ESDU A-Z Index: L-LIF

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

| L-LIF | lig-lz |

see: Rolling Moment; Rolling Moment Due To Rolling (L_p or C_lp); Rolling Moment Due To Rudder Deflection (L_ζ or C_{l Δ r}); Rolling Moment Due To Sideslip (L_v or C_{l β}); Rolling Moment Due To Yawing (L_r or C_lr)

Labyrinth Seals

see also: Rotating Machinery

see: Rotary Seals

Design of, 09004
Performance Assessment of, 09004
Selection of, 09004, 80012
Types Available: advantages and limitations, 09004, 80012; life, 09004, 80012; maximum fluid pressure and shaft speed, 09004, 80012; radial, 09004; shaft and housing finishes required, 09004, 80012; special design features that can be used, 09004, 80012; staggered, 09004; stepped, 09004; straight-through, 09004; typical applications, 09004, 80012

Lag

Air Temperature Probes: response to transients, 84007
Anemometric Data Measuring System in Aircraft: effect of transition from laminar flow on use of ground calibration, 87038; experimental determination for installed system, 87038; incorporation of correction to pitot and static pressures, 83029, 87038, 88025; pitot and static errors due to, 85011; theoretical treatment of acoustic and viscous, 87038
Calibration of Pressure Air Data Systems, 20006

Laminar Flow

see: Aerodynamic Heating; Boundary Layer; Falling Film Evaporation; Forced Convection Heat Transfer; Free Convection Heat Transfer; Journal Bearings; Mixed Forced-Free Convection Heat Transfer; Pressure Drop in Internal Flow; Pressure Drop in Non-Newtonian Flow

Laminated Construction Using Composites

see also: Beams of Sandwich Construction; Corner Section in Specially-Orthotropic Plates; Curved Sandwich Panels (Cores of Negligible Flexural Stiffness); Curved Specially-Orthotropic Rectangular Plates; Curved Unbalanced Laminated Rectangular Plates; Cylinders of Laminated Construction; Faceplate Wrinkling; Failure Modes; Flat Panels with Fibre-Reinforced Unflanged Integral Stiffeners; Flat Sandwich Panels (Cores of Negligible Flexural Stiffness); Flat Sandwich Panels (Corrugated Cores); Flat Sandwich Panels (Truss Cores); Flat Specially-Orthotropic Rectangular Plates; Flat Specially-Orthotropic Square Plates; Flat Strips of Orthotropic Materials; Flat Unbalanced Laminated Rectangular Plates; Sandwich Panels and Plates; Spherical Shells of Laminated Construction; Struts of Sandwich Construction

Criterion for Edge Delamination Failure, 95028

Definition of Balanced and Unbalanced Laminates, 94003

types of stiffness coupling in unbalanced, 94003

Dynamic Response to Excitation

see: Response of Lightweight Structures

Elastic Constants

calculation from properties of individual layers, 02009, 83035, 94003

calculation from properties of matrix and fibres, 02009, 83035

Fatigue Strength Under Acoustic Loading

aluminium-glassfibre epoxy (GLARE) laminates including temperature effects, 84027

design considerations to improve, 86025

fibre-reinforced laminates and skin-rib joints, 84027

Flexural and In-Plane Stiffnesses

calculation from properties of individual layers, 02009, 83035, 94003

calculation from properties of matrix and fibres, 02009, 83035

related to any reference plane in terms of those related to central plane, 94003

Interlaminar Stresses at Free Edges in Composite Plates Under Uniaxial Strain

program for estimation, 95028

use to predict delamination, 95028

Layer Strains and Stresses

formulae for transforming values between axes systems, 94003

Layer Stresses in Balanced and Unbalanced Laminates

due to applied loads and moments and temperature variation, 94004

due to method of manufacture, 94004

Layer Stresses in Unbalanced Laminates

due to restraining flat, 94004

Plate Curvatures and Strains for Balanced and Unbalanced Laminates

due to applied loads and moments and temperature variation, 94004

due to method of manufacture, 94004

Plates Tapered in Thickness by Ply Drop-Offs

program to predict uniaxial load for delamination, 91003

use of fracture mechanics to predict delamination, 91003

Plate Strains for Unbalanced Laminates

due to restraining flat, 94004

Program to Compute Stress and Strain Distribution Around Circular Hole, 85001

use to design reinforcement in fibre-reinforced composites, 86003

Program to Design Most Effective Laminate to Support In-Plane Loads and Bending Moment

