How did Newton explain the flight of birds?

Discussion in 'Physics & Math' started by thothnabu, May 21, 2006.

  1. thothnabu Registered Senior Member

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    How did Newton explain the bird's resistance to gravity if the theory of aerodynamics didn't exist yet?
     
    Last edited: May 21, 2006
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  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    I have read major parts of two of Newton's books (Principle of... & Optics) and do not recall him commenting on this question.

    I am not sure what you mean by the "theory of aerodynamics" or by "explain." I suspect that he, as the Greeks before him, had some non-mathematical "explanation" - probably about as good as mine and quite similar to mine. (I have had the benefit of a aerodynamics course, as undergraduate, at a very high level with half the class being graduate students, as professor was very good.) So my explanation might throw out a few terms (tip vortices, non-zero curls, Bernouli Eqs., etc.) Course focused more on stream line flow in water and air foils, but most of it I have forgotten.

    All I remember from the lectures on turbulence was the amazing scale variation in which some of the mainly empirical laws apply, plus the end part of a stupid little poem that summed up this cascade of energy* down to ever smaller scales:

    "....
    and on these fleas, live little mites that bite em,
    and on their backs, live smaller mites to spite em,
    and so it goes, on and on and on, ad infinitum."


    So in the final analysis, even if Newton did not have (and He may have had) a mathematical formulation / approximation for a very complex problem, I think he knew how birds fly - and even in the quantative sense that the air is given momentum downwards by the action of their wings to produce this downward momentum, which is equal to gravity force in level flight.
    ------------------------------------
    *In the atmosphere, hurricanes spinning off tornadoes is where this cascade begins. It ends when the atomic nature of matter begins to be apparent.
     
    Last edited by a moderator: May 21, 2006
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  5. CANGAS Registered Senior Member

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    Admitting that BillyT is right about something is as much fun for me as going to the all night dentist.

    He's got it. The downwash of air by the wing is acknowledged to be the active agent in aerodynamic flight. With his prodigious I.Q., he surely knew (Newton) that action/reaction had to be working for birds. And after having seen anything ever blown into the air by a strong wind, he had it figured out in the general principle.

    Aerodynamicists have said that aerodynamics is exact mathematical science. Partly. The other half is black magic voodoo.
     
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