ESDU A-Z Index: N-NZ

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N
see
Yawing
Yawing Moment Due To Aileron Deflection (Nξ or CnΔa)
Yawing Moment Due To Rolling (Np or Cnp)
Yawing Moment Due To Rudder Deflection (Nζ or CnΔr)
Yawing Moment Due To Sideslip (Nv or Cnβ)
Yawing Moment Due To Yawing (Nr or Cnr)
NACA 1-series Cowls
see
Cowls
NACA Aerofoils
6- and 6A-Series for Low Drag Over a Range of Lift Coefficient
comparison of geometric and inviscid flow characteristics with those of GUNACA-series, 99003
explanation of numbering system, 99003
Definition of Camber and Thickness Distributions, 97017
NACA Convergent-divergent Planform Flush Intakes
Drag
sharp or rounded nose, 86002
Pressure Recovery
sharp or rounded nose, 86002
Nacelle
see also
Aerodynamic Loading
Bodies of Revolution
Cowls
Calculation of Contribution of Rigid to Wing Deformation Using Orthogonal Modes, 97032
Calculation of Contribution to Wing Deformation Using Normal Modes, 99033
deformation of flexible assembly, 99033
Effect of Propeller Type on Sideforce and Rolling and Yawing Moments Due to Sideslip
wing mounted, 00025, TM 178
Effect of Turbine Engine Type on Rolling Moment Due to Sideslip
rear-fuselage mounted/empennage interference, 73006
underwing mounted, 00025, 73006
Effect of Turbine Engine Type on Sideforce and Yawing Moment Due to Sideslip
rear-fuselage mounted/empennage interference, 79006
underwing mounted, 00025, 79006
Effects of Rear-mounted Engine Nacelles on Sidewash at Fin, TM 184
Estimation of Aerodynamic Centre Position for Wing/Fuselage/Nacelle (Turbine Type)
effect of geometry and position for rear-fuselage mounted, 78013
effect of geometry and position for underwing mounted, 77012
program for wing-body-nacelle combinations, 13009
Estimation of Upwash Due to Turbine Engine Type, 90020
Forces acting on
Forces acting on single-stream nacelle, 16003
Forces acting on two-stream nacelle, 16003
Interference With Pusher or Tractor Propeller Flow
effect on thrust and drag, 86017
Lift and Longitudinal Forces on Combination With Wing and Flap
submerged in propeller slipstream, 88031
Naphthas
Density
typical values, 71003
Dynamic and Kinematic Viscosity
typical values, 71003
Natural Convection Heat Transfer
see
Free Convection Heat Transfer
Natural Frequency
see also
Box Structures
Buildings
Crossflow Heat Exchangers
Curved Rectangular Plates
Curved Sandwich Panels (Cores of Negligible Flexural Stiffness)
Curved Specially-orthotropic Rectangular Plates
Cylinders of Circular Section (Strength and Vibration)
Flat Panels in General
Flat Rectangular Plates
Flat Sandwich Panels (Cores of Negligible Flexural Stiffness)
Flat Specially-orthotropic Rectangular Plates
Flat Specially-orthotropic Square Plates
Flat Square Plates
Modal Density
Pipes with Internal Flow
Response of Buildings and Structures
Shell-and-tube Heat Exchangers
Definitions and Formulae, 66013, 77032
Needle Roller Bearings
see
Grease in Rolling Bearings
Rolling Bearings
Rolling Bearings for Specialised Applications
Needle Valves
Pressure Drop Across, 69022
Net Thrust
see also
Propellers
Turbo-Fan and Turbo-Jet Engines
see also
Thrust of Turbo-fan and Turbo-jet Engines
definition, 69006
effect of underwing efflux/flap interference, 82034
Neuber Equation
Plastic Stress Concentration, 76014, 95006
Neutral Atmosphere
Definition, 82026
Neutral Point
see
Longitudinal Stability and Response
Newton-cotes Formulae
Numerical Techniques for Definite Integrals
see
Quadrature
Newtonian Fluid
Definition, 68036, 91025, 95012, 97034
Newtonian Impact Theory
Applied to Calculation of Pressure Distribution on Forebody, AERO W.S.05.03.01
Newton's Laws of Motion
Application to System With Steady or Sudden Mass Change, 78038
Use in Deriving Equations of Motion in Terms of Moving Axes, 78038
Nichols Chart
Explanation With Worked Example, 74021
Use in Control System Assessment and Design
advantages and limitations, 81008
Nickel Plating
Effect on Fretting Fatigue Strength of Titanium Alloys, 88027
Nickel Steels
see also
Duplex Stainless Steels
High Alloy Steels
Composition of Specific Specifications 00932 (MMDH)
Corrosion Resistance 00932 (MMDH)
Creep Behaviour and Elongation 00932 (MMDH)
Density 00932 (MMDH)
Elastic Moduli in Compression and Tension 00932 (MMDH)
