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Aichi S1A Denko (Bolt of Lightning)

Imperial Japan (1946)
Picture of Aichi S1A Denko (Bolt of Lightning) Twin-Engine Night-Fighter Aircraft Proposal

The twin-seat, twin-engine Aichi S1A Denko was intended as a successor to the Nakajima J1N1 Gekkou line in the night-fighter role for Japan during World War 2.


Detailing the development and operational history of the Aichi S1A Denko (Bolt of Lightning) Twin-Engine Night-Fighter Aircraft Proposal.  Entry last updated on 6/21/2018. Authored by Staff Writer. Content ©www.MilitaryFactory.com

The Aichi S1A "Denko" was in development with the Empire of Japan during World War 2 (1939-1945) as a successor to the Nakajima J1N1 "Gekkou" - or "Gekko". The Gekko proved itself since its introduction in May of 1941 as a very capable twin-engined heavy fighter. It saw service as a long-ranged reconnaissance platform but, more importantly, as a night fighter fitted with radar and obliquely-angled (30-degrees) 20mm cannons designed to strike at the vulnerable bellies of Allied bombers.

As good as the Gekko was, the arrival of the American Boeing B-29 "Superfortress" from May of 1944 on over Japanese territories across the Pacific Theater began to outclass the early-war Nakajima design - it lacked the high-altitude performance and a more capable radar fit needed to contend with the new threat. As such thought was given to a new twin-engined heavy type with modern qualities and exceptional capabilities and this charge fell to Aichi as other, more prominent, aircraft-builders of the war were tied to other production commitments for the Empire.

The resulting design became the "S1A" carrying a crew of two and outfitted with the required mission equipment for the night-hunter role. Dimensions included an overall length of 15 meters, a wingspan of 17.5 meters, and a height of 4.6 meters. Structurally, the S1A1 was to become Japan's largest fighter of the war. Empty weight was 7,320 kg against a Maximum Take-Off Weight (MTOW) of 11,510 kg. Power was from 2 x Nakajima NK9K-S air-cooled, twin-row 18-cylinder radial piston engines developing 2,000 horsepower each and driving four-bladed propeller units.

The aircraft's general configuration was typical of Japanese heavy fighter entries seen during World War 2 . It utilized a central fuselage containing the crew of two, avionics, fuel stores, and vital mission equipment. The cockpit was seated well-forward of midships and aft of a short nosecone assembly. The nose section held the standard fixed, forward-facing armament. At midships was a framed observation dome seated ahead of a turret emplacement. The tail unit relied on a single vertical fin with low-mounted horizontal planes along the aft fuselage sides. The wing mainplanes were ahead of midships and each held an underslung engine nacelles - the pilot being given unobstructed views of both installations. The mainplanes themselves were straight in their general design with clipped wingtips. The undercarriage was a typical "tail dragger" arrangement.

Performance for the S1A in prototype form included a maximum speed of 360 miles per hour, a cruising speed of 275 miles per hour, a range out to 1,555 miles (ferry), and a service ceiling of 39,370 feet.

Armament centered on 2 x 30mm Type 5 cannons and 2 x Type 99 Model 1 cannons fitted to the nose section for considerable forward-facing firepower. The aforementioned turret emplacement along the fuselage spine fitted 2 x 20mm Type 99 Model 2 cannons offering a trainable weapon's position.

The S1A was a promising design by mid-war standards but its projected weight was beginning to suffer as more and more mission equipment was added. Additionally, the intended Nakajima radials were not presenting the required power that IJN authorities sought so thought was given to fielding S1A1 production models with Mitsubishi engines instead. On December 7th, 1944, there was also a major earthquake off the coast of Japan - the "Tonankai Earthquake" (Magnitude 8.1) - which resulted in the two ordered prototypes being heavily damaged along with their production facilities. Allied bombing raids in June and July of 1945 ended all hope for the aircraft as both prototypes were destroyed and the work was taken up again.

Japan surrendered to the Allies during August of 1945 bringing about a complete end to World War 2.

Any available statistics for the Aichi S1A Denko (Bolt of Lightning) Twin-Engine Night-Fighter Aircraft Proposal are showcased in the areas immediately below. Categories include basic specifications covering country-of-origin, operational status, manufacture(s) and total quantitative production. Other qualities showcased are related to structural values (namely dimensions), installed power and standard day performance figures, installed or proposed armament and mission equipment (if any), global users (from A-to-Z) and series model variants (if any).






Our Data Modules allow for quick visual reference when comparing a single entry against contemporary designs. Areas covered include general ratings, speed assessments, and relative ranges based on distances between major cities.

