MONROVIA, CA--The tiny, rocky outcrop was an unlikely easy
chair, but it did provide the lonely and scared climber a place to rest and wait
for rescue. He had been stranded there on the down-sloping ledge for hours,
inches away from a 70-ft vertical drop to eternity. Night was falling, the
temperature was dropping, and there was no sign that anyone had heard his cries
for help. Legs and arms aching, heart pounding with fright and fatigue, his mind
raced with the usual thoughts of someone in danger: How did he get into this
spot? How would he get out? If he didn't, would his family be okay without him?
What would be the best design strategy for low-speed flight? Design strategy?
Low-speed flight?
Yes, in one of the most perilous situations of his life--stranded overnight
while climbing in California's San Gabriel Mountains on Thanksgiving Day
1993--Paul MacCready was still thinking of pioneering design ideas. By the time
of his early-morning helicopter rescue, he had actually come up with a draft
concept. Not a good design, mind you, but, typically, it would prove a valuable
catalyst that would unleash a process that would eventually produce a concept
worth pursuing.
No one who knew him was surprised--either at his perch on the ledge, or at
the owlish-looking engineer's calm persistence, despite the odds, in roughing
out a new design idea.
In a career that dates back to his boyhood in Connecticut when he began
building model airplanes, Paul MacCready, B.S. and M.A. in physics and Ph.D. in
aeronautics, has followed many technology paths that others said would lead
nowhere. He persisted. They eventually applauded.
Today, he is known as the father of human-powered flight for his design of
the Gossamer Condor. Tomorrow, he could be known as the godfather of
solar-powered stratospheric flight for his influence on the Pathfinder,
Centurion, and Helios solar planes his company is developing. They are spinoffs
of his Solar Challenger, a plane that in 1981 made the first long-distance
piloted flight powered solely by sunbeams.
Or, they might say he brought silent flight to the masses, if his ideas about
the "Owl," a two-person plane that makes almost no sound, get off the ground. He
envisions the 100-mph plane, which will take off at 20 mph, as an inexpensive
and socially desirable substitute for helicopters. Will it fly? His own history
puts the odds in his favor. Consider these accomplishments:
Winning the long-standing Kremer Prize for the first sustained, controlled
flight by a heavier-than-air craft--the famed 70-lb Gossamer Condor--powered
solely by its pilot's muscles. The 1977 feat showed how much could be done
with very little in the way of resources. The Condor is now housed in the
Smithsonian National Air and Space Museum, adjacent to Lindbergh's Spirit of
St. Louis and the Wright Brothers' 1903 Flyer.
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Human-powered flight across the English Channel. In 1979, his Gossamer
Albatross, with the same 70-lb weight and 96-ft wing span as the Condor,
crossed the Channel in turbulent winds in three hours. Cyclist Bryan Allen,
who pedaled the Gossamer Condor, also provided the human power for the
Albatross.
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The Pointer, a 9-lb, 9-ft, video-equipped surveillance drone. This silent,
battery-powered airplane requires no prepared launch/landing area because it
is hand-launched and rugged enough to land in a full-stall vertical descent.
And there's more. The remotely controlled, 120-ft-span, solar-powered
Pathfinder Plus reached 80,000 ft, far higher than any previous propeller
aircraft. It's one of a series of vehicles developed with NASA support by
engineers at AeroVironment, the company MacCready founded in 1971. Another, the
206-ft Centurion, started test flights in late 1998. Though he had little
day-to-day involvement with these latter two designs, his vision and
persistence, all agree, played a big part in their success. Now, the team is
developing Helios, a regenerative-fuel-cell-powered aircraft that would stay up
for months at a time. The vehicles could perform stratospheric communications
relay functions, and monitoring for assessing and describing the mechanics of
global climate change.
Back on terra firma, he has made his mark as well. He guided the team that
developed the GM Sunraycer, a solar-powered car that won a 1,867-mile race
across Australia. MacCready's team, with GM support and help, then developed the
Impact demonstrator electric vehicle, which in 1991 stimulated California's
zero-emissions mandate. The Impact became the currently available EV1.
Each achievement, from the model airplanes of his boyhood to the latest
solar-powered craft, laid the groundwork for the next as he and AeroVironment
engineers applied what they learned.
