by George S Rossano
(27 October 2022) In previous theoretical discussions of the quad Axel (which can be found elsewhere on this site) we concluded that to successfully execute a quad Axel a skater would have to max out the time in the air (which we take to be about 0.80 seconds) and achieve a peak and sustained rotation rate of greater than the typical maximum in other jumps of 6.0 rotations per second, speculating that at least 6.25 rotations would be necessary.
In his successful quad Axel execution at the 2022 Skate America Ilia Malinin confirmed the former analysis by completing an attempt with 0.79 seconds in the air and a peak rotation rate of 6.25 rotations per second. A series of photographs of the execution allows us to calculate the trajectory of the jump, in height, rotation rate and rotations executed, which we will discuss here.
Like all real world triple and quad jumps, the quad Axel attempt was slightly pre-rotated on the takeoff, and missing rotation on the landing by about 1/6 rotation each. We determine this execution had a total of 4.1 rotations in the air, and consider this a fully rotated jump for a real world (not idealized) quad Axel. By necessity all jumps must rotate a small amount on the ice during the takeoff, while the torque is developed to rotate the jump.
The blue curve shows the flight of the jump reaching a peak height of 0.76 m (30 in). The peak of the jump is just to the right of the 6th data point, near 0.40 sec.
The green curve shows the rotations of the skater and the rust curve the rotation rate during the jump. The skater reaches 95% of the maximum rate by the top of the jump, by which time he has completed 1.7 rotations. For most of the second half of the jump the skater rotates at the maximum rate of 6.25 per second, and completes 4.1 rotations in the air at the time of the landing.
Notable about this jump is that the skater holds the maximum air position until very shortly before the landing of the jump - more so than typical for other examples of triples and quads. Thus the skater lands the jump while still rotating at a fairly high rate, yet is still able to control the landing.
The time resolution of the photo sequence is not as high as we would like to dissect the landing phase with the detail we would like. Nevertheless, we can say that the skater lands with a rotation speed of at least three rotations per seconds, and it might well have been as large as four.
Our goal this season is to be able to obtain future sequences with at least twice the time resolution to better study the takeoff and landing characteristics of jumps.
Copyright 2022 by George S Rossano