# Best Japanese fighter



## bob44 (Jun 15, 2013)

Beyond the Zeke, what was the better Japanese fighter?


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## davebender (Jun 15, 2013)

IMO Ki-61 was the best IJA fighter aircraft. However Japanese difficulty copying DB601 V12 engine crippled the program.


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## Ivan1GFP (Jun 15, 2013)

J2M3 or N1K2-Ja for the Navy.
Ki-100 for the Army and perhaps the Ki-84 if it was working right.

Just my opinion.
- Ivan.


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## Civettone (Jun 16, 2013)

Without any doubt ... the Ki-84! It was the fastest. Easiest to produce. Great firepower, easy to fly, great climb rate. Maybe the best in vertical manoeuvres. 


However, the Japanese believed the Ki-100 was vastly superior to the Ki-84. According to their tests, the Ki-100 could take on 4 Ki-84s.


Kris


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## Thorlifter (Jun 16, 2013)

Another vote for the Ki-84. Also the Ki-100 deserves a nod


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## fastmongrel (Jun 16, 2013)

Kawanishi N1K2 I must admit to not knowing a great deal about Japanese aircraft so I have simply gone by what looks the best aircraft to me. Its got a real pugnacious look to it.


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## CobberKane (Jun 16, 2013)

The Ki-84 Frank, N1K2 George and Ki-100 where all potentially the equal of the best allied opposition, but all suffered from reliability problems that could not be ironed out under the pressures of war. The Ki-100 was perhaps the best developed of the three, in that it's airframe came from the Ki-61 Tony, which had been in service for several years before being re-engined. The Ki-100 was never allocated a use-name by the allies, I think because they never really figured out that it existed as a distinct fighter.


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## CORSNING (Jun 16, 2013)

The BEST is a term that must first be described. The requirements must be set before a goal can be reached. None of the other A/C listed so far were better shipboard fighters than the A6M5 simply because they were not equipped to fly off a carrier. If by the BEST we mean the A/C with the best overall performance, then a comparison of there performances over a range of altitudes must be determined. At speeds under 275 mph the A6M5 could out turn the Ki-61, Ki.84, N1K, J2M and the Ki.100. At higher speeds most of them could out turn the ZEKE. There were only two U.S. A/C that reached wide spread service that I know of that could out turn the Ki.61 at all speeds. The FM-2 and the P-40N. I believe the Ki.100 was a better turner than the Ki.61. The more reliable engine probably had some to do with that. I also believe the main reason the Japanese believed the Ki.100 was superior to the Ki.84 was because of its maneuverability and engine reliability, not its overall performance capabilities. I really wonder how the Ki.100 would have fared against the N1K2-J. From what I have read it had maneuverability approaching the A6M. While the J2M was said to have given up maneuverability for speed and climb, U.S. pilots praised its handling qualities as excellent up to 325 mph. With all that being said it has come time to compare figures. The best way I know to do that is by using the TAIC reports. While not a completely accurate example of what these A/C displayed in the field all the time the reports still give us a basis for comparison of equally prepare A/C performance.

Altitude is in meters, speed is in mph and climb is in fpm.

ALTITUDE..Ki.61-II.....Ki.84-1a.....J2M3........N1K1-J......Ki-44-II......Ki-61-I
S.L..........335/3425...362/4275...359/4835...355/4400...335/4140...302/2440
.1,000......348/3500...379/4350...374/4940...369/4410...347/4200...315/2480
.2,000......362/3540...389/3890...380/4950...369/3950...361/3950...328/2510
.3,000......363/3175...389/3570...382/4270...374/3680...361/3500...338/2500
.4,000......375/3050...388/3590...403/4320...392/3700...368/3490...352/2480
.5,000......390/3030...414/3610...415/4350...408/3760...380/3300...358/2170
.6,000......402/2960...426/3350...410/3760...408/3340...380/2800...353/1780
.7,000......409/2800...426/2870...404/3160...402/2850...373/2210...346/1250
.8,000......417/2590...416/2280...394/2440...393/2260...360/1690...335/1080
.9,000......417/2280...403/1720...383/1850...387/1700...345/1180...320/680
10,000......406/1750...387/1175...368/1150...366/1210...322/640
11,000......390/1225...N.G./575....347/600.....N.G./130...260/150

Weights....7,232 lbs....7,940 lbs...7,320 lbs....7,717 lbs...6,100 lbs....6,982 lbs.
Power.......1,440 hp....2,040 hp...1,940 hp.....2,050 hp...1,500 hp.....1,100 hp.

What this shows is that A/C that were considered the fastest climbing (J2M) and fastest level speed Ki.84 were so only at certain altitudes.


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## tomo pauk (Jun 16, 2013)

Hello, Jeff,
What would be the source for the Ki-61-II making 417mph?


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## CORSNING (Jun 16, 2013)

The Japanese A/C I really wish I had information on is the Ki.44-III. It was lighter than the Ki-44-II with a 2,000 hp. engine. Tail and wing area were increased for better handling. This model was not produced because of the "more favorable" Ki-84. Once again I guessing because of the Franks handling more than overall performance ability. I could easily be wrong though.

Jeff


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## CORSNING (Jun 16, 2013)

tomo,

I am not an aviation engineer. So on a personal level I do not have the knowledge of exactly how the TAIC report based its findings. In the GENERAL DATA section it states. " Performance figures are based on fragmentary documentary evidence and resultant extrapolation of engine ratings" The engine power for the Ha-140 is given as 1,380 hp/T.O., 1,330 hp./5,550ft (military) and1,440 hp./5,700 ft (war emergency). Test weight being 7,232 lbs.

Jeff


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## GregP (Jun 16, 2013)

Thanks for the nice compilation, Corsning. Are the speeds TAS?

I tend to discount the Ki.61 due to engine issues but, when it was running well, it was a good aircraft. I would replace the Ki.61 with the Ki.100 and add the Ki.44 Type II (with the Army Type III Nakajima Ha.109 engine of 1,520 HP) to the list of good ones. It was decently fast, had a decent climb rate, and was a pretty good piece of hardware, if not quite as good as some of the others in the list.

Too bad we don't have more Japanese WWII types flying today. They are interesting and, if decently piloted, were dangerous opponents to the end of the war.


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## CORSNING (Jun 16, 2013)

Hi Greg,
Good to here from you and tomo. You Guys always have some good input. Cobber had some good input on post #7. Just in case youall didn't catch it, I added the Ki.44-II to the list in post #8. Now imagine the Ki.44 over 700 lbs. lighter with 500 more ponies: Ki.44-III.


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## bob44 (Jun 16, 2013)

> The BEST is a term that must first be described



Best meaning, which Japanese fighters could and did face Allied fighters successfully. 
Thank you for that list Jeff.


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## GregP (Jun 16, 2013)

Interestingly, the Planes of Fame Museum used to have a flyable Ki-84 but, back in the 1970's nobody wanted to see it at an airshow, so there was absolutey NO airshow need for the type and they sold it to a Japanese museum. Lots of people wish we still had it today.

I'll see if I can dig up some first-hand recollections for some people there who flew it.

Our opinion in general is that the Japanese fighters were of good quality and were of good perfromance. We have the only J2M Raiden left in thew world and, though it COULD be restored, we doubt the engine could be. Since it has a LONG prop shaft extension, there is no American radial that could be substituted, so ... probably not in the cards.

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## Lucky13 (Jun 16, 2013)

Being that I know Jack Sh*t about these, I'd with the Frank and the George, of those that were built in any numbers.
Good thing that they didn't have the same reliability on their aircraft back then, as with most of their cars today, it would have caused problems....


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## tomo pauk (Jun 16, 2013)

CORSNING said:


> tomo,
> 
> I am not an aviation engineer. So on a personal level I do not have the knowledge of exactly how the TAIC report based its findings. In the GENERAL DATA section it states. " Performance figures are based on fragmentary documentary evidence and resultant extrapolation of engine ratings" The engine power for the Ha-140 is given as 1,380 hp/T.O., 1,330 hp./5,550ft (military) and1,440 hp./5,700 ft (war emergency). Test weight being 7,232 lbs.
> 
> Jeff



Hi, Jeff,

Not an aviation engineer myself (I have a bachelor degree on the IT field though) 
The Japanese aviation books give, for the Ha-140 engine, only 1250-1280 HP at 5700m at 2650 rpm. Guess TAIC document messed the ft for meters (it also states the 140 as two-stage engine)? Again, Japanese books ('Bunrin do' book on the Ki-61, actually) give only 610 km/h on 6000m for the Ki-61-II. Noting that Ha-140 was the descendant of the DB-610Aa, those 1250HP at greater altitude seem like a limit for the design, without going to 2 stage, ADI + much better fuel?
The TAIC manual did not have but fragmentary data, both about the Ha-140 and Ki-61-II (as they noted), so maybe we could stick at 610 km/h - 30 km/h faster than 'plain' Ki-61?


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## davebender (Jun 16, 2013)

Ki-84 and Ki-100 are 1945 aircraft. Fine aircraft but we are talking about last few months of the war.

Ki-61 entered service during 1943 and potentially could have entered service at least a year earlier if Japan had invested more resources into copying the DB601 engine. At the time it entered service Ki-61 was potentially the best land based fighter aircraft in the Pacific. That's why it gets my vote for #1.


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## jim (Jun 16, 2013)

It appears that the late war japanese fighters ,could not compete with the late war allaeid fighters . Despite their powerful engines and their small and light airframes, they were 40-50 mph slower than P51D with the super duper fuel , and over 80mph slower than the P51H
Even at the rate of climb , despite their better power and wing loadings , they were not even close to the american designs eg 
Ki 84 with 1,8 kgr/hp and 172 kgr/m2 had a roc of 3790 ft/min
F8F1 with 2,07 kgr/hp and 192 kgr /m2 had a roc of 4570 ft/m ! And with water injection would reach 7000ft/min !!! Double that of ki84!
I know , americans had better propellers, wings of very very low drag and very very high lift, two stage superchargers and gyroscopic gunsights .
It appears that despite their best efforts , japanese were at least 2 years behind in fighters performance.( Or even 5 years behind if the alleid claims ,from the china front, that P40s were superior to the ki 84, are true)
Generally, my personnal experience from studying WW2 aviation books. is that alleid aircrafts needed much less power to achieve superior performance in comparison with the axis aircrafts, and less stuctural weight to achive similar or superior structural strength.

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## davebender (Jun 16, 2013)

Say what? Most WWII era U.S. fighter aircraft were very heavy compared to everyone else.

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## CORSNING (Jun 16, 2013)

You tell 'em dave. The U.S. fighters were larger and heavier overall. They had to be to get the range. 

Greg, TAS, it is not a practice to put a graph together using indicated airspeed. That would not mean much in the real world considering the location of the tube has a lot to do with how accurate the readings at the gauge are.

bob44, Could and Did is two very different things. Putting them together is not always very easy. When comparing aircraft performance I believe it is only a true comparison if you examine the aircraft as all things being equal. The Russians and the Japanese late war are perfect example of all things were not equal. They were were building sound designs. They were just building them under less than ideal situation.


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## proton45 (Jun 16, 2013)

Really? No one for the Ki-44?


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## davebender (Jun 16, 2013)

Not buying that explanation. P-47 was the most numerous U.S. fighter aircraft so it's my standard for comparison. 

P-47 combat radius was no better then A6M2 yet it weighed three times as much. In fact P-47D weighed 50% more then twin engine Fw-187.

7,939kg. P-47D loaded weight.
~5,000kg. Fw-187 loaded weight.
4,250kg. Me-309 loaded weight. 700 liters internal fuel. Drop tanks optional.
3,470kg. Ki-61 loaded weight. 550 liters internal fuel plus 2 x 200 liter drop tanks.
2,410kg. A6M2 loaded weight. One of the longest range fighter aircraft of WWII.


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## tyrodtom (Jun 16, 2013)

What are you trying to compare dave ? Two aircraft that never reached production, and the other two had about half the HP of the P-47.


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## CORSNING (Jun 16, 2013)

dave,
The A6M2 was one of the longest ranging aircraft for the first half of the war. By 1944 the U.S. fighter A/C capable of flying over 2,000 mls.: P-38, P-47, P-51 and P-63. I'm just saying they were heavier than the Bf.109, A6M and most other Japanese fighters. That gave them this ability and the strength to carry heavier payloads. tyrodtom's right, what is your point? I doubt that the Me-309 could carry 2,000 lbs. of rockets/bombs and travel 1,500 mls.

Nice proton, where's the picture of the Ki-44-III?


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## Shortround6 (Jun 16, 2013)

P-47 was one of the first single engine fighters designed to carry almost 1600lbs worth of guns and ammo, not including mounts, ammo boxes, chutes, gun heaters and the like. It was designed to fly at 400mph or more at 30,000ft. It was designed to an 8 "G" load factor (ultimate 12 "G"s). You don't get such capabilities from small, light aircraft. 

You can argue that the US should not have specified such a heavy armament but once they did the size of the airplane followed. Over 4 times the weight of guns and ammo that an early Zero carried and over 5 times the weight of a Bf 109F. (3 gun) 

The US designers were not stupid or lazy. The Customer (Army or Navy) gave them a requirement and they filled the requirement. The requirement may have been strange but unless the buyer backed off on the weight of the guns and ammo ( or strength of the aircraft) the weight of the airplane followed.


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## Civettone (Jun 17, 2013)

davebender said:


> Ki-84 and Ki-100 are 1945 aircraft. Fine aircraft but we are talking about last few months of the war.
> 
> Ki-61 entered service during 1943 and potentially could have entered service at least a year earlier if Japan had invested more resources into copying the DB601 engine. At the time it entered service Ki-61 was potentially the best land based fighter aircraft in the Pacific. That's why it gets my vote for #1.


Who says they did not invest more resources into copying it? 



proton45 said:


> Really? No one for the Ki-44?
> 
> View attachment 236228


Yeah, I think the K-44 was the best Japanese mid-war fighter. Would be interesting to see a comparison between the Ki-44-II and the Ki-61-I 

Kris


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## tomo pauk (Jun 17, 2013)

jim said:


> It appears that the late war japanese fighters ,could not compete with the late war allaeid fighters . Despite their powerful engines and their small and light airframes, they were 40-50 mph slower than P51D with the super duper fuel , and over 80mph slower than the P51H



The late war Japanese fighters (Hayate, Raiden, Shinden-kai) were 20-30 mph slower than P-51D (430-440 mph vs. 410-427 mph). Their engines were powerful (when able to be operated in full power), but the engines were radial types, and that costs in drag, despite efforts to streamline the installation. The engines were also single stage designs, and that shows at 25000 ft and above, where Merlin Mustang can use the thiner air to outperform much of other fighters.



