Stooge is the common expression for a mechanical release by the controlline folks as well as some of freeflight fellows however for those who use rubber power, it was more to support the airplane so the motor could be stretched and wound with a winder.

I used this one as a controlline stooge for years without the servo and just a pull line. Now it serves well as an aerotow release with mods for my glider tug.

It is not really appropriate for what you want though, however if you can get ahold of the January/February 2012 issue of Sam Speaks. This is the magazine of the Society of Antique Modelers, perhaps a member can copy the photos for you. There are pictures of a stooge that could be built with plenty of size and heaft for your ship and its very simple made mostly of wood. This one use's an articulated horizontal tail stops and a trigger out behind the tail and release's them just by stepping on it.

I built a trigger release stooge one time just for Q-500 V tail Pylon racers one time just for those times when practicing alone but this one I described is much simpler and can be made with the heaft needed.

John