The Solar Impulse in its final version is designed to have a wingspan of about 80m (i.e. equal to the wingspan of an A380) while its take-off weight should be 2ton or less (the A380 by comparison with the ability to carry 550 passengers has a take-off weight of 560ton). Oh, and given the low power availability from the sun (about 12PS or equal to the Kitty Hawk Wright Brothers first machine) constrains the take-off speed to 45mph and a max air speed at 39.000ft altitude to about 80mph.

Making that long and thin wing is really amazing yet I would not want to go close to bad turbulence riding on it :-)

Orthodoxy is not a religion.