> Even at the rate of climb , despite their better power and wing loadings , they were not even close to the american designs eg
> Ki 84 with 1,8 kgr/hp and 172 kgr/m2 had a roc of 3790 ft/min
> F8F1 with 2,07 kgr/hp and 192 kgr /m2 had a roc of 4570 ft/m ! And with water injection would reach 7000ft/min !!! Double that of ki84!



Ki-84 with water injection was good for 4275 ft/min at SL, the F8F-2 (=1948 plane) making 4300 ft/min when using water injection (2500 HP) at SL.



> I know , americans had better propellers, wings of very very low drag and very very high lift, two stage superchargers and gyroscopic gunsights .



Bearcat's wing was not that very very low drag item - 23000 series wing profile, 18% thick at root, 9% at tip. Lift was probably a major plus, though. Bearcat never received two stage engine, the E series engine in the -2 was a performer, never the less.



> It appears that despite their best efforts , japanese were at least 2 years behind in fighters performance.( Or even 5 years behind if the alleid claims ,from the china front, that P40s were superior to the ki 84, are true)



Talking about P-40 being superior than Ki-84 is silly (not sure what you're aiming at??). Japanese were rather late in introduction of 'second generation' of ww2 fighters, maybe a year behind the allies?



> Generally, my personnal experience from studying WW2 aviation books. is that alleid aircrafts needed much less power to achieve superior performance in comparison with the axis aircrafts, and less stuctural weight to achive similar or superior structural strength.



Again, not sure what you're aiming at? 
Some Allied planes were fast for installed power size/weight (P-51 vs Spitfire and Bf-109, A-20 vs. Beaufighter, Mosquito vs. pretty much anything similar), other ones were not that fast despite power (Typhoon, Hellcat, Corsair) - weight, size drag being detriments. Some were slowish despite the small size (Yak-1, war-production MiGs, P-40). Some were great under 15000 ft (Typhoon, Tempest, P-39, Allsion Mustangs, much of the Soviet fighters), other were no good under 20-25000 ft (P-47). US stuff was heavy, UK Soviet ones were lighter. US stuff was again considered rugged, usually carrying greater weight of fuel/ammo/weapons (not saying punch was greater, just the weight of weapon ammo).


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## Shortround6 (Jun 17, 2013)

tomo pauk said:


> US stuff was again considered rugged, usually carrying greater weight of fuel/ammo/weapons (not saying punch was greater, just the weight of weapon ammo).



"and less stuctural weight to achive similar or superior structural strength."

This would take some analysis. Most weight charts don't break it down enough. The American stuff was rugged and stressed for about as high or higher a "G" load than many other aircraft of similar type. There are exceptions though.

Wither this was done with LESS _structural_ weight is an interesting question. We know the weight of a number of wings for US fighters and some others but the wing weight _often includes_ armament provisions (the weight of the mounts, ammo boxes, feed and empty chutes, gun heating arangements,etc often disappears, it is not listed in the armaments section at any rate). Throw in things like flaps, yes they are part of the structure and yes they do impose loads on the air frame but they have NOTHING to do with the wing standing up to an 8 "G" load repeatedly. 

It may, or may not include landing loads and those differ from plane to plane. F4F imposes NO landing loads on the wing (or darn few) likewise the Bf 109 only imposes minimal landing loads on the wing. P-51s and P-47s impose much larger landing loads and the F6F and F4U are in a class by themselves for US single engine fighters with the carrier landings. 

Without some sort of statements from the designers or stress-men I don't think such a statement can be proved or disproved.


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## CORSNING (Jun 17, 2013)

jim, The horse power listed in the TAIC reports was for a perfectly working engine. That was something not all Japanese A/C had in late 1944-1945. The power levels listed were not exact what was actually out in the field. The Ki.84's figures are for a 2,050 hp. A/C. From the information I have read, some in the field Franks were barely cranking out 1,800 hp.

Civettone,
As soon as I finish this post I plan to jump back to my original post and add the Ki.61-I to the list.

tomo,
You might have opened a can of worms comparing the Ki.84 to the F8F-2. Different generations built for different jobs. If I get a chance in the next couple of days I'll line up the Ki.84-1a to the fully loaded "clean" F8F-1. They were built more for the same jobs.

Shortround,
Any two A/C with semi-close performance can be loaded to outclimb the other. If I get a chance I'll do some digging in my files and see what I can come up with. Right off the top of my head I think the figures for the two in absolute clean condition and equipped for interception/air superiority duty is: F8F-1:~6,300 fpm. P-51H: 5,850 fpm. at S.L. 

All,
There is no doubt in my mind (at this time) that the Bearcat was a more dynamic fighter aircraft (within its realm of limitations).

Sorry Shortround, I got my thread mixed up. I'll pop this over to "F8F Bearcat rate of climb" when I get the chance.

God bless you all, Jeff


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## Ivan1GFP (Jun 19, 2013)

Regarding the Ki-61-I as one of the best Japanese fighters, I believe it really should not count.
It was actually available in numbers which meant something but in performance, it was very comparable to a Messerschmitt 109E but about 15 mph faster probably because of a better streamlined airframe.

The Ki-61-II had 1500 HP instead of 1175 HP, so it should have been faster. I believe the TAIC was working on the assumption that the Ha-140 was equivalent tot the DB 605 in their speed estimates. In flipping through the Bunrindo books and comparing the stated power levels of the Ha-40 versus Ha-140 at various altitudes, with the simple estimate of speed rising as to the cube root of the power difference, I can only get about 390-400 mph for the Ki-61-II. (400 mph is being VERY generous in picking data.)

The Ki-100 had the same 1500 HP but was around 500 pounds lighter than the Ki-61-II which put it back at nearly the same weight as the Ki-61-I.

The Nakajima Homare engine generally didn't achieve anywhere near the power levels it was designed for so while in theory, a superbly maintained Ki-84 would be capable of 425 to 430 mph, the aeroplanes in the field generally didn't achieve that. It was bad enough that the Japanese even tested installations of a Ha-112 in the Ki-84 airframe because at 1500 hp or so, it made more power in the actual aircraft than a Homare typically would.

The N1K2-J, although it used the same engine as the Ki-84, didnt seem to have quite the same record of problems. This is from the book Genda's Blade which describes the Shiden-KAIs as being superior to the Hellcat even when running on fairly low octane "aviation" fuel.

Regarding the US opposition, the Bearcats were not bad, but had their structural issues to work out and never became operational. The real opposition was Hellcats and -1 Corsairs and various Army types. Pilot accounts from Genda's Blade show them as feeling their Shiden-KAI to be quite superior to the Hellcat but a bit inferior to the P-47 when fighting at altitude. This group is interesting because although they had the best of the remaining navy pilots and the "best" fighter available, they were still losing to the US pilots at a rate of about 3 to 1.

My vote for best Japanese fighter is still the J2M because from various reports of captured examples (including from old Air Power articles), they appeared to be quite good build quality and have decent power and performance from a reliable engine.

This is just my interpretation from having done a fair amount of reading.
- Ivan.


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## CORSNING (Jun 19, 2013)

Ivan, 
That sound like a pretty good summation to me. It's funny, a few minutes ago I was just going over the comparison of the Bf.109E vs. the Ki.61-I. Pretty much the only advantage the Messer had was its climb rate. But then again the time frame would bring up the late Bf.109F/early Bf.109G, and that's a different ball game. Through in the Ki.44-II and it evens thing up a little.


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## Civettone (Jun 19, 2013)

Seems to me the Bf 109E was faster than the Ki-61-I at all altitudes



Kris


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## CORSNING (Jun 22, 2013)

Civettone,

Sorry I took so long to pull up the info I have. I started cleaning up the garage for the last time this year (we had a lot of crap) and I just recently quit smoking (38 years on/off). So.......that's all I have to say about that. My main studies are Japanese, Russian and U.S. A/C. I am no authority on German and U.K. A/C. The following figures for the Bf.109E-3, as far as I know at this time, are from German documents. The following figures for the Ki.61-I are from the T.A.I.C. report (because that is the best information I have on this A/C at this time). They look like this:

Altitude...Bf.109E-3...Ki.61-I
Meters....Miles Per Hour......
S.L.........310...........302
.1,000.....317...........315
.2,000.....329...........328
.3,000.....335...........338
.4,000.....345...........352
.5,000.....354...........358
.6,000.....351...........353
.7,000.....348...........346
.8,000.....331...........335
.9,000.....324...........320

The figures for the 8,000 and 9,000 meters are from the Swiss test because the German info I have does not go above 7,000 meters.

Jeff


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## Civettone (Jun 22, 2013)

Thanks for the info, Jeff. BF 109 is only a bit faster at low altitudes, the Ki 61 is a bit faster higher up. But quite close all in all.

A bit remarkable as the Ki-61 was bigger and heavier. 
Kris


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## Shortround6 (Jun 24, 2013)

Not really remarkable, the 109E was a rather draggy airplane. As shown by the difference in performance with the early F or F prototypes using the same engine.


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## Cave Tonitrum (Jun 24, 2013)

A video I stumbled across regarding the Ki-84 and J2M.


_View: https://www.youtube.com/watch?v=FCfKUOj9ojI_


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## zoomar (Jun 27, 2013)

The problem with all Japanese fighters is they all had major problems, stemming either from basic design or, especially after 1944, declining workmanship. That said, the Ki-84 and the N1K2, seem to be the best, retaining typical Japanese good handling with a powerful (if unreliable) engine, good firepower and adequate protection. Had the war continued, I suspect they would be more amenable to further development, unlike the Ki44, Ki-61/100 or J2M.


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## GregP (Jun 27, 2013)

What makes you think the J2M wasn't a good candidate for development?


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## Civettone (Jun 28, 2013)

Ivan1GFP said:


> It was bad enough that the Japanese even tested installations of a Ha-112 in the Ki-84 airframe because at 1500 hp or so, it made more power in the actual aircraft than a Homare typically would.
> 
> The N1K2-J, although it used the same engine as the Ki-84, didnt seem to have quite the same record of problems. This is from the book Genda's Blade which describes the Shiden-KAIs as being superior to the Hellcat even when running on fairly low octane "aviation" fuel.
> 
> Regarding the US opposition, the Bearcats were not bad, but had their structural issues to work out and never became operational. The real opposition was Hellcats and -1 Corsairs and various Army types. Pilot accounts from Genda's Blade show them as feeling their Shiden-KAI to be quite superior to the Hellcat but a bit inferior to the P-47 when fighting at altitude. This group is interesting because although they had the best of the remaining navy pilots and the "best" fighter available, they were still losing to the US pilots at a rate of about 3 to 1.


They tested a Ki-84 with a Ha-112 for conversion into the derived Ki-116, a lightweight Ki-84. There is no reason to assume that this was because the Homare was unsatisfactory. You said yourself that the Homare was working okay for the Shiden. In fact, that is not true either. The N1K2-J also had problems with the Homare. Of course the Kı-84s and Shidens still lost against American planes, the general level of the American pilots was far superior. Even if you read Japanese accounts on this or that plane, you have to take into consideration, that pilots have a limited view on things surrounding them. They may find their plane inferior or superior to the enemy, but the actual results will not always prove them right. A lot of it has to do with mentality and moral, they tend to cloud their judgment.

Kris

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## razor1uk (Jun 28, 2013)

Ki-116, the Tsurugi? wasn't a lightweight fighter but a cheapest in cost and materials A/C to be used to carry out a suicide attack with a plan-form similar to the Ki44/84


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## Civettone (Jun 28, 2013)

No mate, you are talking about the Ki-115 Tsurugi or Tōka.


Kris


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## Ivan1GFP (Jun 29, 2013)

Civettone said:


> They tested a Ki-84 with a Ha-112 for conversion into the derived Ki-116, a lightweight Ki-84. There is no reason to assume that this was because the Homare was unsatisfactory. You said yourself that the Homare was working okay for the Shiden. In fact, that is not true either. The N1K2-J also had problems with the Homare. Of course the Kı-84s and Shidens still lost against American planes, the general level of the American pilots was far superior. Even if you read Japanese accounts on this or that plane, you have to take into consideration, that pilots have a limited view on things surrounding them. They may find their plane inferior or superior to the enemy, but the actual results will not always prove them right. A lot of it has to do with mentality and moral, they tend to cloud their judgment.
> 
> Kris



I believe I was correct in stating that the Ha-112 typically made more power in the field than the Ha-45 would. I don't remember trhe source, but the number I have seen was around 1300 HP for a Ha-45 which is nominally a 1900-2000 HP engine. The Homare simply could not reliably deliver the performance it was designed for.

Other than that, your disagreement with my post is strange because you are stating almost exactly what I was stating.

I never stated that the Shiden-KAI didn't have engine issues. I just said that it didn't have the same record of problems that the Hayate did. I have no evidence for this next statement but here goes anyway: I believe that a lot of the difference in mechanical reliability was because of where the units operating this aircraft were located in the supply chain. The 343 Kokutai was based on the home islands as opposed to China, Burma, New Guinea, etc.

The book Genda's Blade seems to show that 343 pilots thought they were generally doing pretty well. They thought they were shooting down a lot more US aircraft than they were. The US pilots thought the 343 was doing well also because their tactics and coordination was good. The 1 to 3 kill to loss ratio is MY OWN count from tallying up each side's losses for the recorded encounters. Both sides over-claimed as usual. What was rather pitiful was the deaths of some of the best Japanese pilots due to mechanical failure or circumstance (Kanno, Muto, Sugita).

Regards.
- Ivan.


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## CORSNING (Jun 29, 2013)

And there you go. Nice summation again Ivan. The example of "where" a certain A/C was stationed, "what" A/C it fought, "who"(quality of pilots) was flying the A/C and "how" it was implemented had everything to do with how well it did in combat (its win/loss record). What I'm trying to say is, just because A/C No.1 had a better win/loss record than A/C No.2 does not always meanA/C No.1 was the superior fighter aircraft/fighting machine.

