Solar-Powered Plane Makes Runway Debut

MikeChino writes "The much-hyped Solar Impulse airplane just completed its first runway test, paving the way for a 20-to-25-day trip around the world next year. Conceived by Bertrand Piccard, the single-pilot plane successfully used its four solar powered motors to taxi around the runway. If all goes according to plan the plane will be able to fly day and night without fuel, signaling a bright future for solar-powered flight."

Comments

What are the implications for solar races?

[Psaakyrn]

Well, a plane is just a flying car after all...

Re:What are the implications for solar races?

[AliasMarlowe]

Well, a plane is just a flying car after all...

Actually, a car is a badly designed plane. Just try driving one off a cliff, and you'll see what I mean.

Re:What are the implications for solar races?

[c6gunner]

Implications for solar car races? None. You may as well look at a sail-boat and ask "what are the implications for powerboats?". An aircraft with a large enough wing-span can stay airborne for days on end just by gliding, whereas cars tend not to move much without an engine.

Re:What are the implications for solar races?

[bandmassa]

Photo-voltaic solar is a deader end than dead dinosaur oil. While everybody runs around calling silicon the most abundant material on earth, they're forgetting that the chemicals which turn silicon from an almost perfect insulator into a photovoltaic semiconductor are some of the rarest and the solar indistries are heavily dependent on the aluminium and oil industries for these elements.

Better site?

[tjstork]

Kinda interesting they didn't have the dimensions of the solar plane readily available. From the pictures it looks like the wingspan is an easy 100 feet to carry how much, one guy? Wonder how big the wings would be to carry 200 passengers, oh, and where would get the energy to carry them at 600mph? Seems to me solar and flight are fundamentally at odds simply because you need vast surface area to get the energy to reach high speeds...but then, maybe it can work, almost like you optimize

solar powered plane energy = kw * wing area meters ^ 2 - kw * motor * mass * velocity ^ 2.
and
mass = wing density * wing area meters ^ 2

would have to factor in wind resistance from the giant wings, but that's cross sectional area, I thought, that causes drag, so if you made the wings really thin...

Re:Better site?

[nacturation]

would have to factor in wind resistance from the giant wings, but that's cross sectional area, I thought, that causes drag, so if you made the wings really thin...

If the weight ratio is too great, you could simply have two planes and suspend the pilot on a line between the wings.

Re:Better site?

[jimicus]

If the weight ratio is too great, you could simply have two planes and suspend the pilot on a line between the wings.

Probably necessary in more northern latitudes such as Europe, but in Africa I reckon one plane could easily carry the pilot.

Re:Better site?

[Anonymous Coward]

It might have a military advantage over spy satellites. If the solar plane can be made to be stealthy it could sneak in and stay around to continuously take high resolution pictures of enemy assets. Satellites can only take pictures at predictable times (that the enemy might be aware of) and another drawback is that satellites can't take continuous footage.

It could also have great scientific potential for projects where you want to watch a remote area continuously.

Re:Better site?

[tjstork]

If the weight ratio is too great, you could simply have two planes and suspend the pilot on a line between the wings.

Or you could always go with a solar powered balloon plane.

Re:Better site?

[wisdom_brewing]

the diagram in the link has the dimensions

http://news.bbc.co.uk/1/hi/sci/tech/8367214.stm

Re:Better site?

[jamesh]

suspend the pilot on a line between the wings.

What? Held under the dorsal guiding struts?

Re:Better site?

[Monolith1]

If the weight ratio is too great, you could simply have two planes and suspend the pilot on a line between the wings.

You just need some additional thrust... http://inventorspot.com/articles/solar_powered_fan_hat_wearable_gadget_looks_and_feels_cool_24822

Re:Better site?

[Simon Brooke]

Kinda interesting they didn't have the dimensions of the solar plane readily available. From the pictures it looks like the wingspan is an easy 100 feet to carry how much, one guy? Wonder how big the wings would be to carry 200 passengers, oh, and where would get the energy to carry them at 600mph? Seems to me solar and flight are fundamentally at odds simply because you need vast surface area to get the energy to reach high speeds...but then, maybe it can work, almost like you optimize

solar powered plane energy = kw * wing area meters ^ 2 - kw * motor * mass * velocity ^ 2.
and
mass = wing density * wing area meters ^ 2

would have to factor in wind resistance from the giant wings, but that's cross sectional area, I thought, that causes drag, so if you made the wings really thin...

I half agree with you. Half. None of our grandchildren are ever going to fly at 600 miles per hour. There isn't enough energy, and they won't be able to afford to use it. We're burning all the cheap energy there's ever going to be, right now. A plane which could provide practical flight at one hundred miles an hour and that they could afford to use might be useful to them. I'm sceptical, though, about whether this is the right way to go about providing that - hydrogen from electrolysis of seawater looks to me a potentially better fuel, because the amount of sunlight you can capture that way isn't limited by the wing area of the aircraft and because the fuel, even if somewhat compressed, is lighter than air and aids buoyancy.

The very high ratio of exotic materials structure to payload on this aircraft represents a lot of embodied energy in itself.

Re:Better site?

[OeLeWaPpErKe]

You'd need some place to put the solar panels, which will also put a lower limit on wing surface, because there's a minimum amount of energy you'll need.

Then due to this plane not exactly flying at 900 kph, you'd need short wings to prevent it from stalling due to the wind movement created by flying over a cow that's thinking about farting.

So you need a minimum wing surface, and you need a relatively short wing. Your only choice is going wide.

