An you thought flights were too long now

[BobSch]

Solar-powered plane lands after 26-hour flight.

http://news.bbc.co.uk/2/hi/europe/10550430.stm

[LCHIEN]

The reason why this is significant:
It has been the goal of keeping a plane aloft indefinately to serve as a communications relay or such... replacing cell phone towers with ones with larger cell area, satellites, etc. but with technology that can be easily reached for repair and or modification.

Basically if you can keep a plane aloft for one solar cycle (e.g. one day or 24-hours) then you have achieved the goal of capturing at least as much or more energy in a day than it takes to keep the plane aloft and run systems on it. Then you can go another day etc indefinately if you want. Flying about 30,000 feet you don't have to worry about cloud cover and losing a percentage of the sun power to clouds, just the daily night cycle which is predictable.

The Auto-piloted planes can be flown up w/o humans aboard with radio relay (e.g. cell repeaters or satellite-like functions) 24/7 and a spare plane can replace it when needed for repairs or maintenance. They would just circle overhead at 35,000 feet and do their jobs using collected solar energy.

They would have much greater reach than terrestrial towers and cost way less than space launches with capabilities in-between. And unlike space launches, you can service the equipment.

I can see some issues with becoming air traffic hazards and such, but there are some real benefits if they can do this.

there was some work done on this a few years back by NASA, they flew it to 100,000 ft and were hoping to make batteries to keep it flying overnight. google Helios solar plane
for more info.

[jackellis]

I agree that it's significant and it's a remarkable demonstration, but a test around the summer solstice is not conclusive. Now they need to do the same test in late December.

If the locations are known and fixed, air traffic should not be a problem so long as the pilots of passenger aircraft pay attention. As it is, there are tethered balloons all over the place waiting to snare unsuspecting light aircraft pilots like me, but I can't remember hearing about planes flying into the tethers, which can be thousands of feet high.

[LCHIEN]

...
If the locations are known and fixed, air traffic should not be a problem so long as the pilots of passenger aircraft pay attention. As it is, there are tethered balloons all over the place waiting to snare unsuspecting light aircraft pilots like me, but I can't remember hearing about planes flying into the tethers, which can be thousands of feet high.

The flight last week maxed out at 30,000 feet which would be right in the middle of commercial air traffic lanes.

The flight of the Helios with NASA they were flying to 90-100,000 feet there won't be much traffic there. But then they ascend or decend they do so rather leisurely (they do big lazy spirals to go up or down because of limited power and physical strength) so they may present a hazard while transversing the commercial lanes.