Japanese Design Philosophy

[NevadaK]

It does appear to be the case, for the most part, that Japanese aircraft have larger wing areas that would incur more drag. I've seen this and other similar design choices attributed to a sort of 'manoeuvrability mafia', at least in the IJA, that overruled more technically advanced designs like the Ki-11 (Japanese Peashooter, essentially), Ki-12 and Ki-28 in favour of slower but more manoeuvrable designs like the Ki-10 and Ki-27. The Ki-11 at least appeared to suffer from a slower rate of climb than the Ki-10, but was otherwise more efficient in terms of level speed at altitude. Finding data online for the Ki-12, and for any early-war (or even late-war, as I will get into later) Japanese prototype is not trivial, but it apparently possessed a 20mm cannon, and in addition to the usual 7.7mm pair? The Ki-12 was also Western-designed, requiring a Western liquid-cooled engine like the later Ki-28, and the IJA understandably did not want to rely on foreign licensed engines. The Ki-28 was, though another less manoeuvrable design, faster and could climb higher than most variants of the Ki-27, if any ever did exceed it in these metrics Another issue arises then with the Ki-18, superior to the Ki-10 in nearly all aspects save perhaps turning times or low-speed roll rates. It was a proposal to the IJA derived from an IJN design, the A5M. No need to say much more than that. Supposedly, though I've long forgotten the source of this information, a main concern of the "manoeuvrability mafia" was countering biplane designs that were more common in nearby China, and if that was the case, perhaps a more powerful China (say, earlier unification under the Zhili clique?) would have changed their minds, if slightly. This type of opponent may have contributed to a preference for manouevrability amongst the pilots as well, though I'm not entirely sure. There's some bits of information here and there on this forum that pilots were anxious about the manouevrability of the Ki-43 when it was initially put into production and how even as speed became a more serious issue later in the war, manoeuvrability was apparently still important for Ki-43 pilots when it came to surviving BnZ opponents, something the Ki-84, from first-hand accounts on both sides fast enough to avoid the P-51 / F4U(?) (at low-mid altitudes?), was claimed to have been more vulnerable to thanks to its lesser manoeuvrability.

The main issue with assessing late-war Japanese aircraft performance is a lack of detailed data, especially power curves and the like. For instance, the level speeds of aircraft like the Ki-87 and the aforementioned Ki-83 are given at altitudes above 10000m (>32000ft), and vary between ~680kph (422mph) and <710kph (441mph). Worse, I've seen a slower figure outside of that range given for the Ki-83 at around half the altitude (supercharger, maybe, if the figure's to be believed). I can't say much more than this right now.

I was trying to locate a direct reference, but I've seen in numerous texts the observation that Japan's Bushido Code influenced Japan's thinking about combat and the design of weapon systems like aircraft. There was a tendency to think of aerial combat as "man to man" and "to the death", hence the Japanese design emphasis on dogfighting maneuverability rather than less honorable tactics like boom and zoom. This article doesn't address that directly, but does providing some great insights.

Silver Bullet Blunder | Air & Space Forces Magazine

Imperial Japan committed a startling number of airpower stupidities.

www.airandspaceforces.com

Kk

 

[Shortround6]

Does anybody have translations of actual Japanese texts, statements, policy, theory or tactics?
Or any Japanese speakers/readers run across anything?

There has been a crapload of misinformation put out about allied aircraft and air doctrine/theory's for the last 80+ years. And most of us can read English/American
The P-40 being designed for low altitude strafing being one. It was fitted with the best high altitude engine the Army could get in summer/fall of 1940.
The two points of view do NOT crossover well.

Maybe the Japanese did believe in the power of maneuver, But they were not the only ones. Italian fighters of 1938-40 anyone?
Soviets first flew the I-153 biplane in 1937. Started production in 1939 and they built 3,437 of them before they stopped.
Soviets believed in a Soviet version of Bushido and "man to man" aerial combat?

When does the Bushido code takeover from combat tactics/experience.
Japanese had been fighting in China for for most of the 30s (since 1933?) and the Italians and Soviets had fought each other in Spain for several years.
The Japanese liked maneuverability and tried to combine maneuverability with speed (monoplanes) while the Italians and Soviets tried to hedge their bets
and built both types at the same time and hoped they had the correct aircraft in the correct part of the sky at the correct time they were needed.

Trying to figure out an air forces psychology based on the hardware they produced is very hard game.
We would also need to separate out what they actually wanted vs what they could actually produce and how much compromise there was between the two.

