F6F-5 vs J2M3

[krieghund]

As promised I finally scanned this comparison. I got it in the mid 1980's there were to be others but when I wrote the author he said he had poor reviews and decided not to do any others. I suspect he wrote the P40C vs A6M2 comparison in the early 1970s.

Anyway enjoy

 

[CliffyB]

Thanks for the post man! Some really neat info in there and love the photos of the captured Jack!!!!! Now does anyone make a kit of one?

 

[Civettone]

Only read the first half but love it. It is really the type of literature I can appreciate. No nonsense.

I wonder though how computers and computer models in those days were accurate enough.

Kris

 

[FLYBOYJ]

Only read the first half but love it. It is really the type of literature I can appreciate. No nonsense.

I wonder though how computers and computer models in those days were accurate enough.

Kris

Bill M. can answer that!

 

[Civettone]

No one could do it better!


(I also noticed I wrote 'how' while I meant 'if')
Kris

 

[tomo pauk]

Such a simple way to talk about the complicated issues. Many thanks

 

[Gaston]

I dont disagree with the conclusions here, but how they were drawn: Would his method have predicted the poor turn performance of the N1K1 George, whose pilots described a severe handling problem that in hard turns could induce an unpredictable wobbly "autorotation", even with automatic flaps deployed, and that this was a major drawback of the type, so much so that the N1K1 was used mainly in boom and zoom attacks and on the vertical plane?

I doubt it...

Gaston

 

[Civettone]

Interesting. Was this fixed with the N1K2-J ?


Kris

 

[Glider]

My respect for the J2M3 has increased a lot with this. I admit that I always had it as a bit of a brick in terms of agility, wrong again but thats how you learn.

 

[Civettone]

What I also like about the Raiden and which is not mentioned is that it was a powerful but also reliable engine. The japanese had the Kasei engine already mid war but was only for their bombers, as it was too big for fighter aircraft. They succeeded in getting it into this aircraft. The other fighters like the Ki-84 and N1K2J as well as most of the projected fighters had the less reliable Homare engine.

Kris

 

[Ivan1GFP]

I believe the straight line performance of the Raiden is WAY understated here. US tests make this aircraft MUCH faster than is quoted here. TAIC 105B Data sheet on Jack 21 states 359 mph (WEP) at sea level, 417 mph (WEP) at 16,600 feet. This plane will hit 385 mph while carrying a 250 liter drop tank.

- Ivan.

 

[slaterat]

Wow, what a great article thanks for posting it.

 

[icepac]

One thing we should probably take with a grain of salt is the japanese pilots' opinion of the handling of the late war interceptors.

These guys flew the zero or ki43 before transitioning into the j2m3, ki84, and N1K2 so thier opinion of the "handling" is purely by comparison to previous models flown.

 

[snowmobileman]

Interesting article! I know this is years old, but I noticed that the author listed the F6F-5 ceiling as 31,000', and that was a major performance detriment in his opinion. The numbers I have seen from WW2aircraftperformance list the ceiling at 38,000', give or take. That might even things out a bit...

 

[swampyankee]

Only read the first half but love it. It is really the type of literature I can appreciate. No nonsense.

I wonder though how computers and computer models in those days were accurate enough.

Kris

For the gross behavior of external airflow, the models and computers were probably accurate enough if the boundary layer was reasonably well-behaved, which it should be at low-angle of attack conditions, i.e., don't trust any predictions of separation, and the drawings accurately represented the built aircraft and the drawings could be accurately digitized. For internal airflows, like cooling, the models of that time were not accurate enough to predict things like pressure losses through radiators (liquid-cooled) or cylinder baffles (air-cooled). They would also be unreliable when predicting flow over things like open wheel wells, various drags due leaks, and gun ports, all of which may cause local separation.

The main shortcoming with the computers would be that their memory limits -- the mainframe at my college had only about 0.5 mebibytes of core (random-access memory) and about 30 mebibytes of drum (== hard disk) storage. Modern computers have much more memory and storage, so the models can be much more detailed. Their computational accuracy, from a purely numerical standpoint, was probably as good as today's (my college mainframe had 96-bit doubles), although the algorithms weren't as well-behaved under some conditions.

