Boeing Solar Eagle

Its a bird…. its a plane…. its the High Altitude Long Endurance and Solar Eagle (previously called the Vulture).  The unmanned aerial vehicle (UAV), designed and built by Boeing, is a Defense Advanced Research Projects Agency (DARPA) venture that will rely primarily on solar power to accomplish its tasks.  With a wingspan of 400-feet, the Boeing Solar Eagle will be able to stay at altitudes of 60,000 feet while carrying 1,000 pounds of equipment using solar energy and ultra-efficient electric motors and propellers.

According to DARPA’s website:

Department of Defense demands for surveillance, intelligence and reconnaissance data from both airborne and space-based (satellite) assets are steadily increasing. Meeting these demands has become progressively more challenging with current technologies. The Defense Advanced Research Projects Agency (DARPA) is working on a solution to combine the advantages of both asset types. Vulture will develop and demonstrate the technology to enable a single high-altitude unmanned airplane to operate continuously on-station, unreplenished, for a period of five years.

DARPA awarded the contract for the solar powered spy plane to Boeing, including the $89 million required to build the aircraft.  The Solar Eagle will soar over hostile regions, maintaining targets, much like a satellite, but with the ability to change location as needed.  Solar energy absorbed during day-light hours will be stored in fuel cells for continued use of the renewable resource over night.  Because of the glider-like design of the Solar Eagle, the plane will be able to stay at high altitudes for long periods of time without the need to refuel.

The solar airplane is due to be launched in 2013, during the winter solstice.  Phantom Works, a research and development arm of Boeing, is developing the Solar Eagle.

Aurora Flight Sciences Solar Powered Aircraft

We’ve blogged about solar powered airplanes in recent months, but the interest has seemed to be with respect to their novelty, rather than a real potential way to address the massive amounts of fuel consumed by aircraft (and corresponding CO2 emissions).

Recognizing the need for a variety of aircraft to serve multiple purposes, Virginia-based Aurora Flight Sciences has focused on unmanned aerial vehicles (UAVs) that can be flown without pilots or passengers to carry cameras, computers and other equipment.  For military, homeland security and space exploration, solar UAVs would be perfect.  Saving on fuel and extending flight time are two of the primary benefits of using the renewable energy resource.

Last week, Virginia-based Aurora Flight Sciences announced that it had finished the fabrication and initial tests of a wing design that could revolutionize solar-powered aircraft.  The company, which specializes in the design and construction of unmanned aircraft, created a test plane wing with a span of 22 feet that is constructed of composite materials and lightweight plastics.  Advanced solar cells cover the top of the wing, which convert sunlight into electricity for use to power the aircraft and its payloads.

Solar UAV from Aurora Flight Sciences

Aurora CEO John Langford enthused:

“Our very first externally funded study, in 1989, was for a solar-powered version of the Daedalus human-powered aircraft. Today’s designs are for much larger aircraft — literally hundreds of feet in wingspan. The idea of this test panel was to develop and validate designs and manufacturing techniques. Doing this is essential for the accurate planning of any future solar aircraft development program.”

The company has been working on a viable solar plane – and one with long-range capabilities – for some time:

Aurora was selected as a contractor by the U.S. Defense Advanced Research Projects Agency (also known as “DARPA”) in 2008 to work on the “Vulture” ultra-long endurance aircraft program.  The large solar test panel announced last week was privately funded as an adjunct to the Vulture project.  In addition, Aurora funded the development/flight test of SunLight Eagle, another solar UAV (unmaned aerial vehicle) with a huge 114-foot wingspan last year.

Solar Impulse aircraft

Of all the major greenhouse gas emitting sources in the world, commercial air travel is one of the biggest offenders.  Now, there is hope for cleaner, greener flights.

The Solar Impulse is a giant, 4-motored electric airplane that is covered with more than 12,000 PV solar cells on its wings, fuselage and horizontal stabilizer.

According to the Solar Impulse web site:

At midday, each m2 of land surface receives the equivalent of 1000 Watts, or 1.3 horsepower of light power. Over 24 hours, this averages out at just 250W/m2. With 200m2 of photovoltaic cells and a 12 % total efficiency of the propulsion chain, the plane’s motors achieve no more than 8 HP or 6kW – roughly the amount of power the Wright brothers had a available to them in 1903 when they made their first powered flight.

Wikipedia states:

The plane is as wide as an Airbus A340. Under the wing are four gondolas, each with a set of lithium polymer batteries, a 10HP motor and a twin-bladed propeller. To keep the structure ultra-light, a customized carbon fibre honeycomb sandwich structure is used.

Wondering how the Solar Impulse can keep flying overnight?  One word: batteries.  And now 5 words: How much do they weigh?

At 400 kilograms, the batteries comprise 1/4 the total weight of the airplane, but they’ll be equally dispersed across the entire mass.  Lithium polymer batteries will be insulated, as well, to prevent freezing at the massively cold -40 degrees Celsius temps at more than 27,000 feet elevation that the solar plane will fly.

The average cruise speed will be 70 km/hr, so it will take approximately a week to complete the trip, which is to be made in four long legs starting on the Persian Gulf, across southeast Asia, then across the Pacific to Hawaii. From Hawaii, a two-man crew will fly two nights straight, landing in Miami, Florida. From Florida they will cross the Atlantic to North Africa and then back to the Gulf. The route of the flight is depicted in a Flash animation.

Are we on the cutting edge of emissions-free airplane travel?  Yes, say the project’s promoters.  In fact, a second airplane is planned for 2011, which will include a pressurized cabin to allow for trans continental and trans-oceanic flights.  And plans for an around-the-world flight are in the works for 2012.

Who would have thought… a solar airplane?  Actually, come to think of it, why not?