choice of ply thicknesses and lay-up using 0?, 90?, ?45? layers only, 96036

Stacking Sequences for Special Orthotropy, 82013

selection of stacking sequence to meet stiffness criteria, 82013

Structural Damping

discussion of effect of fibre angle, length and volume, and temperature, 91012

program for calculation of fibre-reinforced, 85012

typical values, 91012

Through-Thickness Shear Stiffnesses of Plate Materials, 89013

illustration of trends with material characteristics, 89013

Lanchester Balancer

Partial Balancing of Planar Multi-Bar Linkages: design of generalised to eliminate single frequency of frame shaking force/moment, 90007; design to eliminate single frequency of frame shaking force, 90007

Landing

Autolanding Threshold Dispersion Data Analysis

as illustration of use of statistical techniques, 91019

Correlation of Changes in Drag-Minus-Thrust and Lift in Airborne Manoeuvre

deduced from speeds at screen and touch-down, 91032, 92020

discussion of effect of landing style, 92020

example plots for wide range of aircraft and power plants, 92020

Determination of Airborne Distance By Regression Applied to Measurements

of airborne time, and screen and touch-down speeds and rates of descent, 92022

Development of Relation Between Approach Speed and Ground Run

by regression applied to measurements, 92021

Estimation

see also: Accumulation of Rainfall; Aircraft Tyres; Brakes; Braking; Friction Coefficient; Ground Effect in Fluid Flow; Ground Performance in Take-Off and Landing; Planing of Aircraft Tyres; Runways

airborne distance, 91032, 92020

approach speed, PERF EG6/2

average value of drag-minus-thrust during airborne phase, 91032

certification airborne manoeuvre, 91032

circular arc representation of airborne phase, 91032

discussion of deceleration techniques, 85029

effect of power cut height on airborne distance, 91032

effect of runway gradient, 91032

effect of wind and wind gradient on airborne distance, 91032, 92020

field length factors defined by airworthiness requirements, 84040

ground run, PERF EG6/4

ground run prediction on wet runway from aircraft stopping distance test data, 99015

ground run prediction on wet runway from friction ground-test machine data, 99015

introduction to Data Items on, 80026

limiting speeds defined by airworthiness requirements, 85029

speed loss in airborne phase to touch-down, 91032

thrust decay of turbo-fan and turbo-jet engines, 85029

time delays in response of mechanical deceleration devices, 85029

time from screen to touch-down, 91032

total distance from 50 ft, 84040

touch-down speed from airborne time and screen speed, 92020

typical speed losses before brake application, 85029

typical touch-down speeds related to screen speeds, 85029

typical values of deceleration in ground run, 76011

use of braking parachutes, 85029

Fatigue Loading in Ground Run

see: Fatigue Loading

Impingement Drag Due to Tyre Sidespray Impacting Airframe

see: Impingement Drag

Prediction of Tyre Sidespray Envelope for Water and Slush, 83042

Reduction of Measured Data, 80009, PERF RG2/1

vectored-jet-thrust aircraft, 87037

Turbulence During Approach

see also: Turbulence Near Ground

stalling due to, PERF EG6/2

Landing Gear

see: Undercarriage; Undercarriage Drag Estimation

Lap Joints

Fatigue Strength

see: Bolted Double Lap Joints in Steels; Bonded Single-Lap Joints in Clad Aluminium Alloys; Fretting Fatigue; High-Load Transfer Joints in Aluminium Alloys; Low-Load Transfer Joints in Aluminium Alloys; Medium-Load Transfer Joints in Aluminium Alloys; Riveted Lap Joints in Aluminium Alloy Sheets

