The Zero's Maneuverability (1 Viewer)

[Ivan1GFP]

I didn't mention external tanks, Ivan. The 134 gallons above is all internal. It is also A6M3 Model 32.

I can certainly find out the fuel capacity for the A6M5 Model 52 since we fly one, but I'd not bother the people about it until the airshow was over ... which it was 2 weeks ago. So, this weekend is a good time to ask and we HAVE the information if only the correct people are around on Saturday.

The link I sent you was listing internal fuel for all models of A6M along with the capacity of the typically used drop tank.
There is a little more detail on internal arrangement of tanks further down in that thread.
I posted this data about 5 years ago. It is from a translated copy of the manual captured on Kwajalein.
You don't need to bother anyone on Saturday.

 

[Holtzauge]

Regarding the use of settings above their "Military" rating, we have the claim by Mr. Saburo Sakai of the A6M2 being able to achieve 345 MPH on "Overboost" setting.
We also have corroborating evidence in the third of the reports posted by R Leonard (SWP Report).
Read the comments section.
The Sakae was apparently a well built and tough engine as later TAIC reports about "Flash Performance" from Oscar and Mr. Sakai's encounter with a squadron of Hellcats would seem to indicate.

This particular report and most others that show some detail on Koga's rebuilt A6M2 seem to indicate that all was not right with the carburetor.
There are comments showing a bit of surprise when thing appear to be running correctly. There was also a mention of the automatic mixture control not actually working. I believe this was by Corky Meyer. The pilot found that after a bit of climbing, the engine was starting to misbehave until it was leaned out.
This particular engine had spent a month with part of it underwater. When rebuilt, it had to have a couple cylinders resurfaced. I do not know whether the carburetor was also underwater.
In many of the test reports on Koga's A6M2, the critical altitude seems a bit too low and for some reason they are running the engine as if they believe 2550 RPM is the proper limit.
I don't recall ever seeing a test run at 2600 RPM, so if you know where I can find that, I would appreciate it. There was speculation that 2600 RPM was the limit but I haven't actually found a test report showing this was done in a test flight.

Regarding 60 inches of boost on the P-40E at altitude. I believe you are being VERY optimistic. This level of performance was more characteristic of later Allison engines that did not run out of breath quite so low.

Regarding fuel loads: Spitfire and Me 109 both had just over 100 US Gallons of internal fuel. Both were also known for having very short ranges. What I found interesting was that Hurricane wasn't that much better at only 116 Gallons. You wonder why US was complaining about the Airacobra with 120 Gallons.
Of the reports, the 141 Gallon internal fuel load for A6M2 is closest to correct. It should really be about 141.3 US Gallons or 480 Liters nominal.

I've read other things that Sakai has said in his memoirs about fuel consumption and ranges etc, and he does seem to have a good recollection of numbers.

But tuning simulation models based on pilot quotes alone is risky business just for the reasons tyrodtom mentioned in his post above. In addition, IAS read off on a dial in a cockpit need to be converted to CAS and the POC can be quite large in some cases.

This test of Koga's Zero you mention, which one was it? There are a number of different Allied trial reports on the Zero and I'm not sure which test you are referring to?

I include a screenshot below from the Wright Field test I mentioned earlier in which they ran the engine at 2600 rpm. You can find the complete report with speeds, climb rates and technical data from that test here:

http://www.wwiiaircraftperformance.org/japan/a6m2-oct2342.pdf

 

[Ivan1GFP]

I've read other things that Sakai has said in his memoirs about fuel consumption and ranges etc, and he does seem to have a good recollection of numbers.

But tuning simulation models based on pilot quotes alone is risky business just for the reasons tyrodtom mentioned in his post above. In addition, IAS read off on a dial in a cockpit need to be converted to CAS and the POC can be quite large in some cases.

This test of Koga's Zero you mention, which one was it? There are a number of different Allied trial reports on the Zero and I'm not sure which test you are referring to?

