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Is Hanyu Quad Axel Quest a Fool's Errand?

by George S. Rossano

(26 December 2021)  Yuzuru Hanyu won his sixth Japanese national title with 322.26 points. In his free skate he attempted the first quad Axel in competition, a jump he has set his sights on for several years, and a goal that has cost him injury and missed competition this season in the ISU Grand Prix.  His attempt in Saitama was missing more than one-half rotation and was landed  on two feet.  A downgraded quad Axel with a GoE of -5 has a value of 4.00 points, less than a base value triple toe loop.

The attempt is the first jump in his free skate program

In In Search of the Quad Axel we discuss the height and rotation requirements to successfully fully rotate a quad Axel.

Playing the above competition video at one-quarter speed and measuring the time in the air several times, we come up with a time in the air of 0.75 seconds.  This is about as much time in the air that elite skaters ever achieve.  To fully rotate an attempt with that time in the air requires an average rotation rate in the air of 6.0 rotations per second and a peak rotation rate of nearly 7 rotations or more, which is where the attempt comes far short.

The average rotation rate of this attempt is 5.3 rotations per second, well above what is typical for a triple Axel, but far short of what is needed for a quad Axel; in other words, not even close.

Breaking this down a little further, Hanyu's rotation rate is significantly greater on the first half of flight (takeoff to peak of the jump) and well over 6 rotations a second, but much slower on the second half.  So the problem is not a lack of torque and initial angular momentum on the takeoff.  Rather the problem is control of the moment of inertia in the air.  That is, the main flaw in this attempt is the air position that slows the rotation.

In this attempt, there is too much "light" between the legs, which are not perfectly straight and the elbows stick out too far with the arms not tight against the torso - with a look we refer to as "helicopter arms."  These three position defects increase the moment of inertia and slow the rotation rate.

Comparing Hanyu's air position to Nathan Chens' there is a significant difference in technique between the two.  Chen uses flat palms against the chest with forearms fully in contact with the torso.  Hanyu uses a fist into palm, in front of the sternum.  Hanyu's position leaves the elbows farther from the rotation axis than Chen and allows the elbows to more easily open outwards away from the rotation axis.  Chen's position is more stable and resistant to "helicopter arms" in the air.

Getting more takeoff angular momentum for this jump is probably not obtainable, so to get this jump to full rotation would require reducing the moment of inertia by 12% or more.  Whether Hanyu can improve the position enough to get there remain to be seen, but given how long he was worked on this jump and how far off the mark it still is dynamically, it seems unlikely.

The question we asked earlier in the season remains.  Does Hanyu want to be a three time Olympic Champion, or does he want to be the first skater who attempted a quad Axel at the Olympics and lost.

Copyright 2021 by George S. Rossano