Jeff


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## GregP (Jun 30, 2013)

Talked with Steve Hinton and Ed Maloney today about the Ki-84 we used to have. He said our example was barely flyable and had a very slightly bent prop and they could not get rid of the vibration ... and the gear up locks were nonfunctional. So, although it was quite pleasant to fly, they never got into the higher-performance part of its envelope. At the time, there was simply no demand for it on the airshow circuit and they had NO spare parts so, when the offer came in from Japan, they jumped at it.

The only people who flew it were Don Lycans and Bud Mahurin.


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## cherry blossom (Jun 30, 2013)

I am coming to the view that the post-war American trial performance of the Ki-84 giving a maximum speed of 427 mph is misleading. My reasoning starts from the engine data given at q‹ó‹@ƒGƒ“ƒWƒ“ˆê——E“ú–{ŒR, which gives powers:

Ha-45 11 – Take off 1800/2900 – Military 1650/2000/2900 and 1460/5700/2900 
Ha-45 22 – Take off 2000/3000 – Military 1890/1800/3000 and 1750/6450/3000

It also gives for the Mitsubishi's M9K

Ha 43-11 – Take off 2200/2900 – Military 2070/1000/2800 and 1930/5000/2800

Now the Navy's A7M1 Reppu was powered by a Nakajima Homare 22 and is quoted as only having a maximum speed of 310 Knots at 6,190 m (357 mph). The A7M2 was powered by the M9K and had a speed of 339 kt at 6,600 m (390 mph). If we take those speeds and cube them, we can guess the ratio of the horsepower as around 1.303 assuming the weight, drag and propeller efficiency is the same. In fact the M9K was heavier (980 kg vs. 830 kg.) and wider (1230 mm vs. 1180 mm) than the Homare and propellers get less efficient at higher speed. Thus the 1.3 ratio is too low. However, dividing the 1930 hp of the M9K by 1.303 gives 1480 hp. Thus we can be fairly sure that a Homare 22 as supplied to Mitsubishi in Japan gave less than 1480 hp at around 5000 m.

Now it is unlikely that Nakajima was simply telling lies about the performance of the Homare 22. A prototype engine would almost certainly give 1750 hp at 6450m at 3000 rpm. However, the production engines could not match this. Rinkol http://www.ww2aircraft.net/forum/aviation/kawanishi-n1k1-j-kasei-37359.html#post1023836 suggests “The early Homare engines suffered from production quality control problems affecting the intake passages” and that is the best explanation that I have found. Thus the only Homare 22 engines that Nakajima could supply to Mitsubishi had much worse performance than Nakajima prototypes.

Now if we go to the post-war American tests, everything makes sense if they managed to get the quoted performance out of the Ha-45. It is possible that the test aircraft actually had a hand made prototype engine from Nakajima. Alternatively, it is possible that the highly skilled American technicians had a translated manual quoting the expected power, realised that their engine was underperforming and set to work with their well equipped machine shop to remake any defective parts until they brought their engine up to its quoted performance. 

The point is that most Homares in either the Ki-84 or the Shidens did not give their quoted performance and that the high speeds quoted could only be achieved with specially manufactured engines.

ps. On reflection, another possibility is that Nakajima actually solved the manufacturing problem very late in the war so that some Ha-45 engines were mass produced in 1945 with the theoretical performance and that one of those went to America for the Ki-84 test.


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## Civettone (Jun 30, 2013)

My guess is that low quality control does not automatically mean less performance, only bigger chance of less performance. As such, I think some Homares delivered the expected performance, others did not. One can debate about the ratio.


Kris


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## Rogi (Jun 30, 2013)

May we factor in captured aircraft that the Japanese used? Or just home grown Japanese aircraft? 

Ki-61 if homegrown,

I will wait to see if captured is included


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## fastmongrel (Jun 30, 2013)

Civettone said:


> My guess is that low quality control does not automatically mean less performance, only bigger chance of less performance. As such, I think some Homares delivered the expected performance, others did not. One can debate about the ratio.
> 
> 
> Kris



Quality control gives you the chance of repeating a good engine again and again. Poor quality control can sometimes produce a cracker of a an engine but with no quality control you will never know how you did it, thus no chance of repeating. I used to work for my Aunt and Uncle who owned a British Leyland dealership my cousin and I used to pre delivery inspections and some of the engines were great they started first turn and ticked over smoothly, others from the same batch virtually needed a crankcase up rebuild. British Leyland QC was non existent so they didnt realise that the engine casting moulds were worn and tolerances had gone, plus things like crankcase bearing boring machines were old and worn so some cranks would spin with a finger others would only turn with the assistance of a scaffolding pole. Some people wonder why BL dissapeared others wonder how it lasted so long.

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## GregP (Jun 30, 2013)

Poor surface quality in an intake passage will rob some power, but not much. Poor quality exahust passages will not affect power much if any. It certainly would in a normally aspirated engine, but all these engines were supercharged. Boosted engines are completely different from normally asiprated engines as far as flow goes. Of much more concern would be the main bearing clearances. 

Tight clearances will overheat at higher rpm and cause premature failure and loose clearances will not allow the engine to develop full oil pressure and will limit manifold pressure unless you want engine failure. So the pilot would be able to pull only so much power before the oil pressure gets to the limit. Any more power would be a personal gamble.

One place where quality would really affect performance would be if the props were of poor quality finish.

Naturally, the airframe fit and finish is high on the list, too. Leaky gaps are very draggy. You want to prevent air from entering anywhere it is not supposed to enter.


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## CORSNING (Jun 30, 2013)

I really miss the Triumph Spitfire. In my youth I was 6' 4 1/2" and a Spitfire fit like a tailor made glove. It would not win any drag races but who cared. It was pure fun. Now that was definitely one of the best cars to come out of the UK in the 60's/70's.

And I don't care who you are, Jeff.


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## fastmongrel (Jun 30, 2013)

CORSNING said:


> I really miss the Triumph Spitfire. In my youth I was 6' 4 1/2" and a Spitfire fit like a tailor made glove. It would not win any drag races but who cared. It was pure fun. Now that was definitely one of the best cars to come out of the UK in the 60's/70's.
> 
> And I don't care who you are, Jeff.



I like the Triumph Spitfires as well. I briefly had a MkI GT6 which looked beautiful, sounded beautiful but if you had to lift in a fast corner the Swing Axle and torque reaction from the drive shaft would make you go backwards through a hedge and end up in a field. Luckily the farmer towed it out of the muddy field before before it sank up to the door cills.


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## GregP (Jun 30, 2013)

Hye Corsining,

I REALLY liked the Triumph GT-6. It was like a roller skate with a lot of power. That 6-cylinder was a real kick when you pushed it hard .... unutil you had to fix it, that is. Also loved the Austin-Healy 3000. Another kick in the panrts when stepping on the go-fast pedal.

Both are sort of like the difference between a Van's RV-4 and a Harmon Rocket. The RV-4 is sweet but the Harmon Rocket is just unbelievable and accelerates when climbing at a 45° angle.

Maybe back to Japanese fighters, like the Toyota 2000GT featured in an early James Bond film, _You Only Live Twice_. Anyway, back to subject ...

I think the top 3 - 4 were too close to call and "the best", like their European and American cousins, probably depended on the mission and the pilot more than the plane.

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## cherry blossom (Jul 1, 2013)

I am not sure that Nakajima Homare engines were like British Leyland cars. My mother bought a Triumph Acclaim in 1982 and parked it soon after buying it only to discover that the gearbox had fallen out onto the ground under the car once it was no longer held in place by the transmission. However, not all British Leyland cars had such problems and my mother was not testing her Acclaim before buying several thousand. Had she been an important customer, someone may have checked the bolts which should have held the gearbox in place. 

By contrast, Nakajima apparently couldn't find a good Homare 22 for the Reppu in 1944 when a major contract might have depended on finding one. We could imagine that they said “any old rubbish is good enough for Mitsubishi” but they must have known that Mitsubishi would use poor performance to argue for the use of the M9K (Ha 43). 

It is also clear that the airframe and propeller could not account for the A7M2 going much faster and climbing much quicker than the A7M1. Mitsubishi calculated that their Homare was only giving 1300 hp when the spec said it should be giving 1750 hp.


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## Milosh (Jul 1, 2013)

I to had a Triumph GT6+. It would go like stink (2l. and 2 speed overdrive). Never had a problem like you Fastmongrel in cornering. Didn't like the rain tho (water entered through the hood grills) and the carbs had to have oil added every so often. Eventually pulled the rear radius rods out of the floor they were attached to.


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## Shortround6 (Jul 1, 2013)

I had the big brother, A TR-250 (TR-5 with carbs instead of fuel injection). 


_Curse you, George Lucas._


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## fastmongrel (Jul 1, 2013)

Milosh said:


> I to had a Triumph GT6+. It would go like stink (2l. and 2 speed overdrive). Never had a problem like you Fastmongrel in cornering. Didn't like the rain tho (water entered through the hood grills) and the carbs had to have oil added every so often. Eventually pulled the rear radius rods out of the floor they were attached to.



They cured the handling problems in the Mk2 GT6 Spitfires by fitting rubber dampers on the drive shafts and fitting a revised wishbone rear suspension which turned a lump into a Lotus beater. Modern radials and modern dampers keep the GT6 Mk1s on the road but you still better know a panel beater if you have to lift off and brake at speed in a bend. If you go to a Triumph owners meet you will soon find someone who put there GT6 Mk1 or Vitesse Mk1 through a hedge 

The oil in the carb was a damper to stop the needle bouncing up and down and causing erratic running.


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## fastmongrel (Jul 1, 2013)

Shortround6 said:


> _Curse you, George Lucas._



He wasnt known as "The Prince of Darkness" for nothing


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## Milosh (Jul 1, 2013)

fastmongrel said:


> The oil in the carb was a damper to stop the needle bouncing up and down and causing erratic running.



I know what the oil was for.

Rubber dampers. You mean the rubber universal joints.


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## fastmongrel (Jul 1, 2013)

Yes the drive shaft do-nuts they are called Rotaflex or something. They act as CV joints and driveshaft dampers, basically a metallastic engine mount modified with a big hammer


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## tyrodtom (Jul 1, 2013)

GregP said:


> Poor surface quality in an intake passage will rob some power, but not much. Poor quality exahust passages will not affect power much if any. It certainly would in a normally aspirated engine, but all these engines were supercharged. Boosted engines are completely different from normally asiprated engines as far as flow goes. Of much more concern would be the main bearing clearances.
> 
> Tight clearances will overheat at higher rpm and cause premature failure and loose clearances will not allow the engine to develop full oil pressure and will limit manifold pressure unless you want engine failure. So the pilot would be able to pull only so much power before the oil pressure gets to the limit. Any more power would be a personal gamble.
> 
> ...




In my 20+ years of racing, and some experience with supercharged tow trucks, I've found what you said about the importance of intake and exhaust passages to be totally wrong, most of the improvements in horsepower come from increases in intake flow, AND exhaust flow, thru improvements to intake and exhaust passages and camshaft timing and duration. You can't get fuel/air mixture in if you can't get it out.

And a supercharger isn't as effective with bad intake and exhaust passages. All the same rules apply, supercharged or normally aspirated.
And I can't believe that drastically changes if the engine is at 10,000 or 20,000 feet in a aircraft.


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## Ivan1GFP (Jul 1, 2013)

GregP said:


> Talked with Steve Hinton and Ed Maloney today about the Ki-84 we used to have. He said our example was barely flyable and had a very slightly bent prop and they could not get rid of the vibration ... and the gear up locks were nonfunctional. So, although it was quite pleasant to fly, they never got into the higher-performance part of its envelope. At the time, there was simply no demand for it on the airshow circuit and they had NO spare parts so, when the offer came in from Japan, they jumped at it.
> 
> The only people who flew it were Don Lycans and Bud Mahurin.



I have seen photographs of this aeroplane in flight in old books.

It was a beautiful machine but had lots of obvious problems.
Your comment about the landing gear up locks is interesting because from the photographs I have seen, the gear never retracted all the way. The inner gear doors closed before the gear was up so the main gear was trapped outside. Also, the tail wheel must have had some serious issues because this plane looked like it had a new strut fabricated which could not possibly retract.

From what I have read elsewhere, this aeroplane's flying days are finished, but perhaps it can still be used as a template to make new ones. To save space in storage, apparently someone decided to saw through the wing spars.

- Ivan.


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## Ivan1GFP (Jul 1, 2013)

cherry blossom said:


> I am coming to the view that the post-war American trial performance of the Ki-84 giving a maximum speed of 427 mph is misleading. My reasoning starts from the engine data given at q‹ó‹@ƒGƒ“ƒWƒ“ˆê——E“ú–{ŒR, which gives powers:
> 
> Ha-45 11 – Take off 1800/2900 – Military 1650/2000/2900 and 1460/5700/2900
> Ha-45 22 – Take off 2000/3000 – Military 1890/1800/3000 and 1750/6450/3000
> ...



Hello Cherry Blossom,

For the most part, I believe you are correct. Not that it makes much difference but there is a difference in altitude of 400 meters which might swing the results by a couple percent.

The early models of he Ha-45 had a high pressure fuel injection system. It didn't work reliably so they eventually switched to a low pressure system. That apparently didn't work reliably either. The Hayate's Constant Speed Propeller (CSU as described in tests) was constantly failing. The spark plugs apparenly fouled badly so the US service people eventually went with a hotter US plug (I wish I could find the report of all the repairs done). IIRC, the engine itself wasn't bad, but a lot of the supporting equipment was not reliable and needed work.

Another issue to take into account is how the power ratings of the engine were achieved.
As an example, for the Ki-61-I with a Ha-40 engine:
Take Off: 1175-1180 HP @ 2500 RPM at +330 mm Hg (1.4765 ATA, 42.9 inches Hg)
Military Power: 1080 HP @ 2400 RPM at +240 mm Hg (1.346 ATA, 39.37 inches Hg) (4200 Meters altitude)

Japanese testing would have used the Military rating. US Testing would have used the War Emergency rating which in this case is probably pretty close to the Take Off rating.

420-something mph isn't unreasonable for an aircraft like this. The FW 190 is quoted at 408 mph at around 20,000 feet on only about 1500 HP or so and that was probably a bit of an understatement because US testing of a ground attack version (G Model?) achieved a bit over 420 mph.

- Ivan.


