P-38 Bugged

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

  1. -ALW-

    -ALW- Well-Known Member

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    Here is some data showing the range of types and how many were made as well as their performances.
     

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  2. -ALW-

    -ALW- Well-Known Member

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    RGREAT:
    Having gone this far into the discussion, I feel that I have made 2 steps forward and 200 steps back so I am coming from a different approach now.
    The root of the problem I will explain here is from the basic lack of performance in the P-38. It is obvious from many hours of flying the aircraft that I discovered the P-38, regardless of variants differ too much from the facts and information found/discovered. The big differences are in the top speeds.
    I found from some quick testing that the P-38 fails miserably in this area. I feel that if basic specifications and data, if used for a foundation within WB programming can achieve normal or ?realistic? values.


    I will add more later. I am collecting information and will post more as I organize what I have. Pictures of the books I'm sourcing my information:
     

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  3. zxszxs

    zxszxs Banned

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    plz do!
    it'd be appreciated if u posted some first-hand info on p51/p47 and other american warbirds too (especially their hi-alt performance that's missing in wb)
     
  4. HoHun

    HoHun FH Beta Tester

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    Hi ALW,

    >The big differences are in the top speeds.

    Do you have a speed over altitude curve for the P-38F?

    I've found one for the P-38J only, and at least that one seems to be matched well by the FH P-38J.

    Regards,

    Henning (HoHun)
     
  5. -ALW-

    -ALW- Well-Known Member

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    The F variant for some reason is somewhat difficult to get info on but I will try. I think that variant should be dropped in any case as the preceding variant (G/F-5A) has many more produced with better performances but I don't think you'll find much difference. The speed chart previous here showed only a difference by 5mph.

    I'll look for and post what I think you're asking for.
     
  6. -ALW-

    -ALW- Well-Known Member

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    BTW...does the climb rates interest you or apply for what you are testing? I do have detailed info on that.
     
  7. HoHun

    HoHun FH Beta Tester

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    Hi ALW,

    >BTW...does the climb rates interest you or apply for what you are testing? I do have detailed info on that.

    I've got a climb rate chart for the P-38J, too, but haven't tested the Freehost plane yet for comparison.

    For the P-38F, I've got nothing, so any information would be appreciated! :) Climb rate is just as important as top speed.

    Regards,

    Henning (HoHun)
     
  8. -ALW-

    -ALW- Well-Known Member

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    Ok, I'm trying to find the info for the F model, but I'm having no luck at the moment either. I wouldn't miss the F anyhow, as the G model has more than twice it's kind produced (1,082).
    What series info I have at moment are: the P-38H, P-38J, P-38L-1, P-38L-5, and F-5B.
     
    Last edited: Apr 1, 2003
  9. -ALW-

    -ALW- Well-Known Member

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    __________Maneuverability__________

    Since this is going slow in progress, I'll post something new.

    Maneuverability

    Tonight after flying a mission I referred to a page 28 in the Pilot's Training Manual for P-38's.
    The image below gives a very obvious difference to the maneuverability of the P-38. I would go by these facts because it is what the pilots were given as a reference at that time. I don't think that this information would have been false; otherwise what would be the point? Maneuverability for the P-38 on WBFH is unacceptable in my analysis because of all the facts and information I have. The maneuverability we had before these updates was good and acceptable!!!!

    :cheers:
     

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  10. Bobby

    Bobby Well-Known Member

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    Sorry my english.
    Training Manual for P-38's avalable in internet?
     
  11. Comet-

    Comet- Well-Known Member

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    First, I don't want to sound as whiner. It is not meant to, I just have hard time trying to understand, why FH developers reduced P38 to the current state.

    *nonimportnant rant mode on*
    I am also conviced that current P-38 is totally off. This is hardly aircraft which outmanouvered P51 and P47 in many mock dogfights, which could even manouver with Spitfire VIII (as in another test). Lol, veteran pilot saw P38L in Aces High and said it was lot worse than real one... and our P38 is totally outclassed by AH version. Only think it does now is somewhat good acceleration, climb rate and zoom climb. Handling is same as Mosquito....almost as same. It turns worse than Fw190a4 light (21.5s for Fw, 23s for P38, fuel 50%, 1km alt) and same as normal version, every 109 can easily outturn it now, except planes with underwing cannons.
    *nonimportnant rant mode off*.

    I spend some time looking for the solution of this problem. Data about wingloading and power loading were pretty miserable, and I couldn't understand, how such a/c was one of the most manouverable aircrafts in the war... (well, versions with boosted controls at least). I didn't find anything about turn rate tests, but I still didn't contant one possible source, so we will see.

    I am pretty much sure that P38 is impossible to model in WB based only on those raw data about weight, HP, wing area, etc.
    For example, how this aircraft with such terrible power loading and wingloading can be one of the best climbing planes in the game? Climb to the 20k at little more than 5 minutes is terrific...

    There are many unique characteristics. Article posted today at AGW board by Dobs was exactly one of the rare sources about its unique features.

    Compressibility
    - Compressibility wasn't a problem under 25k. That is probably impossible to solve, as WB FM is totall BS in this area, exactly opposite of what it should be.

    Very light control forces
    - control forces were very light, especially on the elevator and rudder (out of the compression, of course :). Our P38 has very very heavy elevator at all speeds, it is nearly impossible to pull more than 4-5G without full use of elevator trim. Ailerons are imho correct.

    Aspect ratio
    - Aspect ratio of its wing was over 8, compared to 6 of the average fighter. It's wings produced less drag in turns compared to the other aircrafts, partially compensating for its high-wing loading. It also allowed better climb and ceiling.

