Richard Riley wrote:
On Sun, 14 Jan 2007 04:27:40 GMT, wrote:
If you covered the entire surface of the envelope with solar cells,
you'd need to _average_ 0.172 kW / m^2 to get that much power. If
you assume that everything is great and you're getting 1 kW / m^2
coming in, that's 17.2% efficiency.

Total solar flux of 1 kw/m2 assumes noon on a clear day at the
equator.

That's part of what I meant, but didn't make explicit, when I said
"everything is great".

Average flux in North America throughout the year is between
125 and 375 w/m2 depending on where exactly you are.

I found those same numbers at http://en.wikipedia.org/wiki/Solar_power ,
which cites http://www.nrel.gov/gis/solar.html . But that apparently
also includes night and cloudy days, so what's actually coming in on a
sunny day will be more than that. I agree that it won't get all the way
up to 1 kW / m^2. Since the proposed blimp will apparently be day VFR
only, using the higher daytime insolation should be OK. What happens
when clouds blow in or you stay out too late is left as an exercise for
the student.

Matt Roberds