P-38 Bugged

Discussion in 'Engineering Retrospective' started by -ALW-, Jan 25, 2003.

  1. -ALW-

    -ALW- Well-Known Member

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    Wing Loading And Turn Performance..IDIAMN 1 JG27 AFRIKA posted 12-16-98... ...Wells posted 12-16-98 10:58 PM ET (US)

    Wing loading is only a guide (wing area is only one factor in the lift equation). A shorter wingspan has nothing to do with it as in that quote! The airfoil chosen has a LOT to do with it as well. For example: The P-38 uses an airfoil that is capable of pretty high lift coefficient without stalling. This is partly due to the thickness of the wing and the camber (curvature) of the airfoil.

    Induced drag is directly connected to aspect ratio (ratio of span to average chord), so a high aspect ratio makes for lower induced drag and higher turning speed (more G's).

    A plane that has a higher top speed will also have a small advantage, due to it's ability to overcome drag with thrust. Anything that will maintain a higher turning speed will allow for more G's to be pulled.

    Good turning performance favours a wing that is ample in area, has a low aspect ratio and a low maximum lift coefficient (induced drag is also figured from the lift coefficient squared). This is exactly where the Spitfire is at. It has a thin wing (low Clmax), low wing loading (ample area) and reasonable aspect ratio. The 109 uses slats (higher CLmax and a slightly higher aspect ratio to give it's turn performance while also allowing for higher speeds). The modified clark-y airfoil has one of the best lift/drag ratio's as well, which helps climb performance.

    Also, look at the stalling speeds for the planes. A lower stalling speed will allow a plane to pull more G's for any given speed.

    Planes with good flaps that increase wing area (P-38, Ki-84) can benefit from a notch for better turn performance.

    Read this for anyone interested in it.
     
  2. Kutya

    Kutya Banned

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    I'd never use steroids.
     
  3. -ALW-

    -ALW- Well-Known Member

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    I'd never use drugs or smoke at all....gives you dain bramage.
     
  4. -ALW-

    -ALW- Well-Known Member

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  5. -ALW-

    -ALW- Well-Known Member

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    And what does the note on this chart say? (underlined in red)
    Forgot to add that info in a reponse before.
     

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  6. Kutya

    Kutya Banned

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    Me neither.
     
  7. -ALW-

    -ALW- Well-Known Member

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    RGREAT, I know there is a lot of supporting info here but I would like a response. Tell me what you think?
     
  8. rgreat

    rgreat FH Developer

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    I see you question mine or badger sources, but do not provide you own ones that can speak in fawor of P38 updating.

    Lots of links, but they all show only 'standart' limited data (name/length/weight/'top speed' type ones). And even more, i see there no data that can be used as your arguments.
    If i missed one, please quote the numbers that you think can help.

    P.S. I repeat lets not count 'momories' as a reliable source of information. As you see they can completely differ from each other.
     
    Last edited: Mar 8, 2003
  9. zxszxs

    zxszxs Banned

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    чем не цифра?

    ------------------

    P.S. Отрадно очевидное стремление привести WB к реалу.

    Однако для этого рано или поздно придется учитывать и такие, более неочевидные, чем power/weight и weight/wing area, показатели, как:

    (posted by -exec- (-учус- :D) )

    code:--------------------------------------------------------------------------------
    Размах Площадь Удлинение
    LA-5FN 9.80 17.50 5.49
    YAK-9 9.74 17.15 5.53
    P-47D 12.42 27.87 5.53
    Spit-9 11.23 22.48 5.61
    P-51D 11.28 21.69 5.87
    MIG-3 10.20 17.44 5.97
    BF.109G 9.90 16.20 6.05
    Typhoon 12.67 25.92 6.19
    FW.190A 10.50 17.70 6.23
    BF.110F 16.20 38.40 6.83
    P-38J 15.85 30.43 8.26
    --------------------------------------------------------------------------------


    как ни крути, а придется стать авиаконструктором, хотя бы на четверть.
     
    Last edited: Mar 9, 2003
  10. -ALW-

    -ALW- Well-Known Member

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    Hey ZXSZXS....could you translate that text to english? I don't speak Russian :dunno:
     
  11. -ALW-

    -ALW- Well-Known Member

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    What I will ask is: What information do you use to model the aircraft? You must use some kind of data I would expect. One thing I noticed are many who fly other planes such as the 109 or 190. They seem to know what is wrong with the planes and they are improved once there is enough noise and complaining. How is it that they may have enough info, and what kind of info do they present? The info I would guess prefers those aircraft. All I can tell, is that someone says something like..."this thing rolls horrible/crappy" or, "this thing is too slow, too sluggish etc" and you changed the settings for some reason. I've been going on and on about the P-38 being undermodelled at this point, but I should have started long ago. I do wish the plane settings were like the older one(pre 1.5;1.51), with the exception of flap usage.
     
