Solar Craft Flies Through Two Nights

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Solar Craft Flies Through Two Nights

Posted by ScuttleMonkey on Monday September 10, 2007 @08:43AM from the nasa-awash-with-envy dept.

An anonymous reader writes "A solar-powered, unmanned craft has flown for 54 hours — a record for both unmanned aerial vehicles and solar craft. None before has managed to store enough solar energy to fly through more than one night. There is also a video showing the 18m carbon fiber wing craft being launched."

156 comments

An idea by Anonymous Coward · 2007-09-10 08:44 · Score: 1

Couldn't a solar craft just follow the sun around the earth, indefinitely?
1. Re:An idea by corsec67 · 2007-09-10 08:46 · Score: 1
  
  At a high enough altitude, sure.....
  
  --
  If I have nothing to hide, don't search me
2. Re:An idea by dartboard · 2007-09-10 08:47 · Score: 3, Informative
  
  Sure if it could go 1000 mph, that would work fine. It might be tricky to break the sound barrier with a solar-powered craft though.
3. Re:An idea by Manhigh · 2007-09-10 08:48 · Score: 3, Informative
  
  Sure, if it's fast enough. Solar powered aircraft tend to be driven by large, slow-turning propellers. Even commercial jet aircraft typically can't beat the Sun from the eastern US to the west, so I doubt we'll be seeing such a solar powered aircraft anytime soon.
  
  --
  "Open the pod by doors, Hal" > "I'm afraid I can't do that, Dave" sudo "Open the pod bay doors, Hal" > alright
4. Re:An idea by stoolpigeon · 2007-09-10 08:48 · Score: 1
  
  they probably can't go that fast. then there is weather, wind, what not.
  
  --
  It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
5. Re:An idea by caramelcarrot · 2007-09-10 08:50 · Score: 1
  
  It'd have to be flying at supersonic speeds to follow the sun, and that thing certainly isn't flying at supersonic speeds. As you go faster, you're wasting more energy on air resistance, at which point it'd be even less feasible to use solar power.
6. Re:An idea by SatanicPuppy · 2007-09-10 08:54 · Score: 2, Informative
  
  Wind sure, but not weather. The thing cruised at 18,000 meters, solidly in the Stratosphere; not much up there but ozone. Even the wind wouldn't be that big a deal; the stratosphere is so called because it sits in layers (strata), and as long as you're not climbing or descending, your environment should stay pretty much the same.
  
  --
  ad logicam Claiming a proposition is false because it was presented as the conclusion of a fallacious argument.
7. Re:An idea by everphilski · 2007-09-10 09:02 · Score: 4, Interesting
  
  Depending on the time of year it wouldn't have to do that... you could have it do loops around the north or south pole at a much higher latitude and still get sunshine 24/7 (or damn near close) and not have to travel as fast as they would near the equator to keep up with the sun.
8. Re:An idea by 91degrees · 2007-09-10 09:02 · Score: 1
  
  Or how about just heading north a bit and going at half that speed. Or even better go a bit further than that during mid summer and then it makes no difference how fast you go because you'll be in 24 hour sunlight.
9. Re:An idea by Spy+der+Mann · 2007-09-10 09:03 · Score: 1
  
  Couldn't a solar craft just follow the sun around the earth, indefinitely?
  
  Until the next solar eclipse, that is. :)
10. Re:An idea by Anonymous Coward · 2007-09-10 09:12 · Score: 1
  
  It'd have to be supersonic?
  
  Ground speed of the Sun is roughly 40,000/24 * cos(latitude) km/h.
  Speed of sound = 1225 km/h.
  
  Solving, the ground speed of the Sun is supersonic only between roughly 43 degrees N and 43 degrees S.
11. Re:An idea by dougmc · 2007-09-10 09:22 · Score: 4, Informative
  
  Or even better go a bit further than that during mid summer and then it makes no difference how fast you go because you'll be in 24 hour sunlight.
  The problem with that idea is that as your latitude goes up, the angle of the sun goes down. It approaches 90 degrees at the equator, but it's much lower above the arctic circle. So solar cells on top of your plane will be *much* less efficient. You might be able to make a second giant `wing' of solar cells that you can adjust the angle of (but it generates no lift, so you still need your main wing), so it's nearly vertical to catch that sun at midnight above the arctic circle, but in that case you've greatly increased the weight and drag of the plane, and even then the sun you're picking up is greatly reduced in intensity because it's gone through lots and lots of atmosphere.
  
  Storing energy is the key. You might be able to store it in batteries like these people have done, or store it in your altitude and just let it glide down at night -- but that would require a really efficient plane. This looks to be a really efficient plane, but it's obviously not quite efficient enough to do that.
  That would be cool if they'd try to fly it across the Atlantic -- it would be the first electric plane to do so, and the first solar powered plane to do so. TAM 5 took 39 hours to cross the Atlantic, and this plane was up longer than that -- but it's a lot slower too. TAM 5 averaged about 48 mph, and I'll bet this plane is less than half that.
12. Re:An idea by LWATCDR · 2007-09-10 09:23 · Score: 3, Informative
  
  There are some problems with that idea.
  That would work only in the summer.
  That would be handy only if you needed that aircraft over the polar region during the summer months.
  Then you have the really big problem...
  The solar panels are mounted on the wings... The sun at the poles never climbs very high in the sky so the panels would have to be mounted on the sides of the aircraft. That would limit your collecting area a lot and or produce a lot of drag.
  
  So the idea while interesting at first glance really is far from practical.
  
  --
  See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
13. Re:An idea by Gadgetfreak · 2007-09-10 09:26 · Score: 2, Informative
  
  In case you don't want to do the rough math, the Earth is a little less than 25,000 miles around at the equator. So you'd have to go about 1040 MPH to maintain your position with the sun. Less if you're away from the equator, but still way faster than solar craft are flying now.
  
  --
  "No fair, you changed the outcome by measuring it!" - Professor Hubert J. Farnsworth
14. Re:An idea by Anonymous Coward · 2007-09-10 09:31 · Score: 0
  
  Erm... this depends on your latitude... I can walk west around the north pole faster than the sun...
15. Re:An idea by Anonymous Coward · 2007-09-10 09:32 · Score: 0
  
  Envelope math is fun.
  
  The sun moves at 360 degrees per 24 hours relative to the earth. A plane would have to match that. Assuming an average altitude of 10 kilometers and an estimated earth radius of 6365 km, that's a circumference of about 40,000 km (hey, not very different at the equator). 40000 km / 24 hours is 1667 km per hour. That's like mach 1.3 constantly.
16. Re:An idea by Anonymous Coward · 2007-09-10 09:39 · Score: 0
  
  In case you don't want to do the rough math, the Earth is a little less than 25,000 miles around at the equator. So you'd have to go about 1040 MPH to maintain your position with the sun. Less if you're away from the equator, but still way faster than solar craft are flying now.
  
  Far enough from the equator I can walk faster than the sun moves. Since many long flights tend to cross the arctic, I'm not being silly. Someone I know on a recent China->US flight traveled faster than daylight.
17. Re:An idea by Anonymous Coward · 2007-09-10 09:40 · Score: 0
  
  While as a practical matter, the idea is without merit (especially if you want to fly at arbitrary geographic points), but if you were close to one of the poles...
  
