Hi Guy's I had a crash today with my skywalker. It has never battered an eyelid at anything I have thrown at it and has flown many missions without a hiccup. Today I went for a fly at my usual haunt. I uploaded an auto flight with 4 waypoints (I have flown these waypoints before) and hand launched after waiting approximately 5 minutes for the GPS fix. I flew around for a minute or two whilst I positioned the goggles on my head and when they where on I flicked through stabilise to Auto. Once it went into Auto the engine reved up and the skywalker banked slightly to the left (to get on track) and pitched down violently, I tried to pull up but it did not respond at all, I went to Manual mode and by that time it was too late.
I did notice my airspeed went nuts but it was windy around 6 Knts variable. Also the HUD was not reflecting my pitched down angle, Also Ignore the Voltage on the screen, The Voltage has not been calibrated.
I have attached my .tlog, .log amd kmz file for everyone to look at. I have had a look but I can't decipher the logs. Also attached the FPV video as well as the Wing cam.
Another thing I noticed in the kmz file was showing I was flying in yellow stabilise but in actual fact I was in manual which should have been orange. the green in the middle of the yellow and blue reflects me going through Stabilise green to get to Auto black but the kmz shows me going into RTL which is blue. The OSD reflects me going into manual, taking off, flying then going through stabilise to get to auto, I never hit RTL ?
I hope it was something I have done because it was going so well and this was just unexpected.
Any info would be appreciated.
I will upload the Video's as soon as they get to youtube.
I did see "Batt Low" on the HUD just before the pitch down??
Please check your motor thurst. I think it's important to make correct motor thrust on pusher airplane type. Fly in manual mode then full throttle, and notice if it has tendency nose dive. I have similiar problem with SW1880, it happened when I switched from FWBA to Auto, while motor rev increasing then suddenly my SW nose dive! The problem solve after re-adjusting motor thrust.
I figured Id chime in here as I had the exact same problem on the exact same airframe. I too was flying a skywalker 1900 and had many great flights until one day, when I switched from FBW-A to Auto, and the motor reved up and nose dived into the ground. After that, I was fortunate enough to have Andrew Tridgell, whom has already posted on here, take the time to walk me through my log files. What we found is that there was a massive amount of magnetic interference with the APM board from the ESC. If you pull your logs and look at the "mag_field", this graph should be linear. Mine was jumpy as all get out. My solution was to move some things around in the airplane to create more space between components as well as shielding what I could. Hopefully this isn't your problem, but it is definitely worth checking.
I would say its worth a try replacing your elevator servo. I had an HXT 900 on an aileron that would intermittently fail to full deflection. It caused two crashes with me thinking it was a brownout.
My condolences for the crash ...
Shortly before switching to auto mode, your battery warning signals again, it may be that you had too little power? Greetings from Germany, Klaus
I Adrian. I've just looked at your video and kmz and they do not agree at all re. altutude. Your OSD frequently shows the wrong altitude especially towards the end. I can also see No GPS Lock flashing at least once. I'm thinking it's a GPS issue. I had the same thing, bad GPS lock sent my skywalker into the earth: https://www.youtube.com/watch?v=17GaSx7UbJY
I'll see if I can get time to check the tlog. Can you upload your parameters?
I would like to better understand the APM logs so I decided to take a look at Adrian's. I'm not going to be able to solve this but could someone please tell me the difference between RELALT and ALT.
I have searched the Internet and can't find any reference to the two.
Hi Adrian. I had exactly the same issue with my Bixler. I had a good takeoff in manual, switched to auto once the bird was up. She banked to the first waypoint, climbed out to 200m. Then on route to waypoint 2, did a sharp bank and nosedived from 200m to mother earth. My logs does not show anything about the last bank. It was only half way to waypoint 2.
I'm using an APM2.5 with GPS and telemetry. I've flown this configuration many times with a down facing camera. I was using 2.73 firmware, and like you, I don't fiddle much with settings. I checked the wiring and mounts before launch. All seemed fine. All I can think is that somehow the power in the setup went down. Yeah, so we learn. I'll split the power needs of my servos and APM from now on. Here are my log files as well....if it helps.
2013-07-08 12-51 57.kmz
2013-07-08 12-51 57.log
2013-07-08 12-51 57.log.gpx
I used to have similiar issues with my Skywalker Condor 1880 hard bank and crash. Are you using APM2.5+ with power module and JP1 off. And powering your servos with external BEC and small separate battery instead from the esc?
Somehow for me the problem went away by itself. I don't experience this anymore. Whats different now is that im using APM2.5+ with the power module, JP1 off and my output rails(servos) are powered by external Castle 10A BEC at 6V . We supposed the power module helped a lot since we already was using separate BEC for the output when it was crashing. Also when we bought new APM 2.5+ it had the pink foam covering the baro which may have helped. Honestly now we don't know what really solved it, new hardware or new firmware. It my also be that our APM wasnt properly secured in our plane previously. So many hypothesis. But power module seems to be the more logical reson as previously the input voltage to the APM wasnt clean and constant at 5v and sometimes dropped way below 4.5V.
Whatother steps i take of course is to first balance the plane well, make sure its not too nose heavy or tail heavy. reduce your travel on the control surfaces to prevent stall especially during steep turns. Then i reduce the bank angle in Mission Planner.
So far after a couple of months no crashes. Hope you find out whats the real cause. Even though it doesn't crash on me anymore its kinda unnerving not really knowing the root cause.
Video from the wing cam