The "data" embossed on hub would be (1st line), (Air Board?) Serial number; (2nd line) Aircraft Type; (3rd line), Appropriate engine (200 [HP] BHP); (4th line), Diameter (in metric, millimeters); (5th line), Pitch (in metric, millimetres). Believe that metric system was introduced by the RFC (or Royal Aircraft Factory?) at a very early date, possibly because so many of the very early aircraft (and aero engines) used by British services were either of French manufacture, or license-built from French manufacturers. So far as I know, the expression of technical data on British propellers lasted well into WW2. Anybody care to comment on my hypothesis, such as it is? Thank you in anticipation. Note that the "BHP" as listed on first line stood for "Beardmore-Halford-Pullinger" (designers and manufacturers) and NOT for "Brake Horse Power"!
Last edited by dduxbury310; 8th Feb 2024 at 19:58.
Reason: Additional information