Ki-84 Hayate ("Frank")

[Ol Paint]

Let me get this straight.  You admit the the Frank could out turn & out climb any operational US fighter at the time but still say that claims that it is superior are BS.

 

I agree that there are a lot of factors that go into a good fighter & that comparing fighters in only one (or a few) of these factors & claiming one is superior to the other is folly.

 

The Frank was easy to fly & an good gun platform.

 

Many claim that the lower top speed of the Frank compared with US fighters as an argument against its superiority but a plane's operational top speed is misleading as it is only indicates the plane's top speed at one specific altitude & the only "official" top speed rating we have for the Frank is that of 388mph for the original (1800hp) prototype.  The production Frank was supposedly faster than US fighters a low to medium altitudes & it was only at higher altitudes where US fighters could reliably outrun it.

 

While searching the internet on the Frank, I came across the following webpage:

 

http://www.csd.uwo.ca/~pettypi/elevon/baug...ther/ki-84.html

 

Admittedly one should take anything found on the internet with a grain of salt but the references for the article look legit to me & there is nothing said in the article that I have not read elsewhere before.

 

The relevant passages are:

So it seems obvious that a well maintained Frank with a good pilot was more than a match for any US fighter at the time (at least at low to medium altitudes - higher altitudes may be somewhat debatable however). 

 

With that being said the combination of a good Japaneses pilot & well maintained Japanese aircraft was hard to come buy during 1945.

226705[/snapback]

 

No, because you also have to specify US fuel, which had considerably higher octane ratings than Japanese fuel, late in the war.

 

And, if you are going to compare late-model Ki-84 to American fighters, the P-47D isn't the example to compare with. The P-47N, a contemporary of the "late-production" Ki-84 was clocking 397mph @ 10,000ft, 448mph @ 25,000ft, & 460mph @ 30,000ft. By linear interpolation, the P-47N is good for 431mph @ 20,000ft. The F4U-1 was capable of 417mph at 19,900ft, but the F4U-4 was at 441mph @ 26,200ft, which is contemporary with "late-production" Franks. Applying the same linear interpolation model to the F4U-4 (since I only have one data point, I assumed the same slope to the line and adjusted for the difference in airspeed), I get 419mph for the F4U-4, which is slightly less than the Ki-84, but probably more indicative of wartime performance than 427mph is for the Ki-84. In addition, the Ki-84 had a service ceiling of 34,450ft, compared with 40,000+ for the P-47N, 41,500' for the F4U-4, and 41,800ft for the P-51D. So the US fighters have the ability to operate higher, have equal speed (or better), lower steady rate of climb, less maneuverability, better fuel (which translates into lower speed and climb numbers for the Ki-84 in service), and probably better quality control for more similar performance fleet-wide. The Ki-84 appears to be, at best, an equal but is more likely to have had inferior performance in many areas due to the inability to acquire US 100/130 & 100/150 octane fuels. And these comparisons probably do not do the US fighters justice since the Ki-84 is equipped with a single-stage supercharger vs. turbo-charging (P-38/P-47) or two-stage supercharging (F4U, F6F, et al.), which is going to give a much wider performance envelope to the Allied fighters.

 

There is an interesting article here: http://www.clubhyper.com/reference/ki84performanceaj_1.htm The conclusion of this article is as follows:

No Japanese fighter aircraft had a better all-round performance than the Ki-84. As far as protection goes, the Ki-84 had seat back and head armour of 12 mm steel, and self-sealing fuel tanks. The self-sealing tanks were not considered as efficient as those fitted to American aircraft at the time.

 

The Ki-84 was not clearly superior to any of the Allied fighter aircraft opposing it. In perfect running order it was perhaps the equal of any allied fighter at 20,000 feet or below. A good pilot would be able to take advantage of its excellent turning, climbing and acceleration characteristics to at least give an allied opponent a hard fight.

 

However, good pilots and Ki-84 in excellent running order where in short supply for Japan between 1944 and 1945.

It is very important to note that the article is comparing the 1944 production Ki-84 with the F4U-1 (1942), F6F-3 (1943), P-38J (1943), P-51B (1943), P-47D-22 (1943), and Spitfire MkVIII (1943). Also, the P-38J performance figures are obviously mil power settings, not WEP (I am not sure about the other US fighters in the table on the website). If the Ki-84 isn't clearly superior against earlier aircraft, how can it be considered superior to its contemporaries?

 

Greg,

 

I, for one, am hoping you are bored this weekend. All of my books are in storage, so I can't even go that route.

 

Joe,

 

You raise some good points with respect to developing the calculations but, in the absence of hard test data, the calculations are better than quoting book figures because the aircraft can be baselined against a common set of assumptions (manifold pressure, altitude, WEP/non-WEP, etc.) which is, in my opinion, a much better basis for discussion of one-on-one potential than comparing book figures without correcting for varying conditions. Ultimately, of course, such comparisons are moot since the historical outcome is known.

 

The Ki-84 looks to have some advantages when comparing web-available numbers, primarily in specific horsepower & possibly wing loading, but the numbers seem to point up that aircraft like the F4U-4 (which was slightly later than the Ki-84-Ia, entering combat in early '45, as near as I can tell) still had a maximum energy advantage, being capable of 30+mph more in level flight than the Frank (this changes for the later Ki-84-II models). Hopefully, GregShaw will be bored enough to work up numbers comparing the Ki-84 models with some of its contemporaries (P-47N, F4U-4, P-51D/H).

 

Douglas

 

Partial List of References:

Octanes: http://www.absoluteastronomy.com/encyclope...p/pe/petrol.htm

F4U-4: http://home.att.net/~historyzone/F4U-4.html

F4U-4: http://aeroweb.brooklyn.cuny.edu/specs/vought/f4u-4.htm

P-47N: http://home.att.net/~jbaugher1/p47_13.html

P-51D: http://home.att.net/~jbaugher1/p51_10.html

Ki-84: http://www.csd.uwo.ca/~pettypi/elevon/baug...ther/ki-84.html

 

[Edit because I misread the section on German fuels.]

Edited September 24, 2005 by Ol Paint

[JOE BRENNAN]

In 1946, a captured late-production Hayate was restored and tested at the Middletown Air Depot in Pennsylvania. At a weight of 7490 pounds, the aircraft achieved a maximum speed of 427 mph at 20,000 feet, using war emergency power.

 

Admittedly one should take anything found on the internet with a grain of salt but the references for the article look legit to me & there is nothing said in the article that I have not read elsewhere before.

226705[/snapback]

Oooonnne more time.... the 427 was apparently a calculation not a test result. It's not a matter of trusting web sources but rather than the original published sources speaking of such a test can't be authenticated. The primary source documents actually saying that can't be found by seemingly quite a few people interested in researching the topic at that level. In contrast original documents have been found showing 427 as an air intel calc, strongly suggesting that's all it ever was. Books as well as websites can be wrong.

 

Re: Doug, you're getting way ahead of me. I didn't say to use the book figures, I simply pointed out my observation that calculations by various people cover quite a wide range, and I wonder how well they are benchmarked. Greg mentioned 440-some, guys over on j-aircraft were getting considerably less. IMO the topic is simply not fully documented, an unknown. In any case as repeatedly said, neither book figures nor calcs would necessarily represent typical operational capability, which is what's most of interest to me.

