Originally Posted by
skwinty
The calibration of an altimeter is of the form
z=cT log(Po/P)
There is no v for velocity in the equation.
There isn't because your formula is for calibrating a
stationary altimeter in the lab (e.g., with a pneumatic test set)..
A static port on an aircraft is basically just a small hole in the fuselage, connected to the altimeter by a tube.
Because of the airflow around the fuselage, the pressure at the location of that little hole is
not the same as the free-stream static pressure at a sufficient distance from the plane.
Even if a lot of care is taken to find a location where the pressure is 'nearly' the same, you still need an f(v) or f(M) correction term, generally obtained from wind tunnel and flight tests, in the form of a graph (or 'look-up table') of a correction term k against v or M.
It's that graph that
gravity32 is after.
CJ