Introduction to Aircraft Stability and Control Course Notes for M&AE 5070
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6. Aerodynamic-Center Considerations of Wings I
m 6. AERODYNAMIC-CENTER CONSIDERATIONS OF WINGS I AND WING-BODY COMBINATIONS By John E. Lsmar and William J. Afford, Jr. NASA Langley Research Center SUMMARY Aerodynamic-center variations with Mach number are considered for wings of different planform. The normalizing parameter used is the square root of the wing area, which provides a more meaningful basis for comparing the aerodynamic-center shifts than does the mean geometric chord. The theoretical methods used are shown to be adequate for predicting typical aerodynamlc-center shifts, and ways of minimizing the shifts for both fixed and variable-sweep wings are presented. INTRODUCTION In the design of supersonic aircraft, a detailed knowledge of the aerodynamlc-center position is important in order to minimize trim drag, maximize load-factor capability, and provide acceptable handling qualities. One of the principal contributions to the aerodynamic-center movement is the well-known change in load distributionwithMach number in going from subsonic to supersonic speeds. In addition, large aerodynamic-center var- iations are quite often associated with variable-geometry features such as variable wing sweep. The purpose of this paper is to review the choice of normalizing param- eters and the effects of Mach number on the aerodynamic-center movement of rigid wing-body combinations at low lift. For fixed wings the effects of both conventional and composite planforms on the aerodynamic-center shift are presented, and for variable-sweepwings the characteristic movements of aerodynamlc-center position wlth pivot location and with variable-geometry apex are discussed. Since systematic experimental investigations of the effects of planform on the aerodynamic-center movement with Mach number are still limited, the approach followed herein is to establish the validity of the computative processes by illustrative comparison wlth experiment and then to rely on theory to show the systematic variations. -
How Planes Fly ! Marymoor R/C Club, Redmond, WA! AMA Charter 1610!
How Planes Fly ! Marymoor R/C Club, Redmond, WA! AMA Charter 1610! Version 2.0 – Nov 2018! Page 1! Controls, Aerodynamics, and Stability • Elevator, Rudder, Aileron! • Wing planform! • Lift and Wing Design! • Wing section (airfoil)! • Tail group (empennage)! • Center of lift, center of gravity! • Characteristics of a “speed stable” airplane! Page 2! Ailerons, Elevators, and Rudder! Control Roll, Pitch, and Yaw! Ailerons! • Roll, left and right! Elevators! • Pitch, up and down) ! Rudder! • Yaw, left and right! Page 3! Radio Controls! Elevator! Power! (Pitch)! Rudder! Ailerons! (yaw)! (roll)! Trim Controls! Page 4! Wing Planform! • Rectangular (best for trainers)! • Tapered! • Elliptical! • Swept! • Delta! Page 5! Lift! Lift! Lift comes from:! • Angle of Attack! Drag! • Wing Area! Direction of flight! • Airfoil Shape ! • Airspeed! Weight! In level flight, Lift = Weight! Page 6! Lift is greatly reduced when the Wing Stalls! • Stall can occur when:! • Too slow! • Pulling too much up elevator! • Steep bank angle! • Any combination of these three! • Occurs at critical angle of attack, about 15 degrees ! • Trainers have gentle stall characteristics. The warbird you want to fly someday might not.! • One wing can stall before the other, resulting in a sharp roll, and if it continues, a spin. A good trainer won’t do this.! Page 7! Airfoil Shapes! Flat bottom airfoil! “Semi-symmetrical” airfoil! • much camber (mid-line is curved)! • has some camber ! • Often used on trainers and Cubs! • sometimes used on trainers! • Good at low speeds! • Good all-around -
CANARD.WING LIFT INTERFERENCE RELATED to MANEUVERING AIRCRAFT at SUBSONIC SPEEDS by Blair B
