Kawasaki Ki-100

Perhaps I have not seen the best references on the Kawasaki Ki-100 fighter, but from I have read, its performance parameters don't seem particularly impressive. Its maximum speed (360-380 mph) is low by 1944-1945 standards and it doesn't perform well at high altitude. Yet almost universally the Ki-100 is described as one of the best, if not the best, Japanese Army Air Force fighters. Some even say it surpassed the Nakajima Ki-84 fighter, whose performance specifications seem to surpass the Ki-100. Is the reputation of the Ki-100 warranted and why?

Thanks,
PG

They did build 3 x Ki-100-II prototypes that were equiped with a turbocharger that significantly improved it's high altitude performance. That version I think would have been excellent.

paradoxguy said:

Perhaps I have not seen the best references on the Kawasaki Ki-100 fighter, but from I have read, its performance parameters don't seem particularly impressive. Its maximum speed (360-380 mph) is low by 1944-1945 standards and it doesn't perform well at high altitude. Yet almost universally the Ki-100 is described as one of the best, if not the best, Japanese Army Air Force fighters. Some even say it surpassed the Nakajima Ki-84 fighter, whose performance specifications seem to surpass the Ki-100. Is the reputation of the Ki-100 warranted and why?

Thanks,
PG

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The KI-100 was converted from the KI-61 using design techniques taken from the Fw190, but was about 725 pounds lighter because it had a radial. The only thing that was considered negative about this machine (KI-100 Ko Otsu) was it's overall speed in level flight. However, it was capable of keeping up with a P-51D in a dive, a good turning fighter, a decent climber and it's firepower and max altitude (36,090 feet) capability made it dangerous to the B-29s.

There were less than 400 made by war's end, so this aircraft was never able to reach it's full potential as a main line fighter.

There is a controversy re. real speed of Japanese planes. The Hayate's speed is most of the times found to be 630km/h (under 400mph), yet the US tests claim it was capable making 680km/h. Quite the difference.
Perhaps speed of the the Ki-100 was not 590km/h as the on-line sources claim it, but greater.

It may be that its reputation was based on relief - relief for the Japanese that they had an aircraft that was reliable, and was something that would not be outclassed compared with others they were left with.

Although the ki-61 was a good robust aircraft - the engine was unreliable, and supplies of new engines dried up. With Ki-61 airframes left unused - the search was on for a reliable available engine. The solution lay in the Ha-112-II 14-cyl dbl-row radial. The trouble was this engine had a diameter of 1.22 m (4 ft), compared with the 0.84 m width of the fighter fuselage - this is where the example of the Fw 190A came in handy.
All the spare Ki-61 airframes were used with the new engine, plus more built from scratch as Ki-100.

It may not have been as good as the Allied aircraft, of the time, but it would have been a surprise nonetheless - to see an apparently totally new aircraft arrive on the scene. And when its 'new' the uncertainty factor could creep in - is it any good. Whereas for the Japanese, well it may not have been great - but the pilots might have felt they had more of a chance than with the unreliable Ki-61 or even Ki-43!

I agree with Merlin
the main asset for Ki-100 vs Ki-84 was reliablity of its engine and landing gear. Homare of Ki-84 was temperamentical and often didb't give the power it should and engine of Ki-100 was reliable and delivered what was expexted.

Juha

Maj Y Hinoki, high claiming JAAF pilot wounded twice in 42-43, who flew Type 5 fighters (ki-100) late in the war described the plane as not completely debugged, this is as of July '45. The plane was first used in March, but apparently not much. Its whole fighting career was pretty limited, and the image of it as formidable element probably comes in part from older western books (Green, Francillon) that may have overhyped it.

In two, two side documented combats involving Type 5's I know of, 244th Sentai downed 2 F6F's of VF-31 for 2 Type 5's lost July 25 (their claims were 12:2, often misstated as 14:0), and Hinoki's Akeno Fighter school unit lost 5 Type 5's and 3 pilots on a day where 7th AF lost 1 P-51 in air combat July 16; and the 244th lost a pilot in a Type 5 in combat with P-51's that day too, possibly other a/c.

I agree as was stated, the speeds of late war Japanese fighters are still obscure. Some of the very high numbers appear to have been calculated estimates (oh no, the trouble we sometimes have on this forum, quoting calculated estimated graphs as facts! ) not actual test results on captured planes. This appears to be the case of 427mph quoted a Type 4's best speed, often quoted as a postwar trial result, but coincidentally or not the same speed appears in a manual about Japanese a/c published during the war before any Type 4's had been tested. AFAIK there are no higher estimates or trial results for the Type 5, but the real speed should still probably be viewed as uncertain, IMO.

Joe

JoeB said:

I agree as was stated, the speeds of late war Japanese fighters are still obscure. Some of the very high numbers appear to have been calculated estimates (oh no, the trouble we sometimes have on this forum, quoting calculated estimated graphs as facts! ) not actual test results on captured planes. This appears to be the case of 427mph quoted a Type 4's best speed, often quoted as a postwar trial result, but coincidentally or not the same speed appears in a manual about Japanese a/c published during the war before any Type 4's had been tested. AFAIK there are no higher estimates or trial results for the Type 5, but the real speed should still probably be viewed as uncertain, IMO.

