Aerodynamics for Naval Aviators PDF
Preview Aerodynamics for Naval Aviators
AERODYNAMICS FOR NAVAL AVIATORS CMAL'S PIIOTMOP CjoholA P'Ici Shop AERODYNAMICS FOR NAVAL AVIATORS BY H. H. Hurt, Jr. University of Southern California ISSUED BY THE OFFICE OF THE CHIEF OF NAVAL OPERATIONS AVIATION TRAINING DIVISION U.S. NAVY, 1960 NAVWEPS 00-80T-80 REVISED JANUARY 1965 PREFACE The purpose of this textbook is to present the elements of applied aerodynamics and aeronautical engineering which relate directly to theproblemsofflyingoperations AllNavalAviatorspossessanatural . interest in the basic aerodynamic factors which affect the performance of all aircraft. Due,to the increasing complexity of modern aircraft, this natural interest must be applied to developa sound understanding ofbasic engineeringprinciples and an appreciation ofsomeofthemore advanced problems of aerodynamics and engineering. The safety and effectiveness of flying operations will depend greatly on the under- standing and appreciation of how and why an airplane flies. The principles ofaerodynamicswillprovidethefoundationsfordeveloping exacting and preciseflying techniques and operational procedures. The content of this textbook has been arranged to provide as com- plete as possible a reference for all phases offlying in Naval Aviation. Hence, the text material is applicable to the problems of flight train- ing, transition training, and general flying operations. The manner ofpresentation throughout the text has been designed to provide the elements ofboth theory and application and will alloweitherdirected or unassisted study. As a result, the text material will be applicable to supplement formal class lectures and briefings and provide reading material as a background for training and flying operations. Much of the specialized mathematical detail of aerodynamics has been omitted wherever it was considered unnecessary in the field of flying operations. Also, many of the basic assumptions and limita- tions ofcertain parts ofaerodynamic theoryhave been omittedfor the sakeofsimplicityandclarityofpresentation. Inordertocontendwith these specific shortcomings, the Naval Aviator should rely on the assistance ofcertain speciallyqualified individualswithin Naval Avia- tion. For example, graduate aeronautical engineers, graduates of the Test Pilot Training School at the Naval Air Test Center, graduates of theNavalAviationSafetyOfficersCourse, andtechnicalrepresentatives ofthemanufacturersarequalified toassist in interpretingandapplying the more difficult parts ofaerodynamics and aeronautical engineering. To be sure, the specialized qualifications of these individuals should be utilized wherever possible. NAVWEPS 00-80T-80 PREFACE The majority of aircraft accidents are due to some type of error of thepilot. Thisfact has been truein thepast and, unfortunately, most probablywill betrue in thefuture. Each Naval Aviator should strive to arm himself with knowledge, training, and exacting, professional attitudes and techniques. The fundamentals of aerodynamics as pre- sented in this text will provide the knowledge and background for safe and effective flying operations. The flight handbooks for the air- craft will provide the particular techniques, procedures, and operating datawhicharenecessaryforeachaircraft. Diligentstudyandcontinu- ous training are necessary to develop the professional skills and tech- niques for successful flying operations. The author takes this opportunity to express appreciation to those whohaveassisted in thepreparation ofthemanuscript. Inparticular, thanks are due to Mr. E. Fairchild for his assistance with the por- J. tions dealingwith helicopteraerodynamics and roll couplingphenom- ena. Also, thanks are due toMr.J. F. Detwiler and Mr. E. Dimitruk for their review of the text material. Hugh Harrison Hurt, Jr. August 1959 University ofSouthern California Los Angeles, Calif. NAVWEPS 0O-80T-80 TABLE OF CONTENTS TABLE OF CONTENTS Page PREFACE iii CHAPTER BASIC AERODYNAMICS I: WING AND AIRFOIL FORCES PROPERTIES OF THE ATMOSPHERE i Staticpressure Temperature Density Viscosity Standardatmosphere Pressurealtitude Densityaltitude BERNOULLI'S PRINCIPLE AND SUBSONIC AIRFLOW 4 Bernoulli'sequation 6 Incompressible flow Variation ofstatic pressureandvelocity Kinetic andpotentialenergyofflow