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胖寶 asked in 汽車與交通航空器 · 1 decade ago

請問升力與誘導阻力的關係?

在揭開飛行的奧秘一書中提到,攻角越小,誘導阻力也變的越小,升力就接近空氣動力。所以升力與誘導阻力成反比。P3-11

但後面又提到,升力增加,誘導阻力也增加。P3-15 / p5-3

請問升力跟誘導阻力的關係究竟為何?

(請勿介紹飛行中遇見之阻力,已知)

非常感謝

Update:

所以我才拿上來發問咩~

Update 2:

所以綜合Mason與Tony的說法,升力與誘導阻力是成正比的,在攻角未到失速角之前都是正比。

不過請教Tony, 251頁的那個公式我看不懂呀! 而且印象中展旋比越大,升力越大呀! 怎麼會是反比呢?

3 Answers

Rating
  • Mason
    Lv 7
    1 decade ago
    Favorite Answer

    In aerodynamics, lift-induced drag, induced drag, vortex drag, or sometimes drag due to lift, is a drag force that occurs whenever a moving object redirects the airflow coming at it. This drag force occurs in airplanes due to wings or a lifting body redirecting air to cause lift and also in cars with airfoil wings that redirect air to cause a downforce. With other parameters remaining the same, as the angle of attack increases, induced drag increases.[

    上述文字敘述來自維基百科!最後一句,攻角增加、誘導阻力也增加。攻角增加,升力一定增加,一直到失速的攻角,之後升力反而會減少!

    有個網站(英文)專門探討誘導阻力:http://selair.selkirk.bc.ca/Training/aerodynamics/...

    圖片參考:http://www.toandfromtheairport.com/lightaircraft/I...

    2009-04-15 17:16:45 補充:

    http://en.wikipedia.org/wiki/Induced_drag

    唯基百科的解釋!

  • Tony
    Lv 7
    1 decade ago

    親愛的 小玉,

    在1984年版的Fundamentals of Aerodynamics寫道:

    induced drag is frequently called the drag due to lift.-->246頁

    the induced drag coefficient increases rapidly as CL increase-->246頁

    CDi=CL^2/(πeAR)-->251頁.

    所以誘導阻力係數CDi和升力係數CL的平方成正比, 和展弦比AR成反比.

    2009-04-16 22:54:16 補充:

    您還是沒讀通, Mason和Tony都沒說過「升力與誘導阻力成正比」這樣的話.

    Mason: 攻角增加、誘導阻力也增加。攻角增加,升力一定增加

    Tony: 誘導阻力係數CDi和升力係數CL的平方成正比.

    Mason以攻角為出發點, 當攻角增加, 誘導阻力增加, 升力也增加, 從頭到尾都沒出現「正比」兩字.

    Tony以數學式為出發點, 只說誘導阻力係數而不說阻力, 只說升力係數而不說升力, 說的也是「平方成正比」而不是「一次方成正比」.

    您想在民航特考拿高分, 就要用字精確.

    2009-04-16 22:58:55 補充:

    若對251頁的那個公式有疑問, 請看1984年版的Fundamentals of Aerodynamics. 這本書從246頁到251頁都在講誘導阻力, 內容太多, 且有許多數學式, 不便在網上打字回答.

    Source(s): C'est moi.
  • 1 decade ago

    理論矛盾

    理論有問題

    怎麼可能同時是正比和反比呢?

    那飛機怎麼開?

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