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First crash. Telemetry help?

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Doesn't seem to have done much except pop a couple of the mounting pins out of the camera mount.

I was testing CCC mode by flying around a soccer field. I had it orbit the soccer field by setting 3 points at each end of the field. After it crossed the last orbit point, which was midway between the goal post and the corner, I had it move to the center of the field, then point the camera down and climb straight up for a full-field overhead shot as its final waypoint. Then I manually brought it back near the first point. I did not have it change altitude during the orbit or the transition to the center.

Once I put it into autonomous CCC mode, it did what it was supposed to do for the orbit, but as soon as it passed the final orbit point and started transitioning to the center, it rapidly lost altitude and crashed. That's annoying.

I'm no expert at interpreting the telemetry but I don't see any indications of problems at the point it begins its dive. It was locked on to 19 satellites. I got no warnings on the transmitter until after the crash and the motor shut down.

The relevant flying begins at 15:28 with the CCC waypoint setting flight. Automated CCC flight begins at 15:32, and the uncommanded descent begins at 15:34. Any ideas as to what caused this and how to prevent it from happening in the future are appreciated!
 

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  • FlightLog20190409.zip
    12.1 MB · Views: 20
So far this is what I see;
At 15:34:09 ____ Motor status 239; Motor 5 off.
At 15:34:10 ____ Emergency motor shut off
 
I will take a look in the AM.
 
At 10:02
You're having voltage issues.
Disregard this post # I had keyboard issues.
 
Last edited:
@DoomMeister much appreciated!

At 10:02
You're having voltage issues.

Where, exactly? The telemetry file for this flight starts at 15:11:58:059 and ends at 15:35:01:435. I'm not sure what you mean by 10:02.

Where the voltage suddenly goes from 15 to 16.7 is where I changed batteries.
 
Sorry for the delay my keyboard went haywire, so bare with me
 
Hmm. Thanks for looking at this with me. I suspect the green represents CCC mode, as the green bits correspond to when it was in that mode. Looking at the raw, the f_mode is listed as 26, which is CCC mode. I didn't use smart mode during the CCC testing.

I do see the compass calibration error, but it's short and I know I read somewhere that short compass errors aren't a big deal and can be caused by things like the landing gear cycling. Of course, I don't know how accurate that is.

That said, wouldn't it be strange if the compass calibration caused the crash, since it happened a long time (relatively speaking) before it started to descend?
 
I don't see any anomalies in flight no 23. There are two flights in the same log file. I'm curious about the last waypoint. Can you recheck it to see if it was set to 8 meters as the others were?
 
Not directly because I didn't save the CCC list like I should have.

However, if you look at the pre-CCC-mode waypoint-setting lap starting at 15:28, when I fly it over to the center of the field to create waypoint 7 starting at 15:30, I'm still at the 8m mark, and it never descends before getting to the middle of the field and going straight up to create waypoint 8.

So I would think that if waypoint 7 did get set at 0m, it couldn't have been due to the actual location when waypoint 7 got saved.

The *last* waypoint was the one at 83m above that center point, so even if I somehow missed setting the 8m point, it should have just climbed to 83m between waypoints 7 and 8, right?

Actually wait a second. Could it have been flying a Bezier curve in the vertical profile as well as horizontal? Trying to dip below waypoint 7's altitude to smooth the curve upward at waypoint 8?
 
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Could it have been flying a Bezier curve in the vertical profile as well as horizontal? Trying to dip below waypoint 7's altitude to smooth the curve upward at waypoint 8?
Very good question. I don't know the answer but I would not think so. @Ty Pilot might be able to answer that.
 
@Eslader

I took a look at your telemetry file and I really don’t see anything that would cause the crash other than your statement about the Bézier curve causing the crash. That is the only thing that would make any sense at this point.

Too bad you didn’t save the CCC. The one question that remains for me is whether the aircraft was on its way to waypoint 7 or waypoint 8 when it crashed. If it was approaching waypoint 7 then it should have stayed at the same altitude or been climbing some to make a smooth curve for going to waypoint 8.
 
It was on its way to waypoint 7. It started the descent as soon as it passed waypoint 6.

