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View Full Version : N1K1, Ki-100, Ki-84, and why math is not predictive...



Gaston444
08-30-2010, 07:26 PM
Hello everyone.

I came accross this and would like to point it out as an example on how the wing's position relative to the prop can have large and unpredictable effects on performance, which makes it impossible to predict turn performance with just simplistic math formulations: Anyone can compare the following with the multiplicity of math-based game "speculations" that bear no relationship to reality:

Flight journal "Pacific fighters" collector edition 2010, p.74,:

"(On the N1K1, 1001 of near 1500 "George" built) It was probably faster than the Hellcat (It was vs -3s: N1K1: 650 km/h), but the turning performance and maneuverability were not very good. If you were rough with the stick, you could go into what the pilots called "autorotation". During this movement the aircraft would go out of control, or sometimes, it went into a spin. It turned in a way the pilot could not predict. For example, during an aerial melee over Manila with US fighters, a squadron mate of mine went into autorotation when our unit engaged them. His aircraft then went into a spin and crashed into the ground. In autorotation, you do not know what will happen, whether you will go into a spin, or flip over. It is totally unpredictable.

On the flaps: "They worked very well, however, in spite of them, handling the plane was still a problem. The combat flaps worked well in tight turns, and they would work smoothly. But, there were still handling problems with the aircraft. Ryoichi Yamada"



-These problems were apparently much reduced, or absent, on the low-wing N1K2.

If there are N1K1s in computer games, you can see how an inferior maneuverability to US types is certainly not what the math would predict... As one of the few mid-wing single engine monoplane fighters of WWII, one can see how even a few inches of wing position can change a lot of things, and the math predicts none of this...

Same with the Japanese's extensive, and prolonged, testing that concluded one Ki-100 could take on 3 Ki-84s in a dogfight and still have a good chance to win, to the point each of the Ki-84 pilots could repeat the same by switching aircraft...

So you really have to look beyond maths to get a meaningful picture...

Gaston

AndyJWest
08-30-2010, 07:53 PM
Gaston, how would you know what math predicts? You never use any...

BTW, I think Grumman might dispute your suggestion that the N1K1 was one of the few mid-wing single-engine monoplane fighters of WWII.

Should I even be feeding this troll?...

BillSwagger
08-30-2010, 08:38 PM
All he's saying is that math alone cannot predict the flight behavior of an aircraft, which would seem like common sense given other factors outside the realm of what the math measures. However, if the calculations take other considerations, such as stick force, vibrations, and propeller mechanics into the equation, then it can be mathematically calculated to predict behavior.
The problem is such calculations are often not used until after the plane is flown because factors like vibrations and stick forces aren't immediately apparent with out actually testing them.

"autorotation" is a new term for me in describing aircraft behavior. It seems something is lost in the translation of that journal. Is he describing torque or gyroscopic forces?

R_Target
08-30-2010, 08:41 PM
Originally posted by Gaston444:
one can see how even a few inches of wing position can change a lot of things,...

Most importantly, it changes the length of the landing gear by a few inches, which is why it was done.


Originally posted by Gaston444:
Same with the Japanese's extensive, and prolonged, testing that concluded one Ki-100 could take on 3 Ki-84s in a dogfight and still have a good chance to win, to the point each of the Ki-84 pilots could repeat the same by switching aircraft...

Can you share your source for this?

VW-IceFire
08-30-2010, 08:44 PM
Well... although I'm not really a math person myself, I fully believe that you can predict very accurately what the behavior of an aircraft is in real life down to a fairly fine degree. With one caveat... you need to know all of the various components to the equation. I imagine with computer modeling in the modern day we can probably do that... the guys working on the F-35 JSF project probably knew what the JSF was going to be like ages before one flew.

Nothing replaces going out and trying it out "the old fashioned way". In World War II... the situation was obviously far different than the modern day. It was almost as much a science as it was an art to determine if an airframe would be viable or not - not surprising the number of errors, mistakes, redesigns and so forth before even the best of the World War II aircraft were made viable.

AndyJWest
08-30-2010, 09:11 PM
BillSwagger asked:

"autorotation" is a new term for me in describing aircraft behavior. It seems something is lost in the translation of that journal. Is he describing torque or gyroscopic forces?


In aviation, the word autorotation is applied to operation of fixed-wing aircraft and rotary-wing aircraft. The word has significantly different meanings in each of these two applications.

In the operation of fixed-wing aircraft, autorotation is the name given to the manner in which an aircraft in a stall, or approaching the stall, displays a tendency to roll spontaneously to the right or left. A fixed-wing aircraft in a spin rolls continuously to the right or left, displaying the characteristic known as autorotation.
http://en.wikipedia.org/wiki/Autorotation
Gaston's quote seems to be using the term in its usually-accepted sense. Then again, Gaston is quoting someone else.

Gaston444
08-31-2010, 12:41 AM
"Autorotation" is exactly as the text was in the magazine: It is still on newstands now marked "display until November 1st"...

It is not a translation by me, but the pilot did likely speak in Japanese...

I have heard Robert Jonhson speak of autorotation for the P-47D, which is a similar-looking aircraft... I took it to mean the nose yaws opposite from the bank side as you implement the bank, as opposed to if it was the banking to the same side, which would then be a good thing: It clearly was meant as an abnormality, and may have no relation to the Japanese N1K1 issue anyway...

This to me explains why R. Johnson sometimes banked opposite his target's bank, especially to the right if the target banked left: A right bank might have turned him towards the left-going aircraft as he rolled 270 (but maybe he just wanted to avoid the "mushing" delay of a reversal, as he described himself, by carrying on a full roll circle in case the enemy reversed)...

I am also pretty sure that the P-47D, in its Razorback version at least, banked a bit slower to left and turned slightly slower to right... At least I thought it serious enough in several accounts to incorporate this in my simulation... The P-47D is one of the hardest WWII fighters out there to pin down on the "character" issue, and I don't claim to have everything right in my game...

I have to say I briefly forgot about mid-wing Grumman and Chance-Vought fighters(!), but they are shaped quite differently from the N1K1...

The 3-to-1 Ki-100 superiority over the Ki-84 is also pretty interesting and unexpected from a math point of view...

These are just examples: I don't claim to know what is going on here, but that and the FW-190A issue does illustrate nicely just how poor a "personality" picture maths can offer...

The "personality" of each WWII prop type is so marked, peculiar and unpredictable, that whenever I see a simulation with dozens upon dozens of types, I know it likely has no relationship at all to how these aircrafts really were like, except maybe for one or two of the best documented ones like the P-51... (And even then the reality of downthrottling is ignored)

I even heard that some simulations simply have variations of the same aircraft accross types, Il-2 being counted among those...

