I had a crash last month and I attached my tlogs. Could someone help me figure out what went wrong? Attached is a tlog:
I had a downward facing mobius taking time lapse photos of a sewage stream running into Lake Titicaca of Peru.
I usually never have any problems but I pushed the limit with this flight and took some short cuts:
I didn't recalibrate the accelerometer or compass upon traveling about 30 miles from the last location. I rushed the preflight check and flew despite seeing that the accelerometer was a little off and the IRIS didn't take off evenly. I also didn't check the GPS fix before I took off, even after noting the clouds and sporadic drizzling. I did wait about 5 minutes but that didn't seem to fix things. The crowd of eager college students watching and the ground elevation of 12,500 feet didn't help things.
The IRIS went up, wouldn't loiter, wouldn't hold altitude, wouldn't RTL and flew away. I thought that it would crash into the lake and I would be out one IRIS.
I realize that was too much of optimism for any pilot but I'm wondering if anyone could look at the tlogs and tell me what exactly went wrong.
The good news and REALLY good luck:
#1 It crashed into a bush near a main road and only broke props and my temporary mobius camera mount. The mobius camera seemed to have rolled away but it was also in perfect condition after the crash.
#2 A man was standing near the IRIS when I ran over to find it. I gave him 2 soles (USD 0.73) for watching it.
Other than this crash, My IRIS has been very reliable and I usually have very good landings.
Replies
At a flying field altitude (ASL) of 3,812 metres (12,507 ft) you don't have enough lift with a stock IRIS to fly safely. You actually need close to 100% throttle at that altitude just to keep hovering in the air.
Look at the throttle from your tlog in the attached file. You're at 100% shortly before the crash.
At that altitude you need to compensate for the thin air: Either fly with larger props - which is not possible on IRIS as we are already at the max with 10" props - or use 4S batteries.
You should use http://www.ecalc.ch/xcoptercalc.php to determine if you can actually fly with a certain config at a certain location. Here is more on that: http://cloud-surfer.net/2014/07/10/3dr-iris-with-gimbal-and-tall-le...
titicaca.png
Thank you for the response. I just reviewed it and agree. I will not be flying the Original Iris back to that altitude.I like the cloud-surfer discussion on this topic. https://www.cloud-surfer.net/2014/10/10/improving-lift-on-iris-with...
I hate to keep point you at different area, but I'd love to see you get the answer you need.
I'd suggest you post in this log analysis forum.
http://ardupilot.com/forum/viewforum.php?f=80
Before you do that, you'll need to get the data flash log from you Pixhawk. You'll need to open up the top of the IRIS and get the card out of the Pixhawk, and transfer it to your computer.
Here's a PDF to show how to open the IRIS
http://3drobotics.com/wp-content/uploads/2014/02/removing-the-shell...
And here a video showing where the SD card is and how to remove it. The microSD card carrier should have been shipped in the white box with your IRIS.
https://www.youtube.com/watch?v=KVdGWtx9uEA
John
Thank you.. I will open and copy the non-truncated log files.
Hi, isn't possible to export log via USB and MP? Tomas
It is possible, but based on this note, it appears that with code previous to the 3.2 Beta, the process can leave the logs truncated, thus the suggestion to pull them directly from the card.
http://ardupilot.com/forum/viewtopic.php?f=80&t=6614&sid=ce...
Ok, thanks.
Wow!, Sorry about the bad luck man! I did not even know you had to recalibrate anything. Looks like I need to do more research.