Copter does not hold altitude on 50% throttle

Hi there,the follwing problem occures with my little DJI 450, APM2 (2.8.1) quad:I have my throttle spring loaded, when I let go of my throttle stick it is on 50% - but the copter does not even nearly hover - it sinks to the ground pretty fast. I tried to compensate it with the trimming which works but when I land the copter the motors keep spinning and I can't disarm because of my 0% trottle still beeing too high.Can I fix the problem with some PID tuning?Thanks!Joerg

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  • T3
    Your throttle is spring loaded? So if you let go the props will spin if armed? I would not recommend this, in my opinion its an accident waiting to happen. Additionally it makes holding a stick position very difficult, which would make hovering difficult. Its not a huge deal if you don't hover dead in the middle, but you need to be close. Take Jason's advice on upping the battery cell count and reducing weight.
  • Flew my 3DR quad for the first time un-tethered today and experienced a "slightly" similar occurrence.  I will preface this by saying that I did have a Curve on the throttle to keep things in control but I noticed that if I started to descend (lower the throttle) the quad had a tendency to slowly float to the ground.  IE I couldn't give it enough power to keep it in the air.  

    I'm not sure what my total weight is but I'm running a Turnigy 4000mah 30-40c battery on the stock 3DR quad frame with the 850k motors and 10x47 props.  My throttle curve was -100, -15,0,23,100.  

    She handled really smooth around the hover point setup like this, in Stabilize mode she pretty much just hung in the air without my touching the controls. But if I lowered the throttle she landed and I couldn't pull her back up.

    I'm going to drop the curve and re-calibrate everything hopefully get another flight in tomorrow if the weather holds.

    Just thought I'd share my experience.

    Cheers!

  • There's nothing magical about 50% throttle. It might take 20% or 80% or anywhere in between to hover depending on how powerful the copter is. If you want to share the specifics of your configuration it will help to troubleshoot, like the motors, props, battery, weight, etc.

  • Developer

    First, never trim your throttle. You'll need to restore it to normal position and re-calibrate your radio.

    Next try and lighten your quad or use bigger props or higher voltage batteries. 

    We'll have an auto-calibrating throttle soon, but that is masking the real problem. Your quad is probably not propped or powered correctly. Do you have a watt meter? That can help to see your power draw as well.

    Jason

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