I actually think a serious simulation could hardly have less than one or two hundreds very detailed and useful pilot accounts for each type, in order to have even a very rough approximate idea of the combat "personality" of a WWII fighter type...

That should, in terms of realism, limit the plane set to about a dozen or so fighter types at most for all of WWII, and only one or two Japanese types at best...

Not that Il-2 is not very accurate in some particulars and figures, but for the rough, general character, the sheer number of types and sub-types alone tell the story in my eyes...

Gaston

P.S. Also the turn pitch pivot point being assumed to be at the center of the turn, like the 0 inertia roll reversals (which the designer of another simulation criticized), make the way the aircrafts move look very "crisp" in most simulations, and thus unrealistic, but that is another issue entirely. (It likely does introduce unrealistic tactics, since Il-2 tracks looks so completely unlike guncam footage...)

It should suffice to say that mathematics are way out of their depths to predict or capture the many major peculiarities of each prop fighter type's "personality" as a fighting weapon. (With all that messy churned-up air going around them...)

On the other hand, any pilot will tell you that once you have flown one type of WWII fighter, you can fly them all. Just don't expect them to survive combat in an unfamiliar type against people who ARE familiar with theirs: It's a whole other level then; precisely the one missing from these games imho...

G.

BillSwagger
08-31-2010, 01:43 AM
Originally posted by Gaston444:

This to me explains why R. Johnson sometimes banked opposite his target's bank, especially to the right if the target banked left: A right bank might have turned him towards the left-going aircraft as he rolled 270 (but maybe he just wanted to avoid the "mushing" delay of a reversal, as he described himself, by carrying on a full roll circle in case the enemy reversed)...

Actually rolling the opposite way of an enemies bank is a tactic used to help the faster moving pursuit plane make a similar change in direction with out over G ing his plane or blacking out (G-loc). Works in game if you try it, and usually favors the faster rolling planes. It also helps if the enemy reverses his roll in which case you don't have to counter your roll inertia and instead you either slow your roll or stop rolling so he banks into your path.



The 3-to-1 Ki-100 superiority over the Ki-84 is also pretty interesting and unexpected from a math point of view...


Depends on the math used and what factors it incorporated. According to the manual the Ki-84 has a maximum allowed acceleration of 5Gs. I'm not sure where the ki-100 ranks, but it might be considerably higher, in which case if factored in properly could determine why a 3 v 1 would still side with the 100 even in simulation.

Bill

R_Target
08-31-2010, 04:44 AM
Originally posted by Gaston444:
The 3-to-1 Ki-100 superiority over the Ki-84 is also pretty interesting and unexpected from a math point of view...

A source would be pretty interesting too.

Bremspropeller
08-31-2010, 06:22 AM
The "personality" of each WWII prop type is so marked, peculiar and unpredictable, that whenever I see a simulation with dozens upon dozens of types, I know it likely has no relationship at all to how these aircrafts really were like, except maybe for one or two of the best documented ones like the P-51... (And even then the reality of downthrottling is ignored)

That's minly because we're not watching a CFD-analysis (which would take a couple of weeks per aircraft), but playing a simplified game.

There's enough maths out there to very precisely tell how an aircraft flies - months before it's actually being built.
Unfortunately, this is pretty boring to watch and will propably not tell YOU anything useful at all, as you like to believe fiction over facts anyway.

JtD
08-31-2010, 01:46 PM
If you check how similar the N1K1 and N1K2 were you'll find that the differences were far more than "a few inches in wing position".

So I'd like to know why the wing position should be the deciding factor for the differences in handling.

Treetop64
08-31-2010, 03:00 PM
A bit late to the party, but:

Gaston, Dood...

Math can always be used - and is frequently used - to make predictions. If you have independent and dependent sets of data, no matter what the data is about, you can build a table and make a prediction (or projection).

The question is whether or not real world trends shift from the model.

R_Target
08-31-2010, 05:55 PM
Originally posted by JtD:
If you check how similar the N1K1 and N1K2 were you'll find that the differences were far more than "a few inches in wing position".

So I'd like to know why the wing position should be the deciding factor for the differences in handling.

My understanding was that lengthening the fuselage solved a few of the problems.

JtD
08-31-2010, 10:52 PM
That, a different tail and a different mass (distribution) would imo explain differences in handling very well.

But since Gaston knows it all and much better than anyone else on this world and he says it is all down to moving the wing a couple of inches, I'd like to know why the other changes had no effect.

(Not expecting a qualified answer.)

Kettenhunde
09-01-2010, 01:08 PM
wing position should be the deciding factor for the differences in handling.

Moment = Arm X Weight

Basic Stability and Control dictates the change the aerodynamic center of the wing and you change the aircraft Neutral Point. Which of course speaks to basic handling characteristics. All aircraft handling will alter as the CG's relationship to the NP changes including changes for consumables in flight.

Not that the tin foil hat theories that are the topic of the thread about basic aircraft performance are close to correct.

I am sure in a flush of goggling, JtD will post a treatise on why that is wrong.

I see it is the same "zoo". I won't waste anymore of my time. Good Luck.

JtD
09-01-2010, 03:53 PM
Arm for instance = distance between areodynamic center of the wing and CG.

Aerodynamic center of the wing changes.
CG changes.

Only aerodynamic center of the wing matters in Gastons world. Why?

Got it now, Kettenhunde?

Gaston444
09-02-2010, 02:18 AM
Originally posted by JtD:
Arm for instance = distance between areodynamic center of the wing and CG.

Aerodynamic center of the wing changes.
CG changes.

Only aerodynamic center of the wing matters in Gastons world. Why?

Got it now, Kettenhunde?


-Perhaps I shouldn't have insisted so much on the wing position, but you would have to concede it is by FAR the biggest change they CHOSE to make (and the most expensive and difficult one too)... I never said it was the ONLY change...

Changing the CG should have been easy to do while refining the N1K1 from the floatplane version, yet despite massively changing it compared to the N1K floatplane, including massively changing the entire cowling shape and lenght, they failed to improve on the handling until a low-wing re-design was done...

Besides, it is far from certain all the problems were removed on the N1K2: The Japanese N1K1 pilots do not bother to even mention this obviously important point, even though they likely flew the N1K2: The improvement is MY "supposition", strictly based on my part on a few fleeting US combat reports centering around known N1K2s battles...

I would consider this more solid by the time I reach a few dozen, concurring, combat accounts of confirmed N1K2 types by necessity of time and location.

Fat chance of even a few dozen relevant N1K2 accounts EVER surfacing... Which is exactly why you will NEVER find me modelling this thing for my boardgame...

