One of the problems of WW1 models is that being tall it practically trips over its self. Pretty much why the gears get moved for sport; taller more forward. old free flight models fron the 30s pretty much had the gear inline with the prop. With no control, the plane had to not nose over and be at the best angle to take off by its self. More control, the further back the gear can be. With the high angle of attack that a WW1 plane sits at, the wings and tail are at a stall angle. Air blowing on the tail may be deflected, but it is not aerodynamically flowing around the elevator like in flight mode. As the tail is coming up there is really a short time where there is almost no control, especially on a smaller model. Those crucial seconds of getting control without over control is key.