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## JtD (Jul 1, 2013)

tyrodtom said:


> In my 20+ years of racing, and some experience with supercharged tow trucks, I've found what you said about the importance of intake and exhaust passages to be totally wrong, most of the improvements in horsepower come from increases in intake flow, AND exhaust flow, thru improvements to intake and exhaust passages and camshaft timing and duration. You can't get fuel/air mixture in if you can't get it out.
> 
> And a supercharger isn't as effective with bad intake and exhaust passages. All the same rules apply, supercharged or normally aspirated.
> And I can't believe that drastically changes if the engine is at 10,000 or 20,000 feet in a aircraft.


In an aircraft, it would usually effect full throttle altitude, and power above full throttle altitude.


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## Shortround6 (Jul 1, 2013)

Aircraft engines were pretty high performance engines for their day. They were assembled using a lot of "tricks/techniques" used in racing engines of the time. Especially as the war went on. Cranks and rods were shot peened and polished. Piston sets were matched for weight ( perhaps not as well as a modern Hi-Po engine but then they didn't have digital scales) to an acceptable tolerance, not just any set of pistons of the right number would do. Intake and exhaust ports may already be polished, at least to some extent. 
I don't know about Japanese or German engines but US and British engines were run on test stands for several hours to break them in and provide a final quality assurance, they were run on dynamometers and failure to met a specified power meant the engine was torn down to find out why. Once the the engine reached the airframe factory or repair shops it was up to the factory or shop workers to install the engine correctly. Engine maker was seldom responsible for the exhaust manifold/pipes. But most of those were fairly short compared to car manifolds/pipes and no baffles. 
Intakes could be tricky, being a number of feet of ducting at times leading to the actual engine intake. 

By WW II mistakes in the size of the intake were pretty rare as that had been worked out during the 20s and 30s. Most installations of high powered engines offered the ability of "RAM" air, forward motion of plane created higher than atmospheric pressure in the intake duct at the engine intake. Leaks in the duct could cause a loss of this pressure but this would only really affect the engine power at speed and at altitude.


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## tyrodtom (Jul 1, 2013)

I realize aircraft engines are already high performance engines, but to state defects in the intake and exhaust passages can't have much affect on performance because they're supercharged on very high boost is just wrong.


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## razor1uk (Jul 1, 2013)

Any and all imperfections are more noticeable as the oxygen thins and the power drops at altitude, boosting the intake via supercharging helps with reduce that, but the imperfections and manufacturing differences in castings, parts, machining etc, tyrodtom, are still there at altitude.

So you have worked on tuned high torque engines, so have you been many places and different heights above sea level, or stayed in a similar geological and geographical area with said engines. 

It is truer, when chasing torque, that imperfections are less worry-some, and that in some parts of the intake or exhaust that some slight roughness* can be useful for encouraging some boundary layer turbulence and thus fuel atomisation with reduced fuel pooling, assuming the bore/diameter to flow rate ratios are already acceptable to the evisaged usual speed range of that engine. 

When chasing power though, and in my mind and most others too, its just the same for torque as well, that just dependant on how you tune and set the engine up. 
Power or torque; any misalignemts, imperfections, improper finishes inside the intake and exhausts reduce what gains you have per cylinder, and you really don't want each cylinder having its own character, fuelling, heat soaking and balaning issues, as that would result in a very compromised engine settings to try and get any sort of smooth engine.

Why shoot your self in the foot running a higher boost, to loose a few percent of it with higher heat soakings and fuel usage when a proper 'blueprinting' for example would produce the same power at few percent less boost with the option to have more boost when needed.

Ahem, blueprinting is a modern term for hand made/balanced/fitted to specs or to a certain standard. In WW2 and industry prior to then and in some places still, this largely didn't exist, so long as the parts were in tolerances, they'd just be slung together so to speak, and hence in a worsening home war situation, some worked well, others were dire.

*There are recent studies into the micro flow of fluids (both liquid and air) around 'dentines' like surface - aka akin to the dentines that form the skin of a shark, increasing the flow smoothness and lowering a sharks (or skates) energy consumption.

When it comes to speed or war, you want all you can get when you need it, and anything less than suitable just isn't right and somebody should get a rollocking for it.


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## fastmongrel (Jul 1, 2013)

Would a poor intake/exhaust design have more effect the higher the altitude. For example I believe Bristol Hercules had a poor design of intake compared to the Hooker redesigned Merlin intake but as the majority of Hercules engined aircraft were used at low and medium altitude this restriction didnt effect performance.


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## Shortround6 (Jul 1, 2013)

It affects performance but the effect was known. That is to say that a Hercules engine performed as the factory said it would, not hundreds of HP less than the factory claimed. Now Bristol may have wondered WHY the RR engines performed better at high altitudes 

These engines _DEPENDED_ upon their superchargers for performance. A poor supercharger hurt performance everywhere but was more noticeable at higher altitudes. The supercharger itself was made up of several components. A poor inlet restricted airflow to the impeller. At sea level this may not be important as the supercharger can provide more boost than the engine can use anyway. BUT the supercharger has to work a little harder, Superchargers at the time were around 65-75% efficient which means that a poor supercharger was using 60-70% of the input power to actually compress the air. A good supercharger was over 70% most of the time. The EXTRA 30-40% was turned into heat (or all but 1-2% that went into friction in the gears and such) and this was the bugaboo. A hotter charge is more likely to detonate, a hotter charge is less dense so even at the same pressure it has fewer pounds of air per minute running though the engine and thus less power. 

Now if hypothetical engine "X" needs 60 hp to compress the air it needs at sea level and the supercharger is 60% efficient you need 100hp going into the input shaft ( forget friction) and 40 hp is heating the intake charge _over and above_ the heating that would take place from compression alone. If you improve the intake entry of the super charger ( and fiddle with the impeller?) and get the efficiency to 70% you only need about 86hp going into the shaft and have ONLY 26HP turning into extra heat. Only 65% as much power going into excess heat. 

Now with a 1000hp engine at sea level the difference of 14hp going to the supercharger is not going to be real noticeable but perhaps the cooler, denser charge will be? 

Most, if not all, of these supercharger intakes were castings and many had the carburetor mounted on them so making trial versions was difficult (expensive) until somebody else showed that better performance was possible. Hooker had a number of claims to fame, one of which was realizing that some of the formulas used to design/evaluate superchargers were wrong. 

And until better than 87 octane fuel came along engines were limited to 6lbs or under of boost (many 1930s engines used 2-3lbs) most any supercharger could provide the performance required. 

And again, the intake of the supercharger is made by the engine maker while the ducting leading to the engine is made by the airframe maker ( in co-operation with the engine maker at times, R-R having an airfield where trials were carried out to try to solve installation problems).


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## fastmongrel (Jul 1, 2013)

Nice one SR6 but you really dont belong on the internet with all these clear concise posts that even a bonehead like me can understand


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## GregP (Jul 1, 2013)

Hi Tyrodtom,

I am assuming, possibly incorrectly, that most of your supercharger experience has been either with automotive engines or possibly general aviation engines of relatively low displacement. Say, 580 cubic inches or less. If I am wrong, I apologize right now. In those engines, the finish of the intake and exhaust manifolds is important for best performance given the relatively small superchargers and displacement involved. That doesn't mean they can't produce great power, but it means the tricks are different. An NHRA Top Fuel engine makes more power than any Reno racer, but wouldn't last for the takeoff run much less for the climbout and race.

In the case of boosted large-displacement aero Vee engines, such as a Merlin (smallest), Allison (middle), or a Daimler-Benz 6 (biggest), the supercharger is moving enough air at enough pressure that the finish is barely noceable in performance. You might see a very slight improvement, but not enough to matter to anyone. In the case of big radials, the supercharger doesn't have to move the air very far and the pressure will make the finish of the intake and head passages irrelevant.

Now it is not entirely immaterial, just largely. If you are racing, every little bit helps and yes, they do it all for racing. But if you are flying a restored Bearcat ... then the difference between 2,135 HP and 2,150 HP is nothing, relatively speaking. If the boost on your R-2800 is 60 to 75 inches of Mercury (15 to 22 pounds for you British boost users), then you won't notice a performance difference after polishing the intakes or exhaust manifold passages in the head.

If I were doing an engine for myself, I'd probably smooth all the head passages ... just for the sake of doing it. But I'd not see any more power than one left essentially stock. The intake and exhaust passages in the head came from the factory smooth enough to make rated power, and are still smooth enough to do that today. When racing at Reno, the extra power comes from a lower compression ratio, higher boost, and higher rpm, not from smoothing the head passages. "Porting and polishing" are meaningless to a Merlin or Allison (balancing is another story). The 3,850 HP in a top racing Super-Merlin comes from taking the 65 inches of Mercury manifold pressure to 125+ inches and from raising the rpm from 3,000 to 3,400 or even slightly higher. An engine is really just an air pump. Move more air and you make more power.

Of course, it had better be running shot-peened Allison G-series rods and had better have a good ADI system and a spray bar or it won't live for very long at full power. Might not even GET there before blowing up. Stock Merlin rods aren't designed with enough of a safety factor to handle more than about 2,500 HP. That level was sufficient for all wartime Merlin use and it still suffices for all warbird use other than racing at the top level in Reno. 

Most of the Bronze and Silver class birds don't need anything more than that. Only if you are running in the top 3 in Unlimited Gold will you need a Super-Merlin or Super R-3350. We'd love to put a racing Allison in one, too, but someone has to want to do it. Also, they don't even use anywhere NEAR full power until the final race. Nobody wants to blow his super-Merlin in a heat race! During race week they start flying about Tuesday or Wednesday, and the only full-power runs happen in the final race, when it matters. All the rest of the heats and races are just to get to the final race.

Then the dirty little secret of Reno Unlimited air racing surfaces. The strategy at the highest level is to win the Unlimited Gold Final at the lowest possible speed, thus saving the engine for next year. Typically, someone will jump out to a good lead and then slowly back off every few laps until they are running somethin like 85 - 90 inches on the last lap, and they only push the go-fast lever in again if somone is catching them. If they could get away with it, they'd win at 300 mph! Only competition makes them go faster than cruise power. By way of example, Steven Hinton Jr. can turn laps in the 515 mph range at Reno (on the old course), but won last year at 477.5 mph. So he probably flew the last lap at 460 mph or so since he qualified at 493.3 mph on the new course.

I notice this IS off-topic and if you want to discuss it further, maybe we should revisit a Reno thread or start a new one. I am not up on the engine hot-rod tricks for the jet class, but I'm sure FlyboyJ is since he is a team member on a jet team. I doubt if he'll tell you all the tricks in any case since they are still racing! Naturally, they do all the drag-elimination things they can to start with. But more thrust and a good smooth racing line are probably the real secrets beyond the aerodynamic clean-up.


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## tyrodtom (Jul 1, 2013)

But the question is how refined was the intake and exhaust passages of Japanese engines as they were produced.
American and other allied engine manufactors usually had the time to optimize their engines, then quality control that insured that the majority of the engines produced met acceptable standards. 
But did the Japanese ?

I'll bow to your expertise when it comes to large aircraft engines Greg, because I have zero experience when it comes to anything over 500 ci.


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## GregP (Jul 1, 2013)

The ONLY experience I have with a WWII Japanese Aero engine is with the Planes of Fame A6M5 Model 52 Zero. It is a Sakae 21 and the quality of the parts matches anything I have seen on an American or British engines of similar vintage. That is to say, excellent.

If they DID suffer quality issues, it was probably with the assembly and bearing clearances or perhaps with the metal alloys themselves. But the fit and finish of the Japanese engines I have seen is excellent. Even the engine in our Mitsubishi Radien is quite good, though unrestored.

I would think the main possible quality issues would be with bearing clearances, possibly ring end gaps, fitting the rings upsides down maybe (causes excessive oil consumption and fouls plugs), and other issues of assembly. It is also possible the rubber parts were substandard and cracked easily, causing leaks in either intake or exhaust paths. 

I do NOT know that the fit and finish were ever bad.

Another issue might be quality control in the carburetors. A great engine with a bad carb comes across as a bad engine.

Wish I knew more about the so-called Japanese quality issues with their engines later in the war. Seems like a good thing to go look for ...

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## Shortround6 (Jul 1, 2013)

On some of their engines the cooling fins were finished by hand on the heads. They were used to hand ( or hand held) finishing grinders. Unless they were incredibly sloppy there shouldn't be enough difference in the port passages to make a several hundred horsepower difference. Cadillac made parts for Allison like connecting rods an aircraft rods had around twice as many inspections as Cadillac car connecting rods and Cadillac was a quality car maker in the 1930s. Aircraft engines, even small, low powered ones, were in another class of manufacture than 99% of the worlds car engines in the 1930s. I am not saying bad parts were not made but it takes an awful lot of people looking the other way to actually get them into an engine. It takes an awful lot of screwing up to have an engine make around 75% of it's rated power. not finishing the intake or exhaust ports isn't going to make that much difference. Aircraft heads do not have the amount of "extra meat" that car heads often do. It is not a question of opening them up for _extra_ flow but just finishing them off, de-burring if you will. Quality may very well have slipped near the end of the war but loose pistons (or bad rings) might make more sense than poor airflow through the ports.


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## GregP (Jul 1, 2013)

I agree Shortround. The parts in the WWII Aero engines I have seen "up close and personal" are universally of very good quality. 

I HAVE seen great parts poorly assembled to produce an engine that needed help rather quickly once it started running. I have seen overhauls last for an entire 5 - 10 hours! Nothing wrong with the parts, but the clearances were simply ignored and the engine self-destructed in normal operation. Perhaps the Japanese experienced a lot of poorly-trained operators at the engine plants later in the war? As I said, makes me want to look into it .... but where to start ....


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## bobbysocks (Jul 2, 2013)

the beauty and magic of the old norton engines was how well they were ported...which was damn near perfect. i know a guy who races triumph motorcycles....he claims he can gain me 5+ hp with his port job on my bonneville. the better an engine breathes supercharged or not has to have some effect on performance.


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## GregP (Jul 2, 2013)

Normally aspirated, yes. Once you get boost in a big engine, it is realtively meaningless. I am, of course, assuming decent surfaces from the factory. As I said, in WWII the factory surfaces were sufficient to obtain full power. That is, I'm not talking about very rough finishes to start with. Rather, factory smooth passages.

In a small, normally aspirated engine, the air enters at only atmospheric pressure, 29.92 inches of Mercury on a standard day, and smoothing can help quite a bit. Hence "porting and polishing" are a good thing, and I've done a few myself. I had a particularly good result on a Suzuki GS 1000 once.

