July 27, 2015 Share Posted July 27, 2015 Had a spectacular crash on Saturday with my Radian. With nearly 1 year flying and very many flights with no issues, I totally lost control of my plane at about 600ft. It rolled over suddenly and went into a full throttle nose dive. I could not do anything, just watched in horror as a spectator. Luckily the plane came down close by. My velcroed Mobius camera broke loose at about 200ft but I luckily found it nearby and with no damage. The motor was burnt out and the ESC totally fried. The cockpit was a smouldering smokey mess and the fuse is WAY beyond gorilla glue! I disconnected the lipo right away, but was a bit nervous with all the smoke and sizzling! I have a spare new fuse anyway which is good and the wings survived untouched. I am hoping it's just a new motor and ESC. I just can't understand how I could not shut off the motor and control the plane. I chucked it in the boot in disgust and have not had chance to test lipo, RX, servos and other bits yet. They all look visually ok, but I'm worried about possible damage to them from the major motor/esc fail. I also have a TM1000 telemetry module and alti/variometer that were in there at the time, these are my major point of concern. The lipo was charged, not puffy and trusted, I try to look after my lipos! Only 2 things initially spring to mind to me to possibly explain. My DX6 TX (less than 1 year old) was repaired some time ago. It was dropped from a low height and broke a gimble and switch. It was repaired and tested by the manufacturers and has not caused any problems since repaired several months ago and has had at least 15 flights. Maybe it malfunctioned, unlikely? The other is the last time I flew the plane over a month ago, I landed it 3 times in long wet field grass. I had to wipe off the moisture from the wings and cockpit. Not good, but I wonder if this could have caused some kind of corrosion and a short? The flight video with one of these landings is posted on the forum as it was my first video recorded flight with a Mobius camera. Edited By Simon Hall 2 on 27/07/2015 18:53:09 Quote Link to comment Share on other sites More sharing options...
Phil Green Posted July 27, 2015 Share Posted July 27, 2015 Hi Simon, had you set your failsafe? A full-power dive suggests the rx was either set up for full throttle on failsafe, or it was actually receiving a full throttle signal during the dive, or another possibility is that very small number of ESCs maintain their last setting on loss of the servo signal, whereas the vast majority cut the throttle on loss of servo signal. Which particular ESC was it? Before unplugging the lipo did you get to see what the LED was doing on the receiver? I'm guessing the fried motor and ESC was caused by stalling the motor on impact whilst the ESC was still trying to run at full throttle. A full throttle dive shouldn't harm the motor or ESC, in fact it gives both a bit of a rest with the reduced current compared to level flight or climbing. Cheers Phil Edited By Phil Green on 27/07/2015 19:05:46 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 27, 2015 Share Posted July 27, 2015 Does your system log the telemetry? If so, you should be able to see whether the link was lost before the dive and impact... Failing that, was it on DSM2 and was anyone else using the same system? There was a very interesting hypothesis posted a few months ago where a scenario of someone turning on their transmitter close to the ground (and I'd add possibly with their body between their transmitter and the flightline plus your body) might get your transmitter's signals blocked. Then, at something like a 1 in 500 chance (I think!), it might select both channels you're using... I had a complete lockout with a friend's DSM2 model a couple of years ago and no explanation was forthcoming despite extensive checks - even by Horizon. Quote Link to comment Share on other sites More sharing options...
FlyinBrian Posted July 27, 2015 Share Posted July 27, 2015 Perhaps the Motor / ESC fried in the sky so no power to the radio. Quote Link to comment Share on other sites More sharing options...
Pete B Posted July 27, 2015 Share Posted July 27, 2015 Certainly worth getting the telemetry data up here in graph form and we can see what happened with Rx volts etc Have you used the telemetry software yet, Simon? Pete Edited By Pete B - Moderator on 27/07/2015 20:22:06 Quote Link to comment Share on other sites More sharing options...
Simon Hall 2 Posted July 27, 2015 Author Share Posted July 27, 2015 The only other difference on this flight was that I was flying very close (right next to) a friend who has a fairly cheap quad rota drone and he was trying to follow me up to altitude. He lost range on me at about 300ft. I may have telemetry data on my DX6, I will look at this. Quote Link to comment Share on other sites More sharing options...
