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Re: WING FEATHER ATTACHMENT




ptnorton@msn.com wrote:

> Robert Kiely wrote:>Interesting, perhaps Dromaeosaurs used a thrusting
> motion to give it more
> speed when chasing/pouncing on prey< This is what I tend to believe,
> and is very much along the lines of the "pouncing proavis" model
> (PTN)
>
>
> >>I have some doubts about the extra running speed. Think of the
> following analogy.  Run as fast as you can while chasing a car that
> has a rope tied on behind.  Now, after grabbing the end of the rope,
> have the car speed up substantially.  Your running speed won't be
> increased substantially, and you'll soon be fanny over teakettle.
> This leads to the dragging scenario so popular in all the old cowboy
> movies.  It is perhaps more likely that the early wingstroke was used
> more for maneuverability and differential braking. (JRC)<< I should
> add (which I forgot to mention earlier) that in addition to providing
> a strong power stroke, the authors also point out that distally
> located aerodynamic surfaces would enhance the animal's orientation
> control by providing a large turning moment.(PTN)
>
> >>Yes, and can enhance turning ability even without the increase in
> turning moment, by reducing the lateral force that the feet are
> required to resist.(JRC)<<
>
> An animal with this arrangement of wing feathers wouldn't be a very
> efficient glider, however, because of the low lift-drag ratio.(PTN)
>
> >>I tend to disagree with this, since there's nothing about this
> configuration that would make the lift-drag ratio take a substantial
> hit (induced drag would be increased at a given airspeed and
> interference drag would be reduced, resulting in a probable increase
> in optimum airspeed, in order to reduce the induced drag
> contribution), and the high wing loading would also make the animal
> glide at a relatively high airspeed, which would increase the
> territory covered per unit time, which I take as an advantage.
> However, I haven't done any specific calculations to attempt to
> quantify  this scenario.(JRC)<<
>
> >>Jim<<