To All:

Kelly Borsum also suggested that I use a more appropriate subject
listing for this post -- formerly 'Piezo Gyros, etc'.  For those of you
who read the earlier, virtually identical post, sorry for the repeat.
But not sorry enough not to repeat it.

For a couple of years now, working with a friend at UT Austin, I've been

researching the flight and biomechanics of two large, late-Cretaceous
azhdarchid pterodactyls, Quetzalcoatlus species and Quetzalcoatlus
northropi (northropi is the animal that Paul MacCready of Aerovironment,

Inc. replicated in half scale a few years back  -- you may have seen his

replica on the Discovery Channel).  For the last year or so, Paul has
been
encouraging me to build another flying replica to incorporate what we've

learned about the animal's flight mechanics since he constructed
his model, particularly since yaw authority is no longer a major problem

(although stability remains an issue).  Should I do so, I will probably
go for a full scale replica of species at a 16 foot span rather than a
half scale of northropi at an 18 foot span, and my wing articulation
will be somewhat different from Paul's. The legs and uropatagium would
be used to approximately replicate their actual control functions rather

than held retracted like Paul's original replica.

My background is in fluid mechanics, and I have no experience with RC
models though I am a pilot and involved in drag reduction mods for
general aviation and air racing.  If I construct another flapping
replica, it
will require gyro stabilization on all three axes, and I'm thinking of
using Murata ENC-03J's, together with an on-board computer to merge PCM
signals from the receiver with the processed output from the gyros and
computer to operate Astroflight motors and ball-screw drives.  I have no

experience in that either.

My question to any of you (if you have time to respond) is, do you
recommend PCM as the best choice for this application?  Can you
recommend any good primers on the specifics of PCM control?  And,
unofficially, do you have any recommendations about brand names for
radios,  receivers, update rates, etc.?  The short period pitch
oscillation on my replica would be on the loose order of 0.1 second, and

I'd probably need an update from my pitch rate gyro 4 to 5 times during
that period, but can get away with a somewhat slower update rate on the
other axes.

Though they were effective at flapping flight for short durations, the
animals
were primarily sailplanes, both stately and fast.  In a
standard rate turn with airspeed set for best L/D (glide ratio), the
diameter of their turning circle was about 2500 feet, so they'd have
trouble staying close to a ground station.  Even in a one minute turn,
they'd eat up a quarter mile turning around.

Any comments or thoughts of your choosing would be welcome.

Thanks for your time,

Jim Cunningham
Cunningham Engineering Assoc.
578 Whittenburg Drive
Collierville, TN 38017
Ph 901-853-8377
e-mail jrccea@bellsouth.net