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General Forums => Aircraft and Vehicles => Topic started by: Kweassa on November 08, 2004, 08:31:13 AM

Title: Why are the Japanese planes so slow?
Post by: Kweassa on November 08, 2004, 08:31:13 AM

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?

Title: Why are the Japanese planes so slow?
Post by: Furball on November 08, 2004, 08:40:07 AM

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

Title: Why are the Japanese planes so slow?
Post by: eddiek on November 08, 2004, 08:49:34 AM

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.

Title: Why are the Japanese planes so slow?
Post by: Angus on November 08, 2004, 08:50:33 AM

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....

Title: Why are the Japanese planes so slow?
Post by: GScholz on November 08, 2004, 09:13:27 AM

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.

Title: Why are the Japanese planes so slow?
Post by: VO101_Isegrim on November 08, 2004, 09:54:06 AM

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...

Title: Why are the Japanese planes so slow?
Post by: humble on November 08, 2004, 10:28:43 AM

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:).....

Title: Why are the Japanese planes so slow?
Post by: GScholz on November 08, 2004, 10:39:33 AM

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.

Title: Why are the Japanese planes so slow?
Post by: Angus on November 08, 2004, 12:03:27 PM

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.

Title: Why are the Japanese planes so slow?
Post by: humble on November 08, 2004, 12:35:46 PM

Quote

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....

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 08, 2004, 12:48:45 PM

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]
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Title: Re: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 01:25:13 PM

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)

Title: Why are the Japanese planes so slow?
Post by: GScholz on November 08, 2004, 01:29:06 PM

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

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 01:36:15 PM

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)

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 08, 2004, 02:39:47 PM

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.

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 03:04:40 PM

Hi F4UDOA,

>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.

The listed performance for which aircraft?

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 08, 2004, 03:41:52 PM

Hohun,

Well based on that report

1. The F4F-4 should have been faster at sea level according to listed performance.
2. The P-38F should have out climbed the A6M2 at low alt.
3. The P-39 as tested was overboosted to 70" MAP and then lowered to 54"MAP. These settings are well above it's normal ratings. Also the Zero overtook t in speed at moderate altitudes and was faster at alt. This is also contrary to stated P-39 performance.

The A6M5 test is most interesting to me. The speeds of the F6F, F4U, P-38L, P-47D as tested are really interesting.

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 04:00:18 PM

Hi F4UDOA,

>1. The F4F-4 should have been faster at sea level according to listed performance.

I've listed the USN speeds in my comparison. If something was wrong, it must have been with the F4F-4 as the recorded A6M2 speeds show it being slower than a properly operating F4F-4.

>3. The P-39 as tested was overboosted to 70" MAP and then lowered to 54"MAP. These settings are well above it's normal ratings.

Well, it seems to have been a cowboy style comparison :-) But the Navy figures for the A6M2 look realistic anyway.

(The RAF speed test figures I quoted are for 2950 rpm, 42" Hg. The comparison used 70" Hg, 52" Hg and 55" Hg. It might well be that the USAAF operationally used higher pressures than the 42" Hg indicated by the RAF report, but these were only available at low altitudes of course.)

>Also the Zero overtook t in speed at moderate altitudes and was faster at alt. This is also contrary to stated P-39 performance.

Actually, the report shows that the P-39 was faster at all altitudes though the A6M2 at some altitudes at the better initial acceleration from cruise speed.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 08, 2004, 04:03:02 PM

Quote

Originally posted by HoHun
Hi Flakbait,

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)

What they evolved into really isn't relavent, as WW2 aircraft either had a skinny, sleak cowling indicating a hot-water motor, or a very round one indicating a radial. And it is a rather moot point regarding the A6M engine being radial since it hit nearly the same speeds as some of the hot-water, 12 cylinder engines with slightly higher HP ratings. Isegrim said radials had higher drag; true, but that higher drag is hardly enough to cause a massive discrepency between a radial fighter and a hot-water fighter. Look at the difference between the P-51H and the P-47M; it's only 17mph (487mph vs 470mph). Look at the difference between the A6M3 and Bf-109E4; 9mph with a 45 hp differential between the two. Everyone knows the Sake 12 (later 21) engine had less hp than nearly every radial and most hot-water 12s. Besides, I posted that info. The most power any Sake-series engine produced regularly was 1,130 hp. Roughly the same as early Alison or DB engines. The kicker is it couldn't crank out any more hp and the more powerful engine designs were held up by bombing, material shortages, or the fact Japanese labor quality stunk by January of '44.

The Japanese military had a nasty practice of drafting any man fit to hold a rifle. This meant people who ordinarily worked on machine tools were stuck in the mud with a gun. What's worse, as the war went on Japan had fewer and fewer people trained in how to work metal to exacting tolerances. How can you expect to get 1,500 hp out of an engine if the cylinder barrels are 0.2" out of round and the valves don't meet spec? You won't. As for why Japanese fighters were so slow when compared to everything else, it could be shoddy workmanship, bad design, faulty carbs, fuel pump glitches or any number of other reasons.



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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 04:10:01 PM

Hi Flakbait,

>And it is a rather moot point regarding the A6M engine being radial since it hit nearly the same speeds as some of the hot-water, 12 cylinder engines with slightly higher HP ratings.

Actually, it didn't even come close:

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
A6M2:       524 km/h @ 4880 m, 434 km/h @ sea level

Quite obviously, the higher drag of the radial engine was at least partially responsible for that.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 08, 2004, 04:19:39 PM

Quote

Originally posted by HoHun
Hi Flakbait,

>And it is a rather moot point regarding the A6M engine being radial since it hit nearly the same speeds as some of the hot-water, 12 cylinder engines with slightly higher HP ratings.

Actually, it didn't even come close:

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
A6M2:       524 km/h @ 4880 m, 434 km/h @ sea level

Quite obviously, the higher drag of the radial engine was at least partially responsible for that.

Regards,

Henning (HoHun) [/B]

You're ignoring something. The A6M2 had an engine with a max rating of 950hp, which means its giving up 225hp to the 109E4. That's a lot more than just radial engine drag. Take the A6M3 Sake 21 engine which produced 1,130hp, and the differential is only 45hp and 9mph. If you upped the Sake 21 to match the 1,175hp the DB601 pumped out, the difference would probably be 5-7mph and most likely related more to overall airframe design than just engine drag.



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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: HoHun on November 08, 2004, 04:44:10 PM

Hi Flakbait,

>You're ignoring something.

Actually, I think you're overestimating the power of the DB601A-1. It had a maximum emergency rating of 1050 HP, so it's not that far off the 950 HP you're using.