 

Here's an alternate example in an area I studied. In 1950 US intel calculated the speed of the MiG-15 as 580kts (naval context here). The Soviet official result ("pure" MiG-15 RD-45 not MiG-15bis VK-1) was 567, both at s/l. In combat with the Navy the max speed demonstrated was estimated at 535, though in more than one case F9F's (officially 500 at s/l) kept up with them in low/med alt chases. The reasons could be the wing drop of early MiG's (could become too great for pilot's strength to overcome above 520 per Soviet sources), or the usual maint, fuel, mass production QC (besides the wing assymetry) etc. There is not a single answer. If I want to understand the real F9F/MiG combats of Nov 1950 that's one thing, if I want to have a theoretical abstract "warbird" kind of discussion of F9F and MiG-15's that's something else. If I brought in long after fact enthusiast calcs of speeds that would be yet another moving part, but I'd just want to know how well benchmarked against known results such calcs were.

 

Joe

Edited September 24, 2005 by JOE BRENNAN

[Guest pfcem]

Both wartime reports & postwar flight tests (whether you believe them or not) clearly state that when a well-maintained Frank was flown by a good pilot, it could out climb, out turn, & out run any US fighter at 20,000ft or below.

 

The lack of a two-stage supercharger did severely limit high altitude power & performance.

 

A good Japanes pilot would know this & stay below 25,000ft to maintian his advantage.

 

Judge the plane on its own merit. Not degrading it because of the poor state of the Japanese Empire.

 

With that being said, if I were fighter pilot in the Pacific in 1945, I would want to be flying a F4U-4. The Frank (& perhaps the George) is the only enemy plane that can match the F4U-4's combination of speed & manueverability & then only at 20,000ft or less so I can simply climb to 30,000+ft to evade a Frank (or George) that I was unable to contend with.

Edited September 24, 2005 by pfcem

[Ol Paint]

--SNIP--

Re: Doug, you're getting way ahead of me. I didn't say to use the book figures, I simply pointed out my observation that calculations by various people cover quite a wide range, and I wonder how well they are benchmarked. Greg mentioned 440-some, guys over on j-aircraft were getting considerably less. IMO the topic is simply not fully documented, an unknown. In any case as repeatedly said, neither book figures nor calcs would necessarily represent typical operational capability, which is what's most of interest to me.

 

--SNIP--

Joe

226819[/snapback]

I agree. About the best that can be done is to take similar data points and apply the same correction factors, leveling the playing field for each comparison. In these discussions, the precise numbers are less important to the comparison than the relative values, provided the original data being used is equally accurate for all aircraft being compared. It is unlikely in the extreme that several GOTIs would apply the same assumptions independently. What we can strive for are numbers generated using one set of assumptions per discussion, while understanding that taking the individual numbers calculated as absolute guaranteed performance is risky and dependent on the fidelity of the information used to generate the calculation in the first place. I think you and I agree on this point.

 

I was certainly not saying that you felt the calculations shouldn't be done. Instead, I was emphasizing the point that calculations to the same set of assumptions (i.e. generated by the same person, or using the same methods and agreed-upon baseline data) for different aircraft types are more useful when making relative evaluations of aircraft types than pulling various non-corrected numbers from various sources. The problem is that most of us don't have the hard test data readily available so, in many cases, the calculations we accept from other posters are the best numbers we have. Of course, it shouldn't stop someone for digging for better data, or questioning the results... I admit that my wording was a bit ambiguous, but it wasn't my intent.

 

My apologies for the confusion,

 

Douglas

[JOE BRENNAN]

Both wartime reports & postwar flight tests (whether you believe them or not) clearly state that when a well-maintained Frank was flown by a good pilot, it could out climb, out turn, & out run any US fighter at 20,000ft or below.

226870[/snapback]

But I think I have good reason to doubt that that performance is a flight test result, so it's not so clear And, as I also already mentioned, wartime reports from US sources of Franks (or other late war J types) actually outperforming US types in real combat are hard to find. Any plane that could do close to 400 would be hard to intercept from a standing start by any 1945 fighter; that's also true of late war J recon planes like the Dinah-III and Myrt, but we don't say they could go 427mph. Again I mean able to pull away in a chase in fighter combat, do you know of such a case specifically?* There is a definite issue here of conventional wisdom with possible holes in it being constantly repeated till it becomes "fact".

 

Here's a reason to doubt a Frank flew 427 in an actual test in 1946. Note the date on this document; quite a coincidence, same speed and altitude w/ possible dyslexic mixup on weight (7940lbs here, 7490 in Francillon). Then this would go on to possibility this was a test of a Philippines captured example before the war ended, but it's still a problem for "result of 1946 test", and the real fact whether you believe it or not is that nobody now can show primary source evidence of any 427 test. Where "427 1946 test" was first published I don't know, but Francillon is where most people seem to get it (or other sources that got it from there), and while he's written many good books, he's pretty far from 100% reliable in a number of other cases too. If something comes down to resting on him, it's not a clear fact IMO.

 

*besides Franks having such amazing performance that 507th FG P-47N's mistook 22nd and 85th Sentai Franks for Oscars while defeating them 11:1 (real) August 13 '45, as mentioned above, 35th FS P-38L's overhauled and downed fleeing Franks at low altitude in the last 5th AF fighter combat of the war. The F6F and F4U claimed exchange ratio against Franks was 114/12 and 28/4 respectively (several of the F6F losses were to 343rd AG Georges in fact, besides other likely mis id's). When the JAAF introduced the Ki-84 in China in summer 1944, there were still a number of US P-40N units, and that was noticed. In general though there doesn't seem a clear idea from US side of a greatly upgraded J fighter threat due to the new types.

 

Joe

Edited September 24, 2005 by JOE BRENNAN

[Guest pfcem]

226905[/snapback]

 

What is it about a 8,000-8,500lb plane with 2,000hp being capable of 427hp do you find so unbelievable?

 

Plus, if the Ha-45 was rated at 1,990hp on "low octane" Japanese fuel, what was it capable of with higher octane US fuel?

 

My guess is that the reason why nobody seems to be able to confirm the actual speed the Frank obtained during US fight tests in 1946 is because it turned out to be even faster (with US fuel) then they thought it would be and did not want to admit to the public how fast it really was.

 

I think we are focusing too much on the speed capabilities. With its significantly greater hp/weight ratio, the Frank could easily out accelerate US fighters, which would negate much of any speed deficite the Frank may or may not have had. A dogfight is not a race.

 

It has already been stated many times that a well maintained Frank with a good pilot was hard to come by in 1945. My understanding is that the vast majority of Japanese pilots in 1945 could take-off & fly a plane (maybe even land) but had absolutely no combat training. The performance in combat of Japanese fighters in 1945 was limited by the ability of the pilots to fly them, not the flight capabilities of the planes themselves. Plus in 1945 the US enjoyed a decided numerical advantage in most air battles & even superior planes will eventually succumb to superior numbers.

[JOE BRENNAN]

1. What is it about a 8,000-8,500lb plane with 2,000hp being capable of 427hp do you find so unbelievable?

 

2. My guess is that the reason why nobody seems to be able to confirm the actual speed the Frank obtained during US fight tests in 1946 is because it turned out to be even faster (with US fuel) then they thought it would be and did not want to admit to the public how fast it really was.

 

3. I think we are focusing too much on the speed capabilities.  With its significantly greater hp/weight ratio, the Frank could easily out accelerate US fighters

 

4. My understanding is that the vast majority of Japanese pilots in 1945 could take-off & fly a plane (maybe even land) but had absolutely no combat training. 

 

226929[/snapback]

1. I simply find the assertion that it occurred in a test to be undocumented, documents instead pointing toward it being an intel estimate from during the war, maybe or maybe not based on examination of Ki-84's captured in the PI. This lessens the precision considerably, and calls into question whether the real answer mightn't be closer to the official Japanese numbers.

