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    Aerodynamics Class 1

    Uploaded by

    Rene Queiroz
    This document discusses key aerodynamic concepts related to rotary wing aircraft. It covers topics such as relative wind, lift and drag forces, airflow patterns during hover and forward flight, retreating blade stall, compressibility effects, vortex ring state, blade flapping and lead-lag motions, dissymmetry of lift, dynamic rollover, and hovering attitudes. The document provides definitions and diagrams to explain how these concepts impact helicopter performance and stability.

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    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd

    Aerodynamics Class 1

    Uploaded by

    Rene Queiroz
    108 views21 pages
    This document discusses key aerodynamic concepts related to rotary wing aircraft. It covers topics such as relative wind, lift and drag forces, airflow patterns during hover and forward flight, retreating blade stall, compressibility effects, vortex ring state, blade flapping and lead-lag motions, dissymmetry of lift, dynamic rollover, and hovering attitudes. The document provides definitions and diagrams to explain how these concepts impact helicopter performance and stability.

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    This document discusses key aerodynamic concepts related to rotary wing aircraft. It covers topics such as relative wind, lift and drag forces, airflow patterns during hover and forward flight, retreating blade stall, compressibility effects, vortex ring state, blade flapping and lead-lag motions, dissymmetry of lift, dynamic rollover, and hovering attitudes. The document provides definitions and diagrams to explain how these concepts impact helicopter performance and stability.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    108 views21 pages

    Aerodynamics Class 1

    Uploaded by

    Rene Queiroz
    This document discusses key aerodynamic concepts related to rotary wing aircraft. It covers topics such as relative wind, lift and drag forces, airflow patterns during hover and forward flight, retreating blade stall, compressibility effects, vortex ring state, blade flapping and lead-lag motions, dissymmetry of lift, dynamic rollover, and hovering attitudes. The document provides definitions and diagrams to explain how these concepts impact helicopter performance and stability.

    Copyright:

    Attribution Non-Commercial (BY-NC)
    Download as PPT, PDF, TXT or read online from Scribd
    Download as ppt, pdf, or txt
    You are on page 1of 21

    Rotary Wing AERODYNAMICS

    Aerodynamics

    Airfoil Force Vectors

    Aerodynamics

    Aerodynamic Terms
    Rotational Relative Wind
    Opposes Direction of Blade Rotation in Tip Path Plane

    Induced Flow
    Vertical Component of Airflow Drawn Through the Rotor System

    Resultant Relative Wind


    Actual ind that Acts on the Airfoil (Vector Sum of Rotational Relative Wind & Induced Flow)

    Angle of Incidence
    Angle Between Chord !ine " Rotational Relati#e $Tip Path Plane%
    Aerodynamics

    ind
    3

    Aerodynamic Terms (Cont)


    Angle of Attack
    Angle Between Chord !ine " Resultant Relati#e ind

    Lift
    Acts Perpendicular to Resultant Relati#e ind

    Drag
    Acts Parallel " Opposite to Resultant Relati#e ind

    otal Aerodynamic Force


    Vector Sum of Airfoil !ift " Drag

    Aerodynamics

    Lift
    "ressure Differential
    Between &pper " !ower Airfoil Surfaces Creates !ift

    Lift #$uation

    L = 2 V 2 SC L

    %am&ered Airfoil in "ositive Lift

    Aerodynamics

    Drag
    y(es of Drag
    ' Induced) Caused (y the Production of !ift ' "arasite) All Drag )ot Caused (y !ift
    * "rofile) Parasitic Drag of Rotor Blades Passing Through the Air

    Drag #$uation

    D = 2 V 2 SC D

    Largest %ontri&utor to otal Drag


    ' Low *(eed) +nduced Drag ' +ig, *(eed) Parasite,Profile Drag

    Aerodynamics

    '

