This is exciting news, scientifically. I'm curious what practical applications there are. I can think of a few, but I'm sure it's not exhaustive

• Cheap, quick-to-setup communications relay (mobile cell tower with its own satellite uplink to reduce costs of on-the-ground devices?)

• Non-military surveillance (I assume it would be easy prey for anti-aircraft weaponry, but would probably be quite useful for constant surveying of disaster sites, for example)

• Small datacenter that is easy to keep out of any nation's jurisdiction (a few large hard drives and another satellite uplink, and just keep it circling over the Atlantic)

• Long-term airborne advertising (is it powerful enough to tow an old-school banner?)

It is airborne advertising, the project was sponsored by OMEGA. That's their logo on the side, and they're already selling Solar Impulse watches :-)

http://www.omegawatches.com/spirit/pioneering/solar-impulse

That's the kind of advertising I would like to see more companies put money towards.

Doesn't it kind of imply that we will see heavy spamming of the sky in the future? I guess by now there are already zeppelins used for advertising, but perhaps they were not efficient enough?

I was thinking more about Omega sponsoring the research & stuff.

It's a win-win. OMEGA's brand values are all about it being the watch of choice for pioneers and explorers. This is a great way to reinforce their brand in an authentic way. What's Rolex doing, golf tournaments?

I kind of thought watches are dead. But granted, if you are an explorer, you might not have the opportunity to charge your iPhone, so a watch might be of use.

And of course there are deep sea divers, which still rely on mechanic (aut-windup) watches. Mostly Rolex.

There's a reason for that: If you dive in 60 metres depth, or deeper and your dive computer -, or watch battery conks out you're dead.

I don't think anyone in OMEGA's target market believes watches are dead. Maybe Casio and Timex need to worry.

And of course, an automatic movement never runs out of power as long as you're wearing it.

And tennis.

In tennis now Rolex has been completely eclipsed by Richard Mille, which I'd guess most people hadn't even heard of until Rafael Nadal started wearing one. Their brand is really taking a beating now, it can't be helped by Wiley writing songs about it. Be interesting to see what they do to dig themselves out of this hole.

Nope. That is incredibly expensive way to advertise.

> I'm curious what practical applications there are

None. It's totally pointless actually.

Very cool, but pointless.

All those solar cells and batteries cost more than just fueling it with regular fuel, and leaving the solar cells on the ground to power other things.

> Cheap, quick-to-setup communications relay > Small datacenter > Long-term airborne

Not cheap at all, and a blimp (zeppelin) would do a much better job for all of those.

(The batteries alone cost more than $20,000, and the solar cells probably in the $100,000 range, and the carbon fiber around $50,000 for the raw materials. I would estimate half a million each if mass produced.)

It might possibly be interesting for continuous surveillance, if you have no ground station where you can land. (But it flies so slow (43 mph) that it would take a very very long time to get anywhere.)

For regular constant surveying it's cheaper to have two planes and use them in relays.

I'm all for reducing hydrocarbon usage, but lets reduce it for fixed installations, and save the hydrocarbons for the mobile ones (planes, cars).

If you look at the specs http://en.wikipedia.org/wiki/HB-SIA it can just barely fly, it's not even strong enough to hold two people.

LOL! I suppose you would say the Wright Brothers were wasting their time, "it's not even strong enough to hold two people" indeed!

All exciting new technologies start out too feeble for practical use, just like human babies...

Not exactly.

They said:

"Once improved battery efficiency makes it possible to reduce the weight, a two-seater is envisaged to make a non-stop circumnavigation."

Uh hu. We've been waiting for improved battery technology for decades. This is cool, but utterly impractical. Solar power plus batteries simply are not physically capable of doing a better job.

They are going for high profile, but low impact projects.

High profile - what's cooler than a perpetual plane? But low impact - if they actually wanted to help reduce hydrocarbon usage this is not good way to do it.

I totally see the coolness. But my response was about the practicality.

But battery technology is improving and that should be easy to prove: these weren't lead-acid batteries after all.