I include a screenshot below from the Wright Field test I mentioned earlier in which they ran the engine at 2600 rpm. You can find the complete report with speeds, climb rates and technical data from that test here:

http://www.wwiiaircraftperformance.org/japan/a6m2-oct2342.pdf

View attachment 799327

I looked through the report you provided a link for.
I see the mention that the propeller settings would allow for a maximum of 2600 RPM, but there is nothing in the actual speed runs that states that was the RPM being used.

As for Sakai and his statement of 345 MPH on overboost, what would that look like to an opposing pilot?
How about this: (from comments in SWP report)

Comments: Mention is made of a form of automatic boost control which limits
the manifold pressure to 35". Further mention should be made here of the fact
that there is a manual over ride which permits the manifold pressure to exceed
35" and obtain maximum boost from the engine. It is thought that this gives
the dense black smoke reported often in combat in connection with unusual
bursts of speed. In some instances this smoke has been attributed to injection
of some chemicals but it is felt that this is the result of of the manual over ride.

The section following this describes messing with the propeller pitch range to try to get the engine to wind up the way they were expecting.
The difficulty here is suggestive either of a propeller that is overly large or non-optimal gearing for the engine or an engine that isn't achieving the torque that it should be.

 

[Ivan1GFP]

Regarding the use of settings above their "Military" rating, we have the claim by Mr. Saburo Sakai of the A6M2 being able to achieve 345 MPH on "Overboost" setting.
We also have corroborating evidence in the third of the reports posted by R Leonard (SWP Report).
Read the comments section.
The Sakae was apparently a well built and tough engine as later TAIC reports about "Flash Performance" from Oscar and Mr. Sakai's encounter with a squadron of Hellcats would seem to indicate.

This particular report and most others that show some detail on Koga's rebuilt A6M2 seem to indicate that all was not right with the carburetor.
There are comments showing a bit of surprise when thing appear to be running correctly. There was also a mention of the automatic mixture control not actually working. I believe this was by Corky Meyer. The pilot found that after a bit of climbing, the engine was starting to misbehave until it was leaned out.
This particular engine had spent a month with part of it underwater. When rebuilt, it had to have a couple cylinders resurfaced. I do not know whether the carburetor was also underwater.
In many of the test reports on Koga's A6M2, the critical altitude seems a bit too low and for some reason they are running the engine as if they believe 2550 RPM is the proper limit.
I don't recall ever seeing a test run at 2600 RPM, so if you know where I can find that, I would appreciate it. There was speculation that 2600 RPM was the limit but I haven't actually found a test report showing this was done in a test flight.

Regarding 60 inches of boost on the P-40E at altitude. I believe you are being VERY optimistic. This level of performance was more characteristic of later Allison engines that did not run out of breath quite so low.

Regarding fuel loads: Spitfire and Me 109 both had just over 100 US Gallons of internal fuel. Both were also known for having very short ranges. What I found interesting was that Hurricane wasn't that much better at only 116 Gallons. You wonder why US was complaining about the Airacobra with 120 Gallons.
Of the reports, the 141 Gallon internal fuel load for A6M2 is closest to correct. It should really be about 141.3 US Gallons or 480 Liters nominal.

That should have been 535 Liters.
Got numbers confused with slightly different discussion with GregP about Model 32.

 

[Holtzauge]

I looked through the report you provided a link for.
I see the mention that the propeller settings would allow for a maximum of 2600 RPM, but there is nothing in the actual speed runs that states that was the RPM being used.

Now that there, is some very creative reading of the wording in the report which is this:

"NOTE: For these tests the propeller setting used permitted a maximum RPM of approximately 2600 and the manifold pressure is automatically regulated to 35" below critical altitude."

In addition, even the SWP report you yourself refers to, both under "Comments" and "ENGINE" mentions that the estimated rated rpm was 2600.