https://ntrs.nasa.gov/search.jsp?R=19740003706 2020-03-23T12:22:11+00:00Z NASA TECHNICAL NASA TM X-2897 MEMORANDUM CO CN| I X CANARD.WING LIFT INTERFERENCE RELATED TO MANEUVERING AIRCRAFT AT SUBSONIC SPEEDS by Blair B. Gloss and Linwood W. McKmney Langley Research Center Hampton, Va. 23665 NATIONAL AERONAUTICS AND SPACE ADMINISTRATION • WASHINGTON, D. C. • DECEMBER 1973 1.. Report No. 2. Government Accession No. 3. Recipient's Catalog No. NASA TM X-2897 4. Title and Subtitle 5. Report Date CANARD-WING LIFT INTERFERENCE RELATED TO December 1973 MANEUVERING AIRCRAFT AT SUBSONIC SPEEDS 6. Performing Organization Code 7. Author(s) 8. Performing Organization Report No. L-9096 Blair B. Gloss and Linwood W. McKinney 10. Work Unit No. 9. Performing Organization Name and Address • 760-67-01-01 NASA Langley Research Center 11. Contract or Grant No. Hampton, Va. 23665 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address Technical Memorandum National Aeronautics and Space Administration 14. Sponsoring Agency Code Washington , D . C . 20546 15. Supplementary Notes 16. Abstract An investigation was conducted at Mach numbers of 0.7 and 0.9 to determine the lift interference effect of canard location on wing planforms typical of maneuvering fighter con- figurations. The canard had an exposed area of 16.0 percent of the wing reference area and was located in the plane of the wing or in a position 18.5 percent of the wing mean geometric chord above the wing plane. In addition, the canard could be located at two longitudinal stations. -
CHAPTER TWO - Static Aeroelasticity – Unswept Wing Structural Loads and Performance 21 2.1 Background
Static aeroelasticity – structural loads and performance CHAPTER TWO - Static Aeroelasticity – Unswept wing structural loads and performance 21 2.1 Background ........................................................................................................................... 21 2.1.2 Scope and purpose ....................................................................................................................... 21 2.1.2 The structures enterprise and its relation to aeroelasticity ............................................................ 22 2.1.3 The evolution of aircraft wing structures-form follows function ................................................ 24 2.2 Analytical modeling............................................................................................................... 30 2.2.1 The typical section, the flying door and Rayleigh-Ritz idealizations ................................................ 31 2.2.2 – Functional diagrams and operators – modeling the aeroelastic feedback process ....................... 33 2.3 Matrix structural analysis – stiffness matrices and strain energy .......................................... 34 2.4 An example - Construction of a structural stiffness matrix – the shear center concept ........ 38 2.5 Subsonic aerodynamics - fundamentals ................................................................................ 40 2.5.1 Reference points – the center of pressure..................................................................................... 44 2.5.2 A different -
An Aerodynamic Comparative Analysis of Airfoils for Low-Speed Aircrafts
Published by : International Journal of Engineering Research & Technology (IJERT) http://www.ijert.org ISSN: 2278-0181 Vol. 5 Issue 11, November-2016 An Aerodynamic Comparative Analysis of Airfoils for Low-Speed Aircrafts Sumit Sharma B.E. (Mechanical) MPCCET, Bhilai, C.G., India M.E. (Thermal) SSCET, SSGI, Bhilai, C.G., India Abstract - This paper presents investigation on airfoil S1223, NACA4412 at specified boundary conditions, A S819, S8037 and S1223 RTL at low speeds to find out the most comparison is done between results obtained from CFD suitable airfoil design to be used in the low speed aircrafts. simulation in ANSYS and results obtained from an The method used for analysis of airfoils is Computational experiment done in the wind tunnel. The comparative Fluid Dynamics (CFD). The numerical simulation of low result shows that, the result from experiment and from speed and high-lift airfoil has been done using ANSYS- FLUENT (version 16.2) to obtain drag coefficient, lift CFD simulation showing close agreement between these coefficient, coefficient of moment and Lift-to-Drag ratio over two methods. So, the CFD simulation using ANSYS- the airfoils for the comparative analysis of airfoils. The S1223 FLUENT can be used as an relative alternative to RTL airfoil has been chosen as the most suitable design for experimental method in determining drag and lift. the specified boundary conditions and the Mach number from 0.10 to 0.30. Jasminder Singh et al [2] (June- 2015), Analysis is done on NACA 4412 and Seling 1223 airfoils using Computational Key words: CFD, Lift, Drag, Pitching, Lift-to-Drag ratio. -