I was using 1000 HP for the Sakai 12, so if it was 950 HP that helps to bridge the gap. (Do you have a good source for that engine's power chart?)

Using the 30 min power for the DB601A-1, which gave 970 HP maximum, the Me 109E-4 still got 465 km/h @ sea level, compared to the Zero's 431 km/h.

>Take the A6M3 Sake 21 engine which produced 1,130hp, and the differential is only 45hp and 9mph. If you upped the Sake 21 to match the 1,175hp the DB601 pumped out, the difference would probably be 5-7mph and most likely related more to overall airframe design than just engine drag.

Well, you're right that in comparison to the Me 109, it's not all engine drag.

If I use the Spitfire I as reference point and reduce its power to 950 HP artificially, guessing the sea level as somewhat below that, I get 448 km/h @ sea level. That's for an airframe with a very similar (actually slightly larger) wing area. It's still 27 km/h faster than the Zero at the same power, and most of that can safely be attributed to the radial engine's drag.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 08, 2004, 05:13:45 PM

I'm using a hoge-podge of references because I'm lacking in German and Japanese aircraft books. Mostly Baugher's site (Aircraft of the World), J-Aircraft and Aircraft of WW2 (real thin book). AC of WW2 gives the 109E4 using a DB601Aa engine at 1,175hp while Baugher, AC of WW2 and J-Aircraft have the A6M2 pushing out 940-950hp at takeoff. The A6M3 data from J-Aircraft and Baugher gives 1,130hp from the Sake 21. Hence the reason I chose to compare the 1,175hp DB601Aa with the 1,130hp Sake 21. I really wish I had good power vs alt charts for the Sake and Db engine series, but unfortunately I don't. Still, no matter which way you cut it, the difference in speed between a radial engine and a hot-water 12 of similar power isn't much. Not nearly enough to account for the huge speed discrepancy of Japanese fighters after 1942, anyway.

Here's some links to chew on...

http://www.j-aircraft.com/research/zerofacts.htm
http://www.csd.uwo.ca/~pettypi/elevon/baugher_other/


But back to the original question (sorry for the temp hijack, Kweassa)... how come Japanese aircraft were so danged slow? Bad data, bad engines, crummy workforce or just a lack of innovation? After all, once the Sake 21 came around the Japanese used it on every A6M mark that saw combat and didn't change much of anything until mid '44. The DB601A copy on the Hien was a notorious beast to maintain that rarely put out the same hp twice. The Ha45 engine I don't know too much about. Maybe Busa could chime in on that?


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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: Pongo on November 08, 2004, 05:25:19 PM

The Japanese learned the wrong lesson from their overwhelming success in early  1942.

The western powers learned some of the right lessons from thier failures and successes in 1939-41.

The Americans were just about ready to unleash the results of those lessons. The Japanese faltered on what they wanted and by the time they started to have more modern ideas about what a fighter should be it was too late.
But even then. Planes with good modern deisgn qualities like the Raiden where not looked on favourably even in 1944.

victory disease. (why did the germans invade russia with tanks with 50mm guns?)

counter productive fighter pilot culture

very poor country, seriosly overmatched by her enemies.

The US and Brits could afford to make some huge mistakes in aircraft developement and procurment. The Japanese could not.

Title: Why are the Japanese planes so slow?
Post by: NobAkimoto on November 09, 2004, 01:57:32 AM

I think it was probably expressed best in the counterfactual series of novels "Super Carrier Yamato"(in case anyone's interested, yeah it's a crazy series of books where Yamato is laid down as an angled deck super carrier...but nevermind about that) when staff officer remarks about how the F8F is eating the newly introduced A7M for breakfast.

"Our engines are at least a decade behind the West, and we simply can't produce them at a high enough quality." Examples of underpowered engines like the Homare 22(NK9K) being used in aircraft intended for service past 1942 by the Navy AGAINST the wishes of aircraft designers shows both a reluctance to move towards heavy designs and perhaps just as importantly an inability to adequately produce these things in quantities where they're going to be making a difference.

I mean let's just compare theoritical 1945 designs between the USN and IJN here.

A7M2-
MK9A Radial 2200hp at takeoff/1800hp 20,000 ft.
Performance: Max Speed- 390mph@21,655ft

F4U-4
R-2800-42W war emergency power 2760hp
Performance: Max Speed- 446mph

F8F-1
R-2800-34W 2100hp at altitude
Performance: Max Speed- 434mph

Any other difference?

Quality of aircraft fuel definitely has something to do with it. American fuel was certainly far better and Japanese industry never came close to reproducing it.

Dunno, probably given equal quality engines and fuel you'd see more competitive Japanese designs, but they had jack **** to work with to begin with and even less to work with as the war dragged on. The A6M itself was a bit of a compromise made by a nation which didn't have the highest quality engines available.

Title: Why are the Japanese planes so slow?
Post by: Karnak on November 09, 2004, 10:30:41 AM

I don't agree that their engines, as described on paper, were too far behind to break 400mph.  The Ki-46 at the start of the war was already doing 386mph.

If the engine on the Ki-84 was actually putting out 1,650hp at 21,000ft it would be doing better than 400mph.

The Spitfire Mk XIV did 448mph with a 2,050hp engine.  You don't need monster 2,750hp engines to break 400mph.


The options I see are as follows:

1) Japanese engines did not produce nearly the claimed power.

2) Japanese fuel was even worse than is generally thought.

3) Japanese fighters were faster than is noted in surviving records but supporting documentation did not survive or never existed.

4) Allied aircraft and German aircraft were slower than the official speed documents claim.  For example I recall reading that the He219 never broke 400mph level flight in service despite the official speed being 416mph.


Certainly it could be more than one of these things and certainly Japanese aircraft were more adversely affected than others.  However I cannot see a change in fuel taking the Ki-84 from 388mph to 427mph and American comments about the P-51H being slightly faster do not at all match the 323mph at sea level and 388mph at best altitude Ki-84.

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 09, 2004, 10:46:19 AM

Karnak,

I think there are two factors contributing to the disparity of performance between the KI-84 and P-51H.

1. An overstatement of performance of the P-51H.
2. The high octane fuel use by the AAF in the testing of the Ki-84.

The truth lies somewhere in between.

Title: Why are the Japanese planes so slow?
Post by: MiloMorai on November 09, 2004, 10:48:04 AM

Quote

Originally posted by Karnak
For example I recall reading that the He219 never broke 400mph level flight in service despite the official speed being 416mph.

And that was with a 'cleaned up' a/c that had some guns removed, antenna removed and exhaust shrouds removed.

