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Throttle and propeller RPM!


NORTHMAN

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  • ED Team
Yes, that's the report I had in mind, thank you for linking it. Notice that the P-51B gun ports are rather close in their design - obviously the primary consideration was maintenance.

 

The outer MGs on the Spitfire were kind of an afterthought, weren't they, after the requirement for +4 additional MGs arose, they had to enlarge the wing to its well known form, and fit those extra MGs in it whereever possible. Hence their seemingly random arrangement.

 

See the attached picture from the report you linked, for the P-51B installation. On page 17 of this report there is a table, noting DeltaCLmax = -0.05 for the "fabric torn" condition (and -0.12 for the completely unsealed gunport).

 

The curve marked with "+" ("tape torn" rather than completely "unsealed") appear to be most relevant for the change in Drag Coefficient and Lift Coefficient.

 

To me it appears that the drag increase is proportional to Angle of Attack change (i.e. both negative and positive Cl change increase drag with the 'torn' and 'unsealed' installations)

 

Analoges for the cannon installation are also available in the report for Drag increase with Cl increase.

 

My question to the developers is the following: is this Cd / Cl effect from the tape being torn on the gun ports is being simulated in DCS - i.e. for the P-51D and upcoming Spitfire IX LF? Does the FM differentiate between sealed and 'fired' gun ports?

 

The effect is circa 0.0005. The minimal CD is about 0.02 at speed flight, so it is about 2.5% that gives about 1% in terms of maximum speed, for example...

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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The outer MGs on the Spitfire were kind of an afterthought, weren't they, after the requirement for +4 additional MGs arose, they had to enlarge the wing to its well known form, and fit those extra MGs in it whereever possible. Hence their seemingly random arrangement.

The weird arrangement of the spit's wing MGs is a consequence of the thinness of the wing- spacing them out like that was the only way to accommodate 8 guns and an acceptable ammunition load in the wing, the ammo boxes being long and narrow to fit within the structure. AFAIK they always planned on having the elliptical shape. The plane where the wing became elliptical (or semi-elliptical) to accommodate weapons was the Tempest: making the wing semi-elliptical allowed them to fully enclose the cannons in the wing (once the shorter Mk V cannons were fitted) for a marked reduction in drag, and probably also helped accommodate the ammo given that the wing was much thinner than that of the Typhoon. I guess the long, projecting cannon barrels on most Hispano armed fighters had a pretty noticeable effect on performance, otherwise they wouldn't have bothered.

 

The 109 had the same problem as the spit when it came to fitting guns in the wings- they never managed to fit anything more than single 8mm MG in the 109 wing without some kind of bulge or gondola to provide room for ammo (though certain late model 109s have so many lumps and bulges you might not notice a few more).

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I would risk saying it would make more difference to the overall fidelity of the FMs than, say, a request to a tiny change the 3D model of the elevator on the Spitfire, on grounds that though its existed in the period, it was not typical enough to satisfy a real gourmet of combat aviation. Or that the shape of cannon barrel is not very typical for a certain batch of Spitfire over Normandy.

 

I'd call these small, tiny, minuscule details about which personally I cannot care less, but its apparently a matter of paramount importance for some guys. Oh well, now we have a different slightly different shaped balance on the Spit, huzzah.

 

In contrast, a change of 0,05 to 0.12 in Cl is not entirely small or insignificant. At least that's what I gather from some long raging blood feuds fought with religious zeal over a difference of 0.18.:megalol:

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

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The effect is circa 0.0005. The minimal CD is about 0.02 at speed flight, so it is about 2.5% that gives about 1% in terms of maximum speed, for example...

 

Thanks for the answer YoYo, but is this a yes or no? Is the effect modeled or not?

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

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  • ED Team
Thanks for the answer YoYo, but is this a yes or no? Is the effect modeled or not?

 

No, and never will be. But, regarding the Spitfire stall, there is a very different song...

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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Ok, so if I gather right, the Drag Coefficient changes are not /not planned to be implemented, but to the second part of question (DeltaCLmax change from gun port condition) is/will be implemented, hence the comment effecting stall characteristics..?

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

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I would risk saying it would make more difference to the overall fidelity of the FMs than, say, a request to a tiny change the 3D model of the elevator on the Spitfire, on grounds that though its existed in the period, it was not typical enough to satisfy a real gourmet of combat aviation. Or that the shape of cannon barrel is not very typical for a certain batch of Spitfire over Normandy.

 

I'd call these small, tiny, minuscule details about which personally I cannot care less, but its apparently a matter of paramount importance for some guys. Oh well, now we have a different slightly different shaped balance on the Spit, huzzah.

