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Re: avian flight




David Marjanovic wrote:

> Indeed. And airspeed may become injurious or lethal...

Only if you can't cope with it upon landing (or impact, as the case may
be).

> ; if you don't have a
> library around which has Neues Jahrbuch für Geologie und
Paläontologie, tell
> me, and I'll send you a scan.

I don't, and would appreciate a scan, if there are no copyright issues
that
would be violated by the scan.

> According to the formula Ebel gives, airspeed is directly proportional
to
> the square root of air density...

Inversely proportional to the sq. rt.

> I think Riet_s_chel's reconstruction looks more like the fossils.
> Aerodynamic convention really is that way, but it only makes sense if
the
> wings are continuous with the body, which is doubtful. I hope I can
find the
> ref for the probability of that gap (probably it has been discussed
onlist,
> it was in New Scientist).

I tend to agree with you re the probability of the gap, but don't think
it has
been demonstrated definitively either way.  However, that is simply my
personal
opinion -- I've not done much of a search on the subject.   If  the gap
exists,
Cl will drop across it, but will not go to zero.

> > > but on the other hand it does not take into
> > > account tail area; these two effects more or less cancel each
other
> out.)
> >
> > No -- they don't.
>
> Statement against statement...

True.  I calculated an estimate before making my statement.  You may
wish to do
the same.

> > ??? Steady-state, the Yalden wing would probably be most efficient
at a
> lift  coefficient on the loose order of about 0.9.
>
> That formula is for parachuting, where there is no lift.

The equations I used in the snipped stuff were for a lifting wing.

> Again, I can't decide; maybe I can help with some data?
>
> from Pat Shipman:

I'm familiar with the table and used the same numbers in my
calculations.

> Neither estimate takes the tail into account. What is the effect of
tails to
> total wing loading and lift in modern birds?

It ranges from roughly -30 to +30 percent (note, that's a rough estimate
only -
I didn't calculate the range).

>         *Archaeopteryx* could most probably land on the ground,
probably it
> used running landings not unlike a plane. Some confusion has arisen in
the
> discussions here, I just claim Archie couldn't glide and couldn't land
in a
> tree.

You may well be right about landing in the tree, though it would appear
that he
could have launched from one.  According to my calculations, he should
have been
capable of a decent glide, though I suspect he was more of an active
flapper.
I speculate that archie mostly launched by leaping and landed by
running, though
it would appear that he could have launched by running as well.

> Moving the wings back to the hips doesn't look feasible in Archie...

Why would he want to?

> Too bad we don't have Ebel onlist.

I agree.

Cheers,

Jim