Top 3 mistakes per country, in field of military aviation

#2: Hitler's declaration of war against the United States, the single greatest industrial power in the world, after the Japanese attack on Pearl Harbor in December 1941. On hearing the news, Churchill said he "went to bed and slept the sleep of the saved and thankful". It was poetic, but premature. It is ironic that Churchill's greatest Christmas present came from Hitler. Churchill said once the US was on board he knew Hitler was finished. After all, the Japanese attack indeed ensured that the US would go to war – but only against Japan.

Without Hitler's wholly gratuitous declaration, the Roosevelt Administration would never have persuaded Congress to go to war in Europe instead of focusing on the Pacific. And without US involvement, and knowing that the British could never have launched a D-Day type invasion on their own, the Germans could have kept a far smaller presence in France and would have allowed them to concentrate overwhelmingly on defeating the USSR. . However Hitler's War declaration assured that the entire population of the United States, under threat from the Japanese, was now also threatened by the Germans as well. Attacked on two sides the people of the US became single minded in their pursuit of victory over both aggressors. For the first time ever women entered the workforce in huge numbers and proved they could do a man's work. which would thereby have Once Hitler was forced to engage in monumental struggles for existence on both his eastern and western fronts simultaneously, the end was never really in doubt.

Shortround6 said:

Part of that may be fuel related. You need high performance number fuel for the two stage superchargers to work. Could the Germans plan on enough C3 fuel to go around? Coordinating fuel production and engine development might have been difficult.

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The only 2-stage supercharged engine in LW service, the Jumo 213E, was using 87 oct fuel.
Sure enough, the fuel of higher octane value will allow for better preformance under the rated height, The C3 fuel is already in production, having the Fw 190 with 2-stage engine that uses C3 fuel will mean more capability than the Fw 190 that has 1-stage engine and still uses C3 fuel.
Main reason why the DB 605L (a too late attempt on 2-stage variant) used both C3 and MW 50 (even for 'Kampflesitung, second highest power setting) was too high a compression ratio, while being without intercooler. CR being 8.5/8.3:1, vs. 6.5:1 for the Jumo engines (both 211 and 213).
The DB 603L (C3 fuel), once received intercooler (thus becoming 603LA) was cleared for B4 fuel.

Starting from my country, Poland :
1. A wishful thinking and overoptimistic expectations from a prototype of air-cooled inline engine "Foka" which could fulfill the requirements given the limited resources, scientific potential and several other factors which basically led to complete failure in deploying any new fighter in the second half of 1930s.
2. An incredibly wrong choice for a Chief of Department of Aeronautics and later Commander of Polish Air forces, which were given to general Ludomił Rayski. He put in favor bombers and heavy fighters effectively hampering any research for modern fighters. The only type of a fighter he tried to lobby for was PZL P.39 with very light airframe, 400+ HP engine Foka and two machine guns, trying to match Italian and French designs (like Caudron C.714). However as the engine turned out to be failure, the fighter could not be finished and was effectively rejected. PZL P.38 Wilk was impossible to be completed.
Eventually he commissioned a development of a new fighter, PZL P.50 but it was too late to complete the prototype, carry the trials and mass produce it. Fighter also presented a mediocre performance and flight characteristics due to inadequate engine power.
That's about it I guess. One could extend it to three, but really all the blame goes to inadequate funds and terrible Chief.

Japan :
a) Lack of co-operation between Army and Navy, both in development and combat. The first one went to such an extent that same manufacturers like Nakajima or Mitsubishi had to effectively split their teams and factories in order to keep secrets of one branch from the eyes of the other. This obviously slowed down any developments as less engineers could be assigned to specific tasks.
In case of combat co-operation I think best example of what if, could be an operation Ryu Ichi Go Sakusen - a joint strike against Calcutta in December 1943 when big formations of Ki-21s and G4M bombers were escroted by over 100 Ki-43s and 27 Zeros, such a projection of power was unusual for Japanese and caught Allies with "pants down" allowing to bomb Calcutta and prevent any interception of bombers. If Japanese would combine their limited air resources on crucial fronts the Allied offensive would take most likely a lot more time.