As for Sakai and his statement of 345 MPH on overboost, what would that look like to an opposing pilot?
How about this: (from comments in SWP report)

Comments: Mention is made of a form of automatic boost control which limits
the manifold pressure to 35". Further mention should be made here of the fact
that there is a manual over ride which permits the manifold pressure to exceed
35" and obtain maximum boost from the engine. It is thought that this gives
the dense black smoke reported often in combat in connection with unusual
bursts of speed. In some instances this smoke has been attributed to injection
of some chemicals but it is felt that this is the result of of the manual over ride.

The section following this describes messing with the propeller pitch range to try to get the engine to wind up the way they were expecting.
The difficulty here is suggestive either of a propeller that is overly large or non-optimal gearing for the engine or an engine that isn't achieving the torque that it should be.

Well in the SWP report they also mentioned that the BUAER tests were not completed at the time the report was compiled, and this of course opens up the possibility that it was mentioned somewhere else in a later report. And for sure, if there was such a manual override and it could increase boost, say from +150 mm to a WEP of +250 mm (which as I understand it was the take-off boost?), then an increase in speed from the 335 mph at 35" (+150 mm) boost would of course be quite feasible.

But do we have any such data? Was it for example possible to go to +250 mm at the FTH? And if so, for how long could you run it like that? 1, 5, or 10 mins? Until we know, the best I've seen so far is the 335 mph at 16,000 ft with 35" and 2600 rpm. However, if some new solid data emerges suggesting a WEP setting with +250 mm or something else, then that would of course warrant an update of the modeling for me.

 

[MIflyer]

Here is another report on a captured Zero I just found. Note they removed 1500 pounds as part of the refurb and the controls STILL got very stiff above 200 kt.

 

[wrathofatlantis]

I've been shot at in a chopper, actual combat, and it's pretty stressful.
I've also circle track raced myself from 1996-2016, helped and spotted ( radio) for other racers at NASCAR, ARA, and other tracks from 1990-to present.

I won't say racing is as stressful as combat, maybe a 6 on a scale of 10.

But I've noticed I can't or any other racer I've been around can keep track of what lap they're on without outside help, like seeing the lap number on the score board, you're exsisting in the second, using every sense you have just to keep the vehicle under control till the next second, you can plan ahead, to some extent, but your mind is in survival mode, not record mode.
When it's over you remember some, but jumbled sometimes, out of order.

One of my early sponsors was a guy that videoed every race. He gave me videos of every race I was in.
Later I would watch those videos, and realize sometimes I didn't remember things in the way they actually happened.
And that's not unique to me alone.
For years afterward we also had GOPRO recorders in the car also.

The human mind is just not equipped to record accurately under stress.
They're not cameras, they're not recorders, they're not computors, they're humans beings.
Maybe rare individuals can, but they're very rare.
So rare I don't think I've ever met any.

Some of you seem to believe perfect recall, of events that happen 50-60, maybe even 70 years before.

I notice the pilot said he circled PROBABLY 75-100 circles. A big variation, and then there is that "probably".
I know most aircraft of that era had clocks.
How many pilots do you think wrote down the time when they entered a dogfight, and again wrote down when it ended?
I think we all know it's just a guess.

I read hundreds of books too, on aerial combat, watched many videos, but I've always realized they're just memories of a human mind.
My dad, and two of my uncles were WW2 Marine veterans, all fought in the Pacific.
We had some interesting family get togethers, this was in the 50's early 60's, I'd try to soak up all they had to say.
I was in my early teens, they were in their late 30's or 40's, about 15-20 years since the war.
Even then I could see that some of their recall of events getting meshed, re-arranged, that they didn't have perfect recall.
They were my heroes , but they were still human.

His inaccuracy under stress is taken into account by him, which is why he says 75-100 circles.

All of you, on the other hand, have trouble figuring out how this is possible, because you had no conception of the "no rolling out" rule, without which you can have no understanding of why that situation was the way it was.