2. I'll assume you're kidding and not seriously making a ridiculous statement like that.

3. Acceleration in level flight was relatively low for all WWII fighters at the higher range of combat speeds and seldom sharply distinguished them the way thrust/weight does for supersonic fighters. Same with sustained g, a slight dive greatly increased either, so a little bit of initial altitude advantage negated a lot of level acceleration performance; it's mainly an anachronism to speak of either as important factors for piston fighter combat performance. Low power loading did tend to mean better climb, that was actually important.

4. Another repetition of conventional wisdom that needs more scrutiny than it usually gets; not without some truth but tends to be exaggerated. It might be applied to special attack (kamikaze) pilots, but not regular fighter units in general. Take for example again the units the P-47's encountered Aug 13 '45, 22nd and 85th Sentai. They had been withdrawn from China to Korea awhile before. According to their own (though probably exaggerated) claims they were reasonably successful in China, but in any case had gained experience and not been worn down to nothing, then had a period of quiet (and conversion to the Frank) before they had to face US raids on Korea from the Okinawa area just before the end of the war. It's almost certainly an exaggeration to say those pilots just knew how to take off and land.

 

To muddy the waters some more there's this Japanese book: this is postwar, the third column is the same info as the March 1945 intel book, and the last line of the table gives as source "America Army Survey" (or something like, if the Japanese translation nitpickers come out the woodwork again The first column is for Homare 11 (NK9B), Nakajima/JAAF info it says. Another pillar of throwing out 624km (388mph) is much different from Homare 21. But the middle column gives 624 for Homare 21 (NK9H) per Nakajima info alone it says. So ?? is my conclusion still in general.

 

Joe

Edited September 24, 2005 by JOE BRENNAN

[Slater]

http://www.kotfsc.com/aviation/ki-100.htm

 

Not to stray too far off the subject, but the Ki-100 was evidently an outstanding aircraft. Not sure if it was in the Frank's league, but certainly effective. Basically a radial-engined Tony, from what I gather.

[Paul F Jungnitsch]

"However, the Kawasaki concern was guided in its work by being able to study the engine mount in an imported Focke-Wulf Fw 190A, an example in which a wide radial engine had been successfully installed in an airframe with a narrow width."

 

I wonder just how many of the last radial engine fighters owe something to Kurt Tank's design.

[Guest pfcem]

Before you get yourself all in a bind, I am only comparing the F4U-1 to the Ki-84-II here because of there similar engine power. I realize that the US had the F4U-4 (with a more powerful water-injected engine) in 1945.

 

F4U-1 Corsair

Powerplant: One 2,000 hp Pratt & Whitney R-2800-8W Double Wasp 46 Liter 18 cylinder radial

Length: 33 ft 4 in

Height: 16 ft 1 in

Wingspan: 41 ft

Empty Weight: 9,000 lb

Loaded Weight: 12,000 lb

Maximum Speed: 417 mph

 

Ki-84-II Hayate Kai

Powerplant: One 1,990 hp Nakajima Ha-45 model 21 35.8 Liter 18 cylinder radial

Length: 32 feet 6 9/16 inches

Height: 11 feet 1 1/4 inches

Wingspan: 36 feet 10 7/16 inches

Empty Weight: 6,500 lb

Loaded Weight: 8,500 lb

Maximum Speed: ? 392 ? mph

 

The Ha-45's smaller displacement (35.8 vs 46 Liter) implies that it would be of smaller diameter & therefor improve aerodynamic profile.

 

 

The Frank certainly looks more aerodynamic than the Corsair.

 

So how is it that we are to accept that the F4U-1 is capable of 417mph but that it is unrealistic to accept that the smaller (32' 6" x 11' 1" x 36' 10" vs 33' 4" x 16' 1" x 41') & lighter (8,500 lbs vs 12,000 lbs) Ki-84-II may be possible of 427mph?

Edited September 25, 2005 by pfcem

[Guest pfcem]

http://www.kotfsc.com/aviation/ki-100.htm

 

Not to stray too far off the subject, but the Ki-100 was evidently an outstanding aircraft. Not sure if it was in the Frank's league, but certainly effective. Basically a radial-engined Tony, from what I gather.

226979[/snapback]

 

You are correct.

 

The proposed Ki-100-III was to have been fitted with a 2,000hp radial engine.

[JOE BRENNAN]

The Frank certainly looks more aerodynamic than the Corsair.

 

So how is it that we are to accept that the F4U-1 is capable of 417mph but that it is unrealistic to accept that the smaller (32' 6" x 11' 1" x 36' 10" vs 33' 4" x 16' 1" x 41') & lighter (8,500 lbs vs 12,000 lbs) Ki-84-II may be possible of 427mph?

226987[/snapback]

I simply noted the fact that 427 has long been presented as a test result, but probably wasn't. The book which says that, and which is often repeated, is probably wrong. Then I reviewed the fact of persistent Japanese sources sticking to the 624km/h figure. It seems a new fact for you, but I don't see why you have so much trouble accepting it and are thrashing around so about it.

 

Whereas I already said I view the Frank speed controversy to be open, I just see no reason to completely accept a US intel estimate of 427 and completely throw away a reiterated Japanese official figure of 624km/hr (~388mph) even for -Ia Homare 21 (which is what this discussion is about, not the partly wood -II). Especially to completely throw it away as representative of actual operational speed, which is what really mattered anyway. I see even less reason to completely throw away that official figure based on loose comparisons to other types: the F4U-1 was a good deal faster than the similar size F6F with the same engine too, and I don't know which of those "looked more areodynamic".

 

There's still reason to suspect the official figure conservative, mainly evidence from definite real tests of other J types that did exceed their official numbers (but not by as much). But 427 is simply a doubtful number to latch onto as "the answer" as a matter of where the documents suggest it really came from.

 

Joe

Edited September 25, 2005 by JOE BRENNAN

[Guest pfcem]

I simply noted the fact that 427 has long been presented as a test result, but probably wasn't. The book which says that, and which is often repeated, is probably wrong. Then I reviewed the fact of persistent Japanese sources sticking to the 624km/h figure. It seems a new fact for you, but I don't see why you have so much trouble accepting it and are thrashing around so about it.

 

There's still reason to suspect the official figure conservative, mainly evidence from definite real tests of other J types that did exceed their official numbers (but not by as much). But 427 is simply a doubtful number to latch onto as "the answer" as a matter of where the documents suggest it really came from.

226997[/snapback]

 

I am not debating where the 427mph figure came from. What I am saying is that number seems plausible given the Frank's specifications.

 

The only "official" figure for the Frank's speed is that the original prototype attained a top speed of 388mph with the 1,800 hp Ha-45 model 11.

 

The fourth prototype reportedly had a maximum speed of 394 mph at 21,800 feet & both the second pre-production batch of 42 Ki-84s (built between March and June of 1944) built in parallel with the first production aircraft & the first production aircraft were fitted with individual exhaust stacks, which provided some thrust augmentation, and could increase the maximum speed by some 9-10 mph.

 

That brings the top speed figure "unofficially" up to as much as 404 mph with 1800 hp model 11 engines.

 

The additional 190 hp of the later model 21 engined aircraft certainly improved on that figure.

 

 

 

Whereas I already said I view the Frank speed controversy to be open, I just see no reason to completely accept a US intel estimate of 427 and completely throw away a reiterated Japanese official figure of 624km/hr (~388mph) even for -Ia Homare 21 (which is what this discussion is about, not the partly wood -II). Especially to completely throw it away as representative of actual operational speed, which is what really mattered anyway.

226997[/snapback]

 

Read the original post again. It makes no mention of which version of the Frank.