See how REAL caution about accuracy works?

Another example of why any simulation designer should drop math "predictiveness", except for very narrow areas, if the "big" picture is to be even remotely relevant:

I know of one Ki-61-Ib pilot account describing how this supposedly slow-climber could out-zoom anything the US had until the P-38 was encountered, to the Ki-61's pilot's great shock... He described he could out-zoom the F6F easily and, in his words, "even the F4U was inferior to my Ki-61 in zoom, but with the P-38 I found myself in a predicament I had never faced before, as it stayed behind me even in the steepest climb as I tried to escape..."

Let me guess: Did math predict this outstanding and important tactical feature of early short-nosed Ki-61s?

My basic point is the N1K1 may have had very good qualities we are yet unaware of (like good stability and very good handling and zoom in high speed dives, making it an uniquely good BNZ aircraft as an example), but math utterly fails to predict one very basic point about the aircraft: That it was inferior and dangerous to fly in turn maneuverability compared to the likely US opposition: The F6F. Again, this very BASIC character point is totally absent from any calculations made then or since... How could a simulation chose math over this very basic point and claim a "percentage" of any sort in modelling accuracy?

The "personality" of a fighter aircraft, and its most peculiar salient points, are what should matter the most from any rational gameplay point of view: Isn't difference what makes these things interesting? Isn't it obvious the math morass used in simulations today simply levels everything into the same mediocre and untrue portrait?

In searching for my Ki-100 reference on this site, I came accross this old quote from JtD, a bit unfair given the age of it, but interesting in terms of unchanged assumptions compared to the pilot quotes above and those that will follow after...:

Posted October 21 2003: "- The Japanese did not produce a true 400mph prop
- fighter during the whole war (yes I know, the Ki-84
- did 427 mph after being refurbished and fueled with
- US fuel). In terms of manueverability and speed,
- the Hellcat, Ki-84, Ki-100 and N1K2J were probably
- pretty comparable. But even given the similarities
- in speed and performance, the Hellcat still held
- major andvantages especially in ruggedness and high
- altitude performance."


-Note the issue about the Ki-84 is now largely resolved, and it hopefully widely accepted now that it did indeed do near 700 km/h with Japanese fuels... Or around 420 MPH...

But compare these assumptions to what I provided before, and will provide now as requested:

"-OK, how about this for substantiated?: "Aeroplane" November 2005, "Ki-100 fighter Database" p. 61-77. (16 full pages on nothing but the Ki-100, with remarkable details, including on the development of the projected high-altitude turbo-charged variant)

Textual quote : P. 76:

"At these schools, the cream of the IJAAF's instructors, all very experienced combat pilots, would give their opinion on the new fighter (Ki-100). Almost all the Akeno instructors were graduates of the 54th Class of the Army Air Academy and also highly-qualified sentai commanders in their own right.

During March and April they would fly the Ki-100 in comparison tests against the most capable Japanese fighter then in service, the Ki-84 "Frank". After extensive testing the conclusion drawn by the Akeno pilots left little to the imagination.

In short, it stated that given equally skilled pilots, the Ki-100 would ALWAYS win a fight with the Ki-84 in any one-to-one combat. They further added that in a combat situation with up to three Ki-84s, the Ki-100 pilot could still develop the battle to his advantage.

The results of the evaluations at the Hitachi school were just as clear-cut. Captain Yasuro Mazaki and captain Toyoshia Komatso,also both graduates of the 54th class, developed the combat evaluation situations for the new fighter, and in order to give an unbiaised opinion of the aircraft, they swapped aircraft after each engagements and attempted combat from the opposite standpoint.

In the first combat the Ki-100 was flown against a single Ki-84 with the Ki-100 winning outright.

Mazaki stated: "When we entered combat with the Ki-100 taking the height advantage, the Ki-100 won every time. Even with an altitude disadvantage the Ki-100 could hold down the Ki-84 in two or three climbs during the exercise"

He added that the Ki-84 was "only superior to the Ki-100 in diving speed. The Ki-100 was much better in the turn and while climbing."



-I could not locate this more precisely quoted claim that the Ki-100 -"was so superior in turns as to be able to take on two P-51s at the same time", but it came directly from an experienced Japanese commander.

Against the P-51: "Aeroplane" p.77: "I learned how to take my fighter out of the firing line of the P-51 when being chased. I might never be able to shoot it down, but I was sure I would never be downed!"

P. 77. "The Ki-100 could fight equally against the P-51D"

P. 77. "The maneuverability of the Ki-100 was the best of the Army's frontline fighters with the exception of the Ki-43... And it had a strong advantage in that even less experienced pilots could fly it easily and fight with it."



-Note the defensive turning and climbing emphasis on all the above evaluations and encounters: The Ki-84 had a top speed of 690 km/h versus the Ki-100's top speed of probably less than 600-610 km/h(!).(P.68: "The Ki-100 was as fast as the current Ki-61-Id.")

Even if you discount, as I expect, the emphasis here on climbing and turn-fighting (made necessary in the real world warning contingencies by the usual altitude disadvange the Japanese had, making boom and zoom theories unuseable), you would still have to admit mathematics were of no help to predict the huge climb and turn performance gap between the Ki-100 and the Ki-84 as described here.

Now you know where the tin hat sits...

Gaston

AndyJWest
09-02-2010, 06:37 AM
Gaston, can you provide any evidence whatsoever to back up this statement:

My basic point is the N1K1 may have had very good qualities we are yet unaware of (like good stability and very good handling and zoom in high speed dives, making it an uniquely good BNZ aircraft as an example), but math utterly fails to predict one very basic point about the aircraft: That it was inferior and dangerous to fly in turn maneuverability compared to the likely US opposition: The F6F. Again, this very BASIC character point is totally absent from any calculations made then or since... How could a simulation chose math over this very basic point and claim a "percentage" of any sort in modelling accuracy?

By 'evidence' I mean evidence about the results of math calculations that were done at the time or have been since. You have asserted that no math could predict the N1K1's handling characteristics, but provide no evidence so far. Are you now claiming to have done extensive research into the design processes of WW2 Japanese aircraft design? If you haven't, and cannot therefore back up your claims, this statement needs to be recognised for what it is - garbage.

JtD
09-02-2010, 01:43 PM
Too tired to read and argue all that, but I'd like to know why it is now widely accepted that the Ki-84 did 400+mph in Japanese front line service (test report of a plane in field conditions would suffice).

I don't know why moving the wing a couple of inches when completely redesigning it would qualify as the by far largest change, but have it your way.

You know the differences between performance and handling and the physics & math behind predictions of either one?

