Looking At Airplanes Visitor Guide (PDF)

StreamliningPays OffNOTICE the Vega’ssmooth, rounded fuselage.The exterior skin is moldedplywood glued to an internalframe.This construction strengthened the fuselage, because boththe skin and the internal frameprovided structural support.Compare the Vega’s fuselage withthe boxy shape of the Spirit’s.Which looks more streamlined?LOOK for other streamlining features on the Vega.The Vega has a “cowling” or coveron the engine and “wheel pants”on the landing gear.These aloneMILESTONES OF FLIGHTYou canview thisairplanefrom thislocationon thesecondfloor.XStand here to view airplanePIONEERS OF FLIGHTPAGE10added 32 kilometers (20 miles) perhour to the airplane’s maximumspeed.The Vega’s wing—bracedinside and stronger than theSpirit’s—does not have externalsupports or “struts.” And the Vega’srounded fuselage reduces windresistance (drag) too.THINK further:Why wasstreamlining important forthe Vega?An important clue lies in the Vega’s450-horsepower engine. It wastwice as powerful as the Spirit’s, yetits maximum speed is only 96kilometers (60 miles) per hourmore than the Spirit’s. Additionalspeed means an airplane can liftmore weight, but extra speed alsoincreases wind resistance, or drag.Increased drag slows the airplanedown and uses up fuel.Think ofathletes who wear streamlinedclothing to reduce drag.READ about a manahead of his time.Jack Northrop always had his sightsset on the future. As he developeddesigns to solve problems for awood-framed Vega, he wasexploring techniques for buildingaluminum airplanes. Perhaps most

1900191019201930194019501960 This Airplanein TimeCowlingFuselageWheel Pantsrevolutionary was his design in thelate 1920s for a “flying wing.”Northrop presented his ideas tothe U.S. Army Air Corps, but theairplane wasn’t developed becauseit had a seemingly unsolvableproblem with pitch control. Withthe advent of computer-controlledflight, the Air Force again becameinterested in his plans. Before hedied in 1987, Northrop was invitedto the unveiling of the B-2 stealthbomber—a “flying wing” basedupon his designs. Pictured above isthe Northorp NM-1 that wasdeveloped in 1940 and is in theMuseum’s collection.Lockheed VegaAmelia Earhartowned this Vegabetween 1930and 1933. Sheflew it solo acrossthe United States and then acrossthe Atlantic. It is one of 130 thatwere built, establishing the Vega asone of the first commercialsuccesses in aviation.During the late 1920s and early‘30s, Vegas had a reputation forbeing reliable and efficient.Adventurers used them to set speedand distance records and to explorethe globe. Many transportationcompanies used them because theairplane could carry up to fourpassengers as well as heavy bulkycargo. Much of the Vega’s success isdue to designer Jack Northrop. Hedevised construction techniquesthat strengthened the fuselage forcarrying more weight and openedup its interior for better use of thespace. He also streamlined theVega, which contributed to itsoverall performance.PAGE11

Why Does ItLook Modern?RudderIDENTIFY the featuresthat make this airplanelook like modern passengerairplanes.It has a large fuselage with windows, large wings, and large twinengines.The shape of the fuselageand other surfaces are streamlined.And it is made of aluminum!AileronSpirit and the wood construction ofthe Vega) could have a larger fuselage and larger wings and thereforecould carry more weight.further:What’s sogreat about aluminum?NOTICE the rivets on theIt is stronger and lighter thanwood. An aluminum airplane(unlike the mainly wood and fabricconstruction of the Flyer and theThe aluminum skin was attachedwith rivets to an internal aluminumframe. Just like the Vega, the external skin and the internal frameboth provide support and add tothe airplane’s strength.THINKAIRTRANSPORTATIONTEST YOURSELF ! MILESTONESOF FLIGHTfuselage and the wings.THINK about why theDC-3 looks the way it does? Why are the wings so large? Theyprovide lift for the heavy cargo, passengers and fuel the DC-3 typicallycarried on long-distance flights.Escalator Why are all the surfaces rounded?XStand here to view airplaneYou can view this airplanefrom this location on thesecond floor.PAGE12PIONEERSOF FLIGHTThe 1,200-horsepower engines provided a cruising speed from 248 to304 kilometers (155 to 190 miles)per hour, so drag reduction wasimportant.The DC-3 has a roundedfuselage, a smooth, curved areawhere the wing is attached to the

