"Ken" <tyl### [at] pacbellnet> wrote in message
news:3EABF9FA.A1437E17@pacbell.net...


> Yeah, but will it fly?  ;~}


It's hard to say. Artie and his company think it will. I'm not an
aeronautics engineer, but I have checked that the lifting surface area is in
the ballpark for a high performance soar plane, even with the added weight
of the electric self-launcher and the extra drag of the wing tip risers.
When the prop is fully feathered, its drag is supposed to be negligible. The
main thing now is whether they can get the control software right. The
design has no "inherent aerodynamic stability", which means that it is
completely dependent on its sensors and software to self-correct. A totally
fly-by-wire system. If its computers die, it would fly no better than a...
hmmm. Than a dead duck.

The weight is misleading. The 155 lb is its "bare" weight-- stripped of the
prop, motor, flywheel batteries, redundant computer modules, and everything
else they can pull out of it. To meet USA FAA qualifications as a "non
powered ultralight vehicle", the bare weight has to be kept below 155 lb.
But the FAA does exclude the emergency parachute system and some other
safety features in its weight allowances. Anyway, its normal "ready to fly"
weight is probably around 260 - 275 lb, so with a pilot it would still be
less than 500 lb. That's supported by a total wingspan of 54 feet and
lifting surface area of about 142 sq ft, with an aspect ratio that is better
than the soar planes that have been breaking the world records the last
couple of years.

I do think Artie and his group are kind of skirting the edges when they call
this a non-powered vehicle, but what do I know? They say they are on firm
legal ground. Maybe so-- the flywheels only store about half an hour of full
power.

You can see five of the bird's major sensors in this image. The venturi
tubes outboard of the upper wing detect small variations in air pressure
during maneuvers as well as having something to do with trimming the wings'
camber. The cameras in the chin turret can track the horizon during banks
and turns. That's augmented by the wing mounted cameras (which don't show up
well in this image: they are the round things on the top wing toward the
wingtips.) There are also barosensors on the wings and body, and
microphones, too. Artie talks of it being able to listen to the wind and
adjust itself accordingly.

Well, maybe it will fly. I think it all depends on whether they can grow the
right neural nets in the software. It's strange-- there are about four guys
who made a fortune in the boom days of Silicon Valley who are all chasing
after that rocket prize: first private citizens in space and all that. And
here's Artie and his group chasing after a dream of slow afternoon flights
riding the thermals. I guess we need both kinds of dreamers, huh?


--
Will Woodhull
Thornhenge, SW Oregon, USA
willl.at.thornhenge.net

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