Explain this and win the prize!

[gripen]

Dweeb,
Hm... When I started this thread, only thing I knew was that generalized formulas seem to give quite high value of the e. Since then I have studied quite  a lot drag data and so far I can conclude that these generalized formulas really give too high value of the e.

What I have calculated above is based on tested data, in wind tunnel and also in the flight (models as well as real planes). I have no idea how Wood or NADC created their formulas but probably not using data from the WWII fighters.

I have not claimed e factor constant, Perkins&Hage makes this quite clear and this can be seen partially from the wind tunnel data as well as flight tested data. However, in many cases there is a linear stage as pointed out in the Perkins&Hage.

I have not claimed  that the e factor is same for all WWII fighter planes, again data shows that there is variation but not particularly due to the aspect ratio.

The problem here is that you join in the discussion with the attitude that all my doings are wrong and you continously try to put things to my mouth which I have never claimed. And for one reason or another you refuse to prove you claims; you are not discussing here and this is a discussion forum. Apparently you want to stop all discussion about the e factor; I don't know why, your posting history might give somekind of clue.

The data I have used is above, if you know better data, please bring in or point out my errors. Otherwise I continue my search and will ad results to this thread as something new comes in.

gripen

[Crumpp]

And for one reason or another you refuse to prove you claims; you are not discussing here and this is a discussion forum.

I would say he has proved the point on the Wooden Models Gripen.  

I would definately say, just as Perkins&Hage states, that Aspect Ratio is a major factor in induced drag formation.  I believe the word is "instrumental".

I don't think your qualified to start changing estabilished theories just yet.

Crumpp

[gripen]

Originally posted by Crumpp
I would say he has proved the point on the Wooden Models Gripen.  

Well, all I see above is that Wood wrote something 1935 and corrections have improved since. And there should be corrections regardless model size.

Originally posted by Crumpp
I would definately say, just as Perkins&Hage states, that Aspect Ratio is a major factor in induced drag formation.  I believe the word is "instrumental".  

Wow, you have finaly found out that the aspect ratio is a major factor in the induced drag formation:

Cdi = (Cl^2) / (pi * AR * e)

But I think everyone else here allready knew that.

gripen

[Crumpp]

But I think everyone else here allready knew that.

Obviously YOU did not.  Your whole argument has been that it is not a factor in determining the efficiency factor.  Perkins&Hage say it is along with Wood and the NACA.

Well, all I see above is that Wood wrote something 1935 and corrections have improved since. And there should be corrections regardless model size.

What color is the sky in your world?  Can you read?

Crumpp

[gripen]

Originally posted by Crumpp
Obviously YOU did not.  Your whole argument has been that it is not a factor in determining the efficiency factor.  Perkins&Hage say it is along with Wood and the NACA.

Actually I say above that in the case of the tapered wings there seems to be correlation like theory suppose but it is not particularly strong.

But that is not true in every case. If we have no idea about the form of the wing, there is no way to determine e factor from the aspect ratio only.

gripen

[Dweeb]

Originally posted by gripen
Dweeb,
Hm... When I started this thread, only thing I knew was that generalized formulas seem to give quite high value of the e. Since then I have studied quite  a lot drag data and so far I can conclude that these generalized formulas really give too high value of the e.

Nope, when you started this thread, you had no idea that the value of the Airplane Efficiency Factor e was affected by Aspect Ratio, infact you wanted others to explain it to you, you even offered a pathetic prize, here is what you actually said:

Originally posted by gripen
In the "Draining E in turns" thread rose a question if the Oswald's efficiency factor (know also as e factor) can be estimated from the unknown wing by knowing only the aspect ratio of that wing. In other words, is it possible to estimate the lift distribution of the wing by knowing only the aspect ratio of it?

So I open a little contest: The first one who can explain if this is possible or not with sensible logic will receive a pdf copy of the RAE report called: "Notes on the Dog Fight" from me. As a bonus prize the winner will also get a flight tested German report on the Bf 109G/AS for performance analysis.

gripen

Then, after you were given sources to refer to, namely: Airplane Performance Stability and Control, by Perkins & Hage you picked up a copy and began posting selective extracts from it pretending you knew the answer the whole time.

