Collection Item Summary:
Before World War II Japan adapted and modified foreign variable-pitch designs for its military and naval aircraft. The two primary manufacturers were the Propeller Division of Sumitomo Metal Industries, and the musical instrument manufacturer Nippon Gakki Company (the modern day Yamaha Corporation). This is a World War II artifact produced by Sumitomo, which began manufacturing propellers in 1925, and acquired a license for both the Hamilton Standard constant-speed counterweight propeller and VDM products in the late 1930s as Japan continued its military expansion into China.
By July 1944, Sumitomo operated four manufacturing plants producing 5,247 propellers a month under the direction of long-time general manager Osamu Sugimoto, an aeronautical engineer educated at MIT. With a majority being the Hamilton Standard type, Sumitomo produced 66 percent, or 89,885, of all propellers for Japan’s aerial war effort while Nippon Gakki produced 46,304, or 34 percent to account for a total of 136,189 propellers.