Kawanishi KX-03 giant 500-ton flying boat

[Pelzig]

New one to me. 500 tons? What a monster that would have been. The H11K Soku was the KX-8 internally to the company. If the designators went in order, then one can surmise that the KX-3 was a proposal which pre-dated the H11K. Still, I bet no sane military official would have given such a proposal much thought. A transport that big would have been highly vulnerable, regardless of the armament it may have carried. Just look at the Me 323's vulnerability when flying without benefit of air cover.

I'd love to know more about the design but I suspect it was a flash in the pan and was quickly shelved to work on more promising, and more realistic, designs.

Anyone knows Kawanishi super large 500 ton flying boat study called KX-03?

 

[Winston]

Any dimensions/specifications for this aircraft? I'd like to see how it compares to the Spruce Goose.

 

[Winston]

Enjoy your summer vacation blackkite, I will wait in anticipation!

 

[blackkite]

According to “もしもWEAPON”, the source of KX-03 are Kawanishi aircraft's technical report No541,544,566 ”500ton class flying boat study. The IJN ordered Kawanishi to study 500 ton class flying boat in the beginning of 1943.
Overall length;162m, Span;180m, Height;35.4m, Wing area;1,150square meter,
Gross weight;460ton, Range;18,520km, Payload;900 soldiers with normal equipments,
Engines; Ne201 turbo prop engine(7,000hp + static thrust 900kg/each engine)×12(total 132,000hp),
Ne330 jet engine×6(total equivalent 7,920hp), crews;24.
Ed! How about cover this study in your next work?
BTW according to another book"Kikka (miki shobo) ISBN4-89522-276-4 C0053 " Ne201's power was 1,870hp.(7,000hp is too large for Ne201,)
I think Ne201 was not applied this study. The engine of this study might be another secret studied engine.
I believe also KX-01 nad KX-02 were studied. I can't imagine what aircrafts were. (flying boat?)

 

[T-50]

Hi Blackkite san first Ill hope you had a nice vacantion,and second this is awsome new to me! a 500 ton heavy flying boat!
I ask my self those engines most be very powerfull to powe such big aircraft,even bigger than the B-36! Ill think at least engines of 7000hp!

 

[redstar72]

big aircraft,even bigger than the B-36!

If it was 162 m long and 180 m "wide", it was TWICE as big than ANY the biggest aircraft every built in this world - including the Spruce Goose and An-225 Mriya! And with 500 tons weight, it was almost as heavy as the Mriya, A380 and the Caspian Sea Monster!

 

[Pelzig]

Most interesting. If the information is correct, this implies that the study was continued into 1944-45. In 1943, the Ne 201 and Ne 330 weren't even on the table. Only the Ne 10 and Ne 12 were in development at this time. It was only in July 1944, with the advent of Eiichi Iwaya's arrival in Japan with the copy of a cross-section of the BMW 003A, was the Ne 20 and its derivatives discussed. It wasn't until June 1945 when the Ne 20 got anywhere near production (only 6 Ne 20 engines were available at this time). Mitsubishi never built any example of the Ne 330 by the close of the war.

This is pure speculation on my part, but if the KX-3 was something that was left on the table, the turbo-jet powered Kawanishi K-200 may have been derived from the design. The more commonly circulated contemporary illustration of the K-200 shows some similarity to the KX-3, notably in the hull and the placement of the jet engines on top of the wings. The K-200 wasn't even close to the KX-3 in terms of size but it was a much more reasonable design. Though, the K-200, even with six Ne 330 engines would have had abysmal range compared to the likes of the Kawanishi H8K.

But yes, Blackkite, the KX-3 may find its way into the second book. ;D

According to “もしもWEAPON”, the source of KX-03 are Kawanishi aircraft's technical report No541,544,566 ”500ton class flying boat study. The IJN ordered Kawanishi to study 500 ton class flying boat in the beginning of 1943.
Overall length;162m, Span;180m, Height;35.4m, Wing area;1,150square meter,
Gross weight;460ton, Range;18,520km, Payload;900 soldiers with normal equipments,
Engines; Ne201 turbo prop engine(7,000hp + static thrust 900kg/each engine)×12(total 132,000hp),
Ne330 jet engine×6(total equivalent 7,920hp), crews;24.
Ed! How about cover this study in your next work?
BTW according to another book"Kikka (miki shobo) ISBN4-89522-276-4 C0053 " Ne201's power was 1,870hp.(7,000hp is too large for Ne201,)
I think Ne201 was not applied this study. The engine of this study might be another secret studied engine.
I believe also KX-01 nad KX-02 were studied. I can't imagine what aircrafts were. (flying boat?)

