GP

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Another take-off problem
« on: February 06, 2017, 11:22:05 pm »
Hi Guys, another total newbie here with a problem I can’t seem to solve.
 
I recently made a Chinese ZMR250 clone (5030 props, 3s battery) with a CC3D F/C flashed with LibrePilot 16.09.  I built it to learn about quadcopter building and to try some simple photography with so it has a Firefly 7S camera on top.  Because I want it to fly smoothly (I’m still learning how to fly it too) I’ve used the default PIDS and I have LibrePilot with Stabilisation on Basic and it works pretty well and is very easy to control when hovering about.  But, the thing is a devil to take-off and tries to flip over back wards or sideways no matter how gentle I am.  The only way I can get it to take off is to punch it away quickly, wrestle with the controls for a few seconds while it careers around the place until I finally get it hovering on half throttle and then all is OK!  Are all ZMR250’s this tricky to launch?

The gyros are calibrated as are the esc’s, the CG is central and I wait about 10 seconds after arming before trying to take off but it’s always the same battle.  Any suggestions, please?

 One other thing, it is very jittery when descending vertically, is this likely to be because it is in it’s own propwash or can I possibly tune it out (or a bit of both)?

Many thanks


Re: Another take-off problem
« Reply #1 on: February 07, 2017, 06:56:31 am »
Two different issues.  First, you need to arm, throttle up and take off quickly, and punch it a little to quickly get at least knee high.

Don't take off from a slope.  Don't bring the throttle up slowly.

Second, a bit of wobbles when descending is normal.  If you are travelling horizontally a bit as well as descending it's not nearly so bad.  Tuning PIDs correctly (as high as they can go without oscillation) is the right way to tune, and helps it too.  Also, TPS (stabilization page) is designed to be able to help this too; adjust the left side of the graph higher so your PIDs are higher when using low throttle.

GP

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Re: Another take-off problem
« Reply #2 on: February 07, 2017, 06:38:54 pm »
Thanks for the advice, guess I'll have to delve into advanced tuning and TPS then..........    ;D