1900191019201930194019501960 This Airplanein TimerRivetsRivetsfuselage, cowlings surrounding theengines, and retractable landing gear. Find the control surfaces used on theDC-3.The rudder, elevator, andailerons are located similarly to theSpirit and the Vega.The aileronsextend across a large portion of thewing.This gives extra control in theroll axis.IMAGINE taking a flighton the first DC-3.It is June 1936.This first model isoutfitted as a luxury sleeper.Thereare seven upper and seven lowerberths.You board in New York at6 p.m. with a friend, comfortableclothes, a toothbrush, and yourfavorite pillow. After dinner, you settle into your berth and close youreyes. Before you know it (unlessyou were awakened by the threeor four refueling stops), it is 10 a.m.,and you are landing in Los Angeles.How far can you travel today in 19hours on a large jetliner?Douglas DC-3The DC-3 becamea legend in itsown time. Theairplane’sstrength and reliabletwin engines made it an industryfavorite. By 1938 the DC-3 handled most of the nation’s airlinetraffic and assured the commercial success of passenger service.The DC-3, or “Gooney Bird”as it was affectionately nicknamedduring World War II, typicallycarried up to 21 passengers. It wasknown for providing a smooth,quiet ride over long distances atan impressive speed of 288kilometers (180 miles) per hour.Thousands of DC-3s were built,and the resulting growth in passenger travel created profits forthe airlines for the first time.There are still 400 DC-3s inservice today.PAGE13

Jet Power!SEE how a typicaljet engine works.FIND the engineson the XP-59A.There aren’t any propellers. A jetengine works on a different principlethan a piston engine. A piston engineand propellers generate thrust bycreating differences in air pressurearound the propellers. A jet engine’sburning fuel sends gases out theback of the engine with such forcethat the airplane is thrust forward.The same principle explains themovement of a balloon if it is filledwith air and then let go.Try it whenyou get home!MILESTONES OF FLIGHTYou canAir is drawn into the front of theengine, compressed by spinningblades, and forced into a combustion chamber. In the chamber, theair mixes with fuel and ignites in acontinuous burn.The gases blastout of the back of the engine withtremendous force.The equal andopposite reaction thrusts theairplane forward.view thisTEST YOURSELF!from thisCOMPARE the wings oflocationthe Spirit,Vega, and DC-3with those of the XP-59A.Why does the XP-59A havea thinner wing? airplaneon thesecondfloor.XStand here to view airplanePIONEERS OF FLIGHTPAGE14A main benefit of the jet engine isincreased speed.The XP-59A’s560 kilometers (350 miles) perhour increased the lifting ability ofthe wing, so less wing area was

1900191019201930194019501960 This Airplanein TimeAir Intakeneeded.The increased speed alsoincreased drag. A thinner winghelps reduce drag.LEARN more.Try to find the combustion chambers on the piston, jet, and rocketengines in the How Things Fly gallery.The XP-59A was constructed in greatsecrecy. The United States was unawarethat Germany had jet airplanes readyfor combat, so elaborate precautionswere taken to avoid spying. While theairplane was being tested in Muroc DryLake, California, officials disguised theXP-59A’s jet technology by attaching afake propeller to its nose.Bell XP-59AAiracometThe XP-59A is thedirect ancestorof Americanjet-propelledairplanes. It wascommissioned in 1941 by theChief of the Army Air Forces. Theairplane never entered combat,but it provided training for ArmyAir Forces personnel and valuabledata for the development ofhigher-performance jet airplanes,including contemporary jetliners,which can carry 400 passengers at800 kilometers (500 miles) per hour.The “X” in its name means itis an experimental airplane. Whenthe Army Air Forces ordered itsdevelopment, there was hope thatjet technology would evolve fastenough to support U.S. efforts inWorld War II. That did not happen. Even so, the XP-59A revealsbasic features of a jet airplane.PAGE15