The vision thing. "Paul MacCready does things
unconventionally," says Howard Wilson, former vice president at Hughes Aerospace
who worked with the AeroVironment team on development of the Sunraycer and
Impact. "He is a free thinker who follows his own paths, and that characteristic
attracts very bright people to work for him."
MacCready insists that it's those AeroVironment engineers who deserve the
credit for breakthroughs often associated with his name. Indeed, they do the
heavy lifting on development of products that spring from his and their own
imaginations. But the AeroVironment teams credit him for his vision, and for
planting the seeds and nurturing the growth of company-wide capabilities.
Says Tim Conver, president of AeroVironment, "He is the chief visionary
officer, almost child-like in his optimism, and he is open to ideas and
possibilities many of us aren't open to. Once he has an idea, he's tenacious."
"It's a running joke around the company that any seemingly wacky idea he has
will eventually get funding from somewhere," says Matthew Keennon,
AeroVironment's program manager for MAVs. "He breaks down problems to the
smallest nugget, then lashes something together fast and drives down the street
with it hanging out the car window to see how it works."
MacCready's penchant for hands-on research and quick-and-dirty prototypes is
legendary--and, in fact, he preaches the value of both to students and
colleagues alike. "If you want to do something, just go out and do it," he says.
"When you're pioneering something, quick-and-dirty can be elegant." The one
caveat he offers: Don't disobey the laws of Newton, Carnot, and other scientific
thinkers.
He crystallizes his own thinking about engineering problems in many ways,
including exaggerating the physics involved. Case in point: While trying to
solve stability and control problems on the Gossamer Condor, he supplemented
computer simulations on apparent mass with personal observations. Apparent mass
is the effective mass of air to which a vehicle's accelerations are coupled, and
it's connected to vehicle size and shape. For the Condor, it seemed to MacCready
to be the culprit for making the vehicle dynamically unmanageable.
Extensive computer simulations merely verified the problem's existence, but
gave him no insights on how to fix it. So, he concocted a simple 3-ft balsa
model and pushed it through the water in his swimming pool. The forces resulting
from using a fluid almost 1,000 times as dense as air exaggerated the effects,
and he could feel them in his hand, which substituted for a wind-tunnel balance.
He banked the model without yawing and yawed it without banking and quickly got
the breakthrough insight for a successful Condor configuration. He made the wing
tips smaller to decrease mass effects during yaw and roll, and modified the
control systems to accept rather than fight apparent mass.
The swimming pool isn't the only makeshift lab MacCready has used. Alec
Brooks, vice president and chief technical officer of AeroVironment, recalls a
more mobile one he employed during design of the Solar Challenger.
On his orders, the design team mounted the Challenger's wings on a van. "Paul
strapped himself on the wings and used a control stick while the van was
traveling to 50 mph to find where the aileron reversal of the flexible wing
would make flight dangerous," Brooks remembers.
Of course, MacCready is perfectly capable of using more traditional testing
venues, but even there he adds his own twist. "While working on the Sunraycer,
Paul stood in the GM wind tunnel with the wind blowing and put a stethoscope
with a pitot tube on the car to see if the point where the boundary layer
tripped from turbulent to laminar was consistent with theoretical predictions,"
Brooks says.
The model youth. That kind of first-hand observation and
investigation is a habit MacCready developed as a 13-year-old building model
airplanes. Too small to be a star athlete, too shy to be a student leader, he
found fulfillment designing and building the models and winning contests with
them. "Doing the models, I had to take total responsibility," he says.
He also eventually got involved in flying sail planes, and continued his
pioneering efforts. In 1947, he invented the MacCready Speed Ring, a concept
used by glider pilots worldwide to select the optimum flight speed between
thermals. In 1948, 1949, and 1953 he won the U.S. National Soaring Championship,
and in 1956 was the first American to win the International Championship. For
those accomplishments, the French, with their keen sense for the nuance of
language, dubbed him "Le Machine."
Four years earlier, he earned his Ph.D. in aeronautics from the California
Institute of Technology. He met and had many discussions with Irving Langmuir, a
Nobel Prize-winning chemist who was one of the pioneers in weather modification,
and was inspired by the latter's disregard for barriers and conventional wisdom.