Elastic Modulus of Rigidity 00932 (MMDH)
Electrical Conductivity 00932 (MMDH)
Exfoliation Corrosion Resistance 00932 (MMDH)
Fracture Toughness
variation with temperature, 83023
Poisson's Ratio 00932 (MMDH)
Proof Stresses in Compression and Tension 00932 (MMDH)
Specific Heat Capacity 00932 (MMDH)
Stress Corrosion Resistance 00932 (MMDH)
Tensile Strength 00932 (MMDH)
Thermal Conductivity 00932 (MMDH)
Thermal Expansion Coefficient 00932 (MMDH)
Torsion and Shear Strengths 00932 (MMDH)
Weldability 00932 (MMDH)
Nitrides
see
Ceramics
Nitriding
see
Case Hardening
Wear Resistant Surface Coatings and Treatments
Nitrocarburising
see
Case Hardening
Wear Resistant Surface Coatings and Treatments
Nitrogen
Forced Convection Heat Transfer in Ducts
variable gas property effects, 81045, 92003
Gas Constant, AERO 00.01.09
Node
Pressure or Velocity
definition, 66013
Noise
see also
Acoustic Absorption Coefficient
Acoustic Impedance
Aircraft Noise Series
Control Systems
Crossflow Heat Exchangers
Noise in Air-conditioning Duct Systems
Noise Limiting Curves
Noise Prediction for Aerospace Sources
Noise/sound Propagation
Shell-and-tube Heat Exchangers
Turbo-fan and Turbo-jet Engines
Airframe noise, 90023
Boundary layer noise, 75021, TM 58
Cabin noise, internal noise, 07001
Combination of Levels, 17012, 78037
Combustor noise, combustion noise, 05001
Comparison of Levels From Various Sources, 79037
Conversion to R.M.S. Fluctuating Pressure, 66018
Definition of Pressure Correlation, 74037
Definitions of Intensity, Intensity Level, Power Level, Pressure and Pressure Level, 66013
Estimation of sideline noise in subjective noise metrics, 82027 Addendum
Fan noise, compressor noise, 98008
Fans
prediction at maximum efficiency point, 79037
Far-field jet noise, 11002, 89041, 98019
General Introduction to Concepts, Terminology and Units, 79037, 82001
Ground reflection effects, 94035
Jet-by-jet noise shielding, 88023
Lateral attenuation, 81035, 82027
Methods Used to Model Subjective Response of Human Ear, 02020
use of A-, B- or C-weighting, 79037, 82002
use of A-weighting and table of values, 02020
use of various other noise measures and their definitions, 02020
Near-field jet noise, 99006
Noise shielding by barriers, 79011
Propeller noise, 11005, 76020, 96027
Section properties of fuselage stiffeners, 07001 Addendum
Sound absorption coefficients of liners, 74003, 74004
Sound attenuation due to air absorption, 78002, 78003
Sound attenuation in circular ducts, 00012
Sound attenuation in rectangular and annular ducts, 00024
Sound Power Radiated by Dynamically Isotropic Excited Flat Rectangular or Square Plate
effect of coincidence frequency, 00002
effect of damping and stiffeners, 00002
effect of edge rotational constraint and of support angle to plate, 00002
program for modal averaged radiation efficiency, 00002
use of principle of reciprocity to determine plate response from, 00002
use of resonance frequencies to estimate edge constraint, 00002
Sound Power Radiated by One Plate of Double Wall Construction
when opposite plate is dynamically excited, 00002
Sound propagation, 94036
Sound propagation in the presence of wind and temperature gradients, 89036
Sound radiation from circular ducts, 01015
Sound Radiation From Dynamically Excited Orthotropic Flat Rectangular or Square Plate
design curves for modal averaged radiation efficiency of simply-supported, 02009
effect of coincidence frequency, 02009
program for modal averaged radiation efficiency of simply-supported, 02009
use of method for corrugated sandwich panels through equivalent orthotropy, 02009
use of method for honeycomb sandwich panels through equivalent orthotropy, 02009
use of method for ribbed (integrally stiffened) panels through equivalent orthotropy, 02009
validation of method, 02010
Static-to-flight effects, 87011
Turbine noise, 12001
Noise in Air-conditioning Duct Systems
see also
Fan Noise
Noise/sound Propagation
Attenuation in Circular- or Rectangular-Section Ducts, 81043
at 90? bends, lined or unlined, 81043
at outlets, 81043
effect of external lagging and internal lining, 81043
Attenuation in Plenum Chambers, 82002
Cylindrical Silencers With or Without Central Pod
airflow generated noise, 82002
static insertion loss, 82002
