The Hunter-Vtail 500mm frame, available from QcRc.ca, is constructed in black G10 and uses aluminum standoffs. It uses an unusual arrangement of motors, with which "the yaw autority is not only managed by the torque of the motors, back motor are producing a vector of thrust that push the tail of the copter one side or another, so it move really fast. Another great thing is, the center frame go way in the front allowing you to place a camera to fly FPV or film a HD image ( such Gopro camera ) that will not see propeller !" [sic]
It should be noted that the vendor recommends the use of the Rushduino Flight Control board, and this frame and configuration has not been tested with APM yet.
Selling at $95 Canadian, maybe some members would consider buying some of these for a developer or two who might consider spending some time working out APM support for this frame? Any volunteers for either role (donating frames, coding/testing APM support?)
Comments
Where can you buy this frame?
Do you know how much this frame weighs? I am currently designing my own v tail copter, hopefully with a 130 degree angle between the two tail motors. I was running the numbers on the parts I have already decided on and needed numbers on the frames mass to estimate my max flight time and payload capacity.
So how can I upload the file ???
Initially I also though about loss of Thrust from the back motor, but if you guys look at properly, the CG is more to the front part, so we mount APM2 on the front side. I've look at Multiwii code and the vector ratio for Aileron and elevator is the same like X Quad.
Here is the codes includes Y4 motor patch, the code has not been test cause I don't have frame, Max Yeo too busy to come to my place to test.
Motor Patch
I can't attach file in blog comment so I post the file to my blogs.
In Summary the motor patch is same like Quad X, except:
1. Front motor not involve in YAW
2. Back Left motor make CCW yaw and Back Right make CW YAW.
Ok, 24% lost power intead of 30%.. ;-)
The tail angle are 40 degrees ...
Bigger props and motor does not address the efficiency loss. The loss is due to the two back motors needing to basically loose 30% of it's power to provide yaw, as R_Lefebvre calculated. You waste that power even when you're holding yaw, as opposed to a traditional quad. In the trad quad, when not yawing, you divide the power equally between motors, and all that power is providing lift.
That might be a bit off. Since you're get 70% lift on the back motors only, that means you'll be capped at 70% for the front motors as well, to maintain level.
Personally, I think that any time you start angling the motors for yaw, you might as well just go to with the traditional heli design, and use one large rotor and a small tail rotor. You'll get more efficiency from the larger main rotor blades.
The efficiency loss is probably around 15% total. Not the end of the world IMO.
I base that on Cos(45) is 0.70, so they downward component of lift is only 70%. So a 30% loss on 2 out of 4 motors, so 15% overall. If the angle of the tail was only 30 degrees instead of 45, you'd still have tons of yaw authority, but also only lose about 7%.
I have been thinking about making a hexa v-tail with two close-set motors on each forward arm. Of course, the big problem with this is, if it's one of the tail motors that goes, you pretty much lose yaw control, so it really defeats the purpose of using a hexa.
Loss of tail lift, due to the angles of the tail would make this thing significantly less efficient than a plain quad, I would think. That crossbar in the tail is definitely needed to keep the tail motors from sagging, and over time might loosen up and cause misalignment and doesn't look like it will survive a mild crash.
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