 

The Ki-84-II or Hayate Kai was an attempt to conserve valuable supplies of aluminum by employing large numbers of wooden components in the manufacture of the Hayate.

 

The designation Ki-84-II was actually a Nakajima designation, the aircraft in JAAF service retaining the Ki-84-Ib or -Ic designation, depending on armament.

 

The "all metal" Ki-84-Ib or -Ic Franks were actually about 500 lbs lighter & therefore slightly faster than the Ki-84-II.

 

I simply used the Ki-84-II for my comparison to avoid any confusion between the Ki-84-Ib or -Ic (the only difference between the -Ib & -Ic being in armement).

 

 

 

I see even less reason to completely throw away that official figure based on loose comparisons to other types: the F4U-1 was a good deal faster than the similar size F6F with the same engine too, and I don't know which of those "looked more areodynamic".

226997[/snapback]

 

The Corsair was faster than the Hellcat due to its slightly lower weight, more efficient engine cowl and lower Cd.

Edited September 25, 2005 by pfcem

[whyhow]

nevermind, got it.

Edited September 25, 2005 by whyhow

[JOE BRENNAN]

The only "official" figure for the Frank's speed is that the original prototype attained a top speed of 388mph with the 1,800 hp Ha-45 model 11.

 

Read the original post again.  It makes no mention of which version of the Frank.

 

227011[/snapback]

See my post of the Japanese reference giving 624km/h for Homare 21 as Nakajima information. You're just posting again and again and not reading the responses, and just repeating the generic info from secondary English sources and googling. Everbody who'd be seriously interested in this already knows those sources say or imply 388 applied to Homare 11, and 427 was a "test result from 1946". What's the point of repeating the std English secondary source info again and again?

 

"So how is it that we are to accept that the F4U-1 is capable of 417mph but that it is unrealistic to accept that the smaller... Ki-84-II may be possible of 427mph?""

 

Whereas my comment about the discussion not being about the II is responding to something I did in fact read in your post.

 

Joe

[Guest pfcem]

You're just posting again and again and not reading the responses, and just repeating the generic info from secondary English sources and googling. Everbody who'd be seriously interested in this already knows those sources say or imply 388 applied to Homare 11, and 427 was a "test result from 1946". What's the point of repeating the std English secondary source info again and again?

227103[/snapback]

 

On the contrary, it is you who is not reading the responses.

 

You keep going back to the "427 was a test result from 1946" debate over & over even though I have twice indicated that I am not debating the validity of that.

 

It has been implied here that the Frank wa not a threat to US fighters in 1945 because while they were capable of well over 400mph & the Frank was only capable of ~390mph.

 

My contention is that the Frank was a serious threat to US fighters & even superior in many ways. There is no debate that the Frank could out turn & out climb any US figher at the time.

 

The top speed of the Frank is debatable however. It is obviously faster than the 388mph that the 1st prototype officially achieved. My contention is that its top speed was (based on the Frank's specification & both wartime & posts war reports) comparable with US fighters at the time.

[JOE BRENNAN]

1. You keep going back to the "427 was a test result from 1946" debate over & over even though I have twice indicated that I am not debating the validity of that.

 

2. It has been implied here that the Frank wa not a threat to US fighters in 1945 because while they were capable of well over 400mph & the Frank was only capable of ~390mph.

 

3. The top speed of the Frank is debatable however.  It is obviously faster than the 388mph that the 1st prototype officially achieved.  My contention is that its top speed was (based on the Frank's specification & both wartime & posts war reports)

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1. Well you first indicated a crazy conspiracy theory that the test occurred and yielded more than 427 I read your posts carefully and didn't see where you finally said "oh I didn't realize there was new info casting doubt on 427" before you switched to claiming you'd always agreed that was a questionable piece of info.

 

2. The evidence that the Frank was not a major threat to US fighters, Frank units as they actually existed, is the lack of operational reports indicating that. As mentioned long ago in the thread, the conventional statement that a "good pilot with a Frank could cause lots of trouble", I agree in theory, it's just there's a lack of almost any real incident where that was true in fact, much different than good Tony and Zero pilots could also cause trouble in 1945, of which there are examples.

 

3. You're for about the third time ignoring J source I posted attributing the 624km/h speed to Homare 21 not the prototype, then again simply asserting wartime reports of Franks being faster than US fighters, as opposed to difficult to intercept as fighter-bombers, that don't exist AFAIK (and haven't been cited specifically by anybody here)and then contradicting yourself again switching back to speaking of "postwar reports" you just said you accept may not exist.

 

Joe

Edited September 25, 2005 by JOE BRENNAN

[Guest pfcem]

1. Well you first indicated a crazy conspiracy theory that the test occurred and yielded more than 427    I read your posts carefully and didn't see where you finally said "oh I didn't realize there was new info casting doubt on 427" before you switched to claiming you'd always agreed that was a questionable piece of info.

227184[/snapback]

 

Again, the Ha-45 model 21 was rated at 1,990 hp on "low" octain Japanese fuel. What would it be capable of doing on higher octane US fuel?

 

It is therefor conceivable that the Frank obtained an alarmingly high speed during flight tests using high octain US fuel & that the "report" from those tests used the earlier 427mph estimate rather than the actual speed obtained.

 

 

 

2. The evidence that the Frank was not a major threat to US fighters, Frank units as they actually existed, is the lack of operational reports indicating that. As mentioned long ago in the thread, the conventional statement that a "good pilot with a Frank could cause lots of trouble", I agree in theory, it's just there's a lack of almost any real incident where that was true in fact, much different than good Tony and Zero pilots could also cause trouble in 1945, of which there are examples.

227184[/snapback]

 

On the contrary, there are reports of Franks giving US fighters a great deal of trouble. It seems that people like you simply choose to ignore or dismiss them because there are more reports of Japanese fighters not giving US fighters much trouble.

 

I have already stated that the combat performance of Japanese fighters in 1945 was limited by the capabilities of the Japanese pilots & not the capabilities of the planes themselves. Most Japanese pilots in 1945 simply could not match the flying skills of the majority of US pilots. When a well maintaine Japanese fighter as piloted by a good japanese pilot, they did give US fighters a hard time but again, that combination was few & far between in 1945.

 

 

 

3. You're for about the third time ignoring J source I posted attributing the 624km/h speed to Homare 21 not the prototype, then again simply asserting wartime reports of Franks being faster than US fighters, as opposed to difficult to intercept as fighter-bombers, that don't exist AFAIK (and haven't been cited specifically by anybody here)and then contradicting yourself again switching back to speaking of "postwar reports" you just said you accept may not exist.

227184[/snapback]

 

The Japanese were renound for their misinformation during WW2.

 

Again, the only official top speed rating ever given by the Japanese (that I have ever been made aware of) was the official report by Nakajima that the 1st prototype achieved a top speed of 624km/hr (388 mph). They simply continued to use this number for wartime production aircraft even though they obviously were faster than the original prototype by a good margin.

 

The US did conduct flight tests on many Japanese aircraft after the war, the Frank included. Many of those aircraft did in fact exceed their "official" top speed although I have not read anything specific enough about them to know on what octane fuel the speeds were obtained.

[istvan47]

Just to enterering in this issue, because today my astrological picture is somewhat against those of Joe , i would say something about this funny discussion, rougly: if Hayate was faster until 427 Mph was OK, but it wasn't so it wasn't good enough.

To cut this gordian issue, without an Hayate at our hand let me say something about the speed of WW fighters:

 

-thanks to a favourable wind, an Hurricane before the WWII archieved a cruise speed from an airbase to antoher, of 657 KMH!!