Speed FasterThan SoundNOTICE the sleekfuselage, skinny nose, andshort, thin wings.At the speed of sound, a secondkind of drag—caused by shockwaves—affects how the airplanemust be designed.These are threemajor features on the Bell X-1 thathelp diffuse shock-wave drag.FIND the engine: Do yousee openings for drawing inair like a jet engine?There are no openings for air.TheBell X-1 is powered by a rocketengine. Like a jet engine, a rocketengine burns a mixture of fuel andMILESTONES OF FLIGHTYou canview thisairplanefrom thislocationon thesecondoxygen. Unlike a jet, a rocketcarries its own oxygen, usually inliquid form.The exhaust gases thatrush out the back of the rocketexert pressure on the internal surfaces of the rocket engine, whichpushes the rocket forward. It iseasy to tell the difference betweena jet and a rocket engine: a jetengine has an opening for air intakebut a rocket engine does not.SEPARATE the rocketsfrom the jets.From the middle of the secondfloor balcony, identify two otherrocket-propelled airplanes and twojet airplanes.The rocket-driven airplanes, in addition to the Bell X-1,are the black North AmericanX-15, hanging in the Milestones ofFlight gallery, and the white DouglasD-558-2 Skyrocket, to the right ofthe X-15 and hanging above theescalator.The jet airplanes you cansee are the XP-59A, which we’vealready discussed, and the LockheedF-104A Starfighter, which is hangingto your left by the Planetarium.floor.XStand here to view airplanePIONEERS OF FLIGHTPAGE16READ what the pilot said.You can find the control surfaces forall three axes on the Bell X-1. Butduring the time Chuck Yeagerwas its test pilot, the engineers

1900191019201930194019501960 This Airplanein Timewere still uncertainabout controlling theairplane at highspeeds.They weren’tsure what would happen to an airplanethat attempted to gothrough shock waves.Some believed thatthe whole airplane would vibrate andbreak apart from the pressure.Others thought there was no “soundbarrier.” As Yeager approached thespeed of sound, the airplane beganto buffet, but once Yeager passedMach 1, the airplane smoothed out.He remarked later,“Grandma couldbe sitting up there sipping lemonade.” TEST YOURSELF!THINK about the liftwings like these provide atslow speeds.Bell X-1The Bell X-1 wasmodeled after a.50 caliber bullet.Engineers usedthat shape becausebullets were known to maintainstability at supersonic speeds. Thesuccess of the X-1 proved thatairplanes could be designed forfaster-than-sound flight. It alsodispelled the notion of an actualphysical barrier at the speed ofsound. Streamlined design and arocket engine were critical factorsin reaching Mach 1.On October 14, 1947, Capt.Charles “Chuck” Yeager flew theBell X-1 at an altitude of 13,106meters (43,000 ft) at a speed ofmore than 1,120 kilometers (700miles) per hour, faster than thespeed of sound (Mach 1).Not enough! The Bell X-1 landed athigh speeds on a 4.8-kilometer(3-mile) runway. (It could take offunder its own power, but was airlaunched to save fuel.)PAGE17

RocketThrustersDual Controls—for Air and SpaceFIND the controls used inEarth’s atmosphere.The movable surfaces on the wingsthat look like ailerons are actuallyflaps, which provide additional liftas the airplane lands. What look tobe elevators on the rear horizontaltail function as both elevatorsand ailerons.They can move upand down together to controlpitch, or they can move in opposing directions to control the roll.The rudder on the vertical tailcontrols yaw.MILESTONES OF FLIGHTYou canview thisairplanefrom thislocationon thesecondfloor.XStand here to view airplanePIONEERS OF FLIGHTPAGE18RudderFlapsCombination Elevatorsand AileronsTHINK further:Whywouldn’t these controlswork in near-space?These controls work by changingthe pressure of the air that flowsover the control surfaces of theairplane.There is no air above theEarth’s atmosphere, and thereforeno air pressure to change.FIND the controls used innear-space.Find the two holes on the side ofthe airplane’s nose, the two on top,and the two on the wing. Whenyou return to the first floor andlook up at the X-15, you’ll seeanother six—two under the noseand two each on the wing. Rocketthrusters control the airplane whileit is high in the Earth’s atmosphere.Gases blast from the holes withsuch force that they push the airplane in the opposite direction.(This is the same principle by whichjet and rocket engines work).