R_Target
09-02-2010, 05:07 PM
Originally posted by Gaston444:
I would consider this more solid by the time I reach a few dozen, concurring, combat accounts of confirmed N1K2 types by necessity of time and location.

Fat chance of even a few dozen relevant N1K2 accounts EVER surfacing...

Henry Sakaida's Genda's Blade reconstructs the major combat actions of the Shiden-Kai down to the dozens of individual participants using reports from both sides. Really, you've gotta quit crutching on the internet and buy some books....


I know of one Ki-61-Ib pilot account describing how this supposedly slow-climber could out-zoom anything the US had until the P-38 was encountered, to the Ki-61's pilot's great shock... He described he could out-zoom the F6F easily and, in his words, "even the F4U was inferior to my Ki-61 in zoom, but with the P-38 I found myself in a predicament I had never faced before, as it stayed behind me even in the steepest climb as I tried to escape..."

For someone who constantly attempts to buttress their arguments with weight of opinion, you seem to have no problem with odd exceptions when it suits you.


but math utterly fails to predict one very basic point about the aircraft: That it was inferior and dangerous to fly in turn maneuverability compared to the likely US opposition: The F6F.

More silliness. The N1K2 was a highly capable plane, and was well liked by it's pilots.


The "personality" of a fighter aircraft, and its most peculiar salient points, are what should matter the most from any rational gameplay point of view: Isn't difference what makes these things interesting? Isn't it obvious the math morass used in simulations today simply levels everything into the same mediocre and untrue portrait?

This might be an interesting discussion if you actually owned and flew IL2.


-Note the issue about the Ki-84 is now largely resolved, and it hopefully widely accepted now that it did indeed do near 700 km/h with Japanese fuels... Or around 420 MPH...

Lol, JtD was right the first and second time


"Aeroplane" November 2005, "Ki-100 fighter Database"

Thanks for the source.


the usual altitude disadvange the Japanese had, making boom and zoom theories unuseable),

Incorrect. Dive-n-climb gunnery runs were what 343rd Air Group trained for in their N1K2's and successfully used in their interceptions of Allied planes.


Now you know where the tin hat sits...

Gaston

I know where it belongs.... http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

AndyJWest
09-02-2010, 09:12 PM
Common characteristics of cranks

The second book of the philosopher and popular author Martin Gardner was a study of crank beliefs, Fads and Fallacies in the Name of Science. More recently, the mathematician Underwood Dudley has written a series of books on mathematical cranks, including The Trisectors, Mathematical Cranks, and Numerology: Or, What Pythagoras Wrought. And in a 1992 UseNet post, the mathematician John Baez humorously proposed a "checklist", the Crackpot index, intended to "diagnose" cranky beliefs regarding contemporary physics.[2]

According to these authors, virtually universal characteristics of cranks include:

1. Cranks overestimate their own knowledge and ability, and underestimate that of acknowledged experts.
2. Cranks insist that their alleged discoveries are urgently important.
3. Cranks rarely, if ever, acknowledge any error, no matter how trivial.
4. Cranks love to talk about their own beliefs, often in inappropriate social situations, but they tend to be bad listeners, and often appear to be uninterested in anyone else's experience or opinions.

Some cranks exhibit a lack of academic achievement, in which case they typically assert that academic training in the subject of their crank belief is not only unnecessary for discovering "the truth", but actively harmful because they believe it "poisons" the minds by teaching falsehoods. Others greatly exaggerate their personal achievements, and may insist that some alleged achievement in some entirely unrelated area of human endeavor implies that their cranky opinion should be taken seriously.

Some cranks claim vast knowledge of any relevant literature, while others claim that familiarity with previous work is entirely unnecessary; regardless, cranks inevitably reveal that whether or not they believe themselves to be knowledgeable concerning relevant matters of fact, mainstream opinion, or previous work, they are not in fact well-informed concerning the topic of their belief.

In addition, many cranks:

1. seriously misunderstand the mainstream opinion to which they believe that they are objecting,
2. stress that they have been working out their ideas for many decades, and claim that this fact alone entails that their belief cannot be dismissed as resting upon some simple error,
3. compare themselves with Galileo or Copernicus, implying that the mere unpopularity of some belief is in itself evidence of plausibility,
4. claim that their ideas are being suppressed, typically by secret intelligence organizations, mainstream science, powerful business interests, or other groups which, they allege, are terrified by the possibility of their revolutionary insights becoming widely known,
5. appear to regard themselves as persons of unique historical importance.

Cranks who contradict some mainstream opinion in some highly technical field, such as mathematics or physics, almost always:

1. exhibit a marked lack of technical ability,
2. misunderstand or fail to use standard notation and terminology,
3. ignore fine distinctions which are essential to correctly understand mainstream belief.

That is, cranks tend to ignore any previous insights which have been proven by experience to facilitate discussion and analysis of the topic of their cranky claims; indeed, they often assert that these innovations obscure rather than clarify the situation.[3]

In addition, cranky scientific "theories" do not in fact qualify as theories as this term is commonly understood within science. For example, crank "theories" in physics typically fail to result in testable predictions, which makes them unfalsifiable and hence unscientific. Or the crank may present their ideas in such a confused manner that it is impossible to determine what they are actually claiming.

Perhaps surprisingly, many cranks may appear quite normal when they are not passionately expounding their cranky belief, and they may even be successful in careers unrelated to their cranky belief. Others can (charitably) be characterized as underachievers in all walks of life.

http://en.wikipedia.org/wiki/Crank_%28person%29

VW-IceFire
09-02-2010, 09:20 PM
Originally posted by Gaston444:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by JtD:
Arm for instance = distance between areodynamic center of the wing and CG.

Aerodynamic center of the wing changes.
CG changes.

Only aerodynamic center of the wing matters in Gastons world. Why?

Got it now, Kettenhunde?


-Perhaps I shouldn't have insisted so much on the wing position, but you would have to concede it is by FAR the biggest change they CHOSE to make (and the most expensive and difficult one too)... I never said it was the ONLY change...

Changing the CG should have been easy to do while refining the N1K1 from the floatplane version, yet despite massively changing it compared to the N1K floatplane, including massively changing the entire cowling shape and lenght, they failed to improve on the handling until a low-wing re-design was done...

Besides, it is far from certain all the problems were removed on the N1K2: The Japanese N1K1 pilots do not bother to even mention this obviously important point, even though they likely flew the N1K2: The improvement is MY "supposition", strictly based on my part on a few fleeting US combat reports centering around known N1K2s battles...

I would consider this more solid by the time I reach a few dozen, concurring, combat accounts of confirmed N1K2 types by necessity of time and location.

