Bill McCombs

IT'S HELPFUL for the Free Flight modeler to know that for a given model there is a critical climb angle, at or above which the model becomes spirally unstable. Regardless of the trimmed flight path, straight or turning, when its critical climb angle is reached, the model will always "veer off" or "roll off" into an undesired less-steep spiraling flight which results in less altitude and duration. Unfortunately, this trouble cannot be corrected by trim changes (side thrust, rudder setting, wing-warping, etc.) since it is an instability trouble, although modelers frequently try to do this. The only way to eliminate the trouble is to make a change that increases the critical climb angle sufficiently. Of course, if the critical climb angle is 90°he only other item on the wish list is a practice circle; it will probably take more time to achieve. For now, the racing community is still excited about the smooth blacktop and painted circle markings; a far cry from the pitted and cracked airport ramps that we have had to deal with at past Nats. or more, the trouble will not occur, since the steepest a model can climb is at 90° ("straight up")