Alternate Fuel Vehicles

"John Frazer" wrote:
>> (No, neither the SSPS power beams nor the aircraft beams can
>>be taken over by terrorists or militaries to burn cities. The SSPS
>>beam is less powerful than sunlight in a frequency which can't
>>hurt an airplane or bird, and the airplane power beams can't be
>>focussed at anything below 30,000 feet.)
>
"Xenophile" wrote:
> Good bit of anticipation. This question was bound to be asked. I
>would recommend also that a bit of fuel be kept on board, even
>though that would hurt efficiency. Just in case the beam is cut off
>(military, terrorist, asteroid, debris, etc.).

Add in to the list of difficulties "Software glitches, human error..." the most
likely problems with any such system.

I thought I did say that planes might carry ~20% of the fuel that would be
normal today. Maybe an hour of endurance, in addition to what's needed for
climbing up to / descending from cruise altitude.
The fuel might be pressurised or liquid CH4 or maybe just around liquifaction
temperature, so boil-off is contained as pressurised gas and leads to easy
flow. Maybe some sort of gel or some synthetic which is slightly more
energetic / compact than straight CH4 and more easily carried & handled
than pressurised or liquified gas.

BTW, something relevant
http://www1.msfc.nasa.gov/NEWSROOM/news/releases/2003/03-180.html
10-09-03
NASA research team successfully flies first laser-powered aircraft
...
The laser tracks the aircraft in flight, directing its energy beam at specially
designed photovoltaic cells carried onboard to power the plane's propeller.
...
The plane, with its five-foot wingspan, weighs only 11 ounces and is
constructed from balsa wood, carbon fiber tubing and is covered with Mylar
film... Designed and built at Dryden, the aircraft is a one-of-a-kind, radio-
controlled model airplane. A special panel of photovoltaic cells... is designed
to efficiently convert the energy from the laser wavelength into electricity to
power a small electric motor that spins the propeller.

There's also some good R&D into air breathing laser thermal craft too
http://www.lightcrafttechnologies.com/