Title: Why are the Japanese planes so slow?
Post by: Karnak on November 09, 2004, 10:52:05 AM

Quote

Originally posted by F4UDOA
Karnak,

I think there are two factors contributing to the disparity of performance between the KI-84 and P-51H.

1. An overstatement of performance of the P-51H.
2. The high octane fuel use by the AAF in the testing of the Ki-84.

The truth lies somewhere in between.

That is the feeling I get too and it is leading me to wonder how many other aircraft had overstated performance numbers published, or how many only obtained the published numbers under ideal circumstances that service aircraft would never have obtained.  If that were true a lot of things I've been looking at would start to make sense and not just for Japanese aircraft.

Title: A few points
Post by: joeblogs on November 09, 2004, 11:50:25 AM

First, the Japanese built (in large numbers) many good radial engines up to about 1200 HP. Most of these were derivatives of western designs licensed from the U.S. & U.K. in the early 1930s. The engines were reliable and the pilots trained to operate them at extremely lean fuel mixtures (hence the remarkably long range in some extraordinary missions in 1941).

Second, the Japanese did not devote much resources to two-stage superchargers until the war was already on. This was due in part to a lack of interest in high-altitude interceptors.

To my knowledge, Pratt & Whitney was the first to put a two stage supercharger on a production engine and it took several years to make them reliable. But P&W had already been experimenting with these for several years prior to the war.

Third, U.S. engine makers made the jump to larger, two row radial engines before the war began. Wright had the reliable 2,600 and P&W got the R2800 into production remarkably fast for the typical gestation period of piston engines. Wright was not so fortunate with the R3350, which was also in development well before the war. The Japanese were nowhere as far along and did not have the option of licensing designs after its relations with the west soured.

Fourth, Japanese manufacturers were operating flat out in order to produce existing designs for the airforce and navy. They did not have adequate resources to simultaneusly develop new engines. In other words, The Japanese industry could not scale up as the U.S. industry did.

BTW there is a similar tale for Italy.

-blogs

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 09, 2004, 12:06:18 PM

JoeB.

I didn't realize your were a Philly guy.

I am in Cherry Hill now, Grew up around George Washington High.

Or maybe we talked about this already and I forgot.

Anyway
Go Birds!

Title: F4UDOA
Post by: joeblogs on November 09, 2004, 12:14:44 PM

Yes, we are pretty darn close.

-Blogs

Quote

Originally posted by F4UDOA
JoeB.

I didn't realize your were a Philly guy.

I am in Cherry Hill now, Grew up around George Washington High.

Or maybe we talked about this already and I forgot.

Anyway
Go Birds!

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 09, 2004, 12:33:21 PM

It may have been fuel, differing documentation and engine ratings, Karnak. We know they had 87 octane fuel, but fuel with higher octane ratings is rarely if ever mentioned. High octane fuel is needed if you want to hit high speeds with any piston engine. The higher the octane rating, and the greater refinement done, the harder you can push the engine.

As for engine rating and actual power, Baugher has a tid-bit about this on his page regarding the A7M Reppu.

Quote

The A7M1 prototype flew for the first time on May 6, 1944, test pilot Eisaku Shibamaya being at the controls. Test pilots reported that the A7M1 handled extremely well, and that the use of the combat flaps made the A7M1 just as maneuverable as the Zero. However, they also reported that the aircraft was significantly underpowered for its weight. The Homare 22 delivered only 1300 hp at 19,685 against a calculated rating of 1700 hp, and at this altitude maximum speed was only about 350 mph. In retrospect, Horikoshi was right. Because of its disappointing high-altitude performance, on July 30, 1944 the Navy ordered that further work on the A7M1 be suspended after the second prototype had been built.

I got that info from over here (http://www.csd.uwo.ca/~pettypi/elevon/baugher_other/a7mbau.html). If one engine wasn't producing its rated power at a given altitude, others could've had the same problem to a lesser degree. We know the Ha40 and Ha140 engines (copies of the DB601) were notorious for rarely putting out their rated power. But I doubt all of them had this problem. The Sake 12 and Sake 21 engines (copies of the P&W R-1830) worked flawlessly and delivered their rated power on demand. The most plausable explination is Japanese aircraft were faster than documentation gives them credit for. An easy way to check the speed differential between fuels would be to take a look at test reports of a given aircraft using different octane rated fuels. If the F4U was tested with 87, 110 and 120 octane fuels a quick comparison between top speeds would let anyone see how much speed is gained from using a given type of fuel.



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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: Karnak on November 09, 2004, 12:38:38 PM

I cannot see how going from 87 octane to 100 octane on an engine designed for 94 octane would yield a 39mph speed gain.

Some gain certainly, maybe even 20 or 25mph.  Not 39mph.

Maybe if the Japanese fuel was more in the 80 octane range.

Title: Why are the Japanese planes so slow?
Post by: Angus on November 09, 2004, 01:01:40 PM

Karnak:
I think you are right there.
However, the climb numbers would show this better, that's usually the case by boosting up.
Are there any around?

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 09, 2004, 01:34:41 PM

Hi Flakbait,

>AC of WW2 gives the 109E4 using a DB601Aa engine at 1,175hp while Baugher, AC of WW2 and J-Aircraft have the A6M2 pushing out 940-950hp at takeoff.

Roger. That DB601Aa is somewhat of a mystery to me, some good experts claimed it wasn't ever used in the Emil, but a recently recovered Me 109E from Russia clearly has one.

The Battle-of-Britain Me 109E-4 had the DB601A-1 in the 4.5 km full throttle height variant, though, and it didn't get more than 1050 HP. Though often higher take-off ratings are listed for the DB601A-1, they actually are for a 60 s rating (enforced by a mechanical clockwork) that apparently didn't make it into service at all.

>The A6M3 data from J-Aircraft and Baugher gives 1,130hp from the Sake 21. Hence the reason I chose to compare the 1,175hp DB601Aa with the 1,130hp Sake 21.

I see. Going from 940 HP at sea level to 1130 HP would have boosted the A6M2 from 434 km/h to 461 km/h. That's still some way below the Me 109E-4's 480 km/h, and now it's the Emil that has less power. (Speed only increases by the cubic root of power, so you have to add a lot of power to get a worthwhile speed increase.)

>Still, no matter which way you cut it, the difference in speed between a radial engine and a hot-water 12 of similar power isn't much. Not nearly enough to account for the huge speed discrepancy of Japanese fighters after 1942, anyway.

Well, looking at the A6M2 alone, the difference was bad enough in a 1940 comparison. I think we both agree that there's not much need to discuss the Zero in the context of the original question, though, as it pretty much stagnated at a low power level.

The mid-war to late-war engines were better, and I'd agree that at least at a first glance, the Japanese aircraft weren't all power-handicapped.