  Due to the seasonal tilt of the Earth's poles, it wouldn't exactly be at the poles, but it's be somewhere in the arctic circles. Given that you'd be flying at a high altitude as well, I don't think it's at all implausible that you could find a point where a solar powered craft could stay illuminated indefinitely, with a minimal velocity.
  
  Of course, during the midnight sun periods of the year, it should be quite trivial. :)
18. Re:An idea by Anonymous Coward · 2007-09-10 09:42 · Score: 0
  
  Oops, I meant not very different than the circumference at the ground at the equator.
19. Re:An idea by flyingsquid · 2007-09-10 09:58 · Score: 3, Funny
  
  So the idea while interesting at first glance really is far from practical.
  I have an idea- how about mounting some LEDs on the wings which could help boost the amount of light the solar panels recieve? You could keep going for like, forever.
20. Re:An idea by Daedone · 2007-09-10 10:19 · Score: 3, Informative
  
  Lisa, in this house we OBEY the laws of thermodynamics!
21. Re:An idea by rleibman · 2007-09-10 10:34 · Score: 2, Interesting
  
  Speed of sound = 1225 km/h.
  
  I am going to be pedantic and point out that the speed you give is at sea level, looking this up in wikipedia I read that the speed of sound in air is not heavily dependent on air pressure but more on temperature (it is slower as you go up since it gets colder).
  
  At 29,000 the speed of sound is merely 1083 km/h.
22. Re:An idea by Toutatis · 2007-09-10 10:58 · Score: 1
  
  Don't make it so hard. Try it near a pole (on summer).
  
  It won't be indefinitely, but maybe you could go around the globe several times.
23. Re:An idea by Cassius+Corodes · 2007-09-10 11:07 · Score: 1
  
  Already patented - Along with fans that blow air into wind power plants.
  
  --
  Control is an illusion, order our comforting lie. From chaos, through chaos, into chaos we fly
24. Re:An idea by stevenvi · 2007-09-10 11:29 · Score: 0, Troll
  
  Actually, according to Wikipedia, the equatorial circumference of the earth is 40,075.02 km. So the plane would have to be traveling at 1669.7925 km/hr to keep pace with the sun.
  
  What? Imperial units you want? Fine. 1 kilometer = 0.621371192 mi according to Google, so the plane would have to travel at 1037.56095611766 miles per hour. So the other poster who said 1000 was actually quite close.
25. Re:An idea by CastrTroy · 2007-09-10 11:32 · Score: 1
  
  But because you would have perpetual sunlight, you wouldn't have to carry batteries that needed to hold a charge (or would need considerably fewer batteries). Judging by the weight of most batteries I've seen, this could cut the weight considerably.
  
  --
  
  Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
26. Re:An idea by CastrTroy · 2007-09-10 11:43 · Score: 1
  
  Just as a reference point, the Concorde has a cruising speed of 1350 mph. However I'm wondering if we have to change the distance around the earth, since the circumference is measured from the surface of the earth, Actually, never mind, just checked, if you assume flying at an altitude of 30,000 ft (5.68 miles), then you only increase the distance around the earth by about 100 miles. So, if the Concorde can beat the sun around the earth, can it go back in time? Isn't that how superman did it?
  
  --
  
  Anthropic principle: We see the universe the way it is because if it were different we would not be here to see it.
27. Re:An idea by dougmc · 2007-09-10 11:48 · Score: 1
  
  Yes, but it's perpetual crappy sunlight. Above the arctic circle, the sun never gets very high above the horizon, especially at night. And so it may go through many hundreds of miles of atmosphere, which makes it weaker -- compared to the dozens of miles it goes through near the equator -- and most of the atmosphere is hit in the last six or so miles.
  
  And also the plane would have to fly at approximately right angles to the sun -- if not, the solar panels would be at an angle, and power would drop even more. (You couldn't make the solar panels able to rotate in that direction, because then they'd create massive amounts of drag and the plane would not fly.)
  It might be possible to make a plane that takes advantage of the 24/7 sunlight to stay up 24/7 without large batteries, but it wouldn't be as easy as taking this plane and flying it up north. You'd have to design your plane totally differently, and it probably wouldn't be any easier than designing this plane was.
28. Re:An idea by msevior · 2007-09-10 13:13 · Score: 1
  
  Well for 6 months at least if was at the North or South Pole :-) I guess sit would have to work out some tricky aerodynamics to keep the solar cells facing the sun though.
29. Re:An idea by ChrisA90278 · 2007-09-10 13:27 · Score: 1
  
  "Couldn't a solar craft just follow the sun around the earth, indefinitely?"
  
  Have you done the math? How big is the Earth? It would have to fly all
  the way around once every 24 hours. It works out to just over 1000 miles
  per hour. Millitary jet fighters can do this speed for short sprints but you
  can't really do that with an electric driven propeller.
30. Re:An idea by beckerist · 2007-09-10 13:35 · Score: 1
  
  I didn't do the math, so this is more a question than a statement:
  
  A + B = C + D
  A hours good sunlight + B hours crappy sunlight < C hours good sunlight + D hours NO sunlight ?
  
  personally, and I'm no aviation expert, but I'd think that if you made (and executed) an efficient flight plan, I don't see why this wouldn't work!
31. Re:An idea by stoolpigeon · 2007-09-10 13:56 · Score: 1
  
  Thunderstorms can get taller than that - and I'd imagine even if one were a bit lower, the disturbance would extend above.
  
  --
  It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
32. Re:An idea by DieByWire · 2007-09-10 14:49 · Score: 1
  
  I didn't do the math, so this is more a question than a statement:
  
  A + B = C + D
  
  A hours good sunlight + B hours crappy sunlight < C hours good sunlight + D hours NO sunlight ?
  
  The reason is doesn't work is that rate climb is a function of excess power. (i.e., power in excess of what's required for level flight.)
  
  Let's say an electric aircraft (powered glider, really) requires 10 watts for level flight. If it gets 9 watts for 24 hours, it will never have enough power to sustain level flight. Launch it, it lands.
  
  Give it 18 watts for 12 hours, and it will climb for 12 hours. (The rate of climb will depend on the weight of the aircraft - just turn 9 watt-hours into poetntial energy to get the theoretical max altitude gain .) After that, it will glide for, say, 9.6 hours.
  
  Of course, these are contrived numbers, but they illustrate the point - you need excess power to climb. So a little high power time will beat a lot of weak power time.
  
  --
  Never shake hands with a man you meet in a fertility clinic.
33. Re:An idea by DieByWire · 2007-09-10 14:53 · Score: 1
  
  ...just turn 9 watt-hours..
  D'oh! 18 - 10 = 8 in most places. Make that 8 watt-hours.
  
  --
  Never shake hands with a man you meet in a fertility clinic.
34. Re:An idea by fractoid · 2007-09-10 15:21 · Score: 1
  
  Faster than daylight is quite a trick. ;) Good point about the latitude, at 45 degrees you only have to travel about 0.7 times as fast to keep up with sunlight. Also, remember that when a plane is taking off, the altitude gain can cause the sun to re-rise even if the forward motion of the plane would be too slow to produce such an effect on its own.
  
