Needed Cylinder Math

[Lawry Goldstein]

Hi there, we did the following math and I would like to check it over because it seems a bit fishy:

We are using:
21.5" 1" PVC tube where the axis of rotation is about 1.5" from one end we believe that it is about 1 lbs total. On that axle there will be a sprocket which we currently have at 5" diameter.

We plan to have the piston connected by chain to the sprocket to make a 90 degree rotation.

What size sprocket/piston do we need, what pressure?

We calculated that we would need a 1.5" bore piston with a 4 inch stoke at 40 PSI to have a balance (No safety factor at 40psi, up to 60psi would be our safety here), is this all correct?

[thefro526]

Math sounds about right. The only thing that sounds a bit off might be the pressure but if you get a regulator you can regulate it down to whatever works the best. I'm assuming that the 4 inch throw is from a 5inch sprockets circumference of about 16 inches of that and a fourth of that is 4 inches. if thats so then thats all the throw you need.