Spitfire XIV vs Bf-109 K-4 vs La-7 vs Yak-3

[drgondog]

I'm in no way trying to gloat, that is again prick like behavior.

However I do often talk in absolutes, it's not the first time I've been accused of that and I know it.

But infact believe it or not all I want is for me and Bill to agree on this. And I was hoping that after Bill showed the good will by posting in my "Help me out finding a new rimfire rifle" thread, I thought we were starting to get some progress.

We were - on my initiative until your above series of posts.

You have work to do to take Gene's comments and one by one stick them against each of your 'Fw 190 wing comments' that I just requoted for your benefit, to prove your points.. a LOT of work

Then take Gene's comments against my Post 77 and do the same thing to disprove what I said.

 

[Soren]

Ahem!

Crumpp Lednicer agree that the the Fw-190 achieved elliptical lift distribution in turns, just like I tried to explain to you, and both explaining how!

Uh, no they don't say that.. and the Fw 190 and the Spitfire and the Mustang all start with somewhat of an elliptical lift distribution BEFORE the turn and have an 'elliptical like' (more for Spit/less for Fw 190 and Mustang) lift distribution in the turn.

Nothing about G forces 'achieve' elliptical lift in turns, they (G forces) only tend to shift lift distribution based on aeroelastic effects.

 

[Soren]

Bill I posted the entire mail in its original form, and all I wrote is there in the exact original context!

So stop believing I'm trying fool anyone here man! Go contact Gene for crying out loud!

 

[Kruska]

My vote goes to the Spit. If the contending pilots of the Spit and '109 are both exceptionally skilled, it seems rather problematic. OTOH, if we're talking about AVERAGE pilots of 'equal ability', then the friendlier handling of the Spit would give it the edge.

In the words of Captain Eric Brown, RN...

"The Bf 109 was, indeed, a prolific, necessary and timely fighter but was not as great as the Spitfire, the Mustang or the Hellcat, which all had many fewer vices for wartime pilots to overcome."

JL

I gave the same reasons for placing the Spit above the 109

Regards
Kruska

 

[Soren]

Then take Gene's comments against my Post 77 and do the same thing to disprove what I said.

The problem is Bill, that you change your mind between different posts (Read the qoutes in my last post #142), which is what got us into this mess.

 

[Kruska]

I like the 'Momma' analogy a lot. Momma said some comforting things to Soren, but he was confused regarding who was saying what, and maybe is still confused regarding how to put Momma's very good advice to help support him against that mean bully that didn't always say nice things to him.

I bow in sincere respect to your intelligence and abillity of interpretation in between the lines.

Regards
Kruska

 

[Soren]

Again the second mail in its entirety:

I see, so I was wrong when I said that Fw-190's wing achieved basically fully elliptical lift distribution in turns ?

No you are right. That is what causes the harsh stall. It is not a design feature however. It is just and explanation for the two different stall characteristics of the design.

It was my understanding that the Spitfire's wing didn't achieve fully elliptical lift distribution because of the washout applied to the wing all the way out to the tips.

You are right on this too. The Spitfire does not achieve the full efficiency benefits of elliptical wing construction due to the washout. At the same time though it is probably the most efficient of the three. If we examine the aircraft at a design optimum point, you will find little to no difference.

This is what I've been saying all along, which I think everyone following this thread can testify.

 

[Soren]

Oh btw, Gene notes that the full elliptical lift distribution occuring in turns wasn't a design feature from the start, which I said it was, so on that point I was wrong and I gladly admit it.

 

[drgondog]

Soren - I missed your email to Gene and now I see it. Apologise for thinking you didn't show it.

Here is what one of your comments to me prior to your email to Gene

The Fw-190's wing was twisted 2 degree's but left straight at the ends so that under G's the twist was removed, thus creating elliptical lift distribution over the wing. And as we both seem to know ellipitical lift distribution is sought after because it offers the best 'e' value (Which is used to acquire the Cdi).

