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Solar Craft Flies Through Two Nights

ScuttleMonkey posted more than 6 years ago | from the nasa-awash-with-envy dept.

Power 156

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."

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An idea (1)

Anonymous Coward | more than 6 years ago | (#20544515)

Couldn't a solar craft just follow the sun around the earth, indefinitely?

Re:An idea (1)

corsec67 (627446) | more than 6 years ago | (#20544551)

At a high enough altitude, sure.....

Huh??? (2, Insightful)

Gription (1006467) | more than 6 years ago | (#20546453)

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.

Re:An idea (3, Informative)

dartboard (23261) | more than 6 years ago | (#20544567)

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.

Re:An idea (4, Interesting)

everphilski (877346) | more than 6 years ago | (#20544789)

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.

Re:An idea (1)

91degrees (207121) | more than 6 years ago | (#20544797)

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.

Re:An idea (4, Informative)

dougmc (70836) | more than 6 years ago | (#20545023)

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 [plannet21.com] 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.

Re:An idea (1)

CastrTroy (595695) | more than 6 years ago | (#20546405)

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.

Re:An idea (1)

dougmc (70836) | more than 6 years ago | (#20546529)

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.

Re:An idea (3, Informative)

LWATCDR (28044) | more than 6 years ago | (#20545027)

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.

Re:An idea (3, Funny)

flyingsquid (813711) | more than 6 years ago | (#20545431)

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.

Re:An idea (3, Informative)

Daedone (981031) | more than 6 years ago | (#20545651)

Lisa, in this house we OBEY the laws of thermodynamics!

Re:An idea (1)

Cassius Corodes (1084513) | more than 6 years ago | (#20546187)

Already patented - Along with fans that blow air into wind power plants.

Re:An idea (1)

Toutatis (652446) | more than 6 years ago | (#20546111)

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.

Re:An idea (0, Troll)

stevenvi (779021) | more than 6 years ago | (#20546377)

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.

Re:An idea (3, Informative)

Manhigh (148034) | more than 6 years ago | (#20544581)

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.

Re:An idea (2, Informative)

Gadgetfreak (97865) | more than 6 years ago | (#20545071)

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.

Re:An idea (0)

Anonymous Coward | more than 6 years ago | (#20545231)

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.

Re:An idea (1)

CastrTroy (595695) | more than 6 years ago | (#20546489)

Just as a reference point, the Concorde [wikipedia.org] 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?

Re:An idea (0)

Anonymous Coward | more than 6 years ago | (#20545117)

Erm... this depends on your latitude... I can walk west around the north pole faster than the sun...

Re:An idea (0)

Anonymous Coward | more than 6 years ago | (#20545135)

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.

Re:An idea (0)

Anonymous Coward | more than 6 years ago | (#20545253)

Oops, I meant not very different than the circumference at the ground at the equator.

Re:An idea (1)

stoolpigeon (454276) | more than 6 years ago | (#20544585)

they probably can't go that fast. then there is weather, wind, what not.

Re:An idea (2, Informative)

SatanicPuppy (611928) | more than 6 years ago | (#20544687)

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.

Re:An idea (1)

caramelcarrot (778148) | more than 6 years ago | (#20544611)

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.

Re:An idea (1)

Anonymous Coward | more than 6 years ago | (#20544931)

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.

Re:An idea (2, Interesting)

rleibman (622895) | more than 6 years ago | (#20545821)

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.

Re:An idea (0)

Anonymous Coward | more than 6 years ago | (#20545235)

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. :)

Ann Rice's vampires do this (1, Offtopic)

peter303 (12292) | more than 6 years ago | (#20544761)

The more powerful vampires are able to follow the night and and be awake for the perpetual night.

Re:Ann Rice's vampires do this (2, Insightful)

ScrewMaster (602015) | more than 6 years ago | (#20544853)

Yes, but then again vampires aren't exactly solar powered. Unless you count the motivation to avoid the Sun as a power source.

Re:Ann Rice's vampires do this (1)

Daimanta (1140543) | more than 6 years ago | (#20544959)

Vampires: anti-Solar powered (TM)

Re:Ann Rice's vampires do this (1)

Dirtside (91468) | more than 6 years ago | (#20545773)

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.

Re:An idea (1)

Spy der Mann (805235) | more than 6 years ago | (#20544799)

Couldn't a solar craft just follow the sun around the earth, indefinitely?

