NAZA / GPS FAIL VIDEO, with two flips and full recover! - RC Groups
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Feb 04, 2013, 04:48 PM
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NAZA / GPS FAIL VIDEO, with two flips and full recover!

PLEASE take a moment to watch this video, and help me try and understand why this happened.


HT-FPV Frame
MT2216-12 Motors
Graupner 9x5 props (balanced)
Naza w/GPS
4S power (Thunder Power 3300MAh)
ESC are "whitspy / "Rapid Fire" from Paul Baxter - Flashed with SimonK


Basic - 120 all (Now this is a new setting, and the only thing I have changed about 10 flights ago. It was 140,140,130,130 stock)

ATTI - 100 all (It was 140, 140 stock before I changed it, but I wanted a smoother feel)

SO.. I have no idea what happened, or how high I was and I am hoping some of you with more flying experience can help tell me what you think happened. It was scary, and if I was 10 feet lower in the sky it would have smashed right into a house. So, I am pretty shaken up by this.. and am now trying to trouble shoot as I am flat out scared to fly it again.

Conditions are about 70F in Miami, FL. This was the 4th flight back to back of 7min each flight. This happened 2:14 into the flight. (normally I fly 7min, and the pack tested 15.21V on the ground after landing) (I have cropped the video to show the accident in mid air)

I was flying in ATTI mode.. and I can't remember if the quad flipped over when I hit GPS mode stitch.. or if I was in ATTI the whole time. I know either during the flip or right after I flipped GPS mode for "safety" .. as I landed in GPS mode after the flips.

My mind wonders as to what happened.. and hopefully the video has some clues. I am pretty upset and startled.. and also very blessed I did not cause damage to that house, or worse.

Please reply with your thoughts as to the cause. I cant fly this anymore until I have a better understanding as to the why.

Flips are at 00:41

NAZA FLIP 20130204 (1 min 51 sec)

Thanks so much! BTW, I have about 60 flights @ 7min each since new with no issues like this. I received my quad a month ago.. and is running the latest 1.8 Naza Assist program.

Last edited by Tharr62; Feb 04, 2013 at 04:49 PM. Reason: video link
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Feb 04, 2013, 04:59 PM
Knowledge prevents flyaways
ecks's Avatar
Nice save!
Feb 04, 2013, 05:22 PM
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Were you flying and the quad just flipped or did you hit a switch and the quad flipped?
If you hit a switch then maybe you went into manual mode which caused it to flip. Going back to GPS mode would re-stabilize the quad.
Feb 04, 2013, 05:39 PM
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Good thought, but no. Manual mode is actually disabled in my tx. I have moved my end point so that the Naza only sees atti and GPS. When I calibrate gps I move it back.

I think I was in atti mode and then I either flipped to GPS and it happened OR it just happened in atti and then I flipped to GPS on the way down. It happened so fast and was unexpected.

Are there any clues in the video perhaps?
Feb 04, 2013, 07:03 PM
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Feb 04, 2013, 07:06 PM
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Kenpilot's Avatar


Just a thought, were you ready to descend at that point, and perhaps did you decrease the throttle too far, causing it to go into throttle shutdown?

I have a F450 with Naza M with many flights, but I'm by far an expert on all things Naza. That's my best guess...

You seem to have lost quite a bit of altitude in a very short period of time - AKA the glide ratio of a rock. To be expected I guess.

BTW, is that Ft. Lauderdale or Miami? ;-)
Feb 04, 2013, 08:09 PM
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Hi Ken. No, I dont think I was at all. In fact, I have also programmed a toggle switch on my radio that changes the throtto curve so that after I "arm" the motors I flip the switch and it out puts +25 as a minimum value at dead stick. This way, it's impossible for the motors to "see" 10 or lower value while in flight. After I land, I flip the switch to return to 0.

That is North Miami in the video.
Feb 04, 2013, 09:04 PM
Registered User
Any other thoughts?

Some additional ideas that also came my way from the builder was, it could have been a "brown out" from the rx? Now, I am using a JR 9503 radio (2.4) and a R921X rx with one satellite rx connected. This rx supports "smart fail safe" and I have tested this in the Naza software, and in the field by turning off the tx during flight, and the RTH function of the Naza has been great.

SO, at first when I was told maybe it lost signal for a second, and thats why it dropped.. I was thinking yeah, even so then it should have just gone to fail safe? and in which case the system would have brought it back to home. He challenged that perhaps it was a "brown out" ??? and that sometimes it wont trigger "failsafe"?

Thoughts on this / additional ideas?

I asked him about the ESC? What if one of them failed for a moment? Would that have done the same thing?

This is driving me nuts.
Feb 04, 2013, 11:28 PM
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Feb 05, 2013, 12:44 AM
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looks like the front right esc took a dive. for a second. Sounds like it too.
Feb 05, 2013, 01:02 AM
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looks to me like your esc fail you for that moment, have u check the connections...
Feb 05, 2013, 07:03 AM
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The ESC connections are direct soldered to Motor. No bullets.

Let me ask, if one ESC failed then why did it sound like all of them turned off?
Feb 05, 2013, 10:22 AM
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Feb 05, 2013, 11:27 AM
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Yes all the motors seem to suffer at that time. I would then suspect of the battery but it's hard to tell without taking the risk of flying it again.,..
Feb 05, 2013, 12:39 PM
Since 1902. Maybe.
Olivier_C's Avatar
My own guess (revised after watching in my video editor, CSI Miami ! ) :

A brief cut on 1 motor (front right), then the Naza throttle down the 3 other in a desperate attempt to stay level...
Not a cut on all 4 motors, on the sound track there's always motor(s) still up and running.
... it flips, falls like a brick, and we can hear the props turning reverse (0:45) from the air flow,
Then the controller re-stabilize the whole thing pretty quick.
Last edited by Olivier_C; Feb 05, 2013 at 01:28 PM.

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