USN air combat data from Office of Naval Intelligence

[Tristanjohn]

So where did you get the info about the 12000ft effective fighting altitude, the prop behaviour at 30Kft, the inability to dive up there.....? :rolleyes:

One more point: I didn't mean to say (I doubt I actually did) the "Zero" couldn't perform above 12,000 feet but that it was at this altitude where the pilot noticed sure and certain propeller slip and thus his aircraft's performance at that altitude began to seriously erode. And that struck me as an item of no small significance.

Again. the same thing was happening to other airplanes at the same time and for similar but not necessarily identical reasons.

The problem as I see it with the UV model is that it uses the "Zero" as a kind of universal mark along a linear line of expected performance against which other fighter aircraft in the game should necessarily be and might intelligently be compared, when in fact the "Zero" was just like all other airplanes since the Wright brothers; namely, it was an airplane with individual handling characteristics which must be examined in isolation; and upon such analysis the airplane might then be usefully compared to others in one flight simulation or the other given context of specific circumstance.

In that sort of controlled test environment some insight could be derived; to merely suppose coming in that the "Zero" or any other aircraft design was always superior in all circumstances would be a fool's methodology.

[TheElf]

One more point: I didn't mean to say (I doubt I actually did) the "Zero" couldn't perform above 12,000 feet but that it was at this altitude where the pilot noticed sure and certain propeller slip and thus his aircraft's performance at that altitude began to seriously erode. And that struck me as an item of no small significance.

Again. the same thing was happening to other airplanes at the same time and for similar but not necessarily identical reasons..

An excerpt from "Zero: Combat and Development History of Japan's Legendary Mitsubishi A6M Zero Fighter" ---- this exerpt is from an Army Report of the 2nd Zero captured by the Allies in China, known as the "China Zero".

"the engine performance of the Zero is superior to the present service type engines without superchargers. This superiority is recognized in the fact that maximum manifold pressure can be maintained from sea level to 16,000'. "

From this quote I believe that its possible to conclude that the A6M2's Full throttle altitude, as so perfectly explained by Warspite, is closer to 16,000' than 12,000'. Further, the typical Zero pilot would not see any degradation of power available (Pa) until that altitude.

Of note, an American-made Hamilton Standard propeller was fitted to the "Aleutians Zero" for the testing I posted vs the P-39 earlier, "for both were reported to be identical"

v/r
Elf

Thoughts Warspite?

[Tristanjohn]

An excerpt from "Zero: Combat and Development History of Japan's Legendary Mitsubishi A6M Zero Fighter" ---- this exerpt is from an Army Report of the 2nd Zero captured by the Allies in China, known as the "China Zero".

"the engine performance of the Zero is superior to the present service type engines without superchargers. This superiority is recognized in the fact that maximum manifold pressure can be maintained from sea level to 16,000'. "

From this quote I believe that its possible to conclude that the A6M2's Full throttle altitude, as so perfectly explained by Warspite, is closer to 16,000' than 12,000'. Further, the typical Zero pilot would not see any degradation of power available (Pa) until that altitude.

Of note, an American-made Hamilton Standard propeller was fitted to the "Aleutians Zero" for the testing I posted vs the P-39 earlier, "for both were reported to be identical"

Not necessarily so. Published engine specs are one thing, getting these directly from a manufacturer's service manual or press release is the most reliable course, but even with good specs to work with the powerplant's expected performance in service is but part of the equation.

As I understand it both A6M2 Models 11 and 21 took off propellered by the three-blade variable-pitch Hamilton Standard (this replaced the original two-bladed job on the A6M1 which had vibration issues), and I believe this propeller was manufactured under license by Sumitomo. (I'm not completely sure what you mean by the "Aleutian" plane. I know, for instance, that the Swordfish was modeled differently (enclosed cockpit) for Canadian (colder climate) use, so maybe that's it.)

The new powerplant for the third and final prototype was tested in 1940 for A6M2 or "Zero" Model 11: Nakajima NK1C Sakae 12 radial, with 690 kW or 925 hp giving this plane a top end of 332 mph. This is said to have been "turbocharged" but its performance for that kind of engine technology was not very impressive to judge by the performance specs at altitude I've seen, certainly well below what we've come to expect from the turbocharger technology of Rolls Royce and Allison.

The problem is to find a consensus of reliable opinion (i.e., opinion based, as far as these things go in the real world, on fact) regarding specific behavior characteristics of Japanese aircraft with regard to engine performance at various altitudes.