Looking at the different Japanese designs, the sequence Ki-27 - Ki-43 - Ki-44 - Ki-84 seems to be especially interesting.

The Ki-27 was a very manoeuvrable aircraft, but the Ki-43 was built for performance already and almost failing the acceptance tests as a result. Still, by western standards, it was under-powered and extremely manoeuvrable. If you look closely at the Ki-84, you'll notice that it is very similar in size and shape to the Ki-43, and to me it looks like Nakajima designed the same aircraft once more, but with a much more powerful engine.

The Ki-44, on the other hand, stands out from the others in that set. It has a much smaller wing - smaller than an Emil's, actually, is very light - hardly heavier than the Emil - and yet features a 1500+ HP engine. That's a pretty unique combination - you could consider it a pocket Lavochkin ;-)

Still, even the Ki-44-II tops at 616 km/h @ 5030 m. The low altitude makes this absolute top speed seem relatively low, but at sea level, the Ki-44-II does 542 km/h which is better than the Me 109G-2 and not that far from the Fw 190A-5. In terms of climb rate, the Ki-44-II was spectacular.

It was the lack of a decent high-altitude supercharger that deprived the Ki-44 of a good top speed. I'm not sure about the reason - it may be that they were lacking two-stage superchargers, but on the other hand, the German aircraft didn't use these either and didn't fall behind that badly anyway. Maybe it was a question of a badly chosen design point - but on the other hand, why choose a design point for an interceptor that doesn't result in optimum performance at the level where the bombers are to be expected?

I'm a bit at a loss here.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: Karnak on November 09, 2004, 01:50:04 PM

I'd like to have a Ki-44-II-Otsu is AH.


I do like the Ki-84, I was just expecting a bit more speed and a bit better high speed handling.

Title: Why are the Japanese planes so slow?
Post by: Angus on November 09, 2004, 02:43:16 PM

Ki44...what nickname again?

Anyway, from HoHun
"It was the lack of a decent high-altitude supercharger that deprived the Ki-44 of a good top speed. I'm not sure about the reason - it may be that they were lacking two-stage superchargers, but on the other hand, the German aircraft didn't use these either and didn't fall behind that badly anyway."

I tend to disagree with this point.
From the Merlin 61 onwards for almost 2 years, the Germans were indeed completely inferior in the very high altitude department.

Title: Why are the Japanese planes so slow?
Post by: Karnak on November 09, 2004, 02:55:39 PM

Ki-44 is Tojo

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 09, 2004, 03:11:08 PM

HoHun, look closely:

A6M2    950hp    331mph
A6M3    1,130hp 338mph

The A6M2 tops out at 331mph, the A6M3 tops out at 338mph and has clipped tips. I'm not comparing aircraft based on the year they were made, I'm comparing them based on engine power and top speed. Though even with clipped tips the A6M3 wasn't faster than the Emil. Hell, it was 9mph slower at altitude. Still, after mid 1942 the A6M design was completely outclassed by other aircraft both from an engine output standpoint and an aerodynamic standpoint. From there on it was no different than the Bf-109 or the Ki-43; too much weight, not enough engine, and terrible controls at high speed.

The Ki-44 is a rather promising aircraft and an absolute rocket in a climb. When production started in 1942 it could hold its own at 376mph, and was definitely an excellent design. What makes me think, though, is the fact that Baugher says "It was made obsolete by the Ki-84." If the Ki-44-III was made obsolete by the Ki-84, how come the Ki-84 in AH has lead elevators and is only 14mph faster? That's not obsolete, that's a close call and a narrower gap than many other fighters. Either someone in Japan made a bad call or the Hayate was a lot better than the paperwork gives it credit for. If the Tojo had a turbo, or even a double deuce (two speed two stage super) that would've brought up the top speed at altitude and maybe increased the critical alt. Who knows why it was never fitted with one of these. The Japanese did have two-speed supers and used them fairly regularly. But it doesn't look like they used a double deuce except on a few experimental types. The same goes for their turbos.

The Ki-43 was a joke by 1942 since nearly anything in the Pacific could outrun it at will. Only at very low speeds, where the Oscar was a dragster in acceleration, could it beat an opponent. Otherwise it was too flimsy, underpowered and undergunned.

The Ki-61 was, at best, an interesting experiment and a learning experience. The Ki-100 was better, roughly on par with the Tojo in terms of maneuvering, speed and firepower though nowhere near as fast a climber.

The Ki-84 looks like the big brother of the Oscar, and both look like they share the same wing. If it really did have excellent maneuverability and could hit 427mph, most aircraft would be hard pressed to match it. The high speed would also make the Ki-84 the best Japanese fighter of the war.


Regarding Japanese fuel, does anyone know the octane ratings of fuel produced by the Japanese? As best I can figure it, 87 looks like the most common stuff they made. Could it be that Japan was in a similar boat as Germany in making high-test AV gas?


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Flakbait [Delta6]
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Title: engine rating and octane
Post by: joeblogs on November 09, 2004, 03:54:04 PM

Problem is that we don't know the Japanese engines can go up in octane. Once you get into the high lead ranges, valves & bearings have to made of different materials.

In the (limited) data I have on Japanese engines, none are rated at an octane number above 92. What's more, none generate more than 700HP at 19,000 feet.

Correction: The Sakae 21 develops 1,150 HP at sea level and 950 HP at 19,700 feet at military power.

-Blogs

Quote

Originally posted by flakbait
.... An easy way to check the speed differential between fuels would be to take a look at test reports of a given aircraft using different octane rated fuels. If the F4U was tested with 87, 110 and 120 octane fuels a quick comparison between top speeds would let anyone see how much speed is gained from using a given type of fuel.



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Flakbait [Delta6]
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Title: Re: F4UDOA
Post by: Oldman731 on November 09, 2004, 04:07:02 PM

Quote

Originally posted by joeblogs
Yes, we are pretty darn close.

-Blogs

Yah.  Me, too.

- oldman

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 09, 2004, 04:40:11 PM

Actually the reason I asked was so we could try to reverse-calculate the Ki-84 speed. If the TAIC test used 120 octane fuel, and the Hayate normally used 92, maybe another aircraft has a set of numbers from two different fuels. Granted it wouldn't be perfect, or exact, but it would be a rough guess as far as the actual top speed. Hence my example of the F4U; if it had numbers from two different fuels, the speed difference could be used to roughly SWAG the Ki-84 speed difference between the TAIC test and the actual top speed.



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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: HoHun on November 09, 2004, 05:01:47 PM

Hi Flakbait,

>Still, after mid 1942 the A6M design was completely outclassed by other aircraft both from an engine output standpoint and an aerodynamic standpoint.

