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Paul V. Cochrane
|II.||A General History of Events Which Led to Kitty Hawk|
|III.||A Discussion of Current Paper Airplane Books.|
|a. The Great International Paper Airplane Book.|
|b. The Paper Airforce.|
|c.The Ultimate Paper Airplane.|
|IV.||Flight. What Causes It?|
|V.||Four Quick Demonstrations For Use In The Classroom.|
|VI.||Some Sample Lesson Plans.|
|VII.||Paper Airplane Designs.|
A long time ago I had become interested in a TV series called Connections, hosted and written by James Burke. The premise of the show was that the events which have shaped and continue to shape our world are often the product of seemingly unrelated events, which eventually fall into place and lead to a great global change. Flight was one of these global changes. How would Burke have handled this topic? It’s my guess that it all started in the universal wishes of man to free himself from the chains of gravity, as evidenced in the myths of many cultures. From this starting point we would look at kites, the lateen sail, flight toys (old and new), hot air balloons, propulsion units, hang gliders, and the men who made them. Eventually we would end with the Kitty Hawk experience, the controlled flight of man in an aeroplane.
I think that all of my students could handle this part of the study of flight. The readings are fascinating and delightful. Within these readings are opportunities for experimentation, which can be done in the classroom.
As much as possible the classroom should be an experimental arena, a place where both the student and the teacher are involved, learning from each other. To read that the lateen sail enables a sailboat to move into the wind is not enough. Let us experience it. Get a shop vacuum (with its hose in the exhaust port), take some different diameter dowels, drill them, create a mast and a boom, make a triangular paper sail, glue it into place, and anchor all of this into clay or wood on top of a roller skate or toy truck and experiment, experiment, experiment!
There are a lot of good ideas out there, you just have to look for them. I know that planes fly because of the magnus effect, Bernoulli’s laws and the laws of Newton. I have been a passenger in several airplane flights, but it was not until I made an airfoil out of balsa wood and exposed it to a blast from my shop vacuum, and saw this “wing” rise, did I really believe it. Students are told this and that, all day long, they resent it. When they get a chance to “hands on” class work the class period does not drag and “we” learn more. Yes, our class will be louder than the one which is across the hall, but so what, we are learning out loud.
Some of the activities are complex, too complex for the slow student, so put him or her on some other task. Models which depict yaw, pitch and roll can be made to dress up the classroom. A working model of flight controls can be made by a student who is good with his hands. David Macaulay’s The Way Things Work is a wonderful reference book for this. Remember that the Wright brothers got their mechanical aptitude from mother (dad was an intense record keeper), so do not leave the girls out of the model making tasks.
When these and other activities have been done, I will introduce the class to four different paper airplane “texts”. Hopefully we will be able to understand some of the ideas we have learned in a “make and take home” series of lessons. I will start with the very pleasurable The Great International Paper Airplane Book and move on through to the complex and demanding Whitewings. The first book will be a “turn on”, I usually get questions like, “Will that thing really fly? You must be joking!”. The last book Whitewings will be a real work out, not just a cut, crease, tape and fly routine. The students will be required to read (with pencil in hand), work with formulas, and record data, cut, layer, glue, spray and then fly.
For a good many years man tried to fly like a bird, flapping his arms and feet and falling like a rock. It took some time for him to realize that this was a “dead end” pursuit. About 1700 hot air balloons became the toys of flight, and after a series of fires (burning straw was the balloon’s heat source and propellant), these ideas went into a temporary “limbo”. In 1776 Henry Cavendish, an English Chemist, isolated inflammable air, hydrogen, which had one-eleventh the weight of an equal volume of air. It is said that a professor at Glasgow University, Scotland, prepared a lesson to show that a vessel of hydrogen could rise from a table, but by the time he located a suitable container he was on a different lecture. So that demonstration was never made (to that class).
Before we can continue with our next “connections” we must mention the work and writings of Archimedes, 300 B.C. The following laws are the ones which interest us the most at this time. Any object suspended in a liquid or gas experiences an upward thrust (loss of weight) equal to the weight of the medium it displaces. A balloon, which contains one thousand cubic feet of air, would be subjected to an upward thrust of eighty pounds. If you can fill the balloon with some gas which is lighter than air then you could (if the quantities are enough to off set the weight of the balloon) achieve “lift off”. This sets the stage for the entrance of the brothers Montgolfier.
