Aichi S1A Denkô Night Fighter (AM-25)

[snark]

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

 

[QAZ]

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!

 

[zzy2001]

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"!

 

[zzy2001]

Amazing video, extremely impressive research!

gladly, I am now cooperating with the video's uploader, and soon we will create a new video about D3A Val, please wait and watch!

 

[snark]

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

 

[zzy2001]

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

 

[snark]

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

 

[zzy2001]

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".

 

[zzy2001]

Aichi S1A1 original plans. The nose looks somehow different to the way it's always shown in non-original plans.

View attachment 613954

By the way, this picture comes from "S1A1 Performance Calculations"

 

[zzy2001]

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.

 

[zzy2001]

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

 

[Justo Miranda]

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.

 

[Justo Miranda]

Post-2

 

[zzy2001]

Hello, this is Zhao who spent a lot of time on Denko, welcome back.
In have translated all pages of "Denko Keikaku Setsumeisho"(Denko plan instruction) into Mandarin and also planning to do the samething by English.
Today I am going to share a few facts about Denko.
1. According to Mr. Watanabe, the man who restored the remaining Seiran in NASM, the Denko had some kind of close relationship with P1Y Ginga. When Dr.Ozaki (Denk's designer) was about to deal with the tricky requirements given by the Navy at 1944, Dr. Naito of Nakajima Heavy Industry (designer of C6N1 Saiun) came for some assistance. He gaves Dr.Ozaki some manuals of Ginga and at the same time some new technologies that where put into usage on Saiun. Thus Denko shared the similar outlines of Ginga and at the same time shared the same characteristcs with Saiun on her frame of fuselage (Saiun and Denko's fuselage have very few stringers but much thicker skins than other aircraft, this pattern would make them much faster since there were much lighter and at the same time brought them a huge reduction of production time).

Above is the ORIGINAL fuselage blueprint from Denko Keikaku Setsumesho
2. Denko was planned to carry some kind of unkown radar and computer similar to P61, the evidance is that on the final draft of Denko, the nose shape was different. However this unkown "radar" was all burnt and there where no photos of the prototype so no one knows what the hack was happening.

Denko's ORIGINAL final draft from "Denko Performance Calculations" completed in early 1945, about a year after "Denko Keikaku Setsumesho". Note that the nose shape was different.
3. Denko barely used any SDCH or SDH, instead she was using NDCH/NDCO and NDH/NDO as her main materials, the reason were to save production time and save Duranium.

 

[blackkite]

Hi!

 

[blackkite]

Hi!
I believe that engine exhaust gas (through turbocharger) outlet nozzle act as a ejector or a jet pump for inter cooler cooling air discharge.

 

[zzy2001]

Hi!
I believe that engine exhaust gas (through turbocharger) outlet nozzle act as a ejector or a jet pump for inter cooler cooling air discharge.

Hi, if you need the “Denko Plan instruction" too, I would also upload it here.
In fact, there are 35 graphs of Denko provided including the 2 dimension graph, the fuselage line graph, the fuselage assembly graph, the wing assembly graph, the main wing spar graph, etc. Most of them are not publicated so that I believe you will like it.

 

[zzy2001]