  --
  Rampant carbon sequestration destroyed the Dinosaurs' tropical paradise. I'm here to help repair the damage.
35. Re:An idea by dougmc · 2007-09-10 15:25 · Score: 1
  
  One problem is that above the arctic circle, it's more A hours crappy sunlight (during the `day') + ( 24 - A ) hours *really* crappy sunlight (during the `night'), thanks to the sun being so low on the horizon, even at high noon -- even if you do have the fancy second rotatable wing with all the solar cells on it so they can always face the sun as much as possible, while the main wing is always level (unless turning, of course, but when you want efficiency, you turn as little as is possible.)
  
  Now, what might work would be going back to the normal `solar cells on the wing' method during the day, and rely on thermal or slope lift to keep you going during the night (but that might be seen as cheating.) Thermals usually peter out at night, but you might be able to find something that stays hot all the time -- like a nuclear plant, or perhaps it's cooling lake. And as for slope lift, wind often reverses direction at night around the coast, so it might be hit or miss, but the right slope would still work. That, and I'd hate to fly a plane that was obviously so hard and expensive to build so close to the ground, close to a slope ...
  The R/C slope (no motor at all!) world record is 36 hours. Good conditions, some modest solar panels (to recharge the RX and servos during the day), the right slope and plane and lots of planning could probably beat this record. If you decide that using slope lift is OK for your solar powered electric plane longevity flight, you could keep it going going for a very long time -- use the motor during the day once your batteries are charged, and at night use the slope lift, only using the motor if you get into trouble.
36. Re:An idea by Anonymous Coward · 2007-09-10 15:49 · Score: 0
  
  well, then I appreciate you repeating it for us
37. Re:An idea by gomoX · 2007-09-10 17:29 · Score: 1
  
  You don't get any power from the sun at high latitudes. It's not just about the sun being there, it's also about the angle of incidence its rays have.
  
  --
  My english is sow-sow. Sowhat?
38. Re:An idea by Rockin'Robert · 2007-09-10 18:37 · Score: 0
  
  NO. A one foot square panel directly facing the sun at the equator and at the poles will still receive the same amount of solar radiation (except for energy loss due to atmospheric: density, pollution, moisuure etc).
  
  RR
39. Re:An idea by salec · 2007-09-10 22:37 · Score: 1
  
  But, planes control their roll. Couldn't a plane be flown in horizontal flight, keeping direction, tilted toward one side?
40. Re:An idea by isorox · 2007-09-10 22:38 · Score: 1
  
  It might be tricky to break the sound barrier with a solar-powered craft though.
  
  Good aerodynamics, lots of altitude, aim down.
41. Re:An idea by Eivind · 2007-09-11 01:31 · Score: 1
  
  It depends though, the closer you are to a pole, the shorter a distance you need to fly to go troug all time-zones.
  
  I wonder if anyone has been flying for like a week in northern latitudes during midnight-sun. It should help a lot to have 24 hours of sunshine, but the problem is that sunshine comes in almost horisontally, so it's a lot harder to make use of it if your solar-cells are mounted ontop of the wings as is customary.
42. Re:An idea by Anonymous Coward · 2007-09-11 03:36 · Score: 0
  
  Not Really. Angled sunlight means that a ray of sunlight has to go through much more of the earth's atmosphere, meaning much energy is lost in the process. It's why you can look at a sunset without needing protective glasses, but can't do so at noon.
43. Re:An idea by Anonymous Coward · 2007-09-11 03:48 · Score: 0
  
  "A one foot square panel directly facing the sun at the equator and at the poles will still receive the same amount of solar radiation (except for energy loss due to atmospheric: density, pollution, moisuure etc). "
  
  I think you forgot that atmospheric losses are tremendously higher at the poles than at the equator, due to the low angle of sunlight (much more atmosphere to go through). Basic trigonometry.
  
  In space, you'd be correct though.
44. Re:An idea by dougmc · 2007-09-11 09:54 · Score: 1
  
  In space, you'd be correct though. If you could get the plane up to 50+K feet, that might be close enough to space to make it work, and yet close enough to Earth to have some atmosphere to fly in? Perhaps aerotowing with another plane could get it up to altitude, then let the solar panels and motors take over, as they'd produce more power up there?
  
  Helios came pretty close to 100K feet. Our `Polar flyer' would be a lot less efficient, as the solar cells would have to be on a second, rotatable by almost 90 degrees, wing, adding lift and drag, and you'd have to always fly at approximately right angles to the sun, but if your goal was to make a plane that could stay aloft for many days, and didn't care that it only worked in certain places, it might be doable.
  But as mentioned, down closer to the Earth, the atmospheric losses would be a killer up near the poles.
45. Re:An idea by CopaceticOpus · 2007-09-13 02:54 · Score: 1
  
  Keeping up with the sun isn't feasible, but it is possible to squeeze more hours of daylight out of every day. Just follow the sun until you lose it, then turn 180 degrees and go catch it coming the other way.
  
  Say that by flying in circles you would experience a 24 hour clock with 12 hours of daylight. By chasing the sun you might get something like a 28 hour clock with 18 hours of daylight.
What the...? by Pojut · 2007-09-10 08:46 · Score: 0, Offtopic

engouh

What the hell kind of spelling mistake is that? Come on editors, at least READ the summary...

--
Living With a Nerd
1. Re:What the...? by Anonymous Coward · 2007-09-10 08:49 · Score: 0
  
  Sho 'Nuff!
2. Re:What the...? by ch-chuck · 2007-09-10 08:52 · Score: 1
  
  Hmm, looks like a word from the Klingon:
  
  Dah, engouh mojaqmeyvam divusnisbe
  
  --
  try { do() || do_not(); } catch (JediException err) { yoda(err); }
3. Re:What the...? by Chapter80 · 2007-09-10 08:53 · Score: 2, Funny
  
  engouh
  What the hell kind of spelling mistake is that? Come on editors, at least READ the summary...
  
  I read it as "enough". Then again, I read this article earlier.
4. Re:What the...? by Gertlex · 2007-09-10 08:54 · Score: 4, Funny
  
  engouh
  
  What the hell kind of spelling mistake is that? A typo?
more by stoolpigeon · 2007-09-10 08:46 · Score: 4, Interesting

This BBC article has good info.

It should not be a surprise that the Global Hawk record did not stand. Look at the two craft. If a global hawk hit the zephyr it probably wouldn't even notice.

--
It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
1. Re:more by Anonymous Coward · 2007-09-10 12:15 · Score: 0
  
  There are many R/C craft that have flown for MUCH more than 30 hours.
2. Re:more by stoolpigeon · 2007-09-10 15:10 · Score: 1
  
  global hawk is a lot more than an r/c. my understanding is that when it made the 20 hour or so flight to Australia - it did so without direct input once it left the ground.
  
