Hinged-Blade Research Propeller This 10-foot experimental propeller was ground-tested at McCook Field for the U.S. Navy. Built by Paragon Engineers Inc., it was designed with hinged blades to permit it to adapt to changes in air pressure.
Micarta Controllable Pitch Propeller This 9-foot propeller has "Bakelite Micarta" blades counterbalanced to permit the pitch to be changed in flight. Designed by McCook Field engineers for testing with the Wright-built 180-hp Hispana-Suiza engine, it was tested in 1922 at McCook Field but was not successful.
Olmstead High Efficiency Propeller This unusual 9-foot propeller was designed in 1918 by Olmstead Laboratories and tested at McCook Field. It was intended for possible use on the Loening M-8 aircraft before the Air Service decided not to order the M-8 into production.
Curtiss Reed Propeller Produced in the 1920s, this 10-foot aluminum-alloy propeller was unique because its blades were mechanically twisted during manufacture to provide the necessary angle for thrust. PW-8 aircraft with Curtiss D-12 engines and XO-1 aircraft with Liberty 12 engines used this kind of propeller.