[LOENHARD]

hey guys. i'm a newbie here.
i.m trying to make my custom dualcopter to fly but looks like everything i try doesn't wanna work. so i came here to look for advices. i uploaded a video with it where i.m trying to show you that everything looks allright. i think the only problem is from pid, i don.t know how to calibrate it.
i mention that i used libre pilot/ helicopter / coax 2 servos 90 degree, but instead of swashplate i connected the servos to those 2 things beneath the rotors(i don't know how to call them in english, and btw i apologise for my poor english)

anything that might help me?

i can.t upload videos.. so i posted a picture

[TheOtherCliff]

A video would help us guess what is wrong...

Upload it to youtube and post a link here.  If the link is done correctly (youtube.com, not other sites) even the picture will show up here.  Even if it is a link to another site, the link will still be visible and work even if the picture doesn't show up.

If you have proper mixers so that yaw comes from reducing one motor while increasing the other, and thrust comes from increasing both motors, and you have servos attached to the clear control surfaces for roll and pitch, then it should work.  Center of gravity is one issue.  If CG is below the props then it seems it shouldn't even require stabilization to fly.

If it doesn't oscillate when you try to take off, then increase PID until it does.  Maybe start with I=D=0 and just make P high enough that it starts to act better but does not oscillate.  With P a bit below oscillation, increase I till it oscillates again and then reduce somewhat.

You could suspend it from a single vertical string and get yaw tuned fairly well.

[LOENHARD]

thx for your time theothercliff
you can find the video here:

www.youtube.com/watch?v=Aoau_uvP97Q&feature=youtu.be


as you can see everything looks working. the problem is everythime i.m arming one of the plate moves a little bit from the normal position and when i.m disarmin the plate moves back in the normal position, i think is because the initial feature was for swashplate for the heli to move forward , but i don.t need that feature.. and if is so, where can i find it to disable it.
thx again.

[TheOtherCliff]

I don't know what you mean by "swashplate for the heli to move forward"

That may be caused by leveling calibration being a bit bad.  It can be adjusted with Attitude -> RotateVirtual

After arming, and with a small amount of throttle, try moving it by hand in direction that the vanes indicate.  You will probably see that the vanes straighten out.  That angle is what it thinks is level.

[LOENHARD]

thanks again. i solved that problem by leveling and attitude/ rotetevirtual.

but it looks that i.m having problems with the yaw. on manual i get enough thrust to lift it in the air but it starts to spin. when i put axis lock on yaw it keeps it in position but i don't get enough power to lift it.

[f5soh]

Be sure both propellers (one CW, the other CCW) shows the marking face (where the size is, like 10x4.5) pointing up side and of course giving thrust to the bottom.

[TheOtherCliff]

One motor/prop is stronger than the other.  By noting which way the vehicle spins you can tell which prop is stronger.  I bet large money that the top motor yaw is overpowering the bottom motor yaw.

My opinion: You should start with both motors being identical with identical sized props (one CW and one CCW), but you should be willing to change props.  In particular, the lower prop lives in the downwash of the upper prop and may need to have more pitch (and maybe very slightly less diameter) to have the same thrust and yaw effect.  Increase the weak prop pitch until you fix the problem.  A reasoned thought hints that you may have to almost double the bottom prop pitch to fix this in some cases, so don't be shy, maybe 10x4.7 on top and 10x6, 10x7, or 9x8 on bottom (some wild guesses).

You could put a slightly higher KV (and thus higher RPM) motor on the bottom rather than change to a prop with more pitch.

The bottom prop is windmilling because of the top prop and so the bottom motor can be larger than you would normally run on that motor.

After hovering successfully for several minutes, feel the motor temperature.  Neither should burn you and the bottom one should be a little cooler because it is in a better air flow.  Either that or measure motor RPM or individual ESC throttle signal levels to make sure they are about the same when hovering.