Japanese Rammer Project

[Pelzig]

Also in the Maru Special book on the Reppu (which, if you love the Reppu, this book is for you. Hobby Link Japan has it on backorder right now) was this little bit in the back. It is a sketch of a rocket powered rammer. Another piece of art elsewhere in the book shows two of them in action, one having cleaved off the tail plane of a B-29. It would appear it was recoverable as the wing tips were depicted as having landing skids and it looked to be heavily reinforced to enable it to survive the impact and that the cockpit and canopy were armored. I don't recognize much out of the text save it is a 1944 or 1945 concept.

We know the flood gates of German technology were finally opened in 1945 and perhaps some of the German rammer plans or concepts filtered over? It has a wingform much like the Kayaba gliders and Katsuodori ramjet fighter and, dare I say, a Lippisch-like tail with the cockpit blended into it.

Someone taking a crack at the Japanese may shed some light on it. Be interesting if it was a genuine project and not something made up.

One of the other neat drawings was a profile of a turbojet powered Nakajima J1N Gekko.

Cheers!

 

[moin1900]

Hi everybody

Thanks a lot for the sketch ! Pelzig
Very interesting design ! There are still some unknown projects !

"Another piece of art elsewhere in the book shows two of them in action, one having cleaved off the tail plane of a B-29."
Wow ! Maybe you can show us the picture ?

Here the Kayaba Katsuodori
http://www.j-aircraft.org/xplanes/

Thanks a lot in advance

 

[lark]

If you'll take a look on the Peter's - Flitzerart- site
you will see the Katsudori in all it's glory...

(Japanese secret projects chapter)

 

[Pelzig]

Here is the color picture. It spanned two pages, hence the line in the middle.

Wow ! Maybe you can show us the picture ?

Thanks a lot in advance
moin1900

 

[moin1900]

Thanks a lot ! Thanks for the fast reply ! Pelzig
Many greetings

 

[Antonio]

That's great finding, thanks Pelzig

 

[Pelzig]

Quite welcome! I'm hoping someone can summarize the article so we can all learn more about the design. ;D

That's great finding, thanks Pelzig

 

[Justo Miranda]

Here some speculative drawings of Ginga variants,from UNKNOWN! N.3

 

[Pelzig]

Do you have any verification on the sources for the Oka 53 being unmanned? On another forum, the topic came up and the unmanned Oka 53 was considered a post-war fantasy.

Here some speculative drawings of Ginga variants,from UNKNOWN! N.3

 

[Justo Miranda]

Ohka 53 sources (Post-1)

 

[Justo Miranda]

Ohka 53 sources (Post-2)

 

[Pelzig]

I guess my inquiry wasn't clear. ;D

I know the Oka 53 was planned. The question concerns where is the evidence to suggest it was not a manned weapon but was, instead, a unmanned glider bomb that was towed aloft. A manned Oka 53 could certainly be towed up and in most sources, this is implied but never stated one way or the other.

???

Ohka 53 sources (Post-2)

 

[Justo Miranda]

Ohka 53 sources (Post-3)
From "Japanese aircraft of the Pacific War" by René J. Francillon
Putnam 1970

 

[Justo Miranda]

Ohka 53 sources (Post-4)
From "Japanese Aircraft Industry in WW2"
USAF 1946 Report
ISO Publications

 

[Justo Miranda]

Ohka 53 sources (Post-5)
From http://pelzigplatz.f2s.com/hikoki_files/ohka.html

 

[Justo Miranda]

Ohka 53 sources (Post-6)
From "Le Fanatique de l´Aviation" N.66

 

[Justo Miranda]

Ohka 53 sources (Post-7)
Correspondence with Masahiro Ohno,April 1997

 

[Justo Miranda]

Ohka 53 sources (Post-8)
From "Lotnicy Smierci"
Via Thope

 

[Pelzig]

This is the version of the Oka 53 I'm talking about. ;D

The only evidence we have is that the Oka 53 was towed and powered with a Ne 20 engine. But I have seen no evidence to support that there was no pilot in the Oka 53.

The IJN was already working on guided missiles, mainly for anti-ship duties, in the I-Go series. The whole point of the Oka was to have a pilot in it as the means to guide the weapon to target. Unless the unmanned Oka 53 had some sort of guidance system in it, it made little sense to tow it up, release it, and hope it hit something.

