Japanese aircraft were behind in timing to Allied aircraft.

[RCAFson]

Hey tomo pauk and RCAFson,

Thank you. Can either of you provide me with the appropriate DTIC document link? This appears to be one I have not run across before.

You can get it here:

World War II Operational Documents

Published in the Division of Naval Intelligence by the combined personnel of United States and British services for use of allied forces. Contains an alphabetical index of aircraft, contents of aircraft performance, aircraft code names, suicide glide bombs, engine section, armament section...

cgsc.contentdm.oclc.org

 

[PAT303]

The single biggest difference is western aircraft had growth potential and the Japanese aircraft didn't. The Spitfire, Mustang, FW190, P47 were all fitted with bigger more powerful engines that kept them at the front of the pack by allowing higher performance, heavier armament, more protection and the ability to carry ordinance, the downside with speed and power comes in the form of handling issues' but they were able to be solved as they presented themselves, the Japanese aircraft on the other hand couldn't be. What made the A6M and the like able to turn so well at low speed and have such tremendous range was also their biggest drawback which combined with the lack of foresight in the form of fuel improvements and continued engine development and adapting to the changes and advances on the Allied side as the war evolved ultimately left them trailing behind. Looking over the performance of Japanese aircraft on paper they did show potential but there was nothing they eventually had that the Allies didn't have 12 months earlier, and in numbers.

 

[Shortround6]

There is more than one path to follow.
The Soviets followed different paths, They took the 36 liter Hispano (bigger than the DB 601 and almost the same size as a Griffon) and beefed it up, put a 2 speed supercharger on it used it with the 96 octane fuel. The Hispano was a very light engine and that limited it's power.

The Japanese seemed to be trapped by old style thinking, like there were two types of engines, big heavy bomber engines and smaller, lighter fighter engines. It took too long to start figuring out how to put the big bomber engines in a fighter.

The Soviets also sometimes went for brute force. The Shvetsov M-82 (41.2 liters) first ran in 1940.
For some reason the Japanese failed to really develop the Nakajima Ha-41/Ha 109 of 37.5 liters. Or any of the other larger 14 cylinder radials. They stayed wedded to the small diameter engines which offered better streamlining. What was actually promised I don't know put what was promised failed to be delivered.

At any rate none of the Japanese engines got two speed superchargers into service until about mid 1942 and many of the engines didn't go into wide spread service until the end of 1942. beginning of 1943. By with time for the US only the Allison was in service with combat planes (float planes excepted) with a single speed supercharger or rather in production aircraft.

 

[ThomasP]

Thanks, RCAFson

 

[mack8]

There is more than one path to follow.
The Soviets followed different paths, They took the 36 liter Hispano (bigger than the DB 601 and almost the same size as a Griffon) and beefed it up, put a 2 speed supercharger on it used it with the 96 octane fuel. The Hispano was a very light engine and that limited it's power.

The Japanese seemed to be trapped by old style thinking, like there were two types of engines, big heavy bomber engines and smaller, lighter fighter engines. It took too long to start figuring out how to put the big bomber engines in a fighter.

The Soviets also sometimes went for brute force. The Shvetsov M-82 (41.2 liters) first ran in 1940.
For some reason the Japanese failed to really develop the Nakajima Ha-41/Ha 109 of 37.5 liters. Or any of the other larger 14 cylinder radials. They stayed wedded to the small diameter engines which offered better streamlining. What was actually promised I don't know put what was promised failed to be delivered.

At any rate none of the Japanese engines got two speed superchargers into service until about mid 1942 and many of the engines didn't go into wide spread service until the end of 1942. beginning of 1943. By with time for the US only the Allison was in service with combat planes (float planes excepted) with a single speed supercharger or rather in production aircraft.

Re the japanese engines, actually 2 speed engines were definitely in service in 1941, the Kasei/Ha-101 (G4M1, Ki-21-II) and i think the Ha-102 too (Ki-46-II, Ki-45 Kai) with production already starting in 1940 iirc (need to have another look at the USSBS reports)

 

[Shortround6]

Thank you, Francillon isn't clear on a few entries, leaving out one altitude a few times.

