Hi

This design feature come from the days of single channel rudder only flying. With the absence of any form of elevator control it enabled the aircraft to pitch up slightly in a long shallow turn which required the rudder control to be pulsed to maintain. With vertical hinge line the model tended to drop its nose in such a manouver resulting in an increase in speed which would produce a "balloon" and sometimes even a stall when the model straightened up after the turn.

It carried on into the reed days one of the best examples around was the Taurus by Ed. Kazmirski. From memory he was the World aerobatic champion in '61 and '62 with this design. I still have a 30 year old example of this model which I currently fly on occasions and it still delights me with its wonderful handling and manners. Even though I fly it with a modern Hitec set full house I can trim it out so it can be flown Rudder/Throttle quite well and have actually taught a couple of people to fly with it in this state!

Clipper7