Much like the USAAF wanted fighters that could fly/fight at 25,000-30,000ft + in 1937-39. But they knew the hardware ( engines and turbos) would not be available until 1941/42.
You need fighters in service squadrons in 1940-41, what do you choose?

 

[AerialTorpedoDude69]

I was trying to locate a direct reference, but I've seen in numerous texts the observation that Japan's Bushido Code influenced Japan's thinking about combat and the design of weapon systems like aircraft. There was a tendency to think of aerial combat as "man to man" and "to the death", hence the Japanese design emphasis on dogfighting maneuverability rather than less honorable tactics like boom and zoom. This article doesn't address that directly, but does providing some great insights.

Silver Bullet Blunder | Air & Space Forces Magazine

Imperial Japan committed a startling number of airpower stupidities.

www.airandspaceforces.com

Kk

That's a well written article but it reads like propaganda. In some ways it oversimplifies certain aspects of the political and economic conflicts that occurred during the lead up to the war. It also relies on stereotypes to explain the expansionist logic used by (according to Robert Mearsheimer) "revisionist" states, countries that seek to upset the status quo through military expansionism. Most scholars don't bother using culture to explain state behavior. The most common method of analysis is to anchor political decisions in Realpolitik. In practical, material and strategic terms.

But getting back to "bushido" logic, I would argue that very few rank-and-file soldiers were guided by bushido. Saburo Sakai, as is obvious from his own records and from the records of those who fought against him, was guided by such principles. He was, after all, descended from a Samurai family. He had such values instilled in him from a young age. And he was a humanist.

The political leadership of Japan was another kind of person. Technocratic and interested in the economic picture. They made decisions based on the availability of resources. The Zero is a good example of a fighter made as a compromise between economic and military requirements.

Does anybody have translations of actual Japanese texts, statements, policy, theory or tactics?
Or any Japanese speakers/readers run across anything?

Great question and it fully answers the primary topic regarding Japanese design philosophy.

In Horikoshi's Eagles of Mitsubishi he clearly states that the military wanted it all, but because aircraft design is one of compromise, they had to settle on a lightweight fighter because the military wanted to use a lightweight engine in its fighters. Horikoshi may have mentioned that the heavier engines were used in strike and bomber aircraft.

 

[NevadaK]

Does anybody have translations of actual Japanese texts, statements, policy, theory or tactics?
Or any Japanese speakers/readers run across anything?

There has been a crapload of misinformation put out about allied aircraft and air doctrine/theory's for the last 80+ years. And most of us can read English/American
The P-40 being designed for low altitude strafing being one. It was fitted with the best high altitude engine the Army could get in summer/fall of 1940.
The two points of view do NOT crossover well.

Maybe the Japanese did believe in the power of maneuver, But they were not the only ones. Italian fighters of 1938-40 anyone?
Soviets first flew the I-153 biplane in 1937. Started production in 1939 and they built 3,437 of them before they stopped.
Soviets believed in a Soviet version of Bushido and "man to man" aerial combat?

When does the Bushido code takeover from combat tactics/experience.
Japanese had been fighting in China for for most of the 30s (since 1933?) and the Italians and Soviets had fought each other in Spain for several years.
The Japanese liked maneuverability and tried to combine maneuverability with speed (monoplanes) while the Italians and Soviets tried to hedge their bets
and built both types at the same time and hoped they had the correct aircraft in the correct part of the sky at the correct time they were needed.

Trying to figure out an air forces psychology based on the hardware they produced is very hard game.
We would also need to separate out what they actually wanted vs what they could actually produce and how much compromise there was between the two.

Much like the USAAF wanted fighters that could fly/fight at 25,000-30,000ft + in 1937-39. But they knew the hardware ( engines and turbos) would not be available until 1941/42.
You need fighters in service squadrons in 1940-41, what do you choose?

Thank you, Shortround6,

I'm not a big fan of identifying "culture" as a reason for the way things are, especially when this can lead to bigoted thinking and all that entails. I do think that every nation has periods where a clearly defined cultural outlook is adopted resulting in a zeitgeist through which decisions or heavily filtered. Japan of the early 20th century fits this model especially with the role the military played overall in society. How much that influenced the design of aircraft is, I grant you, open to conjecture. That said, the emphasis of maneuverability in Japanese aircraft design does imply that there was an underlying concept about air combat that valued that over other qualities. If that is because the Japanese military's adoption of bushido as a principal, that would make a certain kind of sense. But, I'm not able to back that up with specific citations. Just a recollection that I have seen that premise in a number of past sources.

