> Since my time has been tight (to finish the software), the kids have
> started project number two -- a UAV quad-copter.

FYI - here's a comment from someone I know whose group built a Quad
copter before they were all the rage. Left hand threads do have their
place - as do wired nuts, tabbed lock washers and more. :

"For xxx, we thought it prudent to cage the rotors, in case the motors
overspeeded.  That was never an issue that I know about, though I
wasn't very involved in the project (I think I would have heard about
an overspeed cato, though).

One thing that didn't occur to anyone was to get left handed threads
for the Jesus nuts of the counter-rotating rotors.  Fortunately that
flight test was tethered, and out on Nate's balcony.  When the nut
departed and the rotor took flight, it bounced off the balcony ceiling
before it did anything else.  That dumped most of its kinetic energy,
and when it sailed out into the apartment complex courtyard, it didn't
get far.  They found it a few minutes later down by the pool.  The
vehicle just thumped back down onto the table when the rotor departed.
 We suspected the software overspeed controller had kicked in on the
departure motor, but with no telemetry, there was no way to be sure."


          R
--=20
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