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Re: Fukui memoirs, pterosaur paper



There is still a third possibility, one that would work well
aerodynamically.  That is a narrow wing with the trailing edge at the
elbow being about 40-50% of the length of the humerus behind the elbow,
then turning aftward inboard of the elbow to connect to the inboard
thigh or shin as a non-structural fuselage fillet intended to reduce the
interference drag at the wing-fuselage interface.  It is possible that
the anterior ankle membrane doesn't always extend all the way to the
hip, so that the knee and inboard part of the shin form a rounded
leading edge for the aerodynamic 'hindlimb/uropatagium/biological tail'
complex.  This can provide for an ankle attachment without a direct
patagium trailing edge path toward the wing tip.  the direct path from
the ankle attachment would be more toward the knee and then the wing
root.  This has several advantages.  It greatly increases the aspect
ratio of both the tail and the wing, it increases the flight speed, it
reduces the amount of power required to maintain level flight (it Q
northropi it reduces required level flight power from roughly about 4hp
down to about 1.25 hp), it facilitates yaw command authority, it
provides an effective supplemental source of pitch command authority in
addition to  wing sweep and wing cusp, it enhances pitch stability, it
greatly reduces tail drag, and during the occasional flapping sequences
the relatively stationary aft surface substantially increases the
efficiency of thrust production by the wing.  It also frees up the front
and rear legs and allows them to articulate with appropriate timing and
kinematics for the launch process. One of the things that intrigues me
about both Q species and Q northropi is that it appears that by the time
the hands leave the ground during launch (and the hands appear to be the
last thing to leave the ground), the animal is already moving faster
than any probable predator would be able to run (or swim).  Everything
that I've seen in Quetz leads me to speculate that the
hindlimb/tail/uropatagium complex was pretty much kinematically
independent of the wing, had about 1/3 the surface area of the wing, and
about half the aspect ratio (about 7 or 8 vs. 16 to 17).  With this
configuration, most of the yaw command authority problems so prevalent
in the standard pterodactyl configuration become insignificant.  As an
aside, insofar as I know, none of the Quetz skeletal sculptures have
been placed in this flight configuration yet.  The TMM cable support
structure was placed before the sculpture arrived, so it couldn't be put
in that orientation and still make the opening deadline.  The Sibbick
illustrations in the June(?), 2001 National Geographic don't reflect
this position either.  In any event, pterosaurs came in enough sizes and
species that there was likely room for substantial variation in the
wing/torso/hindlimb interface.
Jim

Jaime A. Headden wrote:

>   It is my understanding that numerous specimens show the wing articulated
> to the ankle, wether the wings was narrow or deep, but that some
> pterosaurs may have, for aerodynamic purposes, moved the wing to the hip.
> However, at least Dendrorhynchoides and specimens of Rhamphorhynchus show
> the ankle articulation and a large area of skin and hair around this,
> which would go to show the membrane was in fact attached at the leg in
> these forms.