  --
  It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
3. Re:more by DustyShadow · 2007-09-10 17:55 · Score: 1
  
  You are correct. It is fully autonomous, from take off to landing. Pilots can give it waypoints but don't actually fly it to those points. It does it all on its own.
Solar powered aircraft are effectively useless by Anonymous Coward · 2007-09-10 08:48 · Score: 0

nt
What good is it? by Anonymous Coward · 2007-09-10 08:48 · Score: 0

A craft that can fly for 54 hours with no payload? Can this thing seriously carry any cargo that is worthwhile? Sounds like an overpriced homing pigeon to me.
1. Re:What good is it? by stoolpigeon · 2007-09-10 08:50 · Score: 4, Insightful
  
  it's good for learning things to be used in later vehicles that will accomplish, you know, stuff
  
  --
  It's hard to believe that's how Micronians are made. Why don't we see it right now by having you both kiss one another?
2. Re:What good is it? by Amouth · 2007-09-10 08:53 · Score: 1, Flamebait
  
  it is called a step in the right direction....... if you cant' see that then please open your eyes
  
  --
  '...if only "Jumping to a Conclusion" was an event in the Olympics.'
3. Re:What good is it? by Anonymous Coward · 2007-09-10 09:04 · Score: 0
  
  They are cheap comm satellites. You fly them up and then they autopilot around for best coverage. Then when they break or wear out you land them and fix the components.
4. Re:What good is it? by Dunbal · 2007-09-10 09:18 · Score: 3, Funny
  
  Can this thing seriously carry any cargo that is worthwhile?
  
  Well if you're in the used battery business, this thing is a gold mine!
  
  --
  Seven puppies were harmed during the making of this post.
5. Re:What good is it? by Anonymous Coward · 2007-09-10 10:29 · Score: 0
  
  Actually, that might be an interesting idea... Various species of migratory birds are still able to easily beat the Zephyr or Global hawk in continuous flight endurance. All that's needed is to fatten 'em up on seeds, vegetation, insects, or fish depending on species and the flying for a week or two comes naturally. Now if you could make a payload small enough to be carried by a bird that could provide a useful service along the migratory path, then you just might have something.
6. Re:What good is it? by forkazoo · 2007-09-10 10:34 · Score: 1
  
  it is called a step in the right direction....... if you cant' see that then please open your eyes
  
  He can't open his eyes right now -- too much solar energy.
7. Re:What good is it? by Daedone · 2007-09-10 12:58 · Score: 1
  
  Yes, but how are we going to get the swallow to carry the coconut?
  I mean, have you ever tried to teach a bird about the buddy system?
8. Re:What good is it? by isaac · 2007-09-10 14:08 · Score: 1
  
  Surveillance package. It's gonna be made by Rockwell, for Rockwell.
  
  --
  I am not a lawyer, and this is not legal advice. For Entertainment Purposes Only.
9. Re:What good is it? by jokitomo · 2007-09-10 16:11 · Score: 1
  
  ... Can this thing seriously carry any cargo that is worthwhile? A coconut perhaps?
10. Re:What good is it? by kimvette · 2007-09-10 17:13 · Score: 1
  
  Yes, but how are we going to get the swallow to carry the coconut?
  
  It could grasp it by the husk?
  
  --
  The Christian Right is Neither (Christian nor right). See: Matthew 23, Matthew 25, Ezekiel 16:48-50
11. Re:What good is it? by Anonymous Coward · 2007-09-10 23:36 · Score: 0
  
  I think that you would need two of these crafts to lift a coconut.
12. Re:What good is it? by TheRaven64 · 2007-09-11 01:45 · Score: 1
  
  Wireless access points. Even at LEO, satellites add latency (not to mention a great deal of expense) to connections. Something like this could be used over rural communities to provide wireless access without satellite latencies. If it can stay up more or less indefinitely, then it can relay signals to an exchange somewhere. Fitting them with point-to-point communications lasers could allow them to be deployed in a mesh configuration, which might be a lot cheaper than deploying cell phone towers in a lot of places, especially if they can be mass produced.
  
  --
  I am TheRaven on Soylent News
13. Re:What good is it? by Anonymous Coward · 2007-09-11 02:34 · Score: 0
  
  What is the advantage here over airships (i.e. blimps) as an access point?
  
  Airships can stay up almost indefinitely, carry fairly large (by weight) or very large
  (by surface area or volume) payloads, can tether (or not, as you wish), and have
  small takeoff / landing areas.
  
  The big problem with airships is altitude limitations, where an ultra-long range UAV
  would have an distinct advantage. It's not clear at all for different applications
  what the correct height would be.
engouh solar energy by InvisblePinkUnicorn · 2007-09-10 08:49 · Score: 4, Funny

From Wikipedia:

"Engouh Solar Energy (ESE) is a newly-discovered form of solar energy capable of lighting even the darkest parents' basement to the point where the average nerd can neither see his keyboard nor the inevitable typos he'll make on internet discussion boards."
Just one question... by Anonymous Coward · 2007-09-10 08:52 · Score: 1, Funny

If this thing requires 3 people running while carrying it to launch, how the hell does it land without breaking? Those same 3 people have to run up behind it and catch it??? Ouch!
1. Re:Just one question... by Anonymous Coward · 2007-09-10 09:09 · Score: 0
  
  Uhh. . .launch is usually a lot trickier than landing, simply because launching/takeoff requires a large energy input, while a landing requires none.
  Was this a failed attempt at a joke, or are you really that dense?
2. Re:Just one question... by kd5ujz · 2007-09-10 10:51 · Score: 1
  
  How often does landing gear fail during takeoff? (French aircraft aside)
  
  --
  -William
  God is everything science has yet to explain.
3. Re:Just one question... by Anonymous Coward · 2007-09-10 12:51 · Score: 0
  
  From the video, it looks like a) this plane has NO landing gear, and b) prop rotation sticks out several feet below the lower surface, so I don't see how it could land without at least scraping up the props...
4. Re:Just one question... by fractoid · 2007-09-10 15:33 · Score: 1
  
  I'd guess you lock the props horizontal and perform a water landing? Something that light has got to float. Hell, it could probably land on wet grass with no damage.
  
  --
  Rampant carbon sequestration destroyed the Dinosaurs' tropical paradise. I'm here to help repair the damage.
5. Re:Just one question... by petermgreen · 2007-09-10 22:21 · Score: 1
  
  Afaict the time when landing gear tends to fail is deployment. when the plane is on the ground the gear is already deployed and holding the weight of the plane.
  
  --
  note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't register
What constitutes Solar Power? by mweier · 2007-09-10 08:59 · Score: 4, Interesting

Obviously solar panels feed it to maintain energy stores; however since it must store this energy in a battery of some sort, is it required that the batteries be empty when launched? If not, what's to stop someone with a major pile of pre-charged solar-rechargeable batteries from tacking one solar panel on top & calling it a solar vehicle even if it could never fully charge those during use? Not accusing these folks of doing that but just curious about how they classify solar vehicles...

--
digital artist, 3D animator, web designer, and otherwise technological creative type....
1. Re:What constitutes Solar Power? by TheRaven64 · 2007-09-10 09:16 · Score: 1
  
  I'm not sure why going two nights is such an achievement. Surely you charge the batteries in the first day, discharge them the first night, and then repeat on the second day and night. Unless the batteries are not fully discharged for takeoff, as you say.
  