    Helicopter Drag vs. Airspeed

    Aerodynamics

    Airflow At A Hover - OGE

    Aerodynamics

    Airflow At A Hover - IGE

    Aerodynamics

    Translating Tendency
    endency of Aircraft to Drift In t,e Direction of ail Rotor ,rust at a +over

    %om(ensated for &y 1i2ing 3nit 4 "ilot In(ut

    Aerodynamics

    10

    Dissymmetry of Lift
    Difference in Lift Associated wit, t,e Advancing 4 Retreating *ides of t,e Rotor *ystem %om(ensated for &y 5lade Fla((ing 4 %yclic Feat,ering

    Aerodynamics

    11

    Blade Flapping
    3(6Down 1ovement of t,e Rotor 5lade A&out A Fla((ing +inge %auses 5low&ack 7Rearward ilt of Rotor Disk8

    Aerodynamics

    12

    Blade Lead & Lag (Hunting)


    Fore 4 Aft 1ovement of t,e 5lade in i( "at, "lane Due to %,anges in 5lade *(eed %oriolis #ffect
    Angular Velocity Changes with Blade C-

    Aerodynamics

    13

    Retreating Blade Stall


    9ut&oard *ection of Retreating 5lade *talls at +ig, Forward Airs(eed %auses
    Blade .lapping " Cyclic .eathering that /0ceed Critical Angle

    Aircraft "itc,es 3( 4 Rolls Left %onditions %onducive to Retreating 5lade *tall


    1 2igh - T 1 2igh DA 1 Tur(ulent Air
    Aerodynamics

    1 !ow Rotor RP3 1 2igh 4-5 3aneu#ers

    14

    Retreating Blade Stall

    Aerodynamics

    1!

    Compressibility
    9ut&oard *ection of Advancing 5lade #2ceeds t,e *(eed of *ound at +ig, Airs(eed Aerodynamic %enter 1oves Aft
    !arge Down Pitching 3oment at Out(oard Tip Structural .ailure of Blade ill Cause

    Aircraft "itc,es Down %onditions %onducive to %om(ressi&ility


    1 2igh Airspeed 1 2igh - T 1 !ow Temperature Aerodynamics 1 2igh Rotor RP3 1 2igh DA 1 Tur(ulent Air
    1'

    Settling with Power


    (Vortex Ring State) Formation of an Inner :orte2 on t,e 5lade %auses *u&stantial Loss of Lift Increased %ollective Results in Larger :orte2 Rings 4 +ig,er Rates of Descent %onditions %onducive to *ettling wit, "ower
    ' Very !ow .orward Airspeed ' 6718779 of A#aila(le Power Applied ' :77 ft,min Rate of Descent or -reater

    Recover &y #sta&lis,ing Directional Flig,t


    Aerodynamics

    1-

    Vortex Ring State


    Induced Flow 5efore :orte2 Ring *tate

    :orte2 Ring *tate

    Aerodynamics

    1.

    Offset Hinges

    ends to Align t,e +elico(ter wit, t,e Rotor i( "at, "lane

    9ffset %reates a +u& 1oment


    !arger the Offset; 2igher the 2u( 3oment

    Results in ;reater 1aneuvera&ility 4 Faster Aircraft Res(onse

    Aerodynamics

    1/

    Dynamic Rollover
    Aircraft #2ceeds %ritical Rollover Angle wit, a Rolling 1oment Dynamic Rollover %riteria
    ' Pi#ot Point ' Rolling 3oment ' !ift Component and,or 2u( 3oment

    ail Rotor %ontri&ution

    %ollective is 1ost #ffective %ontrol


    Cyclic is also /ffecti#e Due to Offset 2inges
    Aerodynamics

    20

    Fuselage Hovering Attitude


    <ose +ig,
    ' .orward Tilt of 3ain Transmission ' Aircraft C- Aft of 3ain Rotor 3ast

    Left *ide Low


    ' !eft Cyclic Compensating for Translating Tendency

    Aerodynamics

    21

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