 

-The Bloch 157, built by germans from the pieces made by frenchs in 1940, with a a radial of 1500HP archieved a 710 KMH maximum speed (believe that the windspeed was mounted wrong, like you want)

 

-Above all, Reggiane RE 2005 was tested in orizontal speed measured at 678KMH (and 978 in a dive),

BUT, the "ufficial" max speed in a wartime real aricraft was locked to 628KMH

 

-not to forget, the official speed of the bearcat was around 680KMH, but even so, an example (modiphied) locked over 800 (and 960 in a dive)

 

So, seen above, i cannot be sure if 427 mph -685KMH for non-anglo-saxon brains,

was really archivied, but my opinion was, that there is no evidence that a 2000HP , 3500KG fighter cannot reach such speed, even in particular conditions.

An higher number of octane fuel, just as example, greater than the original projected, is definitively one of such conditions. There was already a biiig difference between 87 and 99 octane, so i think it's totally plausible an increasing of this speed from 390 to 430 MPH. I don't see any reason to make a holy war about this. If japs evalued this fighter at 388 with their fuel, and perhaps at greater weights respects the minimum (warload standard?), so US fuel *must* made better, even with perhaps, some modifics for the engine.

 

 

About the importance of training, also i want say something.

Perhaps, Joe, that the issue of lack of trained pilots was overrated, but you can explain why hell an zero can do better than an hayate in an aerial combat vs 1945 US fighters?

 

I tough that the newer pilots weren't enough trained for the newer high speed interceptors, while the older pilots, even if experienced with older types, were not well suited for newer fighters with almost the doubled weight of the new genereration fighters. There is no reason to think that the real value of the P-47N vs Hayate was 11:1 except if the battle was fought above 11000 mts (perhaps), also because this was even worse than zero vs coursairs. I think that the only real answer to this was the lack of proper training and tactics for the newer fighters. Passing from an hayabusa to an hayate is a big step, and one must be master this. Not forget, Ki 44 was available from 1942 but it was never appreciated like mr. leaf-weight Hayabusa.

 

Third. When he is needed, where is drengnobelprize Otsu? He is unfurtunally drowned in some cyclone disaster perhaps ?

[Ol Paint]

I did find the following posts in searching for information:

http://www.j-aircraft.com/faq/ki84.ht...which%20is%20it[/url]] Posted By: Jomo Stewart <Silo_FT@hotmail.com>

Date: Monday, 10 September 2001, at 7:47 a.m.

 

Hello everyone.

I was looking at some performance figures for the Ki-84-1a and notice three number circulating.

388mph (as per Japanese tests on early production model)

422mph (TAIC from captured Ki-84 at Clark [92 octane])

427mph (at Wright field w/ rebuilt engine? [100 octane])

 

I have heard rumor that the orignal 388 number was done without using water-meth injection, and the engine was run at 2900 RPM instead of the maximum 3000.

 

The 422 number was achieved with the water-meth injection and used japanese 92 octane fuel.

 

Does anyone know the true performance of the Ki-84-1a... or rather the most standard, using the common HA-45 21 engine?

 

Re: ki-84 performance...so which is it?

 

Posted By: Deniz Karacay <denizkaracay@yahoo.com>

Date: Saturday, 15 September 2001, at 10:13 a.m.

 

In Response To: ki-84 performance...so which is it? (Jomo Stewart)

 

I talk from memory so I don't remember the designations but all above might well be true. I don't think that any wartime Ki84 had capacity above 400mph unless, it was very well maintained.

 

Late Ki84s had upgraded engine of 1990hp as opposed to 1800hp (which was hard to get anyway). I assume captured Ki84s were very well maintained and serviced and they appear to be late models with more powerful engines. Lacking paint also increase speed by several miles depending on paint.

 

If you look for Ki84s performance during war regarless of circumtances take 380-390mph at most, usually it is even lower.

 

British performance comparisons

 

Posted By: Graham Boak <graham@boak98.freeserve.co.uk>

Date: Saturday, 22 September 2001, at 5:33 a.m.

 

In Response To: Re: ki-84 performance...so which is it? (Deniz Karacay)

 

In the latest Air Britain magazine Aeromilitaria there is a long (half-page) column summarising the trials carried out using Seafires at Clark Field from May 1945. There was to be a significant number of other US and Japanese a/c in the trials, but because of various problems this was reduced to the Frank.

 

Interesting comments include: the Frank was limited to 250mm manifold pressure and 2900 rpm. It does not state why, nor how much of a limitation this would have been.

The Seafire could match aceleration at 5000ft, they climbed in formation to 15000 ft, the Seafire then reached 20000ft 45 seconds before the Frank. The rate of turn was tested at 5000ft between 160 and 180 knots (presumably indicated not true). The Seafire outturned the Frank fairly easily, combat flaps on the Frank not seeming to provide any improvement.

 

Frank's speed was 330mph at sealevel, 400mph at 20000ft. (with Ha 45 engine). Seafire pilots were advised to take advantage of high speed performance superiority.

 

Frank was difficult to service, panels were not interchangeable and difficult to fit. Poor rivetting, no protection against corossion. The undercarriage was notoriously weak, difficult to maintain, tyres were difficult to remove and the brakes incredibly bad. Pilot vision was poor.

 

Incidentally, the Seafire was judged superior to the F6F and P-51 below 10,000ft - no other information given in the brief article.

 

The source is ADM1/17474. Presumably there will be a similar report in US archives?

 

Found it

 

Posted By: Deniz Karacay <denizkaracay@yahoo.com>

Date: Monday, 24 September 2001, at 11:56 a.m.

 

In Response To: British performance comparisons (Graham Boak)

 

I have pic of NN610, Seafire MkIII with normal wingtips, flying formation with a Ki84, F6F (look like F6F5 but quality and size of the picture is poor, but can't see window behind pilot) and a P51D/K Mustang.

 

IJAAF tests during war shows Ki84 with Homare Ha45-11 of 1800hp did 388mph @ 19,685ft @ 8,576lbs and Ki84II with 1990hp Ha45-23 did 416mph @ 8,495lb.

 

US test a/c did 427mph @ 20,000 ft but at a much lower weight of 7,940lbs implying low fuel load and possibly without ammo.

 

I am not surprised that Seafire III could out do most a/c at low altitude, it was one of the best in that category.

 

Specifications come from Profile Publications #70, Nakajima Hayate Ki84

 

Re: British performance comparisons

 

Posted By: Jim Broshot

Date: Saturday, 22 September 2001, at 6:29 a.m.

 

In Response To: British performance comparisons (Graham Boak)

 

Does the article state which Mark(s) of Seafires were being used?

 

Re: British performance comparisons

 

Posted By: Graham Boak <graham@boak98.freeserve.co.uk>

Date: Saturday, 22 September 2001, at 11:28 a.m.

 

In Response To: Re: British performance comparisons (Jim Broshot)

 

Not directly, but it does give the serials of the two aircraft. NN610 and NN611. At that time and place they would be L.Mk.IIIs. With the light weight and low-altitude rated engine that would explain their performance: at higher altitudes the P-51D would be far superior.

 

OK,OK, I'll go and look for sure! Sturtivant's Aircraft of the FAA confirms this, and names the pilot as Major P. Nelson-Gracie, Royal Marines.

 

There is a colour picture of an NN-serialed Seafire, with BPF roundel/bar but no unit markings, at Clark Field in Jeffrey Ethell's Wings Of War. I can't make out the rest of the serial but have no doubt it is one of the two trial aircraft.

 

Re: British performance comparisons

 

Posted By: Jim Broshot

Date: Saturday, 22 September 2001, at 5:41 p.m.

 

In Response To: Re: British performance comparisons (Graham Boak)

 

Confirmed by SUPERMARINE AIRCRAFT SINCE 1914 (Andrews and Morgan).

