Electric Icarus: NASA Designs a One-Man Stealth Plane
Could the Puffin, an electric-powered flying suit, change the way we use the sky in war and peace?
January 19, 2010
FLYING FANCY: Another design for
a single-passenger/pilot aircraft makes the future of transportation
look extremely fun and a little bit green
Image: NASA Langley/Analytical Mechanics Associates
A super-quiet, hover-capable aircraft design, NASA's experimental
one-man Puffin could show just how much electric propulsion can
transform our ideas of flight. It looks like nothing less than a flying
suit or a jet pack with a cockpit.
On the ground, the Puffin is designed to stand on its tail, which splits into four legs to help serve as landing gear. As a pilot prepares to take off, flaps on the wings would tilt to deflect air from
the 2.3-meter-wide propeller rotors upward, keeping the plane on the
ground until it was ready to fly and preventing errant gusts from
tipping it over. The Puffin would rise, hover and then lean over to fly
horizontally, with the pilot lying prone as if in a glider. When
landing, the extending spring legs would support the 3.7-meter-long,
4.1-meter-wingspan craft, which is designed with carbon-fiber composites
to weigh in at 135 kilograms, not including 45 kilograms of rechargeable lithium phosphate batteries.
In principle, the Puffin can cruise at 240 kilometers per hour and dash
at more than 480 kph. It has no flight ceiling—it is not air-breathing
like gas engines are, and thus is not limited by thin air—so it could go
up to about 9,150 meters before its energy runs low enough to drive it
to descend. With current state-of-the-art batteries, it has a range of
just 80 kilometers if cruising, "but many researchers are proposing a
tripling of current battery energy densities in the next five to seven
years, so we could see a range of 240 to 320 kilometers by 2017," says
researcher Mark Moore, an aerospace engineer at NASA's Langely Research in Hampton, Va. He and his colleagues will officially unveil the Puffin design on January 20 at an American Helicopter Society meeting in San Francisco.
Moore and his colleagues at NASA, the Massachusetts Institute of
Technology, the Georgia Institute of Technology, the National Institute
of Aerospace, and M-DOT Aerospace named their craft the Puffin because
"if you've ever seen a puffin on the ground, it looks very awkward, with
wings too small to fly, and that's exactly what our vehicle looks
like," he explains. "But it's also apparently called the most
environmentally friendly bird, because it hides its poop, and we're
environmentally friendly because we have essentially no emissions. Also,
puffins tend to live in solitude, only ever coming together on land to
mate, and ours is a one-person vehicle."
This design relies on electrical engines.
These remain efficient regardless of their size, whereas internal
combustion engines become less efficient the smaller they are. As such,
electric aircraft can use small motors while generating impressive
propulsion—the Puffin can lift a person with just 60 horsepower.
At up to 95 percent efficiency, electric motors are far more efficient
than internal combustion engines, which only rate some 18 to 23 percent.
This means electric aircraft are much quieter than regular planes—at
some 150 meters, it is as loud as 50 decibels, or roughly the volume of a
conversation, making it roughly 10 times quieter than current low-noise
This super-quiet quality makes the Puffin potentially ideal for covert
military insertions of special operations units and other troops—indeed,
it was originally aimed to launch from submarines; unmanned versions
could also help transport supplies. Quieter aircraft also mean that
airports for civil applications such as personal travel and fast courier
services could be located much closer to population centers and perhaps
even residences without bothering others, significantly cutting down
commute times. Inventors all over the world are still striving to
develop personal air vehicles, the equivalent of a plane in every
garage—for instance, Samson Motorworks is trying to develop a land/air capable motorcycle.
In addition, since electric motors are so efficient, they also generate
far less heat. This not only gives them a lower thermal signature for
but means they don't need anywhere near the same amount of cooling air
flowing over them that internal combustion engines do, thereby reducing
aerodynamic drag that can slow them down.
Because electric motors have fewer moving parts, they are perhaps 10 or
even 20 times more reliable than piston engines. In addition, the
Puffin's design allows pieces of either of its two electric motors to
fail without any reduction in power to the prop rotors. The plane could
also take a hard, forceful landing if necessary, as the landing gear
supports the brunt of the load instead of the pilot, unlike some other
one-man flying craft.
"The Puffin is an exciting idea.... It converges and demonstrates many
technologies at once," said Brien Seeley, president of the Comparative Aircraft Flight Efficiency (CAFE) Foundation,
a Santa Rosa, Calif.–based independent flight test agency that hosts
the annual Electric Aircraft Symposium. "In my opinion, a
mass-marketable version will need conventional seating, cup holders and a
short runway for glide-in, view-ahead landings—but opening up people's
imagination is the first essential step."
By March, the researchers plan on finishing a one third–size,
hover-capable Puffin demonstrator, and in the three months following
that they will begin investigating how well it transitions from cruise
to hover flight. They are already looking past the Puffin, however. The
next-generation of this design might incorporate more than just two
pairs of prop rotors, so that if one was struck by, say, a bird or
gunfire, the aircraft could survive on redundant systems. "We could make
it so there's no single point of failure—that's the cool next step,"