Simon Hall 2 Posted July 27, 2015 Author Share Posted July 27, 2015 Posted by FlyinBrian on 27/07/2015 20:19:43: Perhaps the Motor / ESC fried in the sky so no power to the radio. I did not think the motor/esc failure would stop control of the servos from the tx. I don't know, just guessing as this has never happened to me before.... Quote Link to comment Share on other sites More sharing options...
Dave Hopkin Posted July 27, 2015 Share Posted July 27, 2015 Posted by Simon Hall 2 on 27/07/2015 20:30:03: Posted by FlyinBrian on 27/07/2015 20:19:43: Perhaps the Motor / ESC fried in the sky so no power to the radio. I did not think the motor/esc failure would stop control of the servos from the tx. I don't know, just guessing as this has never happened to me before.... If it dived in on full power its pretty unlikey the esc freid in mid air Quote Link to comment Share on other sites More sharing options...
ben goodfellow 1 Posted July 27, 2015 Share Posted July 27, 2015 the usual l did you not have your fs set . pilot error i see .... em,mm hold on spektrum again ....say no more Quote Link to comment Share on other sites More sharing options...
Simon Chaddock Posted July 27, 2015 Share Posted July 27, 2015 Simon I would have to agree if the power was still on then either It lost radio contact with the fail safe incorrectly set. Or You were indeed 'shot down' by another signal. I have certainly had an otherwise faultless 2.4 plane (using DSM2) suddenly dive uncontrollably into the ground at a busy open day. None of the radio gear was damaged and it has flown faultless many times since although in my 'lone flyer' environment. As and when you get it back together with it suitably restrained (or the prop off) try switching off the Tx with the plane armed and some throttle set. It is very comforting when you find the motor dies at loss of signal! Edited By Simon Chaddock on 27/07/2015 21:20:35 Quote Link to comment Share on other sites More sharing options...
Frank Skilbeck Posted July 27, 2015 Share Posted July 27, 2015 Was it on full power, or just diving steeply, it could have been that the Lipo became disconnected from the ESC, no brake on the prop so it just windmills. I had this happen on a plane of mine, it was a tight installation so I'd been bending the ESC plug to get it into the battery, over time I'd broken wires underneath the heat shrink, eventually there was just enough strands left to behave like a fuse................... If the Tx failed to transmit then the Rx should have gone into failsafe and shut down the motor (assuming the failsafe was set to do this) Quote Link to comment Share on other sites More sharing options...
Pete B Posted July 27, 2015 Share Posted July 27, 2015 You should get a good idea from the telemetry. You'll have Rx volts and the altitude - at the time it started diving does it lose all data? If so, that would indicate a loss of power to the Rx, possibly the BEC frying and you'd lose servo control. I think there's then a possibility that the motor would either cut out within a couple of seconds as it should, or it may carry on runningif it doesn't register the loss of signal..... You've got the equivalent of a simple FDR there, Simon - might as well use it! Pete Edited By Pete B - Moderator on 27/07/2015 21:48:17 Quote Link to comment Share on other sites More sharing options...
Phil Green Posted July 27, 2015 Share Posted July 27, 2015 Posted by Martin Harris on 27/07/2015 19:43:29: There was a very interesting hypothesis posted a few months ago where a scenario of someone turning on their transmitter close to the ground (and I'd add possibly with their body between their transmitter and the flightline plus your body) might get your transmitter's signals blocked. Then, at something like a 1 in 500 chance (I think!), it might select both channels you're using... Yes that was me Martin. However several sets can happily use the very same channels, thats not a problem, this is SS its not like 35mhz channels. The concern in the post you mention was that switching on with the tx laid on the grass gives it no chance of hearing non-rc signals (eg video) and avoiding them. **LINK** Simon, the audio on the camera video file will also confirm if the motor was running or freewheeling. Cheers Phil Edited By Phil Green on 28/07/2015 12:51:59 Quote Link to comment Share on other sites More sharing options...
Martin Harris - Moderator Posted July 27, 2015 Share Posted July 27, 2015 I had a good idea that it was you Phil but I hadn't taken on board that you were referring to sources other than other RC transmitters - I did wonder a little as I thought SS tolerated simultaneous transmission to certain limits of the noise floor - but knowing a little of your pedigree took it as a real concern. It seems good advice to raise DSM2 transmitters well away from the ground for switch on and well worth publicising! Quote Link to comment Share on other sites More sharing options...
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