 

Seafire Mark III Type 358

 

"250, NN333 to 641, ordered 5 January, 1943, from Cunliffe-Owen as: NN333-367, 379-418, 431-476, 488-528, 542-586, 599-641. Delivered as LF.III."

 

Equipped with Merlin 55M with cropped supercharger impeller giving 1,585hp at 2,750ft.

 

Re: ki-84 performance...so which is it?

 

Posted By: Hiroyuki Takeuchi <hiryu@bigfoot.com>

Date: Tuesday, 11 September 2001, at 1:37 a.m.

 

In Response To: ki-84 performance...so which is it? (Jomo Stewart)

 

The Ha45 was designed to use 100 octane or at least 92 octane fuel but most IJA fuel was around 87 octane and probably even worse towards the end of the war. That means the motor had to be run on less boost and less power. Since the engine quality and airframe finish were also suffering, that all reflected upon performance. Writer Minoru Akimoto mentions that some Hayates in service conditions were lucky to achieve 600km/h (370mph). No wonder the 580km/h (360mph) Ki100 is often touted as the being better than the Ki84.

 

So while the Ki84 design had a 420mph potential, elements of reality (poor fuel, faulty engines, rought airframe finish, etc) often limited its performance to a lower level. May be the 624km/h (388mph) figure is about right after all.

 

Re: ki-84 performance...so which is it?

 

Posted By: richard dunn <rdunn@rhsmith.umd.edu>

Date: Monday, 10 September 2001, at 3:01 p.m.

 

In Response To: ki-84 performance...so which is it? (Jomo Stewart)

 

Don't know about "true" but I'll give you what I found upon glancing at my files. A technical notebook captured at Clark Field (ADVATIS No. 92) has rather complete data on the Ki 84, however, it is undated and its source uncertain. Max speed is given as 624 kph (=387.5 mph). This is at 6550 meters altitude, 2900 rpm and +250 boost. Fuel is given as 92 octane and the capacity of the methanol tank is mentioned in the report. Unfortunately another tech manual on the Ki 84 is published in mimeographed form, completely sourced and dated, gives great technical detail, but no performance data.

 

Two POW reports comment on Ki 84 performance. One POW (who flew the Ki43-2) says max speed for the Ki 84 is 650kph true and 550 indicated at 5000 meters. Another POW, a Ki84 pilot, says max speed is 700kph true and 600 indicated. He gives no altitude and says he has never flown faster than 550 kph indicated. Those speeds equate to about 404mph and 435mph respectively.

 

My impression (not just for the Ki 84) is that many Japanese fighter pilots flew their aircraft in combat beyond "book" specifications and got away with it.

 

Sorry, I can't answer your question with any certainty! The boost and rpm data above may give some clue, though.

 

Re: ki-84 performance...so which is it?

 

Posted By: Jukka Juutinen

Date: Tuesday, 11 September 2001, at 2:16 a.m.

 

In Response To: Re: ki-84 performance...so which is it? (richard dunn)

 

You mentioned boost of "+250". Is it in millimetres of mercury? That seems as the only reasonable option. If it is, the boost is a bit low for a max speed condition (about 40 inHg absolute). Or did the Japanese use some different unit of pressure than any other?

 

Re: ki-84 performance...so which is it?

 

Posted By: richard dunn <rdunn@rhsmith.umd.edu>

Date: Tuesday, 11 September 2001, at 6:36 a.m.

 

In Response To: Re: ki-84 performance...so which is it? (Jukka Juutinen)

 

I have seen US translations of Japanese documents equate +150 to 35.4 in. Hg and +200 equated to 37.8 in. Hg. So I surmise that US technical personnel cosidered Japanese pressure measurements to be in mm of mercury as you state.

 

As indicated in my comments above, I doubt Japanese pilots in combat respected these numbers as limitations. In the Zero 21 +200 was take off power and was not an authorized rated power otherwise. But this is also the "overboost" power that we read about Sakai using so often in "Samurai." Combat reports seem to indicate Zero pilots routinely used this power in combat (smoke trails coming from Zeros in critical situations) and I believe they used it for 10 minutes or more continuosly based on some incidents I have read about. Their a/c were regulated not to exceed this boost. Incidentally the Akutan Zero was tested at +150 and not +200 (engine ran rough at 38" Hg and they were afraid of losing the aircraft).

 

POW reports indicate that while 92 octane was the standard fuel for many fighter aircraft, they had 95 and 97 octane fuel as well. They also had some captured 100 octane fuel early in the war (don't know if they produced any later). The 87 octane fuel was authorized for use in high performance aircraft only in transfer flights and the like at low rpm.

 

This is getting a bit off point but we may need to rely on general background unless someone can come up with direct evidence.

 

pfcem,

 

I don’t think anyone is arguing that the Ki-84 couldn’t be competitive. What is being argued is your claim that it could “outrun, out climb, and out maneuver” the Allied fighters. “It is therefor conceivable that the Frank obtained an alarmingly high speed during flight tests using high octain US fuel & that the "report" from those tests used the earlier 427mph estimate rather than the actual speed obtained.” Alarmingly high speed? Give me a break. Where is the incentive for the US to be so concerned about a 420mph Japanese fighter when the US is fielding fighters in the 460-490mph range (P-47N, P-51H, F8F, F2G) and jets (F-80 flew in 1944 and was in service by the end of the war, including examples in Europe and 30 shipped to the Philippines in mid-1945, although they didn’t see combat)? You are postulating that a Japanese fighter, burning fuel unavailable to the Japanese scared the USAAF so badly that they have covered this up for 60 years? Richard Young at least has the decency to pick a much more significant event to theorize conspiracies about.

 

istvan47,

 

This discussion has nothing to do with "can't," it is a question of what was actually achieved versus test results. At the moment, we are lacking definitive data from tests that may/did occur and the provenance of the numbers is what is being questioned, not differences in the laws of physics when changing sides of the Pacific. The source of the performance numbers is important when trying to guess potential performance under actual wartime conditions, as there are significant differences between aircraft with no weapons & ammo, freshly overhauled, and tested in the rear areas with good fuel vs. combat loaded aircraft with significant hours & questionable fuel. This is true for both sides.

 

Douglas

[Guest pfcem]

I don’t think anyone is arguing that the Ki-84 couldn’t be competitive.  What is being argued is your claim that it could “outrun, out climb, and out maneuver” the Allied fighters.  “It is therefor conceivable that the Frank obtained an alarmingly high speed during flight tests using high octain US fuel & that the "report" from those tests used the earlier 427mph estimate rather than the actual speed obtained.” Alarmingly high speed?  Give me a break.    Where is the incentive for the US to be so concerned about a 420mph Japanese fighter when the US is fielding fighters in the 460-490mph range (P-47N, P-51H, F8F, F2G) and jets (F-80 flew in 1944 and was in service by the end of the war, including examples in Europe and 30 shipped to the Philippines in mid-1945, although they didn’t see combat)?  You are postulating that a Japanese fighter, burning fuel unavailable to the Japanese scared the USAAF so badly that they have covered this up for 60 years?  Richard Young at least has the decency to pick a much more significant event to theorize conspiracies about.

229520[/snapback]

 

On the contrary. There are those here who are saying that the Frank couldn’t be competitive & they are using the "388mph" top speed as their primary argument for it.

 

Again, 2000 hp & 8500 lbs in a comparatively small & aerodynamic (for a radial-powered aircraft) package. If most knowledgable people were given those specifications for a US or British WW2 fighter they would likely assume that plane would be easily capable of going faster than 425mph (possibly as much as 450mph). Again using the F4U-1 as an example: 2000 hp & 12,000 lbs = 417mph.

