Mac, I too, found your table interesting. Seems to me, this ratio gives an indication of how much the propeller is "slipping". In other words, if there were a direct coupling, as in a car for example, this ratio would remain constant (at least in a given gear). The fact that it varies shows the amount of slippage which, I assume, is an indication of "how hard the prop is working". Not very scientific, but seems intuitively correct to me. Henry aboard Sno' Dog In a message dated 8/2/2006 6:48:43 A.M. Eastern Daylight Time, k2gkk@hotmail.com writes: Hi, Bob. I have no idea as to why the performance of Henry Clew's PDQ 34 seems to be so linear. I am just mathematically inclined and I noticed an apparent linearity. I just used a calculator to check out the extent of linearity and decided to share it with the group. I would say that the linearity indicates a happy marriage of design elements, whether intentional or accidental. In any event, I would say that the linearity in 'Sno Dog's performance is highly desirable. Mac in Oklahoma City