Hi !
I browsed through the available parameters for ALT Hold but i cannot find ( or at least i am veeery unsure about some ) parameters to change the climb / descent speed in Alt Hold mode.
Could you help me out on this, i am sue it must be easy but i cannot find it.
Greetings,
Ender
In ALTH you determine the climb- or descent speed with your throttle stick.
[color=#00bc00]Please read the documentation before posting support requests![/color]
Hi Stefan !
Be assured i tried to find out about my problem prior to asking.
I know the way the throttle stick works in Alt Hold mode, what i do not know (well i suspect but i am afraid to try) is how to change the strength of climb / descent in Alt Hold mode.
If i was misunderstood i try to put it even simpler:
How to ascend/descend quicker in Alt Hold with the same Throttle value ?
Greetings,
Ender
Hi,
Just a quick thought,
You can adjust the dead-band center point with the THR-MID parameter, but I dont think you can adjust altitude hold manual response rate in the APM/Pixhawk.
But you likely can by adjusting expo on your throttle on your RC transmitter.
If you are currently using throttle expo on your transmitter that has the effect of increasing the dead-band and decreasing initial altitude change response outside of it.
On most transmitters you can actually put in reverse expo and get it to load more of the rate of change to the center of the throttle area.
This will cause the dead-band to be smaller and the rate of altitude change to be quicker - sooner.
Of course it will change throttle response for all other modes as well so use this method conservatively. 
Best Regards,
Gary
I just quickly tried changing THR_ALT_P and it works. Not sure about side effects yet, though. The OP reminded me that I wanted to fiddle with that also already for a while.
Only works within some limits… I’ll do more experiments tomorrow in daylight - if the weather is ok.
Hi Stefan and ender,
Yes you can adjust both THR_ALT and THR_RATE parameters, but adjustments to either of them are primarily to permit you to affect the altitude hold automatic responsiveness and they simply coincidentally also affect the manual override throttle rate.
Basically if the auto throttle rate is too low, (sluggish) you can increase the rate and it will also increase the manual response rate.
But primarily you really just want to have these values tuned to do the best possible job of automatically maintaining your current altitude without regard to altitude hold manual override rate response.
And preferably fix any manual override discrepancies by other means.
Ideally, adding a manual override rate parameter and a dead-band size parameter could provide a more universal solution at an infinitesimal 
cost in firmware CPU cycles or memory space.
Best Regards,
Gary
[quote=“gary”]Hi Stefan and ender,
Yes you can adjust both THR_ALT and THR_RATE parameters, but adjustments to either of them are primarily to permit you to affect the altitude hold automatic responsiveness and they simply coincidentally also affect the manual override throttle rate.
Gary[/quote]
Hallo Gary,
thank you, thats exactly the 2 Parameters that i was suspecting to help after i extensively studied the docs.
(As i said i am not only an APM but also a RC & Multicopter noob)
But i was pretty sure that they have other sideeffects that i can not foresee and that i most probably do not want.
I simply want to climb / descent faster…
The fiddling with stick curves would give me the perception of having better response but the limits would still be the same, right ?
So i guess there is no singular influencing of the “manual override” climb and descent rates 
((
Well maybe later…
Greetings & thanks
Ender
Pilot_velz_max is the parameter for controlling the descent and ascent rate in Loiter and Alt_hold.
Hello Graham !
GREAT, thank you for sharing some wisdom 
Will try later and report success for other readers !
Greetings & have a nice day,
Ender
P.S. requesting to move “accepted answer” tag from gary to Graham, not to confuse others,
[color=#00BF00]Changed solved attribute as per OP request.[/color]
Guess what… the solution is in the documentation…
=> copter.ardupilot.com/wiki/arduco … T_VELZ_MAX
Hi again !
Ok, tried it out and its much closer to the desired behaviour, thank you again Graham.
Knowing the parameter now i googled for it and +1 on your request to separate climb from descend speed.
StefanG:
Like i said before: i am not perfect and of course i will overlook or misunderstand stuff.
And as it was ONLY Graham who knew this all of us have to reread the docs again i guess 
(Which is in fact never a bad idea…)
Greetings,
Ender
Or it was only Graham who chose to answer because others also think that a question which is answered by the documentation does not deserve the effort of a separate answer.