L Edge

Master member
When you build an experimental or modify an existing model, you may find that you lack a rudder to control your model yawing.

For instance, a model I made had elevons and 2 vertical stabs. When there was a cross wind or I did a high angle of attack(STOL), it would start to yaw and there was no control. Not good. If you watch Josh's or FT crew, you can spot cases like that.

Almost all airplanes have rudders(vert stabs) and to have rudder movement, sometimes it involves extra weight to incorporate it.

So, why not this? All it takes is a servo, a large servo arm and a foam made rudder which is hot glued to the servo arm. I then carved out a small section of the rudder to tighen the screw when mounted to the servo spline so it doesn't fall off and into the prop. Then I tape the gap.
It is mounted in between the motor mount and extends back to about 1" from the prop.


Here it is top view being deflected.

Another design used on a F-22 where it is above and below the fuse in the rear behind the prop.

So, does it work. Yes, especially at regular flying. Have full control of yaw in wind is always nice to have.
At high angles of attack and slow speeds, I needed to make adjustments(high deflections due to little airflow) and ended up with high movement of rudder to pin point the proper location. So to make it a smaller movement, I used negative expo which gives high deflection for little movement.

neg expo.JPG

So, to handle regular flight, I use mode 0 which is a straight line. For landing and high alpha with yaw problems, I use mode 1 with negative expo. Works for me. So, yaw problems, design your "UDDER RUDDER".



Legendary member
I was thinking of something similar for my SR-71 build.
Good to know it's a sound idea if she needs them! (y)(y)


Elite member
Yeah I think it is cool too, and different than the FT Vector. The Vector may have a rudder but isn't it is driven in the conventional way with a pushrod and servo horn? This is neat because it is integrated right into the servo and therefore gets bonus points for style.