 

[Ivan1GFP]

I dont disagree with the conclusions here, but how they were drawn: Would his method have predicted the poor turn performance of the N1K1 George, whose pilots described a severe handling problem that in hard turns could induce an unpredictable wobbly "autorotation", even with automatic flaps deployed, and that this was a major drawback of the type, so much so that the N1K1 was used mainly in boom and zoom attacks and on the vertical plane?

I doubt it...

Gaston

I believe this isn't really a poor turn performance problem as an inadequate directional stability problem.
Yes, this problem was corrected in the N1K2-J. In fact, I suspect it was over corrected in the N1K2-J which might explain why the N1K2-J-Ko had a reduced chord fin.

I believe the biggest problem with this report is "Garbage In == Garbage Out". The performace of J2M3 is way under what the real aircraft could do.
The issue with F6F service ceiling is probably because it was reported for 500 fpm rather than 100 fpm.
(Just a guess.)

- Ivan.

 

[DarrenW]

I got it in the mid 1980's there were to be others but when I wrote the author he said he had poor reviews and decided not to do any others.

That's too bad because it looks like he went through a great deal of work to arrive at his conclusions. The author probably lost a lot of folks when he called the Hellcat a mediocre airplane. This is pure nonsense as "mediocre" airplanes don't perform nearly as well as the F6F did throughout it's career. I never heard of any Hellcat pilots complaining that they were totally overwhelmed by the sheer performance of Japanese fighters, and this includes the J2M. Maybe his computer models were flawed and this caused him to lose credibility? He may have also had an ax to grind or that he simply was a huge fan of Japanese WWII aircraft. I tried to find the author's name in the publication but it seems he chose to remain anonymous. Pity.

Besides typos the most obvious error regarding the technical data presented was concerning the altitude performance of the Hellcat. By presenting an incorrect service ceiling for the F6F-5 (off by at least 6,000 feet) all of his calculations at altitude became instantly invalid. How many other incorrect performance specifications were fed into his computer, leading to erroneous results?

One other thing of note is that the author was quick to regurgitate the now thoroughly debunked fictional tale of Ensign Kaneyoshi Muto's epic "twelve against one" dogfight on 16 February 1945. In reality he wasn't flying alone but was with a mixed group of at least nine other A6Ms, J2Ms, and N1Ks from the Yokosuka Air Group when they met seven VF-82 Hellcats from the USS Bennington. Due to an overzealous Japanese press Muto was likened to a samurai warrior of old and was incorrectly given sole credit for all four Hellcats brought down over Astugi that day. Complete and utter propaganda.

Too bad the author failed to mention that Muto was eventually shot down on 24 July 1945, during his very first combat mission with the 343rd Air Group. On that day there were a total of six N1K2s lost during a furious dogfight over Bungo Channel. At least one of these was awarded to Hellcat pilot Lt Malcolm Cagle of VF-88 who was involved in the dogfight with Muto, while two others went to Lt(jg) Robert Applegate of VBF-1 flying a Corsair. A Hellcat and three Corsairs were brought down in the action as well, which included Applegate. It is highly probable that Muto and Applegate shot each other down in a head-on pass, but this cannot be fully substantiated.

Source: Genda's Blade: Japan's Squadron of Aces, 343 Kokutai (Sakaida and Takaki)

The Japanese Navy concluded fairly early on that the N1K was superior to the J2M in most every respect and the majority of Japanese historians will agree with this notion. The author's assertion that the Raiden was the equal of the Shiden and could easily handle a Hellcat just doesn't hold any merit, especially when he fully admits the former would need a reliable power plant to do so.

Noted aviation historian Henry Sakaida said that many Japanese pilots openly despised the Raiden because of it's lack of maneuverability, stating that it could not survive against a Hellcat or a Mustang in a dogfight. That's a pretty powerful statement to the overall inferiority of the J2M to other late war Japanese designs and allied types alike.