Beam Up Some More Power, Scotty!
ANN Reader James noted that we hadn't
mentioned the lowest-powered flight of the month. It's quite
significant, and we've led up to it for a while now, even
giving you notice of its
success -- but NASA has released details, and
some photos of just what it takes, to fly an airplane on laser
power. While only the light source is really different (electric
planes have been in the air for years), laser light is so
concentrated that relatively little power is lost; additionally, a
laser-powered plane wouldn't have to start gliding homeward at
dusk. Here's what NASA now has said about it:
Ever since the dawn of powered flight, it has been necessary for
all aircraft to carry onboard fuel -- whether in the form of
batteries, fuel, solar cells, or even a human "engine" -- in order
to stay aloft.
But a team of researchers from NASA's Marshall Space Flight
Center in Huntsville (AL), NASA's Dryden Flight Research Center at
Edwards (CA), and the University of Alabama in Huntsville is trying
to change that.
They have now chalked up a major accomplishment... and a
"first." The team has developed and demonstrated a small-scale
aircraft that flies solely by means of propulsive power delivered
by an invisible, ground-based laser. The laser tracks the aircraft
in flight, directing its energy beam at specially-designed
photovoltaic cells carried onboard to power the plane's
propeller.
"The craft could keep flying as long as the energy source, in
this case the laser beam, is uninterrupted," said Robert Burdine,
Marshall's laser project manager for the test. "This is the first
time that we know of that a plane has been powered only by the
energy of laser light. It really is a groundbreaking development
for aviation."
"We feel this really was a tremendous success for the project,"
added David Bushman, project manager for beamed power at Dryden.
"We are always trying to develop new technologies that will enable
new capabilities in flight, and we think this is a step in the
right direction."
The plane, with its
five-foot wingspan, weighs only 11 ounces and is constructed from
balsa wood, carbon fiber tubing and is covered with Mylar. Designed
and built at Dryden, the aircraft is a one-of-a-kind,
radio-controlled model airplane. A special panel of photovoltaic
cells, selected and tested by team participants at the University
of Alabama in Huntsville, is designed to efficiently convert the
energy from the laser wavelength into electricity to power a small
electric motor that spins the propeller.
The lightweight, low-speed plane was flown indoors at Marshall
to prevent wind and weather from affecting the test flights. After
the craft was released from a launching platform inside the
building, the laser beam was aimed at the airplane panels, causing
the propeller to spin and propel the craft around the building, lap
after lap. When the laser beam was turned off, the airplane glided
to a landing.
The team made a similar series of demonstration flights in 2002
at Dryden, using a theatrical searchlight as a power source. The
recent flights at Marshall are the first known demonstration of an
aircraft flying totally powered by a ground-based laser. The
demonstration is a key step toward the capability to beam power to
a plane aloft. Without the need for onboard fuel or batteries, such
a plane could carry scientific or communication equipment, for
instance, and stay in flight indefinitely. The concept offers
potential commercial value to the remote sensing and
telecommunications industries, according to Bushman.
"A telecommunications company could put transponders on an
airplane and fly it over a city," Bushman said. "The aircraft could
be used for everything from relaying cell phone calls to cable
television or Internet connections."
Laser power beaming is a promising technology for future
development of aircraft design and operations. The concept supports
NASA’s mission-critical goals for the development of
revolutionary aerospace technologies.
[Thanks to Tom Tschida, Dryden Flight Research Center, for the
photos --ed.]