Location of wings

Discussion in 'Aviation' started by Thorlifter, Aug 5, 2010.

  1. Thorlifter

    Thorlifter Well-Known Member

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    What advantage/disadvantage does the location of the wings offer, such as mounted low, mid, or high on the fuselage?
     
  2. Smoke

    Smoke Member

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    High wing should be more stable and it can clear ground obstacles better. Low wing should be more maneuverable and take of slightly quicker.

    Of course, these are gross generalizations.
     
  3. Crimea_River

    Crimea_River Well-Known Member

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    High wing allows fuselage CG to be below the wing so there's a general tendency for self leveling from bank position. Also you can see down better. Disadvantage - landing gear usually needs to be supported from fuselage, therefore tends to be narrow.
     
  4. drgondog

    drgondog Well-Known Member

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    You select based on mission specs.

    If you are looking for cargo garrying as primary use, the high wing permits un interupted floor and better visibility downward (in general), and for short field/rough field applications the high wing/engine combo eats fewer rocks. Most STOL/military cargo ships have a high wing/engine mount for these reasons.
     
  5. timshatz

    timshatz Active Member

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    Good question. All the answers already tossed up cover most of the details. I would add that pilots tend to be "High Wing" or "Low Wing" fans. Once they get that way, they usually don't change unless they have to. At least amongst Civilian Pilots anyway.

    One of the lines I've heard from High Wing directed a Low Wing is that Low Wings are inherently unstable, with the weight and details above the wing (true or not doesn't matter, it's hanger flying talk). They say if Low Wings are an aboration of nature. Example? Have you ever seen a low wing bird?
     
  6. Shortround6

    Shortround6 Well-Known Member

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    Mid-wing has the least drag but attaching the wing at the mid point causes the most disruption of interior space as the spars go through.
     
  7. Crimea_River

    Crimea_River Well-Known Member

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    Why would that be? Drag is the product of drag coefficent and surface area. Assuming suface area equal, why the Cd be better on a mid wing?
     
  8. drgondog

    drgondog Well-Known Member

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    No position of a wing is really much of a factor in true stability. adding dihedral to a low mounted wing does however improve rolling moments, particularly at low speed, and all things being equal the high wing may be slightly better relative to roliing stability

    The a/c with low wing and high wing present easier and lighter solutions for carry through stucture for the wing, as mid wing usually requires a bulkhead or 'ring' to provide beam continuity. Most early US jet fighters were low wing because of front intake and ducting to engines. Most early jet bombers were high wing due to engine pods and internal bomb bays. Both enabled spar continuity at least to CL. As the wings moved up to center/center high (F-104 and F-105) the ducting was more efficient (two smaller diameter ducts on side versus one big ass one down the centerline) and better solutions for a wing carry through structure were available due to the smaller ducting.

    Sweeping a wing causes more stability issues than placement of the wing.

    When twin engines dominated the design requirements, the engines were more or less separated from the wing (i.e. semi pods offset from centerline) and no longer required front to rear annular ducting for the interior mounted engine... thus the F-14, F-15, F22 were generally designed with mid to mid high wing position that did not have to factor an central ducting for engine intake or engine mounts.

    I would have to think about a blanket concept that mid wing has less drag, however.
     
  9. Messy1

    Messy1 Well-Known Member

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    Great info guys, thanks. Very interesting.
     
  10. davparlr

    davparlr Well-Known Member

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    I’ll talk about fighters and start off with the mid-wing designs. Mid –wing design allows for optimum connection between the wing and fuselage and represents the lowest drag configuration. It also basically has neutral stability, an advantage for fighters. Disadvantages are manufacturing difficulties, complex internal design to hold the mid-wing spar, and more complex landing gear. Some examples are F4F, F11F, Mig 15, and F-16. This design was never very popular and pretty well disappeared by 1960.

    The low wing design is unstable since the center of lift is typically below the center of gravity. This is desirable for fighters in that it allows a higher level of maneuverability. In addition to the unstable design, I think the main advantage is ease of manufacture and simplicity of landing gear design. Disadvantages are some drag inefficiencies, difficulty in handling underwing stores and in access to some fuselage mounted equipment. This, by far, is the most popular design from WWII to post 1960. Some examples are most WWII fighters, F-86, and F-4 Phantom II. Most early low wing fighters seem to have had to correct for some rolling instability by utilizing dihedral, upsweep, wings. Maybe not.

    The high wing design is the most stable and, except for the F8U, has been generally avoided in fighter design up until late 1960s. Landing gear design was also a drawback. With advent of fly-by-wire flight controls in the late 60s and its associated artificial stability, wing placement became non-relevant for stability purposes. Most post 1970 fighters had high wings, most likely to ease underwing stores handling and fuselage mounted equipment maintenance, but later blended wing designs like the F-22 and F-35 make it more difficult to tell where the heck the wing is but appear to be going back to mid-wing. Carrying stores internally also drives the design. Some aircraft with high wings are the before mentioned F8U, which uses anhedral, downsweeping, wings possibly to decrease rolling stability, F-14, and F-15.

    Anybody want to correct anything, please do so.
     
