109's kill ratio (all variants from B to K)

[HoHun]

Hi Charon,

>Nor did the Junkers patent show the variable exhaust mechanisms that made the process effective.

The point is that the Messerschmitt design shows just this variable exhaust mechanism that made the process "effective".

Regards,

Henning (HoHun)

[niklas]

.... and which worked in manoevering flights also, opening a bit, like an automatic combat flap (split type)  

niklas

[Charon]

The point is that the Messerschmitt design shows just this variable exhaust mechanism that made the process "effective".

... as long as all the other elements in the duct design were effective as well. My understanding is that this effect involves a successfully functioning system of elements from the inlet, to the internal duct design and demensions to the exhaust mechanism.

"In the case of the Mustang, the duct volume was larger and flow instability more violent, creating an unacceptable vibration and rumble. Resourceful engineers at North American, working with wind tunnel models, overcame the problem by lowering the intake upper lip below the wing surface boundary layer, thus beginning a new upper duct surface. In this design, the flow expanded gradually as the duct velocity decreased, and the pressure at the radiator face was reasonably uniform. This permitted the appropriate closure of the exit with a temperature-controlled power actuator, and a minimum pressure drop across the radiator consistent with efficient radiator function and cooling demand...

"It seems that most other contemporary airplanes attempting to take advantage of the Meredith Effect failed for one reason or another to combine an efficient duct system with a properly designed and regulated exit-closing mechanism and did not develop the energy recovery inherent in the Meredith method. They generally used 10 percent or more of their power available at high speed to overcome cooling drag. A notable exception was the DeHavilland Mosquito multi-purpose plane with the same Rolls-Royce engines and which used a wing leading edge radiator mounting with a short and direct inlet duct. The controllable exit opening had a minimum area little more than half that of the Spitfire, and while it was a larger two-engine airplane, it had a speed of 425 mph.

The conventional wisdom says that this system was developed to an optimal degree with the P-51. The onus is on those who think the bf-109 achieved the same results with what appears to be a markedly different physical design to provide the evidence supporting their opinions.

Not that it matters anyway. Raw performance figures are what matters at the core of this thread, and the angle being sought now seems to center on dismissing P-51 top speed claims as with IL2FB. Nothing new here, actually. This is fine at the end of the day, as long as conclusive, hard data is offered to support those claims. Don't see an awful lot of that here, just tidbits used to support some pretty broad and self serving conclusions.

Charon

[Charon]

double post

[Batz]

The onus is on those who think the bf-109 achieved the same results with what appears to be a markedly different physical design to provide the evidence supporting their opinions.

Who is it that said the 109 achieved the same results?

The only one that comes even close to saying that is HoHun.

Hi everyone,

Having been away for two days I'm unable to catch up with the thread now.

There's one thing I'd like to point out though: After the re-design that occurred with the Friedrich, the Me 109 fully employed the Meredith effect. It's radiator had boundary layer separation with separate discharge, a continously adjustable intake and a continously adjustable outlet that was automatically regulated to create thrust. That's the same degree of sophistication as found on the Mustang.

The thermodynamic effect of the engine cooling was well-known in the 1920s and 1930s and in fact had been first pointed out by Hugo Junkers in 1915 when he acquired a patent for the "Düsenkühler" ('jet radiator').

Is this who you are talking about?

I don't feel like going through and quoting everyone but if you read back from Hohun's post I quoted above I don't think you will read where anyone said the 109 utilized the "Meredith Effect" as "efficient" as the mustang. I don't think anyone said it is all that important in discussing the performance of either the p51 or 109. After all the "Meredith Effect" is already factored in when discussing top speed.

Before Hohun's post the only other talk of "Meredith Effect" was from dtango in answering a couple of questions.

fyi,

I don't think the 109k4 is "needed" in AH. Our g10 performs well enough to sub for it as well as the g6/as and g14/as. What I would like to see is our current g6 have mw50 added and designated as a 109g14. Then I would like to see an early g6 modeled. I like the g6 in AH and when I flew last it was my favorite if not only plane to fly. But there are numerous wholes in the plane set that, at least imo, are more of a priority.

[HoHun]

Hi Charon,

"In this design, the flow expanded gradually as the duct velocity decreased, and the pressure at the radiator face was reasonably uniform. This permitted the appropriate closure of the exit with a temperature-controlled power actuator, and a minimum pressure drop across the radiator consistent with efficient radiator function and cooling demand... "

That's just what the Messerschmitt does, too.

"It seems that most other contemporary airplanes attempting to take advantage of the Meredith Effect failed for one reason or another to combine an efficient duct system with a properly designed and regulated exit-closing mechanism and did not develop the energy recovery inherent in the Meredith method."