In a big supercharged engine (the bigger the better), the air is being forced in and a decent surface is all that is needed ... and they all had that straight from the factory. Once you start boosting, the power comes from moving more air. Higher manifold pressure and rpm does it best, and does WAY more than smoothing an already decently smooth head passage.


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## fastmongrel (Jul 3, 2013)

bobbysocks said:


> the beauty and magic of the old norton engines was how well they were ported...which was damn near perfect. i know a guy who races triumph motorcycles....he claims he can gain me 5+ hp with his port job on my bonneville. the better an engine breathes supercharged or not has to have some effect on performance.



A port job will certainly help your Bonnie breathe better but 5+hp gain. Mmm not sure about that not without some other work. My BSA Thunderbolt has been tweaked over the years with a balanced crank, ported head, CV carb conversion, electronic ignition, oil cooler and a belt primary drive and I reckon all that has raised power by about (Holds finger and thumb up) that much. Where porting does work is in the mid range on Brit twins, the Thud was always a torquey beast but now it can shame a Jap 600 up to about 60mph. Of course at 60mph the rice boiler goes past like I have hit the brakes 

I used to race classic bikes and it was all about getting it to rev and not spew oil and engine parts all over the track not about peak power on a dyno. The original Fastmongrel was an Aermacchi 350 flat single that was bored out to 408cc and wrapped in a Drixton frame. It was fast for a pushrod aircooled motor and you could go hunting TZ250s on a twisty track but the engine quite often went home in a bucket. I detuned it with a new piston and a new cam and it became a beauty to ride but was never in danger of catching a 2 stroke on the straight.


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## Shortround6 (Jul 3, 2013)

Porting can help set the engine up for different things. Ford got carried away at times with huge ports on both the 351 Cleveland engine and _some_ special 427 heads. Great for power at 6000 rpm and above but they actually hurt the engine/s down low. For street use the smaller port heads were actually better. The huge ports had too much volume and reduced the velocity of the incoming gas at low rpm ( low gas flow). 
This is not the same as just smoothing things but often a good port job also changes the angle or curve inside the passage. 

And again, what works very well on a rough, small cast iron port may have less benefit on a port that is already about the right size and somewhat smooth (less improvement since you are already halfway there).

Un-supercharged engines have _less_ than atmospheric pressure in the intake manifold/ports. Gauges hooked up to the manifold of such engines are vacuum gauges and show how many inches _less_ than normal the pressure is. 

The downward moving piston is creating a low pressure that sucks the air through the engine instead using a pump to force the air in. Smooth passages, gentile turns and large cross sections can help but the force feed engine does have different conditions. 
One of which is that it already can flow more air than the engine can use _until_ it hits full throttle height.


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## cherry blossom (Jul 3, 2013)

The consensus here seems to be that it would be hard for the likely “quality control” problems to reduce the power of the Homare 22 from 1750 hp at altitude to an estimated 1300 hp. The founder of Nakajima was a politician Chikuhei Nakajima - Wikipedia, the free encyclopedia and I suspect that they did not undersell their products. I have zero evidence but is it possible that the Homare was redesigned over 1944-5 along the lines of Hooker's improvement of the Merlin over 1940-1 crucially without changing the model designation? A possible motivation for such apparently bizarre behaviour might be that the high power had already been falsely claimed for the initial models 21 and 22. Thus calling the redesigned models by the same names and blaming quality control problems could allow Nakajima to avoid accusations of fraud.

ps. If the Homare 21 of 1944 gave only 1300 hp at altitude, it makes it clear why the lighter Ha-112 II giving 1250 hp. at 5800 m. at 2600 rpm could replace it in the Ki-116 and give similar performance to a standard Ki-84 (but presumably not matching the later American tests).

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## GregP (Jul 3, 2013)

The gauges are not vacuum gauges, they are pressure gauges. 

Get into a normally aspirated, carbureted aircraft. Assume the air pressure is at 29.92 unches of Mercury, which you can easily verify by dialing in the field elevation. With the engine off, you'll read 29.92 inches of Mercury, atmospheric pressure ... assuming the field is at sea level. If not, you'll read about 1 inch per 1,000 feet less. So, at 6,000 feet with the engine off, you'd read about 23.90 inches of Mercury before you start the engine.

On takeoff, at full power, you'll read about 1 inch less than ambient presure since the throttle plate is in the flow path. Once you get some speed, you usually regain this lost inch and maybe a little more due to ram air pressure being added to the ambient pressure.

At idle, you'll read about 12 inches or so because the throttle plate blocks the air passage and the pistons create a partial vacuum, but the gauge is reading air pressure in the intake, not vacuum. In a supercharger or turbocharged engine the gauge is still reading pressure.


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## Shortround6 (Jul 3, 2013)

They may actually read "pressure" but most _CAR_ gauges on _UN-SUPERCHARGED_ engines are commonly referred to as vacuum gauges and are marked as such on the dial by their makers. Some are calibrated at "0" (normal atmospheric pressure) and work backwards. 












Some gauges will show both positive and negative pressure and are called boost gauges. 






_AIRCRAFT_ manifold pressure gauges are as you describe. 






Again we have to be careful it trying to compare auto or motorcycle practice/experience to aircraft use.


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## fastmongrel (Jul 3, 2013)

GregP said:


> The gauges are not vacuum gauges, they are pressure gauges.
> 
> .



I work as a car(auto) mechanic and I use a Vacuum gauge and a normal healthy car engine Blown or not blown will show about 18 to 20 "hg at tickover and if you snap the throttle open and release it will drop to about 5 "hg then bounce back. If a gauge showed a atmospheric or plus reading then the engine probably wouldnt run.


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## GregP (Jul 3, 2013)

All AIRCRAFT manifold pressure gauges show pressure. As I stated, they'll read ambient air presure when the engine isn't running. They read less at idle due to partial vacuum and the closed carburetor plate, but 12 inches is still pressure. The vacuum pulled is the difference between ambient and the reading at idle, which will usually run about 12 inches at idle for something in the 360 - 520 cubic inch range Lycomming. So, it's pulling about 17.02 inches of vacuum against 29.92 inches of pressure ... you still get pressure. All you have to do to make it a vacuum gauge is zero out ambient pressure and you've got it. Nothing mysterious about it.

Shortround, the only aircraft gauge in your group is the last one, and it clearly states on the gauge face that it reads in inches of Mercury absolute. That is a pressure unit.

Here is a good explanation: http://www.advancedpilot.com/downloads/prep.pdf


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## bobbysocks (Jul 3, 2013)

you are arguing semantics....it is pressure in the fact it is show you the difference between the ambient air pressure in the manifold vs that of an absolute vacuum. suction vs lack of pressure. right from that website..

*Suction, Not Pressure
First, let's get rid of this idea of "pressure," because what the MP instrument of any normallyaspirated
engine really shows is lack of pressure. In short, with the engine running, the MP gauge
is always reading suction -- it's just marked with numbers that don't make that obvious.*

*It should be clear from this that the intake system of any normally-aspirated engine is nothing
more than a vacuum pump!*


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## GregP (Jul 3, 2013)

Yup, there is vacuum on the piston side, but not complete. The 12 inches of pressure inside the intake at idle is exactly that pressure. It is about like being at 20,000 feet. So the pressure difference creates airflow and the venturi feeds the fuel.

As I stated, the gauges in an aircraft are pressure gauges, not vacuum gauges, Go sit in any Cessna, Piper, Mooney, Beechcraft, etc. You won't see an engine manual that specifies vacuum ... they specify inches of Mercury absolute of manifold pressure, not inches of vacuum.

Now, it is true, you CAN retrofit a vacuum gauge and operate it that way if you write your own manual, but you won't buy it that way from a certified manufacturer.

Might be semantics, but you might as well get it right.


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## bobbysocks (Jul 3, 2013)

i have sat ( and flown ) cessnas, pipers, and stinsons. yes, they all had manifold pressure guages.....that showed the reaction of suction to the ambient air. 

2a: the act or process of exerting a force upon a solid, liquid, or gaseous body by reason of reduced air pressure over part of its surface


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## GregP (Jul 3, 2013)

When I think a vacuum, I think if testing we did at Motorola down to levels of 10 Torr, not 12 inches of Mercury. To each his own, I guess ...

And yes, it is semantics. A "vacuum pump" in an aircraft doesn't create a total vacuum, it creates a partial cavuum to develop a p[resure differential and run gyro instruments, so you could look at it as vacuum .... but then again, when you test a vacuum pump, you usually use a vacuum gauge, not a pressure gauge. In reality, all you are doing is testing the magnitude of the pressure differential so you can ensure there is enough delta to run the instruments. You could do it with an air compressor, too, but they usually don't for obvious reasons. 

Whenever I used to have to buy a vacuum pump, I'd think about that ... and then order the damned vacuum pump anyway ... and curse it until I was flying again. For some reason, Hobbs meters tend to be an issue, too. Must be phases of the moon since nobody was smoking in any planes I flew. Luckiy I had very few actual engine issues ... the only failure I had was in a rental C-172 and it was a partial failure. Somebody had put sugar in the gas tank and I lost power but was able to restart and keep it running using the primer until I got to an airstrip. Then I called the flying club and told them to come pick up both their airplane and me.


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## Ivan1GFP (Jul 7, 2013)

I know we are playing a semantics game here, but what would you call a Japanese or British manifold pressure gauge?
The readings are relative to ambient pressure.....

- Ivan.


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## GregP (Jul 7, 2013)

The British used pounds of boost and used what is essentially a vacuum guage. The same engine in the P-51 uses a manifold pressure guage. I never said you C'T do it, I said it isn't common, especially today.

You CAN use either guage but, here in the USA, you can't find one from a manufacturer with a vacuum giage. In Europe (or anywhere else) today, if you are flying a Piper or Cessna, you are flying a manifold pressure guage.There may well be some European manufacturers who purchase Lycomming or Continental engines and use them with boost guages in their planes, I don't know. If they do, then they are responsible for the engine manual. Most manifacturers use the system developed for use with the engines they source and don't "re-invent the wheel."

The Germans used manifold pressure referenced to technical; atmospheres. Thye Japanese and Soviets used either mm of Mercury manifold pressure or sometimes the German ata (technical atmospheres) unit. Of all the WWII combatants, only the British used a boost (essentially a 2-way vacuum gauge) gauge. When properly calibrated there is no difference and you can convert the units easily. It's just that most of the world uses pressure, not vacuum. If anone just has to use vacuum, by all means vacuum away.


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## GregP (Mar 6, 2014)

If anyone is interested, I can post the formulas to conver among the manifold pressure units. It's easy in a spreadhseet, and takes away the uncertainty.


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## Aozora (Mar 7, 2014)

bobbysocks said:


> the beauty and magic of the old norton engines was how well they were ported...which was damn near perfect. i know a guy who races triumph motorcycles....he claims he can gain me 5+ hp with his port job on my bonneville. the better an engine breathes supercharged or not has to have some effect on performance.



My great uncle owned a motorbike he claimed had a Triumph engine in a Norton frame, but I can't remember what it was called; was there such a bike (pardon my ignorance here)?


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## GregP (Mar 7, 2014)

Not too sure about the name, but it would have been the best of both worlds at the time ... though the Norton engine wasn't far behind. Trumpets were quick for the day and light, but the Norton frame and swingarm didn't flex near as much as the Triumph did. NOTHING else flexed like the old 2-stroke Kawasaki 750 triple and the original Kawasaki 900, though ... except maybe the Suzuki 500 twin.

Must have been beer can-grade steel and plastic swingarm bushings(not really).

You'd still have to put up with the Triumph oil leak becasue the oil leaked through the engine case, not from around the gaskets or seals ... the Aluminum was too porous and once the bubbles in the Aluminum filled up with oil ... it sort of migrated to the ground via the bottom of the engine case. Nothing you could do about it. It weeped all the time.

Not too fond of the old carbs either, but fuel injection for bikes wasn't around yet, so they were about near the top of the heap despite the issues. The Tiger and Bonneville were pretty good except for the shifter and brake being on the wrong side. It never got in the way until an emergency, and then you always downshifted whether or not you wanted to do so. Caught me a couple of times and I didn't go down, but it was dumb luck I didn't. 

The new ones don't leak through the engine cases (or anywhere else for that matter) and are genuine 150,000 mile motorcycles ... or maybe more. I have one friend with 180,000+ on a new build Triumph with normal maintenance ... but he isn't a racer, just a street rider.


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## razor1uk (Mar 7, 2014)

To keep with the motorcycling sub topic, the 'Bloor' triumphs, built at Hinckley, the original (mid to late) 80's era engines were based upon the mid 80's Kawasaki GPZ900 AFAIK, with enough differences to not cause patent conflicts - like 3 cylinders (except for the 1200 4's used in the Trophy/Daytona 1200) and differing dimensions of bore stroke, crank throws, rod lengths, distances between the inlet and exhaust cams to the crank etc.. 

The newer 509 and other new Triumph engines should be just as good - I love the 675 Triumph motor, it partially inspired the new 'MV' to make a baby triple...

Well Kawasaki might have not been to bothered too much, since their original Meguro name W6 (or W12?) was almost a pure copy in ethos to a BSA (AMC) A6/10 with some Triumph alike engine details, both the English engines I believe, were Edward Turner designed; or as Chief Engine Designer/Engineer the 'signer-off' for the work the engine team did most of the Brit twins engines for most of the 30's - 60's British manufacturers at one time or another.

So the Hinckley ones with regular servicing, should be capable of theoretically GPZ900 ZZ1100 heard-of milages of over 200,000 engine-wise.


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## Gixxerman (Mar 7, 2014)

GregP said:


> Not too sure about the name, but it would have been the best of both worlds at the time .



AFAIK they were commonly referred to as 'Triton's' (certainly all the mags I've read here use the term often).



GregP said:


> NOTHING else flexed like the old 2-stroke Kawasaki 750 triple and the original Kawasaki 900, though ... except maybe the Suzuki 500 twin.



The weird thing is many reviews these days often say they're not that bad, nothing like as good as the modern stuff of course but I always had a feeling that for journo's riders used to British Italian machinery the big Japanese 2 strokes were so different they got a bad name.
I was raised on them (although the Kawasaki H1 500 H2 750 were bikes I never got the opportunity to sample) but I rode and/or owned all the other Kawasaki triples the Suzuki GTs at one time or another. If you were used to them ( carried out a couple of simple mods - decent shocks were a must) they weren't that bad.
Funnily enough I did try out a BSA A65 Lightning once to me it was the different one with odd feel.



