UNIT-1 HISTORY OF FLIGHT

UNIT-IIBASICS OF FLIGHT MECHANICSAirfoilsAn airfoils shape is defined by several parameters, which are shown in the figurebelow.Airfoil DefinitionsChord Line: Straight line drawn from the leading edge to the trailing edgeChord Length (c): Length of the chord lineMean Camber Line: Curved line from the leading edge to the trailing edge, whichis equidistant between the upper and lower surfaces of the airfoilMaximum (or Just) Camber: Maximum distance between the chord line and themean camber line.Maximum Thickness: Maximum distance between the upper and lower surfaces ofthe airfoil normal to the chord line.Span: Width of the airfoil.Angle of Attack: Angle between the chord line and the streamwise flow direction.Zero Lift Angle of Attack: Angle of Attack that will produce no lift. For oursymmetric wedge this would be an angle of attack of zero.Stall Angle of Attack: Angle of attack at which there is maximum lift (or liftcoefficient)Symmetric or Uncambered Airfoil: Upper and lower surfaces are mirror images,which leads to the mean camber line to be coincident with the chord line. Asymmetric airfoil will also have a just camber of zero.Cambered Airfoil: An asymmetric airfoil for which the mean camber line will beabove the chord line.Pitching Moment: Torque or moment created on the wing due to net lift and dragforces. Tends to rotate the leading edge either up or down.Uncambered AirfoilCambered AirfoilME 440 Aerospace Engineering Fundamentals Fall 20063Pitching Moment Coefficient:V Sc21mc2mwherem: pitching moment (will depend on the moment reference center)c: chord lengthCenter of Pressure: The moment reference center for which the moment is zero.Depends on the angle of attack.Aerodynamic Center: The moment reference center for which the moment doesnot vary with angle of attack.NACA ClassificationAirfoils have been classified by the National Advisory Committee for Aeronautics(NACA), the forerunner of NASA, and have been cataloged using a four digitcode. Hence a specific airfoil can be identified by NACA WXYZ whereW: maximum camber as % of the chord lengthX: Location of the maximum camber form the leading edge along the chordline in tenths of chord lengthY&Z: Maximum thickness in % of the chord length

UNIT-IIIAIRCRAFT CONFIGURATIONS

Different types of flight vehicles:Classification of aircraft:1.CLASSIFICATION BY CONFIGURATION POSITION OF THE WING LOW WING MID WING HIGH WING NUMBER OF WINGS MONO PLANE BI PLANE TRI PLANE SHAPE OF THE WINGS DELTA WING DIAMOND WING SWEPT WING GULL SHAPED WING POSITION OF THE WINGS CONVENTIONAL WING NO TAIL OR TAILESS HORIZONTAL TAIL LOCATED AOVE THE VERTICAL TAIL CANARD TYPE LOCATION AND TYPE OF LANDING GEAR RETRACTABLE NON RETRACTABLE TAIL WHEEL NOSE WHEEL CLASSIFICATION BY POWER PLANTS POWER PLANT TYPES PISTON ENGINE TURBO PROP TURBO SHAFT TURBO JET TURBO FAN ROCKET NUMBER OF ENGINES SINGLE ENGINE TWO ENGINE MULTI ENGINE LOCATION OF THE ENGINES NOSE FUSELAGE JET ENGINE SUBMERGED IN WING PYLON MOUNTING TYPES OF FUSELAGE ROUND SQUARE OVAL 5.CLASSIFICATION BY PURPOSE A.CIVIL B.CARGO C.MILITARY I.BOMBERS II.FIGHTERS III.INTERCEPTORS

Components of an Airplane and their Functions:An airplane contains the following important component sections:1. Fuselage2. Wings3. Empennage4. Landing gear5. Propulsion systemThe following figures show the isometric and extended view of basic components of an airplane.

1. Fuselage:Fuselage is the main body of an airplane which contains cabin /cockpit which provides space for crew members and flight controls for aircraft. Fuselage also provides space for passengers and payloads. It gives attachment points for some other aircraft components like wing. There are three kinds of fuselage structure. They are:1. Truss structure,2. Monocoque structure and3. Semi monocoque structure.