b) Initial negligence (?) in development of electronics and radars, with prime example of radio problems in early Zeros or Hayabusa. That limited communication to hand signals obviously decreasing flight commanders ability to control the situation in the air. Eventually Japanese radios became much better, but by that time (1943) heavy losses were already suffered and air superiority shifted to Allies.

c) Failure of Japanese industry to increase quality of production and create an effective quality control, to improve the quality of manufactured aircraft and equipment for them. Also in this department fits lack of additional production lines for spare parts, I know Kawasaki took such effort with their Ki-61 after field reports indicating multiple issues with lack of replacement for fuel injection systems, fuel lines, filters and so on. But that was rather an exception.
One of the biggest failures coming from it was low serviceability on front airfields and limited ability of ground crew to fix damaged airframes or replace the engines.

If there is any room for a discussion here, than I dont think Japanese Navy "resting on their laurels with the A6M", Mitsubishi was just quickly engaged with development of J2M and improving A6M. As early as in 1942 started the development of A7M but what really failed here was inability of Japanese industry to provide sufficiently powerful and in the meantime reliable engines. While A7M eventually was developed with very reliable MK9A engine, it was already end of the war.

Especially when they saw that the P-40 and F4F were able to survive it's attacks AND the fact that it wasn't able to withstand a significant amount of damage.

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Japanese were not concerned with performance or supposed robust airframes, still in 1943 they felt that they can fight on even stand with American aircraft. There is a translated by US Intelligence report written in early 1943 by Lt. Cdr. Mitsuo Kofukuda who was a fighter pilot and participated in many actions over Guadalcanal as a member of 204th Kokutai. The report concentrated on lessons learned in combat with Allies. Kofukuda indicated that in order to provide necessary protection for bomber formations the amount of escort fighters should be at least three times higher than escorted bombers, this was quickly adopted.
Then Lt. Cdr. Kofukuda concentrated on new fighters like P-38 and F4U which he admitted, had excellent high altitude performance and were faster than Zero. However he still indicated that : "the performance of the Type Zero fighter is generally excellent, I do not feel at the present time any particular inferiority in opposing the American air force fighters ..."
Kofukuda also provided a list of modifications that should be considered by the Navy in further upgrades of Zero fighter or new developments :
- introduction of ~13 mm machine guns (effectively happened with 13.2 mm Type 3 MG which was a copy of Browning chambered for Hotchkiss 13.2 mm round)
- some measures to prevent fire which would greatly increase the survivability of the pilots (that was satisfied by the introduction of automatic fire extinguishers adopted on G4M, J2M or A6M5)

Japanese Navy felt that their 20 mm is sufficient weapon, and with introduction of Type 99-II with higher muzzle velocity a limited effective range was no longer a problem.

I'd add to the Japanese mistakes the construction and armament of their bombers which lacked self-sealing fuel tanks and were woefully under-gunned.

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That's not entirely true. While G4M was unprotected for a long time(due to very specific design of wing fuel tanks, effectively preventing any kind of external protection to be placed on them) eventually Navy decided to place 20-30 mm rubber layer under each fuel tank, which of course increased drag and thus reduced speed and range. Navy also added mentioned CO2 fire extinguishers.

On contrary Japanese Army started providing protection much earlier and by the end of 1942 Japanese Army tested various armored plates on bombers and rubber covered fuel tanks on both bombers and fighters. By late 1943 such protection was a standard on Ki-48, Ki-21 and so on ...