Now add to that that the maximum weight of the plane is obviously very limited (and you already have the pilot, so you add 300 pounds for safety). In essence those enormous wingspan cannot be supported by a structure that's internal to the wing, as that would add too much weight. So you have 3 cockpits : 1 manned, 2 unmanned. 3 planes "loosely" connected (some sort of elastic bands, apparently).

So you get this plane : it's really 3 planes connected to eachother at the wingtips. This is necessary due to low-speed flying and the need to collect energy. Before you ask about making a jetliner carrying 300 people solar-powered ... does it really need to be stated that's not going to happen ? It would need a wingspan of several miles, and would fly perhaps 100-150 kph.

The real reason these planes are getting built is their potential to replace satellites, and even cell towers. Once we have commercial autonomous planes that can keep flying for 10 years at, say, 15 km height we don't need satellites anymore. Furthermore, these planes would be satellites that have other advantages, like the fact that they can actually operate with an antenna gain less than 500 (no need for dishes). They would not introduce a significant delay (satellite communication low-earth-orbit adds somewhere near 300 msec transit time, geostationary ones add close to a second. Nobody, even non-gamers, like pingtimes more than a second).

And best of all : they're mobile. Can you imagine ? Some 3rd world or muslim dictator decides to grow some brains and steps down. The parliament votes to create a communications infrastructure, and asks $carrier to do so. Carrier launches 30 (or whatever number required) of these planes from a location deep within the united states, and 5 days later the entire country is covered in a completely functional cell phone network that does not require uplinks (beyond the planes themselves). The same network provides internet and television services. Whether a carrier needs to provide coverage in central manhattan or northeast pakistan, the infrastructure deployment process is identical : just build the plane. No permission (beyond countrywide flight permission that is), no pulling fiber, no renting roof space, no ...

And the military applications are equally great. Want to attack a country ? How about a permanent rocket launch basis in the sky that does not ever need to come down ?

Re:Better site?

[Anonymous Coward]

This is all technically exciting, but they'll have to find a business use for this.

it looks like the plane can carry just a few kilos of cargo, and would go around the world in around a month, not too good for transport!

Maybe it would be good for earth observation, cheaper than satellites, more detailed images.
And then maybe an unmaned version.

It will be interesting to follow

Re:Better site?

[Firethorn]

I half agree with you. Half. None of our grandchildren are ever going to fly at 600 miles per hour. There isn't enough energy, and they won't be able to afford to use it.

I disagree. If they get a serious energy crunch, they'll adjust. I don't think high speed flight is going away, it might get a tad rarer for the population, but it's not going away.

Big, mostly full planes going 600 odd mph for a couple thousand miles or more are actually very fuel efficient - especially when you're looking at overseas travel and saving weeks on a cruise liner.

They're also experimenting with bio-jet fuel, they're testing it right now for B-52s.

For the land, high speed rail, a good mesh of it with 'micro-locomotives' so you're hauling the equivalent of a plane, not 10 planes, would help. I'd want at least 120 mph, so it can compete with planes. Even then, I'm not sure about the fuel efficiency. Trains can be surprisingly inefficient, mostly due to low utilization.

Re:Better site?

[OeLeWaPpErKe]

Here's an image gallery of the plane : http://www.solvay.com/services/imagegallery/solar/airplane/0,,77566-2-0,00.htm

A more technical gallery : http://www.solvay.com/services/imagegallery/solar/technicalaspects/0,,77567-2-0,00.htm

The plane is called "solar impulse", btw, and it's Belgian.

Re:Better site?

[Anonymous Coward]

Exactly. The summary's statement that this signals a bright future for solar powered flight is way overstated. Clearly MikeChino has no idea just how much energy is required to move several hundred people or several tons of cargo around the world at several hundred MPH. One guy builds himself a one-man plane. I don't think FedEx will be interested.

Re:Better site?

[marcosdumay]

Well, you forgot that velocity = const / wing area. Now you could optimize, but don't bother, the result will just tell you to get a pair of infinitely sized wings flying at 0km/h.

Re:Better site?

[tophermeyer]

I see your point on this, but there are lots of important/cool potential applications for this that are not centered on carrying passengers.

I'm thinking surveillance aircraft capable of near continuous operation, or replacing the Goodyear blimp. You could even equip a plane like this as a cell tower, and be able to shift the hardware to cover areas with high call volume, like during a local emergency.

Right now, this tech doesn't seem capable of transporting cargo or people. However there are lots of reasons why we might want to get man-sized equipment aloft for extended periods of time.

Re:Better site?

[Anonymous Coward]

It's true that this design wouldn't work for actual commercial planes, but replace the wings with a delta wing, which has far more surface for solar panels and achieves a greater sustainment from air, thus meaning less speed required to sustain the plane.
If you also replace the batteries for better ones like the lithium-nanotube ones now under development (around 60% more energy density by replacing the cathode) and, maybe on a future solar panels with > 25% efficiency (at an affordable cost), and you have something useful.
This way it would still not be able to replace big commercial planes, but as a private plane for, let's say, 5 persons, it would be great.

I'm really impressed by the work those guys did, because as far as I've seen, solar planes have been only used by lightweight UAV's.

Re:Better site?

[elashish14]

Relax, it's just for research. They're not saying that it'll completely replace all airplane technology, or even that it will ever displace current jet fuel models - it's just something that's worthy of being looked into. Instead of asking ourselves if we can use this to fuel a jumbo jet, let's start with a simpler engineering problem and see if it's practical for powering, say, a 4-passenger private vehicle. Or maybe an unmanned drone for non-passenger purposes.

