Why are the Japanese planes so slow?

[Kweassa]

A lot of heated debates since the introduction of the Ki-84, which got me thinking.

 Why are the Japanese planes so slow? What's the reason? Let's leave the quality issues out - a pure design/specification point of view.

 Some people consider that the A6M was an accident, or a "freak of nature", but however, if the plans for the A6M didn't just drop out of the sky, from a 1940 perspective the A6M2 was one of the fastest fighters in the world. Somehow, even with additional pilot protection I think it'd still be faster and more maneuverable than its main nemesis F4F-3.

 Sure, they were severely limited at high speeds, but in the early days of the war even the Bf109E or the SpitI isn't free from the vice.

 How about the Ki-61? The Ki-61 is a good deal slower than most contemporary planes but considering it uses a DB601A, if it had more power I think it could have been a wonderful plane. Add all the extra weight and stuff and still, the benefit of speed increase would outweigh all that is lost,  as per the case with the Bf109G-6 compared to the G-10.

 Again, I'm not an engineer, but taking a glance, seeing how they perform, I don't think Japanese engineers and lab boys were all too inferior in the designing category.

 Or, was it the design emphasis on maneuverability that killed the speed? But its not impossible to make a very fast plane with large wings that can turn.. - like the Spit9. In 1943 and '44 the Spit9 wasn't too shabby in the speed category either. Neither is the Spit14.

 Or, is it basically impossible to make such a plane with large round/rectangular wings, instead of Spit-like elliptical wings?

 Then is it the engines? While it took some time, the Japanese did create engines with power rating over 1600hp, 1800hp, even upto 2000hp - which in this case, the Ki-84 with the Ha-45-21, is recorded at 427mph.

 Is it the weight? The Japanese fighters were never heavy in all their existence, IIRC.

 Then what is it? The small props? Was there a problem with fitting big props? But not even the prototypes which I suspect might have tried out different types of props, ever recorded speed anything close to its american contemporaries.

 So why are they so slow? USN planes that go over 400mph max speed have entered combat since 1942, and look at the Japanese planes, with the exception of the "ideal" Ki-84 none of what they had ever broke past the 400 marker?

 What was the cause?

[Furball]

no idea, taking a guess at poor workmanship/materials/maintenance/fuel on later war aircraft?

[eddiek]

I'm no expert by any means.......
But from what I have been able to summarize from reading over the past 25-30 years, the Japanese placed more emphasis on maneuverability, i.e. "dogfighting" capability, than on the other areas, such as speed, durability, etc.
It wasn't til the latter stages of the war in the Pacific that they began to come around to the Allied way of thinking and started producing fighters that were better in the speed department.  IIRC, initial response from the veteran Japanese aces, when testing the new planes such as the J2M3, Ki84, and other next generation fighters, was less than favorable.  They mostly wanted a plane that turned on a dime like the A6M series, and did not like the decreased turning capabilities, even though the newer planes were more on a par with US fighters.  
I call it the "old school" way of thinking, or the samurai mentality, that aerial combat was supposed to be more along the lines of the epic WW1 dogfights.  Times had changed, as well as tactics, and the typical Japanese pilot, and his training, had not kept up.  Manufacturers pretty much produced aircraft based on what their pilots said they wanted/needed, and if the pilots did not recognize the change in tactics and requirements, the manufacturers would not either.  
Therefore, the Japanese equipped their air forces with aircraft suitable to dominate a swirling, WW1 type engagement, a dogfight, while the Americans and British moved on and adapted to the times, even dictated newere doctrine in some cases, and went for speed and durability.

Like I said, I am no expert, but that is my opinion.

[Angus]

Lack of Power and drag?
Look at a6m2, which is in it's hayday at the same time as the 190A5. A lot of horses between those two.
And even when the Japanese pushed to 2000hpm the Americans had been there for a couple of years.
And what was the normal combat power on low grade fuel?

Just a guess though....

[GScholz]

Japanese aero engines were definitively behind the times. The Ki-61 would have been a great fighter had it had an engine comparable to the contemporary British/US/German ones. Instead it had the same engine that the 109E-4 had.

Also their emphasis on low speed manoeuvrability hurt their designs in the high-speed regime. If they had put 190 wings on the Ki-84 or Nikki they would have ruled. Also the Japanese designers seemed unable to design control surfaces that worked well both at low- and high-speed.

[VO101_Isegrim]

I guess it`s a combination of large wings, navalisation (hook etc.), relatively weak engines. they also lacked good superchargers, and note that all the fastest fighters could develop those speeds at high altitudes, where the air is thin.. and add to that, generally a radial engine with high drag was used - the spitty may have large wings, but it benfits from having a narrow inline engine in comparision. Plus the rough conclusion I arrived to from the drawings I have seen, no Japanese fighter was a perfection of aerodynamics.. quite a few drag creating parts on them. And all of these factors just strengten each other if combined...

[humble]

How about the Ki-61? The Ki-61 is a good deal slower than most contemporary planes but considering it uses a DB601A, if it had more power I think it could have been a wonderful plane


Actually I think its already an outstanding plane. Obviously it would benifit from more power but its a match for any plane in the set under most circumstances. It's got great visability coupled with relatively "vice free" handling. Flown correctly it will convert most "positive" situations well and provides a good enough platform to handle "negative" encounters as well. The lack of topend speed limited power make life amongst the horde difficult but unless your in a tempest or 262 even lala's and tiffies get run down by higher faster lala;s and tiffies:).....