As for the lack of defensive firepower, I totally agree.

for Italy and Japan, rampant conservatism that led to an overreliance on manoeuvre in the horizontal, unde-estimated the value of speed, climb dive and firepower and allowed these nations to delude themselves into thinking they didn't need to pursue the horsepower god

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That's a nonsense. Either Italians or Japanese were not "deluded", their industry was simply unable to quickly design and put into production high performing engines. That was coupled with lack of high octane gasoline allowing to reach higher boost ratings.
But such a pursue for high power engines existed, everything was just starting a bit later than in US or Great Britain, however by the end of the war Japanese were closing the gap in development of engines, at least in a field of pure power :


Those are coming from TAIC Summary compiled by US Intelligence.

Main factors for the power increase are :
- increase of the displacement from a maximum 2290 cubic inches for engines in 1940 to 2740 cubic inches for Mamoru engines or 3301 cubic inches for Ha-104 series (1943-1944 engines)
- general increase in manifold pressures averaging 20 % due to use of water and methanol injection
- improved supercharger efficiencies, increased pressure ratios permitting the use of higher boost at altitudes around 18,000 feet
- Increase in piston speed from an average of 2750 ft/min to average of 2940 ft/min
- increase of compression ratios, particularly Nakajima engines with Homare 21 reaching as high as 8:1
- cooling improvements and combustion mixtures nearer the best power ratios

Major factors slowing down the progress are :
- lack of high octane gasoline, even though constant efforts are made to produce such
- lack of specific metals for better engine components
- lack of two stage superchargers and turbochargers

I think the biggest mistake for the LW was related to the biggest mistake for Germany. invading Russia when the western and southern fronts were far from secure. the LW was an enthusiastic supporter of the Russian invasion and then was unable to provide decisive resources to any of the TOs that the LW was engaged in. Stretched too thinly, it became an overused, ineffective exhausted organisation incapable of having any effect on the outcomes of the battles it participated in.

Second in line is the failure of the germans to manage the economic and natural resources of the occupied territories, both in the sense of not using the resources they did have more intelligently, and also in the sense of deluding themselves in 1942 that the Caucasus could offer them solutions to their fuel issues.

That's a nonsense. Either Italians or Japanese were not "deluded", their industry was simply unable to quickly design and put into production high performing engines. That was coupled with lack of high octane gasoline allowing to reach higher boost ratings.
But such a pursue for high power engines existed, everything was just starting a bit later than in US or Great Britain.

ive got a book at home that deals with the development of the CR42 the MC200 and the G-50. There was some urgency at company level to increase the power of the engines but there was never the urgency felt for this by the customer. The fact that the RA wrote a spec that led to the CR42, introduced in quantity in 1940 no less, is telling of its innate conservatism. As a defensive fighter, the CR42 was a survivor, but as an effective air superiority weapon it was just not up to the task, and that arose mostly because of the specifications that led to it, much less so because of any failing in technology development. That is not to say that the Italians did not have problems, they certainly did, but this rather misses the point. Their customers never felt the urgency to extract more power from their engine technologies until it was well too late. The fact that the Italians eventually, and quickly were able to develop their own engines, and more significantly, adopt licence production of German engines once exposed to the full effects of the dive/climb/speed formula is self evident of their latent capability. So too is their development of the worlds best racing engines somewhat earlier, designed by the same people that were designing Italy's military aircraft a little later. The Italians had the know how to develop such engines, the industrial capacity to do so, but the customer (the RA) simply didn't see the need.

Similar motivation drove the Japanese, though they did not have quite the pedigree the Italians did in the 30's. The main operational types in 1941 were not the A6M or the Ki-43. numerically, the main types were the Ki27 and the A5M , at a time when the germans were flying and using the FW190. The Japanese had the ability to design engines of greater output, but in the case of the navy at least elected not to do so. They deliberately made the decision for an engine of small capacity for fuel economy reasons, but also they placed far too much belief that air battles would be fought in the traditional WWI style of dogfighting. they (and the Army) were simply not ready for the dive/climb/altitude/speed formula, as is brought out n a number of post war interviews. The tragedy for the Japanese is that they could have been.

