Spin Up Time Calculator- Amateur
- Adam Wrigley
Last updated - June 2006
DISCLAIMER: Combat robotics is a dangerous sport by it's nature. Extreme caution should be taken when performing any operation explained on this site. Any injury or death resulting from the use of these pages is the sole responsibility of the user and not totalinsanity.net. By undertaking the construction of a combat robot you assume all responsibility for your actions. When building a combat robot, always make sure you are, or are with, a responsible adult.
Build Responsibly.
This calculator will help you easily calculate the spin up time for your weapon system.
To find the mass moment of inertia of your weapon, click here.
Spinner Calculator(requires javascript)
If you need help converting units, download this program: ConvertAlso of note is that this calculator does not take into account your choice of batteries. This assumes that your batteries will be able to source the correct voltage and amperage without any problems. Real life batteries will have a "voltage drop" when a lot of amperage is pulled from them. So, your actual spin up time will be somewhat longer than the theoretical time displayed here.
A little about the theory(not necessary to use the calculator, but useful if you want to know how the calculator works):
The power output of a permanent magnet electric motor is the product of the Torque, and the RPM, as in any rotational power device. Unlike gas engines, electric motors will produce their maximum Torque at 0 RPM. They will produce their maximum RPM at 0 Torque. The pattern of RPM and Torque between these two points is linear. Using this relationship of RPM and Torque it is possible, though very "mathy," to create a 1st order differential equation. This equation does not need to be solved, and the time constant can simply be taken from the equation (when the equation is put into time constant form) and used to figure out spinup time.
The full derivation of this calculator will be covered in another tutorial soon.