"... most other contemporary airplanes ..." is not "all other" - and note the sentence starts rather weak with "It seems ..." anyway.

And again, the Messerschmitt had just the regulated exit-closing mechanism.

>The onus is on those who think the bf-109 achieved the same results with what appears to be a markedly different physical design to provide the evidence supporting their opinions.

Actually, the aspects of the physical design you quoted are shared by the Messerschmitt and the Mustang. I won't claim the Me 109 was superior, but I have no reason to assume it wasn't in the same ballpark at least :-)

Regards,

Henning (HoHun)

[Charon]

If you look at the diagrams for the each radiator, their may be some shared components, but the designs are dramatically different.

In the Mustang:
"A long duct, gradually expanding ahead of the radiator and gradually converging behind it, was essential--the ideal duct, in fact, would have been as long as the entire airplane. While it might be utopian to expect a net thrust, Atwood hoped that what he came to call "the Meredith effect" would offset some or even most of the cooling drag."
http://www.icon.co.za/~pauljnr/radsta.jpg

In the 109:
http://kotisivu.mtv3.fi/thilakari/Kuvat/mtkuvat/Image014.jpg

If I had my scanner working I would post the internal view  of the 109 which shows no excess room around the radiator core, as the photo would suggest. The P-51 also had the boundary layer gutter that separated the cooling air intake from the fuselage - moving the duct away from the fuselage several inches - which is obviously not the case with the 109.
.

Aerodynamicist Irv Ashkenas came up with the idea of moving the entire duct away from the belly skin so that its inlet was in an undisturbed stream of high-speed air. A "gutter" about an inch and a half deep carried the turbulent, low-energy surface boundary layer air clear of the inlet. This arrangement became classic; the F-16's underbelly scoop is reminiscent of the Mustang's. Once the entry design was perfected, the variable-area inlet feature was dispensed with; an adjustable chute at the aft end of the duct controlled the volume of air flowing through it.

Maybe they are in the same ballpark, but maybe they are not even playing the same sport. The conventional wisdom (and Widewings figures) says they are not.

The differences are so glaring, you must just be trolling me to waste my Saturday afternoon with all this mental masturbation involving my learning more about the Meredith effect than I ever wanted to know for a job well done. At least I'll be fascinating at the next cocktail party I attend.

Here's a more involved link on Mustang development controversies over who actually came up with what during the design and on the fit and finish efforts that went into its construction to reduce drag. http://www.airspacemag.com/ASM/Mag/Index/1996/AS/wmtm.html

I'm going to go fly a bit now, while the wife is away.

Charon

BTW: Here a link I came up with that illustrates the fit and finish issues that I noted previously with the earlier G series. It’s not just the MG bulges that jump out at you. The fit and finish on the G improves dramatically aft the engine. I wouldn’t mind seeing similar close-ups of a K series for comparison.
http://kotisivu.mtv3.fi/thilakari/Kuvat/mtkuvat/Image020.jpg
http://kotisivu.mtv3.fi/thilakari/Kuvat/mtkuvat/Image013.jpg
http://kotisivu.mtv3.fi/thilakari/Kuvat/mtkuvat/Image006.jpg

[HoHun]

Hi Charon,

>The conventional wisdom (and Widewings figures) says they are not.

I've seen so much "conventional wisdom" crumble away under careful analysis that I don't value it too highly. Widewing's figures are interesting in stating that the net force generated by the radiator is a drag and not a thrust, which "conventional wisdom" claims the Mustang radiator should generate.

>The differences are so glaring, you must just be trolling me to waste my Saturday afternoon with all this mental masturbation

You post an outside photograph of the Me 109 radiator to compare it to a Mustang radiator cross section, and proceed to talk about "glaring differences"?

The Me 109 radiator had the same components as the Mustang radiator, and if you'd look at the cross section instead of the photogaph, you'd see that it had a very similar internal geometry as well.

>The P-51 also had the boundary layer gutter that separated the cooling air intake from the fuselage - moving the duct away from the fuselage several inches - which is obviously not the case with the 109.

The radiator type introduced with the Friedrich did indeed have a boundary layer gutter though it was not visible from the outside as it was recessed behind the intake flap. The "turbulent, low-energy surface boundary layer air" was guided "clear of the inlet" of the heat exchanger duct just like it was in the Mustang.

Now Gripen tells me that this component was deleted in the Gustav, but it's quite obvious that it didn't make the difference between 2.9% cooling drag (as for the Mustang) and 11.6% (Widewing's Gustav figure) or the Gustav wouldn't have been any faster than the Friedrich (but it was).

For the Mustang, the deletion of the intake flap worked. For the Messerschmitt, it was the deletion of the boundary layer bypass duct. In any case, the sophistication of the Messerschmitt's radiator was equal to that of the Mustang's.