Strength Analysis

see also: Bolted Lap Joints; Bonded Double- or Single-Lap Joints; Bonded Double-Lap Joints; Bonded Joints; Bonded Single-Lap Joints

maximum stresses in plates under compression or tension, 67008

Laplace Transform

Relationship With Z-Transform, 86037
Table of Useful Forms, 69025
Use in Solution of Differential Equations With Worked Examples, 69025

Laser Transformation

Surface Treatments of Steels to Improve Fatigue Strength: advantages and limitations, 89031; comparison with other possible surface treatments, 89031

Latent Heat of Vaporisation

See under compound of interest

Lateral Noise Attenuation

see also: Atmospheric Effects on Sound

Estimation for Aircraft With Rear-Fuselage Turbo-Fan or Turbo-Jet Engines: effect of distance and elevation angle on third-octave sound pressures, 82027, 82027 Addendum; in subjective noise units Addendum, 82027, 82027 Addendum; program for third-octave sound pressures
Estimation for Aircraft With Underwing Turbo-Fan or Turbo-Jet Engines: effect of distance and elevation angle on third-octave sound pressures, 82027, 82027 Addendum; in subjective noise units Addendum, 82027, 82027 Addendum; program for third-octave sound pressures
Explanation of Derivation of Prediction Method for Aircraft: effect of aircraft flow field, 81035; effect of jet-by-jet shielding, 81035, 88023; effect of meteorological conditions, 81035; effect of sampling time, 81035; elimination of background noise, 81035; use of ground reflection correction to data, 81035; use of measured or predicted atmospheric attenuation, 81035

Lateral Stability and Response

see also: Asymmetric Flight; Derivatives; Dynamic Stability

Approximate Solution to Modes of Motion, 83024: comparison with full solution for particular aircraft, 83024
Description of Modes of Lateral Motion and Effect of Aircraft Characteristics on Them: Dutch roll, 83024, 86021; rolling subsidence and spiral mode, 86021
Desirable Characteristics of Lateral Modes for Good Aircraft Handling Qualities, 92006
Effect of Control Augmentation on Dutch Roll, 83024
Effect of Idealised Yaw Damper on Dutch Roll, 83024
Equations of Motion: rigid aircraft, 67003, 83024, 86021; separation of lateral/longitudinal sets and appropriate characteristic equations, 67003, 86021
Estimation of Roll Response to Aileron Input, PERF EG8/2
Inertia Coupling of Lateral/Longitudinal Equations: rapid rolling manoeuvre, 67005, 67006, 67007
Requirements for Minimum Values of Damping and Frequency of Dutch Roll: for military aircraft handling, according to aircraft class and flight phase, 92006
Requirements for Roll Performance and Roll Time Constant: for military aircraft handling, according to aircraft class and flight phase, 92006

Lattice Structures of Flat-Sided And/or Tubular Members

Dynamic Response to Turbulence and Wind

see: Response of Buildings and Structures; Response of Buildings and Structures To Atmospheric Turbulence

Mean Forces and Moments Due to Wind or Other Fluid Flows

see: Overturning Moment on Surface-Mounted Structures; Profile Drag; Sideforce; Torsional Moment on Structures

Mechanical Vibration Characteristics

see: Buildings

Layered Structure

see: Laminated Construction Using Composites

Lead/bismuth Eutectic Solution

Dynamic and Kinematic Viscosity: temperature variation in liquid state, 66024

Leading-Edge Devices (sealed)

see also: Leading-Edge High-Lift Devices

Choice of Optimum Deflection on Aerofoil Using Multivariate Gradient Search and CFD Codes: example studies for single design point, 00022, 00023, 99020; example study together with camber line shape for two design points, 99021; example study together with surface shape for two design points, 01024
Effect of Deflection on Drag, Lift, Hinge and Pitching Moments and Pressure Distribution: in subsonic or transonic flow, 01033
Effect of Deflection on Drag, Lift, Pitching Moment and Pressure Distribution: in subsonic or transonic flow, 96028, 96029

