A friend of mine has copter that takes off perfectly in stabilize and switching to PosHold it flys very well, but when trying to take off in PosHold, the copter pitches backward until it tips over. Hdop is good and there are no trims - I want to help him but I’m completely stumped!
Again, in stab mode, it takes off perfectly. I should note that this problem appeared since he’s been using larger props. Gains have been increased quite a bit to no avail.
Typically I don’t take off in PosHold. If it’s not Stabilize, it’s Althold, then I will switch to any of the GPS assisted modes. Has your friend tried that? Does it do the same thing if this friend has taken off in AltHold?
Thanks BigTulsa, GertJL - The copter is supposed to do auto missions with automatic take off, my copter can do it no problem. The other reason for take off is PosHold is we want to use a joystick for control. Again, this works very well on my copter.
BigTusla, The same problem occurs in AltHold. PosHold take off works fine with smaller props - only when he switched to larger props did the problem appear.
Yes, initially and was working fine until the props were changed, when the problem started. Going back to the old 18" props makes the problem disappear. Perhaps a good idea to do that again anyway.
From the video I see part of the problem is that you are trying to take off too slowly.
I have found, especially with new builds, that they drift on take off with no stick input to pitch or roll.
So, either try to jump it off the ground, only needs to be a few centimetres, not a few meters, or apply some corrective stick input while attempting to do it so slowly.
You also have not let it go very far before cutting the throttle.
If you are doing auto missions you will note that auto takeoff is quick, it does not hang about near the ground.
The bigger props might have altered the response time considerably, so do not expect the same flight characteristics, and PID tuning might be needed.
Prop changes will definitely alter the response…larger props decreases the amount of rotation the motors need to take off, but increases the torque required as well as increases power usage. Also, if you are using CF props, you need to verify that the props are balanced.