I absolutely agree.

>What makes me think, though, is the fact that Baugher says "It was made obsolete by the Ki-84." If the Ki-44-III was made obsolete by the Ki-84, how come the Ki-84 in AH has lead elevators and is only 14mph faster?

Well, the Ki-84 seems to have been plagued by engine trouble at least initially, and I've read that some Japanese pilots didn't consider it a progress over the Ki-44.

The Ki-84, however, seems to have been a leap forward in terms of ease of fabrication, requiring only 56% of the resources per airframe the Ki-43 did (and I'd think that the relation to the Ki-44 was similar).

The lead elevators seem to be based on a complaint about the first series production Ki-84 - no idea whether that was corrected later.

>But it doesn't look like they used a double deuce except on a few experimental types. The same goes for their turbos.

Roger. That was hi tech at that time, and in fact, the Germans didn't have many of these either.

>The Ki-43 was a joke by 1942 since nearly anything in the Pacific could outrun it at will.

As I understand it, it had to be kept in production for lack of high-performance engines. Tough, but even the US kept producing the outdated FM-2 and P-40 without even being as desperate as the Japanese.

>The Ki-61 was, at best, an interesting experiment and a learning experience. The Ki-100 was better, roughly on par with the Tojo in terms of maneuvering, speed and firepower though nowhere near as fast a climber.

The Ki-61 actually was a development based on the Heinkel He 100. The ancestry is a bit of a mystery still since Heinkel sold the plans and a production  licence to the Imperial Navy, not the Army, but the contemporary Kawasaki designs show a distinct Heinkel influence on some other points - like surface condensation cooling - as well. The earlier Ki-60 seems to have closer to the Heinkel than the Ki-61, which underwent an extensive redesign, primarily to improve range.

I'm not sure what to think about the Ki-61 performance. It was pretty good for a DB601A-1-engined aircraft, but I'm not sure it was ever improved on since the more poweful versions of that engine appear to have been prohibitively troublesome.

With regard to the Ki-100, I'm not sure about the exact performance.

>Regarding Japanese fuel, does anyone know the octane ratings of fuel produced by the Japanese? As best I can figure it, 87 looks like the most common stuff they made. Could it be that Japan was in a similar boat as Germany in making high-test AV gas?

The German C3 actually was pretty much comparable to 100/130 grade US fuel. I believe Robert Mikesh mentions that the Japanese were limited to 92 octane maximum, but that came from one oil field only and apparently was in limited supply towards the end of the war, or maybe the oil field was actually lost. I've read the Navy got hold of most of that fuel, probably because they ran the tankers, and only little of it reached the Army units. Water injection might have made up for some loss of octane, though.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 10, 2004, 07:06:14 AM

From what Baugher said the lead elevators were corrected when the airframe underwent changes between the pre-production and the full production model. Its also where the jet-thrust exhaust stacks came in, along with a host of other changes and improvements. All told the Ki-84, both to the eye and on paper, looks like the mother of all Japanese fighters. Definitely something to be reckoned with!

The Ki-61 was supposed to get a redesigned engine (Ha-140) for the Ki-61-II model, but it was a nightmare to keep running. Between crank failures, main bearing failures, and cooling system hiccups it was enough to give anyone a fit. On the rare occasion when it did run properly, it had 14mph more speed than the KAIc and a much faster climb rate. Though I remember a Smithsonian tech saying, while he was rebuilding a DB605, that the Germans managed to get it just right. Three degrees more inclination of piston angle would've broken the crank, two degrees less inclination and it would've siezed up. If the Japanese changed the crank angles up it would explain some of the crankshaft failures they had. The rest could be traced to badly skilled workers in the engine factory... before it was bombed (bad omen maybe? :D)

As best I can tell, the Ki-100 was a bit quicker to accelerate than the Ki-61 KAIc and a better climber thanks to an extra 400+ horses. Otherwise the two were pretty close from a performance point of view. The Ki-100 and Ki-61-II with an Ha-140 motor are almost twins performance-wise; the Ki-100 being 20mph slower is the only real diff. Baugher's joint (bottom link posted earlier) has the spec for it and quite a few other Japanese fighters.

What really makes me rack my brain is Japanese engines semed almost hit or miss. The Sake 21 worked very well, the Ha-22 was 500hp below spec, the Ha40 and Ha140 both had trouble staying in one piece and rarely delivered full rated power, the Ha45 had teething troubles but eventually worked just fine. The Ha33 on the Ki-100 was a proven and very reliable 1,500hp motor, even the Mk9A radial at 2,200hp was a proven design. Why not use one of the more proven engines instead of tinkering with an inverted V or keeping failed engine designs around?



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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: MiloMorai on November 10, 2004, 07:28:31 AM

flakbait,

 can you explain what you mean by 'inclination of piston angle'?

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 10, 2004, 08:17:09 AM

Quote

Actually the reason I asked was so we could try to reverse-calculate the Ki-84 speed. If the TAIC test used 120 octane fuel, and the Hayate normally used 92, maybe another aircraft has a set of numbers from two different fuels. Granted it wouldn't be perfect, or exact, but it would be a rough guess as far as the actual top speed. Hence my example of the F4U; if it had numbers from two different fuels, the speed difference could be used to roughly SWAG the Ki-84 speed difference between the TAIC test and the actual top speed.

Actually Flakbait that is really easy to do without the use of different fuels. Since the use of higher octance fuel only allowed for increased power by incresed allowable manifold pressure you can look at the F4U at three differrent MAP's, Normal, Mil and Combat powers.

What was the highest MAP the KI-84 could run at on 92 octane fuel? What did MAP did it use at 120 octane? If you know the differance there you can apply that to the F4U-1D.

At 60"MAP at sea level it could reach 358MPH (With pylons attached). At 44" MAP (normal power) it could only reach 320MPH. There is 48MPH difference on 16" of MAP. Granted that is also a difference between 1675HP and 2250HP.

If you know the difference in MAP with the KI-84 you should get an idea of the HP gain with higher octane fuel. Based on the F4U-1D I would say the difference is very significant. Enough to account for 30MPH at least.

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 10, 2004, 09:35:47 AM

Quote

Originally posted by F4UDOA
Actually Flakbait that is really easy to do without the use of different fuels. Since the use of higher octance fuel only allowed for increased power by incresed allowable manifold pressure you can look at the F4U at three differrent MAP's, Normal, Mil and Combat powers.

What was the highest MAP the KI-84 could run at on 92 octane fuel? What did MAP did it use at 120 octane? If you know the differance there you can apply that to the F4U-1D.

