Oddly enough, IIRC, when the Dirty Birdy was first made available to the public, there were no knife-edge maneuvers in any of the patterns that I can recall. Knife-edge was still an exhibition maneuver displayed by the likes of Jersey Jim Martin with his infamous Banshee. The fact that the SPA has seen fit to incorporate point rolls and knife edge is kind of disappointing to me because many of the popular models of that era were not designed for that type of performance.

Of course, one can enhance knife-edge performance in even a doggy model by spinning a large diameter prop at fairly high rpm (10K rpm). Could this be why the .91 Pumpers on 30% nitro are favored by a knowledgable few? <G>

Ed Cregger