Explain this and win the prize!

[Crumpp]

Exactly,

He keeps chasing his tail.  Does not want to admit his data is faulty on the Spitfire.

Even when a man who teaches this stuff for a living sets him straight!

Crumpp

[gripen]

The NACA report on the wind tunnel tests with a 1/2,75 scale model of the F4U-1 can be found from here. The drag polar results e factor value 0,77.

We have now eight values of e factor for tapered winged WWII fighters with varying value of aspect ratio; not a large set but we can easily determine formula for e factor with these and compare results to the generalized formulas:

e = 0,9815 * AR ^(-0,1341)

In the table below the new formula is marked as e-f:



As we can see the new formula gives much more accurate results, the error being one eight or less than with the generalized formulas. The next step would be adding taper ratio as well as washout to the formula but even in this form it works pretty well.

gripen

[Dweeb]

Originally posted by gripen


As we can see the new formula gives much more accurate results, the error being one eight or less than with the generalized formulas.
gripen

Ok, that seems to be about it for this thread, so let’s see where it has lead us.


1) 1933 Oswald publishes his original paper and it is available for download from the NACA report server. Glauert was then first to derive a theoretical expression for rectangular wings, in the form of a correction to the value for elliptical wings that could be applied to Oswald’s work.

2) 1935 Professor Wood published his empirical methods, which are based on flight test data.

3) 1949 Perkins & Hage publish Oswald’s methods along with other eminent aerodynamicists of the time, including Dwinnel & Jones. Infact, every aerodynamics text book since includes and supports that work.

4) Dr Raymer publishes another empirical method based on NADC data from 1966 in his book on aircraft design in 1999.

5) Lednicer produces similar results using computational aerodynamics and publishes his results in an article in 1999.

6) Then in 2004, Gripen claims they are all wrong and that his method is better. He publishes a new concept, the e value for every plane is practically the same and entirely refutes thousands or hours of research and negates the work of some truly great men…

Gripen… you have not a shred of credibility, give it up already. LOL!!

Dweeb

[gripen]

Originally posted by Dweeb

1) 1933 Oswald publishes his original paper and it is available for download from the NACA report server. Glauert was then first to derive a theoretical expression for rectangular wings, in the form of a correction to the value for elliptical wings that could be applied to Oswald’s work.

Hm... Actually it was von Prandtl (1918) who introduced whole theory of the lift distribution. Some time later (1926) Glauert published his formulas for the rectangular wings, it should be noted that his formulas as well as Glauert's are for the wing only. Oswald published his work 1933 and he introduced the term of the e factor for the entire airframe.

Originally posted by Dweeb
2) 1935 Professor Wood published his empirical methods, which are based on flight test data.

I don't know what kind of data Wood used for his empirical analysis. But we can be sure that there is no any WWII fighters.

Originally posted by Dweeb
3) 1949 Perkins & Hage publish Oswald’s methods along with other eminent aerodynamicists of the time, including Dwinnel & Jones. Infact, every aerodynamics text book since includes and supports that work.

Yep, and these are the methods I have used for my analysis.

Originally posted by Dweeb
4) Dr Raymer publishes another empirical method based on NADC data from 1966 in his book on aircraft design in 1999.

Again, I don't know what kind of data set is used for the NADC dataset but it's probably based on something else than WWII fighters.

Originally posted by Dweeb
5) Lednicer produces similar results using computational aerodynamics and publishes his results in an article in 1999.

Lednicer calculated lift distribution for three planes and did not claim any specific value for the e factor.

Originally posted by Dweeb
6) Then in 2004, Gripen claims they are all wrong and that his method is better. He publishes a new concept, the e value for every plane is practically the same and entirely refutes thousands or hours of research and negates the work of some truly great men…

Thank you for great logic, seems that you best even Crumpp in that area.

What I really say above is that generalized formulas by Wood and NADC seem to give too high e factor for the WWII fighters and this is backed up by empirical data. The most probable reason for this is that these formulas are probably based on something else than WWII fighters. Most WWII fighters had very similar dimensions and therefore also the values of the e factor are very similar.

gripen

[Dweeb]

Originally posted by gripen
Hm... Actually it was von Prandtl (1918) who introduced whole theory of the lift distribution. Some time later (1926) Glauert published his formulas for the rectangular wings, it should be noted that his formulas as well as Glauert's are for the wing only. Oswald published his work 1933 and he introduced the term of the e factor for the entire airframe.
gripen

Wrong, Oswald was first, that's why they named it after him! LOL!

Gripen, I'm sorry but this has to be said... Those experts and their data are all correct... You are just a confused amateur with a deplorable attitude and no credibility.

The data you have, has been available to aerodynamics experts for decades, and during analysis of WWII fighters throughout the 40's they all applied it, because they all acknowledge Oswald's theory.

Even today modern universities use those methods, and still teach it, it appears in almost every text book on the subject.

If you have discovered that they are all wrong, and that the e value for all WWII fighters was really the same, point us to your learned papers or journal publication... LOL!

You started this thread confused, and then declined from there! It is time for you to stop wasting everyone's time with your nonsense... let it go!

Dweeb

[gripen]

Originally posted by Dweeb
Wrong, Oswald was first, that's why they named it after him! LOL!

Why don't you just read what Oswald really wrote; he directly refers von Prandtl's theory.

Glauert published his works actually 1926/1929 and these are used as sources in many NACA documents as well as other publications.

What Oswald did was just continuation of the work by von Prandtl, Glauert and others, while Prandtl and Glauert handled lift distribution along the wing as relative factor, Oswald expressed theory to the drag of the entire airframe. Besides Oswald's report is actually about performance calculations and the efficiency factor is just one small but important part of it.

Originally posted by Dweeb
Gripen, I'm sorry but this has to be said... Those experts and their data are all correct... You are just a confused amateur with a deplorable attitude and no credibility.

Of the mentioned persons only Perkins&Hage and Lednicer actually have studied WWII fighters and what I have calculated above is strictly based on their works. And the typical e factors claimed by Perkins&Hage are 0,7-0,85 (p. 95).

Originally posted by Dweeb
If you have discovered that they are all wrong, and that the e value for all WWII fighters was really the same, point us to your learned papers or journal publication... LOL!

Could you please point out from where you have got the idea that I have claimed that mentioned persons are all wrong?

All I say above is that generalized formulas by Wood and NADC seem to give too high value of the e factor for WWII fighters and this conclusion is backed up by empirical data. The most probable reason for this is that these formulas are created for different kind of airplanes; say relative large winged and slow planes combined with small fuselage. According to your logic this means that I claim all written about lift distribution and e factor wrong.

Generally if you want to discuss, please use logical and verifyable arguments.

gripen

[Dweeb]

Originally posted by gripen


Generally if you want to discuss, please use logical and verifyable arguments.

gripen

That’s very funny, coming from a guy who is quoting from a book that he doesn’t understand (or you wouldn’t have opened this thread with such a dumb question), can’t even spell the word verifiable, and uses third party wind tunnel data to produce completely erroneous results. Even better, after starting this thread without a clue, you already claim to have revolutionized the theory. Don't you think it is time you faced the fact that you don't have the knowledge, the experience, or the credentials to be carrying out any kind of aerodynamics research, let alone refuting the very solid work of renowned experts, that has been accepted for decades... You are not just a bumbling amateur, you are a fool who unsuccessfully tries to sound as though you know something by flooding threads with so much relentless nonsense, that everyone else gives up.

If you want anyone to believe your silly claims, do some original research, have your academic work published and then point us to the publication... The simple fact is, even a first year aero major would laugh at your nonsense, so why don't you just give it up and stop wasting everyone’s time with your complete and utter baloney.  

Dweeb

PS  Happy Thanksgiving!

[gripen]

Dweeb,
I have claimed all my sources which include wind tunnel data from various sources as well as flight tested data. I have given the guidelines for the calculations as well as the results. If my errors are so easy to see and laughable, why don't you just point them out.

gripen

[Dweeb]

Originally posted by gripen
Dweeb,
I have claimed all my sources which include wind tunnel data from various sources as well as flight tested data. I have given the guidelines for the calculations as well as the results. If my errors are so easy to see and laughable, why don't you just point them out.

gripen

Gripen,

I don't need to, because you don’t have an ounce of credibility. You claim to have found that Oswald’s efficiency factor is practically constant for a wide range of fighter aircraft built during the war years. If it were true it would mean that people like Oswald, Professor Wood and every other professional in the field has been mistaken all this time, and that Oswald, Professor Wood and Dr Raymer have wasted their time, wasted fortunes in research, and years of effort only to produce results that while being accepted in aerodynamics for decades, you have easily refuted it with some third party data. You claim the number was a constant after all, but not only that, you further claim to have found out what it is… As I said, if you want to be taken seriously with such laughable nonsense, do the same thing as those before you, do your research, present your paper for peer review and then publish! You will then either become famous or expose yourself as a fool. I know which one my money is on… LOL!

Dweeb

[gripen]

Originally posted by Dweeb
I don't need to, because you don’t have an ounce of credibility.

Sounds that  you are not discussing here, just blaming me for something without proof.

Originally posted by Dweeb
You claim to have found that Oswald’s efficiency factor is practically constant for a wide range of fighter aircraft built during the war years.

Why the efficiency factor should not be similar among the planes with very similar dimensions?

Besides the data for the  Bf 109G, Fw products, F4U and F2A is above. Please point out my errors.

gripen

[gripen]

In another thread rose a question about the drag of the P-80, NACA data from the flight tests and wind tunnel test with a 1/3 model can be found from here.

The e factor of the P-80 seems to be about 0,75 at Cl range 0,2- 0,8. Which again fits very well to the other data seen in this thread.

Regarding accuracy of the wind tunnel data, this report gives also interesting read:

"The agreement of the flight and wind-tunnel data is excellent at all Mach numbers of the test"

Dweeb is again most wellcome to show my errors.

gripen

[Crumpp]

"The agreement of the flight and wind-tunnel data is excellent at all Mach numbers of the test"

Again you need an english lesson Gripen.

The report says in the very NEXT sentence that the results in the low speed realm where "fortuitous" .

http://dictionary.reference.com/search?q=fortuitous&r=67

Happening by accident or chance. See Synonyms at accidental.

Crumpp

[Angus]

Sweet Jeezus.
You are incurable hagglers.
Now please be nice

[gripen]

Originally posted by Crumpp
The report says in the very NEXT sentence that the results in the low speed realm where "fortuitous" .

What it exactly says is:

"The close agreement between the low-speed data may be partly fortuitous considering that flight-test was computed from the thrust (the predominate force at low speed) taken from an engine calibration chart."

This thread is about e factor and lift distribution not semantics.

gripen

[Dweeb]

Originally posted by gripen
Besides the data for the  Bf 109G, Fw products, F4U and F2A is above. Please point out my errors.

Why? So you can get a free education?

The simple fact is, you have already asked some pretty dumb questions, like the one you opened the thread with, and had some excellent answers by some very knowledgeable people, who according to you are all wrong. Despite the help you have received already, you still claim that the books that explain the theory, even the guy who has had it named after him, and Professor Wood, and Dr Raymer are all wrong, because you claim to have found that the airplane efficiency factor, is not a factor after all, it is a constant!  Can’t you see how absurd that is? Do you really think that after decades of work, and countless years of research, it was all wasted because you are the first person to figure it out?   Yeah right!

Dweeb