The variable-pitch propeller advanced safety and efficiency of aircraft by providing a "gear shift of the air." Its dramatic improvement in performance won Frank Caldwell and Hamilton Standard the 1933 Collier Trophy, bestowed by President Roosevelt for the National Aeronautic Association at the White House. This artifact is a specimen of that technology, and was the first of its type to achieve over 2500 hours of flying service.
The propeller flew on a United Air Lines Boeing 247 aircraft, which is generally recognized as the first civil aircraft to embrace features providing economic advantage such as all-metal construction, fully cantilevered wing, wing flaps, and retractable landing gear. However, with fixed pitch propellers, the early version of the aircraft had difficulty at high-altitude. With this controllable, two-position propeller beginning in June 1933, climb rate grew twenty-two percent, take-off distance improved twenty percent, and cruising speed increased 5.5 percent to 274 km/hr (171 mph).
This object is not on display at the National Air and Space Museum. It is either on loan or in storage.