Simple Pitch Gage

摘要

When you look at a rubber powered propeller, everything you see is curved or twisted. Nothing is flat, straight, or easy to put a scale on. But surprisingly, that confusing twist in the blade is the thing that produces an important propeller dimension that is easy to measure: the Pitch. A propeller's pitch can be thought of as "The distance it screws itself forward in one revolution" (like the pitch of a machine screw). And it has been found that a uniform pitch over the whole blade is a very efficient configuration, so most propeller designs are aimed at constant pitch. That has another advantage: a propeller can be described with just two numbers, Pitch and Diameter.