Qantas cancels order for 35 Dreamliners

Qantas has cancelled an order for 35 Boeing 787-9 aircraft to reduce capital expenditure.

Deliveries of 15 787-8s to Jetstar, its low-cost subsidiary, will continue as planned, adds Australia’s flag carrier.

The 787-8s will allow the transfer of Airbus A330s from Jetstar to Qantas Domestic, and the eventual retirement of Qantas’s Boeing 767 fleet.

The group will retain and bring forward 50 787-9 options and purchase rights by two years, with the aircraft available for delivery from 2016 if needed.

The Oneworld carrier says that the cancellation will help it to reduce capital expenditure commitments by $8.5 billion.

Total cash inflow from the restructuring will be $433 million, with $355 million coming in the 2012/13 financial year alone. These will result in a net impact on underlying profit before tax (PBT) and statutory PBT of approximately $140 million, to be recognised in the first half of 2012/13, says Qantas.

“Qantas continues to practice disciplined capital management and, in the context of returning Qantas International to profit, this is a prudent decision,” says chief executive Alan Joyce.

He adds that Qantas has “always maintained flexibility in its fleet plan and made changes when required”.

The carrier says that it has “substantially completed” its fleet renewal programme, with 114 new aircraft delivered over the past four years. The average scheduled passenger fleet age is 8.3 years, the lowest since privatisation in 1995.

Qantas has 12 A380s in service across its long-haul network and will complete the reconfiguration of nine Boeing 747-400s by late 2012. Boeing 737-800s will continue to enter the Qantas Domestic fleet, and A330s will be transferred from Jetstar as the 787-8s are delivered to the low-cost carrier.

Jetstar’s domestic and Asian fleet requirements will be met over the long term by the existing A320 order book and the arrival of the 787-8s, says Qantas.

Airbus 2050: the details are all in the future

Airbus has, for several years now, been promoting a vision of air travel in 2050. Starting with the basic structure, the “concept plane” was an attempt to imagine what might come to be if materials and aerodynamic ideas could be combined into a sort of “engineer’s dream”.

Airbus readily admitted that the result was “a package of technologies that are unlikely ever to coexist in such a manner”. The package was pretty – ultra-long and slim wings, semi-embedded engines, a U-shaped tail – but not especially radical as visions of the future go.

Far more thought-provoking fare came a year later. On the eve of the 2011 Paris air show, Airbus fleshed out some more radical notions of the passenger-aircraft interface, particularly inside the cabin.

 

Imagine, for example, an aircraft built of intelligent membranes that turn from opaque to transparent on command, to do away with windows and provide a panoramic view of the sky. Enhanced reality projection could add to the scene, or even turn it into images tailored to suit each passenger. Indeed, Airbus imagines palm-recognition check-in, so the aircraft would know each passenger intimately and, thanks to its smart materials and neural networks, be able to learn their preferences for, say, cabin lighting, or even seat shape.

Other ideas may be less esoteric. Bionic-inspired structures that mimic birds’ bones – strong where needed and light everywhere else – are already on the drawing board, and energy-harvesting techniques to capture passengers’ body heat to power onboard systems are already in use in the Stockholm metro.

Hydrogen fuel cells could provide emission-free onboard electric power while on the ground, while solar panels on the wings and fuselage could be another way to provide some onboard power.

Also probably much closer than 2050 are self-repairing materials that would help keep a cabin in as-new condition. Fully recyclable plant fibres could replace many non-renewable materials used today.

OPERATIONS

Now, with a more careful look at how savings – particularly of fuel – may be found in operations, Airbus has perhaps opened the most interesting aspect of what it hopes will be a wide-ranging debate over the future of air travel. As some of its latest ideas could conceivably be put into practice with little modification of the existing aircraft fleet, it may not be necessary to wait decades for their realisation.

Least controversial among what Airbus executive vice-president engineering Charles Champion describes as “disruptive ideas” needed to spur aviation towards its goal of halving carbon emissions by 2050 are two concepts for greater on-the-ground efficiency. One involves using navigation technology to optimise an aircraft’s actual landing position, so that an autonomous – and renewably powered – taxi tug could be waiting. The result could be that aircraft could switch off engines sooner but still be quickly pulled off runways, to optimise terminal space and remove runway and gate limitations.

Another is to create regional supplies of sustainable biofuels and energy sources ranging from hydrogen to solar electricity to power airports and aircraft.

Also not wildly futuristic are free-glide approaches and landings, which may be seen as an extension of the so-called 4D flights along optimum paths already being trialled and which are widely held to be possible if next-generation air traffic management systems are put in place. The purpose would be to remain in cruise altitude efficiency for longer, and reduce noise and emissions during approach by taking a steeper descent without engine thrust or air braking.

 

Airbus

Free-glide approaches would, Champion believes, also reduce landing speed – which would translate into shorter runways.

Also intriguing is Airbus’s notion of formation flying. The concept is not new, but, as Champion explains, it may not take a great leap to realisation. Champion estimates that by riding in another aircraft’s slipstream at a distance of about 1nm (1.85km), fuel burn could be reduced by 10-15% – about what might be expected by introducing the engines currently under development by Pratt & Whitney and CFM International to replace their popular V2500 and CFM56 narrowbody models around the middle of the decade.

He stresses that there is no question of attempting to maintain formations near airports; the idea only applies during flight in a “stable trajectory”; for example, over the ocean. And, he says, safety comes first, so for an aircraft to join a queue would always be a pilot-controlled manoeuvre.

Rather more daunting is an idea for assisted take-off. As Airbus presents it, aircraft would be propelled to take-off speed partly by their own engines and partly by a tractor (renewably powered, of course). The result would be quicker acceleration on shorter runways and steeper climb to cruise; aircraft could carry smaller engines, too, saving fuel all around.

What happens to these tractors when they reach the end of the runway at take-off speed, however, is one of those details that still needs to be worked out.

How can helicopter fly

GENERAL This is just the basic informations for the beginners which did not know any things about the helicopter or airplane before and wants to know some principles that why the helicopter can fly but not in deep details. For the people that want to know more than what I have in here, please go to the text book which have many professors wrote them or go to the specific helicopter manuals. The details about the helicopter has so much to put it all in the WEB. INTRODUCTION The wings of the airplane create a lift force when they move through the air. As we known,during flight, there are four forces acting on the helicopter or airplane and those are LIFT , DRAG , THRUST ,and WEIGHT .(please go back and see on What makes an airplane fly ? section).In order to make the wings to move through the air , of course, the plane itself has to move. A helicopter works by having its wings move through the air while the body stays still. The helicopter’s wings are called Main Rotor Blades. The shape and the angle of the blades move through the air will determine how much Lift force is created. After the helicopter lifted off the ground, the pilot can tilt the blades, causing the helicopter to tip forward or backward or sideward. NOMENCLATURE AND TECHNICAL TERM Although we will describe certain terms or parts of helicopter more in the next sections as we go along, but we should familier with all of these terms in order to understand the helicopter better. Bernoulli’principle :This principle states that as the air velocity increases, the pressure decreases; and as the velocity decreases, the pressure increases . Airfoil : is technically defined as any surface, such as an airplane aileron, elevator, rudder, wing, main rotor blades, or tail rotor blades designed to obtain reaction from the air through which it moves. Angle of Attack : is the acute angle measured between the chord of an airfoil and the relative wind. Angle of Incidence : is the acute angle between the wing’s chord line and the longitudinal axis of the airplane. (usually manufacturer had built the aircraft with the wing has some degrees to the horizontal plane or airplane longitudinal axis). Blades : The blades of the helicopter are airfoils with a very high aspect ratio ( length to chord ). The angle of incidence is adjusted by means of the control from pilots. The main rotor of the helicopter may have two, three,four , five or six blades, depending upon the design. The main rotor blades are hinged to the rotor head in such a manner that they have limited movement up and down and also they can change the pitch ( angle of incidence ). The controls for the main rotor are called Collective and Cyclic Controls. The tail rotor is small blades may have two or four blades and mounted on the tail of the helicopter,it rotates in the vertical plane. The tail rotor is controlled by the rudder pedals. Its pitch can be changed as required to turn the helicopter in the direction desired. Blade Root : The inner end of the blades where the rotors connect to the blade gripos. Blade Grips : Large attaching points where the rotor blade connects to the hub. Rotor Hub : Sit on top of the mast , and connects the rotor blades to the control tubes. Main Rotor Mast : Rotating shaft from the transmission which connects the main rotor blades to helicopter fuselage. Pitch Change Horn : to converts control tube movement to blade pitch. Control tube is a push-pull tubes that change the pitch of the rotor blades through the pitch changing horn. Swash Plate Assembly : The swash plate assembly consists of two primary elements through which the rotor mast passes. One element is a disc, linked to the cyclic pitch control. This disc is capable of tilting in any direction but does not rotate as the rotor rotates. This non-rotating disc, often refered to as the Stationary Star is attached by a bearing surface to a second disc, often refered to as the Rotating Star which turns with rotor and linked to the rotor blade pitch horns. Transmission : The transmission system transmits engine power to the main rotor, tail rotor, generator and other accessories. The engine is operated at a relative high speed while the main rotor turns at a much lower speed. This speed reduction is accomplished through reduction gears in the Transmission System Lift : is produced by a lower pressure created on the upper surface of an airplane’s wings compared to the pressure on the wing’s lower surfaces,causing the wing to be LIFTED upward. The special shape of the airplane wing (airfoil) is designed so that air flowing over it will have to travel a greater distance and faster resulting in a lower pressure area (see illustration) thus lifting the wing upward. Lift is that force which opposes the force of gravity (or weight). Lift depends upon (1) shape of the airfoil (2) the angle of attack (3) the area of the surface exposed to the airstream (4) the square of the air speed (5) the air density. Relative Wind : is the direction of the airflow with respect to an airfoil or to the rotor blades. Pitch Angle : The rotor blade pitch angle is the acute angle between the blade chord line and the rotor plane of rotation.( you may understand as the angle of incidence ) . This pitch angle can be varied by the pilot through the use of cockpit controls ( collective and cyclic pitch control ).

