Smithsonian in Your · PDF fileSmithsonian in Your Classroom How Things Fly September/October...

InsideLesson PlanTake-HomePages inEnglish/Spanish

SubjectsMathScience

Grades4–9

Publication ofthis issue ofSmithsonian inYour Classroomis made possiblethrough the generous support of thePacific MutualFoundation.

September/October 1997

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HOW THINGS FLYActivities for Teaching Flight

ave you ever dreamed of flying? As a child, you may have run full speedwith your arms stretched and flapping, hoping that—just a little faster—you could take off. Most of us, including your students, have probably had these dreams. This issue of Smithsonian in Your Classroomembraces

that spirit of adventure and discovery by having students draw upon their own experiences and sense of movement to understand the basic physics of flight.They’ll even learn that they can fly, if only for a moment at a time. The lessons and activities in this issue of Smithsonian in Your Classroomhave been adapted

from classroom-tested materials developed bythe education department of the Smithsonian

Institution’s National Airand Space Museum.

New name, same great content! Art to Zoo: Teaching with the Power of Objectshas a new name, Smithsonian in Your Classroom: Lesson Plans from Art to Zoo.

Smithsonian in Your Classroom’s purpose is to help teachers bring into their classrooms the educational power of museums and other community resources. Smithsonian in Your Classroomdraws on theSmithsonian’s hundreds of exhibitions and programs—from art, history, and science to aviation and folklife—to create classroom-ready materials for grades four through nine. Each of the four annual issues explores a single topic through an interdisciplinary, multicultural approach. The Smithsonian invites teachers to duplicate Smithsonian in Your Classroommaterials for educational use.

You may request a large-print or disk version of Smithsonian in Your Classroomby writing to the address listed on the back cover or by faxing your name, school name, and address to (202) 357-2116.

HC o n t e n t s

Lesson Plan Step 1 p 3



Activity Set 1 p 6

Activity Set 2 p 8

Take-Home Pages A-D p 1 1

Resources p 1 5

In this lesson, you’ll introduce your students to the four forces of flight—drag, lift, thrust, and weight—through a variety of fun-filled flight experiments. Students will “fly” for short periods and then evaluatefactors that might either increase or decrease their “flight” duration.

You might begin the activity by asking your students the following questions:■■ Can you fly? How high do you think you can fly? How long do you think a very good jumper (e.g., Michael Jordan) can stay in the air?■■ Have your students complete the “How HighCan You Fly?” and “How Long Can You Fly?”activities on page 6. Ask them to examine theduration and height of their flights. Are they surprised at the results?■■ Refer to the “Think About It” activity on page 6. Ask your students to observe each of thecartoon figures. What are they doing? How mightthe cartoon figures’actions and environmentsallow them to jump higher and for longer periodsthan anyone in class? What else could students do to make their jumps last longer?

Smithsonian in Your Classroom How Things Fly September/October 19973

LESSON PLAN Step 1Look Mom, No Wings!

Possible observations of the cartoon figures

Parachute figure—This figure can stay airbornelonger because the parachute slows the person’s fall.Demonstrates drag.

Helmeted figure—This figure can jump higherbecause the sleek helmet decreases air resistance.Demonstrates drag.

Figure with springy shoes—This figure can jumphigher because the springy shoes provide a powerboost. Demonstrates thrust.

Moon-walking figure—This figure can jump higheron the Moon than on Earth. The smaller gravity onthe Moon means that the figure weighs less there.Demonstrates the force of weight.

Figure with propeller hat—The spinning propellercreates a difference in air pressure, which pushes the figure upward. Demonstrates lift .

Definitions

Drag—The resistancecaused by the shape of anobject and its movementthrough the air.

Lift—The upward forcecreated by a difference inair pressure. Moving aircreates this difference asit moves around an airfoil(e.g., a wing).

Thrust—The force developed by a propelleror jet engine that drivesan airplane through theair. (In the jumping activity, students’legmuscles provided thrust.)