Until the next solar eclipse, that is. :)

Re:An idea (1)

msevior (145103) | more than 6 years ago | (#20547373)

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.

What the...? (0, Offtopic)

Pojut (1027544) | more than 6 years ago | (#20544543)

engouh


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

Re:What the...? (0)

Anonymous Coward | more than 6 years ago | (#20544597)

Sho 'Nuff!

Re:What the...? (1)

ch-chuck (9622) | more than 6 years ago | (#20544635)

Hmm, looks like a word from the Klingon:

Dah, engouh mojaqmeyvam divusnisbe

Re:What the...? (2, Funny)

Chapter80 (926879) | more than 6 years ago | (#20544659)

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 [slashdot.org] earlier.

Re:What the...? (4, Funny)

Gertlex (722812) | more than 6 years ago | (#20544667)

engouh


What the hell kind of spelling mistake is that?
A typo?

more (4, Interesting)

stoolpigeon (454276) | more than 6 years ago | (#20544545)

This BBC article has good info. [bbc.co.uk]
 
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.

Smelly cock (-1, Troll)

Anonymous Coward | more than 6 years ago | (#20544757)

Smelly cock, smelly cock
Who is sucking you?
Smelly cock, smelly cock
You get no cunt...

Re:more (0)

Anonymous Coward | more than 6 years ago | (#20546771)

There are many R/C craft that have flown for MUCH more than 30 hours.

Solar powered aircraft are effectively useless (0)

Anonymous Coward | more than 6 years ago | (#20544573)

nt

What good is it? (0)

Anonymous Coward | more than 6 years ago | (#20544587)

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.

Re:What good is it? (4, Insightful)

stoolpigeon (454276) | more than 6 years ago | (#20544625)

it's good for learning things to be used in later vehicles that will accomplish, you know, stuff

"What good is it?" (-1, Offtopic)

Anonymous Coward | more than 6 years ago | (#20544633)

It makes the Brits feel good. They're a simple people and easy to please.

Re:What good is it? (1, Flamebait)

Amouth (879122) | more than 6 years ago | (#20544655)

it is called a step in the right direction....... if you cant' see that then please open your eyes

Re:What good is it? (1)

forkazoo (138186) | more than 6 years ago | (#20545827)

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.

Re:What good is it? (0)

Anonymous Coward | more than 6 years ago | (#20544813)

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.

Re:What good is it? (3, Funny)

Dunbal (464142) | more than 6 years ago | (#20544989)

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!

what is it good for? (1)

symbolset (646467) | more than 6 years ago | (#20545303)

Recon

Re:What good is it? (0)

Anonymous Coward | more than 6 years ago | (#20545761)

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.

Re:What good is it? (1)

Daedone (981031) | more than 6 years ago | (#20547261)

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?

engouh solar energy (4, Funny)

InvisblePinkUnicorn (1126837) | more than 6 years ago | (#20544605)

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."

Glass houses... (5, Funny)

billbaggins (156118) | more than 6 years ago | (#20545047)

Looked at your /. username lately?

Re:Glass houses... (1)

k31bang (672440) | more than 6 years ago | (#20545669)

I'm stuck in basement of a glass house with no stones to throw to get out, you insensitive clod!

Re:Glass houses... (1)

InvisblePinkUnicorn (1126837) | more than 6 years ago | (#20546419)

"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.

Just one question... (1, Funny)

Anonymous Coward | more than 6 years ago | (#20544639)

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!

Re:Just one question... (0)

Anonymous Coward | more than 6 years ago | (#20544885)

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?

Re:Just one question... (1)

kd5ujz (640580) | more than 6 years ago | (#20546011)

How often does landing gear fail during takeoff? (French aircraft aside)

Re:Just one question... (0)

Anonymous Coward | more than 6 years ago | (#20547183)

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...

lol (-1, Offtopic)

thatskinnyguy (1129515) | more than 6 years ago | (#20544705)

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

Re:lol (2, Funny)

Dunbal (464142) | more than 6 years ago | (#20544781)

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

      Robotic, solar powered flying overlords?

Re:lol (-1, Redundant)

zippthorne (748122) | more than 6 years ago | (#20544855)

Autonomous overhead overlords?

Re:lol (2, Funny)

Opportunist (166417) | more than 6 years ago | (#20545031)

Darn memes. Engouh already!

What constitutes Solar Power? (4, Interesting)

mweier (135569) | more than 6 years ago | (#20544745)

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...

