Wai Chung asked in 汽車及交通飛機 · 1 decade ago

點解有D直昇機沒有後面的螺旋翼又唔會打轉

點解有D直昇機沒有後面的螺旋翼而又可以保持直昇機唔會打轉?例如:London air ambulance

http://www.freefoto.com/preview/28-22-1?ffid=28-22...

2 Answers

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  • 1 decade ago
    Favorite Answer

    The Helicopter in question is MD-902, that comes with a boeing new NOTAR technology. NOTAR stand for NO TAil Rotor. And IT HAS NOTHING TO DO WITH THE TAIL FIN

    I shall show you this drawing, that explain how NOTAR work

    圖片參考:http://upload.wikimedia.org/wikipedia/commons/3/32...

    The key is the Jet Exhaust System, as point 18 in the diagram. It exhaused the turbulance for which counter the main rotor air flow.

    The motion know as Coandă effect, which is a fluid dymanic thing, i cannot explain that untill i give you a defined lecture on Fluid Dynamic. Which i am not planning on doing it.

    Basically, the jet stream created by the tail rotor will attact the nearby air and suck into the tail boom, and to compensate this, the air will offer a equally strong reaction force to resist the pull, thus pulling the torque away from the tail boom.

    This is however, an experimental design and some expert say it cannot function well with thin air or low turbulance. And there have been some incident with such model in 2008 (Also with London Air Ambulance.)

    Source(s): My Brother fix aircraft for boeing.......
  • wilson
    Lv 7
    1 decade ago

    without knowing the details of design, i advise you to note the two tail vertical fins.

    2009-10-03 12:53:46 補充:

    without knowing the details of design, i advise you noting the two tail vertical fins.

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