What is important about this is that if they can show that it's practical and stimulate some interest, then maybe they can get more funding and attention. That's why they have these prototype designs and demos - not cause they think it'll solve every energy-related problem the world faces. Sure, not every new, 'promising' technology ever turns out to be as great as we expect them to be; but if they weren't labeled as such, those few that actually have a chance of being viable would never receive attention.

Re:Better site?

[Idiomatick]

They don't have blimps where you come from? (I almost feel bad after how well worked your idea is... sorry)

Re:Better site?

[jimbolauski]

There's a huge market for something like this being able to launch 20 or 30 of these in a conflict area would be a great advantage. Just imagine being able to back track an insurgent's movements for 2 or 3 days because you have a whole city covered with planes. Weapons could even be carried and the only time the planes wold have to land is if they were out of ammo or needed matience these are the next evoloution in UAVs.

Re:Better site?

[clone53421]

balloon plane

Eh? I’m not sure if there is any such thing.
http://en.wikipedia.org/wiki/Inclined_plane#Blades.2C_wedges.2C_and_foils

Re:Better site?

[FreeBSD evangelist]

Kinda interesting they didn't have the dimensions of the solar plane readily available.

You didn't look very hard, did you?

TECHNCIAL DATASHEET
Wingspan: 63,40 m
Length: 21,85 m
Height: 6,40 m
Weight: 1 600 Kg
Motor power: 4 x 10 HP electric engines
Solar cells: 11 628 (10 748 on the wing, 880 on the horizontal stabilizer)
Average flying speed: 70 km/h
Take-off speed: 35 km/h
Maximum altitude: 8 500 m (27 900 ft)

http://www.solarimpulse.com/en/documents/challenge_solar.php?lang=en&group=challenge

Re:Better site?

[natehoy]

But how would the pilot grip it? By the hull?

Re:Better site?

[c6gunner]

I half agree with you. Half. None of our grandchildren are ever going to fly at 600 miles per hour. There isn't enough energy, and they won't be able to afford to use it. We're burning all the cheap energy there's ever going to be, right now.

I'm sure someone made the same argument back when horse-drawn carriages were the height of technology. Fortunately, "cheap" is a relative term. As our technology improves, things which would have been astronomically expensive - or completely impossible - a hundred years become commonplace today. The same will happen for your grandchildren. We have enough conventional oil stores to last for decades. We have enough oil sands and shales to last for centuries. Even if we just stick to conventional energy sources, we won't be running out of "cheap energy" any time soon.

until storm/nightfall/eclipse hit

[ChipMonk]

I wouldn't want to be in the middle of the Pacific Ocean when it suddenly got dark.

How well could a hybrid-energy airplane work? Would the solar cells provide more benefit in bright light than they would cost in fuel in the dark?

Re:until storm/nightfall/eclipse hit

[CyberDragon777]

RTFS!

"If all goes according to plan the plane will be able to fly day and night without fuel, signaling a bright future for solar-powered flight."

Re:until storm/nightfall/eclipse hit

[ciderVisor]

Oh yeah, all day and all of the night.

Re:until storm/nightfall/eclipse hit

[TheRaven64]

Presumably, however, it is flying on stored power during the night and charging during the day. If the sun is not present during the day then you won't be able to charge and you'll have to glide. Not a problem if you're flying over land - you just need to find a runway in the next few hours - but a big problem if you're in the middle of the ocean. That said, I'd love to have a solar powered light aircraft with a slightly bigger capacity and a shorter range. I wouldn't want to fly for more than a few hours at a time, but having something I could just park outside on an airfield and come back the next day to find it ready to fly would be great.

Re:until storm/nightfall/eclipse hit

[natehoy]

With a really good glide ratio, some of the "stored power" could be altitude. Maybe not all of it, but if you can accept a drop of 10,000 feet over the course of the night and plan on climbing back up during the day, you could reduce your need for stored power (and therefore batteries / weight) considerably. Just have enough power on tap to reduce the descent rate, not enough to actually fly level or climb during the night. And, of course, your minimum altitude should still be above the cloud deck so you have sun in the morning to do the climbing, or it has to be able to land for a quick recharge if it gets caught in the clouds.

Something like this could be useful for traffic reporting, weather observation, aerial photography, surveillance, and even communications, provided whatever onboard gear is needed is light enough and low-powered enough. It'd be a damned sight cheaper and more easily replaced than satellites, and with a considerably lower delay. "Flying Internet Access Points", anyone? (note, Internet access speeds much lower after sunset)

I'm not convinced something like this would be terribly useful for manned flight. If you want to fly, you'll get far better lift/mass ratios out of a fuel or battery than you will a solar panel. Dragging the solar panels along on the airframe will add far more weight than the amount of electricity generated in-flight could compensate for. You rapidly run into a zero-sum game of adding more panels to get more power which means more weight and surface area so you need more engine which means you need more power. Something the size of a 747 made out of thin aluminum might get 20 passengers in the air until the first breeze tears the whole thing to shreds.

However, you could use an efficient battery or Hydrogen fuel cell or something, coupled with ground-based solar collectors for charging/fueling, to make it feasible for manned round-trip flights. Flightseeing would be a great application, or recreational aviation. It could also be scaled up for larger aviation, but basically as an alternative fuel to Jet-A with an engine designed to run it.

