McDonnell XP-67 Moonbat

Discussion in 'Aircraft Pictures' started by Snautzer01, Sep 27, 2016.

  1. Snautzer01

    Snautzer01 Well-Known Member

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  2. Wurger

    Wurger Siggy Master
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  3. Old Wizard

    Old Wizard Well-Known Member

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  4. michaelmaltby

    michaelmaltby Well-Known Member

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    beautiful aircraft ....
     
  5. wuzak

    wuzak Well-Known Member

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    Pity about the engines.

    I wonder what could have been made of the XP-67 with V-1710s and turbos rather than the IV-1430s.

    In terms of performance, the XP-67 was very close/similar to the Lockheed XP-49, which also used turbo IV-1430s and was basically a tidied up P-38.
     
  6. Capt. Vick

    Capt. Vick Well-Known Member

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    Really? I'm not so sure with all that parasitic drag from all the blended surface area.

    Anyway, here is a picture of it after the engine fire:

    images (1).jpg
     
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  7. wuzak

    wuzak Well-Known Member

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    Yes, though it appears the XP-67 peak speed was at a higher altitude.

    McDonnell XP-67 - Wikipedia, the free encyclopedia
    Lockheed XP-49 - Wikipedia, the free encyclopedia

    Interestingly they quote 1600hp for the XP-49 and 1350hp for the XP-67 engines, but the reality was that neither was likely to have much more than 1000hp available from teh engines during their test flights.

    Nice picture. I hadn't seen that before.
     
  8. wuzak

    wuzak Well-Known Member

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    I posted a few videos of teh XP-67 in the video section.

    XP-67 Newsreel
     
  9. Wunburra

    Wunburra New Member

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    To me the McDonnell "Phantom" looked like it was an XP-67 with engines replaced by jets. All be it in a different position of course. But definitely very similar.
     
  10. Thud-Dud89

    Thud-Dud89 New Member

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    Definitely gives away the family origins, plus if it was angular and not curved, it would start to resemble an early F2H Banshee.
     
  11. XBe02Drvr

    XBe02Drvr Active Member

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    Hey Cap'n, ever hear of interference drag? Happens when you bring two surfaces together at a sharp angle, as in fuselage/wing/nacelle. Increases dramatically as your (subsonic) mach number rises. In a go-fast high flier like the Moonbat the drag from the additional wetted area is more than offset by the reduction in interference drag, the delayed onset of transonic shockwaves, and the additional lift those blended airfoils provide. It's all about lift-over-drag, man.
    Wonder what she would have done with decent engines. Pair of Darts, anyone?
     
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  12. Gnomey

    Gnomey World Travelling Doctor
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    Good shots!
     
  13. Capt. Vick

    Capt. Vick Well-Known Member

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    Not sure what your driving at here friend. Are you saying the lack of something ("interference drag") means the lack of something else (parasitic drag)? No sure I understand your argument if that's what you mean.
     
  14. wuzak

    wuzak Well-Known Member

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    I think he is saying the extra parasitic drag from the extra surface area is less then the reduction in interference drag, meaning that overall it will give lower drag.

    Wasn't the interference drag part of the reason the Corsair went to the inverted gull wing? The 90° junction was though to give lower drag.
     
  15. XBe02Drvr

    XBe02Drvr Active Member

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    Hey Cap'n, Wuzak's right. The reduction in interference drag (which is part of parasitic drag) more than compensates for the parasitic drag from the greater wetted surface. In addition, the airfoil shape of the blended fairings contributes more lift than it does drag, which only really works due to the laminar flow nature of the structure.
    I read somewhere that the Corsair's gull wing was the result of having to have a short enough gear leg to fit in the wing structure, but have enough ground clearance for the propeller. The savings in interference drag I believe was a happy by-product.
     
  16. Capt. Vick

    Capt. Vick Well-Known Member

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    You may be right, and I'm not saying you're not, but unless you can produce some sort of data to support your statements regarding this particular aircraft, than my friend, you are just blowing smoke. I honestly don't see how you could support the following two claims without access to period test reports, even if they DID address these two issues specifically.

    1) The reduction in interference drag (which is part of parasitic drag) more than compensates for the parasitic drag from the greater wetted surface.

    2) In addition, the airfoil shape of the blended fairings contributes more lift than it does drag, which only really works due to the laminar flow nature of the structure.

    My original statement about parasitic drag was just a half-assed observation based only on my general aviation knowledge and college studies, both of which have suffered due to the passage of time. :lol:
     
  17. XBe02Drvr

    XBe02Drvr Active Member

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    Well Cap'n, it appears your "half-assed observation" was right on the money. In digging a little deeper on this, it seems that the advanced concepts in this case didn't pan out in real-world performance. We could argue til the cows come home about "what if" the 'bat had ever had the thrust to reach the speed regime for which it was designed, but fact is, it didn't happen. 1200 HP shy of design power is a pretty big deficit to overcome. At the higher angles of attack that the slower speeds entail, the wetted area parasite drag of the blended fairings becomes more significant; the savings in interference drag less so.
    Seems McDonnell was cheated in the engine department over and over again. Not until the days of the Voodoo and the Phantom II, did he ever get engines for his planes that delivered their design thrust.
     
  18. johnbr

    johnbr Well-Known Member

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    Xp-67.jpg
     
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  19. Wurger

    Wurger Siggy Master
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  20. Old Wizard

    Old Wizard Well-Known Member

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