Is there an internet definition of the 'Waiter's Tray Error'
(WTE) on the serve that matches most TW forum usage of this term?
The 'Waiter's Tray' Error involves not having the desired 'edge on' racket orientation at some point in the serving sequence. At which point?
The effective 'edge on' racket orientation allows the arm-wrist-racket face to freely rotate as it approaches impact.
'Edge-On' racket face when arm becomes straight. One frame later at 240 fps the racket face has turned noticeably toward the ball impact orientation. Very rapid.
I have assumed that the 'Waiter's Tray Error' applies also just after the arm becomes straight
- in final position for the internal shoulder rotation and wrist joint motions that take the racket from about 90° to the arm to the beta angle
at impact (20-35°?) and provide 90%? of racket face velocity. With this view the WTE is transitory, dynamic because the elbow has just rapidly extended and other body joints are also moving. The desired 'edge on' or WTE probably only last a short time. But with WTE the racket really does not turn as rapidly as it does with the 'edge on' orientation. Does WTE also occur when the arm becomes straight?
Earlier in the service motion the racket face might be facing up in a similar way to WTE and that is OK, I guess?
These issues probably involve the sequence of supination and pronation as well as other joint motions. ??
Speculating - Maybe the 'Waiter Tray Error' occurs because the server has a misconception and believes that he has to swat-swing at the ball instead of using axial rotation of the arm. ? I had that misconception until last year too but have never had much tendency to do the WTE.