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Re: WING FEATHER ATTACHMENT




Michael Bruce Habib wrote:

> Again, I have caused confusion.  My apologies...

No need.... I confuse easily.  The reason that I asked, is that I've noticed 
that some jargon
terms have different meanings in aerodynamics than they do in biology or 
paleontology, so I
think terminology warrants clarification across the specialties.  Verbal 
communications are
extraordinarily difficult under the best of circumstances.

> > This seems to presume that the force production is primarily from drag 
> > rather than from
> > imparting a downward component to the velocity vector of the freestream 
> > passing across
> > the wing.
>
> Yes,.......  I was making this
> assumption because I did not believe we were assuming the
> animal had a full wing, or advanced wing elements, which I
> assumed (perhaps erroneously) would be needed to produce a
> stable freestream across the wing.

Even a flat plank will fly quite well, up to a lift coefficient of about 0.9.  
Most evolved
flyers cruise at a CL of about 0.9, give or take.  The plank and the cambered 
wing also have
about the same lift slope.  The big difference is their angle of attack at zero 
lift.  The
evolved flyer will glide with the chord about parallel to the free stream, 
while the plank
chord will have an incidence of about 8 or 9 degrees (exclusive of induced aoa).

> Yes, and modern birds and bats have full wings, with
> powerful flight muscles to work them.  The original
> assumption involved an animal with distal wing components
> only.

These aftward forces aren't necessarily all that large (though the moments 
produced may be).
Q northropi has about 6 to 8 pounds of drag shoving back on each wing during 
cruise flight.
Small animals have a lot less force, but the force taken as a percentage of 
body weight will
be much greater with lower glide ratios. I don't mean to imply that it is easy 
for them.

> , they have
> the ability to control themselves much more while aloft
> than the mostly landbound animal I was imagining with the
> distally feathered arms.

I suspect that my unfocused mental image of the purpose of a distally feathered 
wing would be
to increase maneuverability, so control could be expected to evolve in time to 
keep up with
flight ability.  Again, note that I do not necessarily buy into this scenario, 
I only point
out that it could be made to work.

> These birds also have a very
> different wing type from the primitive glider originally
> assumed.  Basically, the flight apparatus on a soaring bird
> and a gliding theropod or basal bird seem very different in
> my mind.  The aspect ratios are completely different for
> one.

Sure, but that just means that they can be expected to fill different niches.  
Which they do,
or did.