Weight—Ameasure of the heaviness of anobject.

Direct your students tothe “What’s Going on?”section on page 7. (Youmay wish to have severalstudents alternately readthis section to the class.)Conclude the activity byreinforcing the conceptthat on Earth four forceswork together to makethings fly: thrust, drag,weight, and lift.

Some other possibleactions to make jumpslast longer

Lift—Wear wings.

Thrust—Jump off a tram-poline or diving board;launch yourself with apole vault, catapult, orrocket; or exercise to getstronger muscles.

Weight—Wear lighterclothing, lose weight, ortravel to a planet withsmaller gravity thanEarth’s.

Drag—Wear skin-tightclothing.

Students may suggestother methods to maketheir jumps last longer.You may wish to organizetheir thoughts by drawinga simple chart on thechalkboard (see below).

Drag

Thrust

Lift

Flight

In this lesson your students will conduct aseries of hands-on experi-ments that will help themto understand the role oflift in fixed-wing flight.Students will observe theflow of air and wateraround several surfacesand then consider thedynamics of airflowaround an aircraft wing.

You may wish to beginthe activity by tellingyour students that,although air is invisibleto the human eye, it ismade up of physical matter—real “stuff.” Thismeans that air exerts aforce that helps to keepan airplane up in the air.

Tell your students thatthe experiments in thislesson will demonstratewhat Swiss mathemati-cian Daniel Bernoulli discovered in the early1700s: When flowing airor water changes speed,its pressure also changes.

With each activity, askyour students to considerwhat is going on. Is air

slowing down or speed-ing up? How might airpressure be changing?How might the flow ofair (and its changingpressure) help to keep anaircraft up in the air?

Direct your students tothe “Use Your Lips toLevitate” and “BalloonsThat Boggle” activitieson page 8. What happenswhen air is blown overthe paper or between theballoons? Ask studentswhat they think causesthe paper and balloons to move.

After your studentshave finished the activi-ties, direct them to the“What’s Going On? TheSimple Explanation” section on page 10. (Youmay wish to have severalstudents alternately readthis section aloud.) Usethe questions in the textas the basis for a classdiscussion. Be sure thatstudents understand thatair loses pressure when it speeds up.

Ask your students tobegin the “Squeeze theStream” activity. Explainthat this activity is morecomplex than the previ-ous two activities and will

require teamwork. (Youmay wish to have three orfour experiments goingsimultaneously, so that allstudents can observe thewater movement first-hand.) Stress thatalthough this experimentuses water, air flows in asimilar manner.

Direct your students tothe “What’s Going On?The AdvancedExplanation” section onpage 10. (You may wishto have several studentsalternately read this section to the class.)Conclude the activity byreinforcing these impor-tant concepts: (1) Airspeeds up as it movesaround an object. (2)When air moves faster,its pressure drops and itpushes less. (3) When anairplane flies, air speedsup more above the wingthan below it. As a result,the air above an airplanewing pushes less than theair below the wing. Thehigher pressure below thewing pushes the wing(and the airplane) up.

4 Smithsonian in Your Classroom How Things Fly September/October 1997

LESSON PLAN Step 2Bernoulli Brain-Teasers

In this lesson, your students will observe photographs of selectedtwentieth-century aircraftat the National Air andSpace Museum and notedifferences in the designof aircraft wings, fuse-lages, and engines.

Begin the activity bytelling your students thatthey’ll be looking at photographs of twentieth-century aircraft at theSmithsonian’s NationalAir and Space Museum inWashington, D.C. Stressthat these photographswill help them to under-stand some of the manyapproaches to aircraftdesign.

Direct your students tothe Take-Home Pageactivity on pages 11–14.(Depending on time andresource availability, youmay complete the lessonas either a take-home orin-class activity.) Tellthem to observe carefullyeach aircraft. How are thewings shaped? How is theaircraft’s body (fuselage)shaped? What type ofengine does the aircraftappear to have? Is there any evidence ofstreamlining(designingthe body of an aircraft sothat it moves easilythrough the air)?