    Taper Ratio
    Width of wingtips was 1/3 of the width near wingroots. That improved roll rate over the classic 1/2 ratio of the other aircrafts.

    Very efficient thrust
    Efficiency of two 1450HP engines isn't equal to the one 2900HP engine. It is a lot better. P-38 is using two large and efficient propellers with much greater totall area. It converted its power to thrust a lot better than normal single propelled a/c.

    Stability - ok
    well, our plane is definitely stable as rock, nothing wrong here :)

    Excelent handling at higher AoA - probably ok
    It is good? I don't know, I don't have that much experience in P38. I can't say there is a problem, there are much severe bugs now overshadowing this.

    !!!! Stall Speed !!!!
    This is worst bug in the current P38, and very easy to prove. Most probably it is also responsible for terrible reduction of manouverability, especially at low speed, where only light japanese aircrafts could compete.

    Pilot manual for the P-38L clearly states that stall speed of aircraft with flaps and gear up is 94mph (increasing to the 105mph depending on the load). With full flaps and gear down, stall speed is 69mph (78 mph fully loaded). This is only my assumption, but I think that if the 94mph is stall speed for clean aircraft, with Fowler flaps in Manouver position it will be between 80-90mph.

    Current P38L in WB with 10% fuel stalls at 120mph. First and second degree of flaps will reduce stall speed each by 5 mph to the 110mph. Full flaps reduce stall speed to the 100mph.

    Fact is that our P38 has 20-30mph higher stall speed than it should have. That is SEVERE degradation of the manouvering capability of the aircraft. It is also one single error in FH WB P38, for we have a real numbers. What about reducing stall speed to the correct values?
    Everything else is matter of opininon, and I can't bring exact numbers, with exception of calculated values, which are difficult, as I don't know exact power ratings of its Allison engines at all altitudes.
     
  12. HoHun

    HoHun FH Beta Tester

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    Hi Comet,

    >First, I don't want to sound as whiner.

    I know you are a serious player, it's always a pleasure to fly with you! :)

    >Pilot manual for the P-38L clearly states that stall speed of aircraft with flaps and gear up is 94mph (increasing to the 105mph depending on the load). With full flaps and gear down, stall speed is 69mph (78 mph fully loaded).

    One thing to take into account is position error (airspeed indicator calibration). Depending on airspeed, angle of attack and position of the pitot tube, the airspeed indicator usually gives wrong readings. Usually, it reads too low at low speeds so that the 94 mph clean stall speed might actually be 104 mph for example.

    Pilots' manuals often give a position error table (or curve) to correct the readings to calibrated IAS. The P-38 manual perhaps has one, too. (If such a table is given, it often fails to cover the very low speeds that are especially interesting for us. This is for example the case with the Spitfire manuals.)

    If you could check this source of error with the help of the manual and arrive at a calibrated IAS number for stall speed, we'd have an important data point to check the Freehost P-38 against.

    I think I've seen a HTML version of the P-38 manual on a web page once, but unfortunately, no position error table was given else I might have been able to provide this information right away.

    Regards,

    Henning (HoHun)
     
  13. rgreat

    rgreat FH Developer

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    Waiting for fact with sources (quotes/graphs).

    For now i can only see assertions without the proofs, or therorys i cant analyse and use correct.

    P.S. No offense.
     
  14. Comet-

    Comet- Well-Known Member

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    Hi Hohun, Rgreat.

    I found the PDF version of the manual, with pictures and tables missing from the html version. It is here. Btw it is very good and detailed manual, a lot better than manuals for Spitfire or 109, in my opinion at least :).

    This is table for IAS correction in the book.
    [​IMG]

    Additional info about very low speed handling is in the manual, take-off and landing procedures. On the take-off P-38 can lift to the air at 90-100mph (flaps not necessary) with 120mph considered safe speed.
    When landing, plane with flaps at manouver position (8°) and gears down slowed down to 120mph, then with full flaps slowed under 110mph, and then flared off at 80mph until the contact.
     
    Last edited: Apr 23, 2003
  15. -exec-

    -exec- FH Consultant

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  16. Bobby

    Bobby Well-Known Member

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    exeс
    http://www.geocities.com/ramjetpub/
    Вот зараза. Сначала страница загрузилать, а потом ошибки пошли :(
    Там pdf с таблицами на 14 листов. P-38Chart.pdf
     
    Last edited: Apr 23, 2003
  17. Comet-

    Comet- Well-Known Member

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    Hi exec,

    Both parts are on their way, P-38pilot.pdf and P-38charts.pdf.

    Thx Bobby, I didn't know about other documents.

    ----

    Link is not dead, damned server is overloaded. I used Getright and after some time it downloaded everything, IE wasn't able to download it, or it downloaded only small part of it.
     
  18. -exec-

    -exec- FH Consultant

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    Last edited: Apr 23, 2003
  19. HoHun

    HoHun FH Beta Tester

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    Hi Comet,

    thanks, that's great data! :)

    An example on how to read the correction table: If clean stall speed is given as 94 mph (just quoting your post here), that's right in the middle between the listed values of 83 and 106 mph IAS in the "clean" column and translates into 109 - 110 mph in the CAS column.

    So if the P-38L stalls in Warbirds at 120 mph (I haven't checked this), it wouldn't mean that's 26 mph too fast but only 10 - 11 mph. Still good for an improvement, though :)

    >On the take-off P-38 can lift to the air at 90-100mph (flaps not necessary) with 120mph considered safe speed.

    Flight near the ground benefits from ground effect, so these numbers aren't directly applicable for free flight.

    Regards,

    Henning (HoHun)
     
  20. rgreat

    rgreat FH Developer

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    Looks like good info, ill check it little later.