You don't have the most basic understanding of the facts, and are dismissing the account of a P-51 ace because it doesn't fit your understanding of how WWII turn fighting worked.

You also have likely not read 1/10th of the combat accounts I have read, which allowed me to collect the 3 general quotes concerning how rolling out was "stupid" "fired short bursts to try to get him to roll out, but he was too smart to do it", and "the majority of our kills were made good when the kraut reversed his turn: NEVER REVERSE YOUR TURN."

Pilots of the time will rarely disrepect an opponent by calling his actions stupid. They will do it only if it is an eggregious error. The fact you are unaware of this simply demonstrate your lack of first hand knowledge.

So there is no need to pontificate on vague generalities about the fallibility of human memory. That is not the source of the problem here.

 

[tyrodtom]

His inaccuracy under stress is taken into account by him, which is why he says 75-100 circles.

All of you, on the other hand, have trouble figuring out how this is possible, because you had no conception of the "no rolling out" rule, without which you can have no understanding of why that situation was the way it was.

You don't have the most basic understanding of the facts, and are dismissing the account of a P-51 ace because it doesn't fit your understanding of how WWII turn fighting worked.

You also have likely not read 1/10th of the combat accounts I have read, which allowed me to collect the 3 general quotes concerning how rolling out was "stupid" "fired short bursts to try to get him to roll out, but he was too smart to do it", and "the majority of our kills were made good when the kraut reversed his turn: NEVER REVERSE YOUR TURN."

Pilots of the time will rarely disrepect an opponent by calling his actions stupid. They will do it only if it is an eggregious error. The fact you are unaware of this simply demonstrate your lack of first hand knowledge.

So there is no need to pontificate on vague generalities about the fallibility of human memory. That is not the source of the problem here.

If he didn't or couldn't keep count of how many turns he made, it's just a guess.

What I find amazing is that the guy behind him would do 75-100 turns behind him before he finally decided it wasn't going to work.
It wouldn't be fatal for the German to reverse his turn, and that's probably how he broke off the combat.

Staying on one opponent so long, in the same airspace, while the Mustang pilot is on the radio trying get all his buddies to come help him, just doesn't seem smart, or likely.

You seem to have your own misunderstanding of basic facts.

 

[Greg Boeser]

In a combat environment with dozens of planes swirling about, at 200 - 300 mph, it's not likely that yelling into your mic is going to produce the results you want.

 

[Thumpalumpacus]

The fact you are unaware of this simply demonstrate your lack of first hand knowledge.

What first-hand knowledge of WWII dogfighting do you have? What plane(s) did you fly? Where? Did you get any kills? Did you fly circles?

Tell us you first-hand experience of WWII aviation combat, please.

 

[Ivan1GFP]

Now that there, is some very creative reading of the wording in the report which is this:

"NOTE: For these tests the propeller setting used permitted a maximum RPM of approximately 2600 and the manifold pressure is automatically regulated to 35" below critical altitude."

In addition, even the SWP report you yourself refers to, both under "Comments" and "ENGINE" mentions that the estimated rated rpm was 2600.



Well in the SWP report they also mentioned that the BUAER tests were not completed at the time the report was compiled, and this of course opens up the possibility that it was mentioned somewhere else in a later report. And for sure, if there was such a manual override and it could increase boost, say from +150 mm to a WEP of +250 mm (which as I understand it was the take-off boost?), then an increase in speed from the 335 mph at 35" (+150 mm) boost would of course be quite feasible.

But do we have any such data? Was it for example possible to go to +250 mm at the FTH? And if so, for how long could you run it like that? 1, 5, or 10 mins? Until we know, the best I've seen so far is the 335 mph at 16,000 ft with 35" and 2600 rpm. However, if some new solid data emerges suggesting a WEP setting with +250 mm or something else, then that would of course warrant an update of the modeling for me.