 

[Shortround6]

For the next 'generation' of JAAF fighters we had the Ki-10

Which is pretty obviously a modification or perhaps continuation of the thought process of the previous Kawasaki Biplane.

Wing area 215-250 sqft depending on version
gross weight 1650-1740kg( 3638-3836lbs)
wing loading 16.9-15.3lbs/sq/ft
engine 850hp
2 7.7mm machine guns (Vickers)

top speed 248mph
endurance range 684 miles
ceiling 10,000 meters to 11,500 meters depending on wing size.
time to climb 5000 meters in 5 minutes.
During the trials with first aircraft it was feared that the prototypes were too slow against the Ki-11 monoplane and Kawasaki fitted a 3 bladed propeller and used flush rivets which cut the margin of difference down but did not eliminate it. Common photos of KI-10s with spatted undercarriage are from a later improved version/s that were not adopted.
Using an 850hp engine instead of a 550hp engine certainly helped the speed.

The Ki-11 was the unsuccessful contender, 4 built

Wing area 205 sqft
gross weight 1269kg( 3440lbs)
wing loading 16.7 lbs/sq/ft
engine 550hp
2 7.7mm machine guns (Vickers)

top speed 262mph
endurance range 250 miles
ceiling 10,200 meters
Said to be inspired by the P-26 but once you decide on a low wing monoplane with bracing wires, a spatted undercarriage and a radial engine the appearance is already mostly decided on.
Now please note that in this case the speed margin was only about 5.6% and the maneuverability may depend on airfoil/controls as much as the wing area. The first 300 Ki-10s built had the smaller wing.

This sets things up for the 3rd generation, The Ki-12 and Ki-18 and the navy/army rivalry/hatred rears it's head.

In the next post.

 

[SaparotRob]

Looking forward to the next installment!

 

[GrauGeist]

The USAAC's P-36 was extremely maneuverable and this was a key feature that the Germans learned the hard way when they encountered French Hawk 75s during the Battle of France.

 

[bf109xxl]

Soviets first flew the I-153 biplane in 1937. Started production in 1939 and they built 3,437 of them before they stopped.
Soviets believed in a Soviet version of Bushido and "man to man" aerial combat?

The I-153 project (i.e., "I-15 modification 3") was approved in November 1937, and the first flight took place in August 1938; serial production did not begin until spring-summer 1939. The delay in serial production of the I-153, even for the Soviet system, is quite unusual and can be explained only by a rare confluence of circumstances - both typical for Soviet aviation at the time (delay in engine development) and atypical (relocation of the Polikarpov's design bureau, complicated relations with the GAZ No. 1 design bureau, which did not pay attention to the preparation of the I-153 production, being engaged in supporting the production of the I-15bis). There were certain rational arguments in favor of I-153 production - even in 1939, when the combat results of the I-153 in Mongolia were considered as quite satisfactory - but not in 1940! In general - the Soviet system was extremely inflexible and inert due to the low educational level of responsible officials and negative selection for leading positions. This is the answer to the most of the "why?" questions in the Soviet history.

 

[Shortround6]

Some of the numbers here seem to be in order of start of the project. Not first flights.

The Ki-12 was Nakajima project that was overseen/helped by a couple of Dewoitine engineers.

Wing area 183 sqft
gross weight 1900kg( 4189lbs)
wing loading 22.9 lbs/sq/ft
engine 610hp H-S Xcrs engine
one 20mm cannon and 2 7.7mm machine guns (Vickers)

top speed 300mph
range 500 miles
ceiling 10,500 meters

Some of the performance numbers may be estimates. While fast it was not liked by the army due to complication/expense and lack of maneuverability. Depending on a licensed engines (or having to tool up for it) was also suppose to have counted against it. The story goes that the 2nd airframe was completed as the Type P.E. fixed landing gear and radial engine.

Meanwhile Mitsubishi was working on the Ka-14 19-Shi for the Navy starting in 1934 and flying Feb 1935, The 2nd prototype got rid of the gull wing

and formed the start of the A5M navy series fighters, but Mitsubishi also pitched the plane to Army as the Ki-18 and the Army bought one.
engine was changed at least once.

