- Yes
- No
Note: This suggestion was imported from the old War Thunder forum. While the old suggestion was passed for consideration in the old forum, I’m required to repost this again due to the “clean slate” suggestion rule.
Hello, today I would like to suggest the addition of the Aichi S1A1 Denko (電光 - Thunderbolt). This plane is a rather enigmatic heavy fighter, night fighter, and interceptor with various special quirks not found in any other Japanese WW2 planes. Due to the several problems with the engines and unfortunate circumstances, however, none of the image of the complete prototype survives today.
A model of the S1A1, showing the layouts of the plane.
In the early years of the Pacific theatre of World War 2, the Imperial Japanese Navy doesn’t find a need to create a delicated night fighter. Starting from 1943, however, the Japanese main islands found itself under threats from occasional night bombing raids by the American’s B-17 Flying Fortress and B-24 Liberator bombers, and later from the B-29 Superfortress. The high command frantically tried to convert serveral existing aircraft to counter American bombers, such as the IJA’s Ki-109 and IJN’s P1Y2-S Kyokko, both of which, as well as other conversions, were unsuccessful due to it being unable to climb and reach the targets.
On 21 May 1943, a field-modified Nakajima J1N1 recon aircraft fitted with two 20 mm Type 99 cannons at an upwards angle managed to shoot down two B-17 bombers at Rabaul. This modified version of the J1N1 was a brainchild of Commander Kozono Yasuna of 251st Kokutai, who ordered the modification against high command’s orders who were skeptical about his idea. After this success, the high command’s preception of a delicated night figher interceptor has changed. The IJN would have later placed order for Nakajima to produce an interceptor variant of the J1N1 and saw great success against B-17 and B-24, whose utilizing a quirky ball turrets and cannot keep up with the plane.
However, when the B-29 made its debut in late 1943, the J1N1 is now somewhat inadaquate against the new threats. As the B-29 is able to fly at an altitude that the J1N1 barely reach, is fast enough that only one pass can be done to attack them, and is equipped with a remote-controlled turrets that can dispatch the J1N1 down. The IJN again found itself under the threat that they were unable to effectively counter.
Original design blueprints of the S1A1, note the slightly different nose shape.
Thus, in the end of 1943, the IJN issued the 18-Shi Hei order for a new delicated heavy night fighter and interceptor capable of reaching the altitude of the B-29. The specification required the plane to reach a maximum speed of 685 km/h at an altitude of 9,000 m, able to climb up to 6,000 m altitude in 8 minutes, 5 hours of flight duration per sortle, armament consisting of at least two 30 mm cannons, and mounted with radar equipment. Aichi aircraft company later accepted the order in November 1943, as they doesn’t have any urgent orders like the other company at that time.
.jpg.352aa23bc59f3a2c44d3b2154be00f10.jpg)
A blueprint of the S1A1, a hardpoint for 60 kg bombs and extra fuel tanks can be seen at the top.
Internal design of the S1A1, an airbrake and elevation mechanism for the frontal 20 mm cannons can be seen in the image.
The S1A1’s wing structure.
The S1A1’s control panel.
Blueprint of the nose section of the S1A1. There is the list of the components; 1) Antenna for TAMA 3 centrimetric radar 2) 30 mm 17-shi (Type 5) cannons 3) 20 mm Type 99 model 2 cannons in default frontal firing position 4) Elevation mechanism for Type 99 cannons to be fired in Schrage musik configurations 5) Aiming sight 6) Two 60 kg bomb hardpoints below the nose 7) 250 kg bomb hardpoint slightly behind the 60 kg bomb hardpoints.
The plane was given a unique designation of S1A1 by the IJN, as it was the first delicated night fighter project. The plane will be an all-metal, tail-dragging design with only its control surface is covered with canvas. The aircraft will be fitted with several advanced features not found in most of Japanes airplanes, such as hovering flaps and air brakes on the bottom of the fuselage and wings, oxygen-injected turbochaged engines, pressurized cockpit, a basic TAMA 3 search radar, and a remote-controlled turret with wide coverage.
The crew consists of two men; a pilot, and a gunner who sits behind the pilot in a small dome cockpit. The gunner utilize the remote-controlled rear turret which can be fully rotated and can aim upwards to hit enemy aircraft from below.