Leading-Edge High-Lift Devices

Drooped Leading Edge or Plain Flap: angle of attack for maximum lift of aerofoils and wings, 96003; effect on lift of wings at zero angle of attack, 96032, 97002; effect on maximum lift of basic aerofoil and its lift at zero angle of attack, 94027; effect on maximum lift of wings, 92031; effect on pitching moment of basic aerofoil and wing, 00029, 03017; lift curve from zero to maximum lift of aerofoils and wings, 96003; program to predict, 99031
Effect of Deflection on Drag, Hinge and Pitching Moments, Lift and Pressure Distribution: in subsonic or transonic flow, 01033
Example of Calculation of Local Excrescence Contribution to Drag, 93032
Slats or Sealed Slats: angle of attack for maximum lift of aerofoils and wings, 96003; effect on lift of wings at zero angle of attack, 96032, 97002; effect on maximum lift of basic aerofoil and its lift at zero angle of attack, 94027; effect on maximum lift of wings, 92031; effect on pitching moment of basic aerofoil and wing, 00029, 03017; lift curve from zero to maximum lift of aerofoils and wings, 96003; program to predict, 99031
Slats or Sealed Slats in Combination With Trailing-Edge High-Lift Devices: angle of attack for maximum lift of aerofoils and wings, 96003; effect on lift of wings at zero angle of attack, 93019, 95021, 96032, 97002, 97009, 97011; effect on maximum lift of basic aerofoil and its lift at zero angle of attack, 94027, 94028, 94029, 94030, 94031; effect on maximum lift of wings, 91014, 92031; effect on pitching moment of basic aerofoil and wing, 00029, 03017; lift curve from zero to maximum lift of aerofoils and wings, 96003; program to predict, 99031
Unvented and Vented Krugers: angle of attack for maximum lift of aerofoils and wings, 96003; effect on lift of wings at zero angle of attack, 96032, 97002; effect on maximum lift of basic aerofoil and its lift at zero angle of attack, 94027; effect on maximum lift of wings, 92031; effect on pitching moment of basic aerofoil and wing, 00029, 03017; lift curve from zero to maximum lift of aerofoils and wings, 96003; program to predict, 99031
With Slot: contribution to airframe noise, 90023

Leading-Edge Suction

Aerofoils: attainable value from theoretical value for thin aerofoil, 95025, 96025
Swept Non-Planar and Planar Wings to High Angles of Attack at Subsonic Speeds: spanwise distribution of attainable values, 96025
Swept Straight-Tapered Plane Wings at Supersonic Speeds, AERO W.S.02.03.02
Swept Straight-Tapered Plane Wings to High Angles of Attack at Subsonic Speeds: spanwise distribution of attainable values, 95025
Theoretical Values for Thin Straight-Tapered Plane Wings at Subsonic Speeds: spanwise distribution and total, 94037, 94038
Use of Analogy for Lift Estimation at Subsonic Speeds: swept non-planar and planar wings to high angle of attack, 96025; swept straight-tapered plane wings to high angle of attack, 95025

Leaks

Control by Seals

see: Reciprocating Seals; Rotary Seals

Drag

due to a discharge into an external stream, 16006

due to a leak into a plenum from an external stream, 18006

Effect on Aerodynamic Characteristics

see: Gap

Mass Flow Rate

into an external stream, 16005

into a plenum from an external stream, 18005

Least Weight Design

see: Flat Panels with Unflanged Integral Stiffeners; Flat Sandwich Panels (Cores of Negligible Flexural Stiffness); Helical Springs of Round Wire; Laminated Construction Using Composites; Struts of I-Section; Struts of Tubular Section

