I was cruising with my quadcopter and performing some altitude changes, when the quadcopter became unresponsive to throttle input and landed with some damage.
Any idea of the cause? The motors seem to work fine after landing…
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It looks like you boost up to nearly 1000m. Early in the descent you switch to stabilise and the throttle is at minimum for a long time. With the very long fall and throttle at minimum in Stabilise mode the copter eventually disarms. Changing to RTL mode doesnt help because of the disarm.
eventually you raise the throttle but the copter will not arm because of the high throttle.
It’s a known behaviour that Stabilise at minimum throttle for a long time will cause a disarm.
Either use a little bit of throttle in Stabilise mode during long descents or maybe set up acro mode and give that a try.
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The same can happen in acro. For copters that are expected to spend time at very low throttle, using airmode is recommend.
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That log looks strange to me, it was rearmed after disarm and switched to RTL by RC8, motors were commanded MOT_SPIN_ARM all the time till the crash no matter what input RC throttle was. Also it did not allow switching to stabilize from RTL.
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I believe I was applying some throttle before the disarm though.
Guess I’ll have to use airmode then, though would prefer not to have throttle active to speed up the descent.
So this disarming due to “zero” throttle seems to only happen sometimes?
Roman:
I had this happen to me a few years ago with another flight controller. When I moved to Arducopter based FCs, I created a THR curve in the radio. The curve is from -85 to +100. It is invoked on a switch for any flight mode, so it will keep you from accidentally zeroing out the THR. I normally fly around in Loiter, but if I need a rapid descent, switch to Stabilize and drop the THR to (physical) zero and I’m protected with the curve.
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2026-03-11-17-05-43_Analyze_Report.txt (10.5 KB). check this mate
An… interesting report, but doesn’t seem to match reality well, there are no significant vibrations in logs near the time of loss of thrust.
From what I’m seeing the quadcopter somehow determined that it landed… while it was descending at 20m/s or so.
That report is simply AI slop.
Curious what use case requires a near free fall of 1000 meters. Suggest you read through the following link:
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We are towing a “sattelite” and want to use the most efficient way to come down, which seems to be zero throttle descent.
1000m was excessive maybe 
.
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Look for scripted fast descent, suing a spiral