Solar Craft Flies Through Two Nights

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."

An idea

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

Re:An idea

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

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

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

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

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

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.

What the...?

engouh

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

Re:What the...?

engouh

What the hell kind of spelling mistake is that?

A typo?

more

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.

engouh solar energy

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...

Looked at your /. username lately?

Just one question...

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!

What constitutes Solar Power?

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...

Innovative solution to the nighttime problem

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

What the?

enouhh

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

Question?

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

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.

Tipping Point

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

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.

Helios was cooler

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

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

 

Grousing about submissions

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

Check out this press release. [acpropulsion.com]

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

Thad Beier

Attaining altitude

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.

Props are not counter-rotating?

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?

First 2 night Heavier than Air Craft

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.

whats with cars?

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

Re:What good is it?

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

Re:What good is it?

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

Re:lol

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

      Robotic, solar powered flying overlords?

Re:What good is it?

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?

Recon

Re:What good is it?

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?

Re:What good is it?

Surveillance package. It's gonna be made by Rockwell [rockwellcollins.com], for Rockwell [wikipedia.org].

Re:Blimp

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 [weebls-stuff.com].

Re:What good is it?

... Can this thing seriously carry any cargo that is worthwhile?

A coconut perhaps?

Re:What good is it?

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.