Stumped and Frustrated - My Naza v2 Based TBS Discovery

[FreeAgent]

Hey Guys, I'm normally more of a reader than a poster, but I am at a loss for a solution to a problem that has caused 2 crashes in the last 2 times I've gone flying.

Here is what happened:

1 week ago I was out flying my naza v2 based quad, FPV'ing through goggles. I flew one pack and it flew great, like I've done many many times before. I put in a second pack and begin flying in ATTI mode going pretty fast making passes past where I was standing. With full forward stick, I start to turn around so I let off the stick and nothing happens, it keeps going full forward. Normally when it doesnt respond it is because it kicked into failsafe mode because I am out of range or behind an object. This time it did NOT go into failsafe, I simply did not have control, it kept going forward on its same path, I tried switching between ATTI and GPS ATTI with no response (didnt try manual this time). It eventually slowed down and I watched in my goggles as it crash landed into some bushes. I tried to disarm the motors but they kept spinning for a good 30 seconds or so and eventually stopped. When I get to it weeds were wrapped around one motor. I took it home and smelled the motor and it was burnt out. I ordered another motor, replaced it, tested it on my work bench, everything seemed to be good to go again.

Fast forward to today: I went out flying, not doing FPV this time, got a good 5 minutes of normal flying, everything going great. Making another slow pass past me and slowing down in ATTI mode. I notice that its no longer responding to my controls again, just hovering and slowly drifting. I was about 20 feet away from me and 40 feet up, no obstructions. I switch to GPS mode and still no control, then I switch to manual mode and it instantly tumbles to the ground hard. I dont want to talk about the damage it received! (Also, I DO know how to fly manual and do it on this setup a fair amount)

I'm at a point now where I dont know where to start diagnosing this problem, at this point as I see it there are 3 potential components to blame; ESC's, NAZA v2, or my radio/reciever.

This is my second quad I have built and have been flying for 3 or 4 years, any help would be greatly appreciated!

Here is my setup in question:

Copter:
NAZA v2 w/GPS
DJI 2212 920kv motors (the red ones)
DJI 10 x 3.8 props
DJI 30 amp esc's
TBS Discovery Frame

FPV Gear:
DJI 5.8 Receiver and transmitter
Security camera for FPV
DJI iOSD mini
Fatshark Base Goggles

Radio:
Futaba T8J and R2008SB Receiver

 

[econfly]

I switch to GPS mode and still no control, then I switch to manual mode and it instantly tumbles to the ground hard. I dont want to talk about the damage it received! (Also, I DO know how to fly manual and do it on this setup a fair amount)

Could it be a battery issue? Where was the throttle when you switched to manual? The instant tumble to the ground when you switched to manual is a important clue as to what is going on, I think. It tells you the receiver was working, the radio was working, the NAZA was getting the signal to switch to manual, so likely was getting other radio inputs as well. So what was failing? It's also interesting that things work for a while then stop. That sounds like a power or heat issue as well. My guess is battery voltage is sagging, weight to power is too high, or ESCs or motors are getting too hot.

 

[FreeAgent]

I dont believe its a battery issue since I used 2 different batteries each time I flew. The throttle was roughly at half when I switched to manual mode. Your right, It is interesting that things work well for a while and then stop working. Ive felt the esc's and they dont seem to be very warm. Im stumped thats for sure.

 

[chipwich]

3S or 4S?

 

[PeteDee]

What throttle position do you use to hover in manual mode, if it is not 50& then switching from atti to manual is going to be problematic?

Which version of firmware?

Pete

 

[FreeAgent]

I use 3s 5000mah packs. Also, it hovers at roughly 50% throttle in manual mode, so I think that should be ok, I've switched back and fourth between manual and other modes many times in the past on this same setup. I'm running firmware 4.0 on the main naza v2 unit.

 

[TheUFGadget]

Hi there Free Agent!

Sorry to hear about your issue as nothing is more frustrating than an un-diagnosed problem with a proven aircraft. Honestly to me it sounds like a control link issue, maybe due to passing right over yourself in the deadzone of your antennae. It seems as if the craft lost control link and when it was in atti it maintained the course (with altitude hold) and that's why you could not switch to GPS. That may explain why when you switched to manual it dropped out of the sky...no atti hold at that point. Now the real question is why wasn't it throwing it into failsafe...and you can do a few tests on the computer.

Hook up the NAZA to the comp (props off of course, but I am sure you know that) and:
1. Put in atti mode and turn your transmitter off. See if it is going to the correct failsafe
2. Then do the same with Manual mode
3. Lastly put in atti mode, turn off transmitter, then power on in manual mode and watch your stick inputs.

Let us know what you find and we can go from there! I hope this helps!

 

[FreeAgent]

Thanks for the thoughts TheUFGadget,

I think your right about it losing control link. I went ahead and ordered another futaba reciever to put in. The crash caused both antennae wires to be ripped out, so I'm hoping that will fix it. I did do your test with the quad hooked up to my computer. Everything worked as it should, it went into fail safe every time. I'm am stumped as to why it didnt throw it into fail safe. I'm almost starting to wonder if the location I was flying at has some sort of signal on a close frequency to 2.4 GHZ, although it just doesnt make sense because I was pretty much in the middle of a field!

 

[TheUFGadget]

Thanks for the thoughts TheUFGadget,

I think your right about it losing control link. I went ahead and ordered another futaba reciever to put in. The crash caused both antennae wires to be ripped out, so I'm hoping that will fix it. I did do your test with the quad hooked up to my computer. Everything worked as it should, it went into fail safe every time. I'm am stumped as to why it didnt throw it into fail safe. I'm almost starting to wonder if the location I was flying at has some sort of signal on a close frequency to 2.4 GHZ, although it just doesnt make sense because I was pretty much in the middle of a field!

Hi Free Agent!

Dang I was hoping something would come of that test... My only other thought at it being the control would be that maybe instead of losing control it "glitched" with interference or acted like it was at the end of the range. If that were to hold true that still would not explain why when you either "lost control link" completely it didn't go into failsafe or why you didn't regain it... Let us know what the new receiver does!