Man...

[Anonymous Coward]

These Piccards...

Zeppelin

[seifried]

Da*nit, I want to get on a Zeppelin in say Toronto and spend 2-3 days cruising leisurely (which a nice train style sleeper-cabin, restaurant and bar, free wi-fi of course) to Europe, ideally with service running on an a day that is modified in length in order to reduce jet lag once I get there. If travel were civilized spending more time doing it would be ok. Case in point: Life lessons from an ad man.

Re:Zeppelin

[Anonymous Coward]

Yes! Yes yes yes. Or the old Frankfurt to New Jersey route. A transatlantic flight already takes up most of a day. Extend that to a few days and make it a cruise-like experience, and slap a huge array of solar panels on top to power the electric motors. If I had the expertise or money for such a project, I'd be trying to do it when I first had the idea a few years ago. As it is, I'd be glad to invest in any serious company trying to revive transatlantic airship travel.

Re:Zeppelin

[Captain Hook]

Why not just take a cruise ship? More efficent (in terms of cargo capacity) and only a bit slower than a airship would be.

Re:Zeppelin

[seifried]

Better view. And I'm not overly concerned about cargo capacity.

Re:Zeppelin

[key.aaron]

I'm afraid ocean looks like ocean from pretty much any angle...at least from lower you could make out details in the waves

Re:Zeppelin

[Idiomatick]

Zeppelin is actually a type of airship... And the original designers are still in existence... making airships. Feel free to invest...

Re:Zeppelin

[TheRaven64]

Cruise ships usually travel at about 20kts. The large dirigibles currently being built go at around 45kts. Over a distance of around 3300 nautical miles, the travel time for a dirigible would be around 3 days, while a cruise ship would take almost 7.

Re:Zeppelin

[Anonymous Coward]

Energy consumption on a cruise ship is a lot more demanding than a Zepplin.

free fueled planes exist?

[alienzed]

So can we get our flying cars already?

Re:free fueled planes exist?

[mcgrew]

Sure! Here are a few photos....
http://www.shatterhand007.com/ChristopherLee/LEECarStunt.jpg
http://www.spankyspangler.com/pics/spanky_RandyHill_car_jump_crash01.JPG
http://www.cgfocus.com/gal_images/axis3d/CarJump_674a66af7a57589bdfbe689b51a95a41.jpg
http://www.spareroom.co.nz/wp-content/uploads/2008/08/hoon_footage.jpg
http://www.focol.org/kahs/images/Clippings/PC-Car_going_off_cliff.jpg
http://lightsideoflife.files.wordpress.com/2009/04/car-flying-off-cliff.jpg

NASA already has a Solar UAV

[BikeHelmet]

http://www.youtube.com/watch?v=5oNHD41MLMk

But a manned plane would be pretty neat. Hope it has enough batteries for the night - the solar UAV does a lot of gliding, which might not be possible with a heavier aircraft actually attempting to get somewhere.

Re:NASA already has a Solar UAV

[MichaelSmith]

Maybe it has pedals.

Re:NASA already has a Solar UAV

[Goffee71]

oh, big planes can glide a loooong way - http://en.wikipedia.org/wiki/British_Airways_Flight_9

Re:NASA already has a Solar UAV

[C0vardeAn0nim0]

that flight crew managed to restart the engines and made a powered landing in jakarta.

for a gliding landing all the way through, check air canada flight 143, AKA, gimli glider

Re:NASA already has a Solar UAV

[elashish14]

I'm not just worried about the night, but I'm also wondering how direct the sunlight has to be, because this could narrow which air routes can be used. Will it only work at direct, perpendicular incidence? Is there a range of angles where it would be enough? Or do the panels themselves have trackers to orient themselves towards the light?

I assume that they're not huge issues cause they can make it through the night on battery, but they're interesting to consider. Also, I wonder how long it takes those batteries to fully charge.

Re:NASA already has a Solar UAV

[necro81]

Thanks to you, I have now learned a lot more than most people should about commercial jetliners losing all power. Great work!

Re:NASA already has a Solar UAV

[caseih]

A better example is Air Transat Flight 236 where an Airbus 330 glided about 100 miles to a landing.

http://en.wikipedia.org/wiki/Air_Transat_Flight_236

Re:NASA already has a Solar UAV

[cranq]

Sometimes aircraft just run out of fuel. http://en.wikipedia.org/wiki/Gimli_Glider

Re:NASA already has a Solar UAV

[Sulphur]

Some sailplanes carry water in the wings to weigh the plane down. The effect is to speed it up without changing the glide slope ( so I'm told ).

Solar Powered plane becomes

[lul_wat]

Solar Powered plane becomes Solar Powered Car! Film at 11.

Commas

[MichaelSmith]

Interesting that on their web site the wingspan is 63,40 m but mass is 1 600 Kg. I suppose they can afford less confusion with the mass of their aircraft.

Re:Commas

[Marcika]

The decimal comma is an SI standard as much as the decimal point and its usage is preferred (according to Wikipedia) in Germany, France, Belgium, Denmark, Italy, Serbia, Croatia, Bosnia, Estonia, Finland, Hungary, Poland, Czech Republic, Slovakia, French Canada, Romania, Sweden and much of the rest of Europe.

Have a look where the design team and the sponsors come from.

Re:Commas

[Zouden]

The rationale is that a speck of ink (or other unwanted mark) is less likely to be confused for a comma than it is for a point.