Not an aviation-specific issue (although it certainly impacted aviation) was Japan's occupation of Pacific islands which left ever-increasing logistical chains for no tangible benefit. Few of the islands produced vital raw materials for Japan and all were vulnerable to being taken down piecemeal by locally stronger opposition. It's almost as if Japan's military leaders believed the propaganda maps showing a great and uninterrupted tide of Japanese influence extending across the Pacific. In reality, they were merely isolated strongpoints that were as vulnerable to encirclement and destruction as were castles in the age of gunpowder. I'm not suggesting the fighting for the islands wasn't tough...it was, extremely (some of the toughest during the entire war). I am suggesting that, from a strategic perspective, it was a complete waste of resources that achieved no tangible military objective other than setting up an attrition war that Japan couldn't hope to survive.

mikewint said:

...More tanks & aircraft wisely used in 1941 and they might have been able to take Moscow. Instead Allied productivity outstripped the Germans. This oversight is a reflection of Göring's and Hitler's foolishness and lack of administrative ability...

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To expand on this a little:
Hitler's insistence on taking Stalingrad as a priority instead of focusing on Moscow and the Soviet manufacturing centers first.

Conquest of the islands was consistent with Japanese pre-war naval strategy. The intention was that a strong defensive position would be established in these outer islands, and that as the US forces fought across the pacific there would be a level of attrition inflicted on the allies as they did so. Such attrition was to be visited on the US battle fleet by a combination of airpower, light forces, mines and submarines. To take and control the vast ocean areas, the Japanese reasoned that it would be necessary for the Allies to take an occupy these islands by force, hence the Japanese reaction was to garrison them strongly and try and fortify

Virtually none of these pre-war assumptions worked as the Japanese intended. Their focus was always the "decisive battle" of the battle fleets but this was never going to happen after pearl harbour. Fast carriers meant that concentrated airpower efforts could be brought to bear so that areas in detail could be defeated in detail and isolated so as to begin the reduction and occupation of those key islands back from the Japanese. their submarines didn't work as intended, they didn't get the time they thought they would to fortify, US subs decimated their shipping making re-supply and logistics impossible, the americans were far too strong and far too able to concentrate at the decisive point

The Japanese missed the opportunity to have a cannon-armed fighter as early as mid/late 1930s in service, the Ki-12 was a promissing aircraft, at least on paper. Ki-12 on Wikipedia: link.
BTW - the increase in compression ratio is an own goal in field of ww2 aircraft engines, it is a double own goal if one's fuel is low octane; the Japanese were to blame for not developing a two-stage supercharger for themselves, as well as too late introduction of turbochargers.

mikewint said:

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Without Hitler's wholly gratuitous declaration, the Roosevelt Administration would never have persuaded Congress to go to war in Europe instead of focusing on the Pacific. And without US involvement, and knowing that the British could never have launched a D-Day type invasion on their own, the Germans could have kept a far smaller presence in France and would have allowed them to concentrate overwhelmingly on defeating the USSR. .

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It wasn't really a wholly gratuitous declaration. it was somewhat, so this is not a do or die rebuttal. hitler had made speeches about how he would go to war against America if they kept giving assistance to the British in the form of lend lease and the battles in the Atlantic. There was virtually an undeclared war already going on since at least September '41.

In terms of German effort in the East, The germans had deployed 37 divs in france and the low countries in 41, before US entry and this dropped to as low as 21 divs after US entry in early 1942. the limiting factors affecting german commitment in the east were threefold, fuel, motor transport and manpower. In terms of these three imitations, US entry had no impact until well into 1944. The fuel shortage arose because of the effective blockade imposed by the RN on the germans. The germans deluded themselves into believing they could solve their problems in the Caucasus, but tis was never going to happen. With regard to MT production, the germans had elected prewar on a narrow base for MT production and had not invested in factory capacity in the same way as the UK and others had. that wasn't going to change or increase quickly, and the attrition rate if more MT was sent east was simply going to further increase above sustainability levels if they tried.