The Bezier curve idea is the only thing I can think of that would have caused it. I'll do some testing with it the next chance the weather gives me, at much higher altitudes, to see if it dips when going from level to a long vertical ascent.
 
I believe the curvature between points happens in both axis's so yeah maybe it extended down ward beyond that lowest point. I am also wondering if having the previous point in exactly the same spot only higher didn't contribute somehow. One thing I have sort of built into my mind when running a CCC is upon the first run have a finger over the exit or pause button just in case.
 
I’m taking a look at the Remote file to see if I find anything in it that may give a clue. I’ll get back with you later.

There is nothing in the Remote file to cause the crash. The final CCC flight started about 15:32:00 and there were no inputs on the ST-16 from just before that time until after the crash when the landing gear switch was placed in lower the gear position.

The one thing I see is after the turn at position 6 it appears the aircraft was heading for midfield and not to position 7. This is by looking straight down on the flightpath using the kml file in Google Earth Pro.

RC_throttle-altitude-f_mode.png
throttle - descend < neutral (2048) < ascend
altitude - meters
f_mode - 3 (Angle), 26 (CCC), 16 (on ground motors not armed)

RC_roll-RC_pitch-RC_yaw.png
RC_roll - left < neutral (2048) < right
RC_pitch - back < neutral (2048) < forward
RC_yaw - left < neutral (2048) < right

AC_roll-AC_pitch-AC_yaw.png
AC_roll - left (+ values), right (- values)
AC_pitch - back (+ values), forward (- values)
AC_yaw - left (decreasing heading values), right (increasing heading values)

Tilt_mode-Tilt_slider-Pan_knob.png
Tilt_mode - 3412 (velocity mode) position 3 full down
Tilt_slider - 0 deg level (683), -90 deg full down (3413)
Pan_knob - rotate left < neutral (2048) < rotate right

For the kml file remove the .txt extension then load in Google Earth to view.
 

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  • Telemetry00023.kml.txt
    2.6 MB · Views: 2
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That's very valuable information. Yes, it should have been heading to the center of the field after rounding the last corner. The KML file makes it look like it straightened out and was heading for the opposite end, but that's not what I recall seeing in person - it was, from my perspective, curving toward its run to the center.

I hit the gear switch miliseconds before it crashed, foolishly hoping I could get it down in time to shield the camera since at the time I thought it was completely out of control. I should have hit the stop button or the mode switch. Bad piloting on my part.

With all the input I've received here I'm heavily leaning toward it curving itself into the ground to round out the vertical turn for the center-field climb. The weather is going to keep me grounded for the next few days but as soon as I get a chance I'll hover-test it to be sure it's still airworthy, and then I'll do some steep vertical CCC work at higher altitudes to see if it dips down in a similar waypoint setup.

I really appreciate everyone's input. Thanks very much!
 
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Sounds like a good plan.

So point 7 was the last corner before going into the climb at center field? If that is the case then it was heading that direction. After the last corner it was starting to curve for the middle, but also curving down. It is easier to see it looking straight down on the path.

Placing more points at progressively higher altitudes along your own curve may lessen the tendency to dip before a steep climb.
 
The point I've been referring to as point 7 was in the center of the field at 8m. Point 8 was in the same place, but much higher. Point 6 was roughly at the northwest corner of the field.

Not thinking the "cable" would dip below the ground, my plan was to fly from 6 to 7 at 8 meters, then shoot straight up as the camera tilted down. That's apparently a bad idea. ;)
 
The point I've been referring to as point 7 was in the center of the field at 8m. Point 8 was in the same place, but much higher. Point 6 was roughly at the northwest corner of the field.

Not thinking the "cable" would dip below the ground, my plan was to fly from 6 to 7 at 8 meters, then shoot straight up as the camera tilted down. That's apparently a bad idea. ;)
Hard way to learn sometimes, isn't it? ?
 
Heh. Definitely. Fortunately there doesn't seem to be any damage, but I'm a little dismayed that I failed to understand CCC vertical profiles sufficiently before messing with it (if in fact that's what it was).
 
When you retry the setup I would try it from about 60 feet up to give yourself time to react. Your accident brought up a very good point to be aware of when using a CCC and transitioning to a vertical climb. I am very interested in your results, as I'm sure many others are.
 
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