In looking thru old pics of mine (for my twin boom pushers) I found these copies .
The split rudder was done by me at the request of a pattern competitor/ TOC flyer.
The setup was basically two panels . internally braced which could open /close porportionately.
The idea was to reduce down line speed ala the dive brakes on some old full scale military stuff.
It turned out to be a mixed bag , as the vertical drag profile of the model changed as the rudders split.
So - I had to mix elevators with the mixed rudder controls.
This also mixed with engine control
I use the then new JR10 channel transmitter which allowed cascaded mixes (they called it included mix).
This took some time consuming testing (ONLY WAY to do this one) to get the deployment to NOT cause a pitch change -on vertical downlines.
Have any of you other old timers ever worked with similar full scale devices - did it work or did you do as I did and simply tos the thing .
By the way, my friend used his setup I made, in contests where it created a bit of a stir.

That's really interesting, Dick. I remember seeing this back in those days, but didn't know it was your idea.

Also, I hadn't thought about the pitch issue... Always assumed this was done with some kind of a sliding servo tray. (like some people use for elevons)

I recently attended the Don Lowe Masters, and was reminiscing with Ivan Kristensen about the days when pattern guys were getting a little too "gadgetized"... variable pitch props, flaps, dive brakes of different sorts, inflight mixture controls, etc.. I think that, for the reasons you mentioned, they're all glad to be back to basics, control system-wise.

Anyway, now I finally get to say to the person (you) who came up with this idea... "Cool!" Something like this could be used today, to create B2-ish split-drag surfaces, dive brakes, or other interesting control functions. Thanks for sharing the photos with us.

I helped a student team put a setup like one of these on a payload lifter quite a while ago. The problem was that planes optimized for lifting sometimes had trouble dumping altitude for landing. The split brake was inspired by the space shuttle, and worked well where nuetral trim wasn't so critical.

I thought this kind of setup was somewhat common if not widespread back in the "gadget" days.

well it is a trick - but making it work correctly was more than a trick.
The pressure on the stabs change as the rudders deploy. also there being more area high than low - caused a pronounced pitch UP.
the trick was to balance the correct amount of down elevator mix with the throttle shut down curve.
the rudders opened progressively during the last part of the throttle low stick settings.
This is really a cut and try setup as the selection of CG and the resultant elevator trim made it a basket of snakes
I figured it out and so did my friend Rojecki -
you had to fly the things to see how the inter reaction worked.
If it was common -I did not know of it -