I'm sure you can combine equations as well as I, so ...


Variables: D=(density altitude) P=(pressure altitude)
T=(temperature in degrees celsius)


D = (145426 * (1- ((( 288.16 - P * .001981)

/288.16)^5.2563 / ((273.16 + T) / 288.16))^0.235))


APPROXIMATIONS:

For fixed pitch prop, increase sea level standard day takeoff distance 15%
for each 1000 foot increase in density altitude. Approximation good to 8000
feet density altitude

For constant speed prop, replace 15% with 13% in the above equation

For fixed pitch prop, decrease sea level standard day climb rate 7.5% for
each 1000 foot increase in density altitude.

For constant speed prop, replace 7.5% with 7% in the above equation.

(Equations and approximations from "Axioms of Flight", James Embree, Flight
Information Publications, St. Louis MO, 1984. ISBN 0-9601062-7-8)

Density altitude equation not independently verified. Use and report
results please.


Jim



"abripl" wrote in message
ups.com...
Does anybody have the Koch Chart formula (equation)? Or know where to
find it?
I have a chart copy but want the function.