eh... poephoofd, 1st thing, there are dutch ppl on this site so i'll give away that your name mean the same as "shithead" and your signature is "i want to go to florida, fun, heh, you don't know what this says"
back to topic, if you want to make a turn which is a 10meter 1/4 circle, the given lenght should be the lenght of the control points
as for the other tabs
0g banking: gives you the perfect banking, all you have to put in are speed, vertical Gs and lateral Gs
Station lenght: give the number of seat rows and the calc will determine how long the station should be to provide the right number of gates
Lim lenght: give in the final speed and acceraltion Gs and the calc gives you the ideal lenght of your launch section
the converter is for feet/meter and meter/feet conversion
P.S. if you want additel help in dutch, add me on msn