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Japan's Imperial Navy flag

Japan's Aichi S1A Denko (bolt of lightning) night fighter, Navy Experimental 18-Shi Night Fighter


  • Aichi S1A Denko night fighter



The Aichi S1A was to be the replacement for the Nakajima J1N1-S that were being used as night fighters.

The Imperial Japanese Navy issued the 18-Shi specification for a night fighter. It was to have the following specifications:

  • Speed at 29,530' / 9,000 m: 426 mph / 370 knots
  • Endurance: Five hours
  • Climb to 19,685' / 6,000 m: Eight minutes
  • Armament: Two 30 mm cannons
  • Air borne radar

Air brakes were installed in the wing and the center of the fuselage to help in not overtaking a bomber in flight.

The radar was installed in the nose.


The pilot was located in a cockpit over the wing's leading edge and the radar operator in a cockpit placed over the trailing edge. The radio operator also remotely controlled the guns in the dorsal turret.


The first prototype, which was 70% complete, was destroyed in an air raid and the second prototype, 90% complete, was destroyed in another.


None were produced.


  • Navy Experimental 18-Shi Night Fighter, Aichi S1A1:


Type Night Fighter
Crew Pilot, radio-operator
Engine (Type) 2: Nakajima NK9K-S Homare 22
Cylinders Radial 18
Cooling Air
Net HP 2,000 each
Propeller blades 4 metal constant speed
Span 57' 4 31/32"
17.5 m
Length 49' 6.5"
15.1 m
Height 15' 1.5"
4.61 m
Wing area 505.902 sq ft
47 sq m
Empty 16,138 lb
7,320 kg
Load - Normal 22,443 lb
10,180 kg
Load - Maximum 25,375 lb
11,510 kg
Speed at 26,245' / 8,000 m 366 mph
318 knots
Speed - Cruising at 13,125' / 4,000 m 276 mph
240 knots
Climb to 29,530' / 9,000 m 14 minutes 45 seconds
Service Ceiling 39,370'
12,000 m
Range 1,054 statute miles
916 nautical miles
Range - Maximum 1,580 statute miles
1,373 nautical miles
Nose 2: 30 mm Type 5 cannon
2: 20 mm Type 99 Model 2
Turret - Dorsal 2: 20 mm Type 99 Model 2
Bombs 551 lb
250 kg


  1. Japanese Aircraft of the Pacific War, René J Francillon, 1970
20th Century American Military History Crucial Site