"He would plunge into a new subject, ask a lot of questions, make mistakes,
distill the essence, and create advances," MacCready recalls.
It was an approach that felt natural to MacCready, and he wanted to take it
to a large company after college. "But none were doing the kind of pioneering
work I wanted to be involved in," he says. "The exciting thing about pioneering
is that there is no program or record to help you get the right answers. You
don't even know the right questions."
The best way to pioneer in America is to start your own company, and
MacCready did. His Meteorology Research Inc. became a leading firm in weather
modification and atmospheric science research. He was the first to use small
instrumented aircraft to study storm interiors, and performed many of the
piloting duties. In 1971, he sold the company and, after a short stint
consulting, started AeroVironment Inc., which today provides services and
products in the fields of environment, alternative energy, and energy-efficient
vehicles.
The project that solidified MacCready's reputation and that of his
company--and which laid the groundwork for so much of what he and AeroVironment
engineers have accomplished--was the Gossamer Condor. But, it was no great
strategic plan that got him into the project. He had co-signed a loan for a
relative who defaulted. While pondering how he would make the loan payments, he
remembered the offer that British industrialist Henry Kremer had made several
years before. Kremer promised $95,000 to the first person to use human power to
fly a plane along a prescribed course. The plane would have to trace a figure
eight around two markers four-fifths of a kilometer apart. Seeing the prize as
his way out of debt, he went to work.
The effort took him into uncharted territory, and there were plenty of
problems to solve. Power, steering, and extremely light-weight materials were
just a few of the challenges. Other groups had been successful in getting a
human-powered craft off the ground, but no one had been able to build such a
plane that would turn. When they turned at those low altitudes (about 15 feet),
they always crashed.
A different path. Most Kremer contestants stressed drag
reduction through aerodynamic efficiency and streamlined airframes. MacCready
took a different path. The combination of large size and low weight would more
than compensate for an inelegant and simple--thus, quick and
cheap--construction, he reasoned. So, he designed 96-ft wings made of aluminum
tubing, corrugated cardboard, and balsa wood, and made the wings rigid with
exterior bracing of piano wire. The covering was Mylar, from DuPont, which
became a sponsor of some of his later projects.
The design technology he used would be of no help to engineers using CAD and
finite element analysis for airliners, he admits. But, the focus on efficiency
trickled down to other projects. "We got a lot of people at AeroVironment to
think about doing more with less, both as a design approach and as a category of
devices that would operate with the low power of muscles, batteries, and
photovoltaic cells" he says. One consequence was long-term funding, now by NASA,
of solar planes such as the Solar Challenger, Pathfinder, Centurion, and Helios.
No fear of failing. To be a pioneer requires a certain
amount of fearlessness. His associates say MacCready fears neither criticism nor
failure. "He gets plenty of resistance," says AeroVironment's MAV Program
Manager Keennon, "because his ideas at first seem so way out." But, adds Ray
Morgan, director of AeroVironment's design development center, "he is very
reluctant to give up on an idea. He is famous for saying, 'I bet one could
just…'"
His fearlessness and zest for pioneering extend to his personal life as well.
Last summer he and his wife Judy vacationed in Africa visiting nature parks that
most tourists don't see, and where you have to be accompanied by armed guards as
you walk to the next tent. A couple of years before that, he rafted on the Upper
Yangtze River in Tibet, where few westerners had ever been. "He had more fun
than anyone on the trip," recalls Judy. "He enjoyed the mix of nature and
mingling with Tibetans who have little contact with the outside world."
'Ambivalent Ludite.' In fact, he frets that humans in
general are having little contact with nature, or with their own selves.
Ironically for a person who has made so many engineering breakthroughs in his
life, he considers technology a mixed blessing.
Calling himself an ambivalent Ludite, this philosopher-engineer
says,"Technology can disconnect us from life. E-mail lets us work faster, but
somehow we have less time to sit, digest, and enjoy. Cars give us wonderful
mobility while they erode our motivation to walk, exercise, and meet our
neighbors."
MacCready says that the human mind is at present "the most powerful force on
earth," but acknowledges that the number of things humans can do that computers
can't do is dwindling. "Technology in perspective and under control is great,
but as a master it's worrisome," he laments. So, he spends some of his free time
encouraging students to develop thinking skills and what he calls their unique
human ability to deal with big themes. "They don't have the limiting factor of
expertise," he says. "I encourage them to unleash their minds."
