Unexplainable NAZA GPS Wreck - Quad fell from the sky but not like a brick

[acbruno]

I have a Next Level 650 quad with the DJI Naza and GPS installed and functioning very well. I was out at the field performing a FPV flight last Friday when the incident occurred. Winds were calm with some small gusts. It was my first flight of the day. I took off and switched to GPS mode and started flying around. About a minute into the flight, the quad started to move violently back and forth left to right. I tried to correct it a few times but it didn’t make a difference then I lost video and it crashed to the ground but stayed upright. I looked at my gopro camera and it was flashing FULL on the LCD screen. I thought this was odd since the 16gb card was empty before I took off. Later I downloaded the video and the video cuts out before the violent left to right oscillations occurred. There was plenty of storage left on the card and the camera appears to be functioning fine. I have had many good flights with the current configuration and software settings. Current autopilot gains were set at 135% from the factory and that’s what I left them at.

Update, this happened again last night, no wind at all, it just fell from the sky oscillating all the way to the ground with motors still running. It hit the ground hard enough to break the landing gear but not hard enough to break anything else. The SD card was ejected upon impact. The video recorded up to right before the point the oscillations occurred. I can’t trust this DJI Naza system anymore until I figure out the problem. I might try turning off the battery monitor mode and see if I can get it to happen again.

Any thoughts?

 

[Tahoe Ed]

The GoPro cameras are a known source of interference. I would start by removing or turning off your camera and your FPV equipment. Does it do it then? No, add one system back in and test again. Continue until you find the problem.

 

[kloner]

is the gps mapped out right in assistant. - and + are right?

 

[acbruno]

The GPS should be mapped fine but I will check that tonight.

 

[mailman35]

i have stopped using my gps all together, when flying with it it led to more unknowns that just wherent there w/o it.

 

[acbruno]

I'll post a pic of my setup tonight. I'm using a inverted V antennae and I have it taped to one of the arms with the open Y part facing the motor on the arm. Transmitter is 900mhz and 500mw power. Not sure if that causes any problems there. I'll take out the transmiiter and camera and see if I can get this narrowed down.

I had the camera output on 1.3mhz but when I spooled up the motors, I lost all video so I switched to 900mhz and all is good.

 

[acbruno]

View attachment 5508I had two flights tonight with default gains, one with vide transmitter on and another with it off. I do more testing with the go pro when I get the mount fixed. I also noticed one of the arms was bent up a little. I bent it back and will try it out for the next flight. Thanks to Kloner, I checked my GPS offsets and I did have two of them positive when they should have been negative. I will report back later.

 

[flightrobotix]

Just an idea.....

I have heared about two naza incidents during the last G1 storm:

http://www.multirotorforums.com/showthread.php?5063-Geomagnetig-Field-disturbances-expected

Frank

 

[Dewster]

The GoPro cameras are a known source of interference. I would start by removing or turning off your camera and your FPV equipment. Does it do it then? No, add one system back in and test again. Continue until you find the problem.

I never heard of a Gopro causing interferrence. I fly with my WKM and have the Gopro attached to the underside of my F450. I would look at the positioning of the antennas, especially FPV video transmitters. I keep my receiver opposite (as far as I can) away from the video transmitter.

 

[Dewster]

Unexplainable drops are the biggest fear. A somewhat controlled descent if definitely preferred.

 

[acbruno]

It was somewhat controlled but wobbly and hit the ground hard enough to break the landing gear and camera mount.

 

[acbruno]

It did it again last Friday. About 2 minutes into a FPV flight on my way back and it started to wobble/toilet bowl all of a sudden and decended. I switched from GPS to attitude to manual and hit the throttle but got nothing and no video on my GOPRO as well. I found it in a bean field upside down with the GPS module broke off the mount and three props busted along with the GOPRO mount.

I remounted the GPS and installed new props and it is flying fine now until the next unexplained incident. Could it be my 900ghz transmitter causing issues, the GOPRO, or something with the DJI?

I have flown without the video transmitter, without the GOPRO, and variations of each with low gains of 100% and cannot get it to fail. Before this last wreck, I had 15 good similar flights without incident. Any ideas what to try next?

 

[kloner]

I htink i have seen filters for the 900 to prevent them from interfering with 2.4/ it would be brand specific,,,, got any pictures of the layout?

 

[kloner]

yes it is available, read the whole description too about other sources of interference as well

http://www.readymaderc.com/store/index.php?main_page=product_info&cPath=11_45_58&products_id=493

 

[acbruno]

View attachment 6111View attachment 6112View attachment 6113

Here is my setup. I do lose total control of the craft when this happens but I would think the failsafe would kick in. I have tested failsafe many times and it works great. I ordered the 900mhz filter. Thanks for the link.

 

[kloner]

where is the ar8000 sat antenna?

 

[acbruno]

where is the ar8000 sat antenna?

The sat receiver is taped to the right rear arm. Look for the yellow fuel tube used to keep the antennae wire straight.

 

[kloner]

you got 10 lbs in a 5 lbs bag

i'm gonna make a short list of things i see wrong and we can go over em one at a time if you need more

the ar8000 is nestled in a grip of rx to naza wires = bad that antenna should be out in the clear and not near a wire for lets call 2-3cm for now since there touching as is

the inverted v would help if you can put it forward the arm, i know, doesn't seem like much but ever mm makes a difference

the sat is ok, i'd rather see it on teh front arm just to get away from all that wire and deans plugs,,,,,, not soldered properly makes em noisy. soldering them properly means solderd with a male and female plugged together than to let cool left plugged in. anything else doesnt work. easy way to tell is it should be easy to plug in and out

vu is really close to the gps, does it ever take a while to lock in and flash green?

those esc wires would love to be twisted like the red, orange and brown naza wires, all em actualy. the esc wires would be happier kept under the top plate and poke up at the last minute towards the front. will help keep em seperated from flopping where ever. some of em are there, but two are hanging out the side. carefullt split the three colored wires and roll em in your fingers. don';t force the twist, you can break the wire. what it does is makes a bunch of linear polarized wires like your inverted v and the ar8000 antennas into a not linear state by being crooked as hell

i gotta run a couple kids to school, but i'll be back with any questions and i'll look it over more. one thing i can't say enough is seperation, seperation, and seperation

 

[kloner]

one thing that i keep running through my head is how your using linear polarity antennas on everything. since there is a known problem with the video transmitter screwing with the rc rx, this would extremely benefit from circular polarized antennas, problem being the real estate were working with. it's too bad the antennas are 7" across, the problem with 900

With all that said i got an idea....... do you have the origional rubber antenna that came with your gear?

When a linear antenna isnt the same exact angle on rx as tx, they loose signal, get static. if your rc system was all 90 degrees and 0 degrees, a rubber duck at 45 degrees would help shift that frequency from hammering the rx signal so bad. problem is when you move forward and tilt, your gonna shift the video signal quality for the worst, but at least it's something to try thatn watch it fall over and over. I've only seen inverted v on planes, usually big ones that got lots of room for .... wait for it.... seperation

When you do get your filter, move some stuff around, versus going outside and flying it, read your radio manual how to turn down the 2.4 signal and check it all on the ground. I usually put the craft in manual so nothing flashes, then walk till i see the vu flash. way cheaper and wiser way to see if it works or sucks

 

[acbruno]

Thanks for the detailed response. I can put the rubber antenna on the 900mhz video transmitter and see if that helps. I'll have to look at my DX-8 manual to see how I limit the range for a test. I think it would force the NAZA into failsafe. I have tested the failsafe function and it works great.