MultiWii

hi,

my Y4 Vtail flies nice so far.
i dont use Vtail mixing, motors have same spinning direction as QUAD

there is only one small issue.

when given YAW only while hovering, the cotper flies a circle instead of turning around at one point. its a very small circle (about 40cm diameter).

is there very little "roll" involved?

how could this be solved? change PIDs , or mixing in software?

i use 4x 1000kv motors, front motors 10x4, rear motors 8x4, rear motors are 30° angled, COG is in the middle (arms each 120° + same length )


any ideas?

Care to share a picture or even better a video? If not, maybe the CG and the Line of Thrust (Center of Thrust) do not match up.

hmm, dont have video, but a bad photo
maybe i could make a bad video (cellphone....) tomorrow




the back motors could be mounted nearer to each other. atm its possible to use 10" props rear too, but thats not needed. then theres too much thrust at backside.


its not a big problem with the "circle flying", it even looks cooler than turning just on one point.
but if pure yaw turning is needed, i would like to be able to adjust it somewhere....

Others may have a difference opinion however, from what I see in the second picture, your copter is going to YAW around the greatest mass which is the battery.

thx, you might be right, i didnt thmk about that until now..

copter weight is 650g, battery 3s about 200g?

the battery was put there to get COG exactly to FC....


but i ll test tomorrow with battery on top of FC, and with a second battery too.

flight time with 2200 3s is about 15 minutes now.

You should try to use the patch I've made for dynamic Vtail mixing and try those différent configuration.

If you don't want it to fly like a tri, but more than a quad you should use at least the Yaw compensation, and if you want the Roll &pitch too.

Use the patch below:
viewtopic.php?f=8&t=2033&start=10#p18663

#define VTAIL4YAWCOMP
#define VTAIL4NICKCOMP
#define VTAIL4ROLLCOMP

copterrichie wrote:Others may have a difference opinion however, from what I see in the second picture, your copter is going to YAW around the greatest mass which is the battery.

you were right.

i made a lighter bat-holder construction, and put the lipo closer to COG.

now it flies perfect, far better than many quads + hexas i built earlier - no need for vtail mixing, just Y4 with stock PID settings.


for me the big advantage of Y4 over quadro is, that i can see its direction in air far better, and YAW is very direct, and it even looks cooler..


.