History of Flight I will bring you only some of History that I think it is useful for you to know about how the helicopter was developed. They were so many great people contributed to this technologies but some of them were succeed and some were not. We all thanks to those people which make today happen.   Igor Sikorsky (United States) It was during 1909 that Igor Sikorsky Build his first machine in Russia in common many earier designed. But this first Sikorsky helicopter never left the ground, and a second which followed in 1910 ,he did not succeeded at this time so, he stopped and turn to fixed wing aircraft until 1930 .   VS-300: In 1939, Sikorsky and a team of his engineers desinged the VS-300. The VS stood for VoughtSikorsky and the 300 indicated that it was Sikorsky’s third helicopter design.Vs300 had a75 hp Franklin 4cylinder engine. The basic structure was the heavygauge welded steel tubes. It had no covering at all and no instruments.It had three bladed main rotor and the anti-torque rotor at the rear. VoughtSikorsky VS-300   The R-4: In 1941, Sikorsky and Gluharaff designed the production model of VS300 and desinated VS316A . It was the bigger a bigger machine with an enclosed cabin and side by side seating and dual controls for two men crew 175 hp engine, a larger 36 ft (10.97 m.) rotor.The VS316A known by military designation XR-4 and YR4A. VS-316A   The R-5 and S-51: In 1943,Sikosky was working on all metal designated VS327 to meet requirement of USAAF known as XR5S and YR5A. It was better and bigger than R4. In 1946, the first civilian type helicopter,S51 (four seats) was the first helicopter to be licenced by the US Civil Aviation Administration for commercial operation. Sikorsky S-51   The S-55: In 1949, Sikorsky S-55 was located 600hp engine in the nose. For the first time, a helicopter was capable of lifting a heavy load up to ten soldiers,in addition to its two men crew. Sikorsky S-55   Focke Achgelis Fa61 (Germany)   Fa-61: Germany stepped to the front in helicopter development with the Focke Achgelis Fa-61, which it has two three-bladed rotor mounted on outriggers and power by a 160 hp radial engine. The Fa-61 had controllable cyclic pitch and set many of records . In 1938, Fa-61 made an altitude flight of 11,243 feet and cross-country of 143 miles.In this year, the german aviator Hanna Reitsch became the world’s first woman helicopter pilot by flying the Fa-61 in the Deustchland-halle in Berlin. Germany continued its helicopter development during world war two and was the first to place the helicopter,Flettner Kolibri, into mass production. Focke Achgelis Fa-61   Jaun de la Cierva (Spain) / Autogiro  Cierva C30A : An Autogiro, in 1923 , Juan de la Cierva , a young engineer made the first successful flight of an autogiro. An autogiro operates on a different principle than a helicopter.That was the rotor of autogiro was not driven by the engine but rotated itself as the aircraft was drawn along by its propeller. Autogiro used extreamely short take-off and landing but it could not move sideways or hover in still air like a helicopter. The Autogiro’s rotor is designed so that a blade set at a low positive angle of pitch will rotate automatically as long as an airstream is kept flowing through the rotor .However, the technology of the rotor head and the rotor blade developed for autogiro contributed importantly to the development of the successful of helicopter. Cierva C30A   Lawrence Bell (USA)   Bell Model 30 :Bell Aircraft Corporation was formed in 1935 but it was until 1943 that the first Bell Helicopter Model 30 was successful flown. Several version of model 30 were built . Model 47 , built in 1945 and was granted the world’s first commercial helicopter licence. The Bell 47 developed into the most successful light – utility helicopters ever. A total of morethan 6,000 variants were built until the production was stopped in 1973. Bell Model 30 Principle of Helicopter Flight ( page 1 ) GENERAL Helicopter, Lift is obtained by means of one or more power driven horizontal propellers which called Main Rotor. When the main rotor of helicopter turns it produces lift and reaction torque. Reaction torque tends to make helicopter spin. On most helicopters, a small rotor near the tail which called tail rotor compensates for this torque. On twin rotor helicopter the rotors rotate in opposite directions, their reactions cancel each other. Main Rotor The lifting force is produced by the main rotor . As they spin in the air and produced the lift. Each blade produces an equal share of the lifting force. The weight of a helicopter is divided evenly between the rotor blades on the main rotor system. If a helicopter weight 4000 lbs and it has two blades, then each blade must be able to support 2000 lbs.In addition to the static weight of helicopter ,each blade must be accept dynamic load as well . For example, if a helicopter pull up in a 1.5 g manouver (1.5 time the gravity force), then the effective weight of helicopter will be 1.5 time of static helicopter weight or 6000 lbs. due to gravitational pull. Tail Rotor The tail rotor is very important. If you spin a rotor with an engine, the rotor will rotate,but the engine and helicopter body will tend to rotate in opposite direction to the rotor. This is called Torque reaction. Newton’s third law of motion states , ” to every action there is an equal and opposite reaction” . The tail rotor is used to compensates for this torque and hold the helicopter straight. On twin-rotors helicopter , the rotors spin in opposite directions, so their reactions cancel each other. The tail rotor in normally linked to the main rotor via a system of driveshafts and gearboxes , that means if you turn the main rotor , the tail rotor is also turn.Most helicopter have a ratio of 3:1 to 6:1 . That is, if main rotor turn one rotation , the tail rotor will turn 3 revelutions (for 3:1)or 6 revolutions (for 6:1). In most helicopter the engine turns a shaft that connected to an input quill in the transmission gearbox. the main rotor mast out to the top and tail rotor drive shafts out to the tail from the tranmission gear box. Dissymmetry of Lift All rotor systems are subject to Dissymmetry of Lift in forward flight . At a hover , the lift is equal across the entire rotor disk . As the helicopter gain air speed , the advanceing blade develops greater lift because of the increased airspeed and the retreating blade will produce less lift , this will cause the helicopter to roll (for example: if rotor speed = 400 km/hr , helicopter move forward=100 km/hr then advancing blade will have speed=500 km/hr but the retreating blade will has moving speed of only 300 kr/hr ) . This has to be compensated for in some way . Blade Flapping Dissymmetry of lift is compensated for by Blade flapping. Because of the increased airspeed and lift on the advancing blade will cause the blade to flap up and decreasing the angle of attack . The decreased lift on the retreating blade will cause the blade to flap down and increasing the angle of attack . The combination of decreased angle of attack on the advancing blade and increased angle of attack on the retreating blade through blade flapping action tends to equalize the lift over the two halves of the rotor disc. Flight Direction Control ( page 1 ) GENERAL Helicopter, Lift is obtained by means of one or more power driven horizontal propellers which called Rotors. When the rotors of helicopter turns it produces lift and reaction torque, reaction torque which tends to make helicopter spin. on most helicopters a small rotor near the tail which called tail rotor compensates for this torque. On twin rotor helicopter the rotors rotate in opposite directions, their reactions cancel each other. The direction of helicopter is controlled by inclining the axis of the main rotor path in that direction. Function of Controls There are three major controls in the helicopter that the pilot must use during flight. They are : ( 1 ) Collective pitch control. ( 2 ) Anti Torque Pedals or Tail Rotor Control. ( 3 ) Cyclic Stick Control. Collective Control The collective pitch lever or stick is located by the left side of the pilot’s seat and is operated with the left hand. The collective is used to increase main rotor pitch at all points of the rotor blade rotation. It increases or decreases total rotor thrust. The collective lever is connected to the swash plate by a series of bush pull tubes. Raising the collective lever increases the pitch on the main rotor blade, lowering the collective lever decreases the main rotor blade pitch. The amount of movement of th elever determines the amount of blade pitch change. As the angle of attack increase, drag increases and Rotor RPM and Engine RPM tend to decrease . As the angle of attack decreases, drag decreases and the RPM tend to increase.Since it is essential that the RPM remain constant, there must be some means of making a proportionate change in power to compensate for the change in drag. This coordination of power change with blade pitch angle change is controlled through a collective pitch lever- trottle control cam linkage which automatically increases power when the collective pitch lever is raised and decreases power when the lever is lowered. The picture above is the typical collective lever but the detail of control may varies depend on each munufacturer .The main functions are still the same for all helicopters. Collective Lever is connected to the rotor system via push pull tubes. It also has droop com pensation devics which sense change in the collective pitch lever and increases or decreases fuel to the engine automatically somewhat in anticipated of a change in power required. This helps to minimize the RPM fluctuations during collective pitch change. Engine Control (Emergency) is the throttle twist grip. During emergency condition, between flight and flight idle positions. This is useful during any event which would cause engine or rotor RPM to go too high or while landing after a tail rotor failure. Idle Release Button, when the throttle is rolled from ” off ” to ” idle ” the idle release button snaps into a detent which prevents the throttle from being rolled back to ” off ” Starter Button : Pushing this button will cause the starter / generator to act as a starter motor ( Starter / Generator is a component that funtion in either mode as a starter or generator ) , turning over the engine. Landing Light Switch has a three position which are ” off ” , ” forward ” and “both ” . In forward , only the forward light is activated. In both, the forward and downward lights are activated . Power Trim Switch ,by holding it in ” increase ” or ” decrease ” the pilot can set the RPM that the pilot attempt to maintain. Function of Controls (Continue) Anti-Torque Pedals or Tail Rotor Control In accordance with Newton’s law of action and reaction, the helicopter fuselage tends to rotate in the direction opposite to the rotor blades . This effect is called torque . Torque must be counteracted and controlled to make flight is possible . Compensation for torque in a single main rotor helicopter is accomplished by means of a variable pitch antitorque rotor (tail rotor) located on the end of the tail boom extension at the rear of fuselage. Heading Control : In addition to counteracted torque, the tail rotor and its control linkage also permit control of the helicopter heading during flight . Application of more control than is necessary to counteract torque will cause the nose of helicopter to turn in the direction of pedal movement. In forward flight , the pedals are not used to control the heading of the helicopter (except during portions of crosswind takeoff and approach). They are used to compensate for torque to put the helicopter in longitudinal trim so that coordinated flight can be maintained. The thrust of the tail rotor is depend upon the pitch angle of the tail rotor blades. The tail rotor may have a positive pitch angle or it may have a negative pitch angle which to push the tail to the right or pull the tail to the left. With the right pedal pressed or moved forward of the neutral position will cause the tail rotor blades to change the pitch angle and the nose of helicopter will yaw to the right . With the left pedal pressed or moved forward of the neutral position will cause the tail rotor blades to change the pitch angle opposite to the right pedal and the nose of helicopter will yaw to the left. Function of Controls (Continue) Cyclic Control As mention earier , the total lift force is always perpendicular to the tip-path plane of the main rotor. When the tip path plane is tilt away from the horizontal, the lift -thrust force is divide into two components of forces that are, the horizontal acting force, thrust and the upward acting force, lift. The purpose of the cyclic pitch control is to tilt the tip path plane in the direction that horizontal movement is desired. The thrust component of force then pulls the helicopter in the direction of rotor tilt. The cyclic control changes the direction of this force,thus controlling the attitude and air speed of helicopter. The rotor disc tilts in the same direction of the cyclic stick was moved. If the cyclic stick is moved forward, the rotor disc tilt forward: if the cyclic is moved aft, the rotor disc tilt aft, and so on. The rotor disc will always tilt in the same direction that the cyclic stick is moved. The above picture is only typical for cyclic control stick which different manufacturer will have some detail different but the main fuction is the same. The radio switch is used for pilot to transmit radio by clicking the switch. The trim switch , pilot use this switch to neutralize stick force . Pilot can use the trim switch to put the stick to the right , left , forward or backward . This runs electric motor which will tension the spring which will tend to hold the stick. The cyclic will stay where it is even the pilot were let it go . This also release tension from pilot. The cargo release switch is the option switch, some manufacturer may have other function switch.

