Shawn. L. Turbo,
I'm not sure how people go about programming different dynomometers, but here are some basic formulas to start from:
Torque = (polar moment of inertia)*(angular acceleration)
The polar moment of inertia is a body's tendency not to rotate (an equivalent mass). Think of a bar bell with weights on the ends, then weights at the center. When the weights are at the ends it is more difficult to rotate.
The angular acceleration is obviously the change in angular velocity over time.
Let me describe a theoretical dyno. Consider a large, heavy barrel or roller. The heavy barrel has a certain calculated polar moment of inertia. A magnetic sensor on the barrel transmits a signal to a stationary sensor so that the rpm can be measured. A computer is used to calculate the time between pulses to calculate the rpm. When a truck's rear wheels are used to accelerate the heavy barrel, the computer will calculate shorter and shorter time intervals between index pulses from the rotation of the barrel. A simple algorithm can then be used to calculate angular acceleration, then multiplied by the known polar moment of inertia to obtain torque. The torque will be given for every point in time as the barrel was acclerated.
The only limitation of the above approach is that it assumes frictionless bearings, perfect adheasion from the tires to the barrel, etc. Therefore a modified formula could be:
Torque = (polar M. I)*(ang. acc) + bearing resistance(rpm) + ... + ...
it depends on the number of factors you feel are important. Bearing resistance is also a function of rpm of the barrel.
You can then calculate horsepower from the know torque at different rpms.
I know this is a simplified version, but it may get some of the principals across.
-Michael
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'00 2500 RAM, RegCab, 4x2, Cummins, 6-spd, Driftwood/Agate...