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Pixhawk With V-Tail Quadcopter???

Posted by David Antwis on February 26, 2014 at 4:01am

Hey,

I am looking into purchasing a V-Tail quadcopter from HERE and was wanted some feedback on the following points as I'm pretty new to copters... been flying RC helis for years but wanted to try something new...

  • Is the V-Tail any good?
  • How would you set-up Pixhawk to work with this format of copter (Quad or Tri)
  • Has anyone done this before or do I avoid this

I want to use this copter for FPV but also have the added benefit of GPS and Mission planner plus the thing just looks cool... any advice is much appreciated!!

Thank you in advance.

Dave.

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Tags: gps, mission planner, advice, pixhawk, quadcopter, setup, tricopter, v-tail
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Replies

  • careyer June 22, 2014 at 2:57am

    Thanks Tom. I can easily calculate the proper CG with my CAD, so i do not worry to much about that.

    I was just wondering if there is a "defacto standard" how a V-Tail-Setup should optimally look like and which works best with the V-Tail mixer implemented in APM.

    There are many varaints of building quads (standard, dat-cat sytle, spider style ...) and from all those variants the standard quad always works the best because of it's clean symetries. More or less my question could have been: "Is there a standard V-Tail design? If yes... how does it look like?"

    Thank you so much!
    Best regards

    careyer

    • Tom > careyer July 5, 2014 at 5:10pm

      Sorry that it took me this long to get back,

      The long/short of it is that there is no standardized way to build a V-tail as far as APM is concerned. The only thing that you have to limit yourself with is the angle in which your tail rotors sit. As long and the angle is correct then you can just make minor adjustments to the PID settings to get the proper yaw.

  • Tim B June 22, 2014 at 2:49am

    Just got a quick clip but managed to do some flying with my Vtail 500 and pixhawk. Will do a better one sooner or later. Was a bit windy / some gusts and this was just a fresh flash of 3.2-RC2 and recalibrated accel but no tuning whatsoever. It did have a tendency to want to shoot high up in the sky once airborne in stabilize, switching to alt hold helped. Tested rotation and tilting left / right / forward / backward. Everything worked.

    Youtube - Vtail 500 - Pixhawk First Flight 

  • careyer June 22, 2014 at 1:05am

    Hi there,

    i always wanted to build a V-Tail Setup but i never did because my favourite FlightControler (APM) did not support it. Now I am happy like a child to hear that support has finally been added! =)

    Right now I am designing my own build (which i want to empower with a Pixhawk) but I have some newbie questions:

    a.) Is it okay to have a 120° angle between the two front booms (like on a tricopter)?

    b.) would it also be possible to have a H-Style front (180° between front booms)? Asking because I want to have a free view for my 3-axis BL-Gimbal to the front

    c.) What angle should be chosen between the two rear booms (where it says 42° in my picture)?

    d.) What length should the rear booms have? Should their lenght be chosen so that the motor-shafts intersect the circle in my picture?

    Thank you very much for answering those noob questions ;-) Forgive me... I am new to V-Tails! =)

    3701764283?profile=original

    • Tom > careyer June 22, 2014 at 2:31am

      Answers as I know them...

      A & B) Yes, and yes. The more angle that you have the more stable it will feel with less roll. With the arms angled in you will have easier roll axis and less stable. 

      C) Kind of the same answer here as for A & B. The wider your angle the less roll that you will have. 

      D) It all depends on where you want your center of gravity to be. If you want it more up front then you will want longer tail booms compared to the front booms... you want the center of gravity to be more towards the back... shorter. I will tell you this, the tails will NOT add as much lift as the front. 

      Best bet is to build it (with out motors), put all your gizmos on it, and find out where you want your CG to be. (Pro-tip - don't make your front end to heavy)

      Hope that this helps answer your questions... I'm a little tired right now so I may have just rambled...

  • John Baldiga June 18, 2014 at 12:38pm

    So, this has been done with a Pixhawk? There are Pixhawk V tails out there?

    • Tim B > John Baldiga June 18, 2014 at 3:37pm

      I've got a Pixhawk on my Lynxmotion Vtail 500. I was taking off and it was spinning like crazy, had to reverse the back motors connection 2 and 4. I was able to take off twice and hover a bit before drifting and letting off throttle and catching / grabbing it. Didn't have enough room in backyard to truly fly it.

      So yea, was gonna take it out for a bigger test but it's been windy so I haven't yet but seems like it's going to work. There is a basic "vtail" config built into the arducopter code now that's what I'm using, unmodified, just had to swap those motor connectors.

  • John Baldiga June 18, 2014 at 9:07am

    I'm currently working on a custom V-Tail. According to the AP_MotorsQuad.cpp file in the link you posted, the tail configuration should be similar to this?

    CONFIG 1:

    3701761878?profile=original

    The other way I represented the "All angles measured from their closest axis" could be this:

    CONFIG 2:

    3701761732?profile=original

    Which should I use? Can anyone out there provide any clarification for, yet another, V Tail noob? 

    • Tom > John Baldiga June 18, 2014 at 9:22am

      If I remember right the setup that you will want to use will be the 2nd graphic. 

      If I'm incorrect someone please chime in.

  • Tim B June 16, 2014 at 2:14pm

    Update: I got in touch with the guy who added the vtail code into arducopter I guess. He sent me a link to the request to get it in to master or what not. From everything I found on the subject I had the motors how they should be but then he mentioned and was in the comments, one of the devs reversed motors 2 and 4 (the back 2) when they added it into the code.

    He stated he was pretty sure he had it right when he submitted it but of course the dev overruled I guess. He suggested swapping motors 2 and 4's connectors if I couldn't figure out the problem otherwise which was the case.

    I did a fresh upload of 3.2-rc2 and recalibrated accel as I saw needed doing if upgrading from 3.1 etc. I managed to take off twice in my backyard without the crazy 360's. Wasn't enough room to really fly but it hovered a bit started drifing and I let off throttle and grabbed / caught it out of the air both times. So was the 2 back motors connection to pixhawk for sure.

    Only other problem I had was it was a bit twitchy some times when throttleing up on the ground. It was like the one right front motor was over thrusting and causing the frame to teter. Not sure if that is normal or not when trying to lift off and the frame is not perfectly level because it is trying to compensate for the not level?

    Anyways, gonna probably go to the park in a bit and see if I can actually fly, fly it now. Thanks for the replies.

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