In terms of manpower, US commitment made no difference to available manpower. The war with the west and Poland to the end of 1941 had cost the germans less than 200000 permanent casualties. in the 6 months of fighting the soviets the heer had suffered 700000+ long term battle casualties, or more than 110000 per month. Return rates, as noted in halders diary lanquished at around 30000 per month. that meant, with no activity occurring I the west considered, the heer was rupturing to the tune of 80000 men per month. it only improved in 1942, because the germans pulled back and went defensive on 2/3 of the front, thus reducing their own casualties and attrition rates, but also doing the same thing for the russians. by May1942, the Russians had built up a reserve of more than 5 million men, admittedly short of artillery and MT, but immeasurably in better condition than the hard pressed Wehrmacht.

The turning point of the war was a combination of two things, the entry of the USSR, by far the most important, and, the entry of the US. Once the US was in against the Japanese, I think it inevitable that war would also follow against the germans.

I'm not a specialist on Italian aviation, base a lot of my info on Ali D'Italia series and conversation with a friend from Rome whose grandfather was an engineer in one of the companies. Italians had a small industry, limited funds and way too high ambitions for all the projects they could make.

Similar motivation drove the Japanese, though they did not have quite the pedigree the Italians did in the 30's. The main operational types in 1941 were not the A6M or the Ki-43. numerically, the main types were the Ki27 and the A5M , at a time when the germans were flying and using the FW190. The Japanese had the ability to design engines of greater output, but in the case of the navy at least elected not to do so.

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That's only partially correct. While main fighter for the Japanese Army was still Type 97, two Sentais were already equipped with Type 1 fighter. Indeed Nakajima failed to produce quickly large amounts of Oscars and overall development was taking excessively long.
On contrary Navy had A6M in service since late summer of 1940 which slowly replaced A5Ms. I dont have here exact tables with data, but by the outbreak of the war Zeros replaced A5M4s in vast majority of frontline units. Except for 1st, 2nd and 5th Carrier Divisions (Akagi, Kaga, Hiryu, Soryu, Zuikaku and Shokaku) Zeros were also a main fighter in 11th Air Fleet with a task to destroy any opposition over Philippines and few units based in Japan.

It is also quite weird the comparison you made, no FW-190 had to satisfy requirements expected from A6M and vice-versa. Not to mention that there werent many 190s in that 1941 ...

Japanese had the ability to design them but development times were a lot longer, not because of negligence but due to limited manpower and mentioned lack of higher octane gasoline.
Also, what you say is not true, there were available more powerful engines up to 1500-1600 HP (Kasei and later Kinsei series).

They deliberately made the decision for an engine of small capacity for fuel economy reasons,

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Like the Kasei engines ... except not.

but also they placed far too much belief that air battles would be fought in the traditional WWI style of dogfighting.

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What belief ? What WW I ?
Why would Japanese base on something they never participated in on a scale major powers did. Japanese based on their own conflicts, mainly in China and Khalkin Gol. Those experiences were basics for creating requirements for further aircraft developments.
Good maneuverability was one of the requirements but not the only one. Others were speed, range, climb and so on.
In this case Navy development was quite satisfying with every following fighter being almost 100 km/h faster than predecessor :
-> A4N - top speed 190 knots
-> A5M - top speed 237 knots
-> A6M - top speed 290 knots (with overboost 300 knots)

they (and the Army) were simply not ready for the dive/climb/altitude/speed formula, as is brought out n a number of post war interviews. The tragedy for the Japanese is that they could have been.

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Except that their fighters did have a good rate of climb, superior to anything they have encountered (with the exception of CW-21), they were relatively fast (top speed is not the only element, the acceleration is very important part as well) and had better altitude performance than adversaries.

How you imagine that "they could have been" when neither their industry could provide such a technological "jump" nor they had experiences that would lead them to such conclusions ?

BTW - the increase in compression ratio is an own goal in field of ww2 aircraft engines, it is a double own goal if one's fuel is low octane; the Japanese were to blame for not developing a two-stage supercharger for themselves, as well as too late introduction of turbochargers.

