A prototype solar-powered airplane completed several important tests last Thursday and Friday.

Solar Impulse's HB-SIA, which was finished this past summer, taxied down a runway using power from the 11,000 solar cells covering its wings and did a series of acceleration and braking tests. The next test will be revving up the plane to its 35km/hour take-off speed.

Founder of Solar Impulse, Bertrand Piccard, a former astronaut and the first man to circle the world nonstop in a balloon, hopes to perform the same feet in a solar-powered plane derived from on the HB-SIA design. Solar Impulse aims to test the prototype in flight next year and to achieve a 36-hour flight without fuel shortly after that. Results from these tests will be used to build a solar-powered plane to will attempt a transcontinental flight sometime after 2012.

A number of solar-powered aircraft exist already, such NASA's Helios, the Solar Riser glider or the Sunseeker which flew across the US in 1990 using a mix of solar power and gliding.

The Solar Impulse prototype is made of lightweight materials, weighing only 3,500 pounds and it has a wingspan of 210 feet. It is intended to fly at only 28 miles per hour to keep energy consumption low. It will store solar energy for night flight.

The video below shows computer simulations of Solar Impulse's plane, and the real thing on the runway.

The National Electric Drag Racing Association (NEDRA) is out to change the perception of electric vehicles (EVs).

"EVs are more than glorified golf carts," says Chip Gribben, the NEDRA's PR Director. "Our whole mantra has been to dispel the myth that EVs are slow and we have been pretty successful."

Founded in 1997, NEDRA organizes drag racing competitions to show off the speed that vehicles powered by electricity can reach. As interest in electric vehicles has grown in recent years, so has the popularity of NEDRA's drag racing competitions.

This isn't only reflected by growing crowds. Gribben cites major sponsorship deals and notes that several NEDRA drivers have begun getting sponsorship from battery companies. NEDRA was also recently invited to the NHRA Full Throttle Drag Racing Series in July. "The fact that we have been invited means that the racing community is beginning to take a serious look at electric drag racing and NEDRA," he says.

Check out some videos of electric vehicles burning rubber at various NEDRA competitions below.

In last September's competition, the "KillaCycle" set a new NEDRA record by going a quarter of a mile in 7.864 seconds (reaching 169 miles per hour).

At the same competition, another electric bike, the ElectroCat, set a new NEDRA record for a 48-volt street-legal motorcycle by an eighth of a mile in 13.24 seconds (reaching 52.97 miles per hour).

The video above shows a Tesla roadster racing an in OBS junior dragster in a competition held earlier this year.

In this race, a Tesla roadster goes up against an electrified 1972 Datsun 1200, called White Zombie.

In this clip another electric drag bike, AGNS, makes a run.

Credit: Boeing

It's not easy being a green airliner. The 787 Dreamliner--Boeing's midsize, fuel-efficient passenger jet--is being delayed again.

The maiden flight of the 787--already two years overdue--was to take place on June 30, but today Boeing announced an indefinite delay to add more structural reinforcements.

"Consideration was given to a temporary solution that would allow us to fly as scheduled, but we ultimately concluded that the right thing was to develop, design, test and incorporate a permanent modification to the localized area requiring reinforcement," Scott Carson, president and CEO of Boeing's commercial-airplanes division, explained in a statement. "Structural modifications like these are not uncommon in the development of new airplanes, and this is not an issue related to our choice of materials or the assembly and installation work of our team."

Carson's mention of materials is important. The 787 is the first commercial aircraft in which major structural parts are made of composites rather than aluminum alloys. The difference slashes weight and helps boost the fuel efficiency of the plane by 20 percent. Back in 2003, we reported on this pioneering effort in commercial aviation.

Composite materials are notoriously difficult to model. Their fiber layers are oriented in different directions, and each layer is made of many individual fibers that vary somewhat in thickness. Such complex materials are far harder to precisely re-create in computer models, compared to monolithic chunks of aluminum. And Boeing has encountered trouble with 787 composites before. As we reported last spring, the company said that parts of the 787's composite-made wing box--the major structural piece inside each wing, measuring more than 15 meters by 5 meters and weighing 55,000 pounds--had buckled in stress tests. To fix that problem, Boeing added new pieces and brackets and rerouted wiring to accommodate the retrofits.

The new schedule for the first flight--and the first delivery of some of the 865 787s that have been ordered by airlines--will not be available for several weeks, the company said.