FRC Blogged-Kit of Parts Drive System Option

[Ether]

Originally Posted by T^2

Keep in mind that JVN's "speed loss constant" comes after a "drivetrain efficiency" (i.e. losses from gearing), therefore the 81% number cannot be attributed to gearbox losses.

The Speed Loss Constant does not come "after" the drivetrain efficiency (at least not in the 2013 version). It is completely independent. See below:

The testing we did earlier this year found the overall speed loss from the theoretical free speed of the motors.

^^This is exactly what the "Speed Loss Constant" in the JVN spreadsheet is.

My conclusion now is the same as it was then: test your drivetrain instead of blowing smoke from your behind about the theoretical speed you think you'll get.

I love test data too.

But I still think it may be possible to develop a physics-based model that will reasonably predict overall drivetrain performance -- including not only top speed but also time to reach a desired speed, time to reach a desired distance, and accel, speed, distance, motor amps, motor volts, and Coulomb consumption versus time -- based on a priori estimates of a limited number of parameters .