Gasuden “Kōken-ki” world-record non-stop flight, 1938.

Gasuden Kōken, c. 1937-38. The Gasuden Kōken (also known as the Kōken-ki, trans. ‘experimental aircraft’) was a Japanese long-range research aircraft of the 1930s. It was built by the Tokyo Gas and Electric Industry (‘Gasuden’) to break the world record for longest non-stop flight, setting a world record (11,651.011 km/7,240 mi) in March 1938 around a 249-mile “closed course” ringing Mt. Fuji, Japan’s sacred mountain.

“The Gasuden Koken, aka Kōken-ki, a 1930s Japanese long-range research aircraft, was designed by the the Tokyo Imperial University Aeronautical Research Institute and built by the Tokyo Gas and Electric Industry (also known as ‘Gasuden’) for the purpose of setting a closed-circuit, non-stop long-distance world record.

“In 1931, the Aeronautical Research Institute began research into the aircraft, with funding provided by the Japanese Diet. The initial design was finished in August 1934. Despite having little funding and a history of only building small quantities of wooden light aircraft, Gasuden was chosen to develop the aircraft, a single-engined low-wing cantilever monoplane with retractable undercarriage.

“The Gasuden Kōken-ki was made entirely of aluminum but had outer wings and control surfaces covered with Egyptian cotton fabric, protected by eleven coats of red paint giving the airplane its name: ‘Crimson Wing’. Although a diesel engine was originally planned to power the aircraft, that proved impractical, so a modified version of the German BMW VIII gasoline-fueled engine, license-built by Kawasaki, capable of producing 715 horsepower, was selected in the end.

“The Kōken-ki took a long time to build because of sporadic parliamentary funding, and wasn’t completed until March 1937. Major Fujita Yuzo of the Imperial Japanese Army piloted the first flight of the ‘Crimson Wing’ on May 25, 1937. The first two attempts to break the record, on November 13, 1937, and again on May 10, 1938, were unsuccessful due to undercarriage issues and an autopilot failure respectively.

“Then, on May 15, 1938, at 04:55, the Kōken-ki took off for a third time from Kisarazu, Chiba, flying a four-sided course of 402 kilometers (249 mi).

“Two days, 14 hours, 26 minutes later, ‘Crimson Wing’ landed at Kisarazu having flown a total distance of 11,651.011 km (7,239 mi), setting a new world closed-circuit non-stop distance record … and with 500 liters (132 gallons) of fuel still remaining in its fuel tanks. The record stood until August 1939, when it was broken by an Italian Savoia-Marchetti SM.82 that flew 12,936 km.

“The Kōken-ki was subsequently only used for test flights on rare occasions, with its last flight taking place in 1939. It survived the Pacific War only to be destroyed [for scrap] at the end of the war. The Misawa Aviation & Science Museum in Misawa, Aomori Prefecture, has a full-scale model of the Kōken-ki on display today.”

– Airways, by Hellwing Villamizar, 2022