Hello Community,

Fresh to the community. Been using APM 2.5 for about two months and love it!

I built a DJI f450 quad copter with the APM 2.5 installed within a weatherproof contain (cd spindle). See Picture. APM is mounted on a bit of foam tape within the enclosure.

When I first started flying it in stabilize mode I could fly it incredibly aggressively and the APM kept the copter stable, in the air and corrected all my aggressive flying without issue even handling moderate wind like a champ. I was amazed at what APM could do!

Then several flights in with the copter it randomly corkscrewed into the ground. It didnt damage it all that much and I got it back in the air with a few fixes and could not repeat the issues right away. Unfortunately the issue seems to get worst and worst to the point it would randomly either front flip into the ground or corkscrew into the ground with almost no warning or perceived trigger. I am afraid to fly it now. :(

A fellow flyer suggest that the minor damage to the propellers could be inducing vibrations that cause the APM sensors to go haywire and resulting in crashes so I replaced the props and found the most level place in my house to calibrate the leveling of the sensors. I took the copter out and started flying it and it still seemed a bit off with what looks like hiccups in its stability, wondering (not able to hold a position) and while I flew it moderately aggressively I could see it starting to lose it and at one point it did lose total control dropped about 30 feet but recovered seconds from impact.

So though it seems the prop replacement has improved the all out catastrophic loss of control slightly there seems to be something wrong and Im having trouble translating the tlogs myself. Thank goodness for the telemetry data!!!

I have included two tlogs:

Prior to prop replacement  around 17:49:00- Full loss of control and crash - 2012-10-05 17-46-14.tlog

After prop replacement around 21:17:30 - Loss of control at higher altitude and was able to recover - 2012-10-10 21-15-27.tlog

Can someone help me decipher what is going on with APM? Is the APM failing me? Would love to learn where to look but a bit new to the entire system to be able to identify the problem...

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Sounds like you're getting brownouts. Have you tried powering it with a stand-alone BEC?

Hey Chris,

I was wondering if there was some sort of power failure going on either to the APM or the motor. I am running 3S batteries that are 30C.

The APM is powered by a "Castle 10amp max BEC" - www.castlecreations.com/products/ccbec.html

It is defaulted to 5.1v setting but I just connected my multimeter and it is closer to 5.01v.

Like I said before it was flying great for several flights, 10-15 easily with the same setup... and now all of a sudden it seems like the sensors are troubled, confused or failing. The problem started off very random but now it is any time I take off. I fly it only in stabilization mode and if I push to far on the stick in any direction it will trigger the erratic behavior almost every time. Did a front flip, recovered to then corkscrew to crash.

Is there any data I can look at that would help narrow down the failure point?

Ps. Got into the APM game after seeing your presenation at DEFCON20. :)

What version of the code are you using? 

Ive experienced the problem with the 2.7 and as of today after doing a full rebuild of where the APM sits 2.8.

I dont want to follow a red herring but the brown out theory makes sense. I just checked the solders from the distro board to the bec and they seem pretty solid and the output like I said was sitting at 5.01v.

I tried to interpret the tlogs but there are just too many data points to know which ones are important but I imagine there is one data point that shows one of the sensors losing its mind causing the copter to dive...

As well this happens right from take off with fully charged batteries.

Is there any explanation why it was flying great without incident for 10 flights and now all of a sudden cant fly without the instability. Power could be the issue but what would cause it to start failing all of a sudden?

Im willing to test another BEC but its going to take a week or two to get one and get it on my bird to test.

Is there anything in the tlogs I can look at to help me narrow down the problem?

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