Yokosuka (Kugisho) « Keiun » (R2Y1) and « Keiun-kai » (R2Y2)

elmayerle

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Is the Yokosuka Tenga any relation to the R2Y2? BTW, this engineer is dis-satisfied with most drawings he sees of the R2Y2 with two jet engines buried in the center fuselage above the wing and a nose intake replacing the propeller. That long an intake would lead to thoroughly nasty inlet losses and flow distortions. I find the side view from one old French magazine, with podded engines under the wings to be far more plausible. Now, and advanced R2Y3 with fuselage engines and wingroot intakes I could see, but not what's commonly shown.
 

lark

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Hesham ,can you show us the sources of your information?

As far as I know , the so called 'Tenga' was not a real project but
only an idea in someone's mind about a jetpowered Ginga variant
but this aircraft was far to heavy for the Japanese jet engines at that time...
 

hesham

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Sorry TsrJoe,

I have no drawings or data to them.

the Yokosuka Tenga became P2Y and there was also anther rocket aircarft
Mizuno Shinryo II .
 

Flitzer

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Hi all...
Has anyone any information about the jet powered Kugisho R2Y2?

Was it army or navy?

Any idea of dimensions?

I culled from site the 3 version side view plate and would like to find a top view etc.

Many thanks
Peter
;D
 

hesham

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Hi Flitzer,

the Kugisho R2Y2 was developed from R1Y1 and its name Keiun-Kai,
and it can carry one 800 kg bomb,it was designed for Navy of course,
also see;
http://www.j-aircraft.com/artwork/yokosuka_r2y2.htm
 

elmayerle

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hesham said:
Hi Flitzer,

the Kugisho R2Y2 was developed from R1Y1 and its name Keiun-Kai,
and it can carry one 800 kg bomb,it was designed for Navy of course,
also see;
http://www.j-aircraft.com/artwork/yokosuka_r2y2.htm
*chuckle* For what it's worth, I put together the drawings of the R2Y2 that Richard Lewis Mendes used for that artwork. I'll have to check back on the source article for the drawing, but I always found this engine installation far more plausible than the fuselage-mounted engines with nose inlet that some sources show; the duct losses in that inlet would be unreal, let alone the flow distortions that could occur.
 

elmayerle

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Flitzer said:
Hi all...
Has anyone any information about the jet powered Kugisho R2Y2?

Was it army or navy?

Any idea of dimensions?

I culled from site the 3 version side view plate and would like to find a top view etc.

Many thanks
Peter
;D
From the designation, it was clearly Navy. If I can find 'em, I'll be glad to supply you with the same data I supplied to Richard Mendes. Drop me a PM or email if you're interested.

Best,
Evan
 

Jemiba

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Sorry, I have no top view of the R2Y2, just of the R2Y1, for the R2Y2
it's just a side view. But I think, lenght and span were the same:
span 45ft, 11in, lenght 42ft, 9 1/4in, height 13ft, 9in, wing area
365.973 sq.ft
powerplant were two Ne-330 jet engines of 2.904 pounds thrust,
estimated speed 447 mph, range 2.180 miles at 287 mph, service
ceiling 32.800 ft.
(from RAF Review 04/59)
 

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elmayerle

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That's basically the side view I have, though mine's taken from a French article. I'm still digging to find the drawings I made for Richard Mendes, I worked up a 3-view the basic aircraft and then a couple variations in line with other things the IJNAF was doing at the time. As soon as I can find them, I'll make scans available.
 

Flitzer

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Many many thanks elmayerle.
Great stuff.

I've started a profile for one of the versions...
work in progress. I can't vouch for the accuracy of the camo scheme or markings.

Many thanks again
Peter
 

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elmayerle

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Flitzer said:
Many many thanks elmayerle.
Great stuff.

I've started a profile for one of the versions...
work in progress. I can't vouch for the accuracy of the camo scheme or markings.

Many thanks again
Peter
The profile you're using is one I have real problems with. The nose inlet, combined with the engine location, is going to make for very poor engine efficiency between duct losses and inlet distortion. That's why I think the version shown in Jemiba's profile, with underwing engines, is far more probably. Now, if you went with wing-root intakes, this engine location would work quite well, but with a nose intake, it's just plain asking for trouble, IMHO.
 

Flitzer

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Hi elmayerle...

I agree with your comments.
When starting this one, I questioned the nose intake feeding two engines so far back, but this version is labelled as the most likely version that would have been selected for development on the Hikoki 1946 site.

But I hope to do profiles for all versions. The one illustrated just happens to be the first one out of photoshop... ;).

Again the scale views of the wing root intakes and the Me 262-esque underslung engines versions are exactly what I need. Many thanks.

Cheers
Peter
 

elmayerle

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Well, I've often thought that the wing-root intakes of the high-speed versions of the Messerschmitt P.1099/P.1100 designs would be quite applicable here (if one wants to really speculate, a high-speed, swept-wing R2Y3?). I'm still digging for my three views but I can send you the scanned French article with the side view I started from. The party who scanned it for me did so in a pcx format; do you have a graphics program that can handle that? If not, I'll convert to jpgs and send from home tonight.
 

