• Without knowing the specifics of those components, I think the logical choice would be as you describe.  You can always plug it in and check the radio cali screen to see what's what.

  • Ok, thanks Leonard.

    I'll try to be more patient considering hard winter has set in. It isn't bad flying, but should be more stable in windy conditions as big as it is. I was seriously considering getting out of the co-axial copter business altogether, but will wait for the changes in AT.

  • Why won't the 'Lock Pitch and Roll Values' box stay unchecked after writing the parameters? After each AT, the box is checked and all the Pitch/Roll values are the same.

    Today I took the laptop with me, unchecked the box, saved it, did AT, refreshed the parameters and there it was again; box checked and Pitch/Roll values still identical.


    • Developer

      Hi DG,

      Looks like your autotune isn't finishing. Do you have a log?

      • See attached. I don't recall it necessary to unplug the power after disarming, turning AT off. Maybe that is the problem?

        If you see anything else unusual feel free to critique. And pay no attention to the battery FS least it worked as instructed. :)


        • Developer

          Hi DG,

          Could you tell us about your frame and maybe add a couple of photos.

          Your autotune is maxing out on each axis and that is why your values aren't changing and are the same. I suspect that mission planner is then seeing that they are all the same and enabling the same values box.

          Your copter is an interesting case as I haven't seen a copter got to maximum on all values.

          • It is a Sky Hero Spy 750

            KDE 2814XF-515 motors

            HobbyWing XRotor ESC (latest AT was done with default intermediate timing)

            MS 4s 10000mah 10c battery secured full length with velcro and two straps

            CSGshop Neo-M8N GPS/compass

            3DR Pixhawk FC

            3DR Telemetry

            Frsky X6R rx

            14.5.5 Gemfan TM style props on top

            15x5.5 Tarot TM style props on bottom

            The ESC's are mounted in the arms and are a snug fit.

            5efBTMK.jpgWithout canopy and before Neo-M8N GPS installed. Pixhawk is mounted using one layer of Kyosho gel tape on top of four plexiglass standoffs (to provide access for wiring). The vibration levels seemed ok so didn't mess with it.

            AqzeIM9.pngIf you look back a few posts, I had problems with yaw wonder and instability with Y6B settings which you suggested changing the Loiter and Yaw parameters and also the Rate for pitch and roll in order to be good enough to do AT. The PWM from top to bottom motors were not correlated, but after using 1" smaller props on top it worked much better so I returned the Loiter/Yaw parameters back to default before doing the last AT.

            The copter takes off perfectly straight and can hover inches above the ground. I still question issues with the ESC's however (this is the fourth one), if only slightly, but the HobbyWings seem better than the others; have not tried high timing on all 6 yet, experimented with top props on high. I'm really beginning to think KDE motors should be used with KDE ESC's.

            • Here is the power area; homemade PDB using .040" copper plates with bullet connecters soldered on them and housed in a 3d printed "coffin". I tried to keep it simple and tidy to avoid the chaotic spaghetti bowl my projects usually end up as. The 12 awg wires have since been replaced with 14.


              • Leonard,

                   There is a lot of "dirty air" between the props. I've discussed this with someone that has a lot of experience with Y6 designs and he says the closer the top/bottom props are to each other, the less efficient they are,  the performance degrades and the copter can behave oddly especially in more windy conditions. 

                Right now there is about 3" between the motor prop surfaces. He says with this size and weight copter, it should much more than that, like 4" minimum.

                What do you think?

                • Developer

                  Hi DG,

                  The coaxial prop set up is very complicated. I don't think anybody realisticly tell you that 4" is better than 3". There are simply too many variables.

                  I can confirm that the lower prop is working harder than the upper prop but when I tried a bunch of combinations for the 3dr coaxial designs there was no clear trend. During this process I read all the research literature I could fine and discussed this will many people.

                  What I found is the performance varied greatly depending on the diameter, pitch, manufacture, model, motor kv, airframe mass. There were no clear trends that made it easy to predict what the best combination would be. However, there were some combinations that performed much worse. So provided you avoid the bad combinations, issues like ease of maintenance, availability, and cost are probably the deciding factor.

                  When I did my work on the 3dr Y6 I was looking for combinations that maximised the flight time, minimised the difference in pwm outputs between the upper and lower motors (this ensures maximum lift at full throttle), and resulted in as even motor and esc temperatures as possible.

                  Sorry I asked to see your copter again. I loose track of who has what airframe. As I said last time, nice copter :)

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