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Old 02-05-2013, 08:39 AM   #14
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Join Date: Jan 2006
Location: Vermont
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Originally Posted by Bob Gardner View Post
Ah Yes! Well spotted, Dave. So it's a USN prop made to the design of Dashwood Lang for a Liberty-engined Cutiss H 16 flying boat. All we need to know now is if it is half of a four-bladed prop or a two-bladed prop. For forumites who have joined recently, four bladed props were difficult to store and handle on board a warship, so they were made as two bladed props with a hub that was half the size of a normal hub and two were bolted together at right angles.

This hub should be around, say, ten inches deep from top to bottom, but if it's meant to be bolted to another prop, it will be about five inches thick. (These dimensions are illustrative not factual.)

With kind regards,

The published hub thickness is 7 1/4", but that will change slightly over time as the wood shrinks with drying.

Bob, I think there is a subtle difference between this presumably Paragon propeller and the Matthews Bros. prop, which uses an "L.P." drawing number and almost certainly is a Lang Propeller drawing. The Lang design has a sharp demarcation at the widest point ("diamond shaped") where the Paragon had a similar overall appearance but a more rounded appearance at its widest point at about the mid-blade position. I've seen several similar Paragon designs for several different aircraft.
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