The mid-1920s saw two major breakthroughs: one-piece metal propellers and ground adjustable propellers with blades that could be manually changed before flight for optimum pitch setting. Hamilton Standard acquired this technology from its predecessor, the Standard Steel Propeller Company, which worked directly with the propeller unit of the Army Air Service at McCook Field to improve propeller design. Ground-adjustable-pitch propellers, such as this artifact, provided revenue that kept Hamilton Standard going during the dark days of the Depression.
This aluminum propeller flew on an engine produced by the Velie Motors Corporation, Moline, IL, which started in the aircraft engine field with the Model M-5, type certificated in 1928. The engine was a close copy of the 1926 Detroit Aircraft Engine Corporation Aircat, and powered the Mono Aircraft Monocoupe 70, Monocoupe 113, and Monoprep 218. Velie Motors capitalized the Mono-Aircraft Corp., also of Moline, IL, and later evolved into the Lambert Engine and Machine Company.
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.