    Last edited: Mar 9, 2003
  12. -ALW-

    -ALW- Well-Known Member

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    Oh really? Better re-read the post.

    What is wrong with 'standard' data? Truth hurt? I can deal with true facts. Can we not use that data since it is universal and available for most any aircraft? Same again...re-read the post if you missed something.

    This sounds like hypocrisy.
    Oh really, I'm glad you pointed out my corrections.
    I'm just merely repeating what is written. But this IS getting off subject.
     
  13. rgreat

    rgreat FH Developer

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    Я не в курсе как конкретно их учитывать :)
    Как сильно удлиннение влияет на маневренность?
    Влияет на что конкретно?
    Отодвигает срыв потока? Повышает подьемную силу?
    Есть специалисты?
     
    Last edited: Mar 9, 2003
  14. rgreat

    rgreat FH Developer

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    ALW....well...im really tired now.
    And i have absolutely no interest to continue read your attacks anymore.
    I already have more then enough stress in real life.

    Sorry. Discussion with you ends here.
     
    Last edited: Mar 9, 2003
  15. rgreat

    rgreat FH Developer

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    У нас около 75-80. Это неплохой показатель. К примеру у 190а4 - около 100.
    И интересно откуда этот пилот взял цифру...
    Я не не настолько доверяю развлекательной литературе, особенно с таким однобоким взглядом на самолет.

    К примеру взгляни на спецификации 'P-38L' на той страничке.
    Указана скорость для P-38L, а вес при этом для P-38F...

    Прямо таки как и название этой книжки - "A Dream Comes True".
     
    Last edited: Mar 9, 2003
  16. -ALW-

    -ALW- Well-Known Member

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    Attack? :duel: Who said I was attacking? :dunno: You sure don't understand me do you? :confused:
    I comment to a post, simple. If you don't understand, then I wonder why you even post these remarks. If real life stress is too much, then what are you doing here? :dura: I don't really care. :zzz:

    And if I could have an english post to read, I would be able to figure out what is being written. I see a lack of courtesy when I see russian and no english counterparts. Are you trying to ignore me now? :shuffle:

    I've asked this question so many times and you NEVER answer, but rather dance around it... "What info do you use to model the aircraft in WarBirds?" If I get an answer to that question, well....I guess I'll have to provide some info for those said answers right? ...Fill in the blanks. How difficult could this be?:dunno: :rolleyes:
     
  17. -exec-

    -exec- FH Consultant

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    учис :)
    [/B][/QUOTE]

    plane, wingspan, surface, lengthening (L²/S)
    ____________

    P-38 minimal speed handling was taken from FW.190A-3Dg comparative tests at Dansford, Jun'42.
    ____________

    "Standard data" is not the issue to change "non-standard" characteristics.
    ____________

    FH-Staff is not info-bureau, Alw.

    You problem is that your long posts are very hard to extract concrete suggestions.

    Bug-fix request must be short as lightning, relating to only one-two technical characteristics, but must refer reliable sources.

    If you want several things to be fixed, you must enumerate them in several bug-fix requests, accordingly.
    ____________

    And from myself, personally. I don't love to read rainbow textes.
     
    Last edited: Mar 12, 2003
  18. -ALW-

    -ALW- Well-Known Member

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    Sorry, this makes no sense at all to me. Could you put the data with this? And what does "lengthening" represent?
    Well, this is interesting. Do you guys throw out standard data and use your own guesswork (God forbid) to model the aircraft? :dunno: :confused:

    NOOOOW......... this is a question that could use an answer per that comment....(-exec- quote as I understand it: "Standard Data" is not used to model WBFH aircraft), so we rather use ??? :dunno: ???? data for modeling.
    "Info bureau"? If I understand what you are saying, are suggesting that the FH staff go on a whim to model these aircraft? I would sure hope they have stats or some kind of chart showing current settings for all aircraft. I do think that the settings should be accurate, whether it hurts or helps. I hope this is not modeling fairness, because that would make "realistic" and "accurate" bogus"

    Yes, forgive me oh short winded ones, I am but a long winded fellow.

    Lightning strikes may be short in duration, but they are not so in length ;)
    Where did rgreat get his "reliable sources" for these planes on WB? Some of these planes don't have that kind of data existant.
    I may just stop in at Lockheed Martin here in Fort Worth, Tx (about 20min away) and ask them for data. I don't think the data they have will be disputable; after all, they do have a connection with the P-38 don't they ;)

    Ok, but it's difficult to elaborate on one particular issue when they are all connected and affect the one issue. If I needed to seperate each issue I guess rgreat didnt' mention that.
    ____________

    So what? I live in a colorful world. I'm not colorblind :cool:

    (-alw--: <---Feels like he is pulling teeth to get answers and info :dura: )
     
  19. -exec-

    -exec- FH Consultant

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    damn... calm down, calm down, exec...