total pressure loss, 82002
Design Considerations for Acoustic Control, 82001
Duct Vibration and Rumble Noise, 81043
Flanking Transmission Prediction, 81043
Flow Generated Noise
dampers, 81043
grilles with double or single deflection, 81043
square section 90? bends with or without splitters, 81043
sudden or gradual contractions, 81043
T-junctions, 81043
General Discussion of Effect of Lining and Use of Silencers, 82002
Introduction to Acoustics for, 82001
Noise Breakout, 81043
Noise Limiting Curves to Define Sound Pressure Level Over Frequency Range
noise criterion and noise rating curves and their definitions, 82001
Rectangular Splitter Silencers
airflow generated noise, 82002
static insertion loss, 82002
total pressure loss, 82002
Room Sound Pressure Level Prediction, 81043
Typical Absorption Values for Various Room Surface Materials and Fittings, 82001
Typical Room Reverberation Times and Their Use in Prediction, 82001
Worked Example on Use of Prediction Methods, 82003
Noise Limiting Curves
Use to Define Sound Pressure Level Over Frequency Range
noise criterion and noise rating curves and their definitions, 82001
Noise Prediction for Aerospace Sources
Buzz-Saw Tones
far-field, 75020
within intake duct due to supersonic fan, 74033
Coaxial Static Subsonic Jet Far-Field
see also
Noise/sound Propagation
database, 11002
program to interpolate in or extrapolate database, 11002
Compressors in Turbo-Fan or Turbo-Jet Engines
far-field with or without inlet guide vanes, single- or multi-stage, 98008
Discrete Frequency Far- and Near-Field for Single Propeller With Axial or Non-Axial Inflow (Static/Flight)
estimation of unsteady lift coefficient for input to prediction program, 96027
program for estimation from steady or unsteady loading data, 11005
Discrete Frequency Far-Field for Single Propeller/Rotor
graphical estimation of maximum component of rotational noise, 76020
Fans in Turbo-Fan Engines
far-field with or without inlet guide vanes, single- or multi-stage, 98008
Far-Field Radiation Pattern From Open End of Unflanged Hard-Walled Cylindrical Duct
effect of external flow parallel to axis, 01015
multi-mode source assuming equal energy in each mode, 01015
multi-mode source assuming specified modes and amplitudes, 01015
multi-mode source using distribution of mono- or di-poles, 01015
single or multi-mode sources, 01015
variation forwards of aft with angle from duct axis and distance, 01015
Prediction of Airframe Noise Component-by-Component
program for aeroplanes not propeller powered, 90023
Shielding Effect of Two Identical SIngle-Stream Parallel Jets
program for estimation, 88023
Single-Stream Static Jet Near-Field, 72002, 99006
see also
Noise/sound Propagation
databases, 99006
program for interpolation in or extrapolation of database, 99006
Single-Stream Static Subsonic Jet Far-Field
database, 98019
program to interpolate in or extrapolate database, 98019
use of data to predict under flight conditions, 87011
Turbulent Boundary Layer
surface pressure fluctuations, 75021, TM 58
Noise Reduction
see
Acoustic Absorption Coefficient
Acoustic Impedance
Atmospheric Effects on Sound
Barriers
Crossflow Heat Exchangers
Lateral Noise Attenuation
Shell-and-tube Heat Exchangers
Noise Series
see
Aircraft Noise Series
Noise/sound Propagation
Correction of Measurements for Atmospheric Attenuation
broad-band noise, 78003
discrete frequency noise, 78002
Correction of Measurements for Ground Reflection, 94035, 94036
basis of theory, 94035
discussion of effect of distributed sources, 94035
effect of real filter characteristics, 94035
effect of source velocity, 94035
effect of turbulence on coherence of direct and reflected waves, 94035
ground impedance two-parameter model for use in prediction, 94035
minimisation by choice of microphone height, 94035
sensitivity of results to choice of parameters in ground impedance and turbulence models, 94035
Correction of Measurements for Temperature and/or Wind Gradients Near Ground
program, 89036
Correction of Measurements of Propagation Close to Ground
atmospheric attenuation, spherical spreading and ground reflection, 94036
Estimation of Attenuation Due to Barriers
program, 79011
Estimation of Lateral Attenuation in Subjective Units
