What does "Denko" mean?

Short answer

"Denko" was the name of the Aichi S1A fighter and means "flash of light." The aircraft was meant to carry radar to counter B-29 raids over Japan, with two 30 mm Type 5 cannons and two 20 mm Type 99 Model 2 cannons. The 1945 air raids destroyed both its prototypes.

Published: November 1, 2026 · Updated: November 1, 2026 · Edited by Above Ten Thousand · Editorial policy

Boeing B-29 Superfortress

The Aichi S1A night fighter

"Denko" was the designation of the Aichi S1A and means "flash of light". The aircraft was to be fitted with radar to counter B-29 raids on Japan. Its planned armament comprised two 30 mm Type 5 cannon and two 20 mm Type 99 Model 2 cannon, plus another two 20 mm Type 99 Model 2 rearward-firing cannon housed in a remotely controlled turret.

Performance and design solutions

The required maximum speed was 426 mph at 29,530 ft. Among its particular features were drooping ailerons, able to work as supplementary landing flaps and as air brakes to stop the fighter from overshooting its target.

Two prototypes destroyed on the ground

On 9 June 1945 air raids struck Aichi Kokuki. Those bombings blew up the first S1A prototype and forced the second to be moved to the large Sadakazu factory at Gifu to complete its assembly; on 9 July, another air raid destroyed that second prototype.