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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Hello,

What is certain is that the Arducopter software (running on APM or Pixhawk) does not proposes this specific V-tail prop config. Because not only is this a V tail but in addition the motors are spread apart in the front like an H copter (the standard config is having the four motors on a circle, or at the corners of a square).

You canmodify the motor config in Arducopter's code to match this very specific config (and then recompile) but do not ask me what your'd need to modify, i simply do not know. Maybe a community's developer might help here about this.

Thanks Hughes,

As I am new to this site and I am guess you're not, do you know what the general feel is about V-Tail Quadcopters good or bad?

I will look into modifying the code and will post it as a separate discussion to see if it necessary or you tell the APM that it is a quad but alter the PID loops etc...

Thanks Again,

D

I cannot speak to this specific Lynxmotion V-Tail design, but I have a SimpleCopter V-Tail which I really like.  It is running a KK2 board and it is a very sporty flying vehicle. I am learning how to do flips with it which is great fun. The KK2 is just a stabilization board - no GPS or telemetry and not expandable like the Pixhawk.  The lynxmotion pusher V format looks pretty interesting.  The SimpleCopter is a puller V.

I have not seen any Pixhawk V-Tail configurations yet, but I expect it is just a matter of time before someone comes up with a software configuration for it.

I do have the Pixhawk on a NEO 660 Hex frame and it is rock solid.

Thanks Robert.

You say you have a PIxhawk, could you tell me the dimensions of it please (WxLxH). I'm working on my own quad design and want to make sure the body will allow the pixhawk to fit nicely.

Thanks Again.

Hey Dave,

I have a Hunter V-Tail 500 controlled by an OpenPilot CC3D.  It's a TON of fun to fly.  I really like it for FPV because the yaw handles so much more like a tricopter.  I don't think my configuration is powerful enough for a gopro and certainly not a gopro on a gimbal.  To tune the CC3D (no gps) I used a custom motor mix that I found online.  I eventually want to build a v-tail that is controlled by my Pixhawk and I've done quite a bit of research to see what I would have to do to make it work.  To alter the motor mixing for the Pixhawk to support a v-tail configuration, you'll have to modify the source code and recompile.  If you're not comfortable with recompiling, I'd stick with a more simple flight controller like the KK board or a CC3D.

Hope this helps!

-Brett

Hi, Dave,

I have a Pixhawk but it is on a Hex (6 rotor), not my Quad V-Tail.  I meant by my comment that the V-Tail I have is very sporty, not to say that Pixhawk supports the V-Tail configuration yet.

The dimensions may be found on the 3DR store http://store.3drobotics.com/products/3dr-pixhawk.  Leave room on the top for cabling, on the one end for the cabling for the ESC and receiver, and on the side for the USB cable (for programming).

Hi,

(Dave, I like the v-tail, It is so much fun!)

I would pretty much fly this v-tail baby with my APM rather than the KK2 as I do now. Since KK2 supports this v-tail setup, the parameters must exist somewhere.

Does anybody know, where one can get such a parameter list?  Maybe for CC3D or Multiwii?

Thanks in advance

John

Hi John,

You can find the CC3D setup in this thread for the Hunter Vtail:

http://forums.openpilot.org/topic/16043-dialfonzo-hunter-vtail-500/

If you want to fly an APM, I have found (add to the AP_MotorsQuad.cpp):

else if( _frame_orientation == AP_MOTORS_VTAIL_FRAME ) {

    // hack - VTAIL (1=NE CW, 2=SE CW(INV), 3=SW CCW(INV), 4=NW CCW)
                                                           // R, P, Y, TO
    add_motor_raw(AP_MOTORS_MOT_1, -0.7, 0.7, -0.23, 1);
    add_motor_raw(AP_MOTORS_MOT_2, 0.0, -0.7, 0.7, 2);
    add_motor_raw(AP_MOTORS_MOT_3, 0.0, -0.7, -0.7, 3);
    add_motor_raw(AP_MOTORS_MOT_4, 0.7, 0.7, 0.23, 4);

}

OR ...

// front right: 70 degrees right of roll axis, 20 degrees up of pitch axis, no yaw

add_motor_raw(AP_MOTORS_MOT_1, cosf(radians(160)), cosf(radians(-70)), 0, 1);

// back left: no roll, 70 degrees down of pitch axis, full yaw

add_motor_raw(AP_MOTORS_MOT_2, 0, cosf(radians(160)), AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 3);

// front left: 70 degrees left of roll axis, 20 degrees up of pitch axis, no yaw

add_motor_raw(AP_MOTORS_MOT_3, cosf(radians(20)), cosf(radians(70)), 0, 4);

// back right: no roll, 70 degrees down of pitch axis, full yaw

add_motor_raw(AP_MOTORS_MOT_4, 0, cosf(radians(-160)), AP_MOTORS_MATRIX_YAW_FACTOR_CW, 2);

Which should show up in the next build of Arducopter 3.2.  I am trying to get a v-tail of my own flying, but I'm struggling with my APM.  I know I could do it with my CC3D, but I want the APM features.

-Brett

Thank you so much Brett,

this is good advice.

Havn't been through the complete article/thread but I think one can derive the setup for different frames and COGs there.

My mikrokopter which I flew years ago had a setup table (see picture) where one could code in the thrusts for each motor and e.g. could change a +-hex setup to a x-hex setup easily. It was ever faulty for other reasons (bad electrical contact on so many different places) but the thrust setup table should be implemented into APM Mission planner (parameters setup), I think.  

If a v-tail setup will be implemented in the 3.2 version of Arducopter I'll skip the try to code it by myself. Btw - never did that until now ;-))

regards

John

David, and everyone else.

There is already a motor mixing for V-tails in the APM firmware. The problem is that there is no "picture" to click on from Mission Planner (MP). 

To activate it you have to go to the advanced setup and find FRAME. Make that value "4" and hit save.

After that you will have the APM setup for the V-tail config. You might have to play with the PID's a bit to fine tune, but you should be able to at least get flying with that.

I have talked to the individual who has worked so hard on this (name on here is NullVoxPopuli), he says that we should really start seeing in come 3.2v.

Cool!

I will give that a try.

Have you tried this yet? How did it work out for you?

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