Fat chance of even a few dozen relevant N1K2 accounts EVER surfacing... Which is exactly why you will NEVER find me modelling this thing for my boardgame...

See how REAL caution about accuracy works?

Another example of why any simulation designer should drop math "predictiveness", except for very narrow areas, if the "big" picture is to be even remotely relevant:

I know of one Ki-61-Ib pilot account describing how this supposedly slow-climber could out-zoom anything the US had until the P-38 was encountered, to the Ki-61's pilot's great shock... He described he could out-zoom the F6F easily and, in his words, "even the F4U was inferior to my Ki-61 in zoom, but with the P-38 I found myself in a predicament I had never faced before, as it stayed behind me even in the steepest climb as I tried to escape..."

Let me guess: Did math predict this outstanding and important tactical feature of early short-nosed Ki-61s?

My basic point is the N1K1 may have had very good qualities we are yet unaware of (like good stability and very good handling and zoom in high speed dives, making it an uniquely good BNZ aircraft as an example), but math utterly fails to predict one very basic point about the aircraft: That it was inferior and dangerous to fly in turn maneuverability compared to the likely US opposition: The F6F. Again, this very BASIC character point is totally absent from any calculations made then or since... How could a simulation chose math over this very basic point and claim a "percentage" of any sort in modelling accuracy?

The "personality" of a fighter aircraft, and its most peculiar salient points, are what should matter the most from any rational gameplay point of view: Isn't difference what makes these things interesting? Isn't it obvious the math morass used in simulations today simply levels everything into the same mediocre and untrue portrait?

In searching for my Ki-100 reference on this site, I came accross this old quote from JtD, a bit unfair given the age of it, but interesting in terms of unchanged assumptions compared to the pilot quotes above and those that will follow after...:

Posted October 21 2003: "- The Japanese did not produce a true 400mph prop
- fighter during the whole war (yes I know, the Ki-84
- did 427 mph after being refurbished and fueled with
- US fuel). In terms of manueverability and speed,
- the Hellcat, Ki-84, Ki-100 and N1K2J were probably
- pretty comparable. But even given the similarities
- in speed and performance, the Hellcat still held
- major andvantages especially in ruggedness and high
- altitude performance."


-Note the issue about the Ki-84 is now largely resolved, and it hopefully widely accepted now that it did indeed do near 700 km/h with Japanese fuels... Or around 420 MPH...

But compare these assumptions to what I provided before, and will provide now as requested:

"-OK, how about this for substantiated?: "Aeroplane" November 2005, "Ki-100 fighter Database" p. 61-77. (16 full pages on nothing but the Ki-100, with remarkable details, including on the development of the projected high-altitude turbo-charged variant)

Textual quote : P. 76:

"At these schools, the cream of the IJAAF's instructors, all very experienced combat pilots, would give their opinion on the new fighter (Ki-100). Almost all the Akeno instructors were graduates of the 54th Class of the Army Air Academy and also highly-qualified sentai commanders in their own right.

During March and April they would fly the Ki-100 in comparison tests against the most capable Japanese fighter then in service, the Ki-84 "Frank". After extensive testing the conclusion drawn by the Akeno pilots left little to the imagination.

In short, it stated that given equally skilled pilots, the Ki-100 would ALWAYS win a fight with the Ki-84 in any one-to-one combat. They further added that in a combat situation with up to three Ki-84s, the Ki-100 pilot could still develop the battle to his advantage.

The results of the evaluations at the Hitachi school were just as clear-cut. Captain Yasuro Mazaki and captain Toyoshia Komatso,also both graduates of the 54th class, developed the combat evaluation situations for the new fighter, and in order to give an unbiaised opinion of the aircraft, they swapped aircraft after each engagements and attempted combat from the opposite standpoint.

In the first combat the Ki-100 was flown against a single Ki-84 with the Ki-100 winning outright.

Mazaki stated: "When we entered combat with the Ki-100 taking the height advantage, the Ki-100 won every time. Even with an altitude disadvantage the Ki-100 could hold down the Ki-84 in two or three climbs during the exercise"

He added that the Ki-84 was "only superior to the Ki-100 in diving speed. The Ki-100 was much better in the turn and while climbing."



-I could not locate this more precisely quoted claim that the Ki-100 -"was so superior in turns as to be able to take on two P-51s at the same time", but it came directly from an experienced Japanese commander.

Against the P-51: "Aeroplane" p.77: "I learned how to take my fighter out of the firing line of the P-51 when being chased. I might never be able to shoot it down, but I was sure I would never be downed!"

P. 77. "The Ki-100 could fight equally against the P-51D"

P. 77. "The maneuverability of the Ki-100 was the best of the Army's frontline fighters with the exception of the Ki-43... And it had a strong advantage in that even less experienced pilots could fly it easily and fight with it."



-Note the defensive turning and climbing emphasis on all the above evaluations and encounters: The Ki-84 had a top speed of 690 km/h versus the Ki-100's top speed of probably less than 600-610 km/h(!).(P.68: "The Ki-100 was as fast as the current Ki-61-Id.")

Even if you discount, as I expect, the emphasis here on climbing and turn-fighting (made necessary in the real world warning contingencies by the usual altitude disadvange the Japanese had, making boom and zoom theories unuseable), you would still have to admit mathematics were of no help to predict the huge climb and turn performance gap between the Ki-100 and the Ki-84 as described here.

Now you know where the tin hat sits...

Gaston </div></BLOCKQUOTE>
So... what are you trying to say? The Ki-100 doesn't have nearly as much horsepower as the Ki-84 does. Also we know that the Ki-61 had a clean design that lent itself to adequate zoom climbs. This mostly translated into the Ki-100 and so while I don't know the drag co-efficient I do know that I can stay with more powerful aircraft in a Ki-100 during a zoom climb with not too much trouble.

The trouble with the quotes you have is that you're taking a lot of context out that is VERY important. Climb may mean zoom climb since the Ki-84 does have a better climb... but pilots often talk about zoom climb (as climb) because it's more usable in combat.

Also ... for all of the talk of math. I don't see very much... ?

Gaston444
09-02-2010, 11:57 PM
Why not explain what the context IS, rather than say it is out of context, for a change?

The overall point is, I have been reading this and other boards since 2002, 8 years, and nothing I have seen here or elsewhere, that describes even the most basic trait of WWII fighter aircrafts, has ever provided the most fleeting unexpected insight into what was perfectly obvious to experienced combat pilots...