Flitzer

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Again many thanks elmayerle.

You are a real help.

I use an old Mac at work...lunch times of course...so I'm not sure the pcx format will work.
So if you don't mind jpgs would be perfect.

Again many thanks
Peter
 

elmayerle

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Flitzer said:
Again many thanks elmayerle.

You are a real help.

I use an old Mac at work...lunch times of course...so I'm not sure the pcx format will work.
So if you don't mind jpgs would be perfect.

Again many thanks
Peter
jpg's have been sent. Scans of the drawings I did will be sent this weekend. I'll also send an explanation of the variants I schemed up.

Best,
Evan
 

sagallacci

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Regarding the jet version of the R2Y1, I recall that years ago I saw, in a Japanese publication, a photo and very small/limited detail illustration that proported to be a machine actually built. The photo was of a wreaked fuselage center section with wing root ducts and the illustration was of the engine installation. Of particular note was that the engines were staggered in the fuselage. I'll try to find the material, though I have not seen anything related to that anywhere else.
 

borovik

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sagallacci said:
Regarding the jet version of the R2Y1...
sorry, source unknown.
Also on page 3 (Reply # 40), that the same threads have a wonderful color projection P.Allen aka Flitzer.
http://www.secretprojects.co.uk/forum/index.php/topic,661.30.html
Re: Japanese stuff
« Reply #91 on: August 27, 2008, 12:37:18 am »
Could anybody help me identify these projects?
http://www.secretprojects.co.uk/forum/index.php/topic,661.90.html
Better late than never
Number 4 [Escanear0004.jpg] is the Kawanishi H11K. (swallow right)
from: "The XPlanes Of Imperial Japanese Army & Navy 1924-45"
 

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elmayerle

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borovik said:
sagallacci said:
Regarding the jet version of the R2Y1...
sorry, source unknown.
Also on page 3 (Reply # 40), that the same threads have a wonderful color projection P.Allen aka Flitzer.
http://www.secretprojects.co.uk/forum/index.php/topic,661.30.html
Re: Japanese stuff
« Reply #91 on: August 27, 2008, 12:37:18 am »
Could anybody help me identify these projects?
http://www.secretprojects.co.uk/forum/index.php/topic,661.90.html
Better late than never
Number 4 [Escanear0004.jpg] is the Kawanishi H11K. (swallow right)
from: "The XPlanes Of Imperial Japanese Army & Navy 1924-45"
The R2Y2 with underwing engines or with wing-root intakes are designs that make sense. The version with a nose intake just doesn't make sense from the duct loses you'd get with the long duct as well as the valuable fuselage "real estate" such a duct takes up. To my way of thinking, the underwing version would be the easiest and done first, followed by the one with wing-root engines inside the fuselage(note, this also allows you to sweep the wing for a higher-speed version).
 

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This is my take as well. Mounting the engines on the wings was simply the most expedient way to equip the R2Y1 with jets. Did the Japanese consider the nose intake idea? I don't doubt they did, especially if one considers the Army design for a single seat jet as put forward by Captain Hayashi which had the engine mounted in the tail with a nose intake, similar to the F-84. But the main issue was the Japanese had no time to fully investigate the effects of long intakes and the Germans likely did not share what research they had on the topic with the Japanese. And even the Germans didn't get the P.1101 off the ground to even validate their research, let alone the Ta 183 making it. If you look at all of the high performance jet aircraft the Germans fielded or flew, all used nacelle mounted engines (Me 262, Ar 234, Ju 287, He 162, He 280). I don't include the He 178 as this was only a technology demonstrator, not a combat aircraft. And if you look at the Japanese jet designs, again, just about all of them used external engines (Tenga, K-200, Kitsuka, R2Y2, the turbojet Gekko project, and the competing Army design for a single jet fighter by Captain Yasuda) with the exceptions of Hayashi's design and the R2Y2 variants and, I imagine, you could lump in the turbojet Oka models.

As for a picture that alludes to showing the jet version of the R2Y1, I'd have to view it with skepticism. I've sometimes seen the photo of the second, incomplete R2Y1 described as having been modified to mount jets but that simply wasn't the case. Even the completed R2Y1 had wing intakes and as the design had rather severe cooling problems, if the second fuselage did have altered wing intakes, it was to cool the Aichi engine, not for jets (not near by library to check!).

Cheers,

Ed


elmayerle said:
The R2Y2 with underwing engines or with wing-root intakes are designs that make sense. The version with a nose intake just doesn't make sense from the duct loses you'd get with the long duct as well as the valuable fuselage "real estate" such a duct takes up. To my way of thinking, the underwing version would be the easiest and done first, followed by the one with wing-root engines inside the fuselage(note, this also allows you to sweep the wing for a higher-speed version).
 