At 60"MAP at sea level it could reach 358MPH (With pylons attached). At 44" MAP (normal power) it could only reach 320MPH. There is 48MPH difference on 16" of MAP. Granted that is also a difference between 1675HP and 2250HP.

If you know the difference in MAP with the KI-84 you should get an idea of the HP gain with higher octane fuel. Based on the F4U-1D I would say the difference is very significant. Enough to account for 30MPH at least.

DOA, reverse it. I didn't mean to say that I wanted to compare the Ki-84 to the F4U, I wanted to compare the speed difference of the F4U using different fuels to the Ki-84 performance in the TAIC test. Unfortunately, I can't find a copy of the TAIC report to get the MAP numbers they used. What's worse, you can't use the MAP and HP difference between standard running pressures (MIL, normal, cruise) with 92Oc fuel to figure a MAP and HP rise on a higher octane fuel. The numbers would be entirely different on 110Oc than 92Oc, with a different spread. So reverse-engineering the numbers from 110Oc (TAIC test) to 92Oc (Japanese gas) is nigh on impossible. Unless of course I'm way off and the MAP numbers simply rise in lock-step from one octane to another.

We know the Ki-84 in AH pulls +250mm (38.92"Hg) and puts out 1,800hp at takeoff. But Busa and several others have mentioned +350mm (42.92"Hg) for the pre-production machines as the MAP limit. Why this odd 4"Hg difference? Limiting an engine by 4"Hg doesn't make any sense, unless a different gearing for the super or another carb was used.

Ok, now I know what Kweassa felt like when trying to fathom prop problems. Brb, need Tylenol!


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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 10, 2004, 12:30:11 PM

Flakbait,

I wasn't comparing the two.

Just showing that the difference on the F4U-1D from 44"MAP to 60 " MAP is 38MPH.

It doesn't matter if the KI-84 is using 92 octane or 120 octane fuel unless you are at maximum MAP. At normal power in any aircraft the fuel octane will not affect performance to any great degree and less than max power. Octane only affects performance at max power by preventing premature detonation and allowing for higher MAP. An F4U with 100 octane fuel is just as fast as one with 120 octane fuel at normal or mil power.

So if you look at the HP increase in the F4U from 44" to 60" you can see it increases HP from 1675HP to 2250HP and increase of almost 35%. If you know what MAP the KI-84 was running at 120 octane then you can reverse engineer the HP and probable speed increase.

Title: Why are the Japanese planes so slow?
Post by: VO101_Isegrim on November 10, 2004, 01:39:44 PM

Quote

Originally posted by Angus
I tend to disagree with this point.
From the Merlin 61 onwards for almost 2 years, the Germans were indeed completely inferior in the very high altitude department.

Hardly. They had GM-1 in the first place, against which the two staged Merlins didnt stand a chance... German high alt fighters were exceeding 700 km/h in 1942, no Merlin engined Spitfire came even close to that. Thats the techspec part.... production is another matter. The British could never produce high alt fighters in any serious quantity, they always came too late, too few. For every high altitude Merlin 61 engined fighter of the RAF, the Luftwaffe fielded TEN high alt fighters with equal or better performance... so you are wrong both technically and factually.

Title: Why are the Japanese planes so slow?
Post by: Karnak on November 10, 2004, 01:47:44 PM

Barbi,

Erm, which German high altitude fighters are you refering to?  I've never heard of any in 1942.  The first I know of is the Ta152, and yes, that one is a doozy.

However I know of nothing in 1942 that matches the Merlin 61 Spitfire F.Mk IX, or in 1943 that matches the Merlin 70 Spitfire HF.Mk IX, or anything in 1944 that matches the Griffon 65 Spitfire F.Mk XIV.

There is a reason the British built the Merlin 66 Spitfire LF.Mk IX and it was because the critical altitude of the German fighters was all in the medium altitude ranges and the Merlin 61 was too high.

Title: Why are the Japanese planes so slow?
Post by: flakbait on November 10, 2004, 01:56:48 PM

Quote

Originally posted by F4UDOA
Flakbait,

I wasn't comparing the two.

Just showing that the difference on the F4U-1D from 44"MAP to 60 " MAP is 38MPH.

It doesn't matter if the KI-84 is using 92 octane or 120 octane fuel unless you are at maximum MAP. At normal power in any aircraft the fuel octane will not affect performance to any great degree and less than max power. Octane only affects performance at max power by preventing premature detonation and allowing for higher MAP. An F4U with 100 octane fuel is just as fast as one with 120 octane fuel at normal or mil power.

So if you look at the HP increase in the F4U from 44" to 60" you can see it increases HP from 1675HP to 2250HP and increase of almost 35%. If you know what MAP the KI-84 was running at 120 octane then you can reverse engineer the HP and probable speed increase.

Ahhh, okay, now I see how its done. Now to track down a copy of that rotten report and see if they list the MAP it was pulling.

Thanks DOA!


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Flakbait [Delta6]
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Title: a qualification
Post by: joeblogs on November 10, 2004, 02:19:22 PM

One thing to note about this comparison - its should favor the Japanese plane.

Why? Because you'll be reading off the performance curve of the Japanese plane at or near its highest output. Of course the designers configure the plane taking into account the performance of the engine.

For the American plane, however, you would be reading off the performance curve well away from the full potential of the engine. As a result you will be inferring something about speeds for a bigger and heavier plane that was designed to be bigger and heavier because its engine had much more top end power.

-Blogs

Quote

Originally posted by flakbait
Ahhh, okay, now I see how its done. Now to track down a copy of that rotten report and see if they list the MAP it was pulling.

Thanks DOA!


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Flakbait [Delta6]
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Title: Why are the Japanese planes so slow?
Post by: Kurfürst on November 10, 2004, 02:29:41 PM

Quote

Originally posted by Karnak
Barbi,

Erm, which German high altitude fighters are you refering to?  I've never heard of any in 1942.  The first I know of is the Ta152, and yes, that one is a doozy.

[/B]

Karki,

so then you probably didnt hear about the Bf 109F-4/Z or the Bf 109G-1. The 109E-7/Z existed before that as well. And to leave the Germans, there was the Soviet MiG-3, too.

Quote

However I know of nothing in 1942 that matches the Merlin 61 Spitfire F.Mk IX,

[/B]

Hmm, actually the 109F-4 was faster, the 109G-1 was MUCH faster (over 700 km/h), the G-2/G-4 w/o any intercooler, any two stage cooler or other gimnick was just as fast. Not to mention, it was ten times as numerous in service...