  --
  I am TheRaven on Soylent News
2. Re:What constitutes Solar Power? by larkost · 2007-09-10 09:18 · Score: 1
  
  There is a natural limiter here: batteries are very heavy and a battery-powered (heavier-than-air) aircraft is unlikely to ever get close to this record. That is something that is unlikely to change before things change enough to make this sort of record meaningless anyways.
3. Re:What constitutes Solar Power? by QuantumG · 2007-09-10 09:31 · Score: 1
  
  There's these things called clouds right, and they obscure the thing called the Sun which the solar power comes from.. and, as such, no two days are the same.
  
  --
  How we know is more important than what we know.
4. Re:What constitutes Solar Power? by Anonymous Coward · 2007-09-10 09:31 · Score: 0
  
  Everything is easy until you try to do it. A problem is the 'the batteries' are to heavy to keep in flight under their own power over night easily.
5. Re:What constitutes Solar Power? by agingell · 2007-09-10 09:36 · Score: 2, Interesting
  
  The record in question actually has nothing to do with solar power. It is purely an endurance record for longest flight time under continuous power. The Global Hawk is actually powered by a turbojet engine and normal Jet A1 fuel.
  
  Solar powered aircraft have been quite successful for some time for instance the Pathfinder and Helios aircraft by NASA the biggest issue is to get through the night on battery power. I believe the NASA aircraft had to resort to gliding and soaring which this aircraft does not.
  
  A purely battery aircraft would fall out of the sky in a relatively short period of time, it would probably not even get to altitude before having to glide home.
  
  Typically solar vehicles have to start races with the energy store empty however this is very unlikely in this case as they were just doing some tests. The flight tests all seem to end when there is an issue with the aircraft or the weather is not looking good. So it may well be the case that it would not be able to stay airborne indefinitely.
6. Re:What constitutes Solar Power? by XaXXon · 2007-09-10 09:41 · Score: 1
  
  Charge as many batteries with as much power as you want - you have to get them off the ground. The problem is that right now batteries are heavy and not efficient enough. It's the same problem with getting rockets into space. You have to carry the energy you want to use later.
  
  This is something that will get solved - the only interesting part is 'when'. The fact that it's happening now is what's interesting.
7. Re:What constitutes Solar Power? by Somegeek · 2007-09-10 11:07 · Score: 1
  
  Not many clouds above 50,000 ft. That's where this thing flies.
  
  --
  And as you tread the halls of sanity, You feel so glad to be, Unable to go beyond. I have a message, From another time..
8. Re:What constitutes Solar Power? by Jartan · 2007-09-10 11:53 · Score: 1
  
  There is a natural limiter here: batteries are very heavy and a battery-powered (heavier-than-air) aircraft is unlikely to ever get close to this record. That is something that is unlikely to change before things change enough to make this sort of record meaningless anyways.
  
  Why use batteries though? What about miniature flywheels and what not? Batteries would be the last type of energy storage I'd look at for this sort of application.
9. Re:What constitutes Solar Power? by mr_matticus · 2007-09-10 11:56 · Score: 1
  
  That would require that the craft generate enough solar power to charge the batteries AND power the craft at the same time. The loss of energy in transferring from solar cells to batteries and drawing from batteries again is not inconsiderable, and the motors need to run in daylight, too.
  
  At 20% overall efficiency (assuming arbitrary battery losses from a 30% solar cell), you need to be able to collect ten times the operational requirements of your vehicle in order to pull off what you describe. That's quite a lot of power.
10. Re:What constitutes Solar Power? by Unique2 · 2007-09-10 14:43 · Score: 1
  
  According to the Wikipedia article on energy density, flywheels have a lower energy density than lithium ion batteries. I guess there would also be the additional complication of having to use multiple flywheels to balance the angular momentum so the craft can be steered resulting in additional gearing adding weight and friction.
  
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  No trees were harmed in the posting of this message. However, a great number of electrons were terribly inconvenienced.
11. Re:What constitutes Solar Power? by jtcm · 2007-09-10 14:52 · Score: 1
  Why use batteries though? What about miniature flywheels and what not?
  
  You're right, flywheels can store the same energy using less mass, and can be more efficient. I suspect, though, that heavey flywheels on a light airframe would make for some difficult gyroscopic effects.
  
  In fact, see this page with a Flywheel vs Battery Energy Storage comparison. It's just past halfway down the page:
  
  Flywheels are preferred over conventional batteries in many aerospace applications because of the following benefits
  Flywheel vs Battery Energy Storage
  
  Energy Storage Characteristic: 5 to 10+ times greater specific energy
  Resulting Benefits: Lower mass
  
  Energy Storage Characteristic: 85-95% round-trip efficiency
  Resulting Benefits: More usable power, lower thermal loads, compared with < 70-80% for battery system
  
  (there's more on the page...)
  
  Then there's the kicker at the bottom:
  
  The huge gyroscopic forces of these high speed flywheels are an added complication. Practicalities have so far prevented the large scale adoption of flywheels for portable applications.
  
  In the immortal words of Kari Byron: "Oh, the Newton's laws! We forgot the Newton's laws!"
  --
  @ASP.NET's parent-teacher meeting: "Little Johnny.NET is very bright, but he doesn't play well with others."
12. Re:What constitutes Solar Power? by TheRaven64 · 2007-09-10 22:10 · Score: 1
  
  Right. I understand why flying through the night is impressive, but why is flying through a second night impressive? If on day 1 you can generate enough power to fly through night 1, why is it hard to generate enough power on day 2 to fly through night 2? Unless, of course, the battery is charged prior to take off, at which point calling it solar powered is not really accurate; solar assisted might be better.
  
  --
  I am TheRaven on Soylent News
13. Re:What constitutes Solar Power? by petermgreen · 2007-09-10 22:32 · Score: 1
  
  The other big problem with flywheel batteries is failure. If the complicated superconducting bearing and vacum systems fail the energy could be released very rapidly. Add to that the fact that for maximum energy density the flywheel is probablly on the brink of flying apart and the potential for carnage is obvious.
  
  --
  note: i'm known as plugwash most places but i screwd up registering that here somehow in the past and now can't register
14. Re:What constitutes Solar Power? by salec · 2007-09-10 22:59 · Score: 1
  
  You can mount the flywheel in gyroscope gimbals, thus decoupling it from the airframe (and you also get a gyroscope for free :P )
15. Re:What constitutes Solar Power? by Eivind · 2007-09-11 01:17 · Score: 1
  
  Nothing prevents that. But a battery doesn't contain even nearly enough energy to fly for 2 nights and 3 days. So if you did this, your plane would come back down once the battery was empty, after a few hours at best.
  
  The endurance-record for not-collecting-energy is the Global Hawk, it uses jet-fuel which has a lot more energy relative to weight compared to batteries, and it still manages "only" max 30 hours.
  
  I'm guessing the max for a batteries-only plane would be in the single-digit-hours, indeed for this and similar planes the challenge is to survive the night on batteries-only. They don't quite manage, but additionaly they gain altitude at daytime and lose it at nigth-time, which also serves as a energy-storage of sorts.
16. Re:What constitutes Solar Power? by Eivind · 2007-09-11 01:22 · Score: 1
  
  Your hunch is correct; the plane is charged prior to take-off, which it needs to be because on the first day it has *two* tasks, one is to charge the batteries, the other is to gain 15-18000 meters of altitude. It would be unable to do both, but manages to do one of the two.
  
