Visit Your Local PBS Station PBS Home PBS Home Programs A-Z TV Schedules Watch Video Donate Shop PBS Search PBS

TV Schedule
Alan Alda
For Educators
Previous Shows
Future Shows




 

Photo Paul MacCready

Dr. Paul MacCready is founder and Chairman of AeroVironment, Inc., which specializes in innovating efficient, alternatively-fueled vehicles for land, sea, and air. MacCready received his B.S. in physics from Yale in 1947, his M.S. in physics from Caltech in 1948, and his Ph.D. in aeronautics from Caltech in 1952.

In 1977, his Gossamer Condor won the $95,000 award offered by British industrialist Henry Kremer for the first sustained, controlled human-powered flight. The plane now hangs in the Smithsonian Institution's National Air and Space Museum in Washington, D.C., beside the Wright Brothers' 1903 Flyer and Lindbergh's Spirit of St. Louis.

Since then, MacCready has led teams that have created many additional pioneering vehicles. Working in conjunction with General Motors, MacCready and his group developed the GM-Impact, a battery-powered car with remarkable performance that became the catalyst for recent developments in alternatively-fueled vehicles. In 1998, the solar-powered Pathfinder II, a huge, remotely-piloted descendant of the Solar Challenger, reached the stratospheric altitude of 80,200 feet- the highest a propeller plan has ever flown.

A member of many professional organizations, MacCready is president of the International Human Powered Vehicle Association. He has been awarded numerous honorary degrees and international honors, including the 1982 Lindbergh Award for his "significant contributions toward creating a better balance between technology and the environment."

     

For links to the scientist's homepage and other related information see our resources page.

MacCready responds :

5.09.01 Tim W. Jones, Sr asked:
Dear Dr. MacCready;
Could a slow flying jet plane approaching from the left and underneath of a large propeller driven craft and in close proximity, quickly give full throttle and suck the supporting compressed air from underneath the larger plane's left wing through the jet's intake, causing the larger plane to slide left and down into the jet? If this could happen, it may have happened and would explain a Chinese pilot's declaration that our reconnaissance plane made a sudden maneuver down and left causing the collision. I am thinking that the front end of an operating jet engine is similar to a vacuum cleaner. How off base am I?
Thanks in advance for your time.
Tim W. Jones, Sr.

McCready's response:
Considering the large size, weight, and therefore lift of the U.S. reconnaissance plane, an abrupt power change by a small fighter beneath its wing would probably not have a significant effect on the big plane╣s motion. However, the vortex wake that assembles in the vicinity of the large plane╣s wing tip, and trails backward, is strong, and has often flipped over small planes that make the mistake of getting involved in it. Big following planes can be upset slightly by the vortex wake system, but are only inconvenienced, not flipped, because their wings span across the small scale flows and tend to average out the effects. The time and space persistence of these trailing wakes are the main reasons for the large spacing between landing airplanes at airports, and the resulting traffic delays and low capacity of airports.

Big planes don't move abruptly. Logic suggests that a "hot dog" fighter pilot kept zooming close in order to be annoying or threatening, misjudged a dangerous move, and caused the collision. The testimony of the other fighter pilot about the big plane initiating the accident is likely filtered by the politics of the country he represented. No pilot of a large plane with many people on board would initiate a life-threatening maneuver. Political posturing required those behind the perpetrators of the collision to an illogical "your face hit my fist" picture.

I do not have enough facts about the incident to have an absolutely definitive conclusion, but feel the charges are less than 1 out of 1000 that the cause was other than reckless maneuvering on the part of the fighter pilot.

5.09.01 Colin P. Varga asked:
I first saw your story back in 1977 regarding the Condor. It was very impressive. Do you think small passenger planes could be powered by an electric engine? Would a fuel cell be a good power source for this type of vehicle? Will solar panels be powerful enough? Thanks, Colin

McCready's response:
Planes carrying people can be battery powered. Our piloted Solar Challenger flew by battery power in 1980 during its development program. In 1981 it carried its pilot 163 miles from Paris to England at 11,000 feet, using only photovoltaic cells ("flying on sunbeams"). Some auxiliary powered sailplanes are powered by batteries, and small 2 to 4 person planes could certainly be made that could fly 100 miles on present advanced batteries, and probably 3 times further on the batteries likely to be available 5-10 years from now. Energy from burning fuel (reciprocity or rotary engine, or fuel cells) can provide much more energy per pound than can batteries, and also have high power for their weight and at relatively low cost.