Static anddynamicpressure, q Factors aff"cctingdynamicpressure Airspeedmeasurement 9 Stagnationpressure Measurementofdynamicpressure Pitotandstaticsources Indicated airspeed Calibrated airspeed Equivalentairpseed Trueairspeed DEVELOPMENT OF AERODYNAMIC FORCES 14 Streamlinepatternandpressuredistribution 14 Generationoflift 16 Circulation Pressuredistribution Airfoilterminology 20 Aerodynamicforce coefficient 22 Basicliftequation 23 Liftcoefficient Dynamic pressureandsurfacearea V NAVWEPS 00-80T-80 TABLE OF CONTENTS Pase Interpretationoftheliftequation 23 Liftcoefficientversus angleofattack Stall speed and angleofattack Angleofattackversusvelocity Primarycontrolofairspeed Airfoilliftcharaaeristics 27 Sectionangle ofattackand liftcoefficient Typical sectioncharacteristics Effectofthickness andcamber Drag characteristics 29 Dragequation Dragcoefficientversus angle ofattack Lift-dragratio Power-offglideperformance Airfoildragcharacteristics 33 Sectiondragcoefficient Typical sectioncharacteristics Effectofthickness andcamber Lowdragsections FLIGHT AT HIGH LIFT CONDITIONS 35 Stallspeeds 35 Maximumliftcoefficient Stall angleofattack Effeaofweight 35 Effectofmaneuveringflight 35 Loadfactorversusbank angle Stall speed versusloadfactor Effect of high liftdevices 37 Effectonstall speed Stallangleofattackandstallrecovery 39 HIGH LIFT DEVICES 39 Types of high lift devices 41 Plainflap Splitflap Slottedflap Fowlerflap Slots and slats Boundary layercontrol Operationofhighliftdevices 43 Flapretractionandextension Changes in lift, drag, and trim Effectofpower DEVELOPMENTOFAERODYNAMICPITCHINGMOMENTS Pressuredistribution 47 Centerofpressureandaerodynamiccenter 47 Pitchingmoment coefficient 49 Effectofcamber Effectofflaps Relationship between center of pressure, aerodynamic center, and moment coefficient Applicationtolongitudinalstability 51 Stabilityand trim Effectofsupersonic flow vi NAVWEPS 0O-80T-8O TABLE OF CONTENTS Pat* FRICTION EFFECTS '2 Viscousflow '^ Boundarylayers '^ Laminar flow Transition Turbulentflow ReynoldsNumber '^ Definition SkinfrictionversusReynoldsNumber Airflowseparation '° Pressure distribution Pressuregradientandboundarylayerenergy Factorsaffectingseparation Scaleeffect. '^ Effecton aerodynamiccharacteristics ReynoldsNumbercorrelation PLANFORM EFFECTS AND AIRPLANE DRAG EFFECT OF WING PLANFORM 61 Descriptionofplanform °^ Area, span, andchord Aspect ratioand taper Sweepbaclc Mean aerodynamicchord Developmentofliftbyawing 63 Vortex system Tipandboundvortices Induced flow and downwash Section angleofattack Induced angle ofattack INDUCED DRAG ^^ Inducedangleofattackandinclinedlift 66 6° Induceddragcoefficient Effect ofliftcoefficient Effectofaspectratio Effeaoflift JJ Effeaofaltitude °^ Effeaofspeed Effectofaspearatio 71 Lift and dragcharacteristics Influence oflowaspectratioconfigurations EFFECT OF TAPER AND SWEEPBACK 74 74 Spanwiselift distribution LEfofceacltoinndluicftedanfdlodwragcharacteristics ''J°^ STALL PATTERNS '''' Favorable stallpattern '' Effeaofplanform Taper Sweepback ^6 Modificationsforstallcharaaeristics vii NAVWEPS 0O-80T-80 TABLE OF CONTENTS Page PARASITE DRAG 87 Sourcesofparasitedrag 87 Parasitedragcoefficient 87 Parasiteandinduceddrag 89 Minimumparasitedragcoefficient Airplaneefficiencyfactor Equivalentparasitearea Eflfectofconfiguration 91 Effeaofaltitude 91 Eflfectofspeed 91 AIRPLANE TOTAL DRAG 92 Drag variationwith speed Induced and parasitedrag Stall speed Minimumdrag Specific performance conditions Compressibilitydragrise CHAPTER AIRPLANE PERFORMANCE 2. REQUIRED THRUST AND POWER DEFINITIONS 96 Parasiteandinduceddrag 96 Thrustandpowerrequired 97 VARIATION OF THRUST AND POWER REQUIRED Eflfectofgrossweight 99 Eflfectofconfiguration 101 Eflfectofaltitude 101 AVAILABLE THRUST AND POWER PRINCIPLES OF PROPULSION 104 Massflow, velocitychange, momentumchange 104 Newton'slaws 104 Wastedpower 104 Poweravailable 106 Propulsionefficiency 106 TURBOJET ENGINES Operatingcycle 107 Functionofthecomponents 109 InletordifFuser Compressor Combustionchamber Turbine Exhaustnozzle Turbojetoperatingcharaaeristics 116 Thrustand poweravailable Effectofvelocity Effectofenginespeed Specificfuelconsumption Effectofaltitude Governingapparatus Steadystate, acceleration, deceleration Instrumentation viii
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