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Relative Maximum Speed Rating
Hi: 400mph
Lo: 200mph
    This entry's maximum listed speed (360mph).

    Graph average of 300 miles-per-hour.
City-to-City Ranges
NYC
 
  LON
LON
 
  PAR
PAR
 
  BER
BER
 
  MOS
MOS
 
  TOK
TOK
 
  SYD
SYD
 
  LAX
LAX
 
  NYC
Graph showcases the Aichi S1A Denko (Bolt of Lightning)'s operational range (on internal fuel) when compared to distances between major cities.
Aviation Era
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Pie graph section
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Pie graph section
Useful in showcasing the era cross-over of particular aircraft/aerospace designs.
Unit Production Comparison
Comm. Market HI*: 44,000 units
Military Market HI**: 36,183 units
0
0


  * Commercial Market High belongs to Cessna 172.

  ** Military Market High belongs to Ilyushin Il-2.


Altitude Visualization
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  Compare this entry against other aircraft using our Comparison Tool  
National Flag Graphic
Origin: Imperial Japan
Year: 1946
Type: Twin-Engine Night-Fighter Aircraft Proposal
Manufacturer(s): Aichi Kokuki KK - Imperial Japan
Production: 0
Status: Cancelled
Global Operators:
Imperial Japan (cancelled)
Historical Commitments / Honors:

Military lapel ribbon for Operation Allied Force
Military lapel ribbon for the Arab-Israeli War
Military lapel ribbon for the Battle of Britain
Military lapel ribbon for the Battle of Midway
Military lapel ribbon for the Berlin Airlift
Military lapel ribbon for the Chaco War
Military lapel ribbon for the Cold War
Military lapel ribbon for the Cuban Missile Crisis
Military lapel ribbon for the Falklands War
Military lapel ribbon for the French-Indochina War
Military lapel ribbon for the Golden Age of Flight
Military lapel ribbon for the 1991 Gulf War
Military lapel ribbon for the Indo-Pak Wars
Military lapel ribbon for the Iran-Iraq War
Military lapel ribbon for the Korean War
Military lapel ribbon for the 1982 Lebanon War
Military lapel ribbon for the Malayan Emergency
Military lapel ribbon for the attack on Pearl Harbor
Military lapel ribbon for the Six Day War
Military lapel ribbon for the Soviet-Afghan War
Military lapel ribbon for the Spanish Civil War
Military lapel ribbon for the Suez Crisis
Military lapel ribbon for the Vietnam War
Military lapel ribbon for Warsaw Pact of the Cold War-era
Military lapel ribbon for the WASP (WW2)
Military lapel ribbon for the World War 1
Military lapel ribbon for the World War 2
Military lapel ribbon for the Yom Kippur
* Ribbons not necessarily indicative of actual historical campaign ribbons. Ribbons are clickable to their respective campaigns/operations.
Measurements and Weights icon
Structural - Crew, Dimensions, and Weights:
Unless otherwise noted the presented statistics below pertain to the Aichi S1A Denko (Bolt of Lightning) model. Common measurements, and their respective conversions, are shown when possible.

Operational
CREW


Personnel
2


Dimension
LENGTH


Feet
49.54 ft


Meters
15.1 m


Dimension
WIDTH


Feet
57.41 ft


Meters
17.5 m


Dimension
HEIGHT


Feet
15.09 ft


Meters
4.6 m


Weight
EMPTY


Pounds
16,138 lb


Kilograms
7,320 kg


Weight
LOADED


Pounds
25,375 lb


Kilograms
11,510 kg

Engine icon
Installed Power - Standard Day Performance:
2 x Nakajima NK9K-S engines developing 2,000 horsepower each.

Performance
SPEED


Miles-per-Hour
360 mph


Kilometers-per-Hour
580 kph


Knots
313 kts


Performance
RANGE


Miles
1,553 mi


Kilometers
2,500 km


Nautical Miles
1,350 nm


Performance
CEILING


Feet
39,370 ft


Meters
12,000 m


Miles
7.46 mi

Supported Weapon Systems:

Graphical image of an aircrat automatic cannon
Armament - Hardpoints (0):

PROPOSED:
2 x 30mm Type 5 cannons in fixed, forward-firing mountings on fuselage.
2 x 20mm Type 99 Model 1 cannons in fixed, forward-firing mountings on fuselage.
2 x 20mm Type 99 Model 2 cannons in dorsal-mounted turret.
Variants: Series Model Variants
• S1A "Denko" - Base Series Designation
• S1A-1 - Assumed production model designation; none built.