Originally posted by gripen
I have not claimed e factor constant, Perkins&Hage makes this quite clear and this can be seen partially from the wind tunnel data as well as flight tested data.

No true Gripen, you actually posted a table of calculations and stated that a constant value of  e = 0.8 was better than the formulas posted by the experts… You said:
   

Originally posted by gripen
It can be seen that generalized formulas result about twice larger average error than the constant value…  so it is possible to create a better working general formula than Wood's or NADC.

Gripen, I think I prefer to believe that you are simply going around in circles without realising it because you have such a weak grasp of the subject and that you are trying desperately to comprehend Perkins & Hage fast enough to stay up with this thread, because that only implies you are foolish, the other alternative is that you are simply lying to save face… Your choice?

Originally posted by gripen
I have not claimed  that the e factor is same for all WWII fighter planes, again data shows that there is variation but not particularly due to the aspect ratio.

Yes you have, you said that a constant value of 0.8 was better than the equations posted by the experts, and you even backed it up by saying:

Originally posted by gripen
Why the efficiency factor should not be similar among the planes with very similar dimensions?

Which of course is complete baloney, as already explained in previous posts!

Originally posted by gripen
The problem here is that you join in the discussion with the attitude that all my doings are wrong and you continously try to put things to my mouth which I have never claimed.

Nope the real problem is that you have been making absurd claims, and then denying it and lying about it, as your nonsense is shown for what it is.

Originally posted by gripen
And for one reason or another you refuse to prove you claims;

Gripen, you are the only person making claims here, the onus of proof rests entirely with you. You haven’t proven anything here yourself, despite your pompous claims! None of your endless diatribe constitutes proof, it lacks the transparency and rigour of proper academic exposition and actually qualifies as little more than the ranting of a spoilt child trying to gain influence in a gamers board.

Dweeb.

[gripen]

Originally posted by Dweeb
Blaah Blaah Blaah

Basicly you are doing here same thing as Crumpp. You post arguments after arguments without proof and you purposedly understand wrong my sayings.

If you want to challenge my calculations, you should post something relevant.

BTW Dweeb's posting history is interesting, quite little posting since 2001. Here is a typical example how he pops in and the attitude seem to be allways quite similar as here. Makes me wonder if he has another user name here.

gripen

[Dweeb]

Originally posted by gripen
But that is not true in every case. If we have no idea about the form of the wing, there is no way to determine e factor from the aspect ratio only.

gripen

Gripen, don’t you understand anything you read? Take another look at the equations you have been posting, the aspect ratio is a fundamental part of those equations, you can’t determine e without it, and nobody ever said you could determine e with aspect ratio alone.

Your original post was regarding corrections to e for aspect ratio, and you have already seen in Perkins & Hage that there are corrections for aspect ratio. Glauert has shown that two corrections for aspect ratio influence the drag and the lift curve slope, which has an influence on the efficiency factor first demonstrated by Oswald, and is absolutely based upon the lift and drag coefficients and the aspect ratio… In Perkins & Hage there are graphs of the correction factors as functions of aspect ratio alone, that have been pointed out to you by others. That is enough proof for anyone. You simply couldn’t be more wrong, and you just don’t seem able to see it.

Dweeb

[Dweeb]

Originally posted by gripen
Basicly you are doing here same thing as Crumpp. You post arguments after arguments without proof and you purposedly understand wrong my sayings.

Gripen,

You are the one who makes post after post, all complete nonsense, and you not only refuse to respond to my rational arguments regarding your data, you have not provided any proof for anything you have said, because most of it is contrary to accepted aerodynamic theory. 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

[gripen]

Originally posted by Dweeb
You are the one who makes post after...blaah blaah

I'm actually only one who has calculated something here and I have given the sources and so far you have proven nothing wrong on these.

I won't aswer to your arguments because you purposedly understand my sayings wrong and you behave very agressively. For one reason or another you seem keep discussion about determining the e factor as some kind of threat.

The funny thing in your posting history is that it's the most agressive I've seen in this board. I quess the reason for this is that you have another alias for normal use and Dweeb pops up only when you want to be extreme agressive.

gripen

[Crumpp]

I'm actually only one who has calculated something here and I have given the sources and so far you have proven nothing wrong on these.

That is a FLAT OUT LIE.

