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CHAPTER1IntroductiontoAeronauticsWhatisAeronautics?AeronauticsVersusAerospaceBeforetherecanbeadiscussionaboutaeronautics,itmustbedefinedabitbetter.Aeronauticsisthescienceofdesigninganairplaneorotherflyingmachine,Therearefourbasicsubjectsthataeronauticalengineersmustunderstand.Aeronautic航空Aerospace航天Versus比较，对抗Tail尾翼Aerodynamic空气动力学Spin旋转Propeller螺旋桨Fallapart分离，分解，崩溃Aircraftcarrier航空母舰•1.Howtoshapetheairplaneanditswingandtailsothatitslipseasilythroughtheairandcanliftitselfofftheground.Thisiscalledaerodynamics.•2.Howtocontroltheairplanesothatitwillbeabletoturnbutnotspinoutofcontrol.Thisiscalledstabilityandcontrol.•3.Howtobuildanengine(beitjetorpropeller)sothattheairplanecanpushitswaythroughtheair.Thisiscalledpropulsion.•Howtobuildtheairplanesothatitwon’tfallapartwhenithitsagustofwindorslamsdownonanaircraftcarrier.Thisiscalledstructures.•Aeronauticalengineeringshouldnotbeconfusedwithaerospaceengineering,whichdealswiththingssuchasrocketsandsatellites.Whilerocketsmustascendthroughtheatmosphere,theymustalsonavigatethroughspacewherethereisnoair.Theirdesignsandengineshaveverydifferentrequirementsthanthoseofairplanes.HowAirMoves-AerodynamicsHowAirandotherGasesMove-Aerodynamics•Aerodynamicsisthestudyofforces(morepushesandpulls)actingonanobjectbecauseairoranothergasismovingaroundit.Theseforcesareimportantforthedesignofairplanes,sailboats,cars,andotherobjectsmovingquicklythroughtheair.Buildings,bridges,andwindmillsarealsoaffectedbythewindmovingpastthem,andtheyalsoexperienceaerodynamicforces.•Thebulkofthesectionsinthischapteraredevotedtounderstandingthemotionsofairaroundobjects.Whenthesemotionsaredefinedandmeasured,theycontributetothecalculationoftheforcesontheobject.Withtheaerodynamicforcesknown,theflightpossibilitiesoftheobjectcanbediscussed!Measurements•Inordertodetermineiftheaerodynamicforcesonanobjectaresufficienttoallowflight,theforcesmustbemeasured.Thedifferentcontributionsoftheairmovingaroundtheobjectmustbecategorizedanddefined,andtheymustbequantified.Therearespecificqualitiesthatareusedtocategorizeanddefinethesecontributions.Inaddition,thesequalitiesneedaguidelinetomeasurethemby.Theguidelinesarecalledunits,andthequalitiesaremass,time,length,andtemperature.Unit•Unitsareusedtodefinemeasurementssothateveryoneknowsexactlyhowmuch.Theysoundverytechnical,buttheyareusedallovertheworldineverydayexamples.Itisimportanttoalwaysincludetheunitswhentalkingaboutmeasuringaquality.Ifabridgedesignerdevelopsabridgeacrossariverthatissupposedtobe1000meterslong(ameasureoflength),andoneofthebuilderstellshimorherthatthebridgeisshortby1,whatdoesthatmean?Ifitis1centimetershort(1/100ofameter),itwon’tbeaproblem–itcan’tevenbeseen.Ifitis1metershort,itmaycauseaproblemyearslateriftheriverbankerodesaway.Ifitisshortby1%(10meters),thebridgemaynotreachtheothersideoftheriver!Sounitsareveryimportant!Ameasurementshouldalwaysinclude2things:anumberandaunit.Someexampleseveryonemayknowincludethingslike:thereare20minutesuntilrecess;ittakes10daystodriveacrossthecountry:adesktopis20incheswideand25incheslong;arecipeuses2cupsofflour;itis85degreesoutsidetoday.Eachofthesemeasurementsincludesanumberandaunit.Recess休息，休会，切口，凹口，凹槽，退刀槽，环槽Recipe处方，配方，诀窍，秘诀Mass•Everything,whetheritisasolid,liquid,orgashasmass.Itisameasureofhowmuchofthesubstanceisinvolved-howmanymolecules.Massissometimesusedinterchangeablywithweight(moreonthatinthepropertiessection),eventhoughtheyarenotthesame.Inthemetricsystem,theunitsformassaregrams,kilograms(1000grams)ormilligrams(1/1000grams).IntheAmericanunits(calledtheEnglishsystem),theweightofthesubstanceisused,inpoundsorounces.Apoundis16ounces.Often,abbreviationsareusedfortheunits:agramisg.akilogramiskg,amilligramismg,apoundislb,andanounceisoz.•substance物质，物体，实体•molecules分子•interchangeably交替的，可拆卸的，可交换的•metric度规，度量标准，量度•ounce盎司（1盎司＝28.349克）•abbreviation缩短，缩写Time•Theeasiestwaytothinkoftimeishowlongittakessomethingtohappen.Itmaytake10minutestodrivetoschool;itmaytakeanhourtoeatdinner.Theunitsfortimearethesamearoundtheworld:seconds,hours,days,years.Inaerodynamics,acommontimemeasurementishowlongittakesanobjecttogofromonepointtoanother,orfrompointAtopointB.Length•Howlongisit?Howfarisit?Thesearequestionsheardeveryday.Lengthisaqualityusedbymanypeopletodefineanobject.Apencilis7incheslong.Astudentis4feettall.Aswimmingpoolis2metersdeep.Themostcommonunitsforthemetricsystemareacentimeter,ameter(100centimeters),andakilometer(1000meters).IntheEnglishsystemthatmostAmericansuse,commonunitsaretheinch,afoot(12inches),oramile(5280feet).Theseunitsmaybeabbreviated:centimeterascm,meterasm,kilometeraskm,inchasin,footorfeetasft,andamileasmi.•quality性质，性能，属性•multiply复合地，多样地，并联，复杂，增殖•acre英亩•mile英里•dimension尺寸，线度，量纲•cabin座舱•cube立方，立方体•inch英寸•cubic立方体的，三次的•gallon加仑•Inadditiontothelengthofanobject,itoftenusefultoknowtheareaorvolumeoftheobjectinquestion.Theareaishowmuchroomisonasurfaceliketheflooroftheclassroomorthesurfaceofawing.Itisfoundbymultiplyingonelengthbyanother(onesideoftheroombythefrontforexample),andtheunitsarelengthsquared.Socommonmeasurementsforareainscienceanden