Aircraft Propellers

General Information

Thrust is the force that move the aircraft through the air.Thrust is generated by the propulsion system of the aircraft. There are different types of propulsion systems develop thrust in different ways, although it usually generated through some application of Newton’s Third Law. Propeller is one of the propulsion system. The purpose of the propeller is to move the aircraft through the air. The propeller consist of two or more blades connected together by a hub. The hub serves to attach the blades to the engine shaft. .

The blades are made in the shape of an airfoil like wing of an aircraft. When the engine rotates the propeller blades, the blades produce lift. This lift is called thrust and moves the aircraft forward. most aircraft have propellers that pull the aircraft through the air. These are called tractor propellers. Some aircraft have propellers that push the aircraft. These are called pusher propellers.

Description

Leading Edge of the airfoil is the cutting edge that slices into the air. As the leading edge cuts the air, air flows over the blade face and the cambe side.

Blade Face is the surface of the propeller blade that corresponds to the lower surface of an airfoil or flat side, we called Blade Face.

Blade Back / Thrust Face is the curved surface of the airfoil.

Blade Shank (Root) is the section of the blade nearest the hub.

Blade Tip is the outer end of the blade fartest from the hub.

Plane of Rotation is an imaginary plane perpendicular to the shaft. It is the plane that contains the circle in which the blades rotate.

Blade Angle is formed between the face of an element and the plane of rotation. The blade angle throughout the length of the blade is not the same. The reason for placing the blade element sections at different angles is because the various sections of the blade travel at different speed. Each element must be designed as part of the blade to operate at its own best angle of attack to create thrust when revolving at its best design speed

Blade Element are the airfoil sections joined side by side to form the blade airfoil. These elements are placed at different angles in rotation of the plane of rotation.

The reason for placing the blade element sections at different angles is because the various sections of the blade travel at different speeds. The inner part of the blade section travels slower than the outer part near the tip of the blade. If all the elements along a blade is at the same blade angle, the relative wind will not strike the elements at the same angle of attack. This is because of the different in velocity of the blade element due to distance from the center of rotation. The blade has a small twist (due to different angle in each section) in it for a very important reason. When the propeller is spinning round, each section of the blade travel at different speed, The twist in the peopeller blade means that each section advance forward at the same rate so stopping the propeller from bending. Thrust is produced by the propeller attached to the engine driveshaft. While the propeller is rotating in flight, each section of the blade has a motion that combines the forward motion of the aircraft with circular movement of the propeller. The slower the speed, the steeper the angle of attack must be to generate lift. Therefore, the shape of the propeller’s airfoil (cross section) must chang from the center to the tips. The changing shape of the airfoil (cross section) across the blade results in the twisting shape of the propeller.

Relative Wind is the air that strikes and pass over the airfoil as the airfoil is driven through the air.