After your studentshave completed theirobservations, begin a classdiscussion about theirfindings. Ask them to consider if any of the air-craft display evidence ofstreamlining. Answersmay vary, but studentswill probably note thewheel coverings andengine cowling of theVega as well as theretractable landing gearand long, narrow fuselagesof the 727 and the X-15.

Next, direct your stu-dents to a comparison ofthe X-15 and the Vega.How do their wings dif-fer? Students will proba-bly conclude that the X-15has shorter, thinner, andmore swept back wings.Emphasize that airplanesdesigned to fly faster thanthe speed of sound usewings like these to reducethe substantial force ofdrag in supersonic flight.

Conclude the activityby asking your students toevaluate the type of mate-rials used in each aircraft.Students will likely con-clude that cloth, wood,and metal have been usedin the example aircraft.Emphasize that the choiceof materials dependslargely on the desiredspeed and performance ofan aircraft and that each

plane featured in the activ-ity was designed aroundthe engine power availableduring the time when itwas built.

Stress that the WrightBrothers chose largewings and a lightweightframe for their Flyer to compensate for theirrelatively weak engine.Alternately, the designersof the Vega concentratedon reducing drag byremoving wires and strutsand encasing a much morepowerful engine within astreamlined cowling.

The high-powered jetengines available by the

1960s allowed the engi-neering team of the Boeing727 airliner to use high-strength materials and thin,swept-back wings thatreduced drag and increasedspeed to nearly 600 miles per hour.

Engineers at theNational Aeronautics andSpace Administration(NASA) who worked onthe X-15 project had evenmore available power in the form of rocketengines. The focus of their experimental workwas to develop the highlystreamlined fuselage, shortwings, and heat-resistantmaterials necessary forsupersonic flight.

LESSON PLAN Step 3Flying through Time

Some possible aircraft observations (For more detailed information on each aircraft, referstudents to a school or local public library or to theNational Air and Space Museum’s World Wide Web site,http://www.nasm.si.edu.)

Wright Flyer (1903)—two wings (biplane), woodenframe with stretched fabric, small piston engine, pilotlies on wing, no landing gear, two propellers

Vega (circa 1930)—single wing (monoplane), tapering wooden fuselage, fixed landing gear, engine in front, streamlined covering (cowl) over engine, wingover cockpit

Boeing 727—(first produced in 1964 and still in service)— swept-back wings, retractable landing gear,three jet engines attached to tail of aircraft, streamlinedmetal fuselage, large in size.

X-15 (circa 1960)—fuselage shaped like a rocket,rocket engine at the back of the aircraft, short wings.

HOW HIGH CAN YOU FLY?

Materials■ Large sheet of paper■ Tape■ Dirt or stamp pad■ Ruler or meter stick

How high do you thinkyou can you jump? Getsome of your friendstogether to find out.■■ Tape a large piece ofpaper to the wall. (Brownwrapping paper or sheetsof newspaper will do.)The shortest person inyour group should beable to reach the bottomof the paper withoutstanding on tiptoes.

■■ Dip one finger in dirtor ink. While standingwith your feet flat on thefloor, stretch your arm asfar as you can and markthe highest point you canreach on the paper.■■ Now jump and markthe paper by touching itat the top of your jump.Try it a few times andchallenge your friends tojump higher. (Label eachperson’s standing andjumping marks with ini-tials or have each personuse a different color ofink or dirt.)■■ Use a ruler or meterstick to measure the ver-tical difference in heightbetween your standingand jumping marks. Thisis how high you canjump. Surprised?

HOW LONG CAN YOU FLY?

Materials■ One helper■ Stopwatch or watchwith a second hand

How long can you stayin the air when youjump? Ask someone totime you with a stop-watch or a watch with asecond hand. (It won’t beeasy!) You can also timejumping athletes who areplaying sports such asbasketball or volleyball.