Regards,

Henning (HoHun)

[Charon]

I've seen so much "conventional wisdom" crumble away under careful analysis that I don't value it too highly.

I tend to value it more than idle speculation based on selective data and broad conclusions. It's up to those revising conventional wisdom to provide the concrete data that proves the conventional wisdom incorrect.

You post an outside photograph of the Me 109 radiator to compare it to a Mustang radiator cross section, and proceed to talk about "glaring differences"?

The Me 109 radiator had the same components as the Mustang radiator, and if you'd look at the cross section instead of the photograph, you'd see that it had a very similar internal geometry as well.

My car has all of the basic components of a Porsche 911 -- for some reason it fails to perform the same. As I pointed out in my post, I have a cutaway in front of me in a book. If you have a digital version please post it for a direct comparison. You will see a glaring difference which you also seem to have overlooked from my previous post:

"A long duct, gradually expanding ahead of the radiator and gradually converging behind it, was essential--the ideal duct, in fact, would have been as long as the entire airplane. While it might be utopian to expect a net thrust, Atwood hoped that what he came to call "the Meredith effect" would offset some or even most of the cooling drag."

So, direct question. Does the 109 feature a long duct, gradually expanding ahead of the radiator and gradually converging behind it? Your cross section sure must look a hell of a lot different from mine.

In any case, the sophistication of the Messerschmitt's radiator was equal to that of the Mustang's.

Certainly equalivent to the Spitfire, and many other mid to late 1930s aircraft.

It really is pointless for an agnostic to discuss such things with "keepers of the faith." When you have hard data to back up the specualtion I'd be happy to see it and more than happy to accept it. Until then...

Charon

[GScholz]

Are you an agnostic Charon?

[HoHun]

Hi Charon,

Here's your quote with a different emphasis:

"A long duct, gradually expanding ahead of the radiator and gradually converging behind it, was essential--the ideal duct, in fact, would have been as long as the entire airplane."

Did the Mustang have such a duct? No - and so obviously doesn't match up with the ideal descripton either. About the relative dimensions - well, let's have a look at them.

The approximate geometry of the Mustang's ducts is:

Oil cooler path: 50% intake, 17% radiator, 33% outlet - radiator height 15%
Main radiator path. 40% intake, 20% radiator, 40% outlet - radiator height 20%

The approximate geometry of the Messerschmitt's duct:

20% intake, 30% radiator, 50% outlet - radiator height 27%

That's close enough, especially if you consider that the while the Messerschmitt radiator was deeper, it wasn't just a rectangular box but actually shaped to allow expansion of the intake air within the radiator itself.

>So, direct question. Does the 109 feature a long duct, gradually expanding ahead of the radiator and gradually converging behind it? Your cross section sure must look a hell of a lot different from mine.

The answer is: The Messerschmitt features a slightly shorter inlet duct than the Mustang, gradually expanding ahead of and within the radiator, and gradually converging behind it. I'm sure if you look at the cross section a second time, maybe even armed with a ruler, you'll find the similarity striking.

The much smaller side section of the Messerschmitt's system obviously makes the system appear much smaller than the Mustang's large duct, but this is compensated by the underwing radiators being much wider. Don't let yourself be deceived by the different looks - two ways of skinning the same cat, with minor differences only :-)

(I'll just leave the insulting part of your post unanswered in order to allow you to concentrate on getting the dimensions off your drawing ;-)

Regards,

Henning (HoHun)

[niklas]

So i just studied the duct tests of the P-51, and while moving the radiator farer away of the fuselage definitly placed it in a better position for the air stream, the main effect of reduced drag seems to be a different one.



Here you can download a better scan. Just for the guys like charon who have to base their opinion on funny sketches, book phrases without any proofs,  and photos from the outside lol.

de.geocities.com/stefan_l_01/fzg/DuctEvolution.zip

It can be clearly seen that at minimum flap opening position the massflow of the final duct was 35% lower than for the original duct, the total inlet area being reduced form 197 to 188 inch^2. This alone explains why the later duct produced less drag, it simply had less drag (less massflow) at the expense of less cooling efficiency. This was imo the step from a ground attack aircraft flying in rather warm air (low alt) to the high alt escort Mustang. In high altitude you can close the inlet area, that´s the reason behind the front lip of the 109 radiator btw.

The doc also shows that the later duct had a slighly higher overall "static" cd value.

niklas

[Charon]

Are you an agnostic Charon?

