Origins - Development - Background - Aircraft
Ballet - Quest - Gender - Snap - Weather

by Larry Lowe

The pivotal figure of World Competition Aerobatics that serves to define the difference between the conservative style of flying practiced in America from the aggressive European style is the snap roll, or as it is termed in Europe, the flick roll. A snap roll is initiated by an abrupt push or pull on the control stick which brings the airplane suddenly into a very high angle of attack, accompanied by the full depression of a rudder pedal to select the direction of rotation. This combination has the effect of forcing one of the wings to stall while the other continues to generate lift, a lot of it. The result is that the airplane corkscrews through the air as if it only had one wing. Recovery is an equally abrupt reversal of the controls, returning the airplane to the normal flight regime. The entire affair occurs so quickly that it must be performed using 'muscle memory' much like a dance step-if you stop to think about what's going on consciously, the pilots say, you're doomed. You have to just do it.

Everyone at the training camp is working on one form of the snap roll or another, and the many variations in which the figure can be performed, inside (positive G) and outside (negative G), starting from upright or inverted, on a horizontal, 45 degree or vertical line, full or fractional rotation, present a wealth of challenge for the unlimited competition pilot to master. In addition to the numerous snaps in the known and freestyle routines, there is no telling what kind of snap rolls the pilots will face in the unknown flight, or at what airspeed they will be required to execute them.

Current U.S. Team Judge and assistant trainer Alan Geringer explains the new focus on the figure at training camp. "I think we've tended to accelerate the snaps, that is to make them turn faster. In that process, there's several things you can do. You can do things with the elevator, you can do things with the aileron and you can do things with the rudder that will make the snap happen faster. The one thing I feel we've done [in the past] is we've gotten real lazy with the foot, coming back off the rudder, and started accelerating the snaps with the rudder, rather than the elevator and the aileron, and in that process, we've modified the character where they look very much aileroned rather than snapped."

"If you were to look at a snap roll as it rotates, you would see a line that the airplane followed, and the nose would be moved off that line. There's a pitch and yaw moment that's involved to get it there. If you can imagine a cylinder with a wire down the middle of it and the airplane is rotating around the center of gravity down that wire, the nose is describing a helix on the cylinder, that's the proper character. Whereas if you unload the rudder, the nose moves back down toward the line, and it gets to be more of a roll."

"I think that in Europe, they have been working this technique to maintain that type of character, whereas we've gone the other direction, trying to increase [roll] rate." On way to assure good character is to keep the rudder all the way in throughout the rotation, however that tactic can present its own problems in the partial snap rolls, which Phil Knight explains, are much harder to do than a full snap. "Probably the 45 degree line is the hardest for me to do the half snap on. The technique is unique in that the same rudder you initiate the snap with is the one you stop the snap with. If you got the rudder in, there ain't no more rudder left!"

Anyway you want to look at it, world class technique is no snap.

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