Re: The origin of flight: from the water up (still short!)

["David Marjanovic" <david.marjanovic@gmx.at>]

----- Original Message -----
From: "James R. Cunningham" <jrccea@bellsouth.net>
Sent: Wednesday, March 27, 2002 7:05 PM


> > When the wings are below a certain relative size, flight is impossible.
>
> Doesn't that depend to some extent on the airspeed?  And size relative to
what?

I am just being difficult when I respond that Superman's area (including his
cape) is enough to keep him in the air once he has reached something over
200 km/h, no? :o) The wings of birds generate both lift and thrust, so which
airspeed can be reached with what amount of force depends on the wing area
and shape.
        Size relative to... probably total weight?

> > *Rahonavis* has longer wings [...]
>
> Interesting.  In Quetzalcoatlus, the relative ulna length decreases as
wingspan
> increases.

Because Big Q has a few more elements that can grow, such as the wing
finger, I assume.

> >     - If the tail with its long rectrices was used for steering in
Archie,
> > it would have been rather difficult to move if it would have been
longer.
>
> I rather doubt that it's primary purpose was for steering, but it probably
could
> have been used for that too.  Why would it have been more difficult to
move if
> it were longer?  I presume you are talking about moving while in flight?

Oh, sorry, I'm talking about moving underwater. When the tail is too long
there, it requires excessive power to be moved (except in the plane of the
rectrices).

> > (I can suggest a probably cheap way to do it: Take a cormorant, [...]
>
> Doesn't this presume that Archie had near zero control over tail mobility?

I don't think so. I'm just suggesting a possible test, cheaper than a wind
channel, for how having an Archie tail influences manoeuverability in water.
:-)