Legend has it that one day while drying his wife’s lingerie in front of a fire, Joseph Montgolfier took notice of how the fabric billowed. If this force could be contained in a bag, would it not lift things? He set about to experiment with this idea and he soon realized that this hot air could carry man aloft. Joseph wrote to his brother Etienne, (who had been educated as an architect and a mathematician) and told him to come home for they were going to do some wonderful experiments. These events came to brothers who were prepared to receive them, for their family was in the paper manufacturing business. Another link in a long line of “connections”.
The brothers worked together on researching buoyancy and making light weight frames and paper-lined cloth covering for their hot air balloons. This construction was not done in a random manner; Etienne made these very interesting observations, which were recorded in Gillispie’s The Montgolfier Brothers And The Invention Of Aviation, “The weight of an approximately spherical balloon is proportional to its surface and thus increases with the square of its diameter . . . The lifting force is proportional to the difference between the weights of the enclosed gas and of the displaced air. It is a function of the volume and hence the cube of the radius. Thus levity increases exponentially with size”. In June of 1783 the brothers, in full view of the public, launched a paper-lined hot air balloon, its heat source was a container of burning wool. The balloons diameter was 30 feet and it floated up to a height of six thousand feet and landed a mile away. The next launch carried some farm animals: a sheep, a duck and a rooster. Finally on November 21, 1783, two men, Francois Pilatre de Rozier and the Marquis d’Arlandes, floated into space. All of France rejoiced.
In the wings was one J.A.C. Charles, who was also interested in flight but in a different kind of a balloon. Charles had taken the experiments of Cavendish (chemist who had “discovered” hydrogen, a gas lighter than air) and was busy fashioning a balloon which could contain this new gas. His balloon was to be fabricated of a rubberized silk, through which the new gas could not pass. Ten days after the Montgolfier’s balloon flight, Charles publicly launched his two-man balloon. This balloon floated for two hours and landed twenty-seven miles away. On the second part of the flight, minus one man, this balloon rose to a height of nine thousand feet. Man was in the air to stay. His remaining problem was how to control the direction of the flight.
As a point of interest it should be noted that to generate the necessary amount of hydrogen, to fill a small balloon (12 feet in diameter) Charles had to mix 1000 pounds of iron filings with 498 pounds of sulfuric acid. Later balloons were to need more than ten times this amount.
Combinations of the two types of balloons met with disastrous results. Pilatre attempted to fly one such combination from France across the English Channel. With a crowd watching, the balloon (under hydrogen power) rose to a height of 6,000 feet. Pilatre needed more height so he fired off some straw, to generate hot air lift, there was an explosion and Pilatre’s name was entered into the record books for a second time.
1783—Montgolfier’s Hot-Air Balloon
If we look into Charles H. Gibbs-Smith’s text on Cayley we can read his long list of achievements or “firsts”. I will list a few more. First to realize that a cambered airfoil provides greater lift than a flat one, first to suggest an internal combustion engine for aircraft, and to publish these ideas. For a complete list I suggest that you read pages 201-204.
Among the many men who followed Cayley was a William Samuel Henson who in 1842 designed an airplane, not unlike Cayley’s design, which featured a vertical rudder, three wheels landing gear, a power-driven propeller, which could be placed in front or the back of the plane. The proposed craft never flew, because the steam engines of the day were just too heavy. By 1857 Felix Du Temple designed a craft whose wings were set in a V shape, this gave greater stability to the glider. This idea was proposed, demonstrated and published in 1808-1810 by Cayley.
In 1872 a brilliant but tragic figure came onto the scene, Alphonse Pénaud. Alphonse Pénaud designed the toy helicopter which one Milton Wright purchased and presented to his sons in the fall of 1878. Pénaud was also famous for designing another experimental model ( I would rather not call it a toy) which had a rubber band propulsion system and two fixed wings, a main wing and a tail wing (which was angled slightly down to give greater stability). In 1876 he designed a “joy stick” for glider which would control both elevation and direction. His next ideas were those of retractable landing gear, glass covering for the cockpit and propellers which were 66% efficient. Today’s propellers have an efficiency rating of about 85%. Pénaud had plans for a sea plane but lacked a suitable source of power. His design and plans were radical, his peers ridiculed him, unable to handle the pressure, at age 30 he put a bullet into his brain.
