Introduction PRINCIPLES of FLIGHT AEROPLANES
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PRINCIPLES of FLIGHT Introduction AEROPLANES © Oxford Aviation Academy (UK) Limited 2008 All Rights Reserved This text book is to be used only for the purpose of private study by individuals and may not be reproduced in any form or medium, copied, stored in a retrieval system, lent, hired, rented, transmitted or adapted in whole or in part without the prior written consent of Oxford Aviation Academy. Copyright in all documents and materials bound within these covers or attached hereto, excluding that material which is reproduced by the kind permission of third parties and acknowledged as such, belongs exclusively to Oxford Aviation Academy. Certain copyright material is reproduced with the permission of the International Civil Aviation Organisation, the United Kingdom Civil Aviation Authority and the European Aviation Safety Agency (EASA). This text book has been written and published as a reference work to assist students enrolled on an approved EASA Air Transport Pilot Licence (ATPL) course to prepare themselves for the EASA ATPL theoretical knowledge examinations. Nothing in the content of this book is to be interpreted as constituting instruction or advice relating to practical flying. Whilst every effort has been made to ensure the accuracy of the information contained within this book, neither Oxford Aviation Academy nor the distributor gives any warranty as to its accuracy or otherwise. Students preparing for the EASA ATPL theoretical knowledge examinations should not regard this book as a substitute for the EASA ATPL theoretical knowledge training syllabus published in the current edition of ‘CS-FCL 1 Flight Crew Licensing (Aeroplanes)’ (the Syllabus). The Syllabus constitutes the sole authoritative definition of the subject matter to be studied in an EASA ATPL theoretical knowledge training programme. No student should prepare for, or is currently entitled to enter himself/herself for the EASA ATPL theoretical knowledge examinations without first being enrolled in a training school which has been granted approval by an EASA authorised national aviation authority to deliver EASA ATPL training. Oxford Aviation Academy excludes all liability for any loss or damage incurred or suffered as a result of any reliance on all or part of this book except for any liability for death or personal injury resulting from Oxford Aviation Academy’s negligence or any other liability which may not legally be excluded. Cover Photograph: Boeing 747 Photographed by Josef Willems, www.joe-willems.com This edition distributed by Transair (UK) Ltd, Shoreham, England: 2008 Printed in Singapore by KHL Printing Co. Pte Ltd ii PRINCIPLES of FLIGHT Introduction AEROPLANES Textbook Series Book Title EASA Ref. No. Subject 1 010 Air Law 010 2 020 Aircraft General Knowledge 1 021 01 Airframes & Systems 021 01 01-04 Fuselage, Wings & Stabilising Surfaces 021 01 05 Landing Gear 021 01 06 Flight Controls 021 01 07 Hydraulics 021 01 08-09 Air Systems & Air Conditioning 021 01 10 Anti-icing & De-icing 021 01 11 Fuel Systems 021 04 00 Emergency Equipment 3 020 Aircraft General Knowledge 2 021 02 Electrics – Electronics 021 02 01 Direct Current 021 02 02 Alternating Current 021 02 05 Basic Radio Propagation. 4 020 Aircraft General Knowledge 3 021 00 Powerplant 021 03 01 Piston Engines 021 03 02 Gas Turbines 5 020 Aircraft General Knowledge 4 022 Instrumentation 022 01 Flight Instruments 022 03 Warning & Recording 022 02 Automatic Flight Control 022 04 Power Plant & System Monitoring Instruments 6 030 Flight Performance & Planning 1 031 Mass & Balance 032 Performance 7 030 Flight Performance & Planning 2 033 Flight Planning & Monitoring 8 040 Human Performance & Limitations 040 9 050 Meteorology 050 10 060 Navigation 1 061 General Navigation 11 060 Navigation 2 062 Radio Navigation 12 070 Operational Procedures 070 13 080 Principles of Flight 080 14 090 Communications 091 VFR Communications 092 IFR Communications iii PRINCIPLES of FLIGHT Introduction AEROPLANES iv PRINCIPLES of FLIGHT Introduction AEROPLANES Contents OVERVIEW AND DEFINITIONS . 1 THE ATMOSPHERE . 23 BASIC AERODYNAMIC THEORY. 41 SUBSONIC AIRFLOW . 51 LIFT . 69 DRAG . .109 STALLING . .143 HIGH LIFT DEVICES . .207 AIRFRAME CONTAMINATION . 231 STABILITY and CONTROL. .239 CONTROLS. .331 FLIGHT MECHANICS . 363 HIGH SPEED FLIGHT . 405 LIMITATIONS . 457 WINDSHEAR . 487 PROPELLERS. .503 REVISION QUESTIONS . 525 v PRINCIPLES of FLIGHT Introduction AEROPLANES vi Overview and Definitions Chapter 1 CHAPTER ONE OVERVIEW AND DEFINITIONS Contents OVERVIEW. 3 GENERAL DEFINITIONS . 7 GLOSSARY . 10 LIST OF SYMBOLS . 14 SELF ASSESSMENT QUESTIONS . 15 ANSWERS . 