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."

Comments

Everyone asking 'can it fly at night'

[hookedup]

If you had clicked the article link, you'd see a picture of it flying at dusk, right on the front page!.

Also from the press release

The Solar Impulse aircraft will have an extremely long wingspan, advanced aerodynamics, and a revolutionary structure in order to capture and store sufficient solar energy during the day and to be able to maintain itself in flight during the night.

Re:Power storage

[Coelacanth]

An aircraft of this type will certainly be cruising above the clouds, and will be steering well clear of any convective activity (thunderstorms) for safety reasons. The real power storage challenge is to get through the night.

This is the reason you don't see all that many solar-powered UAVs, never mind piloted aircraft. The economics of solar flight would change radically if battery technology improved.

Re:Sunny skies

[isorox]

You need to make 700mph to fly arround the world in complete sunlight, starting at sunrise on the equator, and taking 36 hours arriving at your departure point at sunset the next day.

Re:No, the son of Jacques & grand-son of Augus

[rduke15]

Who is Jean-Luc Piccard anyway?

Bertrand is the son of Jacques and the grand-son of Auguste. See his biography.

"His grandfather, Auguste (1884-1962), [...invented] the principle of the pressurised cockpit and the stratospheric balloon. In making the first exploration of the stratosphere [...] in 1931, he [...] became the first man to see the curvature of the earth's surface with his own eyes."

"His father, Jacques, continued the work of Auguste [...] the world's deepest dive (-10916 metres in the Marianas Trench, the greatest known ocean depth)."

A better link, explaining the technology

[rduke15]

The EPFL explains much more about the technological aspects. It's in French of course: here.

But for those who cannot read :-), they also have nice pictures

One technological aspect is that by flying very high, they can take advantage of the cold (-55C), which can improve efficiency of electro-magnetic motors.

There are other interesting bits. I guess the page will be translated in English in a few days. (Forget computer translations, unless you want a cheap laugh)

Re:Sunny skies

[swillden]

As long as he can design a solar plane which can fly at mach 2, this shouldn't be a problem.

Nahh, 700 mph is all he needs. If he flies with the sun, night will gain on him at a velocity of v_s - v, where v_s is the speed of the light's edge and v is his speed. If he takes off at dawn, and flies along the equator, he has to get all the way around (25,000 miles) before night, which starts out at 12,500 miles away, catches up.

So, he has to achieve a velocity v that satisfies both:

(v_s - v) t = c/2

and

v t = c

where t is the travel time and c is the circumference of the earth. Isolating t in each and setting them equal gives:

c / [ 2 (v_s - v) ] = c / v
==> 2 (v_s - v) = v
==> 2 v_s = 3 v
==> v = 2/3 v_s

Plugging in the numbers, that means he needs a velocity of about 694 mph, assuming the earth's circumference is 25000 miles.