[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re:


----- Original Message ----- From: "Richard and Jo Cowen" <cowen@blueoakfarm.com>
To: "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Monday, October 24, 2005 1:59 PM


Lately several people have written approvingly of “cruising flight”
for Archaeopteryx. The idea is that once airborne, it would have been
capable of staying up there. HOWEVER, all agree that take-off would
have been difficult, and that landing would have been difficult too.

I don't believe that ALL agree on the latter two things being difficult. For example, it is perhaps possible that Archaeopteryx took off by leaping (to a speed great enough that the supracoracoideus isn't a major player in the wingstroke). I think a running takeoff might be unlikely for Archie -- but a running landing (or even maybe, a walking landing) is highly probable (again, because of the sc alignment, and during landing, because of the very high lift coefficient achievable by the tail).

And, although I approve of Archie's 'ability' to do cruise flight effectively, I sort of doubt that it could do so for really extended durations. I would expect Archie to go for a Strouhal number of roughly about 0.2 to 0.3 when flying, but don't currently have an opinion re how long the beastie could keep it up.

I have driven cars that were only operational in “cruising” mode (see
below). They just don’t work. And neither does a flying Archaeopteryx.

Why not? In aeronautical terms, please. I don't really buy into automotive analogies for takeoff and landing.

The problem with saying that a 'cruise only' wing doesn't work is that it artificially establishes constraints by ignoring potential alternative methods of takeoff and landing that may sidestep many or most of the early wing's shortcomings. Mad flailing isn't necessarily necessary for either landing or takeoff. For example, pterosaurs don't appear to have been capable of much mad flailing, and they took off and landed quite handily for quite a substantial period of time.

All the best,
JimC