 

[tomo pauk]

The soviets never made anything over 96 octane in quantity during WW II. They sometimes needed help with additives.
The Soviets just used larger engines of similar weights to some of the western engines.
The Mig 3 used that large, heavy AM-35A engine BUT it made 1150hp at 7000 meters according to one source and did it on 96 octane fuel instead of the 100/130 that the Merlin 46 needed to get into the same area.
your other choice is to make a two stage supercharger (with intercooler) and run try to run combination of under 100 octane fuel.

Re. Soviet 96 oct fuel - 96 was lean rating, how good was rich rating? We know that German C3 was 96-100 oct lean, 120-140 PN rich; British 100 oct fuel from BoB was 100 oct lean and ~120 PN rich?

The Japanese seemed to be trapped by old style thinking, like there were two types of engines, big heavy bomber engines and smaller, lighter fighter engines. It took too long to start figuring out how to put the big bomber engines in a fighter.

Army was reasonably fast to have a big radial on a fighter, the Ki-44 1st flew in August of 1940.
Yes, Navy (Mitsubish) flunked with installing the Kasei on a fighter.

 

[tomo pauk]

Re the japanese engines, actually 2 speed engines were definitely in service in 1941, the Kasei/Ha-101 (G4M1, Ki-21-II) and i think the Ha-102 too (Ki-46-II, Ki-45 Kai) with production already starting in 1940 iirc (need to have another look at the USSBS reports)

The latest G3M bombers, Nakajima production starting in mid-1941, were powered by 2-speed supercharged Kinsei 50 series.

 

[mack8]

Well, japanese publications seem to suggest the G3M3 entered production in middle of 1942, so it's a bit confusing. If there is clearer info on the subject by all means would be good to see.

 

[mack8]

Re. Soviet 96 oct fuel - 96 was lean rating, how good was rich rating? We know that German C3 was 96-100 oct lean, 120-140 PN rich; British 100 oct fuel from BoB was 100 oct lean and ~120 PN rich?



Army was reasonably fast to have a big radial on a fighter, the Ki-44 1st flew in August of 1940.
Yes, Navy (Mitsubish) flunked with installing the Kasei on a fighter.

Biggest flunk was Mitsubishi messing around with that extended shaft which caused all kinds of problems, otherwise a normal Kasei installation in the Raiden could possibly allow it to get at the front in 1943.
Same with the Kyofu, first they messed around with contraprops, then with the extended shaft, then i believe finally a normal installation for the Kasei-15?

 

[mack8]

Couple of words re the Ki-43 and 44, their very late introduction is IJAAFs fault, the Ki-43 flew in early 1939 BEFORE the Zero, but from what i read among other things IJAAF didn't liked it not being maneuverable enough, so it was redesigned in late 1939 and lightened (which compromised the wing), but IJAAF still didn't liked it until the butterfly flaps were introduced, so finally it was put in production in spring 1941, with deliveries to units from summer. This is ONE YEAR later than the Zero.

If the IJAAF wasn't vaccillating like that, i don't see why the initially redesigned Ki-43 wouldn't have been in production from 1940 and delivered to units say fall 1940. Earlier delivery perhaps means they deal with the wing weakness issues earlier, so by the time the war comes they won't have those repeated wing failures in mid-fight. Also, many more Sentais could be re-equipped with Ki-43s, hence providing tougher opposition to the RAF/USAAF etc. than the obsolete Ki-27.

As it was the Ki-27 production continued until late 1942! Imagine how badly the IJNAF would have fared if they were as shortsighted with the Zero.

Same sort of story with the Ki-44, instead of going full production when it was ready about fall/late 1941, they only built 50 of them until fall 1942, until the Ki-44-II came along. Even couple of hundred Ki-44s built in this period means couple of Ki-44 Sentais (as opposed to just a meagre experimental chutai) available for the early war operations. As i understand the Ki-44 was more than a match for a P-40 or Hurricane, nevermind F2As, H75s etc.

