Google found several "aviation Koch chart" links including
this one
http://wind-drifter.com/technical/technical.htm scroll
down the page. They have some calculators listed, but the
Koch Chart is just the graph. But any high school math
teacher should be able to walk you through the solution of
the algebra problem to find the system of equations.





"Peter Duniho" wrote in
message ...
| "abripl" wrote in message
|
ups.com...
| Does anybody have the Koch Chart formula (equation)? Or
know where to
| find it?
|
| I don't think there is an actual equation that works
generally. As an
| obvious counter-proof to the idea that there is one,
consider that density
| altitude affects airplanes with normally aspirated engines
differently from
| those with turbocharged engines. The same Koch chart
would not work for
| both types of airplanes.
|
| I haven't done a lot of research on the origin of the Koch
chart, but I
| believe that it's to be used as a general guideline, not
as a precise
| determination of how airplane performance is affected by
density altitude.
|
| If you do want to implement the Koch chart mathematically
somehow, I'd
| suggest that your best bet (in terms of ease of
implementation) would be to
| manually read off a range of pressure altitude and
temperature combinations
| to create tables giving the performance adjustment, and
then interpolate
| between the values for specific input of pressure altitude
and temperature.
|
| You could more accurately describe a Koch chart
mathematically by actually
| reverse engineering it (the scales on the middle portion
of the chart appear
| to be logarithmic and exponential for the takeoff distance
and climb rate
| reduction, respectively, so you simply need to measure the
scales and
| determine the base and power for those functions, and the
pressure altitude
| and temperature graphs appear to be linear), but that may
be more trouble
| than it's worth. Given that the chart isn't a precise way
to determine the
| performance change anyway, you may find it's overkill to
analyze the chart
| that way.
|
| Pete
|
|