Aichi S1A Denkô Night Fighter (AM-25)

First, this plane's code is AM25, or some times A90 within Aichi's company, and S1A1 in the IJN. This plane, also called 18 shi-hei sentoki (night fighter projected in Showa 18th, or 1943), was there because the navy wish her to catch and take down the B29s (by the way, the J5N Tenrai was also there at the same time). However at that time, no one knows that B29s would bomb Japan at the altitude of 4000m, thus this plane's fastest speed was at 9000m, and unfortunately she could not catch up with B29 since at 4000m the denko was much slower according to her plan report and performance calculations.

Some great new information here. Thanks a lot!

Question: The mystery designation “A90” revealed here very much resembles the so-called “SADP designations” (実用機試製計画番号) begun by the IJN Aviation Bureau in 1939. I have never seen an Aichi designation of this format and have assumed they were never assigned or had been destroyed at the end of the Pacific War. In your research at Aichi, had you come across any similar designations?

Again, thanks for this much-appreciated information. Regards, Harry
 
Last edited:
Result of the more based on many documents research, i think probability is high that Denko no.1 was bombed March 12, 1945 at Aichi Eitoku-aircraft plant and Denko no.2 was incinerationed Augast 15, 1945(The day the war ended in Japan).
Here is the video about the S1A1 Denko by me but, I'm sorry this is in Japanese.
But, take a watch 7:34~28:15, there is many information about construction and Performance of the S1A1 Denko. It is easy to understand even for non-Japanese speakers.
View: https://www.youtube.com/watch?v=-tPwHiQx46A
Amazing video, extremely impressive research!
 
Some great new information here. Thanks a lot!

Question: The mystery designation “A90” revealed here very much resembles the so-called “SADP designations” (実用機試製計画番号) begun by the IJN Aviation Bureau in 1939. I have never seen an Aichi designation of this format and have assumed they were never assigned or had been destroyed at the end of the Pacific War. In your research at Aichi, had you come across any similar designations?

Again, thanks for this much-appreciated information. Regards, Harry
it absolutly exists! In fact, the document name of denko's wind tunnel's report was simply "A90 wind tunnel report"!
 
it absolutly exists! In fact, the document name of denko's wind tunnel's report was simply "A90 wind tunnel report"!
Thanks for your rapid reply. I'm thrilled that you discovered and verified this designation! Were you able to come across any other A-?? designations at Aichi? Looking forward to your D3A video. Best Regards, Harry
 
Last edited:
Thanks for your rapid reply. I'm thrilled that you discovered and verified this designation! Were you able to come across any other A-?? designations at Aichi? Looking forward to your D3A video. Best Regards, Harry
When you read some business trip reports by Aichi kokuki KK, you will see that the Seiran is A80
 
When you read some business trip reports by Aichi kokuki KK, you will see that the Seiran is A80
Really wish I had a way of doing that! Thanks for this new information and for your hard work. Harry
 
Last edited:
Very interesting, thank you. It would be appreciated if you like to proceed with further informations.
I would proceed further, if you have any questions feel free to ask me.
The resouces I'd obtained are: "S1A1(Denko) Plan Book" (with official and original blueprints of fuseage of Denko that are used to construct the prototype), "S1A1 Performance Calculations"(calculate the performance of S1A such as top speed and climbing rate by utilizing wind tunnel information), "S1A1 Strength Calculations" (calculate the metal strength of S1A, but only the tail part remains), "S1A1 Wing And Tail Blueprints" (original construction blueprints of wing and tail", and "S1A1 Wind Tunnel Reports" (73 pages of S1A's wind tunnel reports".
 
The cover page of Denko's plan struction book (same kind of thing like thesis or essay today), this picture's copy right belongs to Mr. Watanabe so if you are going to use it somewhere else, remember to at a sticker ©渡边哲国.

5,電光 計画説明書_页面_001.jpg
 
Good news! I would like to share these ORIGINAL documents of Denko for FREE with us. Anyone who is interested in these documents could email me zhaoziyuan@g,ecc,u-tokyo.ac.jp
 
Aichi S1A Denko


Late in 1943 the Kaigun Koku Hombu issued the 18-shi-Hei specification, calling for a night fighter with 685 km/h max speed, 8 minutes climb to 6,000 m, take-off run of 400 m and 5 hours endurance.

By November the Aichi company started the design AM-25 and completed the mock-up in August 1944. The new airplane was a two seat heavy fighter denominated S1A, powered by two 2,000 hp. Nakajima NK9K-S Homare 22 radial engines, with oxygen and water/Methanol injection power boost and forced cooling fan, driving four-bladed, constant-speed airscrews. The armament was to be six Type 99-2, 20 mm cannons: two forward firing in the nose, two in the nose, mounted in 30-degree Schräge Musik configuration, and two in the rear fuselage turret.

In the heavy fighter/destroyer version the two angled cannons were replaced by a Type 5, 30 mm forward firing cannon. The night fighter version would be fitted with a Gyoku-3 AI radar, with the radiating antenna enclosed in a nose wooden radome and one Yagi receiver antenna mounted under the nose, a Taki-11 radio altimeter with two inverted ‘T’ dipoles mounted under the wings and a Taki-30 IFF device with rod antenna mounted in the back of the rear fuselage. The building of two prototypes was started in 1944, but they were both destroyed during Allied bombing raids.

Denko technical data

Wingspan: 17.5 m, length (with Yagi antenna): 15.10 m, height: 4.61 m, wing area: 47 sq. m, max weight: 10,180 kg, estimated max speed: 588 km/h, estimated service ceiling: 12,000 m.
 

Attachments

  • 155.jpg
    155.jpg
    1.3 MB · Views: 38
  • 384.jpg
    384.jpg
    748.2 KB · Views: 30
  • 385.jpg
    385.jpg
    941 KB · Views: 25
  • 386.jpg
    386.jpg
    762.8 KB · Views: 23
  • 387.jpg
    387.jpg
    774.7 KB · Views: 23
  • 388.jpg
    388.jpg
    791.8 KB · Views: 23
  • 389.jpg
    389.jpg
    745.8 KB · Views: 22
  • 390.jpg
    390.jpg
    717.5 KB · Views: 24
  • 393.jpg
    393.jpg
    912.7 KB · Views: 25
  • 407.jpg
    407.jpg
    698.9 KB · Views: 26
Back
Top Bottom