 

In contrast, a change of 0,05 to 0.12 in Cl is not entirely small or insignificant. At least that's what I gather from some long raging blood feuds fought with religious zeal over a difference of 0.18.:megalol:

 

Which just shows your ignorance over the elevator issue.

 

"...our aerodynamicists at Hursley Park thought that an even more effective answer could be obtained by enlarging the horn balance of the standard elevator and this we did by stages. The effect was astonishing. At last a way had been found to improve the basic static stability margins of the aeroplane..." from Spitfire by Jeffrey Quill, p237, ISBN0-09-937020-4


Edited by DD_Fenrir
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Oh, the 'issue' that you have repeatadly claimed not to exist because there were no stability issues in the first place...? Curious, how selective one can be with his books isn't it.

 

Anyway, I am so glad that resources are being spent on a detail like this while other, final release modules basically miss their whole weapons loadout...

http://www.kurfurst.org - The Messerschmitt Bf 109 Performance Resource Site

 

Vezérünk a bátorság, Kísérőnk a szerencse!

-Motto of the RHAF 101st 'Puma' Home Air Defense Fighter Regiment

The Answer to the Ultimate Question of the K-4, the Universe, and Everything: Powerloading 550 HP / ton, 1593 having been made up to 31th March 1945, 314 K-4s were being operated in frontline service on 31 January 1945.

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Anyway, I am so glad that resources are being spent on a detail like this while other, final release modules basically miss their whole weapons loadout...

 

it was easy enough, simply provided the facts and evidence that it should be so and the devs acted accordingly to correct the issue.

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  • ED Team
Which just shows your ignorance over the elevator issue.

 

"...our aerodynamicists at Hursley Park thought that an even more effective answer could be obtained by enlarging the horn balance of the standard elevator and this we did by stages. The effect was astonishing. At last a way had been found to improve the basic static stability margins of the aeroplane..." from Spitfire by Jeffrey Quill, p237, ISBN0-09-937020-4

 

As we can not model stick-free stability, it plays no role. :)

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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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The effect is circa 0.0005. The minimal CD is about 0.02 at speed flight, so it is about 2.5% that gives about 1% in terms of maximum speed, for example...
Ahem :music_whistling:. Thanks Yo-yo, you always spot on :thumbup:.

 

 

Anyway, I am so glad that resources are being spent on a detail like this while other, final release modules basically miss their whole weapons loadout...
it was easy enough, simply provided the facts and evidence that it should be so and the devs acted accordingly to correct the issue.
And I would add, as has been repeatedly proven in these forums when the right information is provided. It's not like me, nor I think anyone here, want any module in DCS to be less realistic to the point that current data can provide, but you have to provide the data, not this or that guy said those and I like more how it sounds than what we have.

 

 

Mate, really, I knew for all my sim life, and I have said in the past, that the day we had the opportunity to have an ultra realistic 109 model to the last consequence the 109 fanboys wouldn't be happy at all. I knew,and so we can see it right now, because you all don't look for realism, you look for a dream of 109 that doesn't exist at all, so you have to find something for the Spit you fear even though we didn't even tried yet? C'mon… :huh: Talking of what, is this still a Spitfire thread?

 

 

S!

"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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Oh, the 'issue' that you have repeatadly claimed not to exist because there were no stability issues in the first place...? Curious, how selective one can be with his books isn't it.

 

Anyway, I am so glad that resources are being spent on a detail like this while other, final release modules basically miss their whole weapons loadout...

 

You mean *repeatedly*.

 

I've said nothing of the sort. The definitions 'unstable' and 'neutrally stable' though very different for most of us seem to mean one and the same thing to those with an axe to grind. I have acknowledged the limited range of movement for CoG inherent in the Spitfire (with quotes) and whose repercussions affected a single mark in particular - not the Mk.IX incidentally - the effects of which were mitigated by bob-weights and adherence to correct load out instructions.

 

All this I have covered with relevant quotes before in the relevant threads. If you choose to ignore them because it does not fit your argument then that is not my issue. It does however become an issue when you choose to mis-represent my opinions. I'll ask you not to do that again.


Edited by DD_Fenrir
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As we can not model stick-free stability, it plays no role. :)

 

Understood. However, if I understand correctly, given that both the bob-weight or the modified elevator essentially allowed for a little more tolerance in CoG movement regards stability, is this modelled?

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  • ED Team
Understood. However, if I understand correctly, given that both the bob-weight or the modified elevator essentially allowed for a little more tolerance in CoG movement regards stability, is this modelled?

 

Again, the terms you operate are the terms of STICK-FREE stability. By the way, these measures were not absolute. I have copies of a lot of pages of the documents where it is discussed.

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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