Lifting Surface Lift and Pitch Considerations
Stability and Control Some Characteristics of Lifting Surfaces, and Pitch-Moments The lifting surfaces of a vehicle generally include the wings, the horizontal and vertical tail, and other surfaces such as canards, winglets, etc. What they all have in common is that there purpose is to create an aerodynamic force and moment. Whether the surface is infinite (2-D) or finite (3-D), we can assign to it a force and moment. Usually we designate a 2-D lifting surface as an airfoil, and a 3-D lifting surface as a wing (or tail, or winglet, of whatever). Here all lifting surfaces will be assigned the name - wing. Generally the information concerning forces and moments on a wing are determined from wind tunnel tests or from computer codes. Unlike a force, a moment must be referred to a specific reference point. Often time the information given is not referenced to the point of your interest. Consequently we would like to be able to convert results referenced to one point to equivalent information with respect to a different reference point. We will later use these same ideas applied to a complete aircraft. Consider two identical wings mounted in a wind tunnel. One wing is supported at point A, and the other at point B. At each of these support points there is an electronic “balance” used to measure the forces and moments acting on the wing at those respective points. For simplicity the wings will be represented as flat plates. Si nce the wings are identical we can expect that the aerodynamic forces will be the same. -
Actuator Saturation Analysis of a Fly-By-Wire Control System for a Delta-Canard Aircraft
DEGREE PROJECT IN VEHICLE ENGINEERING, SECOND CYCLE, 30 CREDITS STOCKHOLM, SWEDEN 2020 Actuator Saturation Analysis of a Fly-By-Wire Control System for a Delta-Canard Aircraft ERIK LJUDÉN KTH ROYAL INSTITUTE OF TECHNOLOGY SCHOOL OF ENGINEERING SCIENCES Author Erik Ljudén <[email protected]> School of Engineering Sciences KTH Royal Institute of Technology Place Linköping, Sweden Saab Examiner Ulf Ringertz Stockholm KTH Royal Institute of Technology Supervisor Peter Jason Linköping Saab Abstract Actuator saturation is a well studied subject regarding control theory. However, little research exist regarding aircraft behavior during actuator saturation. This paper aims to identify flight mechanical parameters that can be useful when analyzing actuator saturation. The studied aircraft is an unstable delta-canard aircraft. By varying the aircraft’s center-of- gravity and applying a square wave input in pitch, saturated actuators have been found and investigated closer using moment coefficients as well as other flight mechanical parameters. The studied flight mechanical parameters has proven to be highly relevant when analyzing actuator saturation, and a simple connection between saturated actuators and moment coefficients has been found. One can for example look for sudden changes in the moment coefficients during saturated actuators in order to find potentially dangerous flight cases. In addition, the studied parameters can be used for robustness analysis, but needs to be further investigated. Lastly, the studied pitch square wave input shows no risk of aircraft departure with saturated elevons during flight, provided non-saturated canards, and that the free-stream velocity is high enough to be flyable. i Sammanfattning Styrdonsmättning är ett välstuderat ämne inom kontrollteorin. -
05 Longitudinal Stability Derivatives