Wing area 192 sqft
gross weight 1422kg( 3135lbs)
wing loading 16.3 lbs/sq/ft
engine 715hp Kotobuki 3 (last engine)
2 7.7mm machine guns (Vickers)

top speed 276mph
range --- miles
ceiling --- meters

The Army flying school was very much in favor of it but the Army Air Technical Research Institute was very much against it, including claiming that the Kotobuki engine was unreliable.
In any case they wanted a new competition that lead to the Ki-27

Wing area 200 sqft
gross weight 1790kg( 3946lbs ?)
wing loading 19.7 lbs/sq/ft
engine 710hp Kotobuki (early engine)
2 7.7mm machine guns (Vickers)

top speed 292mph
range 390 miles
ceiling --- meters
The P.E. and Ki-27 used new light weight construction and a new airfoil section. Of interest is that the first Ki-27 prototype used a 176.5 sq ft wing and the 2nd used a 189.4 sq ft wing.
The speed difference between the two was 7kph (4.35mph), the preproduction trials and production aircraft used the 199.777 sqft (200) wings of about 3 ft more span.
The Ki-27 prototypes were tested against the Ki-28 and the Ki-33

Wing area 200 sqft (wing is over 2 ft greater span)
gross weight 1760kg( 3,880 lb ?)
wing loading 19.4 lbs/sq/ft
engine 800hp Kawasaki Ha-9-II
2 7.7mm machine guns (Vickers)

top speed 301mph
range ---miles
ceiling 11,000 meters

The Mitsubishi Ki-33 was just a mildly updated Ki-18/A5M

Wing area 192 sqft
gross weight 1462kg( 3223lbs ?)
wing loading 16.7 lbs/sq/ft
engine 746hp Kotobuki (early engine)
2 7.7mm machine guns (Vickers)

top speed 295mph
range ---miles
ceiling --- meters

This pretty much ended this line of development with the Ki-43/Ki-44 and Ki-60/61 being the next generation. Ki-43 was sort of in-between but was running late (due to insistence in maneuverability.) and they had under 1/3 as many Ki-43s as they did A6Ms at the end of 1941. 1942 wasn't much better with just over double the number of A6Ms built as Ki-43s.

 

[nuuumannn]

The problem with making comparisons between each country's machines is that we have access to information today that the designers or intelligence personnel could not have had back then. Before the war there wasn't very much sharing of intelligence, although it did happen. A few European aircraft manufacturers including Britain shared technology with Japan, but after that country's increasing militaristic stance and its invasion of China, those countries, with the exception of Germany shied away from Japan as an ally. This meant that it received technological assistance from Germany, but it developed its own eco system of design and supply of military equipment that existed in something of a bubble, isolated from the rest of the world, which was deliberate, of course. The Japanese military industrial complex model was different to Europe and the USA, which notably resulted in a unique approach to aircraft philosophy, design, manufacture and influence.

Before we lean too heavily in the direction of the Japanese workforce producing crude and less sophisticated designs, that simply wasn't true. Investigation of Japanese aircraft designs during the war prove this as a fallacy. I have yet to read one that criticises the production values of Japanese aircraft. Yes, things like engine power and armament lagged behind the west, but that was a matter of resources and an internal government and industry deficiency in the appreciation of the evolving battlefield and their reluctance to address it, rather than a lack of sophistication and ability.

The Mitsubishi Zero is a classic example of this entire scenario. The Zero was finely designed and built and technologically was a match for its carrier based contemporaries in terms of technological advance and performance back in 1939/1940 when it went into production and service. It had modern systems, flaps, retractable undercarriage, cannon armament when none of its contemporaries did, intricate design features, such as its means of entry into the cockpit for the pilot, for example, a series of retractable pegs to avoid the pilot standing on the wing root. These pegs sat flush with the fuselage side, and extended when a lever was pulled, which in turn sat flush with the aircraft fuselage. These pegs retracted into the fuselage and had small mushroom shaped inner ends, this was because where they retracted into was kept a floatation bag that deployed automatically when the aircraft ditched. The mushroom ends ensured the packed bag did not get punctured by the moving pegs.

The pegs extended.

NX712Z 12

The entire aircraft was cleverly and sensibly designed, and when an analysis of its design is made, it compares favourably with its contemporaries as an entirely modern, well designed and constructed aircraft. That it outlived its usefulness and was kept in the frontline far longer than it should have been, thus exposing its deficiencies, which were not apparent when it was first introduced, was not the aircraft's doing, but the naval high command's fault. Focus was taken away from its replacement on carriers, not to mention the Japanese naval high command believed their own hype surrounding the aircraft for far too long, and steered its designers toward land based interceptors rather than carrier based ones following extensive carrier losses at Midway. The Mitsubishi A7M, Horikoshi's intended A6M replacement suffered delay after delay and because of mounting defeats as the war wore on Japan's industry simply could not keep up with the evolving strategic scenario, so the poor Zero stayed on amid a scramble to produce anything that matched what the West was fielding.