But - Here is what you said to Gene in the email

The Fw-190's wing achieved elliptical lift distribution during G's because of aeroelasticity negating the original 2 degree twist applied to the 190's wing. This is what caused the violent departure in turns when pulling G's as compared to when stalling at 1 G.


In other words - you 'fudged' by adding the aeroelasticity comment after I pointed it out to you

This is what I said

"So, Lednicer (and I say) aeroelastic bending caused the outboard shift in lift distribution, combined with no twist in outer region of wing, which in turn resulted in the outboard chunk of the wing reaching critical stall at the same time..


and further

Bill - We just finished settling the fact that the Fw 190 cut out the outer 20% span's twist - they sacrificed tip control for aerodynamic efficiency in a straight line

Soren -The wing was left straight at the ends to gain the benefits of elliptical lift production at the tips making the tips more efficient and reducing induced drag production.

Bill - "This is true - and the reason it lost tip control at nearly the same time it lost the rest of the wing lift.. So? It was a design feature in cruise and an design flaw in high speed/high angle of attack manuevers.

When aeroelasticity removes this twist then the FW-190 exhibits a harsh stall.

Actually I am not exactly sure that the issue was torsion (remove the twist) Soren, in fact I suspect bending because of the outboard shift to lift distribution - as I indicated several pages ago - but you wouldn't know the difference. Inboard (and aft) shift of Lift distribution from the wing stress axis usually results from Torsion as the CP tends to move aft. Outboard from bending" - (same effect either way - the CLmax at the tip is reached at the same time as the inboard (twisted)region)

This is what Gene says

This statement refers to the fact aeroelasticity removes the aerodynamic twist placing the airfoil sections at the same co-efficient of lift. The sections then reach CLmax all at the same time. When one side of our wing or the tips stall, the aircraft will drop a wing or if the stall is large enough, the aircraft will roll inverted. That is what Lednicer is saying. This was not a design feature. It is just an explanation for the differences in the FW190's stall behaviors.


Next - I will find some areas where you quoted me out of context in your email to Gene if you wish to pursue this further?.

 

[Soren]

Bill there's no point in dismantling the email, what was said was said to the specific question comment made, it's all in the original context.

I only quoted you once and Gene got to see the whole thread as-well, so he got the whole argument in its original context.

Now come on Bill, just admit you were wrong this time.

 

[Hunter368]

Nah - I have enormous respect for Crumpp, and as I noted I AGREE with the comments contained. The reason I keep drawing Soren back to my Post 77 is I sate several of the same things - then go on to explain how aeroelasticity affects load distribution over a wing - to tie into the Lednicer speculation.

I like the 'Momma' analogy a lot. Momma said some comforting things to Soren, but he was confused regarding who was saying what, and maybe is still confused regarding how to put Momma's very good advice to help support him against that mean bully that didn't always say nice things to him.

Soren - I am ready to discuss why I said Aeroelasticty was more an art than a science in WWII. But first I want You to start by describing the analytical problems to be solved to get an accurate model of an airframe as a system.

Absent your understanding of That - you will be like a goose in a barnyard when I get into the what's and the Why's??

Your ball.

As I just noted I was more interested in what Soren said to Gene?

The Momma (made by kruska) comment that was made was not needed, all it did/does is create more bad blood between you and Soren when you responded to it. It was not witty or called for. Surely you see it for what it was, mud slinging.

I understand you will say Soren does his fair share of mud slinging also, but will no one take the high road between you?

Then responded to the email in a great way, with facts and questions. But the damage was done already.

 

[Soren]

I fear this will never be resovled as Bill seems unable to admit when he is wrong..

Oh and thanks for saying I basically don't know the difference between left right Bill, that was definitely the way to go!

 

[Kurfürst]

... I wonder if the last couple of pages containing the Soren vs. Bill stuff could be moved to the Soren vs Bill thread..?

 

[Hunter368]

... I wonder if the last couple of pages containing the Soren vs. Bill stuff could be moved to the Soren vs Bill thread..?

It was closed.