Quote

or in 1943 that matches the Merlin 70 Spitfire HF.Mk IX,

[/B]

Again, 109F-4/Z, G-1, G-3, G-5, G-6/U2 etc. In fact the standard G-2 and G-4 wasnt that much off, maybe the HF Spit was some 10 km/h faster at altitude. And I mean the Spit HF IX, specially tuned for high alt performance, supposed to be the BEST high alt Spit at the time, which a mere 400 were built during the whole war, so I guess during 1943 maybe a dozen were built, pitted against the most ordinary fighter types the LW had.. WOW.

So in 42/43 the LW had thousends of 109Gs built/in service with very good high alt performance, the RAF had a handful of Mk IXs with about as good high alt performance, and 90% of the RAF was flying MkVs with waaaaaaaay inferior altitude performance to either the 109F or 109G..

I guess it wasnt the Jagdgruppes then that were concerned about finally getting some fighter with a comparable altitude performance to that of the enemy.. personally, I wouldnt be happy to meet a 109G at 8000m in a Spit MkV. Unfurtunately for me, chances are 9 to 1 that I will, I am flying in RAF colours in 1942, and for most of 1943.

Quote

or anything in 1944 that matches the Griffon 65 Spitfire F.Mk XIV.

[/B]

Hmm, Bf 109 G-5/U2/AS. :D If you include 1945 as well, I could say K-4s with the Doppellader, but even the rest of the AS or D engined 109s were quite close to it - and far, far more numerous, some 6500 being built. But frankly I doubt the Germans ever knew what a Spit XIV was, or that it even exists. I doubt that many British pilots knew. Again too late, too few. A mere five squadrons flying it, equivalent of single LW Gruppe... on the other side, the LW had very large number of high altitude 109s in service, which were again much faster at altitude than the common MkIXs of the RAF. Ironically, the LW had more Me 262 in the units than as many Mk XIV units the RAF had.. so I guess the LW had no real reason to be concerned about the high alt performance of it`s fighters... they had some allergic reactions, though, namely the Ta-152s, a fighter designed for a threat that never existed, but in the process it become a lot more than what was needed. Or what could be handled by the opposition`s HA fighters..

Quote

There is a reason the British built the Merlin 66 Spitfire LF.Mk IX and it was because the critical altitude of the German fighters was all in the medium altitude ranges and the Merlin 61 was too high. [/B]

There is much truth in that. The RAF developed the Mk IXF, with a much heavier and more complex engine and shorter range than the previous models, other parameters being sacrificed for good high alt performance. That was the first time they come up with something that could be compared to the German fighters in altitude performance. Then in 1943 they found out such rated altitude isnt required at all, there is no common operational use for it, there are no enemy flights at that altitude, and without a pressurized cocpit, the planes themselves are not fit for operating at such altitudes.. so they reverted back to medium altitude fighters, the LF Spits... the LW also toyed with two staged engines with intercoolers at the same time for the 109 (and you dont want to compare the Merlin 61 to the DB 628), and found out that the neccesary bulk and weight of the intercooler eats up most of the performance gain, its impractical most of the time, and for such specialized task, the optional GM-1 is a much more practical solution. Most fighters could compare with the best (and rare) types the enemy had, without maintaince and other problems, could be produced and sent to the front quickly and i quantities, and when really high performance was required, there were the high alt, GM-1 wielding units that simply dwarfed other high alt fighters. I find the German approach a lot more practical. And in 1944, they could improve the existing fighters very simply by adding a larger supercharger to the side of the existing engine, the /AS types were little more than that, really.

Title: Why are the Japanese planes so slow?
Post by: Angus on November 10, 2004, 02:49:00 PM

Oh, dear, Izzy at it again.

"Hmm, actually the 109F-4 was faster, the 109G-1 was MUCH faster (over 700 km/h), the G-2/G-4 w/o any intercooler, any two stage cooler or other gimnick was just as fast. Not to mention, it was ten times as numerous in service... "

At what altitides Izzy?
And where do you have these numbers from. Have NEVER seen them before.
So you're basically saying that the DB was so uber that it performed as well at (the same?) ceiling alt without any other aid such as second stage and so? And for your info, the intercooler was a necessary thing to cool the air between the two superchargers, but intercoolers also have the effect to increase power as a positive, and it's relatively simple.
Typical for lorries and tractors today is the beautiful combo Turbo-intercooler.

A question: How many were there of these 109G-1's. Interested, cos I never heard them mentioned before.
Could they cruise at 43K like the Merlin61 Spit IX, in battle formation, and were they in wing strengths like them?

Now bring some stuff for the dinnerplate Plz....

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 10, 2004, 03:06:29 PM

Achtung Luftwabbles,

This is a Japanese Army KI-84 thread. Go beat your weinershnitzle somewhere else.:rolleyes:

Title: Why are the Japanese planes so slow?
Post by: Angus on November 10, 2004, 03:12:13 PM

Hai, F4UDOA-san.

Title: Why are the Japanese planes so slow?
Post by: StarOfAfrica2 on November 10, 2004, 04:21:54 PM

I think that perhaps with all the technical information at our fingertips these days, even from as far back as 1940, maybe you gentlemen have overlooked a very important aspect of Japanese airplane development just before and during WWII.  Viewpoint.  

Japanese pilots (at least the IJN ones) came from a very small group of applicants.  Driven and determined to succeed, carefully screened and then put through some of the most rigorous and hellish training anyone can imagine, they were not just pilots.  They were warriors, in the truest sense of the word.  They were not just taught to fly, but to fight.  Their hand/eye  coordination was honed to a razor's edge and they were trained to develop their eyesight and sense of balance to almost superhuman heights.  They built very much on the Samurai traditions in the training of the IJN pilots.  Any combat, even in the air, was a 1 on 1 battle for supremacy.  Success, or the lack of it, was considered a direct reflection on the skill of the pilot.  The zero was carefully crafted and designed to suit this type of pilot, and was an incredible leap from the Claude fighters they replaced.  Speed was never consided of more than passing interest until long after they started getting their butts waxed later in the war.  Range, maneuverability, weaponry.  The plane was an extension of the individual to allow him to kill his enemy in the air.  

Even later planes like the Shiden and Hayate were not as fast as they could have been.  They compromised.  Tried to find a balance between what they felt a fighter was all about, and what the Americans did so effectively.  

Just my .02

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 10, 2004, 04:48:20 PM

Hi Star,

Interesting perspective, well written post, but after a thorough analysis, I've reached the conclusion that the facts don't bear it out.

The Japanese always pushed for performance, perhaps with an unusual emphasize on range, and while they valued manoeuvrability high, this didn't influence their designs much. It heavily influenced their pilots' comments, but that's deceptive.

