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 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 hiccums 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...


2012-10-05 17-46-14.tlog

2012-10-10 21-15-27.tlog

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  • Not being an expert log analyser myself, I can't help from that side. 

    However, from the symptoms, it sounds like you might be intermittently losing a motor.  Front flip suggests it's perhaps the front motor.  One of the common causes of this is a bad bullet connector, particularly common with the ones that swivel.  If you are using bullet connectors, I'd suggest soldering them all together permanently.  Otherwise, check your ESC to APM connections.

    It may also be a bad motor or ESC.

    Another thought is an ESC shutdown due to low battery voltage.  Are you running a battery monitor?  What ESC settings are you running?

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