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.