Pénaud’s Toy Plane
Our next important contributor was Otto Lillienthal (1848-1896), author of Bird Flight As A Basis Of Aviation who was deeply interested in flight. Lillienthal concentrated on how birds control their flight. Not wanting to stay in the abstract, Lillienthal used what he had learned and gave it concrete expression, the hang glider. These hang gliders were mostly monoplanes, with arched wings and a fixed tail. He learned to control flight by shifting his body, as the birds do, while in flight. His flights (over 2000 in number) were documented by photographs which were seen all over the world. Unfortunately Lillienthal’s hang glider stalled and he fell to his death from a height of 50 feet. News of his death sparked two men, who ran a bicycle shop, in America into action. Their name was Wright.
Lilienthal’s Biplane Glider (1895)
Our next distinguished guest was Samuel Pierpont Langley (1834-1906) noted engineer, scientist, and astronomer, head of the Smithsonian Institution in Washington, D.C. Working on a grant from the United States Governmenthe managed to produce two working, powered model airplanes. The first model had a steam engine, was launched from a catapult and flew for three quarters of a mile. The year was 1896. His next experiment was to use a gasoline engine in a model plane (then hopefully in a full-sized plane). He commissioned a Stephen Lytton to produce an engine. When completed it was radical (pistons radiated from center) in design, delivered 53 hp. and weighed 125 pounds. A quarter-size model flew beautifully, so work was begun on a full-size model which would be launched from the top of a house boat. Its pilot had never flown a glider or anything else. Two attempts at flight were made, both failed. Within ten days the Wright brothers would fly at kitty Hawk.
Wilbur (1867-1912) and Orville (1871-1948) Wright, were two men who ran a bicycle shop in Dayton, Ohio, and who were “turned on to flight” by their father, Milton, who had purchased a toy helicopter, designed by Alphonse Penaud (France). Their mother had great mechanical ability and their father was an avid record keeper. The brothers worked as one unit in all that they did. The news of Lillienthal’s tragic death triggered a renewed interest in flight in them. They searched everywhere for information which could help them learn about flight and flying. Once involved they experimented checked data, constructed instruments to measure flight (wind tunnel, gauges), made kites, gliders, finally gliders which could carry man and engine. These brothers were determined to draw information from any source, check it out, and then test it. If it was applicable it went into their work. They even worked on the gasoline engine which was to power their “glider”. It was no accident that they were the first. They armed themselves with all of the information of the day and then went to work to make that first flight possible. The brothers Wright did come up with some unique invention. They were superb flyers (of gliders) and were able to stabilize the flight of their craft by a process which had come to be known as wing warping. At this point I would like to add this information, Tom Crouch has written a wonderful book, The Bishop’s Boys, in which he covers the lives of his most unusual family, it’s a pleasure to read and reflect upon.
As a general wrap-up I would like to list some of the dates and names of the men who developed the power sources which were adapted to the space ships of the past. In 1852 Henri Giffard of France designed a 3.5 hp. engine which powered a 140 foot air ship. In 1872 Paul Haenlin of Germany piloted an airship using a 5.5 hp. hydrogen powered engine, which took its energy from its own balloon. A man named Ritchel invented a foot powered airship in 1878, it was not very good but it was an attempt. In 1883 Albert Gaston Tissandiers invented an electric motor capable of delivering 1.5 hp. to power his balloon. Europe was hard at work looking for a suitable power source for both balloons and gliders.
This first try at the paper airplane is designed to get the students involved. Its to be a “hook” to pull them in to doing things on their own. All lessons will be checked in the “book”, we are not here to waste time, all must participate. I will also do my best to expose the students to the rich humor of this book. I will read some of the contest letters to them including the one which is totally written in Japanese. I do have two favorite models which we as a class will do, they are #18, picked for its “far out” design and #8, which cries out “come fly me”.
I have included a copy of one of Vogt’s peace planes for you to see. Michael Vogt encourages the owner of this text to photocopy his plans. In this day and age that is an offer you rarely ever get. My students had a chance to show off their manual dexterity with Vogt’s planes.
