Calculate Torque Needed for 100lb 11ft Propellor @ 1RPM

[Metahedron]

Good day!
How do I calculate how much torque I need in a motor for my project?

I must rotate a 100lb propellor, which is 11 ft in diameter, at 1 rpm .

 

[berkeman]

Welcome to the PF.

You only need torque to spin up the propeller to speed, and to overcome bearing friction. Does the apparatus exist already? If so, you could just make hand measurements of the torque required, and then use that information to size your motor. Will you be using speed reduction gearing to get that slow rotation rate?

 

[Metahedron]

I do not have the apparatus presently, just the designs. I do plan to use speed reductions gears, but I was also hoping to use a dc motor with pwm control. Is there a most ideal technique for this? It has to be able to run non stop for two weeks.

 

[berkeman]

When you start it up, can you use a hand-assist to get it going? Then you basically only have to overcome friction of the bearings. Is the propeller vertical or horizontal? What are you using for bearings?

 

[berkeman]

BTW, how are you planning on coupling the geared-down motor shaft to the propeller? If you make that coupling with a Freewheel coupler, then you could spin up the propeller by hand to a little over 1rpm, and let bearing friction slow it down to where the motor takes over through the Freewheel coupler...

https://en.wikipedia.org/wiki/Freewheel