THINK ABOUT ITThese characters can jump higher and longer than youcan. What are they doing that makes a difference? Whatelse could you do to jump higher or make your jumplast longer?


ACTIVITY SET 1Look Mom, No Wings!

Do you ever dream of being able to fly? The goodnews is, you probably can! The bad news is, youcannot fly very high or stay up very long.

WHAT’S GOING ON?You probably noticed

that taller kids didn’t nec-essarily have higherjumps. Remember, youmeasured the jump heightfrom your reach (thestanding mark) and notthe ground. The bestjumpers in the world canclear heights up to 2.4meters (8 feet), but theylift their center of massconsiderably less thanthat distance.

Did you have a hardtime measuring your timein the air? You’re notalone. Even the bestjumper remains airbornefor less than one second.Still, you can computeyour airborne time byusing the table below.Look down the first col-umn for your jump heightand read across to findyour time.

Is jumping really flying? Yes and no. Some things like rock-ets, cannonballs, andbaseballs fly like jumpingkids: They are pushedinto the air by engines ormuscles. Airplanes aremore complex: Enginespush them forward, andair pushes and holdsthem up.

Thrust, drag, weight,and lift are the fourforces that work togetherto make things fly. Youalready know somethingabout each of them,although you might nothave called them by theirnames. If you thoughtthat having stronger mus-cles, springy shoes, or arocket booster might helpyour jump, then you werethinking about thrust (theforce that pushes youduring flight). If you

thoughtthat a slicksuit or helmet wouldmake you jump higher orthat a parachute wouldkeep you in the airlonger, then you werethinking about drag (theresistance of air againstthings that fly). If youthought about jumpinghigher by losing weight,changing clothes, or visit-ing the Moon, you werethinking about weight(the force that holds youto the ground).

Most people haveexperienced how thrust,drag, and weight can helpthem jump higher, or“fly ,” but few people arefamiliar with lift. Lift is apush that comes from theair. You were thinkingabout this force if you

decid-ed that

wearingwings or

holding helium balloonswould help you jumphigher. While planes andbirds have to be movingto get enough of thispush to fly, hot-air bal-loons are light enough for their size that the airwill lift them up whetheror not the balloon ismoving.

Does everything thatflies use all four forces?Nope. Only two forces,weight and thrust, act onspacecraft. Lift and dragare not factors in space-craft flight, because thereis no air in space.

This was a quickoverview of the forces offlight. Don’t stop here,though. Ask your teacherfor help in finding moreinformation about howhigh you can fly.


Jump Height Time in Air(centimeters) (inches) (seconds)

25 10 0.4

50 20 0.6

75 30 0.8

100 39 0.9

USE YOUR LIPS TO LEVITATE

Materials■ Piece of paper

Hold a piece of paper between your thumband forefinger, as shown in the picture below.Now blow over the paper. What happens?

ACTIVITY SET 2Bernoulli Brain-Teasers

To pilots, lift means the way that airholds up airplanes and other flyingobjects. These activities will show youhow this force works—and they don’trequire a pilot’s license.

BALLOONS THAT BOGGLE

Materials■ Balloons■ String■ Water

Try this activity with a friend. Blow up two balloonsand tie each one to a string. Hold the balloons a fewinches apart and try to blow them together. Can you do

it? What happens? Try different ways ofblowing on the balloons to see what

happens. (Hint: Squirt a little waterinto the balloons before you blowthem up. This will help steady them.)


SQUEEZE THE STREAM

Materials■ Cookie sheet■ Pencils■ Tape■ Plastic wrap■ Sink or tub■ Water■ Small scraps of paper or Styrofoam (optional)

Fluids, such as air and water, change speed asthey flow between and around objects. To see howthis happens, build a tiny stream channel. Tape

pencils to a cookie sheet so that they make achannel that starts out wide and then narrows.

