This article is from Skagit Aero's Blog Skagit Aero Museum, who has kindly granted permission to re-publish on

Some times its the parts that are almost as much fun to find as the airplanes themselves. This was recently the case when Jim was crawling around a barn belonging to a friend of the museum down the river. Amidst the large number of airplane fuselages and other pieces, was a long wooden box with a brand new propeller inside. Jim was able to acquire the propeller for the museum and we look forward to it filling in nicely among the vintage parts we have already.

Best of all it wasn’t your average wooden propeller, it’s a constant speed propeller delivered in 1944 made by the Engineering and Research Corporation (ERCO) of Riverdale, Maryland. Beginning shortly before the United States entered World War II and lasting throughout the war, aluminum was in short supply for manufacturers of general aviation aircraft and even the military trainer fleet. So propeller manufacturers built wooden propellers to substitute for the metal ground adjustable and constant speed props. Of course wooden propellers were nothing new, but for these more advanced props, metal had been the norm.

The ERCO propeller uses a 2B20 hub and was used on airplanes such as the Stearman and Stinson V-77. The blades were carved from a laminated, compressed, impregnated block of wood and were stamped with the “Compreg” label. Brass covered the tips and leading edge like many wooden propellers. A steel alloy ferrule was attached permanently to the blade and allowed the connection between the wooden blade with the Standard Hamilton controllable pitch hub.

The shipping box included a box of parts as well as the log book and other historical items.