That's something he says the country's public education system doesn't
encourage. "Students are rewarded for the right answer, not for learning from
mistakes, nor for seeing multiple sides to an issue and comprehending the big
picture, and definitely not for asking a new question," he asserts. "We need
people able to perceive reality and contemplate our future options as
civilization changes faster and faster. We need a nation of wolves and
revolutionaries, but the schools are giving us sheep."
Asking questions is a lifestyle for Paul MacCready. And in finding his own
answers, he has changed the fields he works in. He recalls that while perched
all night on that rocky ledge in the San Gabriels he kept thinking about what
Dorothy asked the Scarecrow in The Wizard of Oz: "If you had a brain,
what would you do with it?" MacCready's career shows the possibilities.
Mechanical Insects
AeroVironment is a leader in the emerging field of micro air vehicles (MAVs).
These tiny craft, about the size of insects on steroids, have several potential
military uses, hence the interest of the U.S. Defense Advanced Research Projects
Agency (DARPA) in their development. DARPA is funding several MAV projects, with
an eye to using the best designs for reconnaissance operations.
|
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Detail diagram of future Black Widow. The current version does not
have the camera and thenavigation systems, such as GPS, gyros, and
airspeed sensor. |
In general, MAVs have maximum dimensions of six inches and weigh no more than
65 grams. Flapping wings propel some. All will contain small video cameras,
motors, and actuators.
Minimum power requirements for MAV flight, assuming 50% prop efficiency and
50% motor efficiency, might be five watts from the battery. Hovering flight with
a 15-cm-dia. prop takes three or four times as much power as the minimum for
level cruising. Controls, servos, video, and telemetry consume less than a watt
for a typical short-range system. High-resolution video, with wider frequency
band requirements and ranges of several kilometers, increases the power needs.
Matthew Keennon, the company's MAV program manager, has come up with servos of
less than 0.3 gms. Such mechanical miniaturization, combined with microchips,
lets vehicles edge toward bird capabilities.
While Paul MacCready has little day-to-day involvement in AeroVironment's MAV
activities, they borrow heavily from his early work with model airplanes. During
talks on innovation, he sometimes flies a 1.4-gm shimmering ornithopter given
him by a modeler friend, Warren Williams. The flight seems like an art happening
with no practical purpose, but MacCready points out that if he hadn't been
creating equivalent models as a youngster in 1939, there would be no Gossamer
Condor, Solar Pathfinder, or EV1, though he admits that equivalents would have
eventually emerged from another source.
Says Keennon, "He pours out many ideas. Many of them are just improvements,
very few are cosmetic. He is always thinking of how to make something better."
Follow the sun
In late November 1998, AeroVironment's Centurion solar-powered aircraft took
its maiden flight. The remotely piloted aircraft is designed to fly to 100,000
ft on sun power alone. It consists mostly of an eight-ft wide wing spanning 206
ft. Four landing-gear pods support the wing. The vehicle's lift-to-drag ratio is
about 32 at sea level and 23 at 100,000 ft. It is designed to stay aloft for 24
hours or more, even without energy storage except for potential energy of height
times weight.
Next up for the company will be the Helios, an evolution of the Centurion
platform that will incorporate a regenerative fuel-cell energy storage system to
provide power for flying through the night. The Helios, say AeroVironment
engineers, will be capable of continuous flight for months at a time at
altitudes of 50,000 to 70,000 ft, and could be used for communications, imaging,
reconnaissance, and positioning.
Both craft are offsprings of earlier work Paul MacCready and Ray Morgan did
on solar-powered flight, starting with the Gossamer Penguin in 1980 and the
Solar Challenger in 1981. The Challenger, in particular, posed engineering
problems that would present themselves in future solar craft. It had to fly high
above the ground in turbulence, which meant it had to be very strong while still
light. With the support of DuPont, MacCready and his team developed new
structural techniques. Airplanes use the strength of the wing skin to handle
torsion. For the solar planes with only a wing span of thin plastic, MacCready
decided the spar would have to do the work.
The Pathfinder Plus set the world propeller altitude record in 1998, soaring
to 80,200 ft on solar power.
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