Since the thousands separator is merely decoration, it doesn't matter if you mistake a speck of ink for one. But the decimal separator is crucial, so it should be as unambiguous as possible.

A comma is also bigger than a point, so it's easier to read for people with poor eyesight. It makes the difference between a 1,5ml dose of a drug and a 15ml dose.

Re:Commas

[Anonymous Coward]

A comma is also bigger than a point, so it's easier to read for people with poor eyesight. It makes the difference between a 1,5ml dose of a drug and a 15ml dose.

Yet somehow we have managed to survive.

Re:Commas

[MichaelSmith]

Yes I realised my mistake about one ohnosecond after I posted that.

Re:Commas

[hellop2]

Yes, but yelling "One comma two one jiggawatts!" just doesn't pack the same punch.

Re:Commas

[clone53421]

If it’s due to poor eyesight, yes. The people delivering medical service should have the eyesight, precision, and attentiveness to tell the difference between 1.5 ml and 15 ml.

If it’s due to poor handwriting or difficult-to-read print, though, I can see how this would be a legitimate issue and it couldn’t always just be blamed on the medical professional who’s doing the job.

tl;dr: Parent has a point, but oversimplifies the issue. I don’t think “Troll” is warranted.

Re:Commas

[cvd6262]

The decimal comma is an SI standard as much as the decimal point and its usage is preferred (according to Wikipedia) in Germany, France, Belgium, Denmark, Italy, Serbia, Croatia, Bosnia, Estonia, Finland, Hungary, Poland, Czech Republic, Slovakia, French Canada, Romania, Sweden and much of the rest of Europe.

I was in the Louvre looking at the old French crown jewels when I heard someone read the display: "Fifty-four THOUSAND carats!?!?! WOW!"

Re:Commas

[DNS-and-BIND]

The regular decimal is an SI standard and its usage is preferred in China, India, Russia, America, Canada (the unimportant, non-French part), Mexico, all of South America, Africa, Australia, New Zealand...my fingers are getting tired. But hey, you've got Finland *and* Estonia on your standard. Good show!

You'd figure the holier-than-thou would be the ones to find out what the world's standard was and slavishly adhere to it, proclaiming all the while how superior it is, and how anyone who clings to an outdated system out of convenience or custom is a total moron. I can tell you firsthand the Chinese are baffled when it comes to decimals and commas being the wrong way around.

Re:Commas

[metlin]

You mean like how we Americans adhere to the metric standard? :-)

Wow, that's a good news!

[Wege]

we definitely need more and more of that kind of solutions, not sure though if such solar planes will make it info mainstream

Re:Wow, that's a good news!

[Monolith1]

Good its got a second engine, to take you to the crash site.

Yeah.. we live in the future..

[cpscotti]

Combine this with the predator and we are soo.... soo.. **

NASA USED TO have a Solar UAV

[Yvanhoe]

It crashed in 2003 in the Pacific Ocean :

http://en.wikipedia.org/wiki/File:Pages_from_64317main_helios-3.jpg

Unexplainably, it stopped the project. I still wonder why.

I read "Plane Makes RunAway Debut "

[Qcaze]

.. and my brain made these funny images of a runaway plane not quite ready for commitment..

Re:I read "Plane Makes RunAway Debut "

[Anonymous Coward]

My brain made a fynny image of a transformer(Starscream?) doing it first catwalk.

...those Picards!!!!

[master_p]

...always on the forefront of exploration!!! ;-)

Insightfull my ass

[SmallFurryCreature]

This guy isn't insightful, he is a twit.

Not all planes are passenger planes. This plane would be perfect for unmanned or long range observation. Carrying all your fuel aboard becomes incredibly expensive the longer your range has to be. This plane solves that by refueling constantly while inflight.

Insightful? No, short-sighted, yes.

Let's do the math on this one... how many HP?

[Ancient_Hacker]

Let's do the math.

61 meters wingspan, as an estimate, let's say 6 meters width. That's 360, let's say 400 square meters counting the tail surfaces.
At 15% efficiency and no clouds at high noon , that's about 60 kilowatts, say almost 100 horses. But if you subtract for unavoidable factors
like non high-noon, clouds, battery chemistry, and night, say 40% x 70% x 75% x 40%, we're down to about TWELVE average horsepower trying to lift 3500 pounds.
By comparison, your basic very fragile ultra-light plane that can barely get off the ground has like ten times that power to weight ratio.

This thing is not gonna fly, figuratively or literally.

Re:Let's do the math on this one... how many HP?

[ThosLives]

Well, this solar plane isn't so much a plane as it is a motor glider given the wingspan and aspect ratio. The motor is just enough to get it off the ground and help gain altitude when thermals and other updraft conditions are not present. Gliders seem to fly just fine and they have a zero power-to-weight ratio, so that argument is a bit naive. Gliders can also be fairly fast given the right conditions: there are high-performance glider races where the gliders fly around 200 knots over a course of about 180 nautical miles (although I wouldn't say the particular aircraft in this article would be a "high performance" aircraft).

Re:Let's do the math on this one... how many HP?

[fnj]

Yeah, right, chief, they are idiots and you are real smart. Did you ever hear about a thing called lift to drag ratio? An enormous, extremely high aspect ratio wing has a lift to drag ratio that is out of sight. And power necessary to overcome parasitic drag is proportional to the cube of the speed. This thing flies at a hair over 20 mph near the surface and peaks at about 45 mph at high altitude where the lower air density cuts the drag.

Oh, and if you don't want clouds in the way you, like, fly over them, ya know?

