A Solar Plane

Lightweight plane (31kg/ 68lb) is launched by hand

Flies autonomously and can climb to more than 18,000m (58,000ft)

By day it flies on solar power and recharges batteries.

By night it is powered by rechargeable lithium-sulphur batteries

Wow, why I like comments. I get to find blogs that I didn't know, and see stories that I had missed. Via Rants From The Rookery , I found this story:

A lightweight solar-powered plane has smashed the official world record for the longest-duration unmanned flight.

UK defence firm Qinetiq, which built the Zephyr unmanned aerial vehicle, said it flew for 54 hours during tests.

The researchers believe it is the first time a solar-powered craft has flown under its own power through two nights.

The previous unmanned endurance record was set in 2001 by a jet-powered US Air Force Global Hawk surveillance aircraft which flew for more than 30 hours

The Zephyr's 54-hour endurance flight will not enter the record books because representatives from the world air sports federation - the FAI - were not notified about the secretive test.

However, they were informed about a second, 33-hour flight which could still become an official record.

Zephyr's development team say that whatever the result, it believes it has built a record breaker.

Cool stuff! Thanks, Ellroon.