Before we tackle any more questions it would be useful to look at our own encounters with air flow. We can wait for a hurricane or get into the family car to gather first hand encounters with the wind. Accelerate the car to 55 m.p.h. and put your hand out the open window, it may be presented to the air in one of three basic positions. First hold your hand parallel to the ground. The air should stream past in an even flow. Next tilt your hand up at about a 20 degree angle and your hand will rise quickly. You’re experiencing Newton’s law—action equals reaction. Your palm is hit by the air, which in turn “downwashes” and your hand rises for you have exposed more of its area to wind. You experience lift and an increased drag at the same time. The last position, hold your hand at right angles to the wind. Your hand is hard to control for it wants to move with the air stream to the rear, your getting a lot of drag, for you have exposed a maximum amount of area (palm) to the moving air.
We want an airfoil which will rise into the air and then level off into smooth flight. If we wanted to increase our rate of fall or had to stop quickly then we would present a lot of drag surface (palm) to the air stream. What we are discussing here are angles of attack (AOA). Angles at which an airfoil is presented to the airstream. An airfoil which is angled to the airstream would flip back causing a rotation along its longitudinal axis This prevented by the fuselage (which acts a a lever) and the tail wing. The tail wing falls in response to the rotation and becomes an air foil with a positive angle of attack so it rises, gets lift, and levels out the nose of the plane and settles back into a zero angle with respect to the oncoming stream of air. The plane then stabilizes itself into a level flight.
The next part of the discussion has to do the “boundary layer” which is best seen as part of visual example. Place a large telephone book on a table. Place one finger on the cut edge which is parallel to its spine and apply a gentle but firm pressure. The upper pages will slide quickly, the pages in the middle will move less rapidly and the bottom will stick to the desk top. According to Ludwig Prandtl (1875-1953) air on airfoil does much the same thing. The first layer which is in contact with the wing sticks there and does not move, except with the plane. About this first layer are a series of layers which make up a boundary layer. In this boundary layer air moves across the wing first in a laminar flow (steady) and finally as it proceeds across the wing changes into a turbulent flow. As each layer, which is within the boundary layer, gets further from the wing’s surface its speed accelerates until it matches the velocity of the airstream above. This laminar region thickness ranges from one tenth of an inch, at the leading edge, up to a few inches at the trailing edge. As air streams over this boundary layer it first encounters the region over the laminar part of the boundary layer where there is no friction. This changes when this air must stream over the turbulent part of the boundary layer where it encounters friction or drag. When a wing’s angle of attack is too great this boundary layer can no longer adhere to the wing, the wing loses its lift capability and the craft falls.
The trick is to design an airfoil which encourages laminar flow. In John Anderson’s Introduction To Flight airfoils standard and laminar are compared on pages 139-140 figures 4.34. The lift capability of the laminar design is clearly shown.
The Magnus effect was included to help us visualize the next theory on lift which is referred to as the circulation theory. The theory takes the Magnus effect and connects it to an airfoil, and mathematically it works. If the air flow is from the left, the circulation theory says that there is a closed curve which has a clockwise flow and moves with and around the airfoil. The clockwise flow moves down from the trailing edge compressing the air below causing pressure, continues on its way up over the leading edge, accelerating the on coming air, causing an enhanced lift. This, circulation, combined with an angle of attack and Bernoulli law is what causes lift and leads to flight.
This is an attempt to introduce the reader to some of the underlying ideas of flight, and the men who made it possible.
- 1. Drop the helicopter. Which way did it spin? What do you think caused it to spin? How would you reserve it spin? Have you seen anything in nature which spins like this? (Seeds from trees)
- 2. Cut off one half of a rotor (blade). Drop the helicopter. How does it behave. Cut the entire rotor off. What happens? If dropped up side down, what will happen? Try it.
- 3. Add weights to the helicopter and observe what happens (after dropping it). Try changing the lengths of the rotor, color the rotors for a patterned effect.
You will supply a suitable non-rectangular wing pattern, rulers, compass (for bisecting Tr and Tt). The students should understand that serious mathematics enters into any serious endeavor.
This book presents materials suitable for the classroom from the primary level up through junior high. Its filled with lots of ideas, experiments and things to do for all level of students.