Angle of Attack is the angle between the chord of the element and the relative wind. The best efficiency of the propeller is obtained at an angle of attack around 2 to 4 degrees.

Blade Path is the path of the direction of the blade element moves.

Pitch refers to the distance a spiral threaded object moves forward in one revolution. As a wood screw moves forward when turned in wood, same with the propeller move forward when turn in the air.

Geometric Pitch is the theoritical distance a propeller would advance in one revolution.

Effective Pitch is the actual distance a propeller advances in one revolution in the air. The effective pitch is always shorter than geometric pitch due to the air is a fluid and always slip.

Forces and stresses acting on a propeller in flight

The forces acting on a propeller in flight are : 1. Thrust is the air force on the propeller which is parallel to the directionof advance and induce bending stress in the propeller. 2. Centrifugal force is caused by rotation of the propeller and tends to throw the blade out from the center. 3. Torsion or Twisting forces in the blade itself, caused by the resultant of air forces which tend to twist the blades toward a lower blade angle.

The stress acting on a propeller in flight are : 1. Bending stresses are induced by the trust forces. These stresses tend to bend the blade forward as the airplane is moved through the air by the propeller. 2. Tensile stresses are caused by centrifugal force. 3. Torsion stresses are produced in rotating propeller blades by two twisting moments. one of these stresses is caused by the air reaction on the blades and is called the aerodynamic twisting moment. The another stress is caused by centrifugal force and is called the centrifugal twisting moment.

TYPE OF AIRCRAFT PROPELLERS

Type of propellers

In designing propellers, the maximum performance of the airplane for all condition of operation from takeoff, climb, cruising, and high speed. The propellers may be classified under eight general types as follows:

1. Fixed pitch: The propeller is made in one piece. Only one pitch setting is possible and is usually two blades propeller and is often made of wood or metal. Wooden Propellers : Wooden propellers were used almost exclusively on personal and business aircraft prior to World War II .A wood propeller is not cut from a solid block but is built up of a number of seperate layers of carefully selected .any types of wood have been used in making propellers, but the most satisfactory are yellow birch, sugar mable, black cherry, and black walnut. The use of lamination of wood will reduce the tendency for propeller to warp. For standard one-piece wood propellers, from five to nine seperate wood laminations about 3/4 in. thick are used. Metal Propellers : During 1940 , solid steel propellers were made for military use. Modern propellers are fabricated from high-strength , heat-treated,aluminum alloy by forging a single bar of aluminum alloy to the required shape. Metal propellers is now extensively used in the construction of propellers for all type of aircraft. The general appearance of the metal propeller is similar to the wood propeller, except that the sections are generally thinner.

2. Ground adjustable pitch: The pitch setting can be adjusted only with tools on the ground before the engine is running. This type of propellers usually has a split hub. The blade angle is specified by the aircraft specifications. The adjustable – pitch feature permits compensation for the location of the flying field at various altitudes and also for variations in the characteristics of airplanes using the same engine. Setting the blade angles by loosened the clamps and the blade is rotated to the desired angle and then tighten the clamps.

3. Two-position : A propeller which can have its pitch changed from one position to one other angle by the pilot while in flight.

4. Controllable pitch: The pilot can change the pitch of the propeller in flight or while operating the engine by mean of a pitch changing mechanism that may be operated by hydraulically.

5. Constant speed : The constant speed propeller utilizes a hydraulically or electrically operated pitch changing mechanism which is controlled by governor. The setting of the governor is adjusted by the pilot with the rpm lever in the cockpit. During operation, the constant speed propeller will automatically changs its blade angle to maintain a constant engine speed. If engine power is increase, the blade angle is increased to make the propeller absorb the additional power while the rpm remain constant. At the other position, if the engine power is decreased, the blade angle will decrease to make the blades take less bite of air to keep engine rpm remain constant. The pilot select the engine speed required for any particular type of operation.

6. Full Feathering : A constant speed propeller which has the ability to turn edge to the wind and thereby eliminate drag and windmilling in the event of engine failure. The term Feathering refers to the operation of rotating the blades of the propeller to the wind position for the purpose of stopping the rotation of the propeller to reduce drag. Therefore , a Feathered blade is in an approximate in-line-of-flight position , streamlined with the line of flight (turned the blades to a very high pitch). Feathering is necessary when the engine fails or when it is desirable to shutoff an engine in flight.

7. Reversing : A constant speed propeller which has the ability to assume a negative blade angle and produce a reversing thrust. When propellers are reversed, their blades are rotated below their positive angle , that is, through flat pitch, until a negative blade angle is obtained in order to produce a thrust acting in the opposite direction to the forward thrust . Reverse propeller thrust is used where a large aircraft is landed, in reducing the length of landing run.

8. Beta Control : A propeller which allows the manual repositioning of the propeller blade angle beyond the normal low pitch stop. Used most often in taxiing, where thrust is manually controlled by adjusting blade angle with the power lever.