PS: And same vaccilation and repeated redesign plagued the Ki-45, it took almost 3 and half years from prototype to service, whereas even the Ki-43 took merely 2 and half. Again a case of best being the enemy of good enough, the "good enough" initial redesign Ki-45 with Ha-25 engines could have been in production in 1940 even as an interim until the definitive Ki-45 KAI was ready.

 

[Barrett]

The maneuver vs speed argument has gone in a number of directions including this one.

My thought is that the 1942 A6M2 and Ki-43 had basically 1940 performance and armament. It did not get a lot better as the war went on. Perhaps they closed the gap to one year?
Criteria are in squadron service aircraft, not prototypes or service test.
The early fighters had great range, they sacrificed things to get it (firepower and protection).
Many other Japanese fighters did not have a range outside the range that is "normal" for the fuel capacity/speed for other fighters.
The Japanese were always behind in armament, and let's not go by barrel count but actual fire power.

The Japanese did face several handicaps. One was fuel quality, but you can't just pour in Allied fuel and get allied power levels. You often need better materials (another short coming ) and better cooling, which also may require changes in tooling and/or basic structure.
Another handicap, faced by many of the smaller nations, was the size of the engineering force. Not "Idea men" but the engineering grunts that did the stress calculations and other calculations and the draftsmen to do the drawings. Some fighters had tens of thousands of parts and each part needed at least one drawing and sometimes several. A larger company or company in a larger country can complete a project in less time due to the greater resources that can be used to bring the project to completion. Has nothing to do with talent or skill of the designer (or design team).

For Japanese army fighters
The Ki-43 II entered service in Dec 1942/Jan 1943
The Ki-44 entered "service" in late 1941 but they only built 50 of them until the service Ki-44 II showed up in Dec 1942?
Ki-61 entered service in Dec 1942/Jan 1943?
Ki-84 showed up in actual service (not trial unit) in the summer of 1944.

Just noticed Shortround's tagline of ballistic wisdom. Much like "Aim small, miss small!"

 

[tomo pauk]

Well, japanese publications seem to suggest the G3M3 entered production in middle of 1942, so it's a bit confusing. If there is clearer info on the subject by all means would be good to see.

I was going with the USSBS report about the Nakajima company.

Biggest flunk was Mitsubishi messing around with that extended shaft which caused all kinds of problems, otherwise a normal Kasei installation in the Raiden could possibly allow it to get at the front in 1943.
Same with the Kyofu, first they messed around with contraprops, then with the extended shaft, then i believe finally a normal installation for the Kasei-15?

IMO, Kyofu itself was a waste of resources, especially of the unobtainable resource - time.

 

[tomo pauk]

Same sort of story with the Ki-44, instead of going full production when it was ready about fall/late 1941, they only built 50 of them until fall 1942, until the Ki-44-II came along. Even couple of hundred Ki-44s built in this period means couple of Ki-44 Sentais (as opposed to just a meagre experimental chutai) available for the early war operations. As i understand the Ki-44 was more than a match for a P-40 or Hurricane, nevermind F2As, H75s etc.

Ki 44 was probably the closest equivalent to the Bf 109 the Japanese ever produced

PS: And same vaccilation and repeated redesign plagued the Ki-45, it took almost 3 and half years from prototype to service, whereas even the Ki-43 took merely 2 and half. Again a case of best being the enemy of good enough, the "good enough" initial redesign Ki-45 with Ha-25 engines could have been in production in 1940 even as an interim until the definitive Ki-45 KAI was ready.

What kind of performance can one expect from the Ki-45 that is powered by Ha 25 of 1940 vintage?

 

[Icorps1970]

You did, basically altitude and cooling.

The Merlin III made 1310hp using 12lbs of boost at 9,000ft, the 1030hp was at 16,250ft.
Liquid cooled engines usually had more head room for power increases. The air cooled engines were operating closer to the detonation limits.