Flight Dynamics and Control Lecture 5: Longitudinal stability Derivatives G. Dimitriadis University of Liege 1 Previously on AERO0003-1 • We developed linearized equations of motion Longitudinal direction " % "m 0 0 0 0% " v % −Yv −(Yp + mWe ) −(Yr − mUe ) −mgcosθe −mgsinθe " v % " Yξ Yς % $ ' $ ' $ ' $ ' $ ' 0 I x −I xz 0 0 p $ −L −L −L 0 0 ' p Lξ Lς $ ' $ ' v p r $ ' $ ' "ξ% $ ' $ ' $ ' $ ' $ ' 0 −I xz Iz 0 0 r + −N −N −N 0 0 r = Nξ Nς $ ' $ ' $ ' $ v p r ' $ ' $ ' #ς & $ 0 0 0 1 0' $ϕ ' $ 0 −1 0 0 0 ' $ϕ ' $ 0 0 ' $ ' #$ 0 0 0 0 1&' #$ψ &' − #$ψ &' $ 0 0 ' # 0 Lateral0 direction1 0 0 & # & " % " − − − − θ % m −Xw 0 0 "u % Xu Xw (Xq mWe ) mgcos e "u % " X X % $ ' $ ' η τ $ ' $ ' $ ' $ 0 m − Z 0 0' w $ − − − + θ ' w Zη Zτ "η% ( w ) $ ' + Zu Zw (Zq mUe ) mgsin e $ ' = $ ' $ ' $ ' $ ' $ ' − $ q ' $ q ' Mη Mτ #τ & $ 0 M w I y 0' $−M u −M w −M q 0 ' $ ' $ ' $ ' $ 0 0 0 1' #θ & $ − ' #θ & # 0 0 & 2 # & # 0 0 1 0 & Longitudinal stability derivatives • It has already been stated that the best way to obtain the values of the stability derivatives is to measure them. • However, it is still useful to discuss simplified methods of estimating these coefficients. • Such estimates can be used, for example, in the preliminary design of aircraft. • This lecture will treat longitudinal stability derivatives. 3 Simple example • We keep the quasi-steady aerodynamic assumption. • Assume that the lift of an aircraft lies entirely in the z direction: 1 2 Z = ρU SCL 2 • where CL is the lift coefficient, assumed to be constant in this simple example. -
09 Stability and Control
Aircraft Design Lecture 9: Stability and Control G. Dimitriadis Introduction to Aircraft Design Stability and Control H Aircraft stability deals with the ability to keep an aircraft in the air in the chosen flight attitude. H Aircraft control deals with the ability to change the flight direction and attitude of an aircraft. H Both these issues must be investigated during the preliminary design process. Introduction to Aircraft Design Design criteria? H Stability and control are not design criteria H In other words, civil aircraft are not designed specifically for stability and control H They are designed for performance. H Once a preliminary design that meets the performance criteria is created, then its stability is assessed and its control is designed. Introduction to Aircraft Design Flight Mechanics H Stability and control are collectively referred to as flight mechanics H The study of the mechanics and dynamics of flight is the means by which : – We can design an airplane to accomplish efficiently a specific task – We can make the task of the pilot easier by ensuring good handling qualities – We can avoid unwanted or unexpected phenomena that can be encountered in flight Introduction to Aircraft Design Aircraft description Flight Control Pilot System Airplane Response Task The pilot has direct control only of the Flight Control System. However, he can tailor his inputs to the FCS by observing the airplane’s response while always keeping an eye on the task at hand. Introduction to Aircraft Design Control Surfaces H Aircraft control -
Longitudinal & Lateral Directional Short Course
1 Longitudinal & Lateral Directional Short Course Flight One – Effects of longitudinal stability and control characteristics on handling qualities Background: In this flight training exercise we will examine how longitudinal handling qualities are affected by three important variables that are inherent in a given aircraft design. They are: Static longitudinal stability Dynamic longitudinal stability Elevator control effectiveness As you will recall from your classroom briefings, longitudinal stability is responsible for the frequency response to a disturbance, which can be caused by the atmosphere or an elevator control input. It may be described by two longitudinal oscillatory modes of motion: A Long term response (Phugoid), which is a slow or low frequency oscillation, occurring at a relatively constant angle of attack with altitude and speed variations. This response largely affects the ability to trim for a steady state flight condition. A short term response where a higher frequency oscillation occurs at a relatively constant speed and altitude, but with a change in angle of attack. This response is associated with maneuvering the aircraft to accomplish a closed loop task, such as an instrument approach procedure. If static