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View Diary: Cold War Relics - TU-95 Bear (67 comments)

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  •  I looked it up too (5+ / 0-)

    With limited time I found this somewhat enlightening, but the engineering jargon is a little over my head.

    The respondents confirmed the props are counter- rather than contra-.

    I get it when the subject is aircraft control, especially if #4 quits.  V2 would be ridiculously high.  I just don't get why it works.

    TEA PARTIES: Something little girls do with their imaginary friends.
    (-6.75 -6.51)

    by flygrrl on Tue Jan 07, 2014 at 01:35:34 PM PST

    [ Parent ]

    •  Contra-rotating, Not Counter-Rotating (5+ / 0-)

      You might want to reread that site.  Counter-rotating refers to when the designer places engines rotating in the opposite direction on the same wing or opposite wings to offset the torque being produced by the rotating prop.  Otherwise, the airframe designe needs to offset the torque and vortex flows with trim tabs and mechanical stablizers, thereby increasing drag and reducing performance.  Most of the experience with contra-rotating props has been with turbo-props in order to absorb the power availabe without having overly long props.  Much of that experience was with early turbo-props as well (particularly in the US), such as the infamous Republic XF-84H "Thunderscreech" research aircraft.  It did not use a contra-rotating prop and experienced considerable flight stability issues as a result.  The same engine used in the XF-84H was used in the Douglas A2D Skyshark, which sported a contra-rotating prop but a failure-prone gearbox as well.  Other aircraft of note using this engine and geartrain included the vertical take-off/vertical-landing designs, the Lockheed XFV and the Convair XFY Pogo.  Interestingly, both the French Navy and the Roayl Navy in the 1950s used turbo-prop powered aircraft with contra-rotating props in the ASW role, the Breguet_Aliz%C3%A9 and the Fairey Gannet respectively.  The 1950s was an exciting period in aircraft design.

      "Love the Truth, defend the Truth, speak the Truth, and hear the Truth" - Jan Hus, d.1415 CE

      by PrahaPartizan on Tue Jan 07, 2014 at 02:11:14 PM PST

      [ Parent ]

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