In article Andrew Sarangan writes:

On a clear day, the average solar power incident on the earth's
surface is 1400Wm^2. http://hypertextbook.com/facts/1998/...utbundit.shtml

No, that is the solar power at the top of the atmosphere.

By the time it gets through the atmosphere, the accepted figure is
1000 watts per square meter.

Consumer solar cells are available claiming about 20% efficienty now.
If they can do as their ads claim, the 16 sq meters of the top of the 172
will get 3.2 kW under direct solar radiation, and perhaps 70% of that on a
typical mid-day for most of us due to the sun angle being lower than
directly overhead. That 2.25 kW would give 3 horsepower if the conversion
were 100 percent efficient (it isn't).


As for 100 percent efficient solar cells, you say:

We are already doing it, for specialized applications. Internal
quantum efficiencies of certain semiconductor materials have
approached nearly 100% within a narrow spectral range.The challenge is
how to translate that to match the broad solar spectrum. The know-how
exists, but there isn't enough investment to make it happen.

If you believe that, you should be out convincing investors that you
can make them very rich. Don't tell us. Show us.

Convince those that point out that the laws of thermodynamics
setting limits apply to solar cells too.


Had we spent all the post-911 terrorist-aversion expenditures on
something like this, we could be declaring independence from the
middle east.

Speculation, with no facts in evidence.


I know that we spent several millions erecting a metal fence around
our small GA airport. All it did was screw up the localizer signal and
trap the deer population. I don't think even the administrators
believed there was a terrorism threat here.

Yes, the whole security paranoia over aircraft has not gone away.


On the other hand, NSF (National Science Foundation) budget has barely
kept up with inflation in the past 10 years. This is where we count on
for fundamental break throughs in discovery.

Last I checked, the NSF didn't do research. Universities do some, but
putting things into production is done by businesses.



Now, if I had the cash, I would be inclined to see if that 3 horsepower
could be fed to a reasonably efficient prop to drive an ultralight around.
It might be difficult to stay ultralight with all the solar power weight,
but it would be fun if it could be made to work.


Alan