stability is positive; The long and short period responses will either be convergent or neutral (oscillations) depending on dynamic stability If neutral; The long period will no longer be oscillatory and short period pitch responses will decay to a pitch rate response proportional to the amount of elevator input; If slightly negative (Equivalent of moving CG behind the stick fixed neutral point); In the long period, elevator stick position will reverse, i.e., as speed increases a pull will be required on the elevator followed by a push, and as speed decreases, a push will be required followed by a pull The short period responses will result in a continuous divergence from the trim state. -
Equations for the Application of to Pitching Moments
https://ntrs.nasa.gov/search.jsp?R=19670002485 2020-03-24T02:43:10+00:00Z View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by NASA Technical Reports Server NASA TECHNICAL NOTE NASA TN D-3738 00 M h U GPO PRICE $ c/l U z CFSTl PRICE@) $ ,2biJ I 1 Hard copy (HC) ' (THRU) :: N67(ACCES~ION 11814NUMBER) 5P Microfiche (MF) > Jo(PAGES1 k i ff 853 July 85 2 (NASA CR OR TMX OR AD NUMBER) '- ! EQUATIONS FOR THE APPLICATION OF * WIND-TUNNEL WALL CORRECTIONS TO PITCHING MOMENTS CAUSED BY THE TAIL OF AN AIRCRAFT MODEL by Harry He Heyson Langley Research Center Langley Stdon, Hampton, Vk NATIONAL AERONAUTICS AND SPACE ADMINISTRATION WASHINGTON, D. C. NOVEMBER 1966 . NASA TN D-3738 EQUATIONS FOR THE APPLICATION OF WIND-TUNNEL WALL CORRECTIONS TO PITCHING MOMENTS CAUSED BY THE TAIL OF AN AIRCRAFT MODEL By Harry H. Heyson Langley Research Center Langley Station, Hampton, Va. NATIONAL AERONAUTICS AND SPACE ADMINISTRATION For sale by the Clearinghouse for Federal Scientific and Technical Information Springfield, Virginia 22151 - Price 61.00 , EQUATIONS FOR THE APPLICATION OF WIND-TUNNEL WALL CORmCTIONS TO PITCHING MOMENTS CAUSED BY THE TAIL OF AN AIRCRAFT MODEL By Harry H. Heyson Langley Research Center SUMMARY Equations are derived for the application of wall corrections to pitching moments due to the tail in two different manners. The first system requires only an alteration in the observed pitching moment; however, its application requires a knowledge of a number of quantities not measured in the usual wind- tunnel tests, as well as assumptions of incompressible flow, linear lift curves, and no stall. -
SM11188 Standard Modification Page : 1 of 6 Issue 1 Compiled : S Brown Approved : F Donaldson
Mod No. SM11188 Standard Modification Page : 1 of 6 Issue 1 Compiled : S Brown Approved : F Donaldson TITLE : Main Wing Trailing Edge Flow Straighteners AIRCRAFT TYPE : Vari-Eze Mod Type: Retro-fit 1. Introduction The Rutan Aircraft Factory approved the (later to be mandatory) installation of leading edge vortilons on all Vari-Ezes in the October 1984 edition of the Canard Pusher ( CP 42 pages 5/6) to improve the swept main wing stall margins, increase visibility over the nose on final approach and enable reduced approach speeds without the risk of low speed wing rock or deep stall. The vortilons generate vortices over the main wing at high angles of attack that reduce lift-losing span-wise flow. There is negligible speed or drag penalty Flow straighteners positioned on the trailing edge of the swept main wing further reduce span wise flow at high angles of attack. It has been demonstrated that the addition of trailing edge flow straighteners enable the wing to produce more lift at a given angle of attack enabling lower approach speeds with no loss of view over the nose. The result is a reduced sink rate for a given airspeed and an increased margin between main wing and canard stall speeds. 2. Parts List Qty Part No. Description Source 2 SM11188-1 Outboard Fence Manufacture 2 SM11188-2 Middle Fence Manufacture 2 SM11188-3 Inboard Fence Manufacture White RTV Silicone Hardware store Flocked Cotton / BID / Aircraft Spruce Epoxy Resin List of related drawings / photos Drawing No. Title / Description Issue SM11188-D1 Drawing of Flow Straighteners dimensions SM11188-D2 Drawing of installation on main wing and fitting detail SM11188-D3 Photograph of Gary Hertzler’s fences installation on N99VE 3.