I would note that for major US radials, NO engine was OK'ed for WEP without water injection. Also NO engine was rated at increased power levels (subject to supercharger limitations) without a major changes in engine structure, except the R-2800 when it went from 1850hp to 2000hp. The 2100hp engine in the P-47M was an entirely new engine.

Question(s). Was not the R2800 in the P-47 making peak power well over 2000 by mid/late 1943? Did not P&W run it on test stands at very high power outputs 3000 or so for hours continous?. Now cooling would be an issue in cowled engines, I don't know how the engine stand engines were cooled. But obviously the basic engine was capable of a lot more power output than was used even on the M and N models. Was it not true that P&W and/or Republic were sending techs to England to help the crew chiefs hotrod the turbochargers? I have read after action reports of P47 pilots in late 1944 out climbing Me109s at low altitude. Johnson said the up grades to his P-47 let him out climb the competition. This is not going to happen with 2000 or 2100 HP. Yes WEP needed water/methanol for COOLING the intake charge. Robert S Johnson reported indicated airspeeds at high altitude with his (hot rodded) P47D that were close to M speeds. And he did not have an "entirely new engine" SFAIK. Just wondering where you get the info since virtually all the Republic paperwork from WW-II was destroyed back in the 1960s or early 1970s. If I am correct. So unless there are military manuals on the various engines used and their specs I don't know where to get this data. But the M and N were using 2800 HP WEP R-2800 and the Increase in octane by abpit late 1943 to 145/150 greatly increased the allowable manifold pressure. This greatly increased the WEP level and then we have to ask at what point did they have to Use the water injection.
So far as the "if " the Japanese had this for that is not relevant. They and the rest of the Axis lost the war when the first bomb fell on US soil Dec 7, 1941. Nothing any of them did after that could change the outcome.

 

[mack8]

Ki 44 was probably the closest equivalent to the Bf 109 the Japanese ever produced



What kind of performance can one expect from the Ki-45 that is powered by Ha 25 of 1940 vintage?

The Ki-45 of 1940 was capable of 520 kph with Ha-25 engines. The IJAAF probably turned it's nose at it because it didn't reach 540 kph as the spec demanded. The completely redesigned Ki-45 Kai (547 kph) was almost a new aircraft, new straight wings instead of eliptical, longer redesigned fuselage, new empennages, powered by the Ha-102 engines, but it only flew in 1941 and entered service in the first half of 1942, and it was a failure anyway as a day fighter, though it found use as fighter-bomber and night-fighter (and day fighter in home defence until allied fighters appeared) .

Presumably the Kawasaki line initially intended to build the Ki-45 stood idle all that time, when it could have build the interim model even in moderate numbers from 1940 onwards, all for the sake of 20 kph. It still wouldn't cope with allied fighters, but at least with the 20mm gun it could shoot down allied bombers and do ground attack etc. in the early part of the war in 1941-42. Interesting to ponder a few of these intercepting or chasing Doolittle's B-25s.

 

[Shortround6]

Question(s). Was not the R2800 in the P-47 making peak power well over 2000 by mid/late 1943? Did not P&W run it on test stands at very high power outputs 3000 or so for hours continous?. Now cooling would be an issue in cowled engines, I don't know how the engine stand engines were cooled. But obviously the basic engine was capable of a lot more power output than was used even on the M and N models. Was it not true that P&W and/or Republic were sending techs to England to help the crew chiefs hotrod the turbochargers? I have read after action reports of P47 pilots in late 1944 out climbing Me109s at low altitude. Johnson said the up grades to his P-47 let him out climb the competition. This is not going to happen with 2000 or 2100 HP. Yes WEP needed water/methanol for COOLING the intake charge. Robert S Johnson reported indicated airspeeds at high altitude with his (hot rodded) P47D that were close to M speeds. And he did not have an "entirely new engine" SFAIK. Just wondering where you get the info since virtually all the Republic paperwork from WW-II was destroyed back in the 1960s or early 1970s. If I am correct. So unless there are military manuals on the various engines used and their specs I don't know where to get this data. But the M and N were using 2800 HP WEP R-2800 and the Increase in octane by abpit late 1943 to 145/150 greatly increased the allowable manifold pressure. This greatly increased the WEP level and then we have to ask at what point did they have to Use the water injection.
So far as the "if " the Japanese had this for that is not relevant. They and the rest of the Axis lost the war when the first bomb fell on US soil Dec 7, 1941. Nothing any of them did after that could change the outcome.