Well, there are plenty of german weapons that were technologically advanced compared to the allied equivalent. Some even represent paradigm shifts. MG34/42; FW-190, Panther, Type XXI U-boat, V-2 (couldn't have got to the moon without the Germans) etc. I have no problem with that. The allies had the A-bomb/B-29, enigma breaking/purple breaking etc., centimetric radar etc. I certainly have no prolem with that. Frankly, if you substitute the FW-190 for the P-51 in this discussion I would be approaching the subject from the same basic position The 109 was a great plane but like plenty in the LW stated, it was a bit long in the tooth by 1944.

I'm personally a huge P-38 fan, and have been since I first read Martin Cadin's Forked Tail Devil 30 years ago at age nine. However, I accept that the 38 was a mixed bag. A great plane, but one that both excelled and lacked. I also came to see Cadin in a different light  as a historian than I did at 9 years old - largely through the valid criticism of others. But then, the same applies for Galland and "The First and the Last."

Charon

[Charon]

That's close enough, especially if you consider that the while the Messerschmitt radiator was deeper, it wasn't just a rectangular box but actually shaped to allow expansion of the intake air within the radiator itself.

Then you should be able to find data showing similar efficiency. The only data provided so far (by Widewing) seems to to indicate that the 109 radiator was far less efficient.

You know, you're not debating me. You're debating Edgar Schmued and Lee Atwood. You're debating decades of that distrusted conventional wisdom. It's up to the person looking to do the revision to back up the theory with proof. Don't be insulted if I tell you I find Schmued or Atwood to be far more credible on the subject, and at least as objective. They seem to think North American came up with something pretty unique in its execution.

So i just studied the duct tests of the P-51, and while moving the radiator farer away of the fuselage definitly placed it in a better position for the air stream, the main effect of reduced drag seems to be a different one...

If you and Henning take your casual studies and assumptions and get them published by at least a minimally credible source -- or show data from someone who did -- your positions will have greater weight. Can you show source material from the Messerschmitt factory or company engineers establishing equal efficiency? That's fine too. Are you an aeronautical engineer formally trained in this area? If so, get that paper published and establish source material -- it would probably cause a minor stir.
 
I'm not a big fan of speculative "fact." I deal with it all the time as part of my job today, and I helped craft it in a former life.  I've dealt with companies that claim you can slap a conventional magnet on a pipe and get essentially "soft" behaving water from hard water -- the magnetism aligning the calcium particles in a certain way... They back it up by taking bits and pieces of various scientifc theory that selectively overlooks other areas, flow dynamics for example, that would negate the theoretical possibilities. They even hired a hack at Univ. Fla. to support the scientific basis of their technology with a "study" that could never pass peer review. But the average customer wouldn't know the difference (it sounded all technical and such) and it sold a lot of magnets.

The trade group I worked for at the time actually conducted several legit, peer-reviewed, published studies that could find no benefit from magnetic water softening. However, there was always some minor factor the magnet people claimed wasn't followed (it wasnt turned quite the right way, etc.) that "negated" the legit research when contacted by the press or state attorney generals offices, etc. I just don't see much difference here.

Charon

[HoHun]

Hi Charon,

>You know, you're not debating me. You're debating Edgar Schmued and Lee Atwood.

I'm debating Atwood alone, and I'm not alone in debating him. Other North American engineers don't even connect Atwood (or Meredith, who was Atwood's "discovery") with the radiator problem at all.

From the Air & Space article you referenced:

"Atwood's article brought a rebuttal from aerodynamicist Ed Horkey, who had come to North American from the California Institute of Technology in 1938 to work under Schmued. The aft location, he said, was an obvious choice; there was no room for a suitable radiator anywhere else. Neither he nor Irv Ashkenas, another Caltech-trained aerodynamicist who worked on the Mustang, remembers Lee Atwood having had a role in that decision."

>They seem to think North American came up with something pretty unique in its execution.

Then what was unique? :-) The Allison Mustang and the Friedrich had almost exactly the same subcomponents, arranged to almost the same geometrical proportions. (Do you remember you talked about "glaring differences"? Where are they?)

It's obvious that North American and Messerschmitt followed the same design intention. Do you concede that?

It's equally obvious that North American and Messerschmitt used the same subcomponents in their design. The solutions for the boundary layer problem differed. Do you concede that?

A cursory study of the geometry shows us that there is no marked difference in the proportions of the cooling systems of the Mustang and the Messerschmitt. Do you concede that?

>However, there was always some minor factor the magnet people claimed wasn't followed (it wasnt turned quite the right way, etc.) that "negated" the legit research when contacted by the press or state attorney generals offices, etc. I just don't see much difference here and have a higher standard for fact.

Well, if you'd posted that before the "smaller noodle" bit, or before the "keepers of the faith" bit, or before the "mental masturbation" bit , I might actually have been impressed :-)

Regards,

Henning (HoHun)