aircraft with rear-fuselage turbo-fan or turbo-jet engines Addendum, 82027, 82027 Addendum
aircraft with underwing turbo-fan or turbo-jet engines Addendum, 82027, 82027 Addendum
Estimation of Sound Power Attenuation in Lined Annular or Rectangular Straight Ducts
ducts with liners on one wall, opposite walls or all four walls, 00024
ducts with sections having liners with different impedances, 00024
including effect of subsonic flow and boundary layer velocity profile, 00024
program, 00024
Estimation of Sound Power Attenuaton in Lined Circular Straight Ducts
ducts with sections having liners with different impedances, 00012
including effects of subsonic flow and boundary layer velocity profile, 00012
program, 00012
with various modal structures including effect of fan/stator interaction, 00012
Estimation of Third-Octave Pressures Due to Lateral Attenuation
aircraft with rear-fuselage turbo-fan or turbo-jet engines, 82027, 82027 Addendum
aircraft with underwing turbo-fan or turbo-jet engines, 82027, 82027 Addendum
Speed of Sound
use in temperature measurement, 02006
Table of One-Third Octave Frequency Bands Due to Atmospheric Attenuation
geometric centre, lower and upper frequencies, 78003
Transmission of Vibrational Power Through Lightweight Structures
see
Response of Lightweight Structures
Non-destructive Examination
Acoustic and Vibration Techniques, 91027
Advantages and Limitations of Various Methods, 91027
Applications of Various Methods, 91027
Detection Capability of Various Methods, 91027
Eddy Current Methods, 91027
Endoscopy Methods, 91027
Liquid Penetrant Methods, 91027
Magnetic Field and Particle Methods, 91027
Probabilistic Nature, 91027
Radiographic Methods, 91027
Selection of Appropriate Method, 91027
Ultrasonic Methods, 91027
Use of for In-Service Inspection or During Manufacture, 91027
Use of Stress Jacking, 91027
Visual Examination Methods, 91027
Non-linear Systems
Use of Describing Functions
for closed-loop response to sinusoidal input, 84032
for stability determination and prediction of limit cycles, 84009
to represent backlash, deadzone, ideal relay, hysteresis or saturation, 84009
Non-newtonian Fluids
see also
Pressure Drop in Non-newtonian Flow
Transition
Characterisation by Viscometric Measurements
see
Viscometers
Classification by Flow Curve Under Steady Shear
Bingham plastic, 95012, 97034
shear-thickening or dilatant, 95012, 97034
shear-thinning or pseudoplastic, 95012, 97034
viscoplastic or yield-pseudoplastic, 95012, 97034
Classification by Phase Condition as Homogeneous or Pseudohomogeneous, 95012, 97034
determination of whether settling or non-settling for pipeline design, 95012
Classification by Rheological Type
time-dependent behaviour of thixotropic or viscoelastic, 95012, 97034
Constitutive Equations to Model Flow Curves
Bingham plastic, 91025, 95012, 97034
Casson, 97034
Cross, 97034
Herschel-Bulkley, 91025, 97034
Metzner-Reed generalised method, 91025
power law, 91025, 97034
Typical Flow Behaviour of Real Under Range of Shear Rates, 97034
Typical Range of Shear Rates in Various Flow Processes, 97034
Typical Variation of Viscosity With Shear Rate
effect of concentration, molecular weight and temperature for polymeric, 97034
effect of concentration on particulate, 97034
Normal Distribution
see
Statistics
Normal Force
see also
Boundary Walls and Fences
Hoardings (Elevated Above Ground Level)
Lift
Lift Force Due To Pitching (ZQ or Czq)
Lift Variation with Control Deflection
Pressure Distribution
Profile Drag
Sideforce
Bodies of General Cross Section
elliptical, 05015
square with corner rounding, 07005
square without corner rounding, 04007
triangular without corner rounding, 04007
Controls, AERO F.05.01.01
Flaps, AERO F.05.01.01
Flat Plates Inclined to Flow
circular, 70015
elliptical, 70015
rectangular, 70015
semi-elliptical, 70015
square, 70015
triangular, 70015
Flat Plates Normal to Flow
annular, 70015
circular, 70015
effect of turbulence, 70015
elliptical, 70015
interference effects between parallel pair, 70015
perforated, 70015
rectangular, 70015
semi-elliptical, 70015
shear flow effects on rectangular, 70015
square, 70015
triangular, 70015
Forebody-Cylinders With Boat-Tailing
incidences to 90? and Mach numbers to 5, 87033, 89014, 90034
Forebody-Cylinders Without Boat-Tailing