Control and Operation   (page 1) Propeller Control       basic requirement: For flight operation, an engine is demanded to deliver power within a relatively narrow band of operating rotation speeds. During flight, the speed-sensitive governor of the propeller automatically controls the blade angle as required to maintain a constant r.p.m. of the engine. Three factors tend to vary the r.p.m. of the engine during operation. These factors are power, airspeed, and air density. If the r.p.m. is to maintain constant, the blade angle must vary directly with power, directly with airspeed, and inversely with air density. The speed-sensitive governor provides the means by which the propeller can adjust itself automatically to varying power and flight conditions while converting the power to thrust.       Fundamental Forces : Three fundamental forces are used to control blade angle . These forces are: 1. Centrifugal twisting moment, centrifugal force acting on a rotating blade which tends at all times to move the blade into low pitch. 2. Oil at engine pressure on the outboard piston side, which supplements the centrifugal twisting moment toward low pitch. 3. Propeller Governor oil on the inboard piston side, which balances the first two forces and move the blades toward high pitch Counterweight assembly (this is only for counterweight propeller) which attached to the blades , the centrifugal forces of the counterweight will move the blades to high pitch setting       Constant Speed, Counterweight Propellers The Counterweight type propeller may be used to operate either as a controllable or constant speed propeller. The hydraulic counterweight propeller consists of a hub assembly, blade assembly, cylinder assembly, and counterweight assembly. The counterweight assembly on the propeller is attached to the blades and moves with them. The centrifugal forces obtained from rotating counterweights move the blades to high angle setting. The centrifugal force of the counterweight assembly is depended on the rotational speed of the propellers r.p.m. The propeller blades have a definite range of angular motion by an adjusting for high and low angle on the counterweight brackets. Controllable : the operator will select either low blade angle or high blade angle by two-way valve which permits engine oil to flow into or drain from the propeller. Constant Speed : If an engine driven governor is used, the propeller will operate as a constant speed. The propeller and engine speed will be maintained constant at any r.p.m. setting within the operating range of the propeller.       Governor Operation (Constant speed with counterweight ) the Governor supplies and controls the flow of oil to and from the propeller. The engine driven governor receives oil from the engine lubricating system and boost its pressure to that required to operate the pitch-changing mechanism. It consists essentially of : 1. A gear pump to increase the pressure of the engine oil to the pressure required for propeller operation. 2. A relief valve system which regulates the operating pressure in the governor. 3. A pilot valve actuated by flyweights which control the flow of oil through the governor 4. The speeder spring provides a mean by which the initial load on the pilot valve can be changed through the rack and pulley arrangement which controlled by pilot. The governor maintains the required balance between all three control forces by metering to, or drain from, the inboard side of the propeller piston to maintain the propeller blade angle for constant speed operation. The governor operates by means of flyweights which control the position of a pilot valve. When the propeller r.p.m. is below that for which the governor is set through the speeder spring by pilot , the governor flyweight move inward due to less centrifugal force act on flyweight than compression of speeder spring. If the propeller r.p.m. is higher than setting , the flyweight will move outward due to flyweight has more centrifugal force than compression of speeder spring . During the flyweight moving inward or outward , the pilot valve will move and directs engine oil pressure to the propeller cylinder through the engine propeller shaft. Principles of Operation (Constant Speed with Counterweight Propellers) The changes in the blades angle of a typical constant speed with counterweight propellers are accomplished by the action of two forces, one is hydraulic and the other is mechanical. 1. The cylinder is moved by oil flowing into it and opposed by centrifugal force of counterweight. This action moves the counterweight and the blades to rotate toward the low angle positon. 2. When the oil allowed to drain from the cylinder , the centrifugal force of counterweights take effect and the blades are turned toward the high angle position. 3. The constant speed control of the propeller is an engine driven governor of the flyweight type. Governor Operation Condition On-Speed Condition The on-speed condition exists when the propeller operation speed are constant . In this condition, the force of the flyweight (5) at the governor just balances the speeder spring (3) force on the pilot valve (10) and shutoff completely the line (13) connecting to the propeller , thus preventing the flow of oil to or from the propeller.    The pressure oil from the pump is relieved through the relief valve (6). Because the propeller counterweight (15) force toward high pitch is balanced by the oil force from cylinder (14) is prevented from moving, and the propeller does not chang pitch Under-Speed Condition The under-speed condition is the result of change in engine r.p.m. or propeller r.p.m.which the r.p.m. is tend to lower than setting or governor control movement toward a high r.p.m. Since the force of the flyweight (5) is less than the speeder spring (3) force , the pilot valve (10) is forced down. Oil from the booster pump flows through the line (13) to the propeller. This forces the cylinder (14) move outward , and the blades (16) turn to lower pitch, less power is required to turn the propeller which inturn increase the engine r.p.m. As the speed is increased, the flyweight force is increased also and becomes equal to the speeder spring force. The pilot valve is move up, and the governor resumes its on-speed condition which keep the engine r.p.m. constant. Over-Speed Condition The over-speed condition which occurs when the aircraft altitude change or engine power is increased or engine r.p.m. is tend to increase and the governor control is moved towards a lower r.p.m. In this condition, the force of the flyweight (5) overcomes the speeder spring (3) force and raise the pilot valve (10) open the propeller line (13) to drain the oil from the cylinder (14). The counterweight (15) force in the propeller to turn the blades towards a higher pitch. With a higher pitch, more power is required to turn the propeller which inturn slow down the engine r.p.m. As the speed is reduced, the flyweight force is reduced also and becomes equal to the speeder spring force. The pilot valve is lowered, and the governor resumes its on-speed condition which keep the engine r.p.m. constant. Flight Operation This is just only guide line for understanding . The engine or aircraft manufacturers’ operating manual should be consulted for each particular aircrat.       Takeoff : Placing the governor control in the full forward position . This position is setting the propeller blades to low pitch angle Engine r.p.m. will increase until it reaches the takeoff r.p.m. for which the governor has been set. From this setting , the r.p.m. will be held constant by the governor, which means that full power is available during takeoff and climb. Cruising : Once the crusing r.p.m. has been set , it will be held constant by the governor. All changes in attitude of the aircraft, altitude, and the engine power can be made without affecting the r.p.m. as long as the blades do not contact the pitch limit stop. Power Descent : As the airspeed increase during descent, the governor will move the propeller blades to a higher pitch inorder to hold the r.p.m. at the desired value. Approach and Landing : Set the governor to its maximum cruising r.p.m. position during approach. During landing, the governor control should be set in the high r.p.m. position and this move the blades to full low pitch angle. Hydromatic Propellers Basic Operation Principles : The pitch changing mechanism of hydromatic propeller is a mechanical-hydraulic system in which hydraulic forces acting upon a piston are transformed into mechanical forces acting upon the blades. Piston movement causes rotation of cam which incorporates a bevel gear (Hamilton Standard Propeller) . The oil forces which act upon the piston are controled by the governor       Single Acting Propeller: The governor directs its pump output against the inboard side of piston only, A single acting propeller uses a single acting governor. This type of propeller makes use of three forces during constant speed operation , the blades centrifugal twisting moment and this force tends at all times to move the blades toward low pitch , oil at engine pressure applied against the outboard side of the propeller piston and this force to supplement the centrifugal twisting moment toward the low pitch during constant speed operation., and oil from governor pressure applied against the inboard side of the piston . The oil pressure from governor was boosted from the engine oil supply by governor pump and the force is controlled by metering the high pressure oil to or draining it from the inboard side of the propeller piston which balances centrifugal twisting moment and oil at the engine pressure.       Double Acting Propeller: The governor directs its output either side of the piston as the operating condition required. Double acting propeller uses double acting governor. This type of propeller , the governor pump output oil is directed by the governor to either side of the propeller piston.       Principle Operation of Double Acting : Overspeed Condition : When the engine speed increases above the r.p.m. for which the governor is set . Oil supply is boosted in pressure by thr engine driven propeller governor , is directed against the inboard side of the propeller piston. The piston and the attached rollers move outboard. As the piston moves outboard , cam and rollers move the propeller blades toward a higher angle , which inturn, decreases the engine r.p.m. Underspeed Condition : When the engine speed drops below the r.p.m. for which the governor is set. Force at flyweight is decrease and permit speeder spring to lower pilot valve, thereby open the oil passage allow the oil from inboard side of piston to drain through the governor. As the oil from inboard side is drained , engine oil from engine flows through the propeller shaft into the outboard piston end. With the aid of blade centrifugal twisting moment, The engine oil from outboard moves the piston inboard. The piston motion is transmitted through the cam and rollers . Thus, the blades move to lower angle The Feathering System Feathering : For some basic model consists of a feathering pump, reservoir, a feathering time-delay switch, and a propeller feathering light. The propeller is feathered by moving the control in the cockpit against the low speed stop. This causes the pilot vave lift rod in the governor to hold the pilot valve in the decrease r.p.m. position regardless of the action of the governor flyweights. This causes the propeller blades to rotate through high pitch to the feathering position.       Some model is initiated by depressing the feathering button. This action, auxiliary pump, feather solinoid, which positions the feathering valve to tranfer oil to feathering the propeller. When the propeller has been fully feathered, oil pressure will buildup and operate a pressure cutout switch which will cause the auxiliary pump stop. Feathering may be also be accomplished by pulling the engine emergency shutdown handle or switch to the shutdown position. Unfeathering : Some model is accomblished by holding the feathering buttn switch in the out position for about 2 second . This creates an artificial underspeed condition at the governor and causes high-pressure oil from the feathering pump to be directed to the rear of the propeller piston. As soon as the piston has moved inward a short distance, the blades will have sufficient angle to start rotation of the engine. When this occurs , the un-feathering switch can be released and the governor will resume control of the propeller.

What Makes An Airplane Fly

GENERAL

This is just the basic informations for the beginners which did not know any things about the aircraft or airplane before and wants to know some principles that why the airplane can fly but not in deep details. For the people that want to know more than what I have in here, please go to the text book which have many professors wrote them and the details about the airplane have so much to put it all in the WEB.

INTRODUCTION

It was , of couse, the birds who were responsible for the whole complicated story and business. A man with the brain of a scientist began to think seriouly about attainment of the dream. This was Leonado da Vinci (1452-1519), whose detail study of bird flight nevertheless led him to the erroneous conclusion that man’s muscular power, so superior to that of the birds, should enable him to fly in a properly constructed ornithopter,or flapping-wing aircraft.

In 1680, Giovanni Alphonso Borelli’s has a result of his detailed study of bird flight, man did not have the power output needed to lift himself and a machine into the air. This brought an end to practically all heavier-than-air experiments until nineteenth century.

On October 15, 1783, Jean-Francois had made a flight in a Mongolfier hot-air balloon tethered flight for 4 minutes 24 second. Lessthan two month later a hydrogen-filled balloon had completed a successful two-hours free flight.

German Otto Lilienthal(1848-1896), whose graceful and beautifully-constructed hang-gliders enable him to become the first man in the world to fly confidently and regularly, total more than 2000 flights.He did not develop control surfaces for his gliders, but rely on body movements to provide limited control in the three axes of pitch, yaw, and roll. He lost his life at age of 48 on 10 August 1896 due to one of his gliders stalled and crashed to the ground. The persons who pioneer of the gliders were Otto Lilienthal (German), Percy Pilcher (England) He also lost his life in a glider clashed three years after Lilienthal, and Octave Chanute (American)(1832-1910)

Wilbur (1867-1912) and Orville (1871-1948) Wright, had been interested in the possibility of mechanical flight in the early years. By 1900, they became freinds with Chanute . Chanute encouraged , providing information, and directly assisted the Wrights to achieve their goal of power flight later.First flight they flied the flyer was on 17 December 1903.This is generally accepted as the first man to accomplised the dream.Eventhrough there are some controversy over the first powered aircraft.