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Japanese had initially a superior altitude characteristics, A6M2 performed much better than P-39D or P-40E above 20,000 feet. It was only the actual introduction of P-38 and F4U that changed this, and since then effort was put on increasing altitude performance.

Not to mention turbochargers which were not needed until B-29, which started operating in summer 1944. By the end of the war there were multiple prototypes ready for mass production equipped with turbochargers, given that the actual need for turbochargers existed since a year or so ? That was moderately fast development.

Again, its easy to say that they needed X and Y when one sits comfortably in front of PC, takes a sip of earl grey and thinks what someone should have done. But thats not how things develop in reality. How would Japanese foresee the need for a turbocharger when there was no threat until 1944 ?

A lot of altitude "performance" is related to power to weight ratio. Early Japanese fighters had relatively good altitude performance on low power due to low weight. The A6M2 weighing around 70% of what a P-40E did. The lower wing loading helped.
The P-40 (no letter) had a lot better altitude performance than the P-40E despite the P-40E having a more powerful engine.
The P-40E weighing about 22% more than a P-40 no letter. An extra 10% or so in power didn't compensate.
The problem as the war went on was trying to balance protection and increase firepower and demand for more range (more fuel) with performance.
The 109, being fairly small and light did fairly well without special superchargers, however due to it's size it was difficult to upgun.
The FW 190A-3 certainly had guns but even though it had about 90 more hp than a 109G-6 at 18,700ft the fact that it weighed almost 25% more (and it's wing wasn't that much bigger, around 12%) meant that in comparison it lacked altitude performance.

If you want heavy armament (and long range) at 25,000ft and up you need special superchargers. However the weight and volume of special superchargers (and intercoolers and large propellers) meant that such powerplants usually could not be accommodated in existing air-frames.

Any Japanese high ranking officer/official who thought the Japanese wouldn't face high flying aircraft at some point was living in a cave in the forest. They had captured 3 flyable B-17s in the Philippines, 2 of which were E models. Granted these had nowhere near the capability of B-29s but expecting the Americans to make zero progress or not introduce new aircraft in the next 2-3 years would be a major mistake.

With turbos it was a long, long way from prototypes to service aircraft. The US had started "fooling around" with turbo chargers in the late 20s and by late 1939 had built around 100 aircraft with turbo-chargers (including over 50 P-30 fighters) and were still 2-3 years from really having combat suitable turbo-installations.

Shortround6 said:

A lot of altitude "performance" is related to power to weight ratio. Early Japanese fighters had relatively good altitude performance on low power due to low weight. The A6M2 weighing around 70% of what a P-40E did. The lower wing loading helped.
The P-40 (no letter) had a lot better altitude performance than the P-40E despite the P-40E having a more powerful engine.
The P-40E weighing about 22% more than a P-40 no letter. An extra 10% or so in power didn't compensate.
The problem as the war went on was trying to balance protection and increase firepower and demand for more range (more fuel) with performance.
The 109, being fairly small and light did fairly well without special superchargers, however due to it's size it was difficult to upgun.
The FW 190A-3 certainly had guns but even though it had about 90 more hp than a 109G-6 at 18,700ft the fact that it weighed almost 25% more (and it's wing wasn't that much bigger, around 12%) meant that in comparison it lacked altitude performance.

If you want heavy armament (and long range) at 25,000ft and up you need special superchargers. However the weight and volume of special superchargers (and intercoolers and large propellers) meant that such powerplants usually could not be accommodated in existing air-frames.

Any Japanese high ranking officer/official who thought the Japanese wouldn't face high flying aircraft at some point was living in a cave in the forest. They had captured 3 flyable B-17s in the Philippines, 2 of which were E models. Granted these had nowhere near the capability of B-29s but expecting the Americans to make zero progress or not introduce new aircraft in the next 2-3 years would be a major mistake.

With turbos it was a long, long way from prototypes to service aircraft. The US had started "fooling around" with turbo chargers in the late 20s and by late 1939 had built around 100 aircraft with turbo-chargers (including over 50 P-30 fighters) and were still 2-3 years from really having combat suitable turbo-installations.