Common ultralights are ridiculously inefficient, aerodynamically, because they don't NEED to be any better to perform their mission.

Re:Let's do the math on this one... how many HP?

[Idiomatick]

http://en.wikipedia.org/wiki/Solar_plane

all the people that have done it in past must be cheating.

Re:Let's do the math on this one... how many HP?

[Ancient_Hacker]

L/D has nothing to do with it.

Do the math-- 3500 pounds and 12 horsepower -- what's going to be the absolute best rate of climb possible with no friction---? under 100 FPM.

Add a little unavoidable drag and you have a really miserable flying machine.

Also if it takes off at 20MPH, then that implies it can't take off if the wind is more than 6MPH or so in any direction.

A miserable and very dangerous flying machine.

Re:Let's do the math on this one... how many HP?

[Ancient_Hacker]

Perhaps you should consider the difference between a plane that can briefly just barely get off the ground, under optimal sun and wind conditions, carrying no usable payload, versus a plane that can takeoff safely in average or marginal weather, and stay up and get somewhere say against a mild wind, and climb at more than 100FPM, and not stall with a mild tail or crosswind, or breakup in turbulence, and carry a useful payload, perhaps even be human-rated, and do so economically, year after year.
 

Re:Let's do the math on this one... how many HP?

[uuddlrlrab]

Because, as we all know, flight has nothing to do with lift and drag, amirite?

What I really don't get is why you continue to try to apply the dynamics of a plane to something that is obviously not one. This is essentially a solar powered glider. 'Nuff said.

Re:Let's do the math on this one... how many HP?

[Anonymous Coward]

Sigh. Think. Conservation of energy. To lift 3500 pounds takes energy. L/D is not relevant. No matter what the L/D, energy has to be expended to lift 3500 pounds to altitude. Even with an infinite L/D ratio. One horsepower lifts 550 pounds one foot per second. ( Pardon the old-style units. ) Assuming NO drag, infinite L/D, 100% propeller efficiency, no wind, no crosswind, no downdrafts, perfect balance, 12 horses can only lift 3500 pounds 1.88 feet per second. Nuff said.

Paul MacCready already built a couple of those

[NotSoHeavyD3]

This one http://en.wikipedia.org/wiki/Solar_Challenger plus he was involved with the NASA one http://en.wikipedia.org/wiki/Helios_Prototype. http://en.wikipedia.org/wiki/Paul_B._MacCready Hmm, looks like he died a few years ago. (Note corelation =/= causation. His working on a solar plane probably had nothing to do with his death.)

Anyone else notice...

[smitty777]

...that they're taking off on a cloudy day on the video? Maybe that's why it was only a runway test ;^)

Comma-separated values

[tepples]

But the decimal separator is crucial, so it should be as unambiguous as possible.

But with the rise of the spreadsheet, something else became ambiguous: decimal separator vs. the field separator in CSV files. (I prefer tabs, but some of our service providers prefer commas; it's a good thing I live in Anglophonia.)

Re:Comma-separated values

[clone53421]

Use quoted fields to hold numbers if they use the comma as the decimal separator. It’s no different from having “Last, First” fields.

Re:Comma-separated values

[TheRaven64]

Some CSV parsers will treat quoted inputs as text, not as numbers.

Re:Comma-separated values

[clone53421]

Then I’m betting they’d also consider the dot to be the decimal separator. If they’re correctly written, it will still be displayed using the regional settings for numbers, although that’s more of a crap-shoot.

night and day?

[physburn]

Just how does it get power at night? Presummably on a clouded day, it can get power once it get above the clouds, but its batteries can't be good for very long in the advent of lose of sun light. Planes really need a constraited power source, and until wehttp://www.feeddistiller.com/blogs/Hydrogen%20Power/feed.html can do better than chemical, fuel cells or combustion seem best to me. For power/weight ratio, hydrogen powered planes, must be best, with methane or boranes beating all the other hydrogen carbons. The weight of the cryogenic storage, might be a problem though.

---

Hydrogen Power Feed @ Feed Distiller

Re:night and day?

[drinkypoo]

Commercial fuel cells have been ten years away for more than ten years, they're in the same category as supercapacitors, show me the fucking product. Hydrogen has crap energy density and it would make more sense to just use biodiesel in current turbine designs than to ever move to hydrogen; turbines are wicked efficient, and making biodiesel is more efficient than cracking hydrogen by any means we now have available. In fact, most of the nation's hydrogen is cracked from Natural Gas, making it a petro-fuel like all the rest. In the future it will still be necessary to produce the hydrogen we need, since there's no hydrogen mines.

Or, short form, hydrogen will never be more than a small part of the answer.

Re:night and day?

[Guysmiley777]

Hydrogen is an energy transmission device, it's never been a SOURCE of energy. We can't "mine" hydrogen or produce it out of nothing.

You could make the argument that hydrogen electrolysis would work for solar or wind farms to store generated energy, but I have no idea how efficient that would be. I'd imagine it would need to be on a very large scale to be worth it.

Re:night and day?

[drinkypoo]

Hydrogen is an energy transmission device, it's never been a SOURCE of energy. We can't "mine" hydrogen or produce it out of nothing.

