jaydeehess
Penultimate Amazing
Then why did R. Mackey use a constant total velocity of 781 fps?
Because it approximates the situation sufficiently. In a shallow desent the velocity along the long axis of the aircraft will not differ greatly from the ground speed.
In a 45 degree steep dive the ground speed would be 70% of the velocity along the long axis of the aircraft.
In a 4.5 degree 'dive' (which I use for illustrative purposes. 4.5 degrees being 1/10 of 45 degrees) the ground speed would be 99.7% of the velocity along the long axis of the aircraft.
(the following includes more significant digits than would be proper but I include them for illustrative purposes)
So 781 f/s X 0.997 = 778.6 f/s
As the plane pulled out of the dive the angle with the ground decreases and the difference between ground speed and longitudinal velocity becomes even closer.
For a 3 degree 'dive' it is 99.86% (779.9 f/s)
at 1 degree 'dive' it is 99.98% (780.8 f/s)
I do note that the equation that PfT used
a=v2/r
is the calculation of centripetal acceleration in circular motion.
I thought this was to be a parabolic trajectory! (r is not a constant)
I still do not see an answer as to how the radius of the circle was determined either.
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