Technical Aviation Intelligence Brief No. 3 in paragraph 4 states 2550 to 2575 RPM was used for testing.
I forget where, but there is a note that the governor allowed settings up to 2600 RPM which is where the technicians got the idea that the maximum engine RPM was 2600.
Every place where a specific RPM is specified doesn't list anything above 2550 RPM however.

One thing worthy of note is that the often listed 35" Hg Manifold Pressure actually corresponds to +129 mm boost. When some of these descriptions were talking about using "take-off power", they raised the RPM a bit but never really got the Manifold Pressure correct.

Consider the evidence. Allied pilots report an unusual burst of speed which means it is significant enough to be noticeable.
A 50-100 increase in engine RPM in an opposing aircraft probably will not be noticeable. Black smoke corresponding to the increased performance was suggesting either some kind of chemical injection or a manifold pressure increase and it WAS noticeable.

One has to also consider what each speed really means relative to contemporary aircraft. 326 MPH meant that the early Wildcats were substantially faster. Hurricanes would also be faster. 335 MPH would be pretty much even with the early Wildcats.
As Richard Dunn pointed out, when these reports were distributed, pilots who had encountered the A6M2 stated that the reports were simply wrong and that the Type Zero was actually faster.

As for what you want your simulator model to do, that is really your own business. I built a flight simulator A6M2 almost a decade ago and as I read through more reports, I believe now that I should have made it considerably faster.

 

[Ivan1GFP]

His inaccuracy under stress is taken into account by him, which is why he says 75-100 circles.

All of you, on the other hand, have trouble figuring out how this is possible, because you had no conception of the "no rolling out" rule, without which you can have no understanding of why that situation was the way it was.

If you are doing more than about three circles (and I believe I am being generous), you basically are inviting the wingman or a passerby to eat you for lunch because your flight path is so predictable. You are also bleeding energy and losing other maneuver options. There are ways to get out of the circle other than rolling out. Think of getting out of the geometric plane of the circle such as with a high or low yo-yo or some other vertical maneuver depending on your relative positions on the circumference of the circle.

 

[SaparotRob]

..So there is no need to pontificate on vague generalities about the fallibility of human memory...

No need to pontificate? No need to pontificate!?
Pontification, Sir, is the primary force that awakens me from slumber! Pontification is the glue that bolts together the tapestry of communication. How else might one bring enlightenment to those foundering on reefs ignorance? How may misguided intellects cast upon on the shoals of ignorance find guidance without our bonfires of brilliance? When one has achieved enlightened insight, without the distraction of peer review, it must be told. Nay, it must be broadcast. Broadcast I say! Through all means possible. If anonymous web sites, forums, local newspapers or crudely posted handbills are required, then they must be used. From early human beings gathered around fires, the village wisemen, shamans, alte kakes and yentas have had to bring understanding to the hidden truths hidden from those using simple logic or truth. I myself have had to expound frequently and at length despite just enjoying hearing myself talk. It would be negligent of our moral compasses not to steer our blithely ignorant fellows to the chapel of smart. Standing on the soapbox of awareness, it would be shameful, nay, a sin to not clear the mists of obviousness of incoherent thought. Anyone still reading this drivel? Pontification is an unstoppable force of the irresistible nature of ignoring whatever anyone else may care and just keep blathering away until they get your point. Or just the enjoyment of hearing oneself talk. Pontification is not only a sacred freedom enshrined in the constitutions of our foremost nations as well as most public lavatory walls. It therefore cuts across all social and economic strata as the gift of education, asked for or not! I do not know your beliefs, Sir, but I believe in these sacred freedoms. I believe in the Constitution of the United States, the Magna Carta and the Rights Of Man. Give me pontification, or give me death!