2. Wings:The wings are lifting devices in which series of airfoils are attached. It is placed in each side of the fuselage and they are the main lifting surfaces that support the airplane in flight. The cross- section of the wing is called as airfoil. There are numerous wing designs, sizes, and shapes used by the various manufacturers. Each fulfills a certain need with respect to the expected performance for the particular airplane. Wings may be attached at the top, middle, or lower portion of the fuselage. These designs are referred to as high-, mid-, and low-wing, respectively. The number of wings can also vary. Airplanes with a single set of wings are referred to as monoplanes, while those with two sets are called biplanes.Monoplane: An airplane that has only one main lifting surface or wing, usually divided into two parts by the fuselage.Biplane: An airplane that has two main airfoil surfaces or wings on each side of the fuselage, one placed above the other.3. Empennage:The correct name for the tail section of an airplane is empennage. The section of the airplane that includes the entire tail group, consisting of fixed surfaces such as horizontal stabilizer and vertical stabilizer and the movable surfaces such as rudder, elevator and one or more trim tabs. A second type of empennage design does not require an elevator. Instead, it incorporates a one-piece horizontal stabilizer that pivots from a central hinge point. This type of design is called a stabilator.4. Landing gear:The landing gear is the principle support of the airplane when parked, taxiing, taking off, or when landing. The most common type of landing gear consists of wheels, but airplanes can also be equipped with floats for water operations, or skis for landing on snow. The landing gear consists of three wheelstwo main wheels and a third wheel positioned either at the front or rear of the airplane. Landing gear employing a rear mounted wheel is called conventional landing gear. Airplanes with conventional landing gear are sometimes referred to as tail wheel airplanes. When the third wheel is located on the nose, it is called a nose wheel, and the design is referred to as a tricycle gear. A steerable nose wheel or tail wheel permits the airplane to be controlled throughout all operations while on the ground.5. Propulsion system:The powerplant usually includes both the engine and the propeller or simply the engine (Turbojet, ramjet and scramjet). The primary function of the engine is to provide the power to turn the propeller. It also generates electrical power, provides a vacuum source for some flight instruments, and in most single-engine airplanes, provides a source of heat for the pilot and passengers. The engine is covered by a cowling, or in the case of some airplanes, surrounded by a nacelle. The purpose of the cowling or nacelle is to streamline the flow of air around the engine and to help cool the engine by ducting air around the cylinders. The propeller, mounted on the front of the engine, translates the rotating force of the engine into a forward - acting force called thrust that helps move the airplane through the air.

Nacelle: A streamlined enclosure on an aircraft in which an engine is mounted. On multiengine propeller-driven airplanes, the nacelle is normally mounted on the leading edge of the wing.

CONVENTIONAL CONTROLWhenever an airplane changes its flight altitude or position in flight, it rotates about one or more of three axes, which are imaginary lines that pass through the airplanes centre of gravity. The three axes are as follows:1. Roll axis or longitudinal axis,2. Pitch axis or lateral axis and 3. Yaw axis or vertical axis.The axis system has been given below:

An airplane moves in three dimensions called 1. Roll, 2. Pitch and 3. Yaw. Roll:Roll is rotation about the longitudinal axis that goes down the center of the fuselage. The ailerons control rotation about the roll axis. Pitch: Pitch is rotation about the lateral axis of rotation, which is an axis parallel to the long dimension of the wings. The elevators control the pitch of the airplane. By controlling the pitch of the airplane, the elevators also control the angle of attack of the wing. To increase the angle of attack, the entire airplane is rotated up.Yaw: Yaw, which is controlled by the rudder, is rotation about the vertical axis, which is a line passing vertically through the center of the wing. It is important to note that all three axes go through the center of gravity (often abbreviated c.g.) of the airplane. The center of gravity is the balance point of the airplane. Or, equivalently, all of the weight of the airplane can be considered to be at that one point.CONTROL SURFACESThe purpose of flight control is to enable the aircraft to be rotated about its three axes. Aircraft flight control systems are classified as primary and secondary. The primary control systems consist of those that are required to safely control an airplane during flight. These include the ailerons, elevator (or stabilator), and rudder. Secondary control systems improve the performance characteristics of the airplane, or relieve the pilot of excessive control forces. Examples of secondary control systems are wing flaps and trim systems. Primary Control Surfaces:Ailerons:Ailerons control roll about the longitudinal axis. The ailerons are attached to the outboard trailing edge of each wing and move in the opposite direction from each other. Ailerons are connected by cables, bellcranks, pulleys or push-pull tubes to each other and to the control wheel. Moving the control wheel to the right causes the right aileron to deflect upward and the left aileron to deflect downward. The upward deflection of the right aileron decreases the camber resulting in decreased lift on the right wing. The corresponding downward deflection of the left aileron increases the camber resulting in increased lift on the left wing. Thus, the increased lift on the left wing and the decreased lift on the right wing cause the airplane to roll to the right.Elevator:The elevator controls pitch about the lateral axis. Like the ailerons on small airplanes, the elevator is connected to the control column in the cockpit by a series of mechanical linkages. Aft movement of the control column deflects the trailing edge of the elevator surface up. This is usually referred to as up elevator. Moving the control column forward has the opposite effect. When the elevator is deflected downwards, elevator camber increases, creating more lift (less tail-down force) on the horizontal stabilizer/elevator. This moves the tail upward and pitches the nose down. Similarly when the elevator is deflected upwards, the elevator camber decreases, creating less lift on horizontal stabilizer and thus the pitches the nose of the airplane up.Rudder:The Rudder controls movement of the airplane about its vertical axis. This motion is called yaw. Like the other primary control surfaces, the rudder is a movable surface hinged to a fixed surface, in this case, to the vertical stabilizer, or fin. Moving the left or right rudder pedal controls the rudder. When the rudder is deflected into the airflow, a horizontal force is exerted in the opposite direction. By pushing the left pedal, the rudder moves left. This alters the airflow around the vertical stabilizer/rudder, and creates a sideward lift that moves the tail to the right and yaws the nose of the airplane to the left. Rudder deflections increases with speed, so large deflections at low speeds and small deflections at high speeds may be required to provide the desired reaction. In propeller-driven aircraft, any slipstream flowing over the rudder increases its effectiveness.

SECONDARY CONTROL SURFACESThe secondary control surfaces are as follows: Flaps, Leading edge devices, Spoilers, Speed brakes and Trim system: Trim tabs, Balance tabs, Antiservo tabs, Spring tabs and Ground adjustable tabs.