  And that's why *2* nights is interesting -- on the first day/night cycle the plane demonstrates that it can climb to altitude without using the batteries, and that it can survive the night on batteries-only.
  
  On the second day/night cycle it demonstrates that in one day it can recharge the batteries sufficiently to survive another night.
17. Re:What constitutes Solar Power? by LoudMusic · 2007-09-11 04:51 · Score: 1
  
  It still has to heft those batteries. In my solar-uneducated-opinion, if it made it through one night and was able to recharge and make it through the next it should be able to do that indefinitely. Assuming optimal conditions. It could also take advantage of flying west in the sunlight and east in the darkness to pick up a few extra minutes of Sunlight.
  
  I'm wondering if there are plans to put these things in motion with cameras equipped for continual updating of surface images in populated areas. A team of these aircraft could be relaying massively high resolution images constantly.
  
  --
  No sig for you. YOU GET NO SIG!
Ann Rice's vampires do this by peter303 · 2007-09-10 09:00 · Score: 1, Offtopic

The more powerful vampires are able to follow the night and and be awake for the perpetual night.
1. Re:Ann Rice's vampires do this by ScrewMaster · 2007-09-10 09:06 · Score: 2, Insightful
  
  Yes, but then again vampires aren't exactly solar powered. Unless you count the motivation to avoid the Sun as a power source.
  
  --
  The higher the technology, the sharper that two-edged sword.
2. Re:Ann Rice's vampires do this by Daimanta · 2007-09-10 09:16 · Score: 1
  
  Vampires: anti-Solar powered (TM)
  
  --
  Knowledge is power. Knowledge shared is power lost.
3. Re:Ann Rice's vampires do this by Dirtside · 2007-09-10 10:30 · Score: 1
  
  Yes, but then again vampires aren't exactly solar powered.
  
  As it happens, Solar Powered Vampires is opening at the Whisky a Go Go tomorrow night.
  
  --
  "Destroy science and religion. Science would re-emerge exactly the same; but not religion." - Penn Jillette, paraphrased
Re:lol by Dunbal · 2007-09-10 09:01 · Score: 2, Funny

I, for one, welcome our [can't think of a damn thing witty] overlords.

Robotic, solar powered flying overlords?

--
Seven puppies were harmed during the making of this post.
Obligatory by Anonymous Coward · 2007-09-10 09:16 · Score: 0

Does it run Windows?

Your tax dollars at work: Letting a U.K. gunrunner fly from the U.S.
Innovative solution to the nighttime problem by Anonymous Coward · 2007-09-10 09:21 · Score: 5, Funny

A series of halogen lights mounted along the wings are illuminated at night to power the solar array.
1. Re:Innovative solution to the nighttime problem by XaXXon · 2007-09-10 10:11 · Score: 2, Funny
  
  Too bad it's not metal.. you could just put a magnet in front and above the plane to keep it up and and moving.
2. Re:Innovative solution to the nighttime problem by Yvanhoe · 2007-09-10 19:17 · Score: 1
  
  Brilliant !
  
  --
  The Wise adapts himself to the world. The Fool adapts the world to himself. Therefore, all progress depends on the Fool.
What the? by veganboyjosh · 2007-09-10 09:21 · Score: 2, Insightful

enouhh

What the hell kind of spelling mistake is that? Come on editors, at least READ the edited summary...
1. Re:What the? by greg_barton · 2007-09-10 09:25 · Score: 1
  
  No furking shyte. Wish I had mod points.
2. Re:What the? by coldmist · 2007-09-10 09:28 · Score: 1
  
  They did! They changed it from 'enuf' to 'enougg' for us.
  
  --
  Don't steal. The government hates competition.
3. Re:What the? by cuantar · 2007-09-10 10:08 · Score: 3, Informative
  
  The best part is, when the story was first posted, it was "engouh" until it was corrected to read "enouhh."
  
  --
  Legalize it.
4. Re:What the? by Kelz · 2007-09-10 10:16 · Score: 1
  
  I'd imagine some editors actually have a sense of humor and like to poke fun at grammar/spelling trolls.
5. Re:What the? by HTH+NE1 · 2007-09-10 11:21 · Score: 1
  
  Indeed, engouh is enouhh!
  
  --
  Oh, say does that Star-Spangled Banner entwine / The myrtle of Venus with Bacchus's vine?
6. Re:What the? by MobileTatsu-NJG · 2007-09-10 12:20 · Score: 0, Troll
  
  "What the hell kind of spelling mistake is that? Come on editors, at least READ the edited summary... (Score:4, Insightful)"
  
  What the hell kind of moderation is that? It's a silly typo, it's already been commented on, and the complaint about hte typo adds nothing to the discussion.
  
  You found something to nitpick and a few peeps had moderation points burning a hole in their pockets. Whoop-de-fucking-doo. Let's just pause the discussion so everybody can golf-clap.
  
  --
  
  "I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
7. Re:What the? by MobileTatsu-NJG · 2007-09-10 13:00 · Score: 1
  
  "No furking shyte. Wish I had mod points."
  
  Why? So you could mod up the post bitching about a frivilous typo instead of working to lower the signal-to-noise-ratio?
  
  --
  
  "I like to lick butts!" by MobileTatsu-NJG (#32700246) (Score:5, Informative)
I for one by Anonymous Coward · 2007-09-10 09:22 · Score: 0

welcome our airborne overloards as they return to their classical means of mobility.
Question? by SnarfQuest · 2007-09-10 09:22 · Score: 1

Does this bring us closer to personel flying cars, that have been promised to us for decades?

--
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
1. Re:Question? by Unkyjar · 2007-09-11 07:52 · Score: 1
  
  Here's an article about flying cars in the CBS news: http://www.cbsnews.com/stories/2005/04/15/60minutes/main688454.shtml
  
  Here's a link to the Moller Skycar: http://www.moller.com/skyc.htm
What if it flew in the opposite direction of sun by CrazyJim1 · 2007-09-10 09:22 · Score: 2, Insightful

During the day, it flys with the sun, to get a longer day. Then during the night, it flys in the opposite direction in order to achieve a shorter night.

--
God spoke to me.
Re:lol by Opportunist · 2007-09-10 09:23 · Score: 2, Funny

Darn memes. Engouh already!

--
We used to have a Bill of Rights. Now, with the rights gone, all we have left is the bill.
Glass houses... by billbaggins · 2007-09-10 09:24 · Score: 5, Funny

Looked at your /. username lately?

--
"The best argument against democracy is a five minute chat with the average voter."
--Winston Churchill
1. Re:Glass houses... by k31bang · 2007-09-10 10:21 · Score: 1
  
  I'm stuck in basement of a glass house with no stones to throw to get out, you insensitive clod!
  
  --
  -+-=-+-=-+-=-+-=-+-=-+ *** http://www.mountainfort.com *** +-=-+-=-+-=-+-=-+-=-+-
2. Re:Glass houses... by InvisblePinkUnicorn · 2007-09-10 11:33 · Score: 1
  
  "Looked at your /. username lately?"
  
  The i is not missing, it is simply invisible, out of reverence for Her Holy Horn (H^3).
  