Read this report for a good insight into the design produced by a US aviation publication during the war.

Design Analysis of the Zeke 32 (Hamp - Mitsubishi A6M3)

Japan's fate was linked to Germany's - it simply could not match US manufacturing and logistical might and Allied technical knowledge sharing, it had nothing to do with technological inferiority. The Imperial government's lack of appreciation of what it had got itself into was disastrous and ultimately led to Japan's defeat on the many battlefields it was engaged on, regardless of how bloody they were. As with all dictatorial regimes, there was a detached reality between what was happening on the intelligence summaries the masters read every morning and what was happening on the battlefields. Japan's soldiers were fierce, loyal and determined, but their masters failed them by grossly underestimating the US/Allied resolve, manufacturing capability and sharing of technology.

Japanese industrial structure also hampered its war effort. The Army and the navy had its own industrial bases, factories, plant, such as steel mills and so forth, and so, like Nazi Germany, backstabbing, undermining the opposition and outright subterfuge to curry favour with government institutions hampered the overall industrial output, long after the Allies had figured out that total war required working together on a scale that was previously unheard of. Japan lost because of this, as did Nazi Germany, for that matter. Both failed to realise that the very systems they operated under were detrimental to their own war effort.

The sharing of technological advance and resources between the USA, UK and their Allies was unprecedented in history. The Axis powers never reached such heights to the same degree. A handful of jet engines via U-boats to Japan and what have you doesn't match anything like the exchange of equipment that went around the globe from the USA and to a lesser extent Britain. Had Japan's separate naval and army industries worked together, things might have taken longer for the Allies to defeat Japan and those weapons and aircraft that we regard as inferior probably would have been more on a par with what the West was producing, but let's be clear, this lack of capability by comparison with Western aircraft and engines does not indicate a weakness within the Japanese technical know how, but a weakness within Japanese appreciation of the strategic situation. The country's engineers and designers were as capable as those anywhere else, its just they were let down by the unique set of circumstances that Japan existed in, not technological inferiority.

Understanding this places Japan's technological output into context. Japan had the knowledge, it had knowledge of and even implemented some of the same advances the West made on its aircraft, such as superchargers, armour plating, self-sealing fuel tanks, greater engine capacities and so forth, but much later than the Allies, simply because they didn't have the same intel network and willingness to share information among its industry for the greater good. As previously mentioned, a lack of appreciation of the evolving strategic situation and the unique Japanese wartime environment defeated its engineers, which actively hindered the entire nation's technological progress. The ideas were there, though.

 

[Shortround6]

Before we lean too heavily in the direction of the Japanese workforce producing crude and less sophisticated designs, that simply wasn't true. Investigation of Japanese aircraft designs during the war prove this as a fallacy. I have yet to read one that criticises the production values of Japanese aircraft. Yes, things like engine power and armament lagged behind the west, but that was a matter of resources and an internal government and industry deficiency in the appreciation of the evolving battlefield and their reluctance to address it, rather than a lack of sophistication and ability.

There is a lot in what you say not only here but in the rest of your post.
It may also be that the Americans, British and Germans accelerated their production capabilities during the war years (counting war years as 1939 and on even for the Americans) and 1935-36 western engines were not that far ahead of Japanese engines in build quality or sophistication, at least in radials.
There were major exhibitions in European countries during the 30s to drum up trade and perhaps (more than perhaps?) show off, intimidate potential opponents. Engines and aircraft were on display in exhibition halls. Now how they were built may have have been secret but shapes, trends, advertising claims were available to anybody with the price of ticket in their pocket. In the fall of 1938 the Spitfire and Hurricane were on display along with at least one Merlin on a stand. Do-17 bomber was in the same hall. Aircraft performance figures were not.
The Japanese Nakajima Kotobuki engine may have been a very nice, up to date 9 cylinder radial engine in 1936-38. But part of it's trouble was that it was a 24.1liter (1471 cu in) engine when the British were using the barely larger Mercury (but at higher RPM) and the Pegasus. P&W was already giving up on the 27.1 liter Hornet to build the 30 liter twin wasp (R-1830). Wright was exporting 30 liter Cyclones all over the place and licensing them in several countries.
Nakajima did use the Kotobuki size cylinders in the Ha-5, Ha-41, Ha-109 series engine (37.5 liters) but for some reason it seems to be running late (low power and/or low rpm).

