Helix, cylinder, distance traveled?

Good morning, my name is Steve and I'm looking for some help solving what I thought was a simple problem!! A little heads up, I'm just a farm boy with a high school education so I'm not as familiar with terms and formulas as I would like to be. Any help would be greatly appreciated(Happy).

Problem: If I build a 24 inch cylinder 12ft long with a helix wrapped around it at 20 degrees, how far will that cylinder move forward or backward in "1" revolution? This is a giant screw moving on the ground, need to know this info to determine RPMS required to move this machine at 8-10 mph. Also will be used to determine torque and motor requirements for hydraulic systems.

Thank you very much! Steve

Re: Helix, cylinder, distance traveled?

I take it that "24 inch cylinder" means diameter 24 inches and so circumference $24\pi$ or approximately 75.4 inches. In one revolution, it will have turned 75.5 inches and so have extended forwary by x= 75.5(tan 20 degree)= 27.5 inches.