  Either that, or the full username was already taken and this looked the most like that.
what is it good for? by symbolset · 2007-09-10 09:46 · Score: 1

Recon

--
Help stamp out iliturcy.
Tipping Point by Doc+Ruby · 2007-09-10 09:47 · Score: 2, Informative

This is the watershed performance for solar powered vehicles. If it can go through 2 nights, it can go through any number of them. Though we're still on the sunny side of the equinox (2 weeks prior), so there is a little more time charging in the sunshine than discharging in the darkness.

When a vehicle can go 24h on only 12h prior charge, that will be the next major milestone. Still not enough for uninterrupted travel past a latitude where nights are longer than a whole couple of days (depending on the battery - a yearlong discharge battery would be good anywhere with current performance).

The next parallel milestone is automated rechargers leaving ground charging stations to recharge the permanently aloft vehicle in flight.

After that, there's not a lot more demand for improvement, except overall efficiency for carrying heavier loads and more demanding equipment.

Like a network of these permanently in high atmosphere propelling solar sails through the solar system and down to blimp spaceports.

--
--
make install -not war
1. Re:Tipping Point by XaXXon · 2007-09-10 10:14 · Score: 3, Informative
  
  Mathematically that's not quite true. If it had some amount of initial charge it could be using some percentage of that in order to make it through each night. Perhaps that number is 50% each night :)
  
  I don't know if that is the case here.. just saying that it doesn't necessarily follow that the plane can stay up indefinitely.
2. Re:Tipping Point by loic_2003 · 2007-09-11 00:34 · Score: 1
  
  I'm not sure exactly what defines flight on solar power, but would it be permittable to have the craft gain altitude during the day and have a low rate of decent (ie like a glider) so it can remain aloft throughout the night whilst using much less power than during the day? This would mean that it wouldn't have it's motors running constantly, thus reducing the issue of the day:night ratio. Would using thermals and whatnot to stay up be considered 'cheating'?
  
  --
  http://www.frenchgeek.com/
3. Re:Tipping Point by Doc+Ruby · 2007-09-11 03:17 · Score: 1
  
  That's an interesting idea: use excess daytime solar power to gain altitude, storing power in the entire craft gravitationally, rather than in a battery. Perhaps using some small amount of power (while the sunlight is available) to change the wing shape from whatever best suits the primary application into one that glides farther (falls slower). Gravitational storage rather than battery means the entire vehicle is lighter, therefore more efficient, if a minimum of mass is dedicated to accommodating the nighttime storage "on the top shelf".
  
  In fact, that approach suggests some other alternatives. Perhaps some material could be used to make the vehicle lighter than air at night. But which contracts its volume into a more efficient shape when solar power is available. Another strategy could make the vehicle use a very fast and efficient shape to fly quickly away from the approaching night, if speed can exceed 1000 MPH, to return when daylight returns.
  
  If one of these solutions doesn't conflict with the primary mission of the vehicle, it could work well. Most of them exclude quite a lot of applications during the night, and could be cost or tech prohibitive.
  
  But we're clearly on the cusp of a completely new era in something fundamental. We've been flirting with it for a century, since we first achieved flight. But is something that stays aloft permanently really a vehicle? Or isn't it really more like a place, even if it's in motion? If we deploy a whole bunch of new places that are well above the ground, haven't we in a way raised the upper surface of the Earth? That way of looking up has been coming for a while, with artificial satellites in a way offering at least the highest "mountaintops", but we don't see them or think of them much except in the abstract - and practically never visit them. But if it becomes common for most people to either visit a floating platform, or just know enough people who do (or see it on TV as often as we see, say, ocean cruises), then we might change our basic sense of our own place "on" the planet. We might start to feel like we're embedded in the planet. And start to think the planet is "wide open" again, with a third dimension now available in a way it hasn't been with mere "skyscrapers" still rooted to the ground and isolated from one another except by going back to the surface.
  
  This simple incremental advance, solar powered vehicles discharging slower than charging, through a couple of nights, could move us through what I called a "tipping point". Beyond which we might have a revolutionary change in much more than a battery.
  
  --
  --
  make install -not war
Blimp by Anonymous Coward · 2007-09-10 09:49 · Score: 0

What would be really useful is a solar powered blimp to replace satellites.

There's Billions waiting for something like that.
1. Re:Blimp by Farmer+Tim · 2007-09-10 14:12 · Score: 1
  
  What would be really useful is a solar powered blimp to replace satellites.
  
  There's Billions waiting for something like that.
  
  They're already advertising.
  
  --
  Blank until /. makes another boneheaded UI decision.
Helios was cooler by iiii · 2007-09-10 09:49 · Score: 1

Helios was way cooler. It was headed for continuous flight several years ago. Unfortunately it met an untimely end. I think NASA should rebuild it and continue the work. Some of the, um, pundits, on this thread don't seem to have the faintest about how it could work, but it is an awesome concept: solar panels collect all day, generating enough power to fly and to charge the hydrogen fuel cells, which power the craft all night. And it can fly high enough to be above the weather, so the sunshine will be consistent. Wicked.
Some links.

--
Light cup, beer drink, thin so chain, neck turtle fat, man I won't say it again
Talk about doing it the hard way by Colin+Smith · 2007-09-10 10:00 · Score: 2, Interesting

Replace the wings with an envelope and you can stay up for weeks.

--
Deleted
1. Re:Talk about doing it the hard way by Eivind · 2007-09-11 01:25 · Score: 1
  
  True, but you're less maneuvrable. A compromise may be worthwhile, building a plane like this, but seal it and fill it with helium. Dunno if the volume is enough that the added lift would outweigh the extra mass for sealing it though.
2. Re:Talk about doing it the hard way by afidel · 2007-09-11 02:34 · Score: 1
  
  There's that whole problem of speed, I assume even an ultralight plane like this can make better headway then even the fastest semi rigid airships like the Zeppelin NT @ 125 km/h.
  
  --
  There are 4 boxes to use in the defense of liberty: soap, ballot, jury, ammo. Use in that order. Starting now.
Grousing about submissions by kwerle · 2007-09-10 10:04 · Score: 4, Informative

Not only did I submit this story with no type-o's, last night, but I also made reference to the previous solar powered flight that lasted 2 nights, which this submission implies never happened before.

Though the previous one also did gliding/non-powered flight part of the time. Still, up for 48 hours.
Re:What if it flew in the opposite direction of su by Ogive17 · 2007-09-10 10:12 · Score: 1

While I understand your point, anything moving that slow will wind up just a few miles from the origin if you fly west with sunlight and east in the dark.

--
"Action without philosophy is a lethal weapon; philosophy without action is worthless."
Re:What if it flew in the opposite direction of su by Loke+the+Dog · 2007-09-10 10:48 · Score: 1

Its not fast enough for it to make that much of a difference. If you fly it far enough from the equator though, you can get pretty much constant sunlight, which seems like a better trick to pull if you want to cheat a little :)
AC Propulsion did this a while back by Thagg · 2007-09-10 11:03 · Score: 3, Informative

Check out this press release.

AC Propulsion said that they could do it indefinitely, but their pilots got worn out.