  11. drgondog

    drgondog Well-Known Member

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    Dave/Shortround - I'm having a 'blank' regarding drag charcteristics of midwing vs high or low. I don't have access to any of my textbooks and reference materials at the moment - to refresh whatever memory I have left - but one thing is pretty clear to me.

    The advanced theories regarding wing/body interactions weren't even remotely fleshed out in the early 60's so the theoretical fluid mechanics basis wasn't in use during the 30's and 40's. Karamcheti (sp?) was one of the pioneers but his theoretical applications wern't practical until advanced relaxation methodology and more powerful computers like the CDC6600 were available in the late 60's

    So, what are your thoughts regarding why designers of the 30's and 40's believed mid wing was optimal for lowest drag?

    Some obscure thoughts regarding form drag component? Nothing else I can think of would influence the total parasite drag buildup based on wing body geometry.
     
  12. Milosh

    Milosh Well-Known Member

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    I thought a plus for the F4U was its wing/fuselage attachment or was it only later that this was found to be a drag reducing feature?
     
  13. Shortround6

    Shortround6 Well-Known Member

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    It was thought that the wing meeting the fuselage at a 90 degree angle would cause the least amount of drag.

    I don't know who started it or why but a look most mid-wing aircraft shows either no wing root fillet or a minimal one in comparison to many low wing aircraft and a few high wing ones.
    Some people claim that is why the Corsair had the gull wing. It wings meet the fuselage at 90 degrees or close to it.

    It might have given the same drag as a low wing plane with the fillet but without the manufacturing difficulties of making the fillet. On the other hand it often resulted in a more complicated landing gear (aside from fixed landing gear planes) than the low wing position.
     
  14. drgondog

    drgondog Well-Known Member

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    After the fact, (as I sure wasn't consulted) the F4U appears to have a couple of key design factors leading to the Gull wing.

    1. Big prop and engine led to considering low wing.
    2. Range considerations forced fuel cells into the wings making gear retract an interesting test of creativity. Needed short gear because couldn't retract outboard and long enough gear to clear prop meant reducing fuel in wings (for outboard retract) or forcing armament outboard of gear structure, further reducing fuel.
    3. Gull wing to try to solve 'short gear - retract chordwise rather than span wise. Solve fuel cell issue, solve prop clearance issue.

    not sure the wing 'direction' from fuse was dictated by aerodynamics - more a restriction based on few remaining places to hang the damn thing.

    Strictly opinion.
     
  15. davparlr

    davparlr Well-Known Member

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    Well, mid wing makes the optimum 90 degree interface easier. 90 degrees provides to lowest interference drag of a simple plane intercept, although my book, which was so old it had propeller fighters as reference, is lost. I did find one reference that did reflect this, " High Wing or Low Wing?". Mid-wing by itself would have no impact on drag, only the angle of intercept, thus the advantage of the gull wing on the F4U. I do not think it was a major impact since most of the really high performance fighters didn't bother with the 90 degree intercept.
     
  16. Shortround6

    Shortround6 Well-Known Member

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    Wind tunnel work and wool tuft flow pattern work?

    try:

    http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091613_1993091613.pdf

    For one study with this from page 28;

    The usual high-wing positions
    may be made nearly as favorable as the high mid-wing
    positions by the use of suitable fillets. Forward
    positions of the wing with respect to the fuselage
    appear to be favorable. Low-wing positions are
    unfavorable, but, by adequately filleting the wingfuselage
    juncture, the aerodynamic efficiency of the
    low-wing combinations can be made to approach that
    of the better high-wing combinations.
    In general, it may be noted that important.

    This study report is from 1936 and further additions to the study were made in 1937 and 1938.
     
  17. davparlr

    davparlr Well-Known Member

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    Very interesting. It was also interesting that they only tested circular body wing placement and did not test angle intercept to fuselage other than where wing met circular body. This would not aided Vought in their analysis of the F4U wing performance. Vought probably did their own testing.
     
  18. VG-33

    VG-33 Banned

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    #18 VG-33, Aug 8, 2010
    Last edited: Aug 9, 2010
    True, but the drag coefficent is depending from the object's shape.

    First, due to the pressure gradient distribution, the mid-wing configuration makes a less draggy coef, from itself.

    Second, the total wing + fuselage assembled altogether drag is higher than arithmetic separate values for both components.
    Total drag = wing drag + fuselage drag + interference drag. To reduce the last one, you use Karman fairings. Assuming even some (little) drag loss due surface increase, you win anyway more at the end, on drag coef reducing. The last one being significant.

    They are much more efficient ( they =Karmans) on rounded or oval section fuselage in mid wing position also, than on the others formulas.

    Third, all that jobs were maid in wind tunnels since early twenties, more that enough times. All results are published (by Eiffel, Göttingen, ONERA, TsAGuI centers ...) and available in much specialised scientific highschool libraries.

    It's not a big secret/discovery. Maybe searching at the NACA site you can browse values on the WEB.

    Regards.
     
  19. Colin1

    Colin1 Active Member

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    How much
    interference drag did the F4U design incur?
     
  20. VG-33

    VG-33 Banned

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    The gull-wing or Pulawski wing was used since the 20 ies. The Corsair wing is just an inverted Pulawski wing.

    Gull wing - Wikipedia, the free encyclopedia

    It was used well before the american naval fighter.

    ??????? ?????-7

    Regards
     
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