Oh and vag - I measure from heel off the ground to heel on the ground - when the heels raise the COM raises, if you pull up your toes you're on the air so I count that.
Yeah , you are wrong, it is just a good estimate and that happens by coincidence.
While you are still on the ground , you might be accelerating, keeping steady speed and then accelerating, maybe decelerating and then accelerating, the hangtime calculation formulas are not valid. The hangtime calculation formula is valid only after toes off , because then you have an initial velocity and gravity decelerating you. There is a type for that kind of movement and it is 100% accurate and the same for everyone on this world. Before that , each individual will have different acceleration patterns/times. What really happens is that including the acceleration phase in the hangtime caclulation inflates the calculated vert and that makes up for the error i mentioned in my previous post, so you get a number that is a good estimation, but that happens by coincidence. The 5'' correction i proposed is more reliable.
On another note , the hangtime calculation formula is accurate only for 100% vertical jumps. Adding angle to the jump introduces error to the calculated vert. But that error is equal the sinus of the takeoff angle, so for a 2 degrees angle your error will be ~0,03 ( 3% , 1.5 inches error every 50'' jump ).
Not my 2 cents , the only and undoubtable scientific truth.