Legendre Polynomials

see also: Quadrature

Algebraic Expressions for, 01011: brief consideration of advantages and limitations for curve fitting and data analysis, 01011

Level

see also: Pressure Spectrum Level

Combination of Decibel Values, 17012, 79037

Level Speed

see: Speed

Lieblein Method

Extreme-Value Analysis

see: Gumbel

Life

see: Crack Propagation; Dry Rubbing Bearings; Endurance (Fatigue Life); Fatigue Life; Fatigue Under Variable Amplitude Loading; Rolling Bearings

Lift

see also: Aerodynamic Loading; Airforce Coefficients; Flutter Derivatives; Interference; Lift Force Due To Pitching (Z_Q or C_zq); Lift Limit; Lift Variation with Control Deflection; Lift-Curve Slope; Maximum Lift; Normal Force; Pressure Distribution; Sideforce; Unsteady Aerodynamics; Wind-Tunnel Corrections for Wings

Aerofoil Design to Optimise Using Multivariate Gradient Search and CFD Codes

introduction to method, 99019

Aerofoils

comparison of results from VGK with experimental results, with/without control deflection, 96028

comparison of results from VGK with results from other theories, 96028

design for low drag over a range of lift coefficient, 99003

discussion of behaviour with fixed transition position of lift-drag polar at subsonic speeds, 00027

estimation at supersonic speeds, AERO W.S.00.03.03, AERO W.S.00.03.05

estimation in viscous subsonic or transonic flow using VGK, 96028, 96029

Aerofoils at High Subsonic Freestream Mach Numbers

discussion of variation in relation to flow features, 90008

Aerofoils at Zero Angle of Attack, 72024, 97020, 98011, TM 4, TM 5

effect of double-slotted flaps, alone or with leading-edge high-lift devices, 94027, 94031

effect of leading-edge high-lift devices alone, 94027

effect of plain flaps, alone or with leading-edge high-lift devices, 94027, 94028

effect of single-slotted flaps, alone or with leading-edge high-lift devices, 94027, 94030

effect of split flaps, alone or with leading-edge high-lift devices, 94027, 94029

effect of triple-slotted flaps, alone or with leading-edge high-lift devices, 94027, 94031

introduction to Data Items on effect of high-lift devices on, 94026

Aerofoils With Sealed Leading- and/or Trailing-Edge Controls or Flaps

effect of deflection in subsonic or transonic flow, 01033, 96028, 96029

Aircraft

increment due to ground effect, 72023

Angle of Attack for Maximum Lift

aerofoils or wings with or without leading- or trailing-edge high-lift devices, 96003

program to predict, 99031

Angle of Attack for Zero Lift

aerofoils in inviscid subcritical flow, 72024, 98011

aerofoils in subcritical attached flow, 98011

cambered and twisted wings, 87031

cambered and twisted wings with approximately circular-section fuselage, 89042

program to predict for low-drag GUNACA-series aerofoils, 99003

Biconvex Aerofoils, AERO W.S.00.03.04

Curve Against Angle of Attack From Zero to Maximum

aerofoils or wings with or without leading- or trailing-edge high-lift devices, 96003

program to predict, 99031

Double-Wedge Aerofoils, AERO W.S.00.03.04, AERO W.S.00.03.05

Elliptical-Section Aerofoils, 79026

Example of Procedure in Calculation of Effects of Propeller Slipstream on Horizontal Tailplane Flow-field, TM 193