 

[Greg Boeser]

No need to pontificate? No need to pontificate!?
Pontification, Sir, is the primary force that awakens me from slumber! Pontification is the glue that bolts together the tapestry of communication. How else might one bring enlightenment to those foundering on reefs ignorance? How may misguided intellects cast upon on the shoals of ignorance find guidance without our bonfires of brilliance? When one has achieved enlightened insight, without the distraction of peer review, it must be told. Nay, it must be broadcast. Broadcast I say! Through all means possible. If anonymous web sites, forums, local newspapers or crudely posted handbills are required, then they must be used. From early human beings gathered around fires, the village wisemen, shamans, alte kakes and yentas have had to bring understanding to the hidden truths hidden from those using simple logic or truth. I myself have had to expound frequently and at length despite just enjoying hearing myself talk. It would be negligent of our moral compasses not steer our blithely ignorant fellows to chapel of smart. Standing on the soapbox of awareness, it would be shameful, nay, a sin to not clear the mists of obviousness of incoherent thought. Anyone still reading this drivel? Pontification is an unstoppable force of the irresistible nature of ignoring whatever anyone else may care and just keep blathering away until they get your point. Or just the enjoyment of hearing oneself talk. Pontification is not only a sacred freedom enshrined in the constitutions of our foremost nations as well as most public lavatory walls. It therefore cuts across all social and economic strata as the gift of education, asked for or not! I do not know your beliefs, Sir, but I believe in these sacred freedoms. I believe in the Constitution of the United States, the Magna Carta and the Rights Of Man. Give me pontification, or give me death!

Hear! Hear!

 

[MiTasol]

I looked through the report you provided a link for.
I see the mention that the propeller settings would allow for a maximum of 2600 RPM, but there is nothing in the actual speed runs that states that was the RPM being used.

As for Sakai and his statement of 345 MPH on overboost, what would that look like to an opposing pilot?
How about this: (from comments in SWP report)

Comments: Mention is made of a form of automatic boost control which limits
the manifold pressure to 35". Further mention should be made here of the fact
that there is a manual over ride which permits the manifold pressure to exceed
35" and obtain maximum boost from the engine. It is thought that this gives
the dense black smoke reported often in combat in connection with unusual
bursts of speed. In some instances this smoke has been attributed to injection
of some chemicals but it is felt that this is the result of of the manual over ride.

The section following this describes messing with the propeller pitch range to try to get the engine to wind up the way they were expecting.
The difficulty here is suggestive either of a propeller that is overly large or non-optimal gearing for the engine or an engine that isn't achieving the torque that it should be.

Or the prop rpm being limited deliberately so that the blade tips did not exceed the speed of sound and lose thrust. (and that may have been because of an incorrect reduction gear ratio or it also may have been deliberate to get the great fuel economy the A6M is famous for)

 

[Ivan1GFP]

Or the prop rpm being limited deliberately so that the blade tips did not exceed the speed of sound and lose thrust. (and that may have been because of an incorrect reduction gear ratio or it also may have been deliberate to get the great fuel economy the A6M is famous for)

You kind of need to know the rest of the context of the discussion.
The Akutan A6M2 was undergoing initial testing and the folks doing it were disappointed that they could not reach full engine RPM on the ground or even until the aircraft was well into its climbing speed. The initial propeller pitch limits were 25 degrees Min to 45 degrees Max. In order to get the engine to spin up faster, they changed the pitch limits to 17 degrees to 37 degrees, THEN they made the observation from a couple other recovered wrecks that the 25 - 45 actually was the normal pitch range and the propeller WASN'T out of adjustment.
If other aircraft of this type are having no problems with this propeller / configuration, then it is a pretty good indication that this particular aircraft's engine is under performing.

If this had been an initial design, then one can conclude that there was a mismatch in the Propeller Power Coefficient: Either the propeller is too big or the gearing to the engine is wrong so that the propeller is too difficult for the engine to turn but obviously this was not the case here.

It was another indication that the engine on this bird may have run but probably was not up to proper specifications.

