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Rudder for Tricopter

Karl0508

Junior Member
#1
Hi Guys

New to this forum and love RC i have raced alot of cars over the years and want to take to the skys :)

I have been watching the channel for the last few months (like 6 months) and after watching the quadcopter vs tricopter review and some tricopter reviews decided this was the way i wanted to go it looks like fun, a tricopter sounds like more fun and would like to build one and then if i wanted to d photography might move to H quad copter.

I love the tricopter T and Y design however after having heard of the common problem with the Yaw servo, i started thinking and my mind automatically went to using a large rudder under the 3rd motor to control yaw.

Has anyone tried this? and also is there a better solution?

I will do some modeling of this and will post any photos of ideas i get
 
#2
One of the reasons people choose a tricopter over a quad is the additional yaw authority provided by tilting the rear rotor left or right instead of relying on torque induced yaw in a quad by speeding up and slowing down the pairs of counter-rotating props. Adding a fixed or movable rudder to a tricopter would only function during fast forward flight and would provide little to no control during hover maneuvers.

It would be pretty cool to see, but I doubt it would be very functional. The control board are already compensating for yaw drift using a heading hold gyro much like a regular helicopter. In order to make a rudder functional, you'd probably have to disable the heading hold gyro and switch to a rate-mode gyro (a gyro that only compensates for rotor torque and doesn't lock on a particular heading).

As with anything, give it a try and post your results!
 

Karl0508

Junior Member
#3
Thank you for the quick reply!
My theory was if the yaw from the motor is used to push the air at an angle to control the yaw using a rubber to control the air direction should work the same?

Does that make sense?
 

razor02097

Rogue Drone Pilot
#4
Hello Karl0508 welcome to the forum wave1.gif

I haven't really heard of someone trying the rudder idea, there would be a lot to consider. There are other options though such as the Y4 where you still have the tricopter frame but yaw is controlled by a coaxial pair of props on the tail. Or the Y6 which has 6 motors in a coaxial configuration.

The biggest problems happen when people crash the tilt mechanism can break or people buy cheap servos and the gears strip out.
 

Karl0508

Junior Member
#5
Hello Karl0508 welcome to the forum View attachment 53133

I haven't really heard of someone trying the rudder idea, there would be a lot to consider. There are other options though such as the Y4 where you still have the tricopter frame but yaw is controlled by a coaxial pair of props on the tail. Or the Y6 which has 6 motors in a coaxial configuration.

The biggest problems happen when people crash the tilt mechanism can break or people buy cheap servos and the gears strip out.
Thanky you

I was thinking about an Y4 but i'm not sure of what control system i would need i was looking at openpilot but doesn't seem to have the option :(

Would a Y4 be as agile as a Y3?

I've attached 2 pictures of what i was thinking
2.jpg 1.jpg
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#6
It has been done before (this is the third such post on this forum alone I've seen . . . but I can't seem to find the other two :p ).

It does work, even in a hover, but the sizing of the rudder is fairly critical -- too small and you can't cancel the torque, let alone have any control authority, but the bigger it is, the more susceptible to crash damage it becomes . . . and you end up with another broken servo :(

As far as the mix, if a Y-4 isn't supported, Y-6 could be used (front left and right motors will need to go to rotationally reversed ports of each other) or it can be custom mixed on a wide variety of control boards: Pitch and yaw are mixed on all 4, Roll mixed only on the front motors. If you set your CG right, you won't even have to adjust the throttle mixing between the strong tail and the nose.

. . . and no servos to break ;)
 

Karl0508

Junior Member
#7
It has been done before (this is the third such post on this forum alone I've seen . . . but I can't seem to find the other two :p ).

It does work, even in a hover, but the sizing of the rudder is fairly critical -- too small and you can't cancel the torque, let alone have any control authority, but the bigger it is, the more susceptible to crash damage it becomes . . . and you end up with another broken servo :(

As far as the mix, if a Y-4 isn't supported, Y-6 could be used (front left and right motors will need to go to rotationally reversed ports of each other) or it can be custom mixed on a wide variety of control boards: Pitch and yaw are mixed on all 4, Roll mixed only on the front motors. If you set your CG right, you won't even have to adjust the throttle mixing between the strong tail and the nose.

. . . and no servos to break ;)
Wow thank you for the help!! i like the Y6 its just the setting up, would you recommend a controller or is the open pilot a good choice?

This would be my first build and a tri copter just looked more fun, would a quad be better for a first build??
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#8
IMO, Open pilot stinks, but the controllers that the OP ROM runs on can be quite good.

Have a look at Tau Labs. It's a fork that's shown dramatic improvements and hasn't gotten sucked into the closed-source forking. I've got it running on my CC3D Atom board, and the transition was night-and-day better.

As for first builds, I would lean toward a quad, but the only major issues between quad and the Y-4/6 are sorting out the top/bottom motor mount and getting the mix working right. Neither of these are hard for those with a knack for tinkering. The Tri's servo (even with a tough tilt) can be such a weak link in both mechanical strength and controllability, IMO, it's something better left for a future project.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
#10
IMO, Open pilot stinks, but the controllers that the OP ROM runs on can be quite good.

Have a look at Tau Labs. It's a fork that's shown dramatic improvements and hasn't gotten sucked into the closed-source forking. I've got it running on my CC3D Atom board, and the transition was night-and-day better.

As for first builds, I would lean toward a quad, but the only major issues between quad and the Y-4/6 are sorting out the top/bottom motor mount and getting the mix working right. Neither of these are hard for those with a knack for tinkering. The Tri's servo (even with a tough tilt) can be such a weak link in both mechanical strength and controllability, IMO, it's something better left for a future project.