The main armaments consists of two 30 mm Type 5 cannons and two 20 mm Type 99 model 2 cannons (although some sources say that it was the earlier model 1 cannons), the nose-mounted 20 mm cannons have a special mechanism to elevate the gun at 30 degrees of angle to turned it into a “Schrage musik” guns to hit the bomber’s belly. The remote-controlled turret is fitted with two 20 mm Type 99 model 2 cannons and is able to fully elevate up to 90 degrees, again to deal the hit from below. The aircraft can be loaded with one 250 kg bomb under the fuselage hardpoint, or two 60 kg bombs hooked on a small hardpoint benearth the nose.
The S1A1’s engine configurations and landing gear mechanism.
Aichi finished the S1A1’s design in May 1944 and completed the mock-up in August 1944. When Aichi has started building the two prototype ordered by the IJN, however, they found that the estimated final aircraft is somewhat overweighted at 10 tons full load, and that the Navy-issued Nakajima Homare 22 engines is not powerful enough to power the S1A1 to its specified top speed. Aichi then scrambled to find a way to increase the engine power, such as trying to develop a new turbochargers, then changed to an oxygen-injected engine, and finally planned to change the engine into Nakajima Homare 24. Which caused the construction of the two prototypes to be delayed by several months.
The S1A1’s mockup under construction. Unfortunately, none of the image of the actual prototype survives today.
On 7 December 1944 (3 years after Pearl Harbour attack), the Tonankai earthquake, an 8.1 magnitude earthquake occured. The earthquake heavily damaged the Tokai region where the S1A1’s prototype is being constructed and the prototype is badly damaged. The two prototypes would meet its untimely end in 1945, with the first prototype (70% completed) were destroyed in a bombing run in 9 June 1945, and the second prototype (90 - 95% completed) which were relocated to Gifu were destroyed in another bombing run in 9 July 1945.
While the S1A1 is never completed, with the second prototype being very close to completion. In War Thunder, the Denko will fulfil a similar roles with the American counterpart; the P-61 Black Widow. The S1A1 is well equipped and well-protected enough to take down any aircraft at its rank, and will provide a unique experience for the Japanese pilot.
Specifications:
General characteristics:
Crew: two, pilot and gunner
Length: 49 ft 6.5 in (15.1 m)
Wingspan: 57 ft 5 in (17.5 m)
Height: 15 ft 1.5 in (4.61 m)
Wing area: 505.902 sq ft (47.0 m2)
Empty weight: 16,138 lb (7,320 kg)
Gross weight: 22,443 lb (10,180 kg)
Max takeoff weight: 25,375 lb (11,510 kg)
Powerplant: 2 × Nakajima NK9K-S (Homare 22) , 2,000 hp (1,500 kW) each at take-off
Propellers: 4-bladed
Performance:
Maximum speed: 360 mph (580 km/h, 318 kn) (estimated)
Cruise speed: 273 mph (440 km/h, 240 kn) (estimated)
Range: 1,054 mi (1,697 km, 916 nmi)
Ferry range: 1,553 mi (2,500 km, 1,373 nmi)
Service ceiling: 39,370 ft (12,000 m)
Wing loading: 44.4 lb/sq ft (126.6 kg/m2)
Climb to/in: 29,530 ft (9,000 m) in 14 min 45 sec
Armaments:
Offensive: 2 × 30 mm Type 5 cannons and 2 × 20 mm Type 99 model 2 cannons in adjustable mounts
Defensive: 2 × dorsal turret-mounted 20 mm Type 99 model 2 cannons in a flexible remote-controlled turret
Suspended: 1 × 250 kg bomb or 2 × 60 kg bombs
Radar: TAMA 3 search radar
Source:
Spoiler
Francillon, Ph.D., René J. Japanese Aircraft of the Pacific War. London: Putnam & Company Ltd.,
Japan Project Aircraft: Koei, ISBN 4-87719-490-8 C0031,
Imperial Japanaese Navy Warplanes: Green Arrow, ISBN 4-7663-3161-3 C0076
https://ja.wikipedia.org/wiki/電光 (in Japanese)
Уголок неба ¦ Aichi S1A Denko (in Russian)
https://www.secretprojects.co.uk/threads/aichi-s1a-denkô-night-fighter-am-25.6535/