 

And that engine power rating is with Japanese "low octain" fuel. What do you think a Ha-24 model 21 or 23 was capable of with high octain US fuel?

 

Yes a 420mph Japanese fighter would not be a major concern for the US in 1946 but admitting that in 1945 a Japanese fighter was capable of speeds similar to the F4U-4 (for example) would be.

 

Name a 1945 US aircraft that could turn or climb with a Frank. The only one I can think of that possibly could would be the F8F Bearcat but we had very few of them & they were all on the US west coast, not in the Japanese theater.

[MiloMorai]

Hard to get top peformance out of a 2000hp engine when one moment the oil temp would be normal and the next it would be over 85C.

[Ol Paint]

On the contrary.  There are those here who are saying that the Frank couldn’t be competitive & they are using the "388mph" top speed as their primary argument for it.

Source, PLEASE. I just re-scanned the entire thread and there has been no argument made by anyone, other than yourself, that the laws of aerodynamics & physics are different based on the country of manufacture. What I do see is arguments made that the 427mph number could be calculated, rather than tested performance, but the documentation is lacking to back up either position. I also see arguments being made that the Ki-84 would not be likely to get the maximum performance out of the engine in Japanese wartime service due to the difference in octane--this factor has a major impact on performance.

Again, 2000 hp & 8500 lbs in a comparatively small & aerodynamic (for a radial-powered aircraft) package.  If most knowledgable people were given those specifications for a US or British WW2 fighter they would likely assume that plane would be easily capable of going faster than 425mph (possibly as much as 450mph).  Again using the F4U-1 as an example: 2000 hp & 12,000 lbs = 417mph.

 

And that engine power rating is with Japanese "low octain" fuel.  What do you think a Ha-24 model 21 or 23 was capable of with high octain US fuel?

First of all, there is more to speed than power & weight. Low wing loading that is so helpful for low-speed maneuvering can actually be a hindrance due to the increase in induced drag. There is a reason that the F-105 and F-111 are pretty much uninterceptable on the deck.

 

Second, IF we accept that the 427mph IS a US test figure, then we KNOW what difference high-octane fuel makes. If it is NOT a test, but a calculation, then the octane difference becomes debatable, because you need to know what assumptions were made in the calculation. Note also that one of the posts I swiped is claiming 422mph on 92 octane and 427 on 100. Again, the provenance of the numbers makes it difficult to decide what factors to apply, but I haven't run across anything to show superior speed to Allied fighters.

Yes a 420mph Japanese fighter would not be a major concern for the US in 1946 but admitting that in 1945 a Japanese fighter was capable of speeds similar to the F4U-4 (for example) would be.

You're having problems with your reading comprehension, again. The fighters I listed were coming on line in 1945, not 1946--again, there were P-80s in the PTO in 1945.

Name a 1945 US aircraft that could turn or climb with a Frank.  The only one I can think of that possibly could would be the F8F Bearcat but we had very few of them & they were all on the US west coast, not in the Japanese theater.

229552[/snapback]

So now it is US aircraft... I was going to mention the Spitfire XIV. The F7F, and the P-38L can probably give the Ki-84 a run for its money under actual wartime conditions (I don't know what GregShaw has calculated for the P-38 performance, but it is more than the commonly listed numbers--US fighter performance figures were published using MIL power settings, not WEP).

 

The other thing you need to remember is that US fighters were operating with pretty effective fighter direction systems, which is what all those radar picket ships were doing off of Okinawa. Generally speaking, US fighters flying CAP were going to open the fight with the odds stacked in their favor, probably flying at higher altitude than the Japanese fighter. All the climb rate in the world below 20,000ft isn't going to help your case when that F4U, or P-51, or F6F comes dropping down from 30,000...

 

I'll grant the climb rate, but not necessarily turn rate at all airspeeds. The P-38L has a high wing loading, but thanks to the flaps, has a pretty good reputation for maneuverability. The F6F is another that could probably give a Ki-84 problems in a turning fight. I'll state again that no proof has been given that the Ki-84 could completely outfly any aircraft in the Allied inventory in all aspects. It has parity, or less, in speed, better climb performance, maneuverability is unknown (wing area comparisons aren't enough to claim superiority), dive performance is unknown. Nope, no world-beater here. Just a good fighter that finally leveled the hardware playing field (at best), but came along a bit too late.

 

Look for conspiracies elsewhere.

 

Douglas

[hojutsuka]

On the contrary.  There are those here who are saying that the Frank couldn’t be competitive & they are using the "388mph" top speed as their primary argument for it.

 

Again, 2000 hp & 8500 lbs in a comparatively small & aerodynamic (for a radial-powered aircraft) package.  If most knowledgable people were given those specifications for a US or British WW2 fighter they would likely assume that plane would be easily capable of going faster than 425mph (possibly as much as 450mph).  Again using the F4U-1 as an example: 2000 hp & 12,000 lbs = 417mph.

229552[/snapback]

You seem to base a lot of your position on this. But speed is a matter of available power versus drag rather than available power versus weight, and light weight does not necessarily translate to low drag. Furthermore, the drag-versus-speed curve varies for every aircraft, and tends to be highly nonlinear. So just because aircraft A has more power per weight than aircraft B does not mean aircraft A will be faster than aircraft B.

 

To see what this means, let us look at some real life examples.

 

We will start with Ki-61 Hien. This is a Japanese Army fighter, and in its Ki-61-I KAI Otsu version it was powered by a Kawasaki Ha-40 (license production version of the German DB 601) producing 1180hp for takeoff and had a loaded weight of 3470kg, for a power loading of 2.94kg/hp. The Ki-61-II KAI Ko was a further development, with the same wing, a slightly modified fuselage, and an improved Ha-140 producing 1500hp for takeoff and a loaded weight of 3780kg, for a power loading of 2.52kg/hp. The top speeds were 590km/h for the Ki-61-I KAI Otsu and 610km/h for the Ki-61-II KAI Ko, or less than 13 mph difference in spite of the significant difference in power loading.

 

Thus a reduction in power loading from 2.92kg/hp to 2.52kg/hp with basically the same airframe produced an improvement of less than 13mph in top speed.

 

Now let us look at another airframe, this time the P-51B, powered by Packard-built Merlin V-1650-3 rated at 1298hp and having a loaded weight of 11,200lbs (or 5080kg), for a power loading of 3.90kg/hp. If you go by power loading, the P-51B must surely be much slower than even the Ki-61-I KAI Otsu. The truth of course, is that the P-51B is much faster, at 440mph (708km/h) at 30.000 feet. Even taking the speed of the P-51B at the sort of lower altitudes where the Ki-61 is rated, we have 424mph (692km/h) at 15,000 feet.

 

The P-51B is actually fairly close to Ki-61-II KAI Ko in overall size, having less than 10% more wing area, but weighs a lot more and has less power. In spite of this, the P-51B airframe has a lot less drag, so is much faster.

 

Hopefully these examples will convince you that simply comparing power loading does not really say much about maximum speed.

 

And that engine power rating is with Japanese "low octain" fuel.  What do you think a Ha-24 model 21 or 23 was capable of with high octain US fuel?

 

Yes a 420mph Japanese fighter would not be a major concern for the US in 1946 but admitting that in 1945 a Japanese fighter was capable of speeds similar to the F4U-4 (for example) would be.

 

Name a 1945 US aircraft that could turn or climb with a Frank.  The only one I can think of that possibly could would be the F8F Bearcat but we had very few of them & they were all on the US west coast, not in the Japanese theater.