GregP said:


> The Tiger and Bonneville were pretty good except for the shifter and brake being on the wrong side. It never got in the way until an emergency, and then you always downshifted whether or not you wanted to do so. Caught me a couple of times and I didn't go down, but it was dumb luck I didn't.



Ah but to us over here it was, back then, the correct side...although obviously as Japan's influence the demands of the US market became a big factor we changed.
I know what you mean tho Greg, if you're used to a left-foot gear change right brake it can be downright dangerous, as someone used to your layout pattern on Japanese bikes riding older British machinery was um 'interesting' sometimes because of it.
I suppose if you owned one for a while it would just become 2nd nature. 



razor1uk said:


> To keep with the motorcycling sub topic, the 'Bloor' triumphs, built at Hinckley, the original (mid to late) 80's era engines were based upon the mid 80's Kawasaki GPZ900 AFAIK, with enough differences to not cause patent conflicts - like 3 cylinders (except for the 1200 4's used in the Trophy/Daytona 1200) and differing dimensions of bore stroke, crank throws, rod lengths, distances between the inlet and exhaust cams to the crank etc..



Indeed, modular design was their objective a pretty sound strategy at that.
Choosing a sound design for basing their initial models (the GPZs you mentioned are undoubtedly where they began) has indeed led to excellent reliability coupled with good performance.
Not at all bad considering what they started from.

In reference to GregP's comment about porous alloys I have read that the Bloor manufacturing used a resin to seal the alloy as they were manufactured.
I have never read anything other than they were ( continue to be) as good as anything out there, finally the jokes about 'Royal Oilfields' and so on are a thing of the past  



razor1uk said:


> The newer 509 and other new Triumph engines should be just as good - I love the 675 Triumph motor, it partially inspired the new 'MV' to make a baby triple...



Not a bad compliment, eh?
I think they also influenced Benelli with their Tre900 triples too.


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## parsifal (Mar 7, 2014)

Im surprised no-one has mentioned the Kyushu J7W Shinden. Admitedly a prototype, but it did fly during the war

Performance

Maximum speed: 750 km/h (469 mph)
Range: 850 km (531 miles)
Service ceiling: 12,000 m (39,360 ft)
Rate of climb: 750 m/min (2,460 ft/min)
Wing loading: 240.4 kg/m2 (49.1 lb/ft2)
Power/mass: 0.32 kW/kg (0.20 hp/lb)
Armament


Guns: 4× 30 mm Type 5 cannon
Bombs: Up to 120 kg (264 lb) bombload


_View: https://www.youtube.com/watch?v=hJs1O2HSosE_


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## Shortround6 (Mar 7, 2014)

Aozora said:


> My great uncle owned a motorbike he claimed had a Triumph engine in a Norton frame, but I can't remember what it was called; was there such a bike (pardon my ignorance here)?



They were called "Tritons"

Triton motorcycle - Wikipedia, the free encyclopedia


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## razor1uk (Mar 7, 2014)

The beautiful Kyushu J7W Shinden; 'though it had cooling issues with its engine - possible an ex raiden/jack 'long case' unit. 

Certainly it is a craft of 1946 'what if ' candidate for top spot - although the flying prototype wasn't armed AFAIK. There's likely to be one rusting away in a Smithsonian hanger somewhere if it wasn't recycled.


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## GregP (Mar 7, 2014)

As far as I know it made exactly two flights, both with the same pilot. The aircraft vibrated fiercely (probably the long drivesahft but maybe an unbalanced prop) and was never flown again. I'd be hard-pressed to say it was even close to flightworthy. So maybe it had potential, but wasn't ready for anything when the war ended. Perhpas it could have been developed and perhaps not ... I don't know.

Looks futuristic, but I could not say whether or not it would have been even a passable service aircraft. Maybe a jet version ... and maybe not. I like to think it could have been developed but that would be venturing into the realm if a "what-if," and I usually decline to go there because there are no answers that can be shown to be right or wrong with historical fact, so anything can be claimed.

At lest we know the Me 163 / J8M flew well when powered by rockets. That makes me suspect they would fly well with a jet engine, too, but nobody can really say. They never made one.

Still, I like the J7W and hope it could have been made to work.


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## Aozora (Mar 7, 2014)

Shortround6 said:


> They were called "Tritons"
> 
> 
> _View: https://www.youtube.com/watch?v=hJs1O2HSosE_
























The engine installation:


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## Milosh (Mar 7, 2014)

The de Havilland DH 108 was very similar to the Me163.
de Havilland DH 108 - Wikipedia, the free encyclopedia


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## GregP (Mar 7, 2014)

I think of the DH 108 as a flying drop tank ... and have heard it described that way by British test pilots in print.

I wonder if, using today's design software, it is possible to "fix" the DH 108 so it flies without dangerous high speed tendencies. It probably is and we'd probably find the airfoil to be the primary culprit ... the issue was probably where the shock waves started when the critical Mach number was reached. Too bad John Derry and Geoffrey de Havilland had to find out the hard way. They were two of the good guys.


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## DVH (Mar 8, 2014)

I have a soft spot for the ki 61. Most japanese fighters were, in appearance at least, variations on the same theme. No wonder allies referred to the zero in a catch all term. 
Seems that the ki 61 broke the mold, even if it was a derivative of a german design. It was a beauty. Shame none are flying today.


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## Garyt (Mar 10, 2014)

I'm responding to some earlier posts regarding the US planes always being heavier than the opposition.

Was it perhaps a question of resources? The US certainly had more to burn than any other country, being economical with their usage of their resources was not as issue.

What was the cost per plane on say a p-47 or p-38, even a p-51 compared to other nation's 2nd generation fighters?

I this regard I think the Germans did great, took the Me109 that was there at the very outbreak of the war and kept it competetive with other designs til the end of the war. Little lost in re gearing production lines. It was also a relatively small craft, I would think not overly expensive on a per plane basis in comparison

But if you have a huge lead in available resources, and you can make a plane that might be 50% more costly in resources, but gives you a 10% advantage in performance, it makes sense.


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## CORSNING (Mar 11, 2014)

The 109 wasn't escorting heavy bombers 500-600 mls. one way.


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## Shortround6 (Mar 11, 2014)

Garyt said:


> I'm responding to some earlier posts regarding the US planes always being heavier than the opposition.
> 
> Was it perhaps a question of resources? The US certainly had more to burn than any other country, being economical with their usage of their resources was not as issue.
> 
> ...



The US didn't build large fighters _because_ it had resources to burn and thus could be wasteful. You can't repeal the laws of physics just because you have more resources and American designers had to obey the laws of physics ( gravity, airflow/resistance, etc) just like any other countries designers. 

P-38 was designed the way it was because the _initial_ specification called for _twice_ the endurance of the P-39 which was built to a different but similar timed specification. If you want the _same_ speed and _same_ climb while carrying the _same_ armament but you want to do it for *twice* as long you need a lot more fuel which means more weight which means more wing which means even more weight which means more power which means...............

American aircraft often carried a greater wight of armament ( I am not saying better, the .50 cal gun was heavy and it's ammo was heavy) and had more range. The range is understandable given the the size of the US. If you build small short ranged fighters you need a lot more of them to cover the US coast. Which is cheaper, the bigger longer ranged planes or many more smaller planes? 

The Germans kept the 109 "competitive" by reducing it to a one trick pony. While it could still do useful work in 1944/45 as a short range/local interceptor (something the Germans did need a lot of) it was a lousy fighter-bomber/strafer by 1944 standards, it would have been a lousy escort fighter, it wasn't even a really good bomber interceptor being too lightly armed in the 3 gun configuration and loosing performance in the 5 gun configuration ( climb and turn). 

British '2nd Generation' fighters may include the Typhoon and the Tempest which I doubt were really that cheap.


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## fastmongrel (Mar 11, 2014)

I bet Sabre engines cost a packet you could probably get 3 Merlin 60 series for the same money


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## DonL (Mar 11, 2014)

You can also look at the FW 190 D-9 and Tank 152, they are in the same weight and external dimensions class.
THe FW 190 A is a little in between but clearly larger the a Bf 109.


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## BiffF15 (Mar 11, 2014)

I concur with Shortround. 

Planes are built to specifications. The F15 was built around the radar, with the add on of carrying 8 missiles. Yes, it's bigger than most but not the biggest. In my opinion the bigger the plane the further it will go, and to some extent the less maneuverable it will be. The smaller it is, the more maneuverable it should be (less mass to move around). However, you couldn't go to Berlin and back with a Spit (or Berlin to London with a 109), but the Mustang could. In modern parlance the Mustang is a Interdiction fighter while 109 is a point defense type of fighter.

If you are fighting close to home the point defense fighter is preferred, it's usually more of a hotrod from the pilots perspective. Key word is "defense". If you are going deep (on the offense), the Mustang / Lightning (w/drop tanks) would be choice as you can take the fight to his capital, fight for a while, then come all the way back home.
My opine only...
Cheers,
Biff


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## Garyt (Mar 11, 2014)

A lot has been said stating the reason for larger American planes was due to the need for range. To counter this, look at the Japanese planes. Great range, light planes by american standards. So no, it's not just the need for range. There would be ways of keeping the planes smaller and still having good range.

"The Germans kept the 109 "competitive" by reducing it to a one trick pony. While it could still do useful work in 1944/45 as a short range/local interceptor (something the Germans did need a lot of) it was a lousy fighter-bomber/strafer by 1944 standards, it would have been a lousy escort fighter, it wasn't even a really good bomber interceptor being too lightly armed in the 3 gun configuration and loosing performance in the 5 gun configuration ( climb and turn)."

I agree here with it's limited role, but as you say that is what they really needed at the time. With the 30mm and to 12.7's, it was more formidable against bombers of course, but lost a bit against other fighters. And the 5 gun packed a heck of a lot of firepower - and if it could limit it's opponents to enemy bombers it's climb and turn would not be a huge issue. Of course, that's a perfect world for the 109, but I would think the 5 gun 109's would be focusing on bombers.

And really, for other roles the ME109 could have been modified for larger drop tanks. Agreed, it's small frame would not work well as a fighter bomber, and it would not be great at carrying ordinance. But in the air to air role, it went from 1939 to 1945 and was still competitive in 1939. That's not something that can be said by the P40, P39, Wildcat, Buffalo, Hurricane, Claude, Oscar or Zero.

But still, I don't think anyone has answered the question as to the costs of the various planes. I'd think 2 Me109's, given the Germans needs at the time, would be far superior to having say 1 P51. And this is not even including the costs of refitting to produce a new line of aircraft.


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## GregP (Mar 11, 2014)

The cost of US warplanes varies greatly depending on when you bought it,

Let’s take a snapshot in 1944:
1) P-51: $51,572.
2) P-38: $97,147.
3) P-47: $85,578.
4) P-61: they didn’t buy any in 1944. It was $649,584 in 1941 but had dropped to $180,711 in 1943.
5) P-80: $109,471.
6) A B-17 was $301,221 in 1941 but was $187,742 in 1945. In 1944 it was $204,370.

I have some German data for 1941:
1) Bf 109E: 85,970 RM. This converts to $34,388 USD. 
2) Bf 110C: 210,140 RM. This converts to $84,056 USD.
3) Ju 88A: 306,950 RM. This converts to $122,780 USD.

In 1941 we didn’t HAVE a P-51, but:

1) P-38: $134,284,
2) P-40: $60,562.
3) P-47: $133,246.

So the Germans could field 3.9 Bf 109E’s for every P-38 we had in 1941 (by cost, anyway) … but we could not fly any mission with a Bf 109 that the P-38 flew other than training missions. The Bf 109 simply didn’t have the range, so it was never going to be an Allied option.

The Bf 110 was not anywhere NEAR the fighter that the P-38 was, but the Germans could by 1.6 of them for every P-38 we had. The Ju 88 was about a wash, close to 1 for 1.

In the end, the Germans had a great little plane in the Bf 109, but it would not have been possible for the British or the USA to use it for very many missions due to limited range, so it would never be an option for us … but it WAS cheaper by long shot.


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## DonL (Mar 11, 2014)

> In the end, the Germans had a great little plane in the Bf 109, but it would not have been possible for the *British* or the USA to use it for very many missions due to limited range, so it would never be an option for us … but it WAS cheaper by long shot.



Where was the Spitfire much different from the Bf 109 from the outer dimensions and the general design, design goals and especially the range?


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## GregP (Mar 11, 2014)

Hi DonL,

You are correct, I was thinking of the missions the Americans were flying.

For home defense of Great Britain, it would have done just fine. In fact, the Spitfire and the Bf 109 were interchangeable in short-range, point defense missions.

But neither was going to suffice for bomber escort, deep interdiction (as in Britain to Germany and back), weren't much use in the MTO except for short missions, and were hopeless for the PTO except in point defense fighter missions. We had a few of those, but not many in the PTO. One place where they would have done fine was support of armor in North Africa. The forward airfields could easily have been close enough for the Bf 109 and the Spitfire to have supported ground actions.

By the way, the Zero managed long range by eliminating all the pilot protection and aircraft armor, not something we were going to do, so the larger size of American fighters was necessitated by requirements.


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## tomo pauk (Mar 11, 2014)

Spitfire was definitely bigger. The wing area was 242 sq ft, vs. 173 sq ft. P-51 was at 235 sq ft.
Big wing will enable more benign flight characteristics, and will be an asset in high altitudes. It might allow for more room to shuffle new stuff inside, like increased armament, fuel, engines's accessories. Shortcoming is that bigger wing means bigger drag (less speed), provided both wings are of about same generation and thickness. 
We can compare the italian % series of fighters, to see how the bigger of them can carry more, but the smaller perform better. All on same engine.


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## BiffF15 (Mar 11, 2014)

Garyt said:


> A lot has been said stating the reason for larger American planes was due to the need for range. To counter this, look at the Japanese planes. Great range, light planes by american standards. So no, it's not just the need for range. There would be ways of keeping the planes smaller and still having good range..



Yes, there is more to it than range. Think of it as a min equipment list for the US aircraft. Two way radios, naviagtion radios, armor, IFR capable, guns w/good to great loadouts, self sealing fuel tanks, high dive speeds, and also manufacturers were new to "modern" construction techniques (and probably rounded up on anything of question adding more weight). The Japanese replacement for the Zero was the Reppu, and the Germans with the Fw-190D which both had/have weights that were within an RCH of the Mustang. 