    ALW, go to Lockheed and ask if they can provide data on:

    *sustained turn times for P-38G, P-38F, P-38J-10, P-38J-25, P-38L.
    *climb charts of planes named
    *roll charts of planes named
    *commentaries/recommendations about low speed handling, and roll, turn, pitch, yaw characteristics at low speeds
    *aircraft flight manual, operation guide, pilot's notes, whatever it's called.
    *values of landing speed, minimal speed.
     
    Last edited: Mar 11, 2003
  20. terror

    terror Well-Known Member

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    Я не думаю, что это прямо сильно поможет, но вдруг. Цитата:

    "....Удлиннение крыла - отношение квадрата размаха крыла l к площади крыла S: лямбда = l^2/S; характеризует степень вытянутости крыла вдоль размаха. Для прямоугольных крыльев лямбда = l/b, где b - хорда крыла. УК - один из основных геом. параметров крыла, определяющих его аэродинамические характеристики. При малых дозвуковых скоростях полета несущий свойства эллиптич. крыла большого удлиннения определяются соотношением: C с индексом y^альфа = 2*пи*лямбда/(лямбда + 2) (см. Аэродинамические коэффициенты), а его индуктивное сопротивление Х с индексом i при заданном значении коэф. подъемной силы С с индексом y обратно пропорционально лямбда. Т.о. при увеличении лямбда несущие свойства крыла возрастают, а Х с индексом i уменьшается и соответственно растет максимальное аэродинамическое качество. Однако удлиннение крыла, как правило, ведет к не пропорциональонму росту его массы из-за необходимости обеспечить надлежащие прочность и жесткость крыла. У рекорднах планеров значение лямбда достигает 40; у дозвуковых пассажирских самолетов 80-х гг. лямбда = 7-10 (напр., у самолета Ил-96-300 лямбда = 9,5)"

    Конец цитаты.
    Источник: Энциклопедия "Авиация" изд. "Большая российская энциклопедия" 1994

    Оттуда же краткая цитаты:
    "Аэродинамическое качество - отношение подъемной силы к сопротивлению аэродинамическому......Для самолета, совершающего горизонтальный установившийся полет при малом угле атаки.....: К = G/T, т.е. представляет отношение веса самолета к тяге и характеризует экономичность самолета....."

    Я не авиаспециалист, но я понял вот что:
    1. На маневренность непосредственно влияет подъемная сила, создающая перегрузку, которая, собственно, и является мерой маневренности. Иными словами - говорим подъемная сила, подразумеваем маневренность.
    2. Подъемная сила - это скорость + площадь крыла + профиль (его, вероятно, в большинстве случаев ВБ следует опустить)
    3. Удлиннение ПРЯМО на подъемную силу НЕ влияет.
    4. Удлиннение показывает, на сколько самолет хорошо самолет держится в воздухе, насколько эффективно он использует скорость для создания подъемной силы.

    Отсюда делаю выводы (не учитывая компрессии):
    1. Чем больше скорость - тем больше подъемная сила, а значит и меньше возможный радиус поворота.
    2. Чем больше площадь крыла - тем больше подъемная сила - тем меньше радиус разворота (для сравнения площадей у разных самолетов берется нагрузка на крыло)
    3. Чем больше удлиннение - тем меньше скорость сваливания, и, следовательно, тем меньше может быть возможная скорость устоявшегося виража (радиус не важен).

    Это подтвержается реалом, посмотрите, какие скорости заявляются в качестве сталловых для П-38. А теперь предствьте МиГ-21 с малым удлиннением - какая у него скорость сваливания? И отсюда же У-2 (американский разведчик), имеющий крыло огромного удлиннения, может лететь в разряженной стратосфере со скоростью около 700км/ч. Вспомните так же птиц (например чаек и воробьев) какие у них удлиннения и как они летают, а также планеры, ведь они могут летать на скоростях чуть ли не в 20км/ч :), благодаря большому удлиннению.

    Остюда, касательно П-38 и, имея ввиду его огромное удлиннение, может действительно уменьшить ему скорость стала? Мне кажется, что в РЛ у него был довольно большой радиус разворота из-за высокой нагрузки на крыло, но при этом очень низкая скорость сваливания. Тем более посмотрите на результаты тестирования: пилоту рекомендуется держать скорость как можно ниже и при это еще и климбить, чтобы переманеврить 190 - ведь 190 со своим крылом малого удлиннения уже фактически находится на грани сталла, когда у 38 еще еще небольшой запас устойчивости.

    КОРТКО ГОВОРЯ: Удлиннение прямо влияет на скорость сталла, чем больше удлиннение - тем меньше возможная скорость и косвенно на подъемную силу - чем больше, тем больше.


    Это, ессно, все мои измышления. Интересно было бы услышать спецов....