1900191019201930194019501960 This Airplanein TimeMATCH the rocketthrusters with the three axesof control.Twelve rocket thrusters control theairplane in three axes.Two on eachside of the nose control yaw, twoeach on the top and bottom of thenose control pitch, and one eachon the top and bottom of each wingcontrol roll. Just over 50 years afterthe Wright brothers realized theneed for control in three axes, theirinsight was applied to travel in space!READ what the pilot said.When X-15 test pilot ScottCrossfield was asked how he knewwhen it was time to use one set ofcontrols rather than the other, hereplied, “When one didn’t work, Isimply used the other.” TEST YOURSELF!COMPARE the X-15with the Bell X-1. Identifythree key features on bothairplanes that reduceshock-wave drag.They have skinny noses; sleek, narrow fuselages; and short, thin wings.NorthAmerican X-15The X-15 is arocket-poweredresearch airplane. It wasbuilt to fly in bothair and space and togather information for futurespace exploration. In 1959 theX-15 became the first wingedaircraft to reach the fringes ofEarth’s atmosphere, flying to analtitude over 107 kilometers (67miles), and the first to attainspeeds of Mach 4, 5, and 6—up to7,200 kilometers (4,500 miles) perhour. That is fast enough to flyacross the United States from coastto coast in 40 minutes!Three X-15s flew 199 researchmissions. During the formativedays of Project Mercury, America’sfirst attempt to put a person inorbit, NASA engineers gave seriousconsideration to building a largerversion of the X-15 for theMercury missions. But they determined that a blunt-body reentryvehicle, such as Friendship 7,exhibited in the Milestones of Flightgallery, better deflected the heatand buffeting from shock waves.PAGE19

Flying Further FLIGHT by Don LopezA richly illustrated and fun-to-read introduction to the historyand science of flight.The perfect book for beginning aviationenthusiasts of all ages. “Bookmarks” with recommended reading lists forfamilies or preschoolers or budding curators are available inthe How Things Fly gallery Resource Center.You can alsopreview recommended books while visiting the Center. Visit the National Air and Space Museum online athttp://www.nasm.si.edu.To go directly to the How Things Flygallery: entsSpecial thanks to Bill Tinkler for his inspiring and patient instruction inaeronautics, the staff and Docents at the National Air and Space Museumfor their good ideas, and Museum visitors for their suggestions; also toDavid Gant and his colleagues in the Museum’s Exhibits Division fortheir support.CreditsAuthor Clare CuddyPhotographers Carolyn Russo (color photos on pages 6, 8, 10, 14, 18)and Mark Avino (color photos on pages 12, 16)Additional photo credits B&W photo on page 10, SmithsonianInstitution Negative 83-2946 and B&W photo on page 14,History Office, Edwards Air Force Base, CACover photo Cessna 172, courtesy of the Cessna Aircraft Company. Youcan sit in the pilot’s seat of a similar model, a Cessna 150, in the HowThings Fly gallery.Design Groff Creative, Inc.Major support for the How Things Fly gallery and the “Looking atAirplanes” visitors guide was generously provided by The BoeingCompany and the National Aeronautics and Space Administration.SmithsonianNational Air and Space MuseumEducational ServicesPublic Services DivisionExhibits and Public Services Department

wing tip. That thickly curved top and flat underside provide lift at the Spirit’s relatively slow speed of 137 to171 kilometers (86 to 107 miles) per hour.This speed and wing shape were typical of the time period. The wing is often called a “high-lift wing.” With its large fuel load, however, the Spirit needed extra lift, so the wing