Title EASA Module 12 Helicopter Aerodynamics, Structures and Systems.pdf ✅

K B3810 He//capters He Wharekura-tini Kaihautu 0 Aotearoa THE OPE N P0|.YTE(HN|( OF NEW ZEALAND 555-3-1_ structures and systems Helicopter Aerodynamics Helicopter aerodynamics, structures and systems
CONTENTS Basic Operating Principles Controls Structures The Powertrain Safety In and Around Helicopters Appendix: Table of Definitions Copyright {his material is for the sole use of enrolled students and may not be reproduced without the written authority of the Principal, TOPNZ. 55573/1 “knew --tau
AIRCRAFT ENGINEERING" AIRFRAMES 111 ASSIGNMENT 1 BASIC HELICOPTERS This assignment is intended to serve as an introduction to the rest of the assignments in the 5S5~3 series. The complete series consists of Assignment 1 Basic Helicopters Assignment 2 Basic Flying Controls Assignment 3 Basic Rotors Assignment Q Piston Engine Installations Assignment S Rotating Flying Controls Assignment 6 Main and Tail Rotor Heads and Blades Assignment 7 Transmission Systems Assignment 8 Helicopter Vibrations Assignment 9 Turbine Engine Installations Assignment 10 Basic Helicopter Flight Aerodynamics The word Helicopter is derived from the two Greek words: Helicon = helix Pteron = wing and so literally the word helicopter means spiral wing. The history of helicopter flight starts in the mid 1700s when people of many nationalities began making models of helicopters of all shapes and sizes, powered in a variety of ways, such as gunpowder, steam, and electricity. However, vertical flight was known much earlier. It was first described by the Chinese alchemist Ko—Hung, who wrote in 320 AD about a toy now known as the "Chinese flying top". In 1907, Paul Carnu, a Frenchman, made the world's first free helicopter flight. His machine reached a height of about 1.7 metres 555/3/1 8/Q) .w
_ 2 _ and was airborne for but a'few seconds. In the years that followe many helicopters were made and flown. In 1936, the successful Focke-Wulf Fw 61 flew for the first time. In 1939, Igor Sikorsky flew his VS 300, which became the RH production model and is the forerunner of the present—day Sikorsky helicopter models. Many of the advances made in the design of the helicopter rotor are due to the work of Juan de La Cierva who, during the development of his "autogyro" re~invented the flapping hinge, invented the drag hinge and its damper, and developed cyclic pitch control of the rotor. So far, several terms associated with helicopters have been used. Before going any further, and to avoid confusion, a list of words and terms as they are used on helicopters and on fixed-wing aircraft is given in the Appendix at the end of this assignment. As part of your work on this assignment you should now read the Appendix and than dg Practice Exercise A that follows here. PRACTICE EXERCISE A State whether each of the following statements is True or False. 1. Disc area is the sum of the area of all the blades of a rotor. 2. The angle between the chord line of a rotor blade and its plane of rotation is called the angle of incidence. 3. The control that changes the main rotor blade pitch angles all together is the cyclic pitch control 4. An aircraft pitches about its longitudinal axis. S. The propulsion rotor sited at the tail in a more or less vertical plane is the tail rotor- 6. An aircraft yaws about its normal axis. 7. The study of the motion of air is called dynamics. 8. The control that changes the main rotor blade pitch angles differently to each other is the collective pitch lever. 555/3/1 d
_ 3 _ 9. The angle between the chord line of an airfoil and the direction of the airflow (relative airflow) is called the angle of attack. 10. An aircraft rolls about its lateral axis- (Answers on page 27) BASIC OPERATING PRINCIPLES If two or more airfoils (see Fig. 1) are fioined together, pivoted at the centre, held horizontal, and then spun around quickly, they will rise straight upwards because of the lift developed by the airfoils as they move through the air. This device FIG. l mentioned earlier. Should a gust of wind tilt it to one side while it is flying, then it will move in the direction of the tilt. All the time that the lift generated exceeds its weight, the top climbs, and when the lift is equal to the weight the top hovers, and when it becomes less, the top descends. The helicopter main rotor operates in a similar way to the flying top, except that it is power driven and its tilt is controlled by the pilot. Because the main rotor is power driven, a torque reaction equal and opposite to the torque turning the rotor is developed. (Newton's third law of motion.) If this torque reaction were allowed to act unhindered, then the fuselage of the helicopter would turn in the opposite direction to the main rotor. The c component that controls the effect of the torque reaction is usually a tail rotor, which is a vertical, side-mounted propeller ' WhOS@ blade angles can be moved from a positive pitch through 0° 555/3/1 is the Chinese flying top -