Drape the pencils and cookie sheet with plas-tic wrap; this creates a waterproof channel.Now barely tilt the cookie sheet againstthe sink and slowly pour soapy water intothe channel. Does the speed of the waterchange? How? When? (Hint: You may

want to add small scraps of paper orStyrofoam to the water to help you observe the

current’s flow.)

SO WHAT’S A BERNOULLI?In the early 1700s, a Swiss mathematician named

Daniel Bernoulli discovered that when flowing airor water changes its speed, its pressure alsochanges.

As you do these activities, can you figure outhow the pressure changes? How does this help airplanes stay in the air?

WHAT’S GOING ON?

The Simple Explanation…Air is pretty pushy stuff. It never pulls or sucks;

it pushes. Air is pushing on you right now from everydirection. We’re so used to air being around us that weoften don’t notice it. This constant push of air is calledair pressure. It allows us to breathe—not a bad thing!Now think about what was happening in the activitiesyou just finished. Why did the balloons come togetherwhen you blew between them? Why did the paper liftup when you blew over it? Air must be pushing thesethings, but how?

Even before you blew at the balloons, they were surrounded by air pressure. If you tried blowingbetween them, you disturbed this push in a very specialway. How? Think about this: Either the air between hasstopped pushing as hard or the air on the outer sides ispushing harder. Which do you think happened? Whichair did you disturb, the air between the balloons or onthe outer sides of the balloons?

Can you figure out what happened with the paper?Now you know that the paper was surrounded by airpressure. How did you change the air when you blewover the paper? Remember, air can’t suck up anything,but it can push. Did you change the push of air on thetop or the bottom of the paper?

Okay, enough questions! Here’s what was going on:In both the balloon and paper activities, air lost pressureand stopped pushing as hard. This happened becauseyou blew the air, and it had to “squeeze” between oraround the objects. As it “squeezed” through, it sped up, lost pressure, and stopped pushing as hard.

The Advanced Explanation...Now that you know about push and lift, can you see

how these forces might relate to airplanes? If we canmake air speed up over a wing, the pressure of the airover the wing will drop. The higher pressure air belowthe wing then pushes the airplane up. How would youshape a wing so that the air moves more quickly overthe top than under the bottom?

The “Squeeze the Stream” activity shows what happens when a fluid is forced to flow from a widespace through a narrower channel. For the water tosqueeze through a thinner space, something must eithercompress the water (think of pulling a sponge through abottle neck) or speed it up. Freely flowing water doesnot compress easily. Instead, it speeds up as the channelnarrows. Water also speeds up as it moves around anobject, such as a rock in a river. Air is a fluid, too, andit behaves like water when it moves through a narrowchannel or around an object: It speeds up. As you sawwith the other activities, when air moves faster, its pressure drops and it pushes less.

When an airplane flies, it pushes air out of the way.That air must go somewhere—so it “squeezes” betweenthe wings and the surrounding air. The wings areshaped and tilted so that the air moving over the top has less room than the air moving below the wings.Because it has less room, the air moving over the topmust speed up more than the air below the wing. As it


moves faster, the air on top of the wing also loses pressure and push. The slower moving air below thewing maintains more of its pressure, which pushes the wing, and the plane, up.

An airplane wing affects moving air much like a rockin a stream affects moving water. Remember that thespace around the wing is already jammed full of air, sothere’s no empty space for more air to move into. Asoncoming air hits the wing and moves either over orunder it, it speeds up and “squeezes” between the wingand the surrounding air.

The Wrong Explanation...Many books state that air speeds up over a wing

because it has further to travel than air moving underthe wing. This explanation implies that air separates atthe front of the wing (point A) and rejoins behind thewing (point B), but this isn’t true. Air moving over the top of a wing speeds up so much that it arrives atpoint B sooner than air that travels beneath the wing.

