Kyushu J7W1 Shinden/J7W2 Shinden-kai

windswords said:
I did not know the production version was to have a 4 blade propeller. I really like the 6 bladed prop, very cool! :) the Ki-93 also had 6 blade props as did the prototype Ki-94-II. You have to wonder at what point is more propeller blades overkill though. The 5 blade prop was used in versions of the Spitfire so maybe 5 is the practical and useful limit. Maybe someone with an engineering background could shed some light on this...
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You want a prop with a prime number of blades. 1, 3, 5, 7, 11, ... This means that there is only one harmonic vibration frequency to worry about. 5 blades is about the optimum for ease of design in a controllable pitch prop.

I have seen an 11 blade prop on a modern turboprop (Beech King Air, I think), which does interesting things to the noise and prop efficiency due to the long and thin blades. But it's a tight fit to cram all the blade roots into the hub.
 
blackkite said:
Japanese technology was rather low level at the day. ;D
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I don't think that anyone had figured out just how bad it was to have the fuselage boundary layer in your intake at this time, neither the P-59 nor P-80 had boundary layer fences in their inlets.
 
blackkite said:
Hi! You can see engine exhaust nozzle shape for oil cooler ejector in this side view and model picture.

This picture's explanation is mistake. The equipment which called oil cooler is ejector for oil cooler. Engine oil can not be cooled by hot exhaust gas.
Or they define oil cooler as oil cooler +ejector?
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If designed correctly, an exhaust ejector tube can increase airflow through the overall structure, as well as providing some jet thrust. The Cessna 310 uses this concept to help cool the engines by increasing air velocity through the nacelles, for example.
 
does anyone has "試製震電 計画説明書" (Test Production Shinden - Project Instructions) of pdf version? If so I really need some help (original blueprints or manual books are also ok), I could also provide some project reports of other japanese planes in exchange
 

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I will ask the detail of this model to the museum. Give me time.
Perhaps this model is not a fully flying replica, or not a ground runner.
I don't see such a Youtube movie still now.
 
I would really like to see flying replica's of some of these lost 'birds, the sky would be a better place with them there.

Not going to happen but I can dream. Pretty sure modern materials and aeronautical science couild cure the few problems with handling etc.
 
Foo Fighter said:
I would really like to see flying replica's of some of these lost 'birds, the sky would be a better place with them there.

Not going to happen but I can dream. Pretty sure modern materials and aeronautical science couild cure the few problems with handling etc.
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If you ask some of the test pilots who flew Shinden or Curtiss Ascender prototypes that they had … er … satisfied their curiosity.

Both of those early canards needed extensive re-design to fly like a normal airplane. For example, they needed centres-of-gravity farther forward and rudders much farther aft.
 
Hi Rob,

riggerrob said:
If you ask some of the test pilots who flew Shinden or Curtiss Ascender prototypes that they had … er … satisfied their curiosity.

Both of those early canards needed extensive re-design to fly like a normal airplane. For example, they needed centres-of-gravity farther forward and rudders much farther aft.
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I once tried to create a Shinden model for X-Plane, staying as close to the historic information as I could, and the result was a plane that didn't fly very well. It would either show insufficient elevator autority, or end up stalling the main wing before the canard.

The reason might just be my own cluelessness regarding canard design, of course, combined with the greater sensitivity of canard design to subtle design details I might not have gotten right.

Regards,

Henning (HoHun)
 
riggerrob said:
If you ask some of the test pilots who flew Shinden or Curtiss Ascender prototypes that they had … er … satisfied their curiosity.

Both of those early canards needed extensive re-design to fly like a normal airplane. For example, they needed centres-of-gravity farther forward and rudders much farther aft.
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Imagine a world where canards of the *original* Wright Brothers design were considered "a normal airplane"...
 
I received following information from Chikuzenmachi Tachiarai Peace Memorial Museum.

The Oosawa company made this exhibition model.
This model has no engine.

会社情報｜映画撮影美術などのデザイン・製造の株式会社Oosawa

映画などの撮影美術・セット・大道具をデザイン製作する、株式会社Oosawa（大澤製作所）です。数々の実績をもつ私たちは、閃きと実現力で革新的なデザインを手掛けます。法人概要やアクセスマップはこちらからご確認ください。
www.oosawa.net www.oosawa.net

Today I watch ‘Godzilla -1.0 (Minus One).’
Shinden is very fascinating.
View: https://www.youtube.com/watch?v=PgkBPejm67I
 
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I suppose it depends if the 'replica' was constructed using proper build methods or is just a 'silhouette' or simple look alike which would have zero chance of engine fitment.
 