To make products that are comparable (able to do the same mission), engineers regardless of their country of origin come up with almost the same product. Look at the F-15 Eagle compared to the Su-27, and the F-18 compared to the Mig-29 (point is it still occurs to this day).



Garyt said:


> The Germans kept the 109 "competitive" by reducing it to a one trick pony. While it could still do useful work in 1944/45 as a short range/local interceptor (something the Germans did need a lot of) it was a lousy fighter-bomber/strafer by 1944 standards, it would have been a lousy escort fighter, it wasn't even a really good bomber interceptor being too lightly armed in the 3 gun configuration and loosing performance in the 5 gun configuration ( climb and turn).".



As was previously stated the 109 attributes make it a short ranged / point defense fighter.



Garyt said:


> And really, for other roles the ME109 could have been modified for larger drop tanks. Agreed, it's small frame would not work well as a fighter bomber, and it would not be great at carrying ordinance. But in the air to air role, it went from 1939 to 1945 and was still competitive in 1939. That's not something that can be said by the P40, P39, Wildcat, Buffalo, Hurricane, Claude, Oscar or Zero.



The P-39, 40, Wildcat, Buffalo, Hurricane did not enjoy the focus of improvements that the Me-109 did. The Spitfire grew in both performance and size by a large amount over it's lifespan, with the late Mk 14's being both leggy and fast. I can't speak to the Claude or Oscar, but the Zero did get improvements over it's lifespan with the 52 being the high point (IIRC). However, (and I'm not an engineer) the Zero was built in the WW1 "maneurvering over all else" mentality and to make it as fast AND as long ranged as the US stuff would have required A LOT of work (hence the Reppu).



Garyt said:


> But still, I don't think anyone has answered the question as to the costs of the various planes. I'd think 2 Me109's, given the Germans needs at the time, would be far superior to having say 1 P51. And this is not even including the costs of refitting to produce a new line of aircraft.



It's my opine that the Germans needed a better pilot training pipeline, established MUCH earlier in the war, to feed it's aircraft production capability as well as it's attrition. They started the war with the most experienced / best fighter pilots and didn't build on that. The US pilot production was the opposite. However they used a constant improvement process over the life of the war (and it's still in use today) to deliver a much better product to the front line.


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## tomo pauk (Mar 11, 2014)

BiffF15 said:


> ...
> 
> The P-39, 40, Wildcat, Buffalo, Hurricane did not enjoy the focus of improvements that the Me-109 did. The Spitfire grew in both performance and size by a large amount over it's lifespan, with the late Mk 14's being both leggy and fast. I can't speak to the Claude or Oscar, but the Zero did get improvements over it's lifespan with the 52 being the high point (IIRC). However, (and I'm not an engineer) the Zero was built in the WW1 maneurvering over all else mentality and to make it as fast AND as long ranged as the US stuff would have required A LOT of work (hence the Reppu).
> ....



The Spitfire did not grew in size by large amount over it's lifespan. Wing remained of about same size, the fuselage remained in the ballpark. Only the vertical tail grew, to enable more cotrol against the increased engine power torque. The Spit 14 was fast, but was not rangy. The predecessor, Mk. VIII, was rangier.


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## BiffF15 (Mar 11, 2014)

Tomo,

I will defer to you. I thought I remembered reading that the late Mk14's had pretty good range. 

I probably didn't use the best choices of words regarding growth. There is roughly a 20% increase in weight from the Mk5 to the Mk14.

Cheers,
Biff


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## GregP (Mar 11, 2014)

Sort of lost the wonderful handling along the way. None of the Griffon-powered Spits were as sweet to handle as the Merlin-powered Spits, according to the pilots, but were climbing fools with power to spare.


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## parsifal (Mar 11, 2014)

relative to its contemporaries, however, even the griffon engined spits were always manouverable. relative to earlier, less powerful and less heavy aircraft, they were not so manouverable


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## GregP (Mar 11, 2014)

True, parsifal. I think the Mk. IX was the best of the bunch for all-round handling and power, but it was outperformed in speed and climb by the Mk. XIV and other Griffon units. But if you were GOING to get into a dogfight, I'd take a Mk. IX over a Mk. XIV.

Just a personal choice, not a knock on the XIV. At least I'd be less likely to nose-over a Mk. IX by long shot.


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## Garyt (Mar 11, 2014)

Thanks for the cost info, GregP. Kind of roughly what I expected, other than it seems US prices went down as the war went on, I would have expected the opposite.

Assuming stagnant German prices, they could build roughly 3 ME109's for a P47 or P38. And I would think a bad economy due to the cost of war would have resulted in some major inflation, I think what I am really trying to get at is the cost in resources, I.E. manpower + materials as opposed to a comparison to currency. So I would think the 1941 German numbers would work well.

"Yes, there is more to it than range. Think of it as a min equipment list for the US aircraft. Two way radios, naviagtion radios, armor, IFR capable, guns w/good to great loadouts, self sealing fuel tanks, high dive speeds, and also manufacturers were new to "modern" construction techniques (and probably rounded up on anything of question adding more weight). The Japanese replacement for the Zero was the Reppu, and the Germans with the Fw-190D which both had/have weights that were within an RCH of the Mustang."

Funny. I thought the Reppu (Sam?) was still a fair amount lighter than US planes. 

"It's my opine that the Germans needed a better pilot training pipeline, established MUCH earlier in the war, to feed it's aircraft production capability as well as it's attrition. They started the war with the most experienced / best fighter pilots and didn't build on that."

Fully agree Biff, though lack of fuel prevents training. Though if they would have started sooner while oil production was still at it's peak, they may have had a lot more sucess. They did not seem to have quite the same problems as the Japanese, who seemed to be having fuel shortage issues almost from day 1.


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## Garyt (Mar 12, 2014)

"Funny. I thought the Reppu (Sam?) was still a fair amount lighter than US planes. "

Well, to my suprise I found out the empty weight of the Reppu was only about 500lbs lighter than the P51.

Interesting to me as well was the fact that the Reppu had about 1.5 times the amount of wing surface area of the P51
.


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## Glider (Mar 13, 2014)

Garyt said:


> "It's my opine that the Germans needed a better pilot training pipeline, established MUCH earlier in the war, to feed it's aircraft production capability as well as it's attrition. They started the war with the most experienced / best fighter pilots and didn't build on that."
> 
> .


I think a similar statement could be made re the IJN. Excellent pilots at the start but the training programme to replace them was far below what was needed


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## BiffF15 (Mar 13, 2014)

Concour!
Cheers,
Biff


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## GingahNinja (Mar 13, 2014)

Performance wise I'm not sure, but I have a soft spot for the Ki-61 and Ki-84 series.


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## Garyt (Mar 13, 2014)

"Best for it's time" May well be the A6M2. It was certainly superior to the Bresters, Wildcats and P40's it ran into.

And I think the A6M2 variant had pretty well run it's course by the time the US next generation fighters came out like the Corsair and Hellcat, though I think the early P38 was around during the end of the A6M2's run, though this was the early version of the P38 as well, not the P38L.

Otherwise I like the KI84, about the fastest, great in the vertical plane, well armed, while not quite able to turn like a Zeke it was still a lot more nimble than the US fighters. Even had the armor and self sealing fuel tanks. Only thing I'm not sure about is whether it had a decent high speed roll.


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## CobberKane (Mar 14, 2014)

The problem with these "What was the best" questions is the lack of context. If the context is "best relative to it's contemporaries" the answer might well be the Zero - better than the opposition for much of it's existence. If the context is in terms of outright performance the answer would probably be the Frank, although it never demonstrated the kind of performance advantage over the opposition as the Zero did pre-1943. Unless we are happy to limit ourselves to a handful of late war designs, to my mind a discussion of the 'best' is most useful if it examines the performance of an aircraft through successive models, with the contemporary opposition as a yardstick. By that criteria, and given the original question excluded the Zero from consideration, the answer would probably be the Oscar. For all it's flaws it was at least as good as most of the opposition for several years. Aside from the disqualified Zero, what other Japanese fighter could make the same claim?


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## Thorlifter (Mar 14, 2014)

Garyt said:


> "Best for it's time" May well be the A6M2. It was certainly superior to the Bresters, Wildcats and P40's it ran into.



From my knowledge it was only superior in certain combat situations (i.e. close quarter dog fighting). Once better tactics were in place (boom and zoom), it was basically a 1:1 kill ratio


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## Hiromachi (Mar 14, 2014)

It's not so easy to say B&Z and Zero is over. Zeros did very well over China in 1940 when they fought against more agile planes like I-152 (or I-15 bis), they did very good in 1941/1942 offensive campaigns, for example in fights for New Guinea from April 1942 to September 1942 Japanese lost 18 Zeros, 4 G4M1 and one J1N1 while Allied forces lost 41 P-39's, 5 P-40's, 10 P-400's, 2 B-17's, 3 B-26 and 4 A-24's. Yes, I know they fought elite Tainan Kokutai but still, statistically Allied fighters were faster. 

Even in 1943 they could fight the enemies, despite being outperformed by planes like F4U or P-38. In 1943 reports like the one made by Lt. Cdr. Mitsugu Kofukuda from Yokosuka Kokutai ("Research on Fighter Tactics Learned in Battle Lessons", 1943), he reported 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 ..._".
And indeed Japanese still could fight with US forces pretty well, unless they were outnumbered or simply caught by surprise. 
I can bring a couple of encounters and results :
- on April 1st 1943 in combat Japanese lost 9 planes while Americans 6
- May 13th, 1943 - Japanese lost 4 planes, Americans 5
- June 7th, 1943 - Japanese lost 9 planes and Allies also 9
- June 12th, 1943 - Japanese lost 7 planes, Allies 6
Even later, in interception actions like the one on 18th July 1943 when 56 US bombers covered by 134 fighters were trying to bomb Buin airfields, were intercepted by 40 Zero's, Half of them engaged almost 30 F4Fs (which covered SBD formation), while rest attacked B-24 formation and their escort containing P-38s and F4U's. From those combats, one TBF, six F4Fs and three F4Us failed to return while only two Zeros were shot down. 

The series of fighter vs fighter sorties which occurred in early to mid 1943 Japanese all over lost 29 Zeros while US 28 planes (from that eleven were brand new and considered as outperforming enemy, P-38s and F4U Corsairs), plus another 3 US planes were unrepairable due to combat damage.

The true problem was not a combat ratio, but fatality ratio among pilots, for 3 Japanese pilots only 1 American was killed which simply led to deterioration of Units. Especially when we consider that US Units could be replaced by others due to very effective rotation system, while Japanese unable to train so quickly pilots had to fight till the end.

But once again, I would not be so quick on saying B&Z can cure everything. It didn't work so easily earlier and later, Japanese still could fight 1:1. When I read the memoirs of pilots who fought at that time (1942-early 1944) they had a high respect toward enemy and knew that they are fighting dangerous enemy. After all even Pappy Boyington was shot down in his Corsair ... 

Sources:
- Richard L. Dunn - "Exploding fuel tanks. Saga of technology that changed the course of the Pacific air war"
- D. Wagner, May 1942 - “Report on first action against Japanese by P-39 type airplane”

Anyway, I hope my small input wont be taken negatively, I only wanted to add something.

And about the best Japanese fighter ... I am not sure what to say. What fighter ? What time ? 
For the escort purposes the A6M2 Zeros wins every time due to exceptional range.

For interceptions ... Ki-44-II Shoki and J2M3 Raiden look "tasty", also if working properly, the Ki-84 was a dangerous opponent. 

For overall performance with easiness of handling and good dive performance - Ki-100.

Hiromachi

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## Thorlifter (Mar 14, 2014)

I understand your point completely and thank you for the statistics above. And please don't take my point that the zero was an easy kill. I never said B&Z cured everything. I simply meant that with better tactics the Zero's dominance wasn't so great. Somewhere on this forum are statistics showing that once better tactics were put in place, allied fighters fared much better against the Zero. I'd point to it but I can never find anything.

And your statistics show my point exactly. I said with better tactics it was basically 1:1. The four dates you show is 29 to 27 and your mid 1943 reference is 29 to 28. That's basically 1:1.

You have an excellent point in the allied planes protected the pilots better and had a much better survivability over the Japanese planes, which were more prone to catching fire. More experience pilots could be returned to duty while the experienced Japanese pilots had a much higher morality rate when shot down.


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## CobberKane (Mar 14, 2014)

Thorlifter said:


> From my knowledge it was only superior in certain combat situations (i.e. close quarter dog fighting). Once better tactics were in place (boom and zoom), it was basically a 1:1 kill ratio



It could equally be said that the adoption of B Z tactics by early war allied fighters was effectively confirmation of the Zero's overall superiority. The only way a P-40 or Wildcat could reliably best a Zero one on one was by attacking with a height advantage to negate the Zero's performance advantage and doing a runner if that didn't work. Tactics and training gave the US pilots parity, but there was nothing inherent in the fighters they were flying that made things like the Thach Weave effective. Different story with later war fighters, of course. I don't think too many P-51 pilots would have hesitated to take on a Zero one one one at at equal altitude, even given the Japanese aircraft's advantages in climb and turn.


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## Hiromachi (Mar 14, 2014)

> You have an excellent point in the allied planes protected the pilots better and had a much better survivability over the Japanese planes, which were more prone to catching fire. More experience pilots could be returned to duty while the experienced Japanese pilots had a much higher morality rate when shot down.



Actually the book I based on ("Exploding fuel tanks") signals that, but not as much. The fuel tanks could not protect against 20 mm cannons, which were mostly the reason why F4U's were shot down. The protection of fuel tanks rather allowed pilot to have more time to bail out - as time between hits into main fuel tanks in Zeros and explosion was usually short, while in F4U pilot with his back protected from any bullets, and protected fuel tanks could safer leave the plane.

The part of the problem was also that in 1942/1943 a lot of actions took place near US bases (vide Guadalcanal) so shot down pilots could be rescued, while for Japanese any action from Rabaul would be a suicide. Also ability to return often granted to strength of US planes is a little bit exaggerated while it is way easier to land with damaged plane when you have 10-30 miles (or generally closer to Henderson Field) than you have to continue flight in damaged machine way back to Rabaul.