I would even say generally that simplistic math evaluations of these aircraft's combat ability is worth a lot less than zero: Almost every time a real WWII front-line combat pilot speaks of his experience, it sends massively elaborate IL-2 threads crashing into the dusbin, even when the threads themselves informed me of these accounts... The funny thing is, simmers in general seem completely oblivious to the glaring contradictions, even when Rall's infamous "Saber vs Floret" metaphor intends to make the issue crystal clear for future generations... (He obviously overestimated their ability to... Ahem... "Synthetize" a point made for clarity...)

To witness:

-Until I read the Ki-100 test displayed here, no one here had given me the slightest indication that it was considered to be worth two or three Ki-84s in a dogfight by the Japanese themselves...

If maths cannot predict that, what the HELL can it predict?

-Until I read that the N1K1 had trouble with autorotation, no one here has ever noted that its maneuverability was likely very much an inferior point, thus a likely boom and zoomer...

-Until I read this ONE account by an experienced Ki-61 pilot, nobody here has ever indicated they thought it could out-zoom climb the F6F, much less the F4U...

Quote R_Target: "Incorrect. Dive-n-climb gunnery runs were what 343rd Air Group trained for in their N1K2's and successfully used in their interceptions of Allied planes."

-Thanks for this, as it indicates to me the HORIZONTAL maneuverability problems were NOT solved by the N1K2 variant, and thus may indeed have had little to do with the wing's position...

See, I can CONCEDE points: A very unfamiliar feeling to many here, you'll note (shades of an ever-decreasing LEFT "vertical" loop comes to mind http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif)...

When the Japanese use an aircraft in boom and zoom tactics, it is a sign they don't much like its horizontal performance... (Note how I speculated the N1K might be good in boom and zoom, since the maneuverability was in a significant way crap...)

-I won't insist too much on the pathetic upside-down FW-190A conclusions, if we count ONLY front-line combat experience... Not! (As opposed to E. Brown and the US Navy's turn under the tin hat...)

-I won't go too deeply either into the brilliant "math prediction" that the Ki-67 medium bomber can indeed out-turn some of the Japanese's own single-engine fighters (Gunston) (which likely means the N1K1 and the Ki-84 at least, if the above Ki-100 vs Ki-84 test is any guide)...

In the same vein, the Tu-2 empty is also said to out-turn most of the Soviets single-engine fighters. If maths were so predictive, how come we don't hear the same about the Pe-2?

I am all ears for the math explanation behind THAT...

The power, empty weight and wing area of the Ki-67 are only marginally different from those of the B-25 (Ki-67 span is a bit larger): Does that mean we have to expect the B-25 to out-turn Ki-84s or N1K1s now?

In the world of all-seeing maths it does seem to mean that... You'll have to excuse me for being a bit sceptical.

Gaston

JtD
09-03-2010, 12:18 AM
Regarding turning, look at the stall speed. The plane with the lower stall speed will always find conditions where it can outturn planes with a higher stall speed in a low speed turn.

Look up bomber stall speeds and compare them to fighter stall speeds.

BillSwagger
09-03-2010, 01:00 AM
Originally posted by Gaston444:


In the world of all-seeing maths it does seem to mean that... You'll have to excuse me for being a bit sceptical.


Nothing wrong with skepticism, and anyone who is a fan of the history of aviation knows that math is not the end all to predicting aircraft behavior.
The "math" on its face is very reliable. "Math" should alleviate skepticism because it applies the same rules over a vast combination of data and prototypes, or what ever the engineer is designing. Its easy to compare wing areas, weight, power and drag ratios, but anything the math does not recognize will cause an error in the prediction of the behavior. The math would not recognize the variables that are left out of the calculation. From that stand point its easy and reasonable to think that "math" can not be a 100 percent predictor.

"Here you go, get on board. It will fly because my math says so."

How many of you would get on a plane that had never been test flown and rely strictly on the math as a predictor?

I don't think anyone here disagrees with that.

BillSwagger
09-03-2010, 01:07 AM
Originally posted by JtD:
Regarding turning, look at the stall speed. The plane with the lower stall speed will always find conditions where it can outturn planes with a higher stall speed in a low speed turn.

Look up bomber stall speeds and compare them to fighter stall speeds.

Yes but what if the cockpit is cramped as to prevent one plane from efficiently using all of its elevator throw.
On paper it makes a tighter circle, but in practice it could become quite a chore, enough to effect the actual performance.
This is a hypothetical, but something that only math would predict if it were considered in the calculation. Analyzing wing area and weight would not draw that conclusion, which is what i think Gaston is trying to point out.


Bill

FatCat_99
09-03-2010, 01:47 AM
Originally posted by BillSwagger:
Nothing wrong with skepticism, and anyone who is a fan of the history of aviation knows that math is not the end all to predicting aircraft behavior.
That's true but in simulation games we are not predicting performance, we are simulating known performance of the plane and that is very different from predicting performance of new design. Math behind simulation is pretty good and it is proven in practice. All of the current theories were tested and compared with real results, naturally, there is no 100% match between calculations and tests but test result are not the same all the time either. What matters for simulation is that calculations are reasonably close.



"Here you go, get on board. It will fly because my math says so."

How many of you would get on a plane that had never been test flown and rely strictly on the math as a predictor?

I don't think anyone here disagrees with that.
Each and every plane was once flown by a guy/girl who trusted math and physics. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

FC

BillSwagger
09-03-2010, 04:55 AM
http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

As for modeling planes in a game, i think publishers end up going with what is popular. I can't speak for Il2, it just seems like if the majority of your fan base likes Plane A, Plane B, and Plane C then they are likely to be the more superior planes in the game. It isn't that they aren't accurate, but since they might be the focus then they end up getting more attention. If more people fly them, then more people complain...and so on.
As a sim user i also look at other factors like playability, replay value, aside from accuracy.
The math always seems to come up because its the only concrete way to base anything off of.
Actually engineering airplanes is much more complex and involves a much wider range of math, much more complex than video game programming.
Seems like i'm stating the obvious, but for that reason i think people who program planes into a video game also use other methods of research.

I think Gaston was trying to touch on that, but since he has already exhausted this audience in previous threads the relevant things he says are quickly disputed.

Bill

Kettenhunde
09-03-2010, 01:26 PM
The plane with the lower stall speed will always find conditions where it can outturn planes with a higher stall speed in a low speed turn.


Just as the airplane with the higher speed will always find conditions it can out turn the slower one.

megalopsuche
09-05-2010, 10:29 AM
Should I even be feeding this troll?...

No! Here comes another 40 page thread.

VW-IceFire
09-05-2010, 12:17 PM
Originally posted by Gaston444:
Why not explain what the context IS, rather than say it is out of context, for a change?