That requires time and loads of patience. You want to know the sort of time wasting I'm regulalrly subjected to? Check out this innocent-looking (at first glance) link: http://www.militarytv.com/

Moving right along . . .

. . . the next major "Zero" variant was the A6M3 Model 32, first flown in the late spring of 1941. This aircraft had for its powerplant the Nakajima NK1F Sakae 21 which sported supposedly a two-speed turbocharging technology and generated 845 kW or 1,130 hp. It's supposed to have been fitted to a somewhat wider propeller, but of what pitch and material build I don't know, and what the actual performance specs for this engine might have been at any given altitude I don't know for sure, either. (I believe I've already posted what I consider to be representative figures, but I wouldn't bet my life on any of them.)

Weight "creep" was definitely in the works as the Model 32 loaded out around 100 pounds heavier, maybe more than that, though on the other hand wing loading was eventually reduced somewhat when the clipped wingtips of the early models of the A6M3 (actually the earliest planes came with the same folding wingtips as the carrier-borne Model 21's) were lost . . . the Japanese production cycle followed almost comically close on the heels of that old vaudeville schtick, "Hey that's good! No that's bad!" . . . and of course the beefier Sakae 21 drank more gas than the A6M2's and thus a little item called endurance took a hit . . . and like that.

All these engines, as far as I know, were nominally rated to be fueled with 92 octane avgas, though in practice, especially as the war wore on, I have to wonder just what amounts of this quality of fuel were actually available in theatre (this detail alone might account for some pilot reports of "slippage" at higher altitudes--how would you feel up there when you found out they'd been pumping 87 regular instead--though this is speculation on my part).

Anyway, aside from the clipped wings on the "second" of the A6M3's it was somewhat difficult to distinguish it from the A6M2, the most visible difference being that the A6M2 had the supercharger air intake in the lower lip of the cowling while the A6M3's intake was moved to the top. The initial A6M3 variant was designated the "Model 32" and 343 were built. So say some sites.

And to be frank, at this juncture I'm not even clear about what your original question was.

[TIMJOT]

. (I'm not completely sure what you mean by the "Aleutian" plane. I know, for instance, that the Swordfish was modeled differently (enclosed cockpit) for Canadian (colder climate) use, so maybe that's it.)

Tristanjohn

He is refering to the Aleutian zero recovered nearly intact in 1942 (I forget Attu or Kiska) and consequently refurbished and flown by US test pilots against then current US fighters ( F4F, P-40, P-39, P-38 ). He is pointing out that they replaced the damaged prop with one of indentical specs.

The performance specs he is refering to are not factory specs, but the specs as determined by these Test pilots while conducting one on one test vs the above mention US designs. The data obtained in the test was used as a benchmark in the developement of the F6F Hellcat. They ougth to be considered fairly definitive in regards the the actual performance characteristics of the A6M Zeke.

[TheElf]

And to be frank, at this juncture I'm not even clear about what your original question was.

I didn't ask any questions. Merely providing info.

[TheElf]

Of note, an American-made Hamilton Standard propeller was fitted to the "Aleutians Zero" for the testing I posted vs the P-39 earlier, "for both were reported to be identical"



Thoughts Warspite?

The point of this post was to point out that the Prop on the A6M2 was Identical to a well-known American made Prop.

You have held pretty consistently and regularly (with no evidence mind you )that one of the Zero's deficiencies was propeller "slippage" (or some such thing).

I thought it might show that whatever difficulties the Zero may have had with it, and whatever advantage it yielded due to this inefficient prop design, (someone help me locate that post ) it is likely that it was a "disadvantage" that BOTH American AND Japanese aircraft experienced.

Thus for non-supercharged engine aircraft they would effectively cancel each other out. So...can we dispense with the unfounded claims that the Japaneses made inefficient propellers from here on out?

v/r
Elf

[mdiehl]

The performance specs he is refering to are not factory specs, but the specs as determined by these Test pilots while conducting one on one test vs the above mention US designs. The data obtained in the test was used as a benchmark in the developement of the F6F Hellcat. They ougth to be considered fairly definitive in regards the the actual performance characteristics of the A6M Zeke.

Note: emphasis mine.

The boldfaced text is wholly incorrect. The F6F design specs were issued in 1941 and the general design was already known by 1942. The first production prototype XF6F-1 flew in June 1942 with a Wright R2600 Cyclone. Three other XF6Fs were in the final stage of presentation but the Navy decided to get the airplane to the front as fast as possible. An executive decision was made, on 26 June 1942, prior to the testing of the other XF6s or the "Akutan Zero" (see below), to put the Pratt and Whitney R2800 Double Wasp radial in the plane. The resulting aircraft was for a short term called the XF6F-3. (The XF6F-2 and XF6F-4, with different engines, were never completed).