;D

Ohka 53 sources (Post-8)
From "Lotnicy Smierci"
Via Thope

 

[lark]

Justo's drawing shows the Ohka 53 with
an antenna on it's back.Maybe we may assume that it
had a kind of a radio guiding device on board..

 

[Pelzig]

Very true. But I've looked through over a half dozen sources and none of them mention any sort of remote guided missile version of the Oka. The IJN was already expending good effort in the Ki-147, Ki-148, and I-Go-1C. It makes no sense on the surface and here is why. The Ki-147 and Ki-148, despite relatively successful results, both had a flaw. The flaw was they had to operate within 7 miles of the target since the launch aircraft had to follow the missile to allow the operator to bring the missile onto the target. This range was even less than the operational Oka Model 11 and we all know the poor results they had against Allied fighter protection. The I-Go-1C offered the only real option since it was, in essence, fire-and-forget. Even the Ke-Go might have been more useful, as, again, the bomb could be left alone once dropped.

So, you have a Oka 53 that is remote guided. Sure, the use of the Ne 20 grants a significant range boost over the Model 11 and Model 22. But you still have to be within close range for the operator to get the missile to the target, thereby nullifying any range advantage offered by the turbojet. If the Oka 53 was piloted, you wouldn't have that problem. The Oka 53 could be towed up and released far from the target, allowing the launch plane to survive.

So, in my thinking, the unmanned, guided Oka 53 just isn't coming up as logical and certainly, such a radical variation of the Oka design would certainly have shown up in postwar sources somewhere.

But, as always, I could be wrong. ;D

Justo's drawing shows the Ohka 53 with
an antenna on it's back.Maybe we may assume that it
had a kind of a radio guiding device on board..

 

[Justo Miranda]

German radiocontrol technology?

 

[Pelzig]

Possible. But a 1945 U.S. Navy report determined that the guidance systems used in the Ki-147 and Ki-148 were simple and relatively crude and no mention was made of the systesm being derivatives of German technology.

If the Japanese did receive specific data on German missile guidance systems, they either didn't apply it or the efforts made with the Ki-147 and Ki-148 were the first attempts at it. Either way, the war ended before anything better could be assembled.

But a look at what is thought the Japanese received might send a clue. The Hs 293 and Hs 294, again, had a range of only 9 miles, still less than the Oka Model 11. Again, you have the problem of being too close to the target and the usual air cover. Fritx-X, under 3 miles, and definitely not a contender. The only real possibility was the BV 246 Hagelkorn that the Allies figured the Japanese had access to data by early 1944. It used a IR homing system, was "fire and forget", and was designed as a anti-ship weapon. This was the exact mission profile of the Ke-Go. The Japanese were also expending considerable effort in IR homing.

So, you can see that the argument can be made that, perhaps, the Oka 53 was to be built using a IR homing method that would allow it to be fired from a good distance but in the direction of the target, and it would be fire-and-forget, guiding itself to the target.

But, again, we fall back to the fact that, at least to me, there is no wartime evidence supporting the unmanned Oka 53, only the vague references to the Oka 53 being towed into the air and using a Ne 20.

German radiocontrol technology?

 

[Pelzig]

Interestingly, a U.S. Navy report from 1946 on Japanese heat-seeking equipment mentions a "air to ship high angle guided missile." The report also specifically mentions the heat seeking bomb (Ke-Go) so it isn't confusion.

The Ki-147 and Ki-148 were all radio guided. The I-Go-1-C used shockwaves as a means to home in on targets, and it isn't the Ke-Go.

So, exactly what missile are they talking about? Perhaps the Funryu 1?

 

[Justo Miranda]

From "USAF 1946 report"

 

[blackkite]

Hi! According to Japanese text of Pelzig's first post,

1.This supersonic rocket fighter is discovered from the stock document of Japanese National Institute for Defence Studies.
2.This plane was joint project between Japanese Army and Navy.
3.It was half size of Shusui（秋水） rocket fighter.
4.This plane had the same solid rocket engines which installed to ohka(桜花）.
5.Time to climb to 10,000m was only 32 seconds while Shusui costed 3 minutes 30 seconds.
6.This fighter had no armament except it's robust wing to cut B-29 by mid air collision.
7.Manufacture of this fighter is not reported in this text.

 

[ryusuke]

Hi Justo,

Your information of Ke-Go (Maru Ke) from USAF 1946 report tells that Mark IX was to have 200 to 300 kg explosive. But, the US Navy report tells that Model 109 (probably means Mark IX) was to have 20 to 30 kg explosive. Which do you think is correct?

