XAircraft Black Box Data Analysis

Racerx1962

Racerx1962

Member
Here are 2 flights with different copters using 2 separate SXs... Both flown on 12/15/14. The first was a test flight of my 800mm quad; it was the maiden flight... After a few seconds into the flight, the quad just flipped and crashed. Fortunately, the damage was limited to a broken GPS mast and one prop. Here's the link: http://log.xaircraft.com/#2014_12_17_104315.250_16.2.00.17

From the data, the voltage drops significantly; but I don't know if it's a cause or a symptom of the crash.

The second flight was with my DYS D800 quad... After flying for a few minutes, the quad almost did the same thing; that is, it dipped on one side, but it quickly recovered. I landed it shortly thereafter fearing another anomaly. Here is that link: http://log.xaircraft.com/#2014_12_17_105227.000_21.1.04.26

I had flown the DYS on several other occasions with no issues whatsoever. It was flawless.

I would appreciate any input from my fellow SX experts.

Thanks

Tom
 

mediaguru

mediaguru

Member
The logging feature is SO useful.

Log ending in .17 I see a couple of key points in time. 16:53 starts a big drop in voltage and the nose dives. Motor 1 hits 99%. I'd guess the big drop in voltage is because of the jump in motor power. But why? The most bizarre thing to me is your average motor power levels are all in the mid 20's. If I was in the mid 20's my bird would fall from the sky. My non-professional guess on this one is that your motor power was so low that maybe they shut off for a second and it started to fall. The SX then says "oh sh*t" and hits the gas to compensate, but sends too much power to one side, causing the flip.

What % does that bird hover at? It should be 50%.

The second one looks eerily like an issue I've had. At 240 the log says you switched from GPS to manual mode for a second, enough to cause your glitch. Whether you actually did switch is unknown, you didn't mention that. I've had two such instances where the bird dropped and corrected itself and the log said I switched to manual for a second.
 

mediaguru

mediaguru

Member
...and you can see your log ending in .26 shows a better range for your motor percentages, around 50%.

What TX are you using? Taranis perhaps? I saw the G knob on your first log was at -15 and the second was at +15.
 

Racerx1962

Racerx1962

Member
The setup might be the reason for the first case... it's a 800mm quad with huge Dualsky 7010s, HW 70 A ESCs and 20 inch props with NO load. When she lifted off the ground, the copter was rocketing off a bit faster than I wanted, that's why the throttle was so low. I'm pretty sure I never zeroed it out, but it could have happened. For the next test, I'll strap on a 5lb weight.

As for the second, I saw the GPS blip, as well. While anything is possible, I'm certain that I didn't accidentally flip the switch. Could it have been some type of EMI? Perhaps there was increased solar activity?

And, yes, I'm using the Taranis.
 


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