The first units with the F6F-3 were on the USS Essex in December 1942.

The "Aleutians Zero" aka the "Akutan Zero" (after the Island on which it was found) was shot down on 4 June 1942 after the Battle of Midway, as it had crash landed as part of the diversionary effort with the Japanese CVs tasked to make a feint at the Aleutians. The damaged plane was recovered in July (it was first spotted by a recon plane 5 weeks after it crashed), crated, and shipped to California for repair and evaluation. Trials of the repaired Zero began well after the F6F-3 had been accepted as the first full-up production Hellcat.

The only aircraft that was modified as a reaction to the "Aleutians Zero" was the F4F. The Ironworks continued to produce standard F4F-4s until they retooled for the F6F. GM and Ford produced the modified F4F that we know as the "FM-2 Wildcat." It had modified propellor, lighter armament, a more powerful engine, and a larger rudder. The greater thrust provided by the engine, a better propellor, and the lighter weight (the seat armor was optimized, lightening it yet according the same protection, and two .50cals were removed, further lightening the plane), made the FM2 somewhat more maneuverable at its lower speeds, but not enough to offset any advantage held by the Zero in low speed engagements. The chief benefits that accrued from lightening the FM2 were to extend its range, increase its maximum airspeed and climb rates, and give a little more ammo to the 4 x.50 cal MGs.

[TIMJOT]

. Trials of the repaired Zero began well after the F6F-3 had been accepted as the first full-up production Hellcat.
.

Mdiehl,

I did not mean to imply that the Hellcat was "designed" based the performance specs of the Aluetian Zero. Just that the performance specs acertained by testing the captured Zero were used as a "benchmark" in the subsequent flight testing of the already designed F6F. Basically it confirmed the validity of the design.

[HMSWarspite]

An excerpt from "Zero: Combat and Development History of Japan's Legendary Mitsubishi A6M Zero Fighter" ---- this exerpt is from an Army Report of the 2nd Zero captured by the Allies in China, known as the "China Zero".

"the engine performance of the Zero is superior to the present service type engines without superchargers. This superiority is recognized in the fact that maximum manifold pressure can be maintained from sea level to 16,000'. "

From this quote I believe that its possible to conclude that the A6M2's Full throttle altitude, as so perfectly explained by Warspite, is closer to 16,000' than 12,000'. Further, the typical Zero pilot would not see any degradation of power available (Pa) until that altitude.

Of note, an American-made Hamilton Standard propeller was fitted to the "Aleutians Zero" for the testing I posted vs the P-39 earlier, "for both were reported to be identical"

v/r
Elf

Thoughts Warspite?

Well - if a US HS prop was fitted, and there is anything in TJs views on the Jn prop, that would seriously question the test results. However, I still do not understand why the Jn prop should be below standard - assuming is isn't fixed pitch, what exactly was wrong with it? You don't happen to know why they swapped the prop (although v likely bent in the landing!). The testers would have known (or should have spotted) if the prop was low tech, just by inspection, and should have commented. Also, I hope they would have compared their achieved performance with combat reports, and spotted any marked difference.

[HMSWarspite]

The point of this post was to point out that the Prop on the A6M2 was Identical to a well-known American made Prop.

You have held pretty consistently and regularly (with no evidence mind you )that one of the Zero's deficiencies was propeller "slippage" (or some such thing).

I thought it might show that whatever difficulties the Zero may have had with it, and whatever advantage it yielded due to this inefficient prop design, (someone help me locate that post ) it is likely that it was a "disadvantage" that BOTH American AND Japanese aircraft experienced.

Thus for non-supercharged engine aircraft they would effectively cancel each other out. So...can we dispense with the unfounded claims that the Japaneses made inefficient propellers from here on out?

v/r
Elf

Seconded (I didn't read this post when I did my one above. There doesn't seem any evidence for the dodgy prop theory at present (nor an understanding of how it would be dodgy). Over to you, Allied fanboys

[mdiehl]

I did not mean to imply that the Hellcat was "designed" based the performance specs of the Aluetian Zero. Just that the performance specs acertained by testing the captured Zero were used as a "benchmark" in the subsequent flight testing of the already designed F6F. Basically it confirmed the validity of the design.

Timjot -

Thanks for the clarification. My apologies if I sounded pedantic.