The Japanese may not have had access to how something was done (for engines that may be more material/alloys and processes rather than specs on paper) but were the Japanese smarter than everybody else by sticking with fixed landing gear or were there other reasons? Lack of capability to build enough hydraulic cylinders? or light enough? More expensive planes means less planes while fighting the war in China (and the Russians?). They might have had very valid reasons. But those reasons may not be the ones often published in western books.
Why were the Japanese radials operating 2-300 slower than the British/American radials at certain times? Japanese are not stupid. Perhaps they don't have the steel alloy for the crankshaft/connecting rods? or bearings? or perhaps they cannot make the cylinder fins of the size needed to cool the engine at the higher power?
Wright changed the cylinder fins on the R-1820 at least 5 times during 1930s to improve cooling. many times had to change the tooling to do it.

 

[Howard Gibson]

I was inspired to make this post, having heard of the exemplary record of the Ki-43, and claims that the Ki-100 had similar characteristics to more advanced aircraft like the Merlin-powered P-51 in nearly all aspects of manoeuvrability except, oddly enough, level flight speed, and maybe some other metric I haven't mentioned here.

Was the Ki43's record exemplary?

The Japanese wanted manoeuverability, so they built aircraft that were lightweight. Manoeuverability was important in WWI. Over the next twenty five years, aircraft became something like three times faster. There were no comparable improvements to the guns other than they got bigger. Gun ranges were about the same in WWII, so hit and run tactics worked for fast, heavy aircraft. Homing missiles make manoeuverability important for modern jet fighters.

The British and the Americans anticipated the need for 2000HP engines. The Pratt and Whitney R2800 was thoroughly debugged by mid-war and it powered all sorts of big, versatile fighter aircraft. The British got 2000HP out of Napier Sabres and Rolls Royce Griffons, although none of these reached the east to face the Japanese. The Bristol Centaurus mostly missed the war.

The Nakajima Homare engine produced almost 2000HP with water methanol injection turned on. It was a surprisingly small engine, 36litres, versus the 46litres of the P&W R2800. Successful WWII radial engines were big.

Lacking really big engines, the Japanese did not have the option of designing fighter bomber aircraft like Corsairs, Hellcats, and Thunderbolts.

 

[Shortround6]

Over the next twenty five years, aircraft became something like three times faster. There were no comparable improvements to the guns other than they got bigger. Gun ranges were about the same in WWII, so hit and run tactics worked for fast, heavy aircraft.

Actually the effective range of the guns (but not the sights) increased for the better guns by 50-100%. Using WW I guns/ammo in WW II aircraft did decrease the air craft effectiveness.
The use of 20mm exclusive ammo radically changed the close range fire power. Even WW I airplanes sometimes withstood several dozen 7.7-7.9mm hits.

The Nakajima Homare engine produced almost 2000HP with water methanol injection turned on. It was a surprisingly small engine, 36litres, versus the 46litres of the P&W R2800. Successful WWII radial engines were big

The Japanese were playing catch up. The Homare and R-2800 could both give 2000hp at sea level/take-off. The R-2800 could do it the spring of 1942. In the fall of 1944 the R-2800 was good for 2000hp at 18,000ft in a Corsair using water injection. It was good for 2250-2300hp at sea level. P-47s were good for over 2500hp using water injection.
Not getting into the "C" series R-2800s.

The Japanese had the 1450hp Ha-109 engine in the spring of 1942, They chose not to use it in a fighter bomber. (See Hurricane IIs and P-40s for under 1500hp fighter bombers) or see the Mitsubishi Kasie engine. Somewhat comparable to the Wright R-2600 except lighter.
Engine designs were available, manufacturing capability may not have been.

 

[JoblinTheGoblin]

Was the Ki43's record exemplary?

According to this thread, the Ki-43 was dong somewhat well against otherwise faster aircraft like the P-51A and P-38, could shoot down medium-heavy bombers even with its relatively light guns, and, especially in the hands of capable pilots, could still shoot down or damage other more advanced fighters. Even its naval counterpart was apparently neck to neck with the F4U out in the Pacific mid-war. To add, apparently, an adept pilot could use the Ki-43's low-speed manoeuvrability to better evade BnZ aircraft, something the faster and more powerful Ki-84 was reportedly worse at, given that aircraft's lesser manoeuvrability.

Judging from the course the thread's gone down, I think I'll hold off from adding to the discussion any further until I get some actually 'good-quality' sources, if I have the time or will to do so.

Edit: I'll still update the OP from time to time whenever the thought crosses my mind.