Uh, yeah, that's what I said, asshole. We lose around 5% of our electrical power in transmission in this country (including conversion related to transmission.) The efficiency of hydrogen through electrolysis is under 60% in basically all real-world cases. Can you see why Hydrogen is fucking stupid, given that it is prohibitively expensive (in terms of energy cost) to make, and that the other forms of hydrogen ARE in effect mined, since again we make most of it from Natural Gas? Which, BTW, comes from wells, we don't make it. We crack the hydrogen out of natural gas in conceptually much the same way we crack the useful hydrocarbons from crude before we burn them in our cars.

You could make the argument that hydrogen electrolysis would work for solar or wind farms to store generated energy, but I have no idea how efficient that would be. I'd imagine it would need to be on a very large scale to be worth it.

Maglev-bearing flywheels are cheaper to build, easier to contain (bury them) and more efficient to store power in. Hydrogen is a boondoggle looking for justification. The only case I can think of where it would actually be useful is in fork lifts, where it would be even cleaner than running them on propane. The problem there is that flywheels need a lot of counterweight and as such are perfect candidates for counterrotating flywheels, which can be spun up rapidly with a variety of technologies.

Re:night and day?

[icebrain]

Actually, hydrogen has very good energy density by mass (the best of any chemical fuel). By volume, it's very poor. That's why you see hydrogen used as a fuel for rockets (where mass matters much more than volume), but not aircraft. A commercial airliner running on hydrogen would require a huge insulated tank that would add lots of weight and drag; you can't just tuck the fuel into the wings like you can with jet-A. It may become usable for small aircraft, but I don't think you'll see it used for anything larger (except maybe super-high-altitude UAVs and exotic hypersonic vehicles).

However, I do agree that biomass-based synthetic fuels will be far more prevalent in the future. Assuming we don't try to force the use of inefficient food crops for production through heavy-handed government and lobbyist actions (coughcorncough), and instead focus on using mroe efficient plants, algae, and leftover/waste biomass, it will likely work out. I know that there are already a few promising replacements for piston-engine avgas and diesel and jet fuel under development, and I think such things are a far better investment of funds for several reasons. They are essentially carbon-neutral once applied on a large scale, they eliminate strategic and economic dependence on politically volatile nation-state cartel members, and they are essentially "drop-in" replacements for current fuels, allowing current infrastructure to be used and changed over much more cheaply than drastic changes.

Re:night and day?

[FreeBSD evangelist]

So none of you guys actually read TFA, did you?

The whole point of this exercise is to build a plane that =can= fly through the night. It does this by storing energy accumulated during the day, both in batteries (chemical) and as altitude (kinetic). Climb during the day, descend (slowly) at night. It's designed to fly at 20 to 30 thousand feet, so clouds aren't an issue. It has four 10 HP electric motors, which will average 8 HP each during flight. It flies at around 40 MPH.

Re:night and day?

[Guysmiley777]

Uh, forget to take your fucking medications today, dipshit? Fuck you and the horse you rode in on.

I never said hydrogen was the best solution to ANYTHING, only pointed out that cracking it from hydrocarbons isn't the only place it could be obtained.

Maglev flywheels? Hydrogen is an unmitigated boondoggle and you're talking about maglev flywheels? Did you manage to find a high temperature superconductor bearing, or do you want a cryogenics plant to go with your magic pink unicorn? To quote from an internet jackass, "show me the fucking product".

Re:night and day?

[drinkypoo]

Maglev flywheels? Hydrogen is an unmitigated boondoggle and you're talking about maglev flywheels? Did you manage to find a high temperature superconductor bearing,

You are a big fucking idiot who should stop now while he is behind

Tech is not here.

[Shivetya]

You left out one important part of your 200 passenger plane. Strength of materials to enable any reasonable speeds. I would be curious just how calm of air this solar plane needs to get airborne and stay there without being being damaged. Then there is the whole issue of flying for that many days and not encountering turbulent weather.

Planes already use exotic materials to weigh as little as financially reasons allow. While this solar plane is a neat concept its nothing more than that. I was more interested in human powered flight across the channel.

Old story

[mcgrew]

Sunrise
The 27 lb (12 kg) unmanned AstroFlight Sunrise, the result of an ARPA contract, made the world's first solar-powered flight from Bicycle Lake, a dry lakebed on the Fort Irwin Military Reservation, on 4 November 1974. The improved Sunrise II flew on 27 September 1975 at Nellis AFB.[3][4][5]

Sunseeker
In 1990 the solar powered airplane Sunseeker successfully flew across the USA, piloted by Eric Raymond.[9] It used a small battery charged by solar cells on the wing to drive a propeller for takeoff, and then flew on direct solar power and took advantage of soaring conditions when possible.[10]

The Sunseeker II, built in 2002, was updated in 2005-2006 with a more powerful motor, larger wing, lithium battery packs and updated control electronics.[11] As of Dec, 2008 it was the only manned solar powered airplane in flying condition and is operated regularly by Solar Flight.[10] In 2009 it became the first solar-powered aircraft to cross the Alps, 99 years after the first crossing of the Alps by an aircraft.[12]

The tech been in development for a while now...

Good News

[rssrss]

No Red Eyes.

Re:What are the implications for solar races?shoes

[Anonymous Coward]

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on a related note...

[Anonymous Coward]

today, the first solar power aircraft crashed during take off as the sun became temporarily obscured by cloud cover.

dude, wind turbine?

[Anonymous Coward]

why dont they just put a wind turbine on that thing, that would work so much better.

Re:What are the implications for solar races?shoes

[ais523]

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Re:What are the implications for solar races?shoes

[Anonymous Coward]

Drat. And it seemed like such a good idea.

Maybe if the replies get modded up...

