AeroVironment's unmanned solar-powered aircraft technology is one step closer to becoming a low-cost, flexible, alternative satellite platform for telecommunications and other applications.

Engineers at NASA's Dryden Flight Research Center say that the

initial low-altitude flight tests of the remotely piloted Centurion

airplane were an unqualified success, following the conclusion of the

series with a third and final flight Dec. 3.

Project officials noted that all of the objectives of the series

were met ahead of schedule. Four to seven missions had originally been

planned, but the test series was completed in only three flights.

Although Centurion did its initial test flights with batteries,

the upper surface of the 206-foot-long Centurion will eventually be

covered with solar cells to support program officials' plans to

achieve high-altitude flight tests to 90,000 to 100,000 feet.

An earlier version of the plane, the Pathfinder Plus, achieved a

world record height for a propeller-driven airplane of 80,000 feet in

tests at the Pacific Missile Range Facility (PMRF) in Hawaii in August

of this year. That plane flew entirely on solar power.

Last Thursday's flight represented the 43rd consecutive

successful flight of this type of solar aircraft. NASA has sponsored

development of the Pathfinder under the Environmental Research

Aircraft and Sensor Technology (ERAST) program.

The Centurion is the latest evolution of AeroVironment's solar

aircraft platform, refined and proven over more than a decade.

Centurion is a production prototype designed to validate the

technology for the next and ultimate step, Helios, a long-endurance

derivative of the Centurion design.

Helios will incorporate energy storage for nighttime flight and

be capable of continuous flight for six months at a time at altitudes

of over 60,000 feet on telecommunications or science missions. The

ERAST program is working to develop the technology base for a future

fleet of such remotely piloted aircraft.

For its final flight the Centurion carried a simulated payload of

more than 600 pounds — approximately half the lightweight aircraft's

empty weight. John Del Frate, the NASA program manager, noted the

airframe "really has the muscle to do big jobs."

Bill Parks of AeroVironment, Centurion's chief engineer and

flight test director, noted the high gross-weight payload was a major

objective of the flight test program: "We verified the performance of

the aircraft while flying in a high gross-weight configuration.

"We came here with a new variant of our proven platform and it

performed exactly as expected; there were no aircraft systems failures

that had to be corrected. It doesn't get any better than that," Parks

added.

Ray Morgan, vice president of AeroVironment's Design and

Development Center, noted that the Centurion altitude and payload

targets are significantly higher than those of eventual Helios

telecommunications applications (100,000 feet versus 50,000-70,000

feet, and 600 lbs versus about 200 lbs payload). "We've purposely

overdesigned the plane versus its likely commercial missions."

The successful record flight is one more milestone on the way to

commercial solar-powered aircraft becoming low-cost complements to

satellites.

According to Tim Conver, president of AeroVironment: "Until now,

there has been only one sort of high-altitude, long-duration platform

available — satellites. High-altitude solar planes will be

cost-effective as a substitute or complement for many applications

currently performed by satellites.

"They can relay communications signals. They can take photos.

They can track hurricanes. They can do exactly what a satellite does,

but more flexibly and with less investment. We are looking at

telecommunications applications as a major possible avenue of growth

for AeroVironment," Conver concluded.

For some communications applications, Helios will have critical

advantages over satellites: distance, location and recovery. At under

15 miles altitude, solar airplanes are much closer to the ground than

any satellite, allowing use of much cheaper transmitters and reuse of

scarce frequency spectrum. Because solar airplanes can land and take

off as needed, their payloads can incorporate the latest technology

and avoid obsolescence.

At well under $10 million each in production, solar airplanes can

also be significantly less expensive than satellites, which can cost

up to $100 million or more to build and launch. Given these advantages

and the success of the plane's development program, the commercial

future for solar airplanes looks very promising.

Morgan believes "It's inevitable that, in the future,

solar-powered aircraft will be operating routinely as stratospheric

satellites."

David Nufer, chief marketing executive of AeroVironment, noted

that there has been significant interest among aerospace and

telecommunications firms in the Helios solar platform and that "we are

pursuing these potential opportunities aggressively."

AeroVironment has long been known as the leader in solar flight.

Other pioneering air vehicles produced by AeroVironment have

included the human-powered "Gossamer Albatross," and the solar-powered

"Gossamer Penguin" and "Solar Challenger." In 1981, the Solar

Challenger flew 163 miles from Paris to London, at altitudes up to

11,000 feet, powered only by the sun.

The Solar Challenger is now owned by the Smithsonian Institute's

National Air and Space Museum. Ground-breaking land vehicles have

included the "Sunraycer" solar-powered car and the "Impact" electric

car, forerunner of the General Motors EV1.