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Dora stall speed


Crumpp

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  • ED Team

So, the tailless model without trim losses is good for you? Not for me...

 

No, I only argued with a statement that "any conventional airfoil is better than laminar". You have not seen the main feature of P-51 airfoil: it is more sensitive to high Re and responds with max CL increasing, so at high altitudes and low M it can be worse than conventional airfoil.

 

But if you can see there is no evidence of 1.58 in this report for 230XX.

 

So, I have to unveil one thing: the reports like 824 review providing airfoils section (2D) charachteristics are usually serve for aeroengineers as a guide - what airfoil is to be choosen for the certain aircraft.

The wing based on these 2D charts is calculated using one of numerical methods for the ISOLATED WING with own twist - geometrical and/or aerodynamical and tapered, so the results may vary from 2D. Usually, a model is built, more complicated with orifices like in TN 1299, and the report is done for one model - detailed.

Then. usually, the later and more detailed reports are more accurate, so referring to 1299 (May 1945) the upper limit for an isolated wing without fuselage, without trim loss IS LESS than 1.58 in any case.

Will you argue that a real plane can have the same value?

Ok, then the latest (Nov 1945) report (NACA-WR-L-51, NACA-ACR-L5G10), Re and M are close to the full-scale flight conditions, very detailed investigation for only one model...

Spanwise load distribution, lift carpet... and the maximum is barely 1.45...

 

So, I guess this thread will be ended as its parental thread...

What is for 1.35...1.38 for the whole plane: a lot of correlating values from the reports, concerning the tapered wings with twist, that are very close to FW 190 wing.

 

By the way, report 829 you mentioned and eventually failed to point the plane with similar 230xx wing having 1.6 at clean wing.

 

TN-1044 having F6F with 230xx but does not have any evidence of "1.58" but having 23015 reference showing the tendency not to rise with lowering M.

 

Lavochkin plane WT test for a fullscale plane (the same wing although a bit different planeform).

 

May be I missed something but I think it's enough.

 

What are your arguments:

very unclear 1.58 value from FW doc

2D WT tests (as far as I can see, 824 report uses existing results for 230 series obtaine much earlier than 1945)

 

 

I do not hope that I can ruin your faith... it's just for other people that can decide themselves.

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Yo-Yo no'one ever argued that 'any' conventional airfoil was better than any laminar (at least not intentionally), there are simply way too many types of conventional & laminar flow airfoils to make such a sweeping statement. Also there's clearly one area where the laminar flow airfoil introduced an improvement, and that was at high speed, making it ideal for jets.

 

All that was ever claimed was that the 23xxx series features a higher CLmax than the laminar 66 series at real world Re numbers and at the dogfighting speeds of WW2 type aircraft, and all the relevant flight & windtunnel tests confirm this.

 

Now as for the 1.58 CLmax figure, we've been arguing over wether this was for a clean aircraft or one with flaps & gear down, but obviously it's for a clean aircraft as a) CLmax with flaps & gear down is substantially higher and b) US WT figures are identical showing 1.55-1.60. Question then becomes wether it is for a WT model or a real aircraft with trim losses, and here evidence seems to suggest it's for a model. However the exact same applies to the P-51 where there are loads of perfect smooth model WT tests showing great laminar flow characteristics & high 1.4 CL numbers etc., only problem is it didn't show up in actual flight tests and much less so on service aircraft.

 

In short we need to compare apples with apples here, and thus use only figures that are presented in direct comparison, not cherry pick figures we "like". Only then can we get the most accurate result.

 

Finally, contrary to your belief I don't have any faith or emotional attachment toward any of these aircraft, but I do have an amibition of helping the devs of my favorite simulators get things as accurate as possible. That's why you see me doing tests with all the modules I buy, be they from ED, Heatblur, Razbam, Belsimtek or Magnitude. I do this to confirm wether they match up with the available information, and mostly they do, but when they don't I have to speak up because otherwise it simply kills the immersion for me.

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  • ED Team

 

Now as for the 1.58 CLmax figure, we've been arguing over wether this was for a clean aircraft or one with flaps & gear down, but obviously it's for a clean aircraft as a) CLmax with flaps & gear down is substantially higher and b) US WT figures are identical showing 1.55-1.60. Question then becomes wether it is for a WT model or a real aircraft with trim losses, and here evidence seems to suggest it's for a model. However the exact same applies to the P-51 where there are loads of perfect smooth model WT tests showing great laminar flow characteristics & high 1.4 CL numbers etc., only problem is it didn't show up in actual flight tests and much less so on service aircraft.

 

In short we need to compare apples with apples here, and thus use only figures that are presented in direct comparison, not cherry pick figures we "like". Only then can we get the most accurate result.

