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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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

Hi Jason,

thanks for the fast answer!

I knew, that trimming throttle would not be a good idea. Yes... my props are too small... I'll put on the 3 blades to see, if it makes a difference. I always felt, that the motors are spinning too high.

Oh - autocalibrate would be so cool. I highly appreciate your work!!!

Joerg

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.

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!

I'm running a dji f450 with 10x5" graupner props powered by 6000mah 4s lipo. My problem is that hover is somewhere around 35% and anything over 50% is like rocket powered. I've lowered the the Throttle Rate P down from 3.0 to 0.9 and haven't noticed a difference in where the hover position is. Its nearly impossible for me to find the hover position with it being so low. Do you have any ideas? What am I missing?

The middle of the stick doesn't necessarily mean the perfect amount of thrust for hover. If you're having trouble finding the right throttle for hover you could try putting a response curve on the throttle for the radio, reducing the maximum throttle with the Mission Planner, or using a flight mode that maintains the altitude for you (like loiter or altitude hold). If you're fairly new it might just take time to get used to it, the throttle and hovering were the most difficult things for me to learn.

Throttle rate P will not have an effect on this. Use throttle rate P when tuning altitude hold. Try a 3s battery instead, the props will spin slower. It sounds like you don't need a 4S anyway.
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.

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