mid flight FC fail

[tovrin]

I had an interesting thing happen recently with my flip 1.5

I had just fixed a broken ESC wire and had tested everything before flying, including holding the copter in hand and giving it full throttle to make sure nothing stopped and all my ESCs were working, not getting hot etc.

so i put the bird in the air and get it above the tree line, let it hover and suddenly it just drops, all 4 motors just stop, luckily it fell into a tree and didnt do much damage.

after i fixed it, i tried to replicate the problem, and could not do it. ive carefully put several batteries through it since and it hasnt done it again, but im worried, and havent gotten it real high since just in case it drops again.

anyone have any thoughts? Ive seen and replied to several posts about similar issues, but they all seem to be related to wind or vibration and i cant say that i had either.

my escs dont get hot, my FC is rubber mounted and has minimal vibration on gui, even in air. (I love bluetooth monitoring)

[copterrichie]

I know the situation well, I had something similar happen with Mollie II but have not been able to replicate it. Not sure it is firmware related.

[copterrichie]

P.S. I suspect in my situation, it was/is a PWM cable to the ESCs.

[alll]

All 4 motors at the same time ?..., i had this 1 hour ago!..., repaired the broken motor support, flew 3D without a problem...., mmm, strange.
manu

[subaru4wd]

What transmitter & receiver are you using? I had the same thing happen to me once with my stock Turnigy 9x 2.4ghz module. All motors quit, and my tricopter fell to the ground.

[alll]

FrSky FASST PPM out!

[tovrin]

my TX is a cheap ESKY 2.4ghz 6 channel, nothing fancy at all, but i dont see how it could have caused the copter to shut down, unless im missing something.

[copterrichie]

my TX is a cheap ESKY 2.4ghz 6 channel, nothing fancy at all, but i dont see how it could have caused the copter to shut down, unless im missing something.

The only thing that I can possibly imagine would be, something within the FAILSAFE code is triggered by a glitch in the signal.

[trello]

What kind of FC do you use? I had the same thing happen and switched to a different bec thats rated at 5.3V. Haven't had it happen since then and i've flown quite a few times.

See also here.

[Plüschi]

I did see this "drop out of the air" a couple of times. My 23cm quad on 2S 800mah does this quite often, about every 5th flight. I have also seen this on the F450, but not often. No idea where that comes from. I do use DSM2 on the small one and Frsky PPMSUM on the bigger.

My 10cm brushed DSM2 quad does NEVER do this. It runs on 1S and has an on-board step-up to 5V.
I will now upgrade my 23cm quad to "ext power" and not use the ESC BEC any more.

Edit:

Researching the power supply i did find out most modern boards have a low drop regulator for internal stuff. Instead of the 5.0V from the ESC BEC the CPU then gets 4.9V. Enough. 6V from the raw input will give the full 5.0V to CPU.

Not so my Red MultiWii Pro board from HK. The 5V regulator drops an astonishing 1.1 Volt. There is no "raw" input on this board. The 5.0V from the ESC BEC will give only 3.9V on the cpu. BAD.
This board was discarded because of lots of "hiccups" during flight.

[tovrin]

it happened again today, i had just burned through 2 3S batteries, put my 4S on and was doing some flips, then went to circle around and poof, she just dropped. luckily no harm done, didnt even lose a prop this time. i had just upgraded to dev, from 2.2 and had been flying it in my front yard all day tuning the pids (holy god, dev pids are sensitive, had to turn everything WAY down, in fact im running without D at all, and almost no I)

my board is the flip 1.5 form readytoflyquads.com

[copterrichie]

BEC problem?

[tovrin]

its possible, i am getting power from all 4 ESC's plugged directly into the board. I have always done this and never had an issue before

[copterrichie]

I have read various opinions about having all of the power pins from the ESCs connected at once. Some say it is not a good practice, others claims it does not matter. I personally do not power my copters from the ESC but a separate BEC. Electronics have a way of breaking down or becoming weak over time, I have seen many resistors change value as they age. I also have seem MANY voltage regulators fail with time also.

[Plüschi]

If those are linear bec there is no problem with having them parallel. But switching bec does not like it.

Tovrin, I assume your BEC is 5V. Could you measure the voltage after the regulator on the flip board? Careful ....
I dont know if flip has low drop or normal 5V regulator. A normal drop might cause problems, but im not sure.