The Mercury Cossor was the first commercial UK R/C set in 1947 and was a Ruddervator design. It was an attempt to have rudder, elevator and throttle (cut) control with a single-channel CW set.
The transmitter had an 8-position rotary switch marked: D (Down), N (Neutral), R (Right), N, U (Up), N, L (Left), N. The switch was quite simple, it had to be rotated clockwise, one position at a time and in between the 8 positions the switch opened a pair of contacts with a cam and follower and it transmitted a CW signal. At the aircraft end the receiver operated an 8-position escapement with a shaft and what looked like half of a propeller blade. In four positions it was free to rotate (in the slipstream) and in the other four positions, it stopped. When escapement stopped, the ruddervator acted either like a rudder if it stopped vertically (with its shape if it stopped vertically up then right, down left) or an elevator if it stopped horizontally (again up or down depending on which side it stopped).
The operation must have been "interesting", before the flight you would need to ensure the switch position and escapement were "in sync". You would launch with the ruddervator freely rotating, then when you wanted control, you had to rotate the switch slowly to the desired position. If you had previously selected left rudder and wanted left rudder again you had to go all the way around the switch again, slowly enough for the escapement to keep up. If the receiver got interference, the escapement could operate and get out of sync and ahead of the rotary switch. If say you were in neutral position before right rudder and interference moved the escapement to right rudder, you could not simply rotate the switch as it would move the escapement on to neutral position before up elevator. What you had to do was turn the transmitter off before rotating the switch so that it didn't transmit while the switch "caught up" with the escapement.
The throttle control was really throttle-cut. In the neutral position before down elevator on the escapement, there was a delayed action set of contacts that would cut the ignition (it was expected that it would be flown with petrol/gas engines), so you would have to wait in that neutral position. But that meant after right rudder, you could not linger around in that neutral position, otherwise, your engine would stop! You would need to go through the down elevator position to the next neutral position if you wanted straight and level.
The Mercury Cossor sets never caught on because they all had faults with their Cossor manufactured valves (tubes for our American friends) and by the time Cossor had sorted the problem ED and ECC had become dominant in the UK. For most models of the period, simple rudder control was far more reliable and only a few years later Rockwood/Schmit launched a reed set in the USA, so full control was available without the complications of a Ruddervator.
If you want to read more about Ruddervator rcfiles.com have some articles from MAN 1948 and 1950
http://vintagercfiles.com/EarlyRCarticl ... rticle.pdf
http://vintagercfiles.com/EarlyRCarticl ... rticle.pdf
http://vintagercfiles.com/EarlyRCarticl ... rticle.pdf
and all the early info on rcfiles
https://vintagercfiles.com/Early_RC.html
I might just try it, just to be different!