Alberto Santos-Dumont a little brazilian living in France. During 1906, with his No.14-bis which was power by a 50 horsepower Antoinette engine, he made a first flight of 60 meter at Bagattelle, Paris on 23 October 1906. Some people believed that Santos-Dumont really had made the first power flight in history.

NOMENCLATURE or TECHNICAL TERM

Although we will describe certain terms or parts of airplane more in the next sections as we go along, but we should familier with all of these terms in order to understand the airplane better.

Aerodynamics : Aero is derived from the Greek word meaning AIR, and Dynamics comes from the Greek word meaning Power, or branch of physics which considers bodies in motion and the forces that produce or change such motion. When Aero is combined with Dynamics ,we have Aerodynamics,Meaning ” The science relating to the effects produced by air or other gases in motion”.

Air Currents : are movement of the air with respect to the earth. If the air is rising from the earth , it is called a Vertical Current

Relative Motion : Motion is a movement.If an object changes it position,it is in motion. Relative Motion defined as an object which has moved or has changed its position with Respect to some other object. An Airplane must have Relative motion between Airplane and the Air in order to fly.The velocity of this motion is called the True Airspeed

Bernoulli’principle : This principle states that as the air velocity increases, the pressure decreases; and as the velocity decreases, the pressure increases

Airfoil : is technically defined as any surface, such as an airplane aileron, elevator, rudder, or wing, designed to obtain reaction from the air through which it moves.

Angle of Attack : is the acute angle measured between the chord of an airfoil and the relative wind.

Cockpit : is the pilot’s compartment which is seperated from the rest of the cabin.

Control Stick or Control Column : A vertical lever or column by mean of which the pilot operates the longitudinal and lateral control surfaces of the airplane. The elevator is operated by fore-and-aft movement of the stick or column, and ailerons are moved by sideways movement of the stick or turn the wheel to left or right.

Aileron : One of a pair of movable control surfaces attached to the trailing edge of each wing tip, the purpose of which is to control the airplane in roll by creating unequal or opposing lifting forces on the opposite sides of the airplane.

Elevator : A movable auxiliary airfoil or control surface designed to impress a pitching movement on the airplane, that is, to cause rotation about the lateral axis.

Flap : A hinged, pivoted, or sliding airfoil or plate, normally located at the trailing edge of a wing, extended or deflected to increase the lift and/or drag, generally used at takeoff and landing.

Rudder : A hinged or movable auxiliary airfoil used to impress a yawing moment on the aircraft.

Rudder Pedal : Either one of a pair of cockpit pedals for operating a rudder or other directional control device. The pedals are on the floor and feet operated.

Stabilizer : A fixed or adjustable airfoil or vane that provides stability for an aircraft.

HISTORY of FLIGHT Ornithopters (Flapping- wing) The beauty and freedom of birds has always drawn our admiration and envy. The freedom to move in any direction over all obstacles is a capability that all of us would enjoy. early attempts to defy gravity involved the invention of machines, such as Ornithopters. This type of flying machine utilizes the flapping of the wings in order to achieve flight. Needless, is to say that all attempts to fly using this type of machine failed. Machine lighter-than-air In the year between 1650 and 1900 , there was a second attempt at flying with a less sophisticated but more efficient generation of flying machines, the lighter-than-air craft. The idea of filling a closed container with a substance that normally rises through the atmosphere was known as early as the thirteen century. Over a five hundred year span, different substances came to be known as being lighter-than-air. The most common gas proposed was water vapor, helium and hydrogen. The first successful attempts at achiveing flight using his type of crafts were made by the Montgolfier brothers in France. Their most successful attempt was in 1783. The most successful builder of this type of lighter-than-air craft was Count Ferdinand von Zeppelin (picture above) . In the early 1930’s the German Graft Zeppelin machine was able to make a Trans-Atlantic flight to the United States. The large Hidenburg was equally successful until it was destroyed by fire while attempting a landing in 1937 at Lakehurst,New Jersey. Orville and Wilbur Wright In the early 1900s two American brothers, Orville and Wilbur Wright from Dayton, Ohio began to experiment with gliders. The gliders were built using data from Otto Lilienthal in Europe. Most of these flights turn out to be a failure. In 1901, they decided to gather their own wing data by conducting systematic experiment on different type of wing configurations. In 1902, Glider has wingtip to wingtip measurement of 32 ft. and wing width of 5 ft. This was the first aircraft with three-axis control. This mean that the aircraft could go up or down, left or right, and could also roll about its longitudinal axis. At Kitty Hawk, they perform over 800 flights, the early problem of aircraft were solved . The Wright brothers, now confident about their ability to flight, decided to turn their attention to power. In 1903, after redesigning the airframe of their 1902 glider, the Kitty Hawk Flyer was born. In December 17 , 1903 , with this aircraft, Orville and Wilbur Wright demanstrated the flight of self powered aircraft. Following the Wright Brothers success, the aeronautical activity took place basically everywhere in the world. Bleriot XI Monoplane The future potential of the airplane was realized when Louis Bleriot (France) flew his XI monoplane across the Einglish Channel in 1909. This was made Britain could no longer feel secure because England rely only on the royal navy. Henri Fabre Seaplane The first Seaplane was built and flown by Henri Fabre (France) in 1910 at Martigues, France. The great pioneer of marine flying was Glen Curtiss of the United States. In 1911 he fitted floats to his pusher biplanes and flow it off the water. First flight of a seaplane called a Hydravion was created by Frenchman Henri Fabre. Using a 50 horsepower Gnome rotary engine, Fabre flew 1650 feet on water (March 28, 1910). Vikers Gunbus: Until 1914 , As the war progressed, the manufacturers were pressed to equip airplanes with guns, bombs and torpedos. This Vicker Gunbus (England) had been accomplished by 1914. F.X. Trimotor: From the United States, Ford Trimotor is the world’s first airline services were in 1910. With the advances in aircraft designed brought about by war, the enclosed cabin airplane became the standard for commercial airline travel by the early 1920’s. As the time went by, the speed of airplanes began to increase. From the famous 12 mph top-speed of Wright Brithers Kitty Hawk Flyer , until in 1947, a test pilot named Chuck Yeager flied exceeded the speed of sound. From that point on a series of experimental supersonic aircraft took to the sky breaking speed record after speed record. Today we still can see some of supersonic aircrafts that were built in the 1960’s like Concorde(mach 2), TU-144 (mach 2.2), SR-71 Blackbird (mach 3). PRINCIPLES Forces Acting on An Airplane There are four forces acting on the airplane all the time during airplane is flying.The four forces are (1) Lift, (2) Gravity force or Weight, (3) Thrust, and (4) Drag. Lift and Drag are considered aerodynamics forces because they exist due to the movement of the Airplane through the Air. Lift: is produced by a lower pressure created on the upper surface of an airplane’s wings compared to the pressure on the wing’s lower surfaces,causing the wing to be LIFTED upward. The special shape of the airplane wing (airfoil) is designed so that air flowing over it will have to travel a greater distance and faster resulting in a lower pressure area (see illustration) thus lifting the wing upward. Lift is that force which opposes the force of gravity (or weight). Lift depends upon (1) shape of the airfoil (2) the angle of attack (3) the area of the surface exposed to the airstream (4) the square of the air speed (5) the air density. Weight: The weight acts vertically downward from the center of gravity (CG) of the airplane. Thrust: is defined as the forward direction pushing or pulling force developed by aircraft engine . This includes reciprocating engines , turbojet engines, turboprop engines. Drag: is the force which opposes the forward motion of airplane. specifically, drag is a retarding force acting upon a body in motion through a fluid, parallel to the direction of motion of a body. It is the friction of the air as it meets and passes over an airplane and its components. Drag is created by air impact force, skin friction, and displacement of the air. Aircraft Flight Control An airplane is equipped with certain fixed and movable surfaces or airfoil which provide for stability and control during flight. These are illustrated in the picture. Each of the named of the airfoil is designed to perform a specific function in the flight of the airplane. The fixed airfoils are the wings, the vertical stabilizer, and the horizontal stabilizer. The movable airfiols called control surfaces, are the ailerons, elevators, rudders and flaps.The ailerons, elevators, and rudders are used to “steer” the airplane in flight to make it go where the pilot wishes it to go. The flaps are normally used only during landings and extends some during takeoff. Aileron: may be defined as a movable control surface attached to the trailing edge of a wing to control an airplane in the roll, that is , rotation about the longitudinal axis. Elevator: is defined as a horizontal control surface, usually attached to the trailing edge of horizontal stabilizer of an airplane, designed to apply a pitching movement to the airplane. A pitching movement is a force tending to rotate the airplane about the lateral axis,that is nose up or nose down. Rudder: is a vertical control surface usually hinged to the tail post aft of the vertical stabilizer and designed to apply yawing movement to the airplane, that is to make it turn to the right or left about the vertical axis. Wing Flaps: are hinged or sliding surfaces mounted at the trailing edge of wings and designed to increase the camber of the wings. The effect is to increase the lift of the wings. FLIGHT DIRECTIONAL CONTROL THE AXES OF ROTATION An airplane has three axes of rotation, namely , the longitudinal axis, the vertical axis, and the lateral axis. see figure below and you will understand what we mean. The simplest way to understand the axes is to think of them as long rods passing through the aircraft where each will intersect the other two. At this point of intersection, called the center of gravity. The Axis that extends lengthwise (nose through tail) is call the longitudinal axis, and the rotation about this axis is called “Roll” The axis that extends crosswise (wing tip through wing tip) is called the lateral axis, and rotation about this axis is called “Pitch” The axis that passes vertically through the center of gravity (when the aircraft is in level flight ) is called the vertical axis, and rotation about this axis is called “Yaw” The Longitudinal Axis: The Axis Running from the nose to the tail of an aircraft is the longitudinal axis (see picture above). The movement around the longitudinal axis is called roll. The cause of movement or roll about the axis is the action of the ailerons. Ailerons are attached to the wing and control through the control column in a manner that ensures one aileron will deflect downward when the other is deflected upward. When an aileron is not in perfect alignment with the total wing, it changes the wing’s lift characteristics.To make a wing move upward, the aileron on that wing must move downward. The wing that has aileron downward produce more lift on that wing. the wing that has the aileron upward will reduce lift on that wing . This cause the aircraft to roll. The ailerons are attached to the cockpit control column by mechanical linkage. When the control wheel is turned to the right (or the stick is move to the right ), the aileron on the right wing is raised and the aileron on the left wing is lowered. This action increases the lift on the left wing and decreases the lift on the right wing, thus causing the aircraft to roll to the right. Moving the control wheel or stick to the left reverses this and causes the aircraft to roll to the left. See Roll Action Animation Click Here The Lateral Axis The lateral axis runs from wingtip to wingtip.The movement around the lateral axis is called pitch.What causes this pitching movement ?. It is the elevator which is attached to the horizontal stabilizer. The elevator can be deflected up or down as the pilot moves the control column (or stick) backward or foreward. Movement backward on the control column moves the elevator upward. (see picture above) The relative wind (RW) striking the top surface of the raised elevator pushes the tail downward. This motion is around the lateral axis, as the tail moves (pitches) downward, the nose moves (pitches) upward and the aircraft climbs. Movement forward on the control column moves the elevator downward . The relative wind (RW) striking the lower surface of the elevator causes the tail to pitch up and the nose of the aircraft downward causing the airplane to dives. See Pitch Action Animation Click Here The Vertical Axis: The third axis which passes through from the top of the aircraft to the bottom is called the vertical or yaw axis. The aircraft’s nose moves about this axis in a side-to-side direction. The airplane’s rudder, which is moved by pressing on the rudder pedals which are on the floor. The airplane’s rudder is responsible for movement about this axis.The rudder is a movable control surface attached to the vertical fin of the tail assembly. By pressing the proper rudder pedal, right pedal moves the rudder to the right, and left pedal moves the rudder to the left, when pilot press the left rudder pedal, that mean the pilot sets the rudder so that it defects the relative wind to the left. This then creates a force on the tail, causing it to move to the right and the nose of the aircraft to yaw to the left.