Burke, James. Connections. Little Brown and Company. Boston, Mass. 1978. Here is a book for the more mature reader. The books theme is that great events are not random but depend on interconnected events. This is a great book which can be read in sections.
Crouch, Tom. The Bishops Boys. W.W. Norton & Co. New York, 1989 If you want many hours of pleasurable and fascinating reading about the Wright Brothers their family, work, dreams, it is all here in readable form.
Dalton, Stephen. The Miracle Of Flight. McGraw-Hill Book Company, New York. 1977. A wonderful book which studies, through photos, the flight of insects and birds and then ties them into aircraft. An informative book.
Dwiggins, Don. Riders Of The Winds. Hawthorn Books Inc.. New York, 1973. An easy to read book on ballooning.
Gillispie, Charles. The Montgolfier Brothers And The Invention Of Aviation. Princeton University Press, New Jersey. 1983. A well documented and interesting book on the earliest days of ballooning.
Kline, Richard. The Ultimate Paper Airplane. Fireside Book. Simon & Schuster, Inc.. New York. 1985.
Macualay, David. The Way Things Work. Houghton Mifflin Co., Boston, Massachusetts. 1988.
No school library should be without this text. The outside cover reads “A visual guide to the world of machines”, and that it is. You have to see this book to understand what a pleasure it is to read it. It would be impossible not to learn from this book.
Mander, Jerry.,Dipple, George, Gossage, Howard. The Great International Paper Airplane Book. Fireside Book. Simon & Schuster, Ind., New York 1967.
Niomiya, Yasuaki. Whitewings. A.G. Industries Inc., Yodogawa-Ku, Osaka, Japan. 1986.
Smith, A.G. History Of Flight Coloring Book. Dover Publications, Inc. New York, 1986.
Looking for good clear sketches of space machines? Look no further. A coloring book, suitable for the classroom bulletin boards and reports.
Vogt, Michael. The Paper Air Force. Contemporary Books. Chicago, Illinois. 1989.
Ward, Alan. Flight and Floating. .Osborne Publishing Ltd., London, England. 1981.
A wonderful little pocket book of information which tells us that it contains “save experiments to do at home”. I would add that this would be great for the non-motivated student, who has a short attention span. Very nice activities for all.
Weiss, Harvy. Sailing Small Ships Young Scott Books, New York, 1967.
Here is another nice book from the children’s section of the library. It contains a very nice section on buoyancy, and how weight and volume have to be considered. This is an informative and interesting book.
Wegener, Peter. What Makes Airplanes Fly? Springer Verlag, New York, Inc., (in press) 1990.
If you are looking for one text which contains the a great deal of information on flight, here it is (for the serious student and teacher).
Aviation Education Source Book. The School of Education, Stanford University. Hastings House, Publishers Inc., New York. 1946.
Burke, James. Connections. Little Brown and Company. Boston, Massachusetts. 1978.
Crouch, Tom. The Bishop’s Boys. W.W. Norton & Co., New York, 1989.
Gibbs-Smith, Charles. Sir George Caylay’s Aeronautics. Her Majesty’s Stationary Office. London, England. 1962.
Gillispie, Charles. The Montgolfier Brothers and The Invention Of Aviation. Princeton University Press, New Jersey. 1983.
Dalton, Stephen. The Miracle Of Flight. McGraw-Hill. New York. 1977.
Kline, Richard. The Ultimate Paper Airplane. Fireside Book. Simon & Schuster, Inc. New York. 1967.
Macaulay, David. The Way Things Work. Houghton Mifflin Company, Boston, Massachusetts. 1988.
Mander, Jerry., Dipple, George., Gossage, Howard. The Great International Paper Airplane Book. Fireside Book. Simon & Schuster, Inc. New York. 1967.
Ninomiya, Yasuaki. Whitewings. A G Industries Inc. Redmond, WA. 1986.
Vogt, Michael. The Paper Airforce. Contemporary Books Chicago, Illinois. 1989.
Wegener, Peter. What Makes Airplanes Fly?. Springer Verlag, New York, Inc. (in press) 1990.
Contents of 1990 Volume VII | Directory of Volumes | Index | Yale-New Haven Teachers Institute