Hi!　NASM's Shinden with engine.
source : Zoukei-mura CONCEPT NOTE SWS No.1, J7W1 帝国海軍局地戦闘機　震電 (The IJN Interceptor Shinden)
 

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Sad to see it in that state tbh.
 
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I hope Shinden early restoration.
 

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Hi everyone,

Here some fresh images from a quite ambitious and well-researched 3D modelling project for the J7W:

Kyusyu J7W1 "Shinden" CGI Project

Great work so far shinpachi!
ww2aircraft.net ww2aircraft.net

The modeller "Shinpachi" is a Japanese engineer, I believe ... he might have said more on his background in the first 14 pages of the thread :) Very knowledgable and thorough guy in any case!

Regards,

Henning (HoHun)
 
Hi!
Source : SA SCALE AVIATION, VISUAL BIMONTHLY FOR SCALE AIRCRAFT MODELERS VOLUME 154, NOV 2023,
 

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I don't know quantitatively, but I think that the cooling air intake of the Shinden fighter does not have a fence to escape the boundary layer, and the speed of the incoming air is slower than the flight speed. Therefore, I think that a large cooling fan will be needed to obtain the speed necessary to cool the engine of the Shinden. In addition, there is no intermediate cooler after the first-stage compressor, and the air duct to the second-stage compressor needs to be cooled, so a large cooling fan is required.
 
Hi Noveos,

Noveos said:
View attachment 713511
I’m not sure if this is a silly question, but why is the mounting for the cooling fan so large in diameter?
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Not a silly question at all. I suppose the mounting is not only large, but also fairly substantial, as it has to transfer the torque loads between the engine and the propeller reduction gear mounted at just forward of the propeller that are induced by the driveshaft spinning at crankshaft speed.

Torsional vibration and fore-and-aft vibration of the engine-drive shaft-propeller system had been a serious problem on the Mitsubishi J2M Raiden ("Jack") fighter, which used an extension shaft with a tractor propeller, and I imagine the Japanese engineers learned from that. (See "The Zero Fighter" by Okumiya, Horikoshi and Caidin for a record of the J2M's problems.)

Another reason for a large "core" of the rear cowling might have been the internal aerodynamics, as you'd want to keep the air flow through the cowling as smooth as possible by avoiding abrupt cross section changes, but I imagine if that were the primary reason, the engineers might not have come up with the simple cylinder shape but something more streamlined.

Regards,

Henning (HoHun)
 
HoHun said:
Hi Noveos,



Not a silly question at all. I suppose the mounting is not only large, but also fairly substantial, as it has to transfer the torque loads between the engine and the propeller reduction gear mounted at just forward of the propeller that are induced by the driveshaft spinning at crankshaft speed.

Torsional vibration and fore-and-aft vibration of the engine-drive shaft-propeller system had been a serious problem on the Mitsubishi J2M Raiden ("Jack") fighter, which used an extension shaft with a tractor propeller, and I imagine the Japanese engineers learned from that. (See "The Zero Fighter" by Okumiya, Horikoshi and Caidin for a record of the J2M's problems.)

Another reason for a large "core" of the rear cowling might have been the internal aerodynamics, as you'd want to keep the air flow through the cowling as smooth as possible by avoiding abrupt cross section changes, but I imagine if that were the primary reason, the engineers might not have come up with the simple cylinder shape but something more streamlined.

Regards,

Henning (HoHun)
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Thank you and @blackkite for the responses! It makes total sense that torsional vibration would be a serious concern. So does this "drum" looking mount rotate or merely hold the extension shaft in place?
 
Hi Noveos,

Noveos said:
Thank you and @blackkite for the responses! It makes total sense that torsional vibration would be a serious concern. So does this "drum" looking mount rotate or merely hold the extension shaft in place?
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In the model picture you posted, it looks like it's a stationary structure to which the reduction gear housing is bolted. The front end probably is bolted directly to the engine housing.

(There are a lot of interesting diagrams in this thread, but I'm not sure any of them detail this particular aspect, so don't take my guess for the gospel ;-)

Regards,

Henning (HoHun)
 
Hi! Shinden propulsion system excluding propeller.
 

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