GLOBAL POSITIONING SYSTEM

GLOBAL POSITIONING SYSTEM

GPS (Global Positioning System) is the only system today able to show you where your exactly position on the earth at anytime and any weather condition. 24 satellites are all orbit around the earth at 11,000 nautical miles or approximately 20,200 kms. above the earth. The satellites are placed into six different orbital planes and 55 degree inclination. They are continuously monitored by ground stations located worldwide.

GPS ELEMENTS We can divide GPS system into three segments. SPACE SEGMENT USER SEGMENT CONTROL SEGMENT

SPACE SEGMENT The space segment comprises a network of satellites . The complete GPS space system includes 24 satellites, 11,000 nautical miles above the earth, take 12 hours each to go around the earth once or one orbit. They are orbit in six different planes and 55 degrees inclination. These positions of satellites, we can receive signals from six of them nearly of the time at any point on earth. Satellites are equipped with very precise clocks that keep accurate time to within three nanoseconds ( 0.000000003 of a second or 3e-9) This precision timing is important because the receiver must determine exactly how long it takes for signals to travel from each GPS satellite to receiver. Each satellite contains a supply of fuel and small servo engines so that it can be moved in orbit to correct for positioning errors. Each satellite contains four atomic clocks. These clocks are accurate to a nanosecond . Each satellite emits two seperate signals , one for military purposes and one for civilian use. SOME SPECIFICATION OF SATELLITE Weight     930 kg.(in orbit) Size     5.1 m. Travel Velocity      4 km/sec Transmit Signals      1575.42 MHz and 1227.60 MHz Receive at      1783.74 MHz Clocks      2 Cesium and 2 Rubidium Design life      7.5 year (later model BlockIIR 10 years)

USER SEGMENT As the pilot fly , the GPS receiver continuously caculates the current position and display the correct position / heading.The GPS unit listen to the satellite’s signal and measure the time between the satellites transmission and receipt of the signal. By the process of triangulation among the several satellites being received, the unit computes the location of the GPS receiver. GPS receiver has to see at least four satellites to compute a three dimensional position (it can compute position with only three satellites if know altitude). Not only latitude and Longitude , but altitude as well. There are numerous forms of display among the various manufacturer. No frequency tuning is required , as the frequency of the satellite transmissions are already known by the receiver.

CONTROL SEGMENT The control Segment of GPS consist of: Master Control Station ( one station ): The master control station is responsible for overall managment of the remote monitoring and transmission sites. As the center for support operations , It calculates any position or clock errors for each individual satellite from monitor stations and then order the appropriate corrective information back to that satellite. Monitor Stations ( four stations ): Each of monitor stations checks the exact altitude , position , speed , and overall of the orbiting of satellites. A station can track up to 11 satellites at a time. This check-up is performed twice a day by each station as the satellites go around the earth.

OPERATION The principle of GPS is the measurement of distance between the receiver and the satellites. The satellites also tell us exactly where they are in their orbit above the earth . The receiver knows our exact distance from satellite , knows the distance between satellites. GPS receivers have mathematical method by computer to compute exactly where the GPS receiver could be located.

AUTOMATIC DIRECTION FINDER

AUTOMATIC DIRECTION FINDER

ADF (Automatic Direction Finder) is the radio signals in the low to medium frequency band of 190 Khz. to 1750 Khz. It was widely used today. It has the major advantage over VOR navigation in the reception is not limited to line of sight distance. The ADF signals follow the curvature of the earth. The maximum of distance is depend on the power of the beacon. The ADF can receives on both AM radio station and NDB (Non-Directional Beacon). Commercial AM radio stations broadcast on 540 to 1620 Khz. Non-Directional Beacon operate in the frequency band of 190 to 535 Khz.