Flaps

see: Flaps; Interference; Jet/flap Interference

Missile-Type Wing-Body Combinations

effect of wing height at low incidence in subsonic or supersonic flow, 95009

Similarity Laws at Subsonic or Supersonic Speeds

applied to coefficient in axisymmetric flow, 97025

Similarity Laws at Subsonic, Supersonic or Transonic Speeds

applied to coefficient in two- or three-dimensional flow, 97025

Spoiler (Perforated or Solid) Deflected at Low Speed in Free Air

estimation of decrement with trailing-edge flaps deployed, 14005

estimation of decrement with trailing-edge flaps undeployed, 14004

Spoiler (Solid) Deflected at Low Speed in Ground Effect

estimation of decrement due to, 76026

Swept Non-Planar and Planar Wings to High Angles of Attack at Subsonic Speeds

prediction from leading-edge suction analogy, 96025

Swept Straight-Tapered Plane Wings to High Angles of Attack at Subsonic Speeds

prediction from leading-edge suction analogy, 95025

Two Staggered Lifting Surfaces Trimmed With Given Static Margin

program for calculation, 81023

Vectored-Jet-Thrust Aircraft

example of jet-induced loss in free air, 87037

example of variation of lift in ground effect, 87037

Viscous Full-potential (VFP) Method for Three Dimensional Wings and Wing-body Combinations

estimation of excrescence drag at subsonic speeds and analysis program, 23013

Wing/Flap/Nacelle Combination Submerged in Propeller Slipstream

for multi-propellers on straight wing, 88031

Wings at Zero Angle of Attack With Full- or Part-Span Flaps, 93019, 95021, 96032, 97002, 97009, 97011

effect of drooped leading edge, slats or sealed slats, 96032

effect of Kruger, vented or unvented, 96032

introduction to Data Items on, 97002

Wings at Zero Angle of Attack With Leading-Edge Full- or Part-Span High-Lift Devices, 96032

effect of double-slotted flaps, 95021, 96032, 97002

effect of plain flaps, 96032, 97002, 97011

effect of single-slotted flaps, 93019, 96032, 97002

effect of split flaps, 96032, 97002, 97009

effect of triple-slotted flaps, 95021, 96032, 97002

introduction to Data Items on, 97002

Wings to High Angles of Attack at Subsonic Speeds

program for non-planar and planar, 96025

straight-tapered planar, 95025

Lift-Curve Slope

see also: Normal-Force-Curve Slope

Aerofoils

approximate theoretical expressions for, AERO W.S.00.03.03, AERO W.S.00.03.04

effect of separation characteristics at low speed on, 66034

in inviscid subcritical flow, 72024, TM 4, TM 5

in subcritical compressible flow, 97020

prediction of initial non-linearity without high-lift devices, 88030

prediction of non-linear with high-lift devices deployed, 96003

program to predict minimum for subcritical speeds, 06020

Annular Wings, 77012

Effect of Cut-Out, AERO W.01.01.04

Fins

see: Sideforce Due To Sideslip (Y_v or C_{y β})

Isolated Lifting Surfaces

supersonic, AERO A.S.01.03.02

Missile-Type Wing-Body Combinations

mid-wing configuration at low incidence in subsonic or supersonic flow, 91007

Tailplane

estimation for fin- or body-mounted in subcritical flow, 89029

Wings

prediction of initial non-linearity for plane or non-planar without high-lift devices, 88030

prediction of non-linear with high-lift devices deployed, 96003

subsonic flow, 70011, 95010, TM 169

supersonic flow, 70012

Lift Dependent Drag

see also: Boundary Layer Lift Dependent Drag; Profile Drag; Trailing Vortex Drag

Estimation of Increment Due to Deployment of Perforated or Solid Spoiler, 96026: including effect of downwash at spoiler due to flap deployment, 96026
Introduction, 66031
Program for Swept Non-Planar and Planar Wings to High Angles of Attack at Subsonic Speeds: prediction from leading-edge suction and viscous axial force, 96025
Swept Straight-Tapered Plane Wings at Supersonic Speeds, AERO W.S.02.03.02
Swept Straight-Tapered Plane Wings to High Angles of Attack at Subsonic Speeds: prediction from leading-edge suction and viscous axial force, 95025