[GScholz]

It's not a match for any of its contemporary Allied or German fighters. They are far superior in everything but range and in some cases manoeuvrability.

[Angus]

Think of something though.
The A6M is a navalized plane.
It's engine is rather small.
Yet it had an incredible range, versatility, and general performance compared to it's contemporaris.
It's mostly top speed and high speed handling that suffers, in the other areas it's shining.
Now think of other stuff the Japanese had in the air in 1942 and even later, like the Nate or the early Oscar. Compare that to the Spit VIII, the 109G, the 190A8 and so on. A bit confusing.

I am pretty sure that what somewhat affected the japanese aero-design and manufacture in those years was rivalry between different departments (i.e. navy-army), and I've seen that on print somewhere. Interesting if someone has some material about this.

[humble]

Originally posted by GScholz
It's not a match for any of its contemporary Allied or German fighters. They are far superior in everything but range and in some cases manoeuvrability.

It depends on what context you put that comment in...in real world terms...yup. As it relates to gameplay in an artificial enviornment somewhat less so. The Jabo capability is effected in that you cant take out a VH or other hanger but otherwise its still decent. As a fighter you can engage anything in the game 1 vs 1 or in smaller encounters. It's actually not a bad ride in the MA at all....In gameplay or in the real world the pilot is/was the most important performance part of the aircraft. The japanese had a dismal record vs the americans because of the overall poor quality of pilots compared to the allies. Very little cohesion or teamwork. Once that 5% supply of natural aces was worn down the rest were just so much cannon fodder in the face of superior doctrine and training....

[flakbait]

Isegrim, engine type (radial vs inline) could be debated ad nauseum. The P-47M could hit nearly 500mph, and used a radial engine four feet across to do it. The B-29 had four of THE biggest (3,350 cubic inch, 5 feet across) radials out there, and did more than any other bomber could. It really depends more on the quality of manufacture or design of an engine, rather than the engine type.

As for why the Japanese aircraft were so slow, you got me on that one. Comparing the Bf-109E to the A6M3 really is cause for a lot of head-scratching. Both had engines that produced roughly the same amount of horsepower (1,175 vs 1,130) and both were within 9mph of the same top speed at the same altitude. Not bad, but the A6M3 was designed in '41 and put into combat use in July of '42. By July of 1942 the 109G2 was in full production, which was a full 50mph faster than the Zeke 32 (388mph vs 338 mph). Comparing the Ki-61 to any 109 mark is almost as confounding. The Ki-61-KAIc was first built in January of '44, the same year the US, Brits, and Germans were readily breaking the 400mph mark. But the Hien could only wheeze out 366mph at 13,980 ft. That's no better than a 1941 P-39D at 7,500 feet!

You'll forgive me for not comparing various Spit marks, but there are folks on this board who know more about Spits than I do.

This almost seems to follow a general trend with Japanese manufacture throughout the war. Early on their engines, rifles, and equipment were put together rather well. But the later you go, the less reliable and more cantankerous they become. Call me crazy (I expect someone to) but the History Channel had a nifty special about Japanese guns of WW2. Early on, they produced some awfully fine rifles. But one look at the late-war production and you'd flinch. They also said Japan had a habit of drafting their machinists and other skilled workers into the military. Hence the films you see of kids making rifle bolts and the like. Compare that to the skilled folks, and the high level of training of new hires, in P&W or Wright factories and its apples to oranges.



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Flakbait [Delta6]

[HoHun]

Hi Kweassa,

>Some people consider that the A6M was an accident, or a "freak of nature", but however, if the plans for the A6M didn't just drop out of the sky, from a 1940 perspective the A6M2 was one of the fastest fighters in the world.

According to Informational Intelligence Summary No. 85, the A6M2 tested by the US Navy topped out at just 524 km/h @ 4880 m or 434 km/h @ sea level.

Here's a comparison sorted by sea level speed:

P-39D:      571 km/h @ 3960 m, 484 km/h @ sea level
P-40E:      559 km/h @ 3880 m, 484 km/h @ sea level
Spitfire I: 571 km/h @ 5000 m, 487 km/h @ sea level
Me 109E-4:  584 km/h @ 5000 m, 480 km/h @ sea level
F4F-4:      515 km/h @ 5730 m, 457 km/h @ sea level
A6M2:       524 km/h @ 4880 m, 434 km/h @ sea level

I'm not sure about the Hurricane I and the Me 110C-4/B, but I'd say they should both as fast as the A6M2 or a bit faster depending on altitude.

Regards,

Henning (HoHun)

[GScholz]

The Bf110C-4 would actually be the fastest of the bunch.

[HoHun]

Hi Flakbait,

>Isegrim, engine type (radial vs inline) could be debated ad nauseum. The P-47M could hit nearly 500mph, and used a radial engine four feet across to do it. The B-29 had four of THE biggest (3,350 cubic inch, 5 feet across) radials out there, and did more than any other bomber could.

Well, in fact the debate is somewhat academic as both radial and inline engines finally evolved into quite similar three-dimensional engines, so they both have to be considered interim types :-) Note that V engines aren't strictly inline, anyway, nor are twin-row radials strictly radial.

The point about the A6M's radial is simply that it has about the same power as the DB601A, and less than the Merlin III, while being an air-cooled radial with a big drag penalty compared to a liquid-cooled V engine of the same output.

Regards,

Henning (HoHun)

[F4UDOA]

Hohun,

The A6M2 in that report was faster than the F4F-4 at sea level and outclimbed the P-38F to almost 15,000FT.

So take the listed performance as being a little generous.