ADF COMPONENTS ADF Receiver : pilot can tune the station desired and to select the mode of operation. The signal is received, amplified, and converted to audible voice or morse code transmission and powers the bearing indicator. Control Box (Digital Readout Type) : Most modern aircraft has this type of control in the cockpit . In this equipment the frequency tuned is displayed as digital readout. ADF automatically determines bearing to selected station and it on the RMI. Antenna : The aircraft consist of two antennas. The two antennas are called LOOP antenna and SENSE antenna. The ADF receives signals on both loop and sense antennas. The loop antenna in common use today is a small flat antenna without moving parts. Within the antenna are several coils spaced at various angles. The loop antenna sense the direction of the station by the strength of the signal on each coil but cannot determine whether the bearing is TO or FROM the station. The sense antenna provides this latter information. Bearing Indicator : displays the bearing to station relative to the nose of the aircraft. Relative Bearing is the angle formed by the line drawn through the center line of the aircraft and a line drawn from the aircraft to the radio station. Magnetic Bearing is the angle formed by a line drawn from aircraft to the radio station and a line drawn from the aircraft to magnetic north (Bearing to station). Magnetic Bearing = Magnetic Heading + Relative Bearing.

TYPE OF ADF INDICATOR Four types of ADF indicators are in use today. In every case, the needle points to the navigation beacon.Those four types are: Fixed Compass Card : It is fixed to the face of instrument and cannot rotate. 0 degree is always straight up as the nose of aircraft. The relationship of the aircraft to the station is refered to as ” bearing to the station ” MB or aircraft to magnetic north. This type of indicator, pilot must calculate for the bearing by formular MB = RB + MH Rotatable Compass Card : The dial face of the instrument can be rotated by a knob. By rotating the card such that the Magnetic Heading (MH) of the aircraft is adjusted to be under the pointer at the top of the card. The bearing to station (MB) can be read directly from the compass card without calculation and make it easy for pilot. Today , they designed automatically rotate the compass card of the instrument to agree with the magnetic heading (MH) of the aircraft . Thus MB to station can be read at any time without manually rotating the compass card on the ADF face. Single-Needle Radio Magnetic Indicator : Radio Magnetic Indicator is an instrument that combines radio and magnetic information to provide continuous heading , bearing , and radial information. The face of the single needle RMI is similar to that of the rotatable card ADF. Dual-Needle Radio Magnetic Indicator : The dual needle RMI is similar to single needle RMI except that it has a second needle. The first needle indicated just like single needle. inthe picture , the yellow needle is a single which indicate the Magnetic Bearing to the NDB station . The second needle is the green needle in the picture. The second needle (green) is point to VOR station .The dual needle indicator is useful in locate the location of an aircraft.

OPERATION

ADF operate in the low and medium frequency bands. By tuning to NDB station or commercial AM radio stations. NDB frequency and identification information may be obtained from aeronautical charts and Airport Facility Directory. The ADF has automatic direction seeking qualities which result in the bearing indicator always pointing to the station to which it is tuned. The easiest and perhaps the most common method of using ADF , is to ” home ” to the station . Since the ADF pointer always points to the station , the pilot can simply head the airplane so that the pointer is on the 0 (zero) degree or nose position when using a fixed card ADF . The station will be directly ahead of the airplane. Since there is almost always some wind at altitude and you will be allowing for drif, meaning that your heading will be different from your track. Off track , if the aircraft is left of track, the head of the needle will point right of the nose. If the aircraft is right of track , the head of the needle will point left of the nose. For fixed compass card , if you are not fly Homing and you want to fly heading at some degrees. You must use the formular MB = MH + RB to find out what degree the ADF pointer should be on. Today , the fixed card indicator is very unsatisfactory for every day use which can still be found on aircraft panels but not many planes that pilot actually uses it due to it has easier type of indicator. For rotatable compass card, it was a big step over the fixed card indicator. The pilot can rotate the compass card with the heading knob to display the aircraft MH ” straight up ” . Then the ADF needle will directly indicate the magnetic bearing to the NDB station. For Single needle Radio Magnetic Indicator , the compasscard is a directional gyro and it rotates automatically as the aircraft turns and provide continuous heading . It is accurately indicates the magnetic heading and the magnetic bearing to the beacon. This instrument is a ” hands off ” instrument. For dual needle Radio Magnetic Indicator, it is give the pilot information the same as the single needle such as aircraft heading and magnetic bearing to the NDB . The seacond indicator will point to VOR station . This help pilot to check the location of the aircraft at that time .

VERY HIGH FREQUENCY OMNI-RANGE

VERY HIGH FREQUENCY OMNI-RANGE

VOR (VHF Omni-Range) is the basic Electronic navigation that in use today . This VHF Omni-Range navigation method relies on the ground based transmitters which emitted signals to VOR receiver. The VOR system operates in the VHF frequency band , from 108.0 to 117.95 MHz. The reception of VHF signals is a line of sight situation . You must be on the minimum altitude of 1000 feet (AGL) above ground level in order to pick up an Omni signals service range.

VOR Range

VOR Class= Low Altitude       1,000-18,000 feet     Range 40 nautical miles

VOR Altitude       1,000-14,500 feet     Range 40 nautical miles

VOR Altitude      14,500-60,000 feet     Range 100 nautical miles

VOR Altitude      18,000-45,000 feet     Range 130 nautical miles

OPERATION

The VOR facility at ground base transmits two signals at the same time. One signal is constant in all directions as a reference phase. Another signal, it is variable-phase signal and it rotates through 360 degrees, like the beam from the lighthouse. Both signals are in phase when the variable signal passes 360 degrees (reference to magnetic north) and they are 180 degrees out of phase when the rotating signal passes 180 degrees The aircraft equipment receives both signals. The receiver will calculate the difference between the two signals, and interprets the result as a radial from the station to pilots on the aircraft. RADIALS: The two signals from VOR transmitter generate 360 lines like spokes in a wheel . Each line is called a Radial . VOR navigation equipment on the airplane will determine which of those 360 radials the airplane is on.

VOR INDICATOR

A : Rotating Course Card is calibrated from 0 to 360 degrees, which indicates the VOR bearing chosen as the reference to fly by pilot. B : Omni Bearing Selector or OBS knob , used to manually rotate the course card to where the point to fly to. C : TO-FROM indicator . The triangle arrow will point UP when flying to the VOR station. The arrow will point DOWN when flying away from the VOR station. A red flag replaces these TO-FROM arrows when the VOR is beyond reception range or the station is out. D : Course Deviation Indicator (CDI). This needle moves left or right indicating the direction to turn the aircraft to return to course. DOT : The horizontal dots at center are represent the aircraft away from the course . Each dot represent 2 degrees deviate from desired course.

How It Works

The followings are just the typical, some aircraft may be vary in details . The pilot can set VOR receiver to selected ground station or another word is to select a radial to define a magnetic course toward or away from VOR station on receiver. The Radial of the VOR receiver is divided into 360 degrees, at the point 360 is representing Magnetic North . When we called out , we called in three digits such as 090 that means on the East and 270 means on the West . The proper time to tune navigation receivers is while the aircraft is on the ground because the pilot has to do the flight planned and known where to go. After takeoff, usually start from altutude of 1000 feet minimum above ground level, the VOR receiver will get signals from transmitter and the flag will show arrow FROM (left picture).

When the aircraft has gone half way or close to next VOR station and VOR receiver got that signals from next station . The arrow flag will change from FROM to TO arrow (from right picture) . At this time, pilot should select OBS to Radial of next VOR station. CDI on the indicator shown off center by four dots and that means eight degrees off the course, the pilot must correct the heading of aircraft.

If the aircraft out of transmitter range or VOR station not operates, the VOR receiver will show red flag or indication to tell pilot that don’t misunderstand because CDI needle will stay at center all the time.

AIRCRAFT NAVIGATION SYSTEM

NAVIGATION INTRODUCTION

Finding the way from one place to another is called NAVIGATION. Moving of an aircraft from one point to another is the most important part for any kind of mission. Plotting on the paper or on the map a course towards a specific area of the earth , in the passed, used to be a task assigned to a specialised member of the aircraft’s crew such a navigator. Such a task was quite complicated and not always accurate. Since it depended on the observation , using simple maps and geometrical instruments for calculations. Today, aerial navigation has become an art which nears to perfection. Both external Navaids (Navigational Aids) and on-board systems help navigate any aircraft over thousand of miles with such accuracy that could only be imagined a few decades ago.

The Method of Navigation There are three main methods of air navigation. There are: 1. Pilotage , 2. Dead Reckoning , 3. Radio. Pilotage or Piloting is the most common method of air navigation. This method, the pilot keeps on course by following a series of landmarks on the ground. Usually before take-off, pilot will making pre-flight planning , the