incidences to 90? and Mach numbers to 5, 89014, 90034
Grid Constructed of Flat Strips Normal to Flow, 70015
In Plane of Single or Contra-Rotating Propellers at Low Forward Speeds
due to local angle of attack, 89047
Sharp-Edged Delta, Cropped Delta and Rectangular Wings of Low Aspect Ratio
in combination with axisymmetric body in supersonic flow to high angles of attack, 91042
isolated in subsonic flow to high angles of attack below stall, 93034
isolated in supersonic flow to high angles of attack, 90013
Sharp-Edged Low Aspect Ratio Wings Mid-Set on Axisymmetric Body
cruciform or monoplane, angle of attack to 60? in supersonic flow, 91042
Slender Wings
increment due to ground effect, 71007
non-linear effects in free air, 71006
Spherically-Blunted Cone and Tangent Ogive Forebodies Due to Pressure Only
at low angles of attack and transonic speeds, 89033
Two-Dimensional Circular-Section Cylinders Inclined to Flow, 80025
distributed roughness effects, 80025
turbulence effects, 80025
Two-Dimensional Stranded Cables Inclined to Flow, 80025
Normal-force-curve Slope
see also
Lift-curve Slope
Forebody-Cylinders With Boat-Tailing
zero incidence and Mach numbers to 5, 87033, 89008
Forebody-Cylinders Without Boat-Tailing
zero incidence and Mach numbers to 5, 89008
Isolated Wings, 93034
Slender Wings, 71006
Normal Freezing/melting Point
see
Melting Point
Normal Mode Analysis
see also
Response of Buildings and Structures
Response of Structures
equation for calculating response of buildings to wind loads, 77032, 83009, 91001
introduction to use in calculation, 77032, 97033
use in calculating response of cylinders to vortex shedding, 96030
use in calculating response to turbulence, 87035, 88019, 89049
Use in Calculating Deformation of Flexible Aircraft, 99033
Normal Shock Waves
see
Shock Waves
Nose and Horn Balance
see
Hinge Moment
Notation
Aircraft Dynamics, 67001, 67002, 67003, 67036, 67037, 67038, 86021
comparison of US and UK (ISO), 86021
Aircraft Fatigue Analysis, 70016
Notches
Effect on Fatigue Strength
see also
Aluminium Alloys
Austenitic Stainless Steels
Fatigue Under Variable Amplitude Loading
High Tensile Low Alloy Steels
Maraging Steels
Precipitation Hardening Stainless Steels
Stress Concentration
Titanium Alloy (Ti-4Al-4Mo-2Sn-0.5Si)
Titanium Alloy (Ti-5Al-2.5Sn)
Titanium Alloy (Ti-6Al-4V)
Titanium Alloy (Ti-6Al-6V-2Sn)
effect of mean stress, FAT A.00.02
effect of scale, 87016
Fatigue Strength Reduction Factors, 75022
Stress Concentration Data
see
Notches in Flat Plate
Notches with Flat Bottoms in Bars or Strips
Notches with Flat Bottoms in Edge of Plate
U-notches in Bars or Strips
U-notches in Edge of Plate
Wings
see
Wing Cranks or Notches
Notches in Flat Plate
Stress Concentration Due to Tensile Loading
stress concentration factors for fillets and optimised shape fillets in large plates, 15006
Notches with Flat Bottoms in Bars or Strips
Axial Load or Bending
stress concentration data, 09014
Notches with Flat Bottoms in Edge of Plate
Axial Load
stress concentration data, 79008
Nozzles
see also
Turbo-fan and Turbo-jet Engines
Compressible Flow Equations and Curves
see
One-dimensional Flow
Convergent Nozzle in Altitude Test Facility, TM 189
Use of Liners to Attenuate Noise Transmission
see
Acoustic Absorption Coefficient
Acoustic Impedance
Vectored-Jet-Thrust Aircraft
see
Vectored-jet-thrust Aircraft
Nozzle-type Flowmeters
Pressure Drop Across, 66030
Nr Curves
Noise Rating
Numerical Analysis
see
Curve Fitting
Differential Equations
Optimisation
Quadrature
Regression
Nussdorfer Criterion
Rectangular External-Compression Double-Ramp Intakes
limiting Mach number on second ramp, 75005
Nusselt Number
see
Forced Convection Heat Transfer
Nuts
see also
Double Lock Nuts
Steel
fatigue strength under axial load, 84037
Nyquist Diagram
see also
Inverse Nyquist Diagram
Approximation by Circle-Fit to Frequency Response Measurements
determination of undamped natural frequency and damping of modes, 90006, 93016
Explanation With Worked Example, 74021
Use in Control System Assessment and Design
advantages and limitations, 81008
examples in practical situations, 81040
flowchart, 81008
Use to Estimate Characteristic Equation Roots, 74021

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