 

[Winston]

This design is....well, mind boggling! Thanks blackkite! Also it would be great to see this design added into the second book Ed.

 

[blackkite]

Hi! I think this 7,000hp turbo prop engine is too large compared with the state of the art of Japan at the day.
About the engine,this Kawanishi study might have been only determined required engine size for 500 ton class flying boat.

 

[foiling]

Hey Blackkite, thanks for the data & general arrangement of the KX-03. Amazing that something so huge, even if only a very brief idea, could remain so unknown. Monstrous & impressive. Never a dull moment on this site.

 

[royabulgaf]

I did a bit of cypherin' based on the B-36 wingspan vs the KX-3. The wingspan is about 2.5 times the B-36s. Cubing this, I get a KX-3 volume of 16.625 times that of the B-36. Assuming similar construction methods and a B-36 gross weight of 130 tons, I get a weight of over 2000 tons. This is somewhat generous, as due to the square-cube law, construction would have to be sturdier. With a wing area of 443 sq meters, you get about .3 tons per square meter of wing loading. The KX-3 wing loading would be about six times as much. Am I missing something?

 

[windswords]

Just when I thought I heard everything. Blackkite, I can't believe this was a study ordered by the IJN. It seems more of a fantasy imagined by a bored aircraft designer. The Navy had to know that a plane like the KX-03 was impossible to build. however I will take your word on it because you have been an impeccable source of information in the past. Holy cow, is that a Fugaku in the upper left corner? The small single engine plane appears to be an A6M. You could have two story apartment in that wing!

 

[blackkite]

I did a bit of cypherin' based on the B-36 wingspan vs the KX-3. The wingspan is about 2.5 times the B-36s. Cubing this, I get a KX-3 volume of 16.625 times that of the B-36. Assuming similar construction methods and a B-36 gross weight of 130 tons, I get a weight of over 2000 tons. This is somewhat generous, as due to the square-cube law, construction would have to be sturdier. With a wing area of 443 sq meters, you get about .3 tons per square meter of wing loading. The KX-3 wing loading would be about six times as much. Am I missing something?

Wow surprising wing loading and gross weight!
Yes this study is very hard to believe for me,too.
The planes located top of the drawing are Fugaku, Zero and B-36.

 

[Pelzig]

I've passed along the information on the KX-3 to Shozo Abe to get his take on it as he is one of the most respected authorities on Japanese aviation, including Kawanishi. I will say that back in 2009, he was skeptical of the turbojet powered K-200 flying boat, having never heard of such a design in his studies to that date. Based on that, the K-200 almost didn't make my book but I left it in as the evidence to date has yet to 100% confirm or deny the K-200 project.

 

[blackkite]

I did a bit of cypherin' based on the B-36 wingspan vs the KX-3. The wingspan is about 2.5 times the B-36s. Cubing this, I get a KX-3 volume of 16.625 times that of the B-36. Assuming similar construction methods and a B-36 gross weight of 130 tons, I get a weight of over 2000 tons. This is somewhat generous, as due to the square-cube law, construction would have to be sturdier. With a wing area of 443 sq meters, you get about .3 tons per square meter of wing loading. The KX-3 wing loading would be about six times as much. Am I missing something?

Hi! royabulgaf.
I want to know your opinion for possible size of 500ton flying boat. 747 class?

 

[royabulgaf]

Understand, I am NOT an engineer of any type. Using the B-36 weight and wingspan as a baseline, I am getting something around 100 m wingspan.

 

[blackkite]

Thanks a lot. Good estimation! I think you have a keen sense of basic design.

 

[blackkite]

http://www.geocities.jp/zero1517jp/jnrs/jnrs0.htm#top1

This Japanese site shows following Kawanishi large flying boat project.
①K-60; Gross weight:80ton, Range:9,260km(5,000n.m), Engine:Mitsubishi Nu 5,000hp×4(Nu was a combined H24 liquid cooling 2,500hp ME2A engine with steam turbine drive cooling fan)
②Enlarged K-60;Gross weight:120 ton
③K-200(KX-03?);Gross weight:500ton?, Engine;15,000hp gas turbine engine.