Lift

A

B

Movementof aircraft

Airflow thatspeeds up more

Airflow thatspeeds up less

A


TAKE-HOME PAGETRABAJO PARA HACER EN LA CASA

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Observe and Describe Observa y Describe

Aircraft body (fuselage) El cuerpo de la aeronave (el fuselage)

Wing shape La forma del ala

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Streamlining La aerodinámica de la nave



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sta publicación ha sido posible gracias al generoso aporte de la Pacific M

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RESOURCES

BOOKS AND TEACHING GUIDES

Blackburn, Ken, and JeffLammers. The WorldRecord Paper AirplaneBook.New York:Workman, 1994.

Doherty, Paul, Don Rathjen, andExploratorium TeacherInstitute Staff. TheSpinning Blackboard and Other DynamicExperiments on Forceand Motion. New York:John Wiley, 1996.

Epstein, Lewis Carroll.Thinking Physics:Practical Lessons inCritical Thinking,Gedanken Physics. San Francisco: InsightPress, 1994.

Flight. Alexandria, Va.:Time-Life Books, 1990.

Jakab, Peter L. Visions ofa Flying Machine: TheWright Brothers and theProcess of Invention.Washington, D.C.:Smithsonian InstitutionPress, 1990.

Jennings, Terry J. Planes,Gliders, Helicopters, andOther Flying Machines.New York: LarousseKingfisher Books, 1995.

Lopez, Donald. Flight.Alexandria, Va.: Time-Life Books, 1995.

Oakes, Claudia M., and Kathleen Brooks-Pazmany. Aircraft of theNational Air and SpaceMuseum. Washington,D.C.: SmithsonianInstitution Press, 1992.

Smith, H.C. IllustratedGuide to Aerodynamics.2nd ed. Blue RidgeSummit, Pa.: TAB Books, 1992.

The Visual Dictionary ofFlight. New York:Dorling Kindersley, 1993.

PERIODICALS

AIR & SPACESmithsonian, a bi-month-ly magazine, containsarticles and features ofinterest to air and spaceenthusiasts, laypersons,and professionals. To subscribe, write to Air & Space, P.O. Box53261, Boulder, CO80322–3261, or visit theAIR & SPACESmithsonianonline site at http://www.airspacemag.com.

ELECTRONICRESOURCES

These comprehensivesites provide links tohundreds of the majoraviation-related pages onthe World Wide Web.

National Air and Space Museumhttp://www.nasm.si.eduThe Smithsonian’sNational Air and SpaceMuseum features online

exhibitions (including theHow Things Fly Gallery)as well as links to manyof the sites below.

The Air Affairhttp://www.airaffair.com/hotlist.html

Aviation Laboratorieshttp://www.avlab.com/link.html

Embry-RiddleAeronautical Universityhttp://macwww.db.erau.edu

Landings: Aviation’sBusiest Hub inCyberspacehttp://www.landings.com/aviation.html

Michele’s Virtual Hangerhttp://rampages.onramp.net/~micheleb/hanger.html

ACKNOWLEDGEMENTS

National Air and Space MuseumBarbara BrennanClare CuddyDavid Romanowski

PHOTOGRAPHS

All photographs in thisissue are from the collec-tions of the National Airand Space Museum.Images copyrightSmithsonian Institution.

ILLUSTRATIONS

Cover, page 6Chris Major

Page 10Alan Smigielski

Pages 2, 15Stan Stokes, courtesy ofNASA Dryden FlightResearch Center

SMITHSONIAN IN YOUR CLASSROOM

Smithsonian in YourClassroomis a publica-tion of the SmithsonianOffice of Education,Smithsonian Institution,Washington, DC 20560.

WritersCarolyn BalchAlan Smigielski

EditorDouglas Casey

TranslatorSarita Rodriguez

DesignerKarlic Design AssociatesBaltimore, Maryland

Publications DirectorMichelle Knovic Smith

ONLINE LESSON PLANS

This and other publica-tions are also availableelectronically over theWorld Wide Web(http://educate.si.edu).Look for more informa-tion on Smithsonian electronic educationalservices and publicationsin future issues of Smithsonian in YourClassroom.


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