The overall point is, I have been reading this and other boards since 2002, 8 years, and nothing I have seen here or elsewhere, that describes even the most basic trait of WWII fighter aircrafts, has ever provided the most fleeting unexpected insight into what was perfectly obvious to experienced combat pilots...

I would even say generally that simplistic math evaluations of these aircraft's combat ability is worth a lot less than zero: Almost every time a real WWII front-line combat pilot speaks of his experience, it sends massively elaborate IL-2 threads crashing into the dusbin, even when the threads themselves informed me of these accounts... The funny thing is, simmers in general seem completely oblivious to the glaring contradictions, even when Rall's infamous "Saber vs Floret" metaphor intends to make the issue crystal clear for future generations... (He obviously overestimated their ability to... Ahem... "Synthetize" a point made for clarity...)

To witness:

-Until I read the Ki-100 test displayed here, no one here had given me the slightest indication that it was considered to be worth two or three Ki-84s in a dogfight by the Japanese themselves...

If maths cannot predict that, what the HELL can it predict?

-Until I read that the N1K1 had trouble with autorotation, no one here has ever noted that its maneuverability was likely very much an inferior point, thus a likely boom and zoomer...

-Until I read this ONE account by an experienced Ki-61 pilot, nobody here has ever indicated they thought it could out-zoom climb the F6F, much less the F4U...

Quote R_Target: "Incorrect. Dive-n-climb gunnery runs were what 343rd Air Group trained for in their N1K2's and successfully used in their interceptions of Allied planes."

-Thanks for this, as it indicates to me the HORIZONTAL maneuverability problems were NOT solved by the N1K2 variant, and thus may indeed have had little to do with the wing's position...

See, I can CONCEDE points: A very unfamiliar feeling to many here, you'll note (shades of an ever-decreasing LEFT "vertical" loop comes to mind http://forums.ubi.com/groupee_common/emoticons/icon_rolleyes.gif)...

When the Japanese use an aircraft in boom and zoom tactics, it is a sign they don't much like its horizontal performance... (Note how I speculated the N1K might be good in boom and zoom, since the maneuverability was in a significant way crap...)

-I won't insist too much on the pathetic upside-down FW-190A conclusions, if we count ONLY front-line combat experience... Not! (As opposed to E. Brown and the US Navy's turn under the tin hat...)

-I won't go too deeply either into the brilliant "math prediction" that the Ki-67 medium bomber can indeed out-turn some of the Japanese's own single-engine fighters (Gunston) (which likely means the N1K1 and the Ki-84 at least, if the above Ki-100 vs Ki-84 test is any guide)...

In the same vein, the Tu-2 empty is also said to out-turn most of the Soviets single-engine fighters. If maths were so predictive, how come we don't hear the same about the Pe-2?

I am all ears for the math explanation behind THAT...

The power, empty weight and wing area of the Ki-67 are only marginally different from those of the B-25 (Ki-67 span is a bit larger): Does that mean we have to expect the B-25 to out-turn Ki-84s or N1K1s now?

In the world of all-seeing maths it does seem to mean that... You'll have to excuse me for being a bit sceptical.

Gaston
You're all over the place and you keep mentioning math but there's no math in your posts.

Historical context - means quite a few things. I could write a whole book on it. But if you look at some basic pilot comments re: the Ki-100 versus Ki-84 and P-51 performance you see things like the Ki-100 having excellent climb. Well Japanese pilots and most combat pilots usually talk about what is "usable" in combat... so what they really mean is zoom climb. The context of the Ki-100 versus Ki-84 trial is unknown as far as I know. We're missing all kinds of information:

- limitations of the test
- condition of the aircraft involved
- altitude at beginning and end of the test

If they did a straight stall fight test then yeah the Ki-100 would probably win. Point is: we don't know the full context of the test or the climate in which the comments were made in. Picking bits and pieces of history often lead to misunderstandings. Just like interpreting aircraft performances with only certain criteria lead to large holes in information.

Quite a few pilot interviews contradict each other because it's based on memory and experiences often from the heat of combat. Memories get fuzzy. Results are skewed either intentionally or unintentionally to make one/side/nation/whatever feel better about itself. Aircraft that were tested by opposing nations often don't know what the factory ideal settings are for the planes so they guess at how they work (i.e. the captured Zero that had the fuel system installed incorrectly leading to negative G cut out in dives - not a problem for factory produced Zeros).

Where is your math and what on earth are you really talking about?

M_Gunz
09-05-2010, 04:05 PM
Mathematical modeling does not include the pilots. Incorrect use of modeling will not include the situation. So it is easy for an agenda-driven troll to strongly misrepresent any model in comparison to troll-interpreted historic accounts.

IL2 does not say that Karhila is wrong and I am sure it does not say that Ki-100 is a loser, no matter how many losers can't get the best out of the IL2 model.

Raaaid please notice! If you hook the leads of a good size speaker to a diode bridge and point it at a sound source, you get rippled DC out. Using a whiner as the sound source you will have some _small_ but free energy. The thing is that if the whiner finds out it is doing something useful, it will probably quit.

BillSwagger
09-05-2010, 05:52 PM
Originally posted by VW-IceFire:
Historical context - means quite a few things. I could write a whole book on it. But if you look at some basic pilot comments re: the Ki-100 versus Ki-84 and P-51 performance you see things like the Ki-100 having excellent climb. Well Japanese pilots and most combat pilots usually talk about what is "usable" in combat... so what they really mean is zoom climb.


Aren't assumption like these misleading? Isn't that the problem with using pilot combat reports to begin with?
I don't entirely disagree, but what do you say about a plane like the P-47, notorious for its slow climb, yet praised for its zoom performance?
or a 109, notorious for its climb ability yet in some cases out matched in zoom performance?

The P-51 was not known for its extended climbs either. I think speed has a direct correlation with zoom performance.
A slower plane does not usually out zoom a faster plane unless there is a hugely disproportionate difference in thrust to weight.

"....so what they really mean is zoom climb" is not something i could conclude with out more examples.

The reason i say that is because there might be conditions where it is true. Obviously, the start speed is going to dictate the zoom performance the same way it would dictate dive performance. If anyone dare attempt to formulate comparisons, i think you might see that start speed will effect the way each plane performs in a zoom climb.

i would also mention that typical combat tactics didn't involve climbing to escape by the allied planes. It was dive, separate and then extend.

