Home Forums Everything about the Bicopter Bicopter 10% Dihedral Mount

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This topic contains 14 replies, has 3 voices, and was last updated by  Kevin_Erik 4 months, 2 weeks ago.

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  • #60189

    Kevin_Erik
    Moderator

    Thingiverse Link https://www.thingiverse.com/thing:3220102

    For use with BlueBird BMS-385DMAX (13 mm wide) Servo but keep in mind that this should also work with Davids (12 mm wide) servo with a little modification. https://hobbyking.com/en_us/bms-385dmax-digital-servo-metal-gear-4-2kg-15sec-16-5g.html?___store=en_us

    Impossible Tilt Motor Mount https://www.thingiverse.com/thing:3099720/files

    Kevin

    #60193

    Kevin_Erik
    Moderator

    Keep in mind that updates as they’re made will be posted on Thingiverse.

    #60194

    I’m following this with interest 🙂

    #60203

    Kevin_Erik
    Moderator

    @Davd

    If all works to plan, i should have these printed from Carbon / Onyx (Nylon) and in hand by the middle of next week. Each set will be aprox 8 – 10 grams, not counting the motor-mount. (figure 13-15 grams total) This should be pretty close to the weight of the stock mounts (12 grams) but i plan on refining the design more after the Fit / Flight check.

    Whole reason i designed these was that the sOat mounts are still an unknown. (Yes i have a set) Thus rebuilding the Copter to install something thats still evolving didn’t sound like much fun. Especially when i can just fly with mounts that install using only Zip-ties. Later if sOat becomes a reality i can take the leap.

    #60220

    jstremmler
    Participant

    Hi Kevin,

    can you pls explain what is the advantage of your Diheadral Mounts against David’s stock mounts for the bicopter?
    And btw jihlein and myself, we are flying with the OATs adapter….
    So isn’t that a reality?
    Servos on the OATs adapter are mounted, just like with the standard motor mounts, with Zip-zies. I am using BMS-21HV servos which are very fast which should be and advantage for a bi

    • This reply was modified 6 months ago by  jstremmler.
    #60225

    Kevin_Erik
    Moderator

    @jstremmler

    Yes your flying but can you fly backwards without shakes, while still having a really responsive copter? Thus far I’ve not heard from Jihlein thats he’s at that point. Till then i thought I’d explore another angle.

    Now as for the question: Dihedral mounts can offer stability at the cost of efficiency. This is in use by a large number of commercial Quads just for that reason. In a nutshell, the prop’s thrust is diverted away from the center-line of the copter. This helps the copter avoid it’s own wash.

    #60231

    jstremmler
    Participant

    @kevin, sure I can fly backwards and my bicopter flies great backwards once I have done the transition from forward to backward flying smoothly with my sticks. But once the bicopteer is flying backwards its flying great.

    Two more questions to your Dihedral mount:

    1. What angle did you choose?
    2. How can you mount the motors if the axis is going through the motor like in your picture above and are you using ball bearings for the axis?

    #60235

    Kevin_Erik
    Moderator

    @jstremmler

    Pleases post video of the flight, especially the reverse flight.

    1) I’ve chosen 10 Degrees offset as it’s enough to have a noticeable effect without getting crazy.

    2) Both the Servo and the Support mounts are angled so that the Servo / Motor Mount can remain unchanged. See the attached “Better View” for details on the Servo in “Blue”. In the image shown, the Servo is a dummy object created to help provide a better reference when designing the mounts. This isn’t part of the design but was left in the image to be better highlight the angle.

    Kevin

    Attachments:
    #60255

    Kevin_Erik
    Moderator

    Installed and flown!

    Will need some tuning work, yet it was stable and the oscillations were lessened.

    Kevin

    #60259

    Kevin_Erik
    Moderator

    Been making some progress refining the design.

    Attachments:
    #60305

    Kevin_Erik
    Moderator

    Completed the design for the new motor mount. (shown in green)

    #60354

    Kevin_Erik
    Moderator

    The latest 10 degree Dihedral prototypes have arrived printed from Nylon / Kevlar. (Servo Holder and Support Arm)

    1st round prototypes: 7.8 Grams
    2nd round prototypes: 5.1 Grams

    Note: Was previously using the Impossible the impossible Tilt-Mech Support and David’s Servo holder. Together those are approx 5.8 Grams.

    Attachments:
    #60586

    Kevin_Erik
    Moderator

    Added the Turnigy S306G-HV Servo to the Custom Dihedral mounts. Completed the Auto-Tune with the Servos @ 7.2 V / 330 Hz! By far the smoothest and easiest Auto-Tune I’ve done.

    Overall Tau of 20ms !!!

    Log of Autotune 17-Dec-2018, with Dihedral Mounts, 7.2 Volt Turnigy Servo & DAL 6045 2-Bladed Props.
    http://dronin-autotown.appspot.com/at/tune/ahFzfmRyb25pbi1hdXRvdG93bnIYCxILVHVuZVJlc3VsdHMYgICA5Ia3mQkM

    Log of Autotune 28-Nov-2018, with Dihedral Mounts, 6 Volt BMS-385 Servo & DAL 6045 2-Bladed Props.
    http://dronin-autotown.appspot.com/at/tune/ahFzfmRyb25pbi1hdXRvdG93bnIYCxILVHVuZVJlc3VsdHMYgICApPXBkgkM

    Log of Autotune 16-Oct-2018, with Impossible Tilt-Mounts, 6 Volt BMS-385 Servo & DAL T5044 3-Bladed Props.
    http://dronin-autotown.appspot.com/at/tune/ahFzfmRyb25pbi1hdXRvdG93bnIYCxILVHVuZVJlc3VsdHMYgICAxI_SkwoM

    #60742

    I got the 3D printed parts Kevin! Looks great. You really can’t see the layers.
    I’ll throw them on a copter when I get some time. Things are crazy as per usual. But at least I’m back in Sweden for a bit now.

    #60760

    Kevin_Erik
    Moderator

    Please keep in mind that those mounts are very much a work in progress. Hence your feedback is critical to process improvement. Beyond that, the blade clearance on top of the Servo will be tight due to where the Servo cable pokes out from the case.

    Side Note: Any chance you can share the design specs for the bicopter frame? I’m wanting to rework the canopy to add FPV. While i have flown FPV, my current design IS based off what i can measure. (using Runcam Mcro with intergrated transmitter) Thus it would take a lot of time consuming trial and error to get it 100% right without the original files.

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