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But if you add larger engines for more power, the plane is obviously going to be heavier, and the fastest prop fighters of WW2 and just beyond had large/powerful engines. Obviously the air forces/navies of WW2 thought benefits of larger engines more than compensates for the added weight.

Shortround6 said:

The Germans simple could not produce enough 4 engine bombers to have any real impact on the war

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Indeed. People tend to look simplistically at numbers of aircraft produced, not the weight of air frames (the British usually refer to this as 'structure weight') which is a much better reference for overall production.
Of course you can just count the numbers for aero engines. You don't have to be Einstein to work out that each of these heavy bombers needs four times the engines of a single engine fighter to fly, and that makes no allowance for reserve engines.

In the 1st quarter of 1940 the British produced a structure weight of 8.9 million pounds. In the 4th quarter of 1941 this had risen to 24.1 million pounds. I don't have the German figures, but I doubt that they are comparable for 1941.
Figures for British engine production for the same quarters are 3,940 engines (2,555 thousand horse power) and 11,236 (10,279 thousand horse power). The British produced 36,551 aero engines in 1941. The Germans built 14,400 Jumo 211s and 7,431 Daimler Benz engines (all types) in the same period. I don't have such early figures for BMW but I don't see how they and the rest could have made up the shortfall of nearly 15,000 engines compared to the British.

Cheers

Steve

Shortround6 said:

Any Japanese high ranking officer/official who thought the Japanese wouldn't face high flying aircraft at some point was living in a cave in the forest. They had captured 3 flyable B-17s in the Philippines, 2 of which were E models. Granted these had nowhere near the capability of B-29s but expecting the Americans to make zero progress or not introduce new aircraft in the next 2-3 years would be a major mistake.

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Making a progress based on few captured heavy bombers is a one thing, but facing a massive formations of bombers flying over 23,000 feet is completely different scenario to imagine. In case of progress there was considerable effort given by Japanese manufacturers to raise the critical altitudes of the engines, Ki-43-I was powered by Ha-25 with single stage, single speed supercharger having critical altitude below 12,000 feet. A6M2 was powered by Sakae 12 with same single stage, single speed supercharger and critical altitude at 13,800 feet.
By 1944/1945 standard engines in fighters were Ha-115-II with single stage, two speed supercharger and critical altitude 20,500 feet, Kinsei Ha-112-II and Homare 21 with single stage, two speed supercharger with critical altitude above 20,000 feet.

There was an issue, and exactly because of existence of aircraft like B-17 the development of better superchargers was continued. It was just too slow.

Steve, this link gives BMW engine production, WW2 German Engine Prouction

Maybe you will have better luck searching than me, but I posted links to data on this board for German aircraft production.

Milosh said:

Steve, this link gives BMW engine production, WW2 German Engine Prouction

Maybe you will have better luck searching than me, but I posted links to data on this board for German aircraft production.

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Thanks for that. It was BMW I couldn't find. Since the company made less than 3,000 engines the Germans were about 12,000 engines short of British production in 1941.
That difference (about 35% less production than the British) is not as bad as comparable figures in other areas of the aircraft industry, but it's still bad for Germany's prospects in a prolonged war.
Cheers
Steve

The two speed supercharger was introduced in 1936 by the Armstrong Siddeley Tiger VIII, the supercharger drive was innovative but the engine itself was a disaster. Wright was putting 2 speed superchargers on the Cyclone 9 in 1938 (and was reportedly offering retro fit kits), The Merlin X two speed engine was on Display at the 1938 Paris air show.
None of this was a secret. The turbo chargers on the B-17 were not exactly a secret either.

There had been 33 B-17s in the Philippines on Dec. More were flown out and joined the fighting from Java and Australia before the fall of the Philippines. That the Japanese had captured (or repaired) 3 of these aircraft is rather remarkable but the 3 aircraft in no way represented America's production capacity.