This site also shows that KX-2(KX-02?)(K-90) was a 17-shi land fighter(J3K1)

 

[Pelzig]

Does the site list sources? I didn't see that it did but I may have missed it. Well, this may explain the K-120 flying boat, a designation I've seen floated around here and there. But now we have a conflict between two sources on the K-200. The one text the K-200 was illustrated in clearly was not as large as the other sources KX-3. So, are the two the same? Who is correct? Looks like more digging will be needed to find additional sources to confirm or refute these aircraft.

http://www.geocities.jp/zero1517jp/jnrs/jnrs0.htm#top1

This Japanese site shows following Kawanishi large flying boat project.
①K-60; Gross weight:80ton, Range:9,260km(5,000n.m), Engine:Mitsubishi Nu 5,000hp×4(Nu was a combined H24 liquid cooling 2,500hp ME2A engine with steam turbine drive cooling fan)
②Enlarged K-60;Gross weight:120 ton
③K-200(KX-03?);Gross weight:500ton?, Engine;15,000hp gas turbine engine.

This site also shows that KX-2(KX-02?)(K-90) was a 17-shi land fighter(J3K1)

 

[blackkite]

You are researching Kawanishi giant flying boat study. Do you get some inspiration for Kawanishi giant flying boat from those drawings?
Sorry off topic.

 

[Pelzig]

Biggest boat I'm seeking info for is the Kawanishi KX-03 500ton flying boat study.

You are researching Kawanishi giant flying boat study. Do you get some inspiration for Kawanishi giant flying boat from those drawings?
Sorry off topic.

 

[Stargazer]

Biggest boat I'm seeking info for is the Kawanishi KX-03 500ton flying boat study.

Here is the Kawanishi KX-03 as illustrated by a young Dutch artist on deviantART (he got mixed up over the company name in the image's title):
http://kara-alvama.deviantart.com/art/Japanese-Kawasaki-KX-03-Flying-boat-267543845

 

[Stargazer]

Topics merged. Thanks blackkite!

 

[blackkite]

Many thanks Star!

 

[theponja]

Is the study confirmed ? Because until now I understand we can't confirm if the study is real.

 

[blackkite]

The best way to confirm this studty is to get following Kawanishi's technical report. But I can't it get still now. I can't imagine how to get it.

According to “もしもWEAPON”, the source of KX-03 are Kawanishi aircraft's technical report No541,544,566 ”500ton class flying boat study. The IJN ordered Kawanishi to study 500 ton class flying boat in the beginning of 1943.

 

[royabulgaf]

Interesting- The pictures are quite small, but they sure seem to be the style of Bruce McCall's work.

 

[theponja]

Interesting- The pictures are quite small, but they sure seem to be the style of Bruce McCall's work.

I don't agree every Bruce McCall's work has a twist or something funny on it not on this case. and for me the style isn't the same.

 

[blackkite]

Hi! Choukaizan.(鳥海山)
T-50 san's work is excellent, great and beautiful. But I feel too under power any way. Need some additional turbojet engines?
日本海軍 : means the IJN.
鳥(tori or chou) : means the bird,　海(umi or kai) : means the sea,　山(yama or san or zan) : means the mountain.

 

[Nick Sumner]

I have to confess I'm a little confused by

"Nu was a combined H24 liquid cooling 2,500hp ME2A engine with steam turbine drive cooling fan"

The H24 - is this the Mitsubishi Ha 43 (Army designation - not issued a unified designation) that has been linked to the Ki 73 design that couldn't be built because the required machine tools to be sourced from Germany were unavailable?

I am completely at a loss to understand what a 'steam turbine drive cooling fan' could be.

 

[blackkite]

Hmmmm.........Give me time.

 

[windswords]

Not to nitpick, but does a "design study" qualify as a project? I would think a project would be a one whose purpose was to build an actual aircraft. The only thing I can compare it to is the concept cars at the auto shows that never make it to production (I'm talking about the "way out" concepts). Now don't get me wrong, I think this is absolutely cool, and I love talking about it. I'm just trying to classify things in my small brain space. ;D

 

[Stargazer]

The only thing I can compare it to is the concept cars at the auto shows that never make it to production

Not quite actually.

A concept study of a plane will NEVER take off. It is meant to evaluate the feasibility of a project.

Most of the time, concept cars are REAL one-of-a-kind hand-made cars that can be driven. The closest thing to a concept car would be a proof-of-concept aircraft, and these are usually company-funded efforts.

 

[windswords]

You are correct Stargazer, concept cars are actually built. Not the best comparison, just the one that occurred to me at the time. Of course a concept car might cost $200,000 while a concept aircraft could be many millions of dollars or Euros.

