Upper Limits of Imperial Japanese Aerospace Technology

[GrauGeist]

In regards to Japan and German technology, their Nakajima Kikka and KI-201 were reverse engineered examples of German plans, as the subs transporting the actual unit and blueprints were sunk.

So, yes, the concept was German, but their engineering ability allowed them to create their own version based on photographs.

There was also the Yokosuka MXY-7, which was a native design.

The Japanese were also working in a native Surface to Air missile program, cide named "Funryu", who's development was too late in the war to be of use.

There was also the "Ke-Go" project, which was a guided weapon being developed by Yokosuka late in the war.

Kawasaki was developing a radio guided Air to Surface missile late war, the KI-147 and the KI-148, both if which were not fully developed by war's end.

 

[Shortround6]

There was a lot of 'stuff' that was not fully developed at the end of the war, in a number of countries.
Granted in 1946-48 weapons development slowed down a lot. Starting speeding back up in 1948-49 and with the Soviets exploding their own atomic bomb in Aug 1949 things like guided missiles got a lot more funding. Nike Ajax didn't become operational until March of 1954.
Germans had experimental anti-tank missile in 1944/45?
First operational anti-tank missile was the French SS.10 in 1955

They started work in 1948.
The history of something that should have been 'simple', The MG 213 revolver cannon took until the early 50s to get into production.

The problem wasn't with the basic concepts, it was turning those concepts into reliable (somewhat) working hardware. Granted peacetime standards were somewhat higher than wartime standards. Then you have to actually produce the stuff in large quantities.
See US M23 .50 cal incendiary ammo, that took from 1944 to well into the Korean war, and they may not have gotten the reliability they wanted even then.

Kudo's for thinking outside the box but just about everybody (or everybody) under estimated the amount of work needed to get some this stuff work even a majority of the time.

 

[JoblinTheGoblin]

I've seen varying figures for the speeds of wartime jet fighters, but the Ne-130 (>900kg thrust SL) engined Ki-201, and its comparably diminutive Ne-230 (~<890kg thrust SL) counterpart, may have been inferior to its hypothetical opponents, the Meteor and the P-80, in terms of level flight speed and rate of climb, though I'm not sure. The Yokosuka MXY-7, with its rather, to put it politely, 'guerilla' guidance system, was a dead-end technology, a straight-line 'aircraft' that was slower than the best Allied propeller interceptors. It's general concept was inspired by the V-1 missile, though I'll give credit here and say that it, alongside with the Ki-201 and Kikka, were all indigenous Japanese aircraft in practice.

Now, for the limits of Japanese technology in other areas of flight; wartime Japanese propeller engines. The most powerful envisioned was the 36 cylinder 5000 HP Ha-54, 5000HP at take-off, intended to be used as the power plant of the Nakajima G10N Fugaku intercontinental bomber, which, according to rather optimistic estimates for the version with six Ha-54 engines, would have been one of the fastest and most powerful— in terms of both payload and engine power—heavy bombers of the era, comparable with contemporary jet bombers. Issues with cooling, and potentially problematic maintenance with its relatively complex design, doomed the engine before a prototype was ever constructed, and it was substituted with a weaker, less complex engine. Notably, it apparently would have driven contra-rotating propellers.

The most powerful indigenous single Japanese liquid-cooled engine appears to have been the "Ken No. 2" (YE3E/Ha-74-11?), . There is no evidence that it was completed in any tangible form, and I have not seen any mention of any potential applications in any aircraft. Like the Ha-54, it was designed to drive contra-rotating propellers. It's comparable to the Ha-201 engine, a combination of a liquid-cooled, German licensed Ha-40 pair, intended to power the relatively fast Ki-64 heavy fighter, though issues with cooling would also damn this idea to irrelevance.

It seems as if the Mitsubishi Ha-50 was the most powerful Japanese radial engine design, with >3100HP/2600rpm, but the cancellation of the Kawanishi TB long-range bomber project, which was to utilise the engine in flight, in favor of the Fugaku, meant that development on the engine was all but abandoned. The earlier (1942) Ha-46 engine, if Japanese Wikipedia is to be believed was similarly powerful, with 3000HP/2600rpm at take-off, but teething problems led to adoption of the Homare engines instead. The Ha-46 would be briefly considered for use in the Ki-87 towards the war's end. On a side note, latewar Japanese warbirds like the Ki-87, Ki-94-II, and J7W, seem comparable to the aircraft of other nations at high altitudes—at least in terms of weaponry and maximum level flight speed, barring the likes of the Ta-152, though their times to reach altitude(s) are, along with their overall manoeuvrability, questionable. With the worsening war situation, if they ever flew, they likely would have never achieved their estimated performances.

Supposedly, there existed a Mitsubishi Ha-53 engine, potentially more powerful than the Ha-50, with 3400HP/2800rpm at take-off, but information on this engine is difficult to come by, aside from it having being considered as a power plant to drive the long-range Ki-91 bomber.