Is this an accurate curve for the ES44AC?
It is taken from
FREIGHT RAILROAD CAPACITY ALTERNATIVES IN THE PACIFIC NORTHWEST: AN ANALYSIS OF CLASS I COOPERATION IN THE COLUMBIA RIVER GORGE
by ZACHARY HOROWITZ
The above reference is a Master's Thesis in Civil Engineering. The figure is on page 40 and does reference GE.
kN is kilo-Newtons and kph is kilometers per hour. One Newton is the equivalent of 0.22 pounds, thus 800,000 Newtons is 179,848 pounds.
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Must be for export customers, since you wouldn't expect to see that stuff on the BNSF, UP, NS, CSX, CPR or CN as far as loco tonnage ratings/specifications.
I agree with HW, for the graph is based on metric, not standard, measurements.
I agree with HW, for the graph is based on metric, not standard, measurements.
I disagree there.The metric system is the International System of Units. That is the standard to which everything, including British Imperial units, are referenced to.
http://physics.nist.gov/cuu/Units/
http://physics.nist.gov/Pubs/SP330/sp330.pdf
Metric units are the standard globally, not the English units. I'm just the messenger, I don't make the rules.
I take it since the only complaint that the graph is in metric units that the data contained within it is correct?
Isn't starting T/E around 180,000lbs ...ish?
Isn't starting T/E around 180,000lbs ...ish?
That's what it is, 179,848 lbs which is the equivalent to 800,000 N.
Since there were not too many complaints about the curve, it seems that it is ok.
What is cool about the curve is that the horsepower can be easily calculated using the physical definition of horsepower.
http://www.physlink.com/education/askexperts/ae66.cfm
The graph is in Newtons and kilometers per hour. Thus the traction curve is in the units of Nm/s. Using the physical definition of the horsepower from the link above, 745.7 Nm/s = 1 horsepower.
To calculate the horsepower the bottom of the curve was used. Since the curve is drawn in a thick line there is some differences in the middle portion of the graph, but not so much at the two ends. The horsepower increases linearly up to 3874 hp at 13 kph. Horsepower continues to increase to the middle of the speed rage a peaks at 4001 hp at 60 kph. The hp then seems to fall slightly in the higher speed ranges.
This also works for British Imperial units. The units of a horsepower in British Imperial Units is lb ft/s. 550 lb ft/s is one horsepower from the link above. Thus at 10 kph the ES44AC travels at 9.11 ft/s and exerts a force of 179848 pounds. 9.11x179848 lbs = 1639034 lbs ft/s. Divide that by 550 to get hp and it comes to 2980 hp.
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