I very much enjoyed a book, because Mr. Dunn marked a lot of things which usually are avoided in discussions, like the range to bases, good rescue system, etc. 

Japanese in this "areas" were in a disadvantage. 



> P-40


Not so much, at least New Guinea and Australia battle theaters shown that Zeros had an advantage.



> Wildcat


Actually I found it very interesting that way slower and worse climbing F4F had better combat effectiveness than P-40 or P-39, I suspect a lot of that depended on better Navy training. But eventually such comments raised :



> A report summarizing the combat performance of the P-400 and F4F-4 against the Zero over Guadalcanal in late September 1942 stated: “At all altitudes under 10,000 feet the P-400's can pull away from the Zero (P-400 speed about 360 m.p.h. F4F-4 about 40 m.p.h. slower). Zeros are faster than the F4F-4's at all altitudes and more maneuverable…” (Performance).
> In a report based on questioning forty fighter pilots of VMF-121, 212 and 251 and VF-71 concerning combats in October 1942 the discussion of comparative performance was brief: “A Zero is faster, more maneuverable, and has a higher rate of climb than our F4F-4s” (Observations).
> In an after action interview given in November 1942 Major John Smith, commander of VMF-223 at Guadalcanal , said little about the Zero's performance until asked a direct question and then replied: “They had much more performance than we had. I think they did because we just couldn't stay with them at all, and dog fight at any altitude.”
> The F4F-4s of VF-5 commanded by Lt. Commander LeRoy Simpler flew against Zeros from a carrier in August 1942 and were land based on Guadalcanal during September and October 1942. Upon returning to the U.S. Simpler was apprised of the test report that said an F4F-4 was equal in speed to a Zero at low level. His comment was that the report was “flat wrong.”
> ...


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## parsifal (Mar 14, 2014)

Thorlifter said:


> From my knowledge it was only superior in certain combat situations (i.e. close quarter dog fighting). Once better tactics were in place (boom and zoom), it was basically a 1:1 kill ratio



Nope. Zeroes lost in air combat for the whole of 1942 amounted to about 156, according to joe B, and he would know. Others were lost on the ground or on the deck, or simply wore out. In that time they shot down at least 800 aircraft that i know of. The only aircraft that came close to a 1:1 exchange rate in the first half of the war was the F4F 

The revised tactics against the Zeke were adopted at the end of October 1942. Admittedly loss rates improved markedly in favour of the US, but Zeke loss rates remained quite low, and the exchange rate was well below 1:1 until the middle of 1943. 

The major factors affecting the exchange rate were a combination of factors, including increasingly long odds numbers wise, improving pilot skills for the allies, decreasing pilot skill for the japanese and increasing quality of the Allied mounts. The Japanese laboured under faulty strategic plans and a hopeless logistic support system. 

As the war drew to a close the americans were able to move around the TO with massive sledgehammer sized forces to basically crack open the various walnuts that were the Japanese island outposts. In these battles, the losses did become one sided, but not just against the Zeke. Zekes suffered no worse a loss rate than even the very latest Japanese types. when you are outnumbered in a given scrap 20 or 60:1 it doesnt matter a jot how good or bad your mount is, you are going to lose that battle, and badly.

Zekes were a competitive aircraft until the end, but the conditions they laboured under (poor pilots, numbers, logisitcs and poor operational usage) made their lives very difficult.


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## Garyt (Mar 14, 2014)

Another thing that hurt the Zeke and had nothing to do with it's performance was far better radar by the US. The US planes often had time to be where they wanted in a confrontation. Midway illustrates this in a way, namely that the Zekes were unable to deal with all groups of attacking planes and were pretty well suprised and caught out of position by the Dauntless flights. And of course this same advantage holds true in a fighter vs fighter situation.

Japanese radios were of course a problem as well, inferior airborne radio communication and inferior radar was a problem for the Japanese through the whole war. I think in general Japanese radio technology was OK for land based and ships, but they were nowhere near as advanced as the US when it came to minimizing the size of these components.


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## Thorlifter (Mar 14, 2014)

CobberKane said:


> It could equally be said that the adoption of B Z tactics by early war allied fighters was effectively confirmation of the Zero's overall superiority. The only way a P-40 or Wildcat could reliably best a Zero one on one was by attacking with a height advantage to negate the Zero's performance advantage and doing a runner if that didn't work. Tactics and training gave the US pilots parity, but there was nothing inherent in the fighters they were flying that made things like the Thach Weave effective. Different story with later war fighters, of course. I don't think too many P-51 pilots would have hesitated to take on a Zero one one one at at equal altitude, even given the Japanese aircraft's advantages in climb and turn.



Very true. That's what I'm saying. Better tactics gave the allies plane their advantage so they didn't have to take the Zero on in a good old dog fight. If you are in a boxing fight against a boxer with a good jab, you are not going to stand in front of him. You will adopt better tactics to avoid where you know you can be beat. I don't care what plane you were in and it's August 1st, 1945. It would be dumb to get in a dog fight with a Zero.


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## Hiromachi (Mar 14, 2014)

> Another thing that hurt the Zeke and had nothing to do with it's performance was far better radar by the US. The US planes often had time to be where they wanted in a confrontation. Midway illustrates this in a way, namely that the Zekes were unable to deal with all groups of attacking planes and were pretty well suprised and caught out of position by the Dauntless flights. And of course this same advantage holds true in a fighter vs fighter situation.
> 
> Japanese radios were of course a problem as well, inferior airborne radio communication and inferior radar was a problem for the Japanese through the whole war. I think in general Japanese radio technology was OK for land based and ships, but they were nowhere near as advanced as the US when it came to minimizing the size of these components.



Radar was a key to many achievements, as allowed to guide towards unsuspecting anything planes. 

And Midway is not best example, even if Japanese would have a radar it wouldn't help much. There was simply not enough Zeros to take down all groups, TBD Devastators were massacred but to climb again and engage dive bombers there was no time. And ammo. Big disadvantage of A6M2 was amount of 20 mm shells, only 60 per gun. Pilots very often complained on that. 


About radios, it is also not one sided stuff. Japanese radios were not horrible, they just had one frequency as the main doctrine of radio silence didn't require more than that. A lot of times radios were removed not only due to quality, but also weight and that they were not used in combat. And it also has to be separated, as Navy and Army used different equipment.

Generally it is said that from 1943 the quality of radios used in Japanese planes improved by far from what was found in early models.


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## Totalize (Mar 14, 2014)

Regarding the Zero.

I read somewhere the Saburo Sakai really hated it at first when his unit was issued the new airplane. He didn't like the cannons, had too little ammo and the muzzle velocity was poor, though damage was great once they hit home. He didn't like the canopy either. Found it too encumbering. Also, loading the ammo was a massive pain in the a$$ as the ammmo had to be loaded into a drum then loaded into the aircraft. It was not belt fed (A6M2 originally, changed to belt fed with the A6M5). One guy had to bend over while the drum was loaded onto his back then he had to raise himself up to allow the loader to put it into the aircraft. Sakai says many times this was so exhausting that he wanted collapse afterward.


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## razor1uk (Mar 14, 2014)

It is generally thought of that Airforces have maintenance personnel as a seperate group to the piltos and flying crews, as fair as my reading about both the IJA IJN so far, IMHuO, the pilots and aircrews were trained to understand their aircraft and to do the maintenance work themselves when needed, say for when forward deployed to remote areas, where skilled maintainers were few in comparison to the number flying men, hence explaining Sakai's statement about re-arming being exhausting.

I wonder if other people have seen/read/noticed similar thoughts to that?


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## Garyt (Mar 14, 2014)

"And Midway is not best example, even if Japanese would have a radar it wouldn't help much. There was simply not enough Zeros to take down all groups, TBD Devastators were massacred but to climb again and engage dive bombers there was no time. And ammo. Big disadvantage of A6M2 was amount of 20 mm shells, only 60 per gun."

There were about 30 Zeroes which flew CAP that morning, not all at on time though.

There were about 40 torpedo planes that attacked - but given enough warning from radar they would not have had all 30 chasing torpedo planes at low level. Probably would have split the attack, leaving about 15 for each. And you don't need near a 1:1 ration of fighter to bombers to disrupt the attack.

The CAP does not need to shoot down every bomber to be successful (though the Japanese came close to doing this with the torpedo bombers). Would this different deployment of the CAP stopped all bombs/torpedoes from striking home? Probably not. But it would have probably meant 1-2 carriers lost, not 3.

"About radios, it is also not one sided stuff. Japanese radios were not horrible, they just had one frequency as the main doctrine of radio silence didn't require more than that. A lot of times radios were removed not only due to quality, but also weight and that they were not used in combat. And it also has to be separated, as Navy and Army used different equipment "

Whether they were removed due to weight, inefficiency or doctrine is largely irrelevant. Point is they were not able to conduct radio communications as effectively as the US. And lack of radio communication would have made the proper vectoring of CAP very difficult, negating somewhat early warning radar even if available.

Yeah, Japanese radar and radios got better later in the war, but the strong US advantage in these 2 areas hurt the A6M2's ability to be as effective as it could have been.

By 1943 when Japan starts to get better radar and radios (though still behind the US technologically in these areas), the A6M2 no longer held a qualitative advantage to US fighters, as the 2nd generation of American fighters were beginning to see action.


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## cherry blossom (May 20, 2014)

CORSNING said:


> jim, The horse power listed in the TAIC reports was for a perfectly working engine. That was something not all Japanese A/C had in late 1944-1945. The power levels listed were not exact what was actually out in the field. The Ki.84's figures are for a 2,050 hp. A/C. From the information I have read, some in the field Franks were barely cranking out 1,800 hp.
> 
> ...snip...



I found another view of the mystery of the Homare power at J-Aircraft F6F-5 Hellcat the Ki-100/ N1K2-J Shiden-kai where Wells posted:

Hiromachi provided some useful information from an official manual of the prototype Shiden-kai, which stated that Kawanishi had calculated a speed of 348 knots at 6000 m, but that the airplane only performed to 330 knots at the same height. This was because the Homare 21 engine was supposed to make 1700 HP, using +350 mm of boost at 3000 RPM but was de-rated to +250 mm and 2900 rpm. This is the same thing the US manuals say, when using 91 octane, instead of 100 octane fuel. You have to use a lower manifold pressure.

Thus at least some people are arguing that the Homare was designed for 100 octane fuel and could thus give more power if 100 octane fuel was available.


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## tomo pauk (May 20, 2014)

The Homare was using water injection in order to circumvent the fuel limitations. The report, kindly posted by krieghund in the 'Engines' sub section, gives ~1650 HP power when water injection was used in second superchager gear.
Question also arises: why the max RPM was lowered from 3000 to 2900? Fuel should not be the issue, maybe it's about reliabilty?

It is very much possible that earlier Homare versions did not used water injection.


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## Shortround6 (May 20, 2014)

Just a guess but it might be related to cooling. Air cooled engines having a bit of problem at high altitudes for several reasons. Not only do you have less air flowing over the cylinders but the supercharger in high gear heats the air to a higher temperature than in low gear even though the intake air is cooler. Limiting the engine rpm not only reduces the power output and heat generated but lowers the supercharger impeller rpm by somewhere around 900-1000 rpm for most engines in high gear and trades heat/destiny of the intake charge against the extra power of the rpm. Might be important depending on the limit of the fuel. I would also note that the P&W R-1830 often was restricted to 2550 rpm in high gear vs 2700 rpm in lower gears for military power or while military power was listed for low gear it was NOT listed for high gear ( or for high gear on the two stage engines).


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## Glider (May 20, 2014)

The Japanese did have radar at Midway but it was only fitted to a couple of the BB's which were not with the carriers. If they had been who knows what would have happened


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## Sir Percy Ware-Armitage (Mar 29, 2017)

Great comments! As far as I know, the following problems affected the Japanese fighter planes from late 1942: first of all, experienced pilots couldn't be replaced after he battle of Midway (green rookies were ill prepared to face a much larger American opposition with competent training); also as the war progressed, Japan had serious difficulties with its engine production (i.e. the Ki series engine gremlins) as well as the bombing impediments of course. It appears (in my humble opinion) that the engines produced at most times always lacked the comparative h.p. of their American contemporaries.


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## Robert Porter (Mar 29, 2017)

Something I have never fully understood the causes for. I have read over and over that the shortage of pilots was a huge issue in Japan. Was there such a small supply? Was it cultural? I mean pilot training must have been similar the world over and the RAF and USA seemed to make good on staggering losses of trained men why did not the Japanese?

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## Sir Percy Ware-Armitage (Mar 29, 2017)

Robert Porter said:


> Something I have never fully understood the causes for. I have read over and over that the shortage of pilots was a huge issue in Japan. Was there such a small supply? Was it cultural? I mean pilot training must have been similar the world over and the RAF and USA seemed to make good on staggering losses of trained men why did not the Japanese?




It seems that Japan's pre-war training demanded exceptional qualities from its applicants (reference: Saburo Sakai) which also explained Japan's early war dominance of the skies (in association with the Mitsubishi fighter outstanding qualities). I suspect that after the great pilot loses of 1942, the navy and the army never had the quality/experienced pilots required to an efficient training program (in fact an acute problem with the numerical US dominance therefore pilots like Sakai and others remained on the front line), as well as the facilities (due to bombing) and possibly the need for an effective fast paced and quality curriculum. In many ways, the Germans faced an identical problem on both European fronts plus in both cases, an acute material unbalanced meant in some cases that an allied inferior product would upset its opponents through sheer quantity (an example from another field: Sherman tanks could by their sheer numbers overpower the superior hardware facing them).

The RAF and the USAAF: had a crucial advantage - security. Pilots could be trained across the Atlantic or the Pacific) without interference. Planes of all types could be produced without bombing handicaps which postponed production or simply destroyed the facilities. It became an extremely potent interference in all cases for the axis powers.

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## Elmas (Mar 29, 2017)

German and Japanese aircraft production was stretched to the limit and completely dedicated to the production of fighter planes and bombers and their industrial system could not afford, for example, the sixteen thousand North American T6 produced, not to mention all other basic and multi-engine trainers produced in U:SA:, U.K. and Commonwealth and U.S.S.R.
After September 8th, 1943, Luftwaffe was delighted not only to get all valuable Italian aircrafts present in some numbers, like the SM 82 transports, but also to all Italian trainers on which Luftwaffe could lay their hands.
If you add to this a chronic shortage of gasoline allowed to the flying schools the picture is almost complete.


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