There is a world of difference between what could be done on test stands and what could be done in the Field. For one thing on test stands the engines were more closely monitored had trouble could often be detected earlier (before catastrophic failure).
There are also differences sometimes between the the factory (P & W ) says is OK and what the user (Army or Navy) says is OK.
There are some tests on

P-47 Performance Tests

P-47 improvements came in three stages, two almost simultaneously. The improved propeller/s could add several hundred fpm in climb, didn't do much for speed. There was an initial water injection set up that allowed for up to 2300hp (rounded off) at 56in pressure. Also be aware that there both different turbos on early and late P-47s and different turbo regulator/controllers. They later increased the flow rate of the water and got the engine to run at 64in pressure for about 2535hp.

There was a fourth improvement when they ran them on 100/150 fuel and there was a bit of adjustment as to what pressure was OK, some documents say 66in and some say 70in.
66in was good for 2600hp. Now with the higher grade fuel they may have been able run without water at higher pressures but in one test they were able to run level flight at 65in without water and at 70in with water in level flight without problems, however there were some cooling problems when climbing so what was OK'd for service? Pilots in combat cannot being trying to adjust throttles depending on level flight or climb or depending on outside temperature/altitude.

A number of engines were modified in the field with parts kits. Sometimes more than once. I am not sure if this is the "hot rodding" you are referring to. Having crew chiefs dream up modifications on their own was probably not going to end well.

The "C" series engines used in the P-47M and N ( and in the F4U-4 and others) was rated at 2100hp dry at 2800rpm as opposed to the 2000hp at 2700rpm of the "B" series engines.
Just about nothing could be used from a B engine on the C. Heads, cylinders, pistons, connecting rods, cranks, crankcases, valves.......everything was changed. There was enough extra finning on the heads/cylinders that they needed 10% less airflow to keep the same temperatures at the same power level as the B engine.
P-W does not list WEP in their data sheets.
You have to find the Army or Navy information.

 

[Shortround6]

The Ki-45 of 1940 was capable of 520 kph with Ha-25 engines. The IJAAF probably turned it's nose at it because it didn't reach 540 kph as the spec demanded. The completely redesigned Ki-45 Kai (547 kph) was almost a new aircraft, new straight wings instead of eliptical, longer redesigned fuselage, new empennages, powered by the Ha-102 engines, but it only flew in 1941 and entered service in the first half of 1942, and it was a failure anyway as a day fighter, though it found use as fighter-bomber and night-fighter (and day fighter in home defence until allied fighters appeared) .

Presumably the Kawasaki line initially intended to build the Ki-45 stood idle all that time, when it could have build the interim model even in moderate numbers from 1940 onwards, all for the sake of 20 kph. It still wouldn't cope with allied fighters, but at least with the 20mm gun it could shoot down allied bombers and do ground attack etc. in the early part of the war in 1941-42. Interesting to ponder a few of these intercepting or chasing Doolittle's B-25s.