[mdiehl]

The Akutan Zero was somewhat scragged by the landing. It came down in a bog and flipped over. Apparently the pilot mistook the landing area for firm ground and lowered his landing gear. The pilot, who had no obvious combat injuries, either died of a broken neck or from being suspended upside down, unconscious, with his head under water. There is obvious damage to the propeller (the blade pointing at 2 O-clock in the picture looks bent to me). In a subsequent photo you see an American recovery crew working on it and the blade appears to have been rotated to about 11 O'clock in the photo. It again looks bent (if that's the same blade). There is likely some damage to the upper control surfaces given that it is upside down. The landing gear is not in view, either because they were destroyed as the plane flipped or because the hydraulic system ruptured and the gear flipped back into the wheel wells.

Here is a link to a web page that, quite far down (you will have to search through lots of pictures and drawings of various guns and aircraft), has a photograph of the Akutan Zero in situ (lying on its back in bog) before it was hauled away for repair and evaluation.

http://www.geocities.com/CapeCanaveral/ ... vypby.html

The same web page stipulates that the aircraft was rebuilt starting on 12 August 1942, and that flight evaluations revealed that the A6M2 flown by Koga had some of the same problems as the early war Spitfires... a tendency for the engine to cut out for want of fuel in a push-over owing to negative gravity in the fuel feed. Never heard that claim before.

Nothing that I have ever read suggests that the Zero's propellor had any intrinsic flaw that adversely affected performance.

[mogami]

Hi, I have been unable to find any data that supports the Zero suffered any adverse effects from Altitude below 15k I have found mentions of handling decline above 15k. I think it might be a good thing to expand the altitude penalty to all aircraft when it can be detirmed where the effects begin. Perhaps every 1k is too much but then it would depend on the particular aircraft. Aircraft designed for higher altitudes would of course be less likely to suffer (If the design was successfull)

I don't know how much expansion can be placed into aircraft stats but if they could be entered by altitude that would be a good thing.


Out of curiosity, Where would you set altitudes? Since interceptors move to altitudes of Bombers would you fly bombers where enemy was adversely effected or where your fighter escort had top performance?

[mdiehl]

For what it's worth (the guy "sounds like" he knows what he's talking about:

There were 2 propellers used on the Zeros at this time. The A6M2 is documented to have used a variable pitch (25° to 45°) 140-kilogram Hamilton-Sumitomo 3-blade CS-40B propeller with a 2.9-meter diameter. The A6M3's 145.3-kilogram Hamilton-Sumitomo 3-blade propeller pitch varied from 29° to 49° and had a diameter of 3.05 meters.

Current research defines A6M2 Zeros as Nakajima- or Mitsubishi- built, based on (among other things) the spinner. Many exceptions appear upon close inspection. While some of these exceptions may pan out to be field adaptations or modifications, evidence shows these different spinners are actually dependent more on the date of manufacture and less on the different contractors (Mitsubishi and Nakajima). A6M3 Model 32 production began in June of 1942, and this seems to be an acceptable "long spinner" adaptation timeframe. A6M2-N floatplane fighters probably retained the blunt spinner until later, possibly around April of 1943.About 120 Nakajima A6M2s (plus about 20 A6M2-Ns) were built prior to this date; 181 out of the 254 total A6M2-Ns were produced by April of 1943.

from: http://members.aol.com/reishikisenguy/z ... ails_2.htm

I can find no mention of any adverse effects on the A6M2 owing to propeller design. All A6M2s had variable-pitch props. From the description "Hamilton-Sumitomo" it's pretty apparent to me the basic design was taken from a Hamilton Standard prop. I don't think there is any reason to suppose that the Akutan Zero's evaluation flights were biased by any supposed improved performance resulting from the use of a Hamilton Standard prop.

[Tristanjohn]

The point of this post was to point out that the Prop on the A6M2 was Identical to a well-known American made Prop.

You have held pretty consistently and regularly (with no evidence mind you )that one of the Zero's deficiencies was propeller "slippage" (or some such thing).

I thought it might show that whatever difficulties the Zero may have had with it, and whatever advantage it yielded due to this inefficient prop design, (someone help me locate that post ) it is likely that it was a "disadvantage" that BOTH American AND Japanese aircraft experienced.

What you write in part would only "true" in a narrow and select context and in any event misleads the discussion at hand. So basically the thrust of your writing is untrue in nature, depending always on what American airplane designs we're speaking to--but then none of this is about comparative design attributes and/or deficiencies between WWII Japanese and American aeronautical engineering technology but rather suspected flight deficiencies of just one aircraft, the "Zero."

