Fly velocity as a function of loop speed

Jim....

Perhaps a more simplified way of looking at the speed of the fly during the 
cast as twice the forward speed of the loop is this:

Consider the fact that the fly must travel exactly twice the distance of 
that of the loop in the direction of the cast.

It does this in the same length of time.

Hence the necessity for the fly to travel at twice the speed of the loop in 
order to arrive at the same place at the same time (the end of the cast).

                                        Gordy