 

[Kruska]

Hello Hunter 368,

I guess you didn't get the message, Soren unfortunately didn't get it either. My Momma post just pointed out that bringing in a third party doesn't solve the problem since it is about Soren and drgondog who present opposing interpretations of their posts which are not relevant to their individual accounts towards a third party who isn't even involved in the dispute regarding of interpretations of posted opinions by the other two parties.

So a confused Soren is now trying to back up his dispute with other participating posts.

Am I wrong? Well then I would have no problem to apologize to Soren, but what interpretation of my Momma post on your behalf makes you legible to call me a mud slinger?

Regards
Kruska

 

[Soren]

I am not confused at all Kruska (Why would you even say that ??), and bringing in an experts opinion is definitely not straying off topic.

Sometimes you unfortunately need two mouths to get the message across.

 

[Marcel]

It was closed.

Nope, the other one is still open

 

[drgondog]

Again the second mail in its entirety:




This is what I've been saying all along, which I think everyone following this thread can testify.

Now, for a little context - bring forward all the 'quotes'

Soren sez
And what do I know ? Well I know that aerolasticity was a very well known science before WW2, that the effects of aerolasticity is taken advantage of by a/c designers to improve a/c performance in certain flight envelopes, that the Spitfire didn't have an elliptical lift distribution, that the Bf-109 Spitfire both turned allot better than the P-51, that the Fw-190 featured elliptical lift ditribution in turns. And most importantly I can prove it, Bill can't.


Before I go further, can Soren now state that the designers of Fw 190 wing fully understand aeroelasticty effect on the wing tip in High G turns - or were they just 'having fun' with those hotshot pilots and 'give em' a suprise in a Gunfight?

My Reply to that particular jewel earlier

Bill sez -Next - the Spitfire, with an eliptical wing, does not have a pure elliptical lift distribution, but a lot closer than the 51 and the Fw 190A and D.. I pointed out examples of the spanwise lift distribution presented in one of Lednicer's plots.

Next - to even the least knowledgable but enthusiastic studiers of the art of wing design, the twist at the tip for the wing chord is to ensure that the tip region (simply for you, the aileron area) of the wing stalls last, with stall starting inboard and moving out board. To those pilots on this forum that means when we screw up and lose ability to fly say, on final approach, we want to sink - not roll.

You are free to be you, Soren, and think it is all about giving the Fw 190 'elliptical lift' distribution in high G turns. You are equally free to 'prove your thesis' and now that you have said you can, please do not complain when I follow you around on this commitment

Very specifically - we do NOT design tip twist to develop 'elliptical' lift distribution as you posed for the Fw 190 a week or so ago. And last on this subject the twist is to SPECIFICALLY alter the chord angle of attack Downward so that the relative angle of attack in the outer wing doesn't stall when the inboard region reaches the stalling angle of attack.


T quote from Gene's email to you

I do know Bill. He is not only very knowledgeable but someone I consider a friend. It is very disappointing to hear that you two cannot get along discussing old airplanes.

I can certainly clarify what I meant however the two points do not seem to be related or at least I cannot see how they are related. The only thing in common is the term "elliptical lift distribution". Lednicer is referring to the cl/CL ratio which gives us a clue as to the wing efficiency. The analysis is made at 360Kts at 15,000 feet and is good for that condition. Wing efficiency will change with condition of flight and square wingtips can very easily be designed that equal elliptical wings. However they are designed to be that optimal for a specific condition of flight. For example at the Prmin point, L/Dmax, or Va would serve as a design point depending on what the performance the designer desired.

Since the Mustang and FW190 are designed to most efficient at one design point and the Spitfire has an elliptical wing which is efficient at all points, Lednicer's observation is correct in that the Spitfire probably has the most optimal of the three. Probably is used because the aerodynamic twist in the Spitfire wings in order to prevent the wing from stalling all at once reduces this efficiency. That too would be designed for an optimal point of performance.


Soren sez -The Fw-190's wing was twisted 2 degree's but left straight at the ends so that under G's the twist was removed, thus creating elliptical lift distribution over the wing. And as we both seem to know ellipitical lift distribution is sought after because it offers the best 'e' value (Which is used to acquire the Cdi).