Thad Beier

--
I love Mondays. On a Monday, anything is possible.
Huh??? by Gription · 2007-09-10 11:38 · Score: 2, Insightful

I think the quantity of energy that it takes to go over 1000 miles an hour is going to be pretty hard to collect in a solar powered plane.
1. Re:Huh??? by BigDogCH · 2007-09-11 01:34 · Score: 1
  
  Well, at least they should travel in that direction, adding maybe an hour to their day. Then, at dusk, turn around, reducing the length of the night. They could even then land where they started....after enough days anyway.
  
  I assume the problem is pilots, so this one would have to be automated.
2. Re:Huh??? by MM_LONEWOLF · 2007-09-11 06:21 · Score: 1
  
  You can say that the problem would be pilots, but looking at it from the point of view as the son of an air force lieutenant, and a private pilot, there are hundreds of other variables. Wind speed, air pressure, temperature, turbulence, air currents, ..... the list could go on for days. Could a mondern-day computer handle it? Probably. But there is a reason that the best they've gotten out of a solar powered UAV is slightly over 50 hours.
  
  --
  To live without killing is a thought which could electrify the world, if men were capable of staying awake long enough.
Re:AC Propulsion did this a while back [2yrs ago!] by Thagg · 2007-09-10 11:52 · Score: 1

I hadn't read the article -- I remember it when it was done, but I had thought it was just recently.

This was done by AC Propulsion two years ago.

Thad

--
I love Mondays. On a Monday, anything is possible.
Attaining altitude by drwho · 2007-09-10 11:58 · Score: 3, Interesting

Like many space and exotic aircraft, it must have to expend a lot of energy to get to its cruising altitude. Once that's done, conditions should become easier. Would it be considered 'cheating' to launch such a perpetual flying machine with an assistance device? That could be either disposable batteries that are jettisoned when discharged, or some chemcal rocket engine, or a jet engine, or have it launched from an aircraft.

Insolation is going to me much better at high altitudes. I just hope the photovoltaic cells are designed to take advantage of the increased amount of energy available in the UV spectrum. How about filling the free space in the wings with hydrogen? That might help lift a little, at least from the ground. However, there would have to be some way of dealing with the reduced pressure at operational altitude.

There's been a lot of interesting improvements in PV efficiency lately. However, most of these seem to only happen when the cell is operated at insolation far above normal. These are obtained by focusing the sunlight. Unfortunately, all of the technologies I know of which could do this are heavier than simply adding more, less efficient cells which operate at normal insolation or the slight improvement that high-atmosphere flight provides.
1. Re:Attaining altitude by jeti · 2007-09-10 18:50 · Score: 1
  
  I think the ultimate goal is not to establish a record, but to
  use these planes as communication links or surveillance platforms.
  So who cares how you get the bird up as long as you can do it on
  short notice and with acceptable costs?
2. Re:Attaining altitude by mks113 · 2007-09-11 01:20 · Score: 1
  
  Hang it under a balloon to get it to altitude. You'd lose a bit of altitude when it launched at zero forward speed though...
3. Re:Attaining altitude by RealGrouchy · 2007-09-11 01:37 · Score: 1
  
  Anyone who's seen just one episode of that "Guinness World Records" TV show knows that no record is "cheating" if you qualify it enough.
  
  - RG>
  
  --
  Hey pal, this isn't a pleasantforest, so don't waste my time with pleasantries!
Obviously British mods are easy to displease! by Anonymous Coward · 2007-09-10 14:06 · Score: 0

An excellent example of the much-vaunted English sense of humor at work, huh?
Math correction by Anonymous Coward · 2007-09-10 17:42 · Score: 0

2 * pi * (R + h) - 2 * pi * R = 2 * pi * h

In other words, 2 * pi * 5.68 mi = 35.7 mi.
An alternate solar flight plan by Whiteox · 2007-09-10 20:49 · Score: 1

A way to have a solar plane in maximum light is to follow the sun along an equatorial path, allow the 'night' to overtake the plane (as it would in any case), then turn the plane 180 degrees and run into the 'day', turn 180 degrees and follow the sun, then wait for the night to catch up etc etc.
Repeat ad nauseum.

Thus, the plane would be in the light for many more hours than a static diurnal flight plan. Mind you it won't get you to a destination directly. Like taking 2 steps forward and one step back, but it will work.

Simple really!

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Don't be apathetic. Procrastinate!
Props are not counter-rotating? by mnemotronic · 2007-09-11 03:01 · Score: 1

In the video, the props both appear to turn CCW (viewed from behind the craft) and turn very slow. I wonder why they didn't go with props that turn in opposite directions?

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The Russians have won. They have made the world a cesspool of distrust, greed, fear and hate.
First 2 night Heavier than Air Craft by Maximum+Prophet · 2007-09-11 03:16 · Score: 1

Better check the record books. I'm sure that this is the first heavier-than-air craft to do this. Unmanned ballons have stayed up for much longer and I sure a remote controlled Zepplin could stay up much longer.
The article says that it landed 54 hours later, but didn't specify where. If this thing doesn't have enough power to keep up with the winds above a city, it won't be much use as a satellite replacement. However if it can keep up and fly in circles above the weather it'd make an ideal replacement for communications satellites. If these can be made cheaply enough, they'd be the end-all of last mile broadband for rural areas.

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All ideas^H^H^H^H^Hprocesses in this post are Patent Pending. (as well as the process of patenting all postings)
What about wind? by Anonymous Coward · 2007-09-11 04:30 · Score: 0

Wouldn't going in the direction of the wind be a better use of saving power rather than going the opposite way at night? Wouldn't the night go by quicker if you fly with the wind?
whats with cars? by AlgorithMan · 2007-09-11 09:20 · Score: 1

an 18 meter solar plane flying for over 50 hours...
and still we don't have solar cars...
the oil industry must bribe politicians...

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The MAFIAA is a bunch of mindless jerks who will be the first up against the wall when the revolution comes
1. Re:whats with cars? by merreborn · 2007-09-11 10:37 · Score: 1
  
  I'm sure I'm wasting my time responding to such an obvious troll, but just incase anyone else happens to be mislead by your comment:
  
  Consumers expect certain characteristics from cars that just aren't possible with 30 square feet of solar panels. Namely, we expect cars to accelerate from 0 to 60 in about 10 seconds, 20 seconds at worst, that they be able to maintain 60 mph for at least 300 miles on a single "charge", and that they be able to carry loads of 1/4 to 1/2 ton at minimum (two to four adults).
  
  To do all this, we use powerful engines -- the engine in a small car produces (at peak) around 100 kilowatts of power -- with massive energy reserves -- a 10 gallon tank of gasoline contains something on the order of 360 killowatt hours of energy.
  
  Now, by way of comparison, the sun's rays project an average of 1 kilowatt on a square meter of the earth's surface. Modern solar panels can only capture 20 - 40% of that -- 200 to 400 watts. You could fit at best a couple of square meters of solar panels on the roof of your car, providing you with far less than even 5% of the peak power of the engine in the cheapest Honda. Even with a hypothetical 100% efficiency solar cell, you're still dealing with far less power.
  
  It's simply physically impossible to build a purely solar powered car that would be legal to drive on the interstate. Accelerating hundreds/thousands of pounds of passengers and metal from 0 mph to 60 mph in 5-15 seconds takes far more energy than you can capture from the sun with a few square meters of collectors.