 

[blackkite]

I have to confess I'm a little confused by

"Nu was a combined H24 liquid cooling 2,500hp ME2A engine with steam turbine drive cooling fan"

The H24 - is this the Mitsubishi Ha 43 (Army designation - not issued a unified designation) that has been linked to the Ki 73 design that couldn't be built because the required machine tools to be sourced from Germany were unavailable?

I am completely at a loss to understand what a 'steam turbine drive cooling fan' could be.

Hi! This is a typical nuclear power station cooling systm.
In our case generator is forced cooling fan. Nuclear reactor is the engine. Condenser is radiator.

 

[blackkite]

Hi!
My guess for steam turbine drive forced cooling fan concept.
I think that the objective of steam turbine drive forced cooling fan is to realize small size radiator air inlet and small size radiator for smaller drag same as Raiden's forced cooling fan.
Or to realize pusher type propeller.

In 1941, the IJN ordered Kawanishi to develop K60 flying boat which had 9269km(5000n.m) range to go and return Hawaii from Japan and 80ton gross weight. The engine were 4×Mitsubishi Nu engine which combined two ME2A H24 liquid cooling engine. Nu engine's power was 5000hp each. Nu engine had steam turbine drive forced cooling fan. In 1942, K60 was cancelled because there were no reason for existence of flying boat. Also Nu engine was cancelled.

 

[Jemiba]

Just a question about the term "forced cooling": Doesn't it mean, that cooling is always provided,
when the engines is running, in the case of air cooling by a fan coupled directly to the shaft?
That would mean, that a separate electrical motor or turbine driving the cooling fan (or maybe
the pump for the cooling liquid) wouldn't qualify as "forced cooling", because it could be simply shut
off, when the engine still is running.
Sorry for spoiling your sketch, it's just as an illustration and was quicker, than to draw it completely new ..

 

[blackkite]

Hi Jens!
I believe that "forced" means "forced circulation(blowing) by pump or fan" or "forced convection by pump or fan".
For example natural convection boiler(small boiler) has no circulating pump, forced convection boiler(large boiler) has a circulating pump.
Attached drawing's left side boiler is natural convection boiler, right side boiler is forced convection boiler.
循環ポンプ = circulating pump

Both air cooling engine and liquid cooling engine, the final heat sink is the air. Liquid cooling engine has a radiator. Radiator is a air/liquid heat exchanger which has large heat transfer area nevertheless it's compact size. Air cooling engine's heat transfer area is fin area which connected to engine cylinder. Fin area is limited by cylinder layout and fablication technology. On the other hand, it's easy to design large heat transfer area radiator. So liquid cooling engine has good performance at low air density high altitude. Air cooling engine's high altitude performance is rather low compared with liquid cooling engine because it's heat transfer area is small and discharge heat is small. When air cooling engine keeps excessive high power at high altitude, the engine face over heating.
I think it's one of the reason why Dora was required.

Zero and spitfire's engines were of course forced cooled by propeller stream. But in case of Raiden, air inlet size for engine cooling was too small(because of low drag design) for forced cooling by propeller stream, it's necassary to had forced cooling fan.

 

[Jemiba]

There may be different definitions, but the switchgear cabinets for telecommunications, I was working on years ago,
had "forced cooling" as a design point and explicetly stated in the delivery contracts: Already when they were connected
to the electricity grid only, two large electrical fans started to blow air. So, the installation simply couldn't be run without
cooling. The same applies to the power supply of your computer:The loudest and most annoying sound starts, when you
push the button, not matter, if the HD or the processor is already working. So, for a piston engine a "forced cooling" would
have to be coupled to shaft of the engine, which shall be cooled, because otherwise it could be shut off accidentally,
intentionally or maybe due to a failure, provoking damage to the engine. Convection cooling actually IS a form of forced
cooling, but with quite low efficiency only (as can be seen, for example in the datasheets of power supply units, there are
often both variants, but those with a fan in most cases have at least triple the power output). The Raiden, as well as the
Fw 190 with BMW 803 had a fan directly on the prop shaft, so there was no way to shut it off, a classical example of "forced
cooling" in the way, I'm thinking of it.
But I have found no "official definition", so, as said before, there may be different interpretations of that term.

 

[blackkite]

Hi Jens!
I want to know your opinion for Mitsubishi Nu engine coolig system diagram which had steam turbine drive forced cooling fan.
Is this?