According to one source that I have read it was a lot more complicated than that. Could be wrong.
The KI-45 started with a pair of 9 cylinder radial engines (and fixed pitch two blade props) after a paper study (Ki-38)using the V-12 engines used in the Ki-10 biplane.
At any rate the 9 cylinder radials turned out to be total failures but not until a series of 9 planes had been started. Several of theses were too far advanced to to be modified to take the new engine so the 4th airframe was modified to take the Ha-25 engines and all the needed changes (re stressing, CG adjustments etc.) and while this was going on the design team had started a "phase II" program. The Phase I with the Ha-25 engines had gained about 650kg empty weight over the first estimates. The Heavier aircraft had hit the 520km mark but it was armed with just two 7.7mm machine guns and that full auto anti-tank rifle. The Phase II aircraft only shared a general out line with the Phase I aircraft but there was no production sitting idle. The Japanese often ordered an initial batch of trial aircraft but with a minimum of production tooling.
The production Ki-45s with Ha-102 engines gained about 1080KG over the Ha-25 version, swapped the 7.7mm guns for 12.7mm guns, changed the rear gun (clone of the German MG 15) gained 200 liters of fuel. The Ha-102 has also be described as being more reliable than the Ha-25 but doesn't give details.

The Ho-3 cannon was almost as heavy as a Hispano, was little less powerful and fired at 400rpm (2/3s as fast), was fed by a 50 round drum with a spare drum (?) available to be changed by the radio operator/rear gunner.

 

[tomo pauk]

Presumably the Kawasaki line initially intended to build the Ki-45 stood idle all that time, when it could have build the interim model even in moderate numbers from 1940 onwards, all for the sake of 20 kph. It still wouldn't cope with allied fighters, but at least with the 20mm gun it could shoot down allied bombers and do ground attack etc. in the early part of the war in 1941-42. Interesting to ponder a few of these intercepting or chasing Doolittle's B-25s.

There is still a question of needing a twin engined fighter to carry one cannon (and few LMGs) in the air combat, with doubious performance, while other people - including the IJA - were using 1-engined A/C to carry two cannons. Fuel consumption is also double of what the newest Japanese fighters are doing.

 

[Shortround6]

The Japanese were often 1-2 years behind the west in armament. It is not enough to count the barrels, here the Japanese were often behind anyway. We need to figure out the actual firepower and at times, the combat duration.

The Italian 12.7mm was the worst heavy machine gun, talking firepower, not reliability. It used the 2nd poorest round with the lowest rate of fire.
The German 13mm was tied with the Japanese 12.7mm . Germans had the weakest round but the best rate of fire of the low rank guns. Japanese used the same ammo as the Italians but with a higher rate of fire.
US .50 cal was a step above. Powerful round with good rate of fire.
Soviet 12.7 was the best, more powerful round and the best rate of fire. It was about twice as good as the Italian 12.7mm gun.

20mm guns are even more varied. The worst 20mm gun (Japanese 99-1) was about 40% as powerful as the best 20mm of WW II, the Hispano MK V.
Rates of fire varied from 8-9rounds a second to 13rps (ShVAK) and there was a large variation in shell weight, explosive content, kinetic energy and time of flight. With a number of guns crossing over.
The Japanese Army Ho-5 20mm gun is in the bottom 1/2 of the pack with it's high rate of fire (highest?) being canceled by it's very light shell weight.
These are for firepower, efficiency (firepower for weight) is something else.

Edit: the Japanese Army Ho-1/Ho-3 was the slowest firing gun, 400rpm or about 6.66rps, round up or down as you see fit. Each round is fairly powerful so to winds up close to the Type 99 in power. >edit.

It is the fighter's job to bring enough firepower to the fight to get the job done the majority of the time.
Carrying too much firepower and not being able to get into firing position is a failure (P-39 and P-40 at times)
Carrying too little and not being able to convert firing opportunities into destroyed aircraft is also a failure.

Germans had a lot of trouble with B-17s and B-24s, ability to handle B-29s with the same armament ? So we can cut the Japanese a bit of break in 1944/45 against B-29s.
And the goal is to inflict unsustainable losses, shooting down 2-4% is not going to do it.

Sorry but two 12.7mm guns and two Ho-5 cannon were not state of the art in 1944. They were not quite as good as six 50 cal guns and six .50s were not state of the art in 1944 either, even if widely used.