For normal aircraft, where economy and long range (and occasional high power for safe takeoffs) are needed, combustion of fuel is the logical approach. If you don't want to use fossil fuels and release CO2, you can make ethanol from plants and use it to power planes in a total system that releases no CO2.

Electricity can be generated by wind or solar cells or hydroelectric systems or nuclear plants, and can be used to generate hydrogen for fuel cells or for combustion in reciprocating or rotary engines. Onboard storage is the problem.

Powering aircraft is perhaps the highest level use for liquid fossil fuel. Surface vehicles, without the priority on low weight, can more easily draw on other options. Ditto for heating.

5.09.01 John asked:
What fields do you graze in to find your best creativity? I mean, what authors, artists, musicians, scientist and other inventors inspire you?

McCready's response:
Conferences, books, magazines, newspapers, occasionally TV, interaction with associates and strangers, all provide information, insights, and stimuli. It is helpful if you have a proactive attitude and a feeling of being empowered. Even if the attitude and feeling are not justified, they put you in a proactive position of figuring out how to make things happen, rather than just studying or observing or ignoring. Most helpful were some mentors in the early 50s who expected me to do things beyond my resources or ability. I didn't want to let them down and so charged ahead and, to my surprise, found I could do more than I had thought. I find myself drawn to generalists rather than specialists, because generalists tend to find connections between fields, or discover a fertile mulch in the interactions between fields. (Youngsters are especially good at being generalists, before the stultifying effect of standardized testing erodes the enthusiasm to venture.)

One doesn't try to be creative. One just tries to solve challenges. If you can't do it this way, try another way, and another or reexamine the situation and find that some other nearby challenge is solvable.

5.09.01 Jack asked:
My name is Jack, I am an 11 year-old and I found your television show extremely interesting. I was wondering how you get proper funding for all of the materials you use for your magnificent airplanes?
Another Awestruck fan,
Jack

McCready's response:
You can focus your personal resources on helping feed your key interests rather than diluting the resources for other tasks. If you really want to do something and communicate it to lots of people, you often find someone (or some organization) that wants to help. (I have found that everything that deserves being done eventually gets support, although it may be many years before the support materializes.) You can't do much alone. Asking for help, and ignoring rejection, are important.

5.09.01 Michael Gibbs asked:
Greetings to another Caltech grad. I also have a degree in Physics from there. My question is: What is the latest progress on the attempt to make a human powered helicopter? I think a scaled down version might be a good candidate for a vehicle that can hover and carry a small camera. What do you think?

McCready's response:
The reality of a human-powered helicopter is that, with the simple formula for static thrust of a rotor, you quickly find you need a disk diameter of 150 feet or so for serious human-powered helicopter flight. It can be done, but the task is huge, and the dollar prize not worth the time expenditure. There are many more exciting, never-been-done-before challenges that can be accomplished with much less work.

5.09.01 Jack Conway asked:
Was very impressed with your story on "Flying Free" with Alan Alda. Made me feel like a kid again. Saw the segment on using insect wings to discover their "heavy lifting" abilities. What about the Bumble Bee, the one insect that is too heavy to fly -but does anyway? Just thought I'd throw in my two cents just in case someone had overlooked it.
Thanks for your time and keep inventing!!

McCready's response:
The old bumblebee myth is a combination of science and media. Bumblebees fly. They have some great tricks up their sleeves that humans didn't understand fully because the tricks don't help at the scale of planes that carry humans. As interest in microfliers grows, so does attention to the varied flight solutions of insects. There is superb research about insect flight going on at universities, and some excellent books are available. Humans are getting close to being able to duplicate the aerodynamics of the bumblebee, but we are far from being able to provide the power and energy in such a small package.

5.09.01 Carl B Freeman asked:
In many projects they were looking for "extra lift." Have you considered filling the insides of some craft with helium to make them lighter? Inflatable craft would have simplicity and a strength from being "inflated."

McCready's response:
The Kremer Prize rules precluded the use of buoyancy gas. Our other planes would benefit very little from it, or in the end be hurt by the complexity and weight of sealing. At sea level, the lift of hydrogen in our biggest (over 200' span) plane might be 60 lbs, and it would take about 30 lbs of tape and seals to keep the gas, hydrogen or helium, in the wing, and add lots of complexity where spars or control lines enter and leave the wing. At 100,000 feet the lift would be under a pound (at 60,000 feet around 10 lbs), but cost the 30 lbs of extra weight of sealing. Also, the gas tends to leak through the plastic rapidly, quickly eroding any possible benefit.