Cheers,
Ryusuke

 

[Justo Miranda]

Sorry, no additional info available :

 

[Pelzig]

Speaking for myself, I would trust the U.S. Navy report much more than the USAAF report (why the book reads USAF when the USAF didn't exist in 1946, I dunno) as the U.S. Navy's report is far more thorough and the USAAF report simply seems to have swiped work from the Navy in it.

30kg does seem rather light for such a large weapon and the weapon itself is rather heavy. Could the USAAF be right? Was it a typo in the Navy report that the USAAF fixed in theirs? Or was it a typo in the USAAF report?

Though, the bomb, due to its trajectory, would have struck the decks and superstructure of the ship which wouldn't necessarily need a heavy warhead.

One of the joys of authorship when it is difficult to collaborate data and you have to pick on or the other...or hedge your bets and include both.

Hi Justo,

Your information of Ke-Go (Maru Ke) from USAF 1946 report tells that Mark IX was to have 200 to 300 kg explosive. But, the US Navy report tells that Model 109 (probably means Mark IX) was to have 20 to 30 kg explosive. Which do you think is correct?

Cheers,
Ryusuke

 

[ryusuke]

Thank you, Justo and Pelzig

As you say, I also trust the U.S. Navy report than the USAAF report.
The navy report includes almost all the information and technical drawings. Very detailed and seems very accurate, except one mistake. Yes, the explosive charge was not 20 to 30 kg. The USAAF report is correct about it.

I found the backup information in a Japanese book. It is 'Rikugun Koku Kosho Shi (The history of the army aviation factory).' In the book, it is written as 'the explosive charge of Maru Ke was 200 to 300 kg.'
It was a kind of Sakura-dan/Ta-dan (shaped charge).
I am happy to find it. Even some Japanese historian incorrectly believe the explosive charge of Maru Ke was 600 kg.

HTH,
Ryusuke

 

[Pelzig]

Good news, indeed! ;D

Always a good thing when one can back up another source. Most interesting. Come to think of it, one of the illustrations in the U.S. Navy report certainly shows the shaped charge to good effect.

Ah, very true. I think I know one source you speak of with the 600kg warhead listed. ;D

Thank you, Justo and Pelzig

As you say, I also trust the U.S. Navy report than the USAAF report.
The navy report includes almost all the information and technical drawings. Very detailed and seems very accurate, except one mistake. Yes, the explosive charge was not 20 to 30 kg. The USAAF report is correct about it.

I found the backup information in a Japanese book. It is 'Rikugun Koku Kosho Shi (The history of the army aviation factory).' In the book, it is written as 'the explosive charge of Maru Ke was 200 to 300 kg.'
It was a kind of Sakura-dan/Ta-dan (shaped charge).
I am happy to find it. Even some Japanese historian incorrectly believe the explosive charge of Maru Ke was 600 kg.

HTH,
Ryusuke

 

[ryusuke]

It was because one member of Maru Ke project wrote it in his memoirs after the war. He wrote the explosive charge was 600 kg. But in fact, he mistook the weight of whole bomb for the weight of explosive charge. Since then, many historian quoted the information.

Ryusuke

 

[moin1900]

The japanese "Rammer"
How should it take-off ?
-with a trolley, like the the Shusui ?
-with a catapult or a ramp ?

Many greetings

 

[Pelzig]

How the rammer or, as I like to call it, the tai-atari (body crashing) plane, was launched is not known. It could have been catapult launched, as was vogue, perhaps trolley launched, air launched via towing, or even vertically launched.

The top speed of the rammer was 699mph which is into the transonic range (Mach .91) and I suspect the Japanese had very little experience with this realm of high speed flight and the problems it presents.

Cheers,

Ed

Hi everybody

The japanese "Rammer"
How should it take-off ?
-with a trolley, like the the Shusui ?
-with a catapult or a ramp ?

Many greetings
moin1900

 

[ryusuke]

Considering the rammer had no landing gear and its rocket engine had very short burning time (9 to 10 seconds), it is natural that rammer would be launched by catapult like other rocket/jet aircraft in the end of the war. Japanese knew the information of Natter, German intercepter, so there is possibility that the rammer would be launched vertically.

As for high speed flight, the official information tells that the Japanese was having the research of high speed flight and the wing appropriate for the speed.

HTH
Ryusuke

 

[moin1900]

Thanks for the replies ! I think the VTOL (NATTER) variant could be a good solution !

Many greetings