Re:What constitutes Solar Power? (1)

TheRaven64 (641858) | more than 6 years ago | (#20544963)

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.

Re:What constitutes Solar Power? (1)

QuantumG (50515) | more than 6 years ago | (#20545109)

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.

Re:What constitutes Solar Power? (1)

Somegeek (624100) | more than 6 years ago | (#20546191)

Not many clouds above 50,000 ft. That's where this thing flies.

Re:What constitutes Solar Power? (0)

Anonymous Coward | more than 6 years ago | (#20545125)

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.

Re:What constitutes Solar Power? (1)

mr_matticus (928346) | more than 6 years ago | (#20546607)

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.

Re:What constitutes Solar Power? (1)

larkost (79011) | more than 6 years ago | (#20544983)

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.

Re:What constitutes Solar Power? (1)

Jartan (219704) | more than 6 years ago | (#20546585)

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.

Re:What constitutes Solar Power? (2, Interesting)

agingell (931397) | more than 6 years ago | (#20545191)

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.

Re:What constitutes Solar Power? (1)

XaXXon (202882) | more than 6 years ago | (#20545245)

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.

Obligatory (0)

Anonymous Coward | more than 6 years ago | (#20544961)


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 (5, Funny)

Anonymous Coward | more than 6 years ago | (#20545005)

A series of halogen lights mounted along the wings are illuminated at night to power the solar array.

Re:Innovative solution to the nighttime problem (2, Funny)

XaXXon (202882) | more than 6 years ago | (#20545555)

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.

What the? (2, Insightful)

veganboyjosh (896761) | more than 6 years ago | (#20545013)

enouhh


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

Re:What the? (1)

greg_barton (5551) | more than 6 years ago | (#20545055)

No furking shyte. Wish I had mod points.

Re:What the? (1)

MobileTatsu-NJG (946591) | more than 6 years ago | (#20547281)

"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?

Re:What the? (1)

coldmist (154493) | more than 6 years ago | (#20545091)

They did! They changed it from 'enuf' to 'enougg' for us.

Re:What the? (3, Informative)

cuantar (897695) | more than 6 years ago | (#20545505)

The best part is, when the story was first posted, it was "engouh" until it was corrected to read "enouhh."

Re:What the? (1)

HTH NE1 (675604) | more than 6 years ago | (#20546319)

Indeed, engouh is enouhh!

Re:What the? (1)

Kelz (611260) | more than 6 years ago | (#20545631)

I'd imagine some editors actually have a sense of humor and like to poke fun at grammar/spelling trolls.

Re:What the? (0, Troll)

MobileTatsu-NJG (946591) | more than 6 years ago | (#20546829)

"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 for one (0)

Anonymous Coward | more than 6 years ago | (#20545017)

welcome our airborne overloards as they return to their classical means of mobility.

Question? (1)

SnarfQuest (469614) | more than 6 years ago | (#20545019)

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

What if it flew in the opposite direction of sun (2, Insightful)

CrazyJim1 (809850) | more than 6 years ago | (#20545025)

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.

Re:What if it flew in the opposite direction of su (1)

Ogive17 (691899) | more than 6 years ago | (#20545573)

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.

Re:What if it flew in the opposite direction of su (1)

Loke the Dog (1054294) | more than 6 years ago | (#20545965)

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 :)

Tipping Point (2, Informative)

Doc Ruby (173196) | more than 6 years ago | (#20545313)

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.

Re:Tipping Point (3, Informative)

XaXXon (202882) | more than 6 years ago | (#20545595)

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.

Blimp (0)

Anonymous Coward | more than 6 years ago | (#20545337)

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

There's Billions waiting for something like that.

Helios was cooler (1)

iiii (541004) | more than 6 years ago | (#20545341)

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 [wikipedia.org] links [nasa.gov] .

Talk about doing it the hard way (2, Interesting)

Colin Smith (2679) | more than 6 years ago | (#20545453)

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

 

Grousing about submissions (4, Informative)

kwerle (39371) | more than 6 years ago | (#20545479)

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 [acpropulsion.com] , 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.

AC Propulsion did this a while back (3, Informative)

Thagg (9904) | more than 6 years ago | (#20546151)

Check out this press release. [acpropulsion.com]

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

Thad Beier

Re:AC Propulsion did this a while back [2yrs ago!] (1)

Thagg (9904) | more than 6 years ago | (#20546569)

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

Attaining altitude (3, Interesting)

drwho (4190) | more than 6 years ago | (#20546625)

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.
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