Larry Dighera wrote in
:

If I recall correctly, the article mentioned the wings being clad in
photovoltaic solar arrays, so if the aircraft were tied-down outside,
conceivably it might recharge its internal battery pack without
purchasing utility power.

Some more back-of-the-envelope calculations, disgregarding losses
and efficiency concerns.

Maximum insolation on the Earth's surface is about 1kW per square
meter.

According to wikipedia, a Cessna 172's wing area is 16.2 square meters.

According to a graph on the wikipedia article on solar cell efficiency
the most efficient cell ever developed is 44.7%.

http://en.wikipedia.org/wiki/Solar_cell_efficiency

OK...

16.2 square meters times 1kW per square meter is 16.2 kilowatts.
Multiplied by 44.7% leaves 7.2414 kilowatts.

Even if you had 10 hours of ideal sunlight, you'd only get a
total of 72 kilowatt/hours of energy.

From my previous post of the Cessna 172's engine putting out 120kW
of power, 10 hours of charging would only get you 36 minutes of
flight. Lower power settings of course extends that, but recall I'm
neglecting all the forms of losses.

Don't get me wrong. I'm not saying the venture is not a good idea
and I'm not trying to knock it down. But there's reality and then
there's marketting hype.

As Scotty was fond of sayin', "Ye canna break the laws of physics,
Cap'n!"

Brian
--
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