 

[tomo pauk]

The British and the Americans anticipated the need for 2000HP engines. The Pratt and Whitney R2800 was thoroughly debugged by mid-war and it powered all sorts of big, versatile fighter aircraft. The British got 2000HP out of Napier Sabres and Rolls Royce Griffons, although none of these reached the east to face the Japanese. The Bristol Centaurus mostly missed the war.

Japanese also anticipated the need for 2000 HP engines. Due to their engine companies indeed playing catch-up, they started making the 2000 HP engines by late 1943/early 1944, ie. some 2 years past the USA or UK.
What the Japanese missed was the perceived notion that 1100+- HP engines are worth it in the 1st line aircraft, even in 1944. These took up a good chunk of production capacity, meaning that there was less resources left for the 1500+ HP engines to be made, let alone 2000 HP types.

Add the whole host of dubious purchase decisions, and Japanese were up the creek without the paddle, despite the good/very good engines they made. And that is before we address the US/Allied manpower and manufacturing abilities advantage.

The Nakajima Homare engine produced almost 2000HP with water methanol injection turned on. It was a surprisingly small engine, 36litres, versus the 46litres of the P&W R2800. Successful WWII radial engines were big.

American small radials were very successful in powering the aircraft that blunted the Japanese military power in 1942. British small radials were succesful in trashing the Italian Navy.
German 1600 HP radials were powering possibly the 1st German aircraft that stopped the Spitfires cold, so perhaps 2000 HP was not all that needed?

Lacking really big engines, the Japanese did not have the option of designing fighter bomber aircraft like Corsairs, Hellcats, and Thunderbolts.

They could've designed the fighter-bomber aircraft like that was the Fw 190, the 1500-2000 HP Japanese engines would've been doing great there. Even the Ha 109 powered Ki 61 would've been doing the trick. But, same as with the lack of long range high performance fighters for the RAF: no doctrine = no hardware.

 

[GrauGeist]

In regards to Japanese fighter-bombers, several types were equipped to carry bombs if needed.

It seems that the Japanese preferred to use types specifically designed for attack rather than use fighters in this role.

Here are the types that could:
KI-100 - 2x 550 pound bombs
J2M - 2x 132 pound bombs
N1K1 - 2x 550 pound bombs
KI-84 - 2x 550 pound bombs

 

[Shortround6]

According to this thread, the Ki-43 was dong somewhat well against otherwise faster aircraft like the P-51A and P-38, could shoot down medium-heavy bombers even with its relatively light guns, and, especially in the hands of capable pilots, could still shoot down or damage other more advanced fighters

The author of that thread may be somewhat partisan. He is no longer with us and I will not say more than that. I have used a US baseball analogy before. In a 162 game season, most years, every team will win 60 games. Every team will loose 60 games. The difference between 1st and last place in league is 42 games. Any team has the possibility to beat any other team on a given day, even the last day. Japan needed better than a near last place fighters in 1943-44-45.
It was possible for Ki-43s to shoot down US medium-heavy bombers. But a standard tactic was to use 3 or more planes to attack a single B-24 in a formation and to make repeating firing passes on the same plane. A more well armed interceptor may have required few planes or firing passes to get the same result which could mean more allied bombers shot down in the the same number of engagements. The Ki-43 had the least amount of firepower of any fighter used numbers (more than a few dozen) in 1943 let alone 1944.
They built 3500 of them in 1944-45, which is well past their "best use by" date. One is entitled to wonder if the Japanese would have been better served by 2500-2800 1400-1500hp fighters with four 12.7 guns or even two 12.7 and four 7.7mm guns.

Even its naval counterpart was apparently neck to neck with the F4U out in the Pacific mid-war.

F4U showed up in Jan 1943, by early July there were 8 Marine squadrons operating in the Solomon's.
There were no carrier to carrier battles in all of 1943.
The Zero was in no way, shape or form capable of fighting the F4U on a squadron to squadron (team to team) basis. Zero's shot down F4Us but much more often than not they came out on the loosing end or were not able to keep the F4Us and other US fighters from shooting down numbers of bombers.

To add, apparently, an adept pilot could use the Ki-43's low-speed manoeuvrability to better evade BnZ aircraft,

Evading means surviving. Surviving means living to fight another day, it does not mean that todays mission was successfully accomplished.
Were the enemy bombers shot down or forced to turn back?
Were significant losses inflicted on the enemy escort fighters?
Did your own bombers reach and engage their targets?
Were significant losses inflicted on the enemy intercepting fighters?

Now if you can use the superior maneuverability to quickly re-engage and damage/destroy the enemy aircraft to prevent them from accomplishing their mission then great.
But the Ki-43 and Zero often could not as the war went on.