229552[/snapback]

pfcem, if you were to say that the Ki-84 Hayate was a very good piston-engine fighter design for its period, I would agree with you whole-heartedly, and I think most people posting here would also. If the Ki-84 had been made from decent materials by competent labor, maintained by experienced mechanics, fueled with high-octane gasoline, and flown by well-trained pilots in equal numbers against U.S. fighters (say P-51Ds) in 1944, I think the fight would have been very close, and I would not venture to guess which side would come off better.**

 

But the reality in 1944 was that none of these conditions were present. Japan had hit the limit in basic materials production, and to maintain numbers had to accept reduction in quality. One well-known example is the inferior steel used in landing gear legs, which often snapped on landing and wrote off many otherwise undamaged Ki-84s and pilots. The Japanese military did not fully understand the necessity for wartime production, so conscription did not make adequate allowance for leaving skilled workers in their war-critical jobs. This plus the expansion of production made necessary by war meant that the Ki-84 was largely produced by new workers, sometimes women and school kids, who did not have the experience and training required to do a good job. With inferior materials and inadequately skilled labor, the results were predictable, the aircraft that did get produced were unreliable and unable to meet their predicted performance.

 

These inferior aircraft were sent to units that were largely staffed with inadequately trained mechanics and pilots thanks to heavy combat losses and to the Japanese military's inability to forecast the need for greatly expanding the training establishments to cope with the war demands. The few remaining experienced Japanese pilots generally found themselves outnumbered after the initial contact with enemy fighters, because the inexperienced Japanese pilots that formed the majority of Japanese formations by this time were rapidly shot down or were unable to remain in contact as soon as the enemy attacked.

 

The Japanese were short of fuel, and certainly did not have the 110-130 octane gasoline available to the U.S. aircraft, so even given equal aircraft and pilots, the Japanese would have been at a disadvantage.

 

So the reality is that an "average" Ki-84 in 1944-45 simply was no match for the better U.S. fighters like the P-51D, and this added to the difference in average pilot quality and lack of high octane fuel just made it impossible for the Japanese to even come close in air combat.

 

Hojutsuka

 

** Even granting that the Ki-84 could out-turn and out-climb the P-51D, it is not clear that the Ki-84 would actually be decisively superior in air combat because there are more factors to combat capability than pure speed, climb rate, and maneuverability. The Spitfire Mk XIV had a 2035hp Griffon 65 and a loaded weight of 8500lbs, almost exactly what you have for the Ki-84. It was slightly faster than the P-51D at altitude (448mph at 26000 feet versus P-51D's 437mph at 25000 feet), climbed faster, and turned better. In essense the Spitfire Mk XIV was to the P-51D what the Ki-84 might have been with decent manufacture, maintenance, pilot, and high octane gasoline. But Captain Eric Brown, who had flown both the Spitfire Mk XIV and the P-51D, points out that the P-51D had a better rate of roll and faster acceleration in a dive (advantages that I would expect the P-51D to have over the Ki-84 as well), and while personally perferring the Spitfire (he is a Brit, after all ), he does not see a clear advantage for either if they were matched in combat.

[Guest pfcem]

Source, PLEASE.  I just re-scanned the entire thread and there has been no argument made by anyone, other than yourself, that the laws of aerodynamics & physics are different based on the country of manufacture.  What I do see is arguments made that the 427mph number could be calculated, rather than tested performance, but the documentation is lacking to back up either position.  I also see arguments being made that the Ki-84 would not be likely to get the maximum performance out of the engine in Japanese wartime service due to the difference in octane--this factor has a major impact on performance.

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YES THEY ARE. Buy claiming that a fairly small 8500 lbs plane with 2000 hp is not capable of high speed (choose whatever speed you like you) but they have no problem accepting that a larger & heavier F4U-1 (12,000 lbs) with similar power is capable of 417 mph.

 

 

Second, IF we accept that the 427mph IS a US test figure, then we KNOW what difference high-octane fuel makes.  If it is NOT a test, but a calculation, then the octane difference becomes debatable, because you need to know what assumptions were made in the calculation.  Note also that one of the posts I swiped is claiming 422mph on 92 octane and 427 on 100.  Again, the provenance of the numbers makes it difficult to decide what factors to apply, but I haven't run across anything to show superior speed to Allied fighters.

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Again, there are very few people who actually believe that a Frank obtained a top speed of 427 mph during US flight tests in 1946. Most believe that the 427 mph figure came from an earlier calculation but why would that figure be used rather than the actual speed obtained. My contension is that the Frank most lilkely went FASTER than 427 mph on high octane US fuel but that the earlier 427 mph figure was used since it was believed that Japan did not have fuel of such high octaine fuel & therefor the speed that was obtained in the test was irrelivant.

 

 

You're having problems with your reading comprehension, again.  The fighters I listed were coming on line in 1945, not 1946--again, there were P-80s in the PTO in 1945.

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No it is you with the reading comprehension problem.

 

The US conducted flight tests on numberious Japanese aircraft in 1946. Prior to that we actually new very little about them. In 1946 the US government was unwilling to admit (to the general puplic) that Japan was capable of producing a fighter equal to or superior to the planes we were flying at the time.

 

 

So now it is US aircraft...  I was going to mention the Spitfire XIV.  The F7F, and the P-38L can probably give the Ki-84 a run for its money under actual wartime conditions (I don't know what GregShaw has calculated for the P-38 performance, but it is more than the commonly listed numbers--US fighter performance figures were published using MIL power settings, not WEP).

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THANK YOU for mentioning Spitfire XIV. Now here we have an aircraft with similar characteristics to the Frank. Engine output, overall dimensions, weight, just about every phisical characteristic between the two are similar. The main difference being that the Spitfire uses an inline engine while the Frank uses a radial.

 

This would (in theory) indicate that the 446 mph Spitfire XIV would be somewhat faster than the Frank due to its potentially lower Cd.

 

Of coarse the F4U & P-47 were powered by a LARGE radial engine yet that somehow managed to obtain very high top speeds.

 

The other thing you need to remember is that US fighters were operating with pretty effective fighter direction systems, which is what all those radar picket ships were doing off of Okinawa.  Generally speaking, US fighters flying CAP were going to open the fight with the odds stacked in their favor, probably flying at higher altitude than the Japanese fighter.  All the climb rate in the world below 20,000ft isn't going to help your case when that F4U, or P-51, or F6F comes dropping down from 30,000...

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I am trying to get people to judge the Frank on its own merit not on the fact that there were so many factors unrelated to the flight performance of the planes themselves that contributed to high alllied kill/loss ratios in 1945.

 

 

I'll grant the climb rate, but not necessarily turn rate at all airspeeds.  The P-38L has a high wing loading, but thanks to the flaps, has a pretty good reputation for maneuverability.  The F6F is another that could probably give a Ki-84 problems in a turning fight.  I'll state again that no proof has been given that the Ki-84 could completely outfly any aircraft in the Allied inventory in all aspects.  It has parity, or less, in speed, better climb performance, maneuverability is unknown (wing area comparisons aren't enough to claim superiority), dive performance is unknown.  Nope, no world-beater here.  Just a good fighter that finally leveled the hardware playing field (at best), but came along a bit too late.

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The Frank had combat flaps too (those magical devices that gave the Spitfire, Hellcat & P-38 - not to mention most Japanese aircfaft there good maneuvering performance). So here again we are to believe that US (& British) planes are superior to the Frank because of their combat flaps but it is somehow irrelivant that the Frank also had combat flaps.

 

I am not saying that the Frank was superior to all allied aircraft in all aspects. What I am saying is that as an all-round fighter it was easily a match for allied fighters & was even superior in some respects.