 

.

 

Having no valued arguments you are trying to state false arguments. 1044 does have FLIGHT TEST RESULTS FOR P-51, not WT. And anyone can see it.

Trying to prove something wrong in DCS you are achieving the opposite target, especially as you mention "the SIM that does better work on props". The story of fw190 CLmax 1.58-->1.15-->1.35 (!) was almost forgotten until you woke it up. Stop, please... By the way, you have got a bad fork: to confess that the "better SIM" is wrong with 1.35 like DCS or you are wrong with 1.58.


Edited by Yo-Yo
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Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Yo-Yo I feel a lot is being missed in translation here because it honestly feels like you've not read my posts at all....

 

1) I agree that there are actual P-51 flight test data in TN 1044, and I am saying you need to compare that side by side with the flight test data of the F6F (because it features the same airfoil selection as the Fw190) in the same report

 

2) If you want to use WT numbers then the 1.58 figure applies for a clean aircraft with the NACA 23015-23009 selection.

 

To be more specific I am not saying a Clmax of 1.35 is wrong, what I am saying is that anything higher or similar for the P-51 is wrong, and that based on all the data available.

 

However if you want to use solely WT figures to simulate a perfectly smooth and ideal airfoil, as seems to be the case for the laminar flow airfoil, then you need to do the same for the conventional types, and then 1.58 applies for NACA 23xxx.


Edited by Hummingbird
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  • ED Team
Yo-Yo I feel a lot is being missed in translation here because it honestly feels like you've not read my posts at all....

 

1) I agree that there are actual P-51 flight test data in TN 1044, and I am saying you need to compare that side by side with the flight test data of the F6F (because it features the same airfoil selection as the Fw190) in the same report

 

2) If you want to use WT numbers then the 1.58 figure applies for a clean aircraft with the NACA 23015-23009 selection.

 

To be more specific I am not saying a Clmax of 1.35 is wrong, what I am saying is that anything higher or similar for the P-51 is wrong, and that based on all the data available.

 

However if you want to use solely WT figures to simulate a perfectly smooth and ideal airfoil, as seems to be the case for the laminar flow airfoil, then you need to do the same for the conventional types, and then 1.58 applies for NACA 23xxx.

 

You really never read my posts... and every time you distort the point. There was no discussion about new or worn wing... it was a long story why 2D section data can not be applied to the real aircraft. So, I quit...

Ніщо так сильно не ранить мозок, як уламки скла від розбитих рожевих окулярів

There is nothing so hurtful for the brain as splinters of broken rose-coloured spectacles.

Ничто так сильно не ранит мозг, как осколки стекла от разбитых розовых очков (С) Me

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Let it be… He probably realised he was mistaken and tried to get a honourable exit. Can't blame him.

 

 

Nevertheless, great FM talking :thumbup:.

 

 

S!

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"I went into the British Army believing that if you want peace you must prepare for war. I believe now that if you prepare for war, you get war."

-- Major-General Frederick B. Maurice

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You really never read my posts... and every time you distort the point. There was no discussion about new or worn wing... it was a long story why 2D section data can not be applied to the real aircraft. So, I quit...

 

New or worn wing? No, the 1.58 figure was a WT figure for a clean aircraft, no flaps, which was the first argument (You argued it was with flaps), I provide NACA report 824 to show it clearly wasn't. Then you move on to explain why you didn't use such WT figures due to them leaving out trim loss and the difference between perfectly smooth WT models & the real aircraft etc. - which is a fair point and one I completely accept (!). But the very same precaution needs be applied to all aircraft/airfoil selections then. The point is to be consistent, and not cherry pick and mix WT & flight test figures.

 

Next you bring up NACA report TN 1044 as the source for your laminar flow & conventional type airfoil characteristics at varying Mach numbers, yet at the same time you choose to ignore the relevant tables and use completely irrelevant aircraft with symmetrical airfoil selections as substitutes for the F6F/FW190 and compare them with the P-51. As a result you end up with figures that simply don't correlate with the actual differences recorded during flight testing under similar conditions, see Fig 4, 14 & 12.

 

Thus how you can feel that I distort anything is beyond me, but so be it, I've tried my best to explain the discrepancies that are present and where you might have made a small error. I don't want to argue just for arguments sake, I am only pointing out all of this in the hopes of correcting any possible mistakes and crucially achieve transparency about the sources for the FM.


Edited by Hummingbird
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  • ED Team
I am only pointing out all of this in the hopes of correcting any possible mistakes and crucially achieve transparency about the sources for the FM.

 

And you pointed it out many times, and you have been answered many times (even if its an answer you don't like or understand), so now it's done. Yo-Yo/ED doesn't think there is an issue. End of story.

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