I'm thinking the best application would be maritime surveillance. It takes a long time to get to the loiter zone, but once it's there it can circle indefinitely (I'm assuming it can be made unmanned). If you're ~1000 miles from the nearest airbase that's probably a lot cheaper than swapping planes out every N hours, and the $0.5 million cost is virtually nothing on a military budget.

I can't think of any good civilian uses, though.

not only navies use oceans - there are magnitude more commercial vessels that are currently forced to either use very unreliable low bandwidth or very expensive satellite communications.

I was suggesting it for surveillance, like the detection of smugglers, illegal fishing, et cetera. I can't imagine that it would be in any way cheaper than satellite communications if all you need is a communications relay.

> mobile cell tower with its own satellite uplink to reduce costs of on-the-ground devices

There is growing suspicion that microwave radiation from cell phone towers is having negative biological effects on nearby wildlife. The sooner we have the option to cheaply put these things up in the air, the better.

You wouldn't want to use it for any of that - a balloon would be better for the two first, since you want it stay stationary over the area that you want to cover, for the second you also want a balloon as you again want it stay stationary over the target.

The third point doesn't get you anything, the middle of the Atlantic is technically not part of any duristriction, but the plane it self would fall under the duristriction of whatever countrys flag it flew.

As for the last point, a Zeppelin would be better and it would be trivial to power that by batteries (or even just solar cells and simply let it turn of the engines at night or when there is really bad weather).

except balloon/zeppelin won't stay stationary or it will need magnitude more energy to maneuver!

I am not sure about the magniture more energy - after all the neither the zeppelin nor the balloon would need the energy to stay afloat, only to maneuver.

But there is a much easier solution to your problem, and it is called an anchor.

Bertrand Piccard, who is leading this project, comes from a family of explorers (e.g. he was also the first to travel non-stop around the world in a hot-air balloon). He also gave a pretty interesting TED talk (starting with ballooning as a metaphor for life, then moving on the solar airplane project):

http://www.ted.com/talks/bertrand_piccard_s_solar_powered_ad...

Why don't they make a solar-powered airship? That's more practical. Airship requires less energy to stay up and navigate, and has greater surface area to receive sun light.

Airships are already capable of staying in the air for days at a time. But they're so expensive to operate that they're no good for most of the possible applications of this thing.

Curious, why are they expensive to operate?

How about building a hybrid of airship and plane? Make it more maneuverable than airship with the extra power from solar energy and staying up longer than a plane. It's possible for a robotic hybrid airship to stay up for months and years. Rest floating to suck up solar power when it runs low on energy, then move on when the power is charged up. If it caught up in a gulf stream, just let it ride out the stream to go around the Globe.

It would be interesting to see these Solar Birds floating in the sky. (Ha, I even got the name for them. Someone grabs some funding quick to get it going.)

First, not very easy to put a lot of usable solar panels onto airship, but it requires WAY more energy than a glider to maneuver due to ENORMOUS size. Sure, solar airship may have it's applications too.

Second, it's not very exciting to fly around the world in airship if you already did it in a balloon.

I have to say, I am not impressed with the article... "Perpetual Flight?" I say yes you can probably fly this airplane forever until a motor breaks or something BUT there is a big difference between a single pilot airplane that takes a team of people to ensure it does not have the wings scratched and a commercial airliner that runs on solar. While the airliner is awesome if we can pull it off, I would not be surprised if we were 20-50 years away from that.

I'm not sure why "Perpetual Flight" would have anything to do with airliners - typically you would prefer to land those fairly often. This would never need to land, signifying to me that it would be useful as an automated drone of some sort, possibly a cheaper alternative to a geosynchronous satellite.

You would never need to refuel. You could set down anywhere there was a runway. That massively lowers the barriers to entry of "being an airport".

But what about a battlefield surveillance drone that can loiter for months?

Or a flying antennae that can provide GSM/Wifi/etc over a festival or disaster site at a few hours notice?