Japan had been working on two speed superchargers in 1940 and 41 and both the Ki 43 II and the A6M3 wound up with them, First prototype A6M3 flying July 15th 1941 and first Ki 43 II flying in Feb of 1942.

These engines were just part of the general trend to higher altitude going on at the time. Reports from Europe in 1939-40-41 just reinforcing it. Development of new engines was slow for the Japanese but they certainly didn't wait for the B-29 to show up before starting projects ( although it may have changed priorities).

Hiromachi said:

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Japanese had initially a superior altitude characteristics, A6M2 performed much better than P-39D or P-40E above 20,000 feet. It was only the actual introduction of P-38 and F4U that changed this, and since then effort was put on increasing altitude performance.

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The A6M3 performed much better than P-39D or P40E at altitude. However, both P-40B and P-39C were at least as good, and were better than contemporary A6M2. The good (not great) altitude capabilities of Zero, prior 1943, were very much a function of no protection, light guns' weight and light ammo load, and less due to having some great engine. Once it acquired protection (but not for fuel tanks), better armament and heavier ammo load, both speed and RoC plumeted. The Kinsei, in the A6M8 prototypes, restored the loss and added some performance, but it was too little, too late.

Not to mention turbochargers which were not needed until B-29, which started operating in summer 1944. By the end of the war there were multiple prototypes ready for mass production equipped with turbochargers, given that the actual need for turbochargers existed since a year or so ? That was moderately fast development.

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Engines with better superchargers (be it 2-stage or turbocharger) were needed to fight Western airforces if anyone wanted a favorable loss ratio. 1:1 ratio means Japan is done for. The better superharger means that engine can do, say, 1500 HP at 20000 ft, instead of 1200 HP when outfitted with 1-stage S/C.

Again, its easy to say that they needed X and Y when one sits comfortably in front of PC, takes a sip of earl grey and thinks what someone should have done. But thats not how things develop in reality. How would Japanese foresee the need for a turbocharger when there was no threat until 1944 ?

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Japanese did not need a clairwoyant to tell them that several types of LMGs, then HMGs, then 20 mm cannons, than 30 mm stuff is a waste of resources. They know (or should know) that 900-1200 HP engines won't cut it against enemies that will deploy aircraft with 1500-2000 HP on board. They know that both Bristol and Junkers were making history in 1930s with record aorcraft that are powered with multi stage superchargers, ditto for US experiments with turbos.
Expecting that enemy will do what you want is false foundation, and it happened in the expected 'decisive battle', along with massive miscalculation of US will and capacity to fight. The prepartions befor Battle of Midway are telling, for anyone that read 'Shattered sword'.
And yes, the IJN, and/or it's suppliers, failed in procurement of next fighter to replace the Zero, while they squandered many resources and time fiddling with floatplane fighters, plus with separate land-based fighter.

In hindsight (and perhaps a bit of foresight) the Zero should have gotten the Kinsei much sooner. Mitisubishi had wanted to fit it after the first prototypes had failed to make the desired speed with Zuisei engines. The Japanese navy insisted on the Sakae engine, in part due to the extra range they expected. Granted the early Kinsei didn't have the power of the one fitted to the A6M8 but in 1942/43 it had about 100hp more at most altitudes (about 10%) than the Sakae. It's larger diameter would have meant deleting the cowl guns. It might not have given extra performance to the Zero but might have allowed the increases in protection and firepower without the decrease in performace that happened. The power boosting schemes for the Sakae not really paying off.
The Japanese fell into the same trap the Germans did at times, in not spending enough effort in incremental changes in existing aircraft and trying to get a quantum jump in performance/capability with totally new designs. And as Tomo has pointed out, too many specialized designs.
As to engines there seems to have been a bit of the fighter engine vs bomber engine thing going on. They had 1400-1500hp engines, they were just using them in bombers while fitting the 1100-1200hp engines in the fighters and designing new small diameter 18 cylinder engines for the next generation of fighters.