This may sound odd, but I am working on formulas and tables so I can figure out what to bid mowing jobs at. In the formula I need a mean speed at which mowing is done at (in this case) in an open and flat environment with no obstacles. I have to bid an 18 acre park. So at what speed do you think you mow at? I'm guessing about 7 mph which would be about 80% speed on my Z-Trak. Am I close?