Excel worksheet for some of my speed runs

[kulangflow]

Originally posted by MetalMan
If you don't have Excel, there is a program that you can use to figure out speed:
http://www.waits.net/public/rcgears/
It's the one that I use.

I've compared this calculator to my actual GPS tested results and have found something to be quite off by an average of 9.4 mph.

For example, my 8S powered Rusty at 22/84 "should" hit 53.4 mph on 10 cells at 1.05V, but "actually" only hit 40.5 mph ... a big difference of 12.9 mph.

Does this mean that I'm doing something wrong (calculations or actual testing), or that the calculator doesn't include real life items like weight and wind resistance?