On another note:

I was looking at a test for the Allison (P-40N) for level speed and climb.
The interesting thing is that the full throttle height on the climb test is about 7000ft, and on the level speed test it was 9200ft. The engine was run at war emergency power, equivalent to 57" boost, on both tests.
The test mentions the climate was hot and dry desert conditions. The only thing that differentiates the two tests is the days they were tested.
I know the reason for these differences, my point is that even tests can be somewhat limited to making comparisons over a broad range of aircraft. You couldn't even make the same conclusions using the same aircraft if they were tested on different days. I would think the aircraft in question would have better climb performance if the FTH were closer to 9000ft than 7000ft, or that level speed performance would be hampered if FTH were closer to 6500 feet.

The interesting thing about some Japanese tests is that they'd perform mock dogfights with the planes in question, swap pilots, and repeat. Usually they get to some sort of conclusion that one plane is superior to the other because despite pilot ability, the one plane consistently outperforms the other in combat.

M_Gunz
09-06-2010, 01:58 AM
Hey Bill, where did you find a test where the P-40N has a full throttle height of 7,000 feet?

Also at full speed you get ram air effect while best climb is nowhere near that fast.

VW-IceFire
09-06-2010, 08:17 AM
Originally posted by BillSwagger:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by VW-IceFire:
Historical context - means quite a few things. I could write a whole book on it. But if you look at some basic pilot comments re: the Ki-100 versus Ki-84 and P-51 performance you see things like the Ki-100 having excellent climb. Well Japanese pilots and most combat pilots usually talk about what is "usable" in combat... so what they really mean is zoom climb.


Aren't assumption like these misleading? Isn't that the problem with using pilot combat reports to begin with?
I don't entirely disagree, but what do you say about a plane like the P-47, notorious for its slow climb, yet praised for its zoom performance?
or a 109, notorious for its climb ability yet in some cases out matched in zoom performance?
</div></BLOCKQUOTE>
Using pilot reports, particularly those from combat are definitely a problem. Everything is situational and combat is so extremely stressful I'm sure that memories are totally contorted.

And yes it may be misleading because I haven't covered or researched nearly enough - my point was that we're missing quite a bit of context and he wanted an example. So he got one http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif But I'm probably not being very well understood... so I tried.

Oh... and I would be interested in the P-40N test. I'm still hoping that we have that as a flyable P-40 variant sometime. That'd be great!

M_Gunz
09-06-2010, 11:24 AM
I just wonder what special sub-variant had FTH below 10,000 ft when -most- P-40N's had a ceiling from 31,000 to 38,000 ft and achieved top speed at 15,000+ ft. Even the B and C models could fight up to 20,000-21,000 ft. But the N models did vary quite a lot as to weight, armament, or which Allison engine was used.

Sillius_Sodus
09-06-2010, 12:23 PM
http://i218.photobucket.com/albums/cc53/Sillius_Sodus/Screenshots/2564366072_be1e73783b_z.jpg

JtD
09-06-2010, 12:30 PM
FTH of about 15000 at WEP with 57" boost? I'd expect lower power settings, like Military around 52".

M_Gunz
09-06-2010, 06:30 PM
However top speed is attained. I don't find so many charts with FTH labeled. Would that be where the engine can no longer maintain full boost then?

WTE_Galway
09-06-2010, 10:19 PM
Originally posted by M_Gunz:
However top speed is attained. I don't find so many charts with FTH labeled. Would that be where the engine can no longer maintain full boost then?

FTH is the density altitude at which the specified power is available with full throttle set.

Commonly you want this figure for working out best endurance which in theory should be obtained flying Vh at FTH. Note that in the real world we are generally more interested in maximum range rather than how long we can stay airborne so max endurance isn't normally a big issue unless we are in a holding pattern and low on fuel.

As an example if your engine maximum recommended continuous power is 75% and you produce 75% of maximum horsepower with full throttle set at 7000 meters density altitude then your FTH for maximum continuous power is 7000 meters.

Clearly for a normally aspirated engine FTH for maximum takeoff power is sea level.

BillSwagger
09-07-2010, 03:07 AM
Originally posted by M_Gunz:
However top speed is attained. I don't find so many charts with FTH labeled. Would that be where the engine can no longer maintain full boost then?

yeah, the charts on pearls site (http://www.raafwarbirds.org.au/targetvraaf/p40_archive/pdfs/P40N%20RAAF%20A29-412%20&%20418%20Test.pdf) indicate the full throttle height labeled at 6800ft for climb and 9200ft for level speed using a WEP setting of 57". starts at page 29.
The differences could be related to ram air pressure. This simply means the engine could not hold that WEP manifold setting above those heights.

Military power settings place FTH closer to 15000ft.

This seems to be a trend amongst the Allison engines when using higher boost settings, although General Motors also cleared the engine for 60" of boost when it was reported to have been pushing 72" in the field.
The history here is a bit questionable because most pilots could only achieve higher boost pressures above 12,000ft by over revving the engine and keeping the plane fast.

My main point was the difference in FTH on two separate tests, but now that you mention it, it could be because of RAM air.


Bill

WholeHawg
09-08-2010, 10:39 AM
Math can predict everything. If its not giving your the correct answer then your model/formulas are at fault not the math it self.

M_Gunz
09-08-2010, 07:16 PM
Or at least math can be used to predict -physical- movement pretty close but no guarantee any one person can. And it's no good for predicting -pilot- performance.

Relying on combat accounts from one side doesn't tell who the enemy pilot(s)(and crew) was/were or what their situation was except to approximations based on only an outside view.

Math is not good for telling if a pilot is going to use a certain tactic and flying style only or be able to react and switch to counter-tactics, only hoping he knows more than one. The right tactics are worth more than the best flying that only knows one or two basic styles. It's worth more than 10% 'better' plane.
Yet time and again I read that P-51's shot down X number planes and FW's shot down Z number planes, as if the plane chose the tactics let alone situational advantages and disadvantages or flew itself and made the shots. Try turning hard when you're going too fast. Couple that with a turn-fixated dweeb and you'll find out how rotten the FM is pretty quickly.

In the American Experience WWII volume there's a story about USAAF in North Africa and how Fighter Command started. Because in the beginning, the ground commanders had control of the fighters and spread them all out in assigned areas along the front, in small groups. And the LW would send about 4x as many in formation and tear them up. The pilots got together and sent a leader (famous pilot but I forget just who) to see Eisenhower and Fighter Command was born, the USAAF was no longer staked out for meat and the easy kills ended right there.
Now if I pick combat reports or combat results from that first period and assigned it all to the *planes* it is going to differ from the same 'correct procedure' applied to after the formation of USAAF Fighter Comand -- but still the same planes and the same pilots. Picking all of them and blending the whole campaign still isn't more than a fraction about *the planes* since the tactics and situation are worth more than the aircraft performance. Of course you have to understand what you;re reading to avoid falling into the old 'the plane did' trap.