T-50

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Hi blackkite san you did it again! I didnt know there were more pics about the beatiful cloud!I thought the war has destroyed most of the pics.
Im glad there are more surviving pics of this again very extraordinaire plane,I know there were plans to reequip this plane with jet engines
thanks again to share this rare photo material with us!
cheers
T-50
 

blackkite

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Stargazer2006 said:
blackkite said:
Kugisho engineers called her Okeichan(お景ちゃん).
Which means... ?
Keiun is 景雲.
景 means scenery. 雲 is cloud.
In Japan, we use letter 景 for woman's name. For example 景子(keiko).
子 means child. Many Japanese women have this letter 子 for her name. For example 雅子(Masako, the name of Japanese princess name as you know).
Okeichan is Keiko's pet name. Generally 景子 are very beautiful girls. ;D For example Keiko Takeshita.

http://talent.yahoo.co.jp/pf/detail/pp2714

http://search.babylon.com/?s=img&babsrc=HP_ss&q=%E9%9B%85%E5%AD%90%E5%A6%83
 

Stargazer2006

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Thanks for the explanations! So what is the word "onna", then? I thought that was the word for woman...
 

blackkite

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Onna(woman) is 女. Man is otoko(男).
 

hesham

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Excellent my dear Justo.
 

windswords

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Why in the jet proposal (R2Y2) are the Keiun's engines offset? Wouldn't that create a weight imbalance as well as a thrust imbalance? ???
 

theponja

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blackkite, Just thanks a lot for the pictures. They're great. :D :D :D
 

fockewulf261

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Hi, Flitzer. I noticed that the R2Y2 is described as a twinengined fighter. But in the specs you gave it one engine.
 

blackkite

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windswords said:
Why in the jet proposal (R2Y2) are the Keiun's engines offset? Wouldn't that create a weight imbalance as well as a thrust imbalance? ???

Hi! I think that the purpose of offset engine is to reduce fuselage cross section area. Small fuselage cross section area resulted low drag.
 

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blackkite

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(Part 1)
In 1941, Kugisho planned land base strategic reconnaissance aircraft as 17-shi land base reconnaissance aircraft(Y30, R1Y1). (Y10: Suisei(彗星), Y20 : Ginga(銀河)).
Kugisho Y30 (暁雲,Gyoun: the morning cloud) specification was as follows.
Engine : Mitsubishi ME2A H shape 24 cylinders liquid cooling engine×2(side by side) with steam turbine drive forced cooling fan, total 5000hp.
Propeller : single propeller, Maximum speed : 360kt(667km/h/6000m), Cruising speed : 250kt(463km/h/4000m), Range : 4000n.m.(7400km at cruising speed) .
Finally Y30 with ME2A engine was abandoned because it's difficult to realize such a radical plan, forward view was bad and did not fulfill required performance.

Then twin propeller aircraft which use two Mitsubishi MK10A engine(2400hp) was planned as Y30. Planned performance was as follows.
Maximum speed : 350kt(648km/h/6000m), 370kt(685km/h/8000m),(while required maximum speed top was 360kt(667km/h/6000m)
The IJN rejected this plan, because Y30 with MK10A did not fulfill the IJN's maximum speed requirement. Y30 with MK10A had a Ginga like shape, and more smart. Also MA10A engine had many problems.
 

blackkite

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(Part 2)
Finally commander Masao Yamana of Kugisho offered following plan based on imported He119 bomber.
Engine : Aichi Atsuta AE1T(DB601 series), take off power 1,700hp×2(side by side),
Maximum speed : 390kt(722km/h/10000m), Range : 1800n.m.(3300km/250kt(4000m))
Pressurized cabin, With turbo charger, 3.9m Extended propeller shaft, Single propeller, Wing loading : 238kg/square meter,
The IJN ordered Kugisho to develop this plan as Y40 Keiun (R2Y1). But it's difficult for Kugisho to continue development of Y40, because Kugisho's engineers were very busy to solve existing new planes problems.
At the time, Japan got jet engine technology from Germany, Kugisho offered jet powered Keiun-kai plan to the IJN. Keiun-kai's specification were as follows.
Engine : Mitsubishi Ne330 turbo jet engine(thrust 1320kg)×2, Maximum speed at S.L. 430kt(796km/h), Range 650n.m.(1300km)
The IJN ordered Kugisho to develop jet powered Keiun-kai as R2Y2 immediately.
Kugisho also offered to continue development of R2Y1 Keiun to get technical data for R2Y2, and the IJN agreed this offer.
 

blackkite

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(Part3)
In May 1945, Kugisho completed Keiun without pressurized cabin and turbocharger by rush work, transferred Keiun from Yokosuka(横須賀) factory to Kisarazu(木更津) base for flight test.
In the ground test, W shape engine's inner cylinders and oil temperature increased excessively, temporally air inlets were added one by one. In 29th of May, when the first flight, rapid oil temperature increase and engine bay fire happened, made emergency landing after only one turn above the runway. Very big air scoop was added to Keiun after this accident. In 31th of May, when engine ground test, engine stick happened by mistake, let Keiun alone until the end of the war. After the war, the U.S. Wanted Keiun, they had a one picture of Keiun, but Keiun was already exploded by the IJN's indiscriminate explosion team.
http://gunsight.jp/c/keiun-3D.htm
 

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