22 1 Chapter 1 Overview and Definitions 2 Overview and Definitions Chapter 1 OVERVIEW The primary requirements of an aircraft are as follows: A wing to generate a lift force. A fuselage to house the payload. Tail surfaces to add stability. Control surfaces to change the direction of flight and, Engines to make it go forward. The process of lift generation is fairly straightforward and easy to understand. Over the years aircraft designers, aerodynamicists and structural engineers have refined the basics and by subtle changes of shape and configuration have made maximum use of the current understanding of the physical properties of air to produce aircraft best suited to a particular role. Aircraft come in different shapes and sizes, usually, each designed for a specific task. All aircraft share certain features, but to obtain the performance required by the operator the designer will configure each type of aeroplane in a specific way. As can be seen from the illustrations on the facing page, the position of the features shared by all types of aircraft - i.e. wings, fuselage, tail surfaces and engines varies from type to type. Why are wing plan shapes different? Why are wings mounted sometimes on top of the fuselage instead of the bottom? Why are wings mounted in that position and at that angle? Why is the horizontal stabiliser mounted sometimes high on top of the fin rather than on either side of the rear fuselage? Every feature has a purpose and is never included merely for reasons of style. 3 Chapter 1 Overview and Definitions An aeroplane, like all bodies, has mass. With the aircraft stationary on the ground it has only the force due to the acceleration of gravity acting upon it. This force, its WEIGHT, acts vertically downward at all times. W FigureThe 1.1 Force The of Force Weight of Weight Before an aeroplane can leave the ground and fly the force of weight must be balanced by a force which acts upwards. This force is called LIFT. The lift force must be increased until it is the same as the aeroplane’s weight. L W The Forces of Weight and Lift Figure 1.2 The Forces of Weight and Lift 4 Overview and Definitions Chapter 1 To generate a lift force the aeroplane must be propelled forward through the air by a force called THRUST, provided by the engine(s). L W Figure 1.3 The Forces of Weight, Lift and The Forces of Weight,Thrust Lift and Thrust From the very moment the aeroplane begins to move, air resists its forward motion with a force called DRAG. L W TheFigure Forces 1.4 of Weight, The Forces Lift, ofThrust Weight, and Lift, Drag Thrust and Drag 5 Chapter 1 Overview and Definitions When an aeroplane is moving there are four main forces acting upon it:- WEIGHT, LIFT, THRUST and DRAG. These are all closely interrelated. i.e.:- The greater the weight - the greater the lift requirement. The greater the lift - the greater the drag. The greater the drag - the greater the thrust required, and so on... Air has properties which change with altitude. Knowledge of these variables, together with their effect on an aeroplane, is a prerequisite for a full understanding of the principles of flight. The structural and aerodynamic design of an aeroplane is a masterpiece of compromise. An improvement in one area frequently leads to a loss of efficiency in another. An aeroplane does not ‘grip’ the air as a car does the road. An aeroplane is often not pointing in the same direction in which it is moving. 6 Overview and Definitions Chapter 1 GENERAL DEFINITIONS Mass Unit - Kilogram (kg) - ‘The quantity of matter in a body.’ The mass of a body is a measure of how difficult it is to start or stop. (a “body”, in this context, means a substance. Any substance; a gas, a liquid or a solid.) The larger the mass, the greater the FORCE required to start or stop it in the same distance. Mass has a big influence on the time and/or distance required to change the direction of a body. Force Unit - Newton (N) - ‘A push or a pull’. That which causes or tends to cause a change in motion of a body. There are four forces acting on an aircraft in flight - pushing or pulling in different directions. Weight Unit - Newton (N) - ‘The force due to gravity’. ( F = m x g ) Where (m) is the mass of the object and (g) is the acceleration due to the gravity constant, which has the value of 9.81 m/s2. ( A 1 kg mass ‘weighs’ 9.81 newtons ) If the mass of a B737 is 60,000 kg and F = m x g it is necessary to generate: [60,000 kg x 9.81 m/s2] 588,600 N of lift force. Centre of Gravity (CG) The point through which the weight of an aircraft acts. An aircraft in flight is said to rotate around its CG. The CG of an aircraft must remain within certain forward and aft limits, for reasons of both stability and control. Work Unit - Joule (J) - A force is said to do work on a body when it moves the body in the direction in which the force is acting.