 

[Engineman]

Of course, without all the tech manuals and instructions, it is likely that the engine and prop set-up was not all at optimum. However, the early counterweight/hydraulic HS copy prop was limited to 20 degrees of pitch range and that is insufficient for full rpm control of a high speed 300mph+ fighter. The small available pitch range means that the installed prop setting will have to be set slightly coarse for minimum pitch stationary on the ground. This setting will not be excessive as it will reduce rpm and power at Take-off. However, for carrier operations, the Wind over the deck will see the blade angle rapidly match the required rpm. The 25 degrees min blade angle setting roughly matches this.
The max blade angle of 45 degrees is not sufficient for high speeds, especially in dives, and this is reflected in the write-ups of overspeeding in dives.
So, overall the reported "problems" with not quite being able to achieve full rpm on the ground will match the limitations of the prop pitch range. However, the inability of achieving the full 2600 rpm in flight with an engine running well would indicate the prop pitch controller or its rigging was incorrectly set or malfunctioning at the 2600rpm selection.

Eng

 

[Ivan1GFP]

Of course, without all the tech manuals and instructions, it is likely that the engine and prop set-up was not all at optimum. However, the early counterweight/hydraulic HS copy prop was limited to 20 degrees of pitch range and that is insufficient for full rpm control of a high speed 300mph+ fighter. The small available pitch range means that the installed prop setting will have to be set slightly coarse for minimum pitch stationary on the ground. This setting will not be excessive as it will reduce rpm and power at Take-off. However, for carrier operations, the Wind over the deck will see the blade angle rapidly match the required rpm. The 25 degrees min blade angle setting roughly matches this.
The max blade angle of 45 degrees is not sufficient for high speeds, especially in dives, and this is reflected in the write-ups of overspeeding in dives.
So, overall the reported "problems" with not quite being able to achieve full rpm on the ground will match the limitations of the prop pitch range. However, the inability of achieving the full 2600 rpm in flight with an engine running well would indicate the prop pitch controller or its rigging was incorrectly set or malfunctioning at the 2600rpm selection.

Eng

The inability to reach full 2550 RPM on the ground is not unexpected. The inability to do this and come off the low pitch stop before achieving a sustained climb IS surprising.
Do you happen to remember which flight test report contained the write-up about over speeding in dives?
I am a bit curious because this may have been much less of an issue than one might think. The Vne of this aircraft was under 400 MPH IAS. It was eventually raised to 410 MPH IAS with a later version and even on the last production versions never exceeded 460 MPH IAS.

 

[Engineman]

The inability to reach full 2550 RPM on the ground is not unexpected. The inability to do this and come off the low pitch stop before achieving a sustained climb IS surprising.
Do you happen to remember which flight test report contained the write-up about over speeding in dives?
I am a bit curious because this may have been much less of an issue than one might think. The Vne of this aircraft was under 400 MPH IAS. It was eventually raised to 410 MPH IAS with a later version and even on the last production versions never exceeded 460 MPH IAS.

There are various quotes about max/achieved rpm on the ground in some of the downloads in this topic. The one quoting 2000rpm as the max stationary on the ground would seem quite low against achieving T/O power rating, but you have to assume the testing team were using the max rpm selection? What did the Japanese manuals say?
Quotes of 2500 rpm or so in the climb, again was max rpm selected?
As regards the prop pitch being on the "low pitch stop" in the climb, there is no pitch indication, so you can't tell if it is on/off the blade low pitch limit or if the controller is actually modulating the blade pitch to achieve the selected rpm or the incorrectly set-up selected rpm?
The quote I see about the overspeeding is 3000rpm above 300mph in the post#38 by MiTasol, "A6M evaluation.pdf"

Eng

 

[Ivan1GFP]

Post #10 in this thread is by GregP.
I tried a search on AGM evaluation and found pretty much nothing.
Can you confirm the source?
The comment about pitch stop was in the report.
No idea how testers were trying to run the engine.
Manual says +250 mm and 2550 RPM for Takeoff.