Originally Posted by LeeD
60 degrees is waaaay high an angle.
Closer to 35 is reality.
If you tossed the racket on edge and it landed before the back fence, you have a moderate serve speed.
Now if you released the racket with the face like hitting a flat serve, you have a great serve speed.
It really depends what part of the upward swing (path) you are talking about. As the racket head moves out of the "backscratch" loop it is moving nearly vertical (90 degrees). In looking at the Sampras swing path (in the photo above), we see that shortly after the loop we still see a very steep angle -- much greater than 60 degrees. For much of the upward swing the racket tip moves upward at an angle greater than 45 degrees -- it appears to be close to 60 degrees just after the big L position.
Very near contact, the racket path angle starts to diminish quite a bit -- nearly horizontal at contact. At Sampras' contact, the racket face appears to be a bit closed but it seems that the tip is still moving upward slightly. From this view of Sampras' swing path we cannot give the "throwing angle" a single number. The path angle changes quite a bit from the beginning of the upward to the contact point.
The OP is undoubtedly releasing the racket handle a bit before where the actual contact point would be. Note that Will Hamilton had a video on his FYB site where he suggested throwing the racket upward at a steep angle in order to facilitate a proper racket head drop (from the trophy). With his throws at low angles (much less than 45 degrees), very little racket head drop was employed. An good "racket throwing" angle would start off very steep and finish off shallow. Where you actually let go (along with other factors, perhaps) would determine the launch angle.