I am flying a Piper 28-336 Dakota. Based on this paper I was able to reproduce the take-off distances from the POH and incorporate the calculations directly in Excel. It can be seen that the effects of temperature and weight on the takeoff distances are not linear and can be approximated by (with no wind correction and based on the above paper)
$ReferenceDistance\times[(1-Altitude)/145442]^{5.2}\times(273.15+15)/(273.15+Temperature)]^{DensityRatio}$$\times(Weight/3000)^{WeightRatio}$
However for the landing distances it seems that the above formula does not work as the landing distance seems to be more "linear" than the takeoff distances.
Can anyone provide the precise equations to be used for computing the landing distances as a factor of altitude, weight, temperature and winds? Or references that include those equations?