Joe

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The manual it's that with march 1945 as date? so it's after the capture of Ki-84s at Clark field so maybe that S10 and S17 were not tested but it's not 100% sure. S10 crashed within test, i'm not sure but i think at Clark field. S17 also flew and after was tested also in '46. but performance was not know. There is a british report that give 400 mph at 20k' (it's test of one of Ki-84 of Clark field, the plane have trouble with CSU of engine)

Vincenzo said:

The manual it's that with march 1945 as date? so it's after the capture of Ki-84s at Clark field so maybe that S10 and S17 were not tested but it's not 100% sure. S10 crashed within test, i'm not sure but i think at Clark field. S17 also flew and after was tested also in '46. but performance was not know. There is a british report that give 400 mph at 20k' (it's test of one of Ki-84 of Clark field, the plane have trouble with CSU of engine)

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Yes TAIC manual dated March 1945, but the introduction says all figures therein were estimates unless otherwise noted, and it's not otherwise noted. The British document refers to a real test, but 400 and 427 aren't really the same .

Some people have a mentality that we'll get down to the one true value (often to program that into our sim game, how can you have a uncertain value in a sim game? that's probably annoying to most gamers). IMO it's simply not known what the speed of Type 4's was with any precision, especially considering Type 4's in actual Japanese Army operating conditions, IOW the only case that really mattered much.

Joe

in actual Japanese Army operating conditions

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From the little I've read of Wright-Patterson comparative performance tests postwar of various types this was given as a major issue of consideration for late war Japanese fighters. I remember reading the Ki-84 was more highly regarded by test pilots at Wright-Patterson than the Japanese themselves, but that it was due to better maintenance and operating conditions which were not exercised during the war for circumstance.

Interestingly flight testing of the Fw-190D returned nowhere near the level of admiration that it received from Luftwaffe pilots. It was stated by American test pilots as pretty rough particularly in terms of overall finish, with heavy handling, but considering the circumstances again, was certainly competitive with late war Allied types and that much was impressive at least. IIRC the overall impressions were of a backyard hack with surprising performance for a backyard hack, where the test pilots had expected something far more refined.
Everybody who few a Ta-152 was pretty impressed though, except the Focke Wulf test pilots who found it fell short of calculated expectations at extreme altitude, plus any aircraft of this era experienced a wide variety of technical difficulties operating at such altitudes in the first place. But very, very strong from 7000 metres to excess of 10500 metres, and not altogether a slouch at lower altitudes either.


Definitely I also have a distaste for presenting calculated figures as any reflection of actual flying characteristics whatsoever. The opposite should be strenuated.

vanir said:

Definitely I also have a distaste for presenting calculated figures as any reflection of actual flying characteristics whatsoever. The opposite should be strenuated.

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A-Fricken-Men!

JoeB said:

Yes TAIC manual dated March 1945, but the introduction says all figures therein were estimates unless otherwise noted, and it's not otherwise noted. The British document refers to a real test, but 400 and 427 aren't really the same .

Some people have a mentality that we'll get down to the one true value (often to program that into our sim game, how can you have a uncertain value in a sim game? that's probably annoying to most gamers). IMO it's simply not known what the speed of Type 4's was with any precision, especially considering Type 4's in actual Japanese Army operating conditions, IOW the only case that really mattered much.

Joe

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400 are not 427 but the power setting of engine was not the max.

The Type 4 was ~1.3 tons lighter of Corsair, the corsair in military (fth) had 1650 hp and run near over 400 mph, the frank had ~ same power at him FTH so is not strange that can run faster, also if is not compulsory.

For many people the war is not over, so for him country was best of enemy country.

I think it is also important to note that an aircraft that can do 390mph at 10,000 feet is faster than an aircraft that can do 400mph at 15,000 feet in most combat encounters.

By that I mean when comparing one fighter type to another you cannot say this is better than that even in the sense of calculated figures and data under test conditions, unless you have extremely detailed results of actual flight testing at all altitude steps and projected engine and supercharger efficiency specifications, take into account fuel quality and production synthesis, field maintenance routines and performance conditions...

It's too easy to say, "This book in the library says the Corsair does 415mph and the Ki84 does 390mph so the Corsair is clearly faster," when this statement is completely ridiculous for just so many reasons it's worth a full publication to list and explain them. The easiest and quickest counter is a simple combat record, where US fighters based on Okinawa reported they were simply unable to catch a flight of Ki84 at medium altitude. But if that turns into a quid pro quo then such a publication perhaps might be a good idea.

It helps to have more detailed reports too. Did the Corsairs start out 1 mile behind the Ki 84s or 15 miles behind ( vectored in by ground radar?) . Did they start 5000 ft above or 5000ft below? Did they start with nearly full tanks or had they been in the air several hours and didn't have the fuel for a long chase?

I am not making excuses for the Corsair here. Just pointing out that without more details a SINGLE combat report doesn't really tell us much.

I do agree with you though, that too many peaple take the speed figures from a book while ignoring the altitude difference.

