1# Use this file to tweak the model parameters for engines 2# All force values are in kN 3 4# The x-value where the two curves intersect should match 5# the maximum speed for the real engine 6 7# Stationary tractive effort 8ps(x) = 34.7 9 10# Knee point where tractive effort tails off (m/s) 11knee = 10.0 12 13# Continuous tractive effort 14pc(x) = (ps(0) * knee)/x 15 16p(x) = x < knee ? ps(x) : pc(x) 17 18# Resistance 19# There should be at least an order of magnitude difference a << b << c 20a = 4 21b = 0.05 22c = 0.006 23q(x) = a + b*x + c*x*x 24 25set xrange [0:100] 26set yrange [0:50] 27set xlabel "Velocity (m/s)" 28set ylabel "Force (kN)" 29 30plot p(x) title 'Tractive effort', \ 31 q(x) title 'Resistance'