 

[Howard Gibson]

American small radials were very successful in powering the aircraft that blunted the Japanese military power in 1942. British small radials were succesful in trashing the Italian Navy.
German 1600 HP radials were powering possibly the 1st German aircraft that stopped the Spitfires cold, so perhaps 2000 HP was not all that needed?



They could've designed the fighter-bomber aircraft like that was the Fw 190, the 1500-2000 HP Japanese engines would've been doing great there. Even the Ha 109 powered Ki 61 would've been doing the trick. But, same as with the lack of long range high performance fighters for the RAF: no doctrine = no hardware.

The small American radials coped with the enemy. Everybody had the same sized engine up into 1943. By 1943, the 2000HP American aircraft were faster, they had armour protection, and they could carry significant bomb loads. Getting late war Zeroes up to 350mph was a remarkable accomplishment for the Japanese, but the enemy was doing 390mph+.

The small British radials were in biplanes, right? Gloster Gladiators did well against FIAT Cr42 biplanes. The Fw190 had a 42liter engine.

 

[Shortround6]

American small radials were very successful in powering the aircraft that blunted the Japanese military power in 1942.

Yes and no. Pretty much, at least for fighters, only the navy/marines were using radials (pretty much only the R-1830).
However the Allison was doing a lot work blunting Japanese air power in 1942 most places there were land bases.
British were feeding in Merlin powered Hurricanes for fighters in Burma/India, Not sure how much they blunted the Japanese but they did put some wear on them

German 1600 HP radials were powering possibly the 1st German aircraft that stopped the Spitfires cold, so perhaps 2000 HP was not all that needed?

Again yes and no. The 1600hp radials stopped the Spitfire Vs cold in late 1941 and over 1/2 of 1942. The Spitfires warmed up quite a bit in late summer of 1942/Winter of 42-43 with the MK IX and higher boost on the MK Vs.

The small American radials coped with the enemy. Everybody had the same sized engine up into 1943. By 1943, the 2000HP American aircraft were faster, they had armour protection, and they could carry significant bomb loads

See above. The US Army was NOT using small radials in fighters in SE Asia/Pacific, at least not after around March of 1942. Granted the Allison was about a (officially) 1200hp engine (give or take) but the V-12s allowed for higher speed (20-30mph or more?)in the P-39s/P-40s over the 1200hp radial fighters.

British small radials were succesful in trashing the Italian Navy.

Small radials in torpedo bombers. Small radials in fighters???

The small British radials were in biplanes, right? Gloster Gladiators did well against FIAT Cr42 biplanes. The Fw190 had a 42liter engine.

Both the British and Italians had radials of about 840hp at altitude, the Italian 14 cylinder was about a 31.4 liter engine. It was also under 570kg so it had limits.
The Gladiator had problems with even MC. 200 monoplanes. The Gladiator used a horribly out dated cowl but since there was so much drag in other places it probably didn't make much difference.

The FW 190 also was the first of the improved/low drag cowls/nacelles for radial engines, or at least the first of this generation of improvements. There had been several major advancements in cowl design from the 30s on. It was also among the first to really use exhaust thrust in a radial engine. Older cowl design and 'normal' single or dual exhausts out the side/bottom of the radial may mean you needed 1800+ hp to get that sort of performance.

The small american radials were doing good work in single engine attack aircraft, flying boats, light bombers. etc. However the US had shifted to 1600-1700hp engines in twin engine attack aircraft, light medium bombers even in early 1942 and B-26s were showing up with 1850hp engines by the summer of 1942.
Japanese didn't get to attack any B-18s or even B-23s.

 

[tomo pauk]

Yes and no. Pretty much, at least for fighters, only the navy/marines were using radials (pretty much only the R-1830).
However the Allison was doing a lot work blunting Japanese air power in 1942 most places there were land bases.
British were feeding in Merlin powered Hurricanes for fighters in Burma/India, Not sure how much they blunted the Japanese but they did put some wear on them

A definitive 'yes'.
American small radials powered the aircraft that sent the big chunks of the most potent Japanese naval force to the bottom of the sea before 1942 ended.

Neither Merlin nor the V-1710 qualify under 'big radials'.

Small radials in torpedo bombers. Small radials in fighters???

I'm not sure what the British (and other people's) fighters had to do with trashing of the Italian navy. FAA's torpedo bombers, powered by small radials, trashed the Italian ships in more than one occasion.
Small radials - not the big ones - were also the key players in catching the Bismarck.
Small radials were also key in closing the Atlantic for the U-boats.