Aerodynamics for Naval Aviators

436 Pages·1965·54.972 MB·English

by  Hugh Harrison Hurt

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
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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