It's really about advancing solar technology.

[Tyerin]

Great, it's a plane that can fly using solar power. Due to it's current design, in itself is it very useful? Maybe recreationally. Commercially? Naw. However it does open the path for better solar technolgies, including for cars, homes and other devices. If all goes well it proves that solar technology can be a very viable and renewable resource that's worth investing in, even if it never makes it to huge commercial planes (That might not always be the main method of travel at large distances down the road anyway, seen the rate technology increases.) Power is already fairly cheap, in north america anyway; but soon we could have such an abundance that we no longer pay for electricity (Monthly anyway). As solar panels becomes cheaper and more widely used as they become more effective, we could see alot more people off grid, until it becomes a design standard for houses not to require grid power except during excessive lack of sunlight, or even just to reduce the power load on our not so renewable sources of power. These people right here are at the heart of this advancement. I hope the best for this as twenty years ago even the idea would be completly scoffed at. You want me to invest in a plane that can fly just off of light from our sun....

My idea is the best idea. Trust me.

[anticharisma]

Here is my design: http://www.anticharisma.com/zeplinaeroplane.html It is a better idea than anything I've seen the big boys come up with. If only they'd listen to me huh?

Re:My idea is the best idea. Trust me.

[anticharisma]

If we make simple safe cheap aircraft then we eliminate the bad things that detract from the freedom that aviation should offer to humanity.

Is this a "Historical Document"?

[Eclipse-now]

Impulse power? Piccard? Surely I'm dreaming: next they'll be using subspace arrays to communicate with the thing!!! I'd had a rather strong Gin & Tonic or 2, but I had the impression "Galaxy Quest" was just a comedy... don't tell me G&T disguised the fact that is was a genuine "historical document" after all?

Oh well, look on the bright side! If my great-great-great-great grandchildren serve in Starfleet, at least one of them will have a high probability of seeing Kirk getting his shirt torn off. Be still my beating heart!

Easy to shoot down.

[tjstork]

And the military applications are equally great. Want to attack a country ? How about a permanent rocket launch basis in the sky that does not ever need to come down ?

Have you noticed that powerful lasers are becoming cheaper and easier all the time, that radars are getting better and better all the time? We're getting to a point where anyone with a few grand will be able to shoot down one of these robot chumpies, and why the hell not, they are robots, and noone gave anyone permission for them to spy on me.

That's my answer to spy planes hovering over us.

KILL EVERY ONE OF THEM.

If you want to make them be both really big and really slow and have them go in long slow and predictable circles, hey so much the better.

Re:Easy to shoot down.

[OeLeWaPpErKe]

Have you ever tried finding a small plane 50 meters overhead ? Either with your own eyes, or with a camera ? With your own eyes, if the plane is quiet (the IDF's UAVs sound like lawnmowers. They're all but invisible, but you sure hear them. If the sound were to be fixed, they're almost totally undetectable. And at night, they're invisible at 5 meters height too). Finding these things is hopeless.

About radars, even with very modern technology, it's extremely hard. Due to perspective issues with planes flying at that altitude, they're basically invulnerable. Ground-based radars can get "lucky" if the plane is right above them, but even then it'll only be a short while.

The only real way to detect these down is from an AWACS-type craft, flying at at least several kilometers high. Not something every John and Harry have in their garage. Also it would be a LOT easier for the UAV's to attack the AWACS than the reverse (an AWACS can be escorted by planes that have 24 rockets at best. Therefore sending 50 UAV's at them is a sure kill).

And obviously, radars only detect metals effectively and reliably. They have issues finding composite materials, or even in metal general structures that are smaller than their (generally quite long wavelength. If the guidance computer + engine were to be 10 cubic cm, another 10 cubic cm battery and that's the only metal inside, they'd be invisible to even very advanced radars at 100 meters or so.

Camera detection would work, but it'd require cameras of several hundred megapixels, positioned on a normal-altitude aircraft. Not exactly the kind of technology you'd expect to see under this year's Christmas tree. Again, a fleet of UAV's could probably choose to attack the (very easy to locate, because it's huge) awacs.

And you could get the same problem Israel has. HOW will you shoot these planes down ? If these planes cost $100 a piece (they're tiny, not much processing power, not much materials), firing a $100.000 sidewinder rocket at them is suicide, due to economics, even for a country with the financial resources of America. Also, at that tiny altitude, there are large risks involved : the rocket could easily mistake a telephone pole, a bird, even a kid's ball or some such for it's target.

And even if you do shoot them down, the result of a very high speed mid-air explosive collision will be a fireball crashing on the ground, potentially in the middle of a city, at very high speeds. Potentially in a kindergarten, or some other politically very undesirable location.

I doubt that there will be an answer to these weapons, except perhaps making sure you have more of them than the enemy does.

Re:Easy to shoot down.

[tjstork]

Have you ever tried finding a small plane 50 meters overhead

Dude, its more than that. 50,000 feet up is 10 miles away. You cannot see or even hear even a pretty big jet at that altitude.

Maybe to distinguish from multiplication?

[Gaffod]

I'm not sure about that, multiplying decimals seems the most obvious problem to me although that may also be a factor (cha-ching!). "6,02.10^23" is perfectly unambiguous while "6.02-" well, you get the point (Har har). There's some crazy folks who do "6.02×10^23" or "6.02*10^23". Those look sort of lame to me among properly formatted calculations, though. That said I wouldn't mind if everyone switched to the asterisk as the primary multiplication symbol, because hey, why not?