5.09.01 Will asked:
I'm 16 years old and a private pilot and was wondering how does a model airplanes with the flapping wings thrust forward? Is it because of the air getting pushed around by the wings? Don't the planes shake themselves to pieces?

McCready's response:
In a moving canoe, put a paddle in the water with the blade parallel to the motion. As you move the paddle away from the boat (twisting a bit if necessary to avoid stall) it has a big lift force perpendicular to its direction of motion. Direction of motion in the fluid is say 30║ out away from the boat heading, so the lift, being 90║ from the paddle motion through the water, is 60║ relative to the boats heading which means thrust. Bring the paddle toward you, and again get the forward thrust. A bird╣s wing provides thrust the same way (except flapping up and down rather than sideways) with a bit of bias angle of attack to provide the average lift thrust keeps it aloft. The bird╣s body goes up and down a bit (but the head usually stays rather steady). Propellers make flight for humans comfortable and efficient. Birds, and all natural fliers, can't use rotary motion and so must get by on flapping.

5.09.01 Bill Havrilla asked:
There used to be a basic "starter" formula for concocting your own thin-film covering material for indoor flyers...seems like I recall it being made with a nitrocellulose base. Do you happen to know of any such animal or where I could look for it's "recipe"?
Thanks. ...nice episode

McCready's response:
Cruise the internet for books on model airplanes, especially indoor models. Here are some organizations/publications that are helpful.

The AMA and NFFS have good connections to indoor models. Academy of Model Aeronautics (and its official publication, Model Aviation, available at newsstands). An AMA membership gives you automatic liability insurance.

AMA address is
5151 East Memorial Drive
Muncie, IN 47302-9252
765-287-1256
Web site: www.modelaircraft.org.
AMA sells Detta Dart entry level kits, and videos, books and manuals.

Sailplane & Electric Modeler
P.O. Box 4250
W. Richland, WA 99353
509-627-0456.
Subscription $32/year
Web site: www.semodeler.com
e-mail: sailnelec@aol.com .

National Free Flight Society
3317 Pine Timbers Drive
Johnson City, TN 37604-1404
Web site:
freeflight.org

Radio Control Microflight
100 East Ridge
Ridgefield, CT 06877-4606

A book on the subject is "Indoor Flying Models" by Lew Gitlow, 1993. Lew Gitlow, Box 5311, Salem, OR 97304. $22 + $3 shipping.

5.09.01 Philip Greenwood asked:
Have you considered producing a "homebuilt kit plane" like a solar-electric Gossamer Condor?

McCready's response:
The Gossamer Condor was a very impractical plane made for one purpose win the Kremer Prize as quickly and cheaply as possible. It is large, cumbersome, can't be flown in wind above 4 or 5 mph, and is ready to break at any moment. There are more rewarding and safe hobbies to get into. The Solar Challenger was a successful solar electric plane, strong enough for turbulence but under-powered. At great expense its solar cells could only put out power equivalent to a medium size gasoline model airplane engine.

5.09.01 Robert Sterchak asked:
Dr. MacCready,
Last week I came up with an idea involving flying bird models. Viewing "flying Free", I see nothing quite like it. I have no resources to investigate patenting or development. Is it possible to send it to you to evaluate and see where it goes?
Thank you,
Robert Sterchak

McCready's response:
You can explore patents free on the Internet through the U.S. Patent and Trademark Office at www.uspto.gov. We don't have the time to examine and evaluate new ideas from outside. In fact we are too busy even to explore our own new ideas properly. Sorry.

5.09.01 Richard Trask asked:
Dear Paul,
I would like to try to build a small "flapping flyer" like the one that you demonstrated on the program. It was incredible the way it fluttered in a circular flight path. Is there any way that I could get plans for that design? I am quite skilled at making things, and would love to try it.
Thank you,
Richard Trask

McCready's response:
Its construction is very difficult and the plans give no details. Try the Internet for information on ornithopters. Also contact Industrial Evolution (indev.hypermart.net) for membership in the Ornithopter Society ($12/year).


back to top

return to show page

 


Is it a Bird?The Eternal WingEyes in the SkyTaking to the AirFlapping FlyersWalkalong Glider Teaching guide Science hotline video trailer Resources Contact Search Homepage