Counter example would combat between 35th FS P-38L's and 47th Sentai Type 4's Aug 14 1945. One victory was claimed against a Type 4 running away at 3k ft. The P-38 chasing was able to overhaul it and down it, which according to the highest estimates (real trials results?) of Type 4's it would not have been able to. And AFAIK the comment about F4U and Type 4 was in fact in context of intercepting Type 4's acting as fighter bombers, where intruding hit and run high speed bomber doesn't have to be actually faster than the interceptors to make interception impractical. That's not the same as being slower in a race with same starting condition (though that may also have been true in certain circumstances).

Also on Type 4 v Seafire trial (that one was a real trial), 400mph and not 'full power', a lot of these uncertainties are a matter of what 'full power' really was. Less than 'full power' in terms of the maximum Allied evaluation personnel squeezed out of a captured plane might still be higher boost condition that it reached in actual service in Japanese air arms. It's clear that the official Japanese sub 400 speed of the Type 4 was at lower boost, though also perhaps lower than the plane was capable of even in service conditions. The speed capability in actual combats with Allied fighters will simply never be certain IMO, and that's the speed that mattered most. And same goes for the Type 5.

Joe

What japanese docs talking of trouble with boost?
For british trial is not only a boost difference there is a difference also in rpm (british trial 2900 rpm 250 mm Hg, engine specs 3000 rpm 350 mm Hg (the boost can up until 500 for take off, idk also if for wep or injection)

Vincenzo said:

What japanese docs talking of trouble with boost?
For british trial is not only a boost difference there is a difference also in rpm (british trial 2900 rpm 250 mm Hg, engine specs 3000 rpm 350 mm Hg (the boost can up until 500 for take off, idk also if for wep or injection)

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It's not 'trouble' it's just difference. The Japanese had no such thing as WEP, for example. Engine specs according to who? I don't know the exact specs but it's a fact the Japanese official best speed for that plane was less than 400. I mean that's the whole discrepancy we're discussing. If the Japanese had posted an official speed equal to the highest in Western trials or estimates, we wouldn't be discussing it right? Aren't you missing something basic here, or am I?

Joe

JoeB said:

It's not 'trouble' it's just difference. The Japanese had no such thing as WEP, for example. Engine specs according to who? I don't know the exact specs but it's a fact the Japanese official best speed for that plane was less than 400. I mean that's the whole discrepancy we're discussing. If the Japanese had posted an official speed equal to the highest in Western trials or estimates, we wouldn't be discussing it right? Aren't you missing something basic here, or am I?

Joe

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nakajima book.
it's knew japanese data was for plane with homare-11 engine. japanese have not wep terminology sure, all other don't use wep word, but like climb and combat setting for british or combat and take off setting for germans.

In some cases the American WEP was just, WAR ENERGENCY POWER. it was not to be used for take off, or climb or for ANY REASON out side of a combat zone. Any use of combat power was to be noted in the log book as more frequint maintainece would be required after a certain amount of time at WEP. In many cases small wire "tell-tales" were place across the throttles that had to be broken in order use the WEP settings.
Other countries may or may not have had similar restrictions on max power settings but if they didn't then the power settings are not strictly comparable.

American engine settings aren't strictly comparable to European or Asian anyway. Theirs were NACA developed during the thirties for the purpose of increasing the normal range of combat aircraft. The normal cruise setting for American fighters is the economy setting for European types, the WEP is often not even listed in operational guidelines and there is a separate 5-10 minute take off setting (WEP is a 5min setting). Climb and combat is still the 30 min setting, but max continuous is also the cruise setting in Europe, whilst in the US it is stated in operational guidelines this setting will not return the listed normal cruise range.
Effectively it bumps the normal cruise range of US fighters on paper, though its purpose was to culture pilots to use lower cruise settings during normal flight. The effect is that a European pilot will get much less range out of an American fighter if he flies it like a European fighter (which may be more appropriate in a European combat environment).
American WEP settings are also a bit of hack and slash. For the F-series Allison it was given by the company as 52" and later increased to 56" although 60" was unofficially sanctioned and recalibrations and engine overspeeding were performed in the field "for extended periods"

Therefore for engine comparisons the International Rating became the standard at this time rather than maximum listed output, which varied by doctrine as well as engine type. It is the 30 minute setting, regardless of where the engine was made and how many take off and WEP settings and grades it has.
For warbirds there is a mixture of maximum claimed outputs and International ratings given for various aircraft, which does rather confuse things tremendously.

For the P-40 series for example, the International rating is invariably given in warbird publication. Actual take off performance is more like 1350hp and up with a WEP of 1550hp and up. Totally changes the perspective of this type's low altitude performance (very, very tough under 10K ft in any role).

For the Spitfire you'll have maximum take-off/WEP (+18lbs or 66"Hg for 5-10min, Merlin XX onwards) ratings given at optimal altitude (about 3100ft).

So two aircraft which perform very similarly under 5000ft are stuck with published figures of ca.1050hp and 1550hp respectively for comparison. No wonder everybody underrates the P-40 and overrates the Spit.

Happy to be corrected on any points, I'm not that much of an expert.