Excel Worksheet and Chart

The numbers you really want are on the Type spec for the aircraft. All
of these can be found on the FAA's website. That takes care of the
W&B issues.

For the TO&Landing numbers, you need to "optimum" numbers from the
manufacturer. They should be in the POH for the aircraft. Additionally
the "fudge factors" for various factors (dry grass, wet gradd, slope,
temp, runway length, etc) are either in the POH or supplemental
documentation. If you can't easily find it, check various web
sites such as AOPA Safety Foundation and FAA.

For example, the ASA lists these multiply factors for both the
Cherokees (and Warriors) and the Cessna 172:



Take off

Variation Factor
10% increase in aircraft weight 1.2
Each 1000 ft increase altitude 1.1
Each +10 deg C increase in temp 1.1
Dry, short grass 1.2
Dry, long grass 1.25
Wet, short grass 1.25
Wet, long grass 1.3

Each 2% uphill slope 1.1
Tailwind that's more than 10% of
your lift-off speed 1.2

Landing

Variation Factor
10% increase in aircraft weight 1.1
Each 1000 ft increase altitude 1.05
Each +10 deg C increase in temp 1.05
Dry, short grass 1.2
Dry, long grass 1.3
Wet, short grass 1.3
Wet, long grass 1.4

Each 2% uphill slope 1.2
Tailwind that's more than 10% of
your lift-off speed 1.2

Consider a Cherokee 180 at altitude of 1500 ft on a 25C day,
flat concrete, no tailwind, weigh of 1700 pounds. Then from the Piper
tables the TO distance is 2200 feet -- on a good day, with a brand new
aircraft and a test pilot. Personally, I'd plan for 3000 or more!