Thus for non-supercharged engine aircraft they would effectively cancel each other out. -------------------So...can we dispense with the unfounded claims that the Japaneses made inefficient propellers from here on out?Elf

Wrong re the first part, if I understand you (and that is something I'm learning fast to be not guaranteed, Elf), while the short answer to the section I've emphasized in boldface is: no.

The long answer to that section is . . . well, long unless I miss my bet, but I haven't composed my reply to that thought yet so we'll see. Meanwhile, I've stuff to do today more pressing than this back-and-forth which-language-do-you-speak? why-can't-you-look-some-of-these-things-up-for-yourself? nonsense.

Maybe I'll find time later this evening but I don't know.

In my absence you'd do yourself a great service to get off this kick of trying to prove TJ wrong and approach these issues with a more open mind and willingness to pursue "truth" wherever that ideal might care to lead . . . for that's the thing to do.

To put it differently, if you could point out errors in my research or thinking then I'd take it as both useful and complimentary for you to so demonstrate; if, on the other hand, you were to expend your energy negatively (i.e., with the sole bent to simply disprove anything I might write merely because I wrote it and you wish to prove me wrong) then I put it to you you're entirely likely to miss the larger "forest of truth" for the "many smaller factual trees" along the way.

But as always, do it your way.

[Tristanjohn]

For what it's worth (the guy "sounds like" he knows what he's talking about :



from: http://members.aol.com/reishikisenguy/zero_details_2.htm

I can find no mention of any adverse effects on the A6M2 owing to propeller design. All A6M2s had variable-pitch props. From the description "Hamilton-Sumitomo" it's pretty apparent to me the basic design was taken from a Hamilton Standard prop. I don't think there is any reason to suppose that the Akutan Zero's evaluation flights were biased by any supposed improved performance resulting from the use of a Hamilton Standard prop.

Thanks for the link. It probably explains that "wider" blade I made reference to earlier. I'll need to read the entire Graham article for full meaning (later) but a quick scan doesn't seem to indicate he addresses the central issue--this I'll get into, time permitting, this evening, or by this weekend failing that.

[TheElf]

I can find no mention of any adverse effects on the A6M2 owing to propeller design. All A6M2s had variable-pitch props. From the description "Hamilton-Sumitomo" it's pretty apparent to me the basic design was taken from a Hamilton Standard prop. I don't think there is any reason to suppose that the Akutan Zero's evaluation flights were biased by any supposed improved performance resulting from the use of a Hamilton Standard prop.[/QUOTE]


They were built under license in Japan from Hamilton

Elf

[mdiehl]

They were built under license in Japan from Hamilton

Yep, that's about how it seems to me. Of course there's a certain irony in the phrase "license built" after Dec 1941. Hamilton: "Hey Sumitomo, now that we're at war with each other your license is void." Sumitomo: "OK. Just hand deliver that note to our office in Tokyo and we will comply with our legal obligations."

[TheElf]

Yep, that's about how it seems to me. Of course there's a certain irony in the phrase "license built" after Dec 1941. Hamilton: "Hey Sumitomo, now that we're at war with each other your license is void." Sumitomo: "OK. Just hand deliver that note to our office in Tokyo and we will comply with our legal obligations."

I thought that was pretty ironic too.

[TheElf]

What you write in part would only "true" in a narrow and select context and in any event misleads the discussion at hand. So basically the thrust of your writing is untrue in nature, depending always on what American airplane designs we're speaking to--but then none of this is about comparative design attributes and/or deficiencies between WWII Japanese and American aeronautical engineering technology but rather suspected flight deficiencies of just one aircraft, the "Zero."

This entire thread as far back as I can remember was running in parallel to the P-39D. Where have you been???? The "thrust" of my writing has only been to provide information on the P-39D and, as you shifted the discussion to the relative shortcomings of the Zero, to provide info on that airframe. Here and there I have drawn SOME conclusions, but mostly I try to bring accuracy to the discussion through cited sources. Recently Warspite added much to this P-39/Zero discussion with a very well written explanation of Super-chargers. In and among these posts you have repeatedly claimed the Zero's PROPELLER was a contributing cause for its loss of performance. AGAIN...the reason for the previous post was to point out that this "inefficiently" designed prop was identical to a common American made one. Therefore, your Unfounded unresearched stance has no leg to stand on re: the zeros prop v any Aircraft with the Hamilton Std prop. Further I limited the comparison above to A/C lacking superchargers(P-39/Zero). OF COURSE this wouldn't apply to US designs that don't use the same prop. My mistake I assumed everyone would understand that... more to come.