What do you call this?  You know I calculated the "e" factor using every formula you could come up with.  Since you did not like the answers you began making up your own theories!!  In fact you asked me NOT to be so detailed in my calculations.  You couldn't follow it.

Lets see and compare total drag @ 440fps at the Spitfires FTH altitude with the correct data:

BF 274 - 795.641828 @ 440 fps
Total Drag FW-190A5 -718.2845242@ 440 fps

BS354 - No data listed except the A/C was 7 mph slower w/50 bhp more output than the Merlin 66 @ (+18)

BS543 - 810.863789
FW-190A5 - 705.7484202

BS551 - 758.4823884
FW-190A5 - 704.890256

EN524 with 4 bladed prop - 765.4635575
FW-190A5 - 702.4712376

BS310 with 4-bladed prop - 793.0539968
FW-190A5 - 751.8834689

BS310 with 5 bladed prop - 794.0663191
FW-190A5 - 749.7161496

JL165 - done to death

MA 648 Merlin 66 (+18) SU Pump - 838.0549776
FW-190A5 - 804.8037275


BS310 - 792.6552588 Parasitic drag - 691.672177

FW-190A8 - 794.3964059 Parasitic drag - 606.4158622

At 315mph the total drag situation changes completely in the FW-190A8 favor.

JL165 vs FW-190A8 has been done to death, again in the FW-190A8's favor.

MA 648 is the ONLY Spitfire Mk IX to beat the FW-190A8 for drag and here is why:


quote:
--------------------------------------------------------------------------------
External equipment of the above four aircraft was similar with the exception that MA.648 had the new pattern of air intake.
--------------------------------------------------------------------------------

MA648 - 837.1701001 parasitic drag - 751.6212076
FW-190A8 - 869.2121249 parasitic drag - 709.9624067

The parasitic drag is always in the FW-190's favor but the total drag drops to within a few pounds of each other at 315 Mph but never swings in the FW-190's favor.

So ONE example of the Spitfire Mk IX with an experimental air intake beats the FW-190A8 in total drag. The others are behind their FW-190A contemporary the whole way.

That about covers the Spitfire Mk IX's vs. their contemporary FW-190 adversary.

Now this works out the same NO MATTER WHOSE formula you use for "e" factor. At least all the normal accepted ones. It probably won't once Gripen finishes his "theory".

Crumpp

[Angus]

So, as a result the Spitfire Mk VIII beats the 190 in total drag then?
Do you know if any of those were clipped?

Oh, edited with the purpose of addition.
You asked about Mach and drag. That is a special category. I have some bit of text about it and can post if you like.
What beats me is that you don't seem to have known of it.

[Dweeb]

Originally posted by gripen
I'm actually only one who has calculated something here and I have given the sources and so far you have proven nothing wrong on these.

Yes but your calculations are all based on specious data, which is why your results are complete nonsense. If you want anyone to take your wind tunnel data seriously, you need to post a lot more information about it, for example, the method of supporting the model and the control of associated turbulent flow problems, and the degree of detail in the model, for example were details such as the radiator details, intakes, pitot heads, radio masts, airspeed and air temperature booms, antenna, guns or gun ports, gun and ammunition door and hatches included on the model? Were any other measures taken to simulate discontinuities in those locations? What corrections were made for Mach number and dynamic pressure calibration? What corrections were made for Reynold’s number? Was the  static pressure survey in the tunnel conducted with multiple booms and how were local air disturbances handled? What corrections were made to the Mach number and aerodynamic coefficients for the blockage factor due to the model? What corrections were made to the angle of attack and drag coefficients due to the presence of the tunnel walls? Those are the sort of details you need to be discussing, along with some very self critical estimates of the size of the error bars involved… The burden of proof rests with the person making the claim, and we are still waiting.

Originally posted by gripen
The funny thing in your posting history is that it's the most agressive I've seen in this board. I quess the reason for this is that you have another alias for normal use and Dweeb pops up only when you want to be extreme agressive.
gripen

I assume you mean aggressive… LOL! I can’t believe I’m arguing with someone who can’t even spell his accusations correctly!  Gripen, why don’t you stop pouting and wipe your teary eyes and try to provide some of the proof you have been asked for, instead of just repeating the same old nonsense over and over again, and finally resorting in desperation, to conspiracy theories?

