Selecting a motor for the disc thrower will need to account for: The necessary output speed of the wheel launcher The torque applied to the wheel. System: The disc weighs 0.18kg (http://www.andymark.com/FIRST-Choice-p/fc13-141.htm) Field = 50' max Speed of Launcher:Our team did several trials for how fast a disc must be thrown to not drop over 50feet (~15.4meters) to cross the game field. The trials results ranged from 1.2seconds to 1.5seconds. We use the 1.2seconds as the time to cover 15.4meters. This provides a linear speed of 15.4m/1.2s = 12.82m/sA wheel travels it's circumference(pi*diameter) every revolution (distance/rev). This provides Pi*Diameter/Revolution Our team examined 6", 8" and 12" wheels (39.354"/meter) Now determine how fast the launcher must spin to achieve a linear speed of >12.82m/s
Then convert inches to meters for units
Then use the linear speed of 12.82m/s to determine the rev/sec needed for each diameter wheel
Then, for compatibility with motor units convert the rev/sec to rev/minutes
If there is any gear ratio between the motor output and the launching wheel then that must also be included in the rpm to the motor. The actual excel sheet is a little easier to see the diameter linked to the output:
The spinning objects are measured several ways. Cycles per second = Hertz Radians per second = 2*pi*Hertz Revolutions per second = RPS = Hertz Revolutions per minute = RPM = Hertz*60 Motors are usually rated in Revolutions per minute (RPM)The units for linear speed is meters/ second |

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