Around the World in a Solar Plane

Coati writes "Bertrand Piccard, the guy that flew around the world in a balloon, wants to do it again, this time in a solar plane."

solar polar

[Anonymous Coward]

how high would you need to fly at what lattitude and at what time of year to get out of earth shadow?

Why?

[Anonymous Coward]

Is there any scientific value to going around the world in a balloon, solar plane, or whatever? Or are these just things that wealthy people do to keep themselves occupied?

eco friendly?

[A1tha1us]

So after a few years of r&D half a dozen custom built protoypes (to be discarded as non-biodegradable junk) and other discarded parts they can have something that probably took more energy to make than a small town uses in a year, but then fly it around the world using only energy from the sun...I suppose it will be a cool engineering achievement.

Glider

[penguinoid]

People can stay in the air for several days in a glider. They use upward currents to gain height. You know, fly over a desert in the day, and over a forest at night.

Re:Power storage

[Zocalo]

I was wondering that too. I'd assume that the plane would essentially be a glider and would use the solar power to provide lift as required and thrust only if sufficient spare energy was available. I'd also assume any onboard batteries would be fully charged at takeoff too to give things a head start.

Even so, doing this in one hop seems a little unlikely, unless circumnavigation near the pole in summer is in order, and it's not in my book! Ignoring the tilt of the Earth, then taking off at dawn and flying west to maximise the amount of daylight would require a circumnavigation within 36 hours before night would fall. That's in the region of an average speed of 1,000mph. Fully charged batteries at takeoff, flying on battery through pre-dawn and recharging through the day and finishing off on battery at night would reduce that some, but enough for one hop?

Re:solar polar

[Theatetus]

how high would you need to fly at what lattitude and at what time of year to get out of earth shadow?

Any trig gurus please improve this for me:

Let T = radius of the earth
Let L = given angle of latitutde
Let X = "altitude" above the center of the earth to escape the earth's shadow
Let A = altitude above the earth's surface.

Now assume it is an equinox (thus the sun's rays are tangent to the earth at the poles), we want to find:

A

A = X - T since radii of a circle are equal
X = T * sec(L) X is our hypotenuse
thus
A = T * sec(L) - T
or perhaps more attractively:
T * (sec(L) - 1)

Something tells me there's a way to simplify that but I can't remember it.

For days other than an equinox, recalculate a new lattitude from the point of tangency of the Sun's rays to the earth and convert to standard lattitude

Disclaimer: this doesn't entirely work because the sun's rays are not parallel, but it should be pretty close.

Flying backwards to meet the dawn

[G4from128k]

I would assume that the pilot would fly a zigziag course. During the day, they would fly westward to stay in the sun as long as possible. During the night, they would fly eastward to meet the dawn as soon as possible.

I also wonder if they might choose a route that flies over the upwelling of air at the equatorial convergence zone. It might be rough, but those air currents could help them stay aloft during the night.

Re:Everyone asking 'can it fly at night'

[Robert Osfield]

My guess is that they will probably climb during the day and charge batteries then glide all night with a small power draw to the batteries extending the glide. If they can climb enough during the day then they might not need to use batteries, and just glide until the morning. It should be possible to build such a machine with less than 100ft/min sink rate, perhaps even 50ft/min. Thanks 3000-6000 ft lost per hour, 8 hours is 24000-48000ft height loss. Manned flight makes this more complicated though with needing oxygen and heating the pilot at high altitudes.

Remember Helios?

[adun]

NASA's little darling solar plane flew at about 90,000 feet, well above any potential cloud cover. You can assume that these guys are planning on the same strategy. But if you plan to send a manned flight up to 90k feet, doesn't that raise a whole slew of logistics questions? i.e., the amount of oxygen needed, the weight ratios to follow, etc...

Re:Get off the cross

[JaredOfEuropa]

The problem with many so-called 'ecologists' is that they frame everything in terms of 'saving the Planet'.

No, the problem with many so-called ecologists is that they frame everything in terms of threats to 'our comfortable existence'. They wrongly believe that it 'has to hurt if it's to heal', and translate every ecological problem, not just global warming but local small scale problems as well, into something that can, will and should have an enormous impact on our everyday lives. They do not believe in simple and painless solutions.

Re:TRULY A WASTE

[MrAngryForNoReason]

The point of this kind of research is to improve technology. The result is more efficient solar cells and batteries, the kind of tech which will improve thousands of things.

Its not just some guy with loads of money who thinks it would be cool to fly around the world, it is serious research into several important fields. The kind of research that without rich enthusiasts wouldn't get done.

I agree that people should be more willing to spread the wealth, which is why I applaud the "give so much a month" approach charities use, and wish more people would do it. Who would notice 10 pounds a month missing from their salary of thousands? If everyone gave an amount they could afford without even noticing then a hell of a lot of people could be helped.

Thank Burt Rutan for this;

[B5_geek]

December 1986 this was done with fuel [centennialofflight.gov]
Why can't this now be done with solar cells and high-density batteries?

I would have more faith in this project if it was being done by somebody else.

Stay aloft for weeks at a time? sure why not. Just expand on this idea [air-attack.com]

Re:Why?

[AndroidCat]

Hey, I have no problem with people trying stunts that seem crazy at the time--and dying because maybe it was crazy.

What I object to are the people that do some damned-fool stunt like travelling to the north pole by pogo-stick, then calling for help when they get snow in their boot. Suddenly a huge effort to save them is made at great expense and risk to other people. Launching a search and rescue effort shouldn't like calling the AAA. If you want to do something dangerous, do it. Or do not and die.

Re:The person in the cockpit

[rduke15]

But without a person in the cockpit, the venture won't get much media attention. And without media attention, the project won't attract much sponsorship. ..... SIGH!

Exactly.

And being the "person in the cockpit", and attracting sponsorship is what the latest Piccard seems to be good at.

And he is nicely grateful to his sponsors too. On the contacts page [solar-impulse.com] of the site, the link to his own site (www.bertrandpiccard.com) actually points to his sponsors (www.breitling.com)! Whether it is accidental, intentional, or a nice meaning-ladden lapsus is open to speculations :-)

In different times, the scientist could end up getting the media's attention, but now the work has been "Taylorized": one does the acting, and others do the real (ineteresting but not so media-flashy) work. In this case, it's the Lausanne university. In his previous achievement, it was mainly meteorologists sitting in front of boring computer screens.

Nevertheless, the project sounds exciting.