Posted by mike worrall on September 25, 2002 at 19:35:39:
In Reply to: Gear Ratio posted by Haji on September 20, 2002 at 05:05:09:
Dave Gerr wrote in a nifty artice in the Feb '01 edition of Sail (magazine) on this subject, which included a cool nomograph cosidering RPM / Prop Diameter / Power. Simply place a straight edge between any two know quantities, and you get the value of the third. Gerr admits that one will run into "real world limitations" in that you'll find that, to achieve the "ideal shaft speed" you'll neeed a gear reduction of greater than 3:1, which you'll not likely find. His solution: consider changing the prop diameter (but don't foget the req'd tip clearance)! The March '01 edition concluded the series (by Gerr) on propellers with a discussion on screws - folding, fixed, # of blades. Good stuff.