From Gene -This statement refers to the fact aeroelasticity removes the aerodynamic twist placing the airfoil sections at the same co-efficient of lift. The sections then reach CLmax all at the same time. When one side of our wing or the tips stall, the aircraft will drop a wing or if the stall is large enough, the aircraft will roll inverted. That is what Lednicer is saying. This was not a design feature. It is just an explanation for the differences in the FW190's stall behaviors.

To Summarize from my Post 77

Let's take these one at a time

From pages 550-551 - chapter Elements of Finite wing theory, "Principles of Ideal-Fluid Aerodynamics", Krishnamurty Karamcheti, Professor of Aeronautics and Astronautics- Stanford Univesity.. Published by John Wiley and Sons -1966

"To obtain an elliptic lift distribution on a (geometrically and aerodynamically) untwisted wing, the spanwise distribution of the chord should be elliptic"

Point 1. Elliptical Wing is the optimal planform for minimum Induced Drag
Point 2. Varying the tip ratio to approximately .4 will closely approach an Elliptical Wing as far as reducing the induced drag at the sacrifice of adding more weght (for same aspect ratio)
Point 3. The downwash corresponding to an elliptic lift distribution is a constant all along the span, further the rolling and yawing moments on such a wing are zero no matter how the chord, the angle of attack and the wing section are arranged.

Further, from 12:8-9 Spanwise Lift Distribution under Load "Supersonic and Subsonic Airplane Design" by Gerald Corning Professor Aeronautical Engineering Department - University of Maryland 1960

Point 4. The downwash corresponding to a trapezoidal wing planform varies along the span
Point 5. The spanwise lift coefficient for a trapezoidal wing planform changes with the downwash along the span.
Point 6. The G forces have bearing only on the elastic properties of the wing - and have nothing to do with lift distribution Unless and Until the wing twists or bends to change the relative angle of attack from 'no load' angle.
Point 7. The changes which tend to throw lift load Outboard are a function of bending rigidity, while the changes which tend to throw lift load Inboard are a function of torsional rigidity.

Therefore - pulling high G's seemed to affect the Fw 190 for two reasons (not known when designed) a.) aeroelastic bending of the Fw190 wing, moving the lift distribution outboard, and b.) not having twist in the outboard 20% of the span. As Lednicer quotes the LW report dated January 1944 you may presume he knows more about the German explanation than you do.


Make your own judgements..

 

[Kruska]

Hello Soren,

Maybe confused is the wrong word, maybe wringing for help-support describes it better. But anyway, please just disregard my post for the sake of a friendly continuation between our posts and opinions, okay

Regards
Kruska

 

[Hunter368]

Hello Hunter 368,

I guess you didn't get the message, Soren unfortunately didn't get it either. My Momma post just pointed out that bringing in a third party doesn't solve the problem since it is about Soren and drgondog who present opposing interpretations of their posts which are not relevant to their individual accounts towards a third party who isn't even involved in the dispute regarding of interpretations of posted opinions by the other two parties.

So a confused Soren is now trying to back up his dispute with other participating posts.

Am I wrong? Well then I would have no problem to apologize to Soren, but what interpretation of my Momma post on your behalf makes you legible to call me a mud slinger?

Regards
Kruska

Sorry you seem you also slightly misunderstood my post as much as I did yours.

1) Soren purposed using Crumpp who is very knowledgeable on the subject (more so then even Bill or Soren), Bill never opposed the idea at the time. Then you posted your Momma comment, which "perhaps" I (and Soren) slightly misunderstood. When Bill then made his comment about his Momma (which is what I called mud slinging by him not you), I thought he was now discrediting Crumpps opinion b/c it did not agree with his opinion. Which Bill clearly up also shortly after, agreeing with Crumpp.

As often happens with Soren and Bill, they talk past each other. Not sure if by accident or intentional.

In summary I was commenting about Bill not you. The only thing I said about your post was I thought it was not needed and just the problem worse between them. I did reread my comment and i see how you read into my comment what you thought. I worded it poorly, I meant to slip in Bill's name not yours. Sorry