The first movable rudder

LAST EDITED ON Oct-08-03 AT 09:46 AM (CDT)
 
I came across these photos and saw a relationship to the Spitfire thread. This was my first original design. It was in 1966. I learned to fly on a Magician and, at the time was farther developing my pattern with a purchased Oriental which flew very well.

This Spitfire had a low mounted wing without dihedral. I tried long and hard to get it to turn with similar line tension in maneuvers to no avail. The movable rudder was actually added to the Spitfire to increase the line tension on outside maneuvers. It didn't help with the vertical CG problem, but it did lead me to farther examination of the theoretical advantages of using a movable rudder coupled to the elevators to control yaw. It also became apparent from this experience with this airplane that leadouts must exit near the vertical center of gravity. Wings would have to be mounted near the thrust line or have dihedral if mounted low on the fuselage. The airplane also had a set of commercial machined aluminum shock gears which seemed like a good idea but didn't work either. This failure of the shock gears later led me to designing practical shock gears made of wire which worked wonderfully. I still use wire shocks in all of my airplanes.

With 3/4" of dihedral in each panel, this might have been a good stunt ship. As it was, it was a good learning experience.

Here you go, Al. A piece of history. I believe this model also had your linked movable rudder. Whether it did or not, placing Second to Bob Hunt's Genesis in the 1978 World Championships is testimony to the model.

LAST EDITED ON Oct-09-03 AT 08:36 PM (CDT)
 
I was going to simply edit this thread to add another photo I found of the Rockin, Rollin Spitfire. Shame it didn't fly well, it was sem-eye pretty.

Ken,

Yea, ain't nostalgia wonderful. That was ole Snaggletooth". It was a very good airplane, so much so that I am in the process of building another with updated laser construction and a modern rear exhaust engine. Let's hope it flies as well as its namesake.

>Ken,
>
>Yea, ain't nostalgia wonderful. That was ole Snaggletooth".
> It was a very good airplane, so much so that I am in the
>process of building another with updated laser construction
>and a modern rear exhaust engine. Let's hope it flies as
>well as its namesake.
>
>Al

Yes, nostalgia is wonderful. Al, since you are becoming so adept at CADCAM, how about resurrecting an up gunned version of the Spitfire?

Al,
I used a moveable rudder in 1963 and I doubt that I was the first. Mine moved out when both 'up' and 'down' were applied and it was driven by a separate pushrod back to the bellcrank.
I, and others, firmly believe that your second place back in '78 would have been first if you had been flying Bob's model. The consensus was that you were clearly the better flyer but that the Mustang was difficult to judge because of the tall fin and long U/C.

The consensus was that you were clearly the better
>flyer but that the Mustang was difficult to judge because of
>the tall fin and long U/C.

What is a "long U/C"?

Hi 'zilla,
Just a WAG, but since Dave is "from across the pond", I venture "under carriage".
Bill

In this post of 'infinite rudder control' I am perplexed as to what a 'WAG' is. I thought that was what we were trying to overcome!
Seriously, what is a 'WAG'?

>In this post of 'infinite rudder control' I am perplexed as
>to what a 'WAG' is. I thought that was what we were trying
>to overcome!
> Seriously, what is a 'WAG'?

WAG is an engineering term used frequently to answer "how did you arrive at that design?" Wild Ass Guess!
Steve

We engineers are a bit more sophisticated. We use the SWAG.

Scientific Wild Assed Guess..

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"Join the Army, meet interesting people, and kill them."

Larry, professional marketers are taught the same things at university in Oz. At least I was.

Dave,

The movable rudder wasn't just a rudder connected to the bellcrank to move both on up and down application of controls. It was a concept recgonizing the effect of gyroscopic precession an its effect on the maneuvering flight of a stunt ship. It is not simplistic movement of the rudder outward on both "up" and Down". It is designed to compensate for gyroscopic precesion by moving the rudder to the outside on outside maneuvers and left (inside) rudder on inside maneuvers to reduce yaw resulting from high pitch rates and having a gyroscope on the front of the airplane. I never claimed to have invented rudders, just a practical solution to unwanted yaw during maneuvers which would cause loss of tension on outside maneuvers and unnecessary tension on inside maneuvers. The originality was in the concept rather than the hardware.

Godzilla,
As Bill said, "long undercarriage", but maybe I should make that "Tall undercarriage".
Al,
I understand the function of your moveable rudder and have used it with great results. I think it is maybe one of the greatest advances ever made in stunt flying. It can transform a Nobler.
My point was in reply to your thread heading 'The first movable rudder' and I apologise if you took it as criticism. My system wasn't designed to fight gyroscopic effects which I didn't understand at the time.

Hmmmmmmm..

For a low winger like that, with no dihedral, to take care of the vertical CG problem, how about external leadouts above the wing? I remember seeing something published in Aeromodeller back in the 70s like that. Can't remember what it was now.. semi-scale stunter based on a long-winged European light plane.

First time I saw a 'Rabe Rudder' was in American Modeler. Retroed it onto my first Gee Bee. Tamed an otherwise Wild Beast,as scale rudder had extreme taper to trailing edge. Rabe Rudder gave me the 'edge' in outside maneuvers. I felt clever using it. Thanks, Al. It was what Dolittle would have done, were he in it.