The good manoeuvrability is mostly a byproduct of the low weight which was necessary to get the best performance out of the low-powered engines. Low weight was especially important to get decent high-altitude performance from inferior engine power. It also resulted from the emphasize on range as the high fuel fraction of their designs meant a relatively low combat weight when a good portion of that fuel was already used up.

Regards,

Henning (HoHun)

Title: Why are the Japanese planes so slow?
Post by: StarOfAfrica2 on November 10, 2004, 07:22:34 PM

I suppose it should also be considered that the original design specs for the A6M Zero-sen were submitted in 1937 when the A5M had just entered service.  This is what the IJN asked for in a fighter (which the A6M exceeded in all but one category by the prototype).

1. Maximum speed of 270 kt @ 4,000 m.
2. Climbing speed of 3,000 m in 9 min 30 sec.
3. Endurance of 1.5 to 2 hours at normal rated power.
4. Endurance of 6 to 8 hours at economical speed with drop tanks.
5. Armament of two 20 mm cannon and two 7.7 mm machine guns.
6. Provisions for two 60 kg bombs.
7. Provision for full radio and direction finder.
8. Takeoff run less than 70 m with a 27 knot headwind.
9. Maneuverability at least equal to the A5M.

The only failing of the A6M from this list was that it did not reach required top speed (cannot find top speed of the A6M1 prototype).  I have also read in accounts from two pilots (one would be the book "Samurai!" by Saburo Sakai, the other was an article I read in Warbirds but I cant find the issue right now) that the Zero did not have radios installed during service in WWII, and that is listed as one of the requirements.  


*The Navy ordered two prototypes and plans were submitted by Nakajima and Mitsubishi. Nakajima elected to drop their proposal for a fighter design and Mitsubishi submitted their design led by designer Jiro Horikoshi. The Mitsubishi prototype was the A6M1, retractable gear, all metal, low-wing monoplane, powered with a 780 hp Mitsubishi Zuisei 13 engine. During flight testing, the two-bladed prop variable-pitch propeller was replaced with a three-bladed variable pitch propeller. Apart from maximum speed, all requirements were met or exceeded. The Navy had authorized the production of an initial batch of A6M2s and military trials progressed rapidly. While flight testing the A6M1, a new power plant passed its Navy acceptance tests, and the 925 hp Nakajima NK1C Sakae 12, which was slightly larger than the Zuisei, was installed in the third A6M2 prototype. The initial trials were completed in July 1940 and the navy assigned fifteen A6M2s to combat trials in China. In China the A6M2s, reinforced with a number of production aircraft, destroyed 99 Chinese aircraft with a loss of only two of their own. The aircraft was accepted for production on July 1940 as Navy Type 0 Carrier Fighter Model 11 and in September 1941 were prepared for the impending war with the Allies. Modifications were introduced during production and A6M2 rear spar was reinforced and manually folding wingtips were incorporated to allow clearance on the carriers deck elevators. The modified aircraft was designated Navy Type 0 Carrier Fighter Model 21.  The A6M2 Model 21 was the version utilized at Pearl Harbor and throughout the Pacific, during the early stages of the war. With its maximum speed of 288 kt @ 4,550 m and ability to climb to 6,000 m in 7 minutes 27 seconds, it possessed an ascendancy over any other fighter type in the Pacific. When the war began on December 7, 1941, the Japanese Navy had 328 A6M2s in first line units. *

Rene J. Francillon, Japanese Aircraft of the Pacific War, Mitsubishi A6M Reisen (Zero Fighter). Annapolis, Maryland: Naval Institute Press, 1995. pp 362-365

Title: Why are the Japanese planes so slow?
Post by: F4UDOA on November 10, 2004, 08:17:45 PM

ANGUS!!

Title: Why are the Japanese planes so slow?
Post by: VO101_Isegrim on November 11, 2004, 11:01:51 AM

Quote

Originally posted by Angus
Hai, F4UDOA-san.

Angie, if you really interested to discuss it, lets do it in another thread or something, or by mail by whatever. Whispering death san is right. Cant do it right now, `not at home, no heavy weapons with me. ,)

Title: Why are the Japanese planes so slow?
Post by: Angus on November 11, 2004, 12:56:19 PM

LOL :D

Anyway, some information from a 190 thread that might come in handy.
Crumpp pointed out that the Germans were ahead of anybody else in high quality paint. That influences top speed some little bit.
I wonder how those matters were by the japanese.

Also, something from the back of my head.
I remember that the Zeke had a very thin skin, and even by changes of temperature outside where the aircraft were standing, the expansion of the thin metal would be clearly hearable with popping sounds.
Anyway, when it comes to this, I wonder about rivets, were they high or flushed, and did the thin weight-saving metal give in, - issue being boundary layer you see....:confused: :confused:

Title: Why are the Japanese planes so slow?
Post by: VO101_Isegrim on November 11, 2004, 01:19:04 PM

Quote

Originally posted by Angus
LOL :D

Anyway, some information from a 190 thread that might come in handy.
Crumpp pointed out that the Germans were ahead of anybody else in high quality paint. That influences top speed some little bit.
I wonder how those matters were by the japanese.

Hmm, could be true. I recall George said the LW`s camo paint was of smaller grain size than that of the Allies were using, and certainly George knows his stuff better than anyone else I know. German chemical industry always been - and still is - top notch, even an artist friend of mine said he either uses German or Japanese paints for his art, they are the best. Not sure if this applies to WW2 Japanese paints, though, Japan become a leader in many fields only after WW2.

Title: Why are the Japanese planes so slow?
Post by: HoHun on November 11, 2004, 05:00:23 PM

Hi Flakbait,

>From what Baugher said the lead elevators were corrected when the airframe underwent changes between the pre-production and the full production model.

Thanks, that's interesting.

>The Ki-61 was supposed to get a redesigned engine (Ha-140) for the Ki-61-II model, but it was a nightmare to keep running.

The production count on Baugher's site is puzzling. 374 built, 30 of these destroyed on the ground, 275 built without engines and completed as Ki-100. At first I thought that meant that only 69 were delivered as Ki-61-II, but it seems that the 275 engine-less airframes were built on top of the 374 completed aircraft.

>On the rare occasion when it did run properly, it had 14mph more speed than the KAIc and a much faster climb rate.

Well, I don't trust Baugher's numbers much because he gives two different full throttle heights for the Ha-40. If the Ki-61-II really got 1250 HP @ 5700 m, it was a 400 mph aircraft. (Not that 400 mph is particularly fast.)

>As best I can tell, the Ki-100 was a bit quicker to accelerate than the Ki-61 KAIc and a better climber thanks to an extra 400+ horses.

Sounds reasonable, but of course it depends on the full throttle heights.

Regards,

Henning (HoHun)