Originally posted by gripen
I won't aswer to your arguments because you purposedly understand my sayings wrong and you behave very agressively. For one reason or another you seem keep discussion about determining the e factor as some kind of threat.

Gripen, your spelling is almost as bad as your aerodynamics. Three incorrect words in a single sentence, I wonder if you have even finished high school?  

However, the real reason you won’t answer my arguments is because you can’t! I have challenged you to provide the proper transparency and rigour required to transform your arguments from the nonsense they are. The burden of proof always and without exception, rests with the person making the claim. It is therefore your responsibility to demonstrate that your data and the resulting calculations are valid, which is impossible to do because “Performance estimates based on model test results are unsatisfactory because of the large and uncertain corrections necessary to make the results correspond to the free flight of a full sized airplane.”

The only things you have proven successfully in this thread, is that your data and thus the resulting calculations are meaningless, that you haven’t owned your copy of Perkins & Hage for long enough to understand it properly yet, and that your general level of education is somewhere between the 7th and 8th grade... Congratulations!

Dweeb

[Angus]

Dweeb, don't be a dweeb and start picking on gripen about spelling details if you have nothing moreworthy to promote.
BTW, it is most common for non-english Europeans to spell some words as "address" and "aggressive" with a single d or g, since these are international terms, such as in Swedish, German and such.
Now, if you're an American, just imagine the Brits go picking on you. LOL, Torpedo, Tomato, etc...
Now, you can fight about wind tunnels as you like. There is however a reason for the application of wind tunnels, bear that in mind. After all, they are the ultimate simulation before a flight test, - highly adjustable, and modifications are quick in for a test.
The end-effect is what matters. If you know the thrust and the weight, the rest is up to the aerodynamics, and real life this time!
So, if a Spifire is faster than a 190 with the same thrust at a given alt there must be less total drag, - and vice versa.
But in a wind tunnel there may be even less error in the thrust department, note that !
We have data showing most in the 190's favour maybe (?). However some Spits seem to claw themselves  in front.
So why?

[Dweeb]

Originally posted by Angus
Dweeb, don't be a dweeb and start picking on gripen about spelling details if you have nothing moreworthy to promote. BTW, it is most common for non-english Europeans to spell some words as "address" and "aggressive" with a single d or g, since these are international terms, such as in Swedish, German and such. Now, if you're an American, just imagine the Brits go picking on you. LOL, Torpedo, Tomato, etc...

Point taken.

Originally posted by Angus
Now, you can fight about wind tunnels as you like. There is however a reason for the application of wind tunnels, bear that in mind. After all, they are the ultimate simulation before a flight test, - highly adjustable, and modifications are quick in for a test.

Any designer will tell you there is only one reason they use models in wind tunnels… cost! Airplane design by building, testing, changing and retesting models is essentially a confession of ignorance of the designer, it is an attempt to make design by trial and error, less expensive than the millions involved in working with full size aircraft. No designer would ever dream of claiming that their model test results are likely to be close in terms of performance, that’s not what they are intended for. They save a lot of money, and a lot of big mistakes in terms of balance, dynamic stability, and integration, in the very early stages of the design process.  More and more money has been spent refining the techniques and corrections to the point where the wind tunnel testing of models has become an essential part of aircraft design that can save billions on modern projects. In the 1940s model testing was in its infancy, and designers couldn’t use those tests for performance prediction with any hope of worthwhile results and they still don’t.  That’s why development programs include the full range of tests, from scale models initially, to full size model testing, to prototype tests all before the aircraft ever gets near a runway, and eventually every new aircraft is subject to a huge range of flight tests, and even then, performance estimates will be changing as the tests evolve. I don’t normally like to be so blunt, but using model tests the way Gripen has, is just plain silly, and he wouldn’t believe it even if Kurt Tank told him in person ;-)

Originally posted by Angus
But in a wind tunnel there may be even less error in the thrust department, note that !
We have data showing most in the 190's favour maybe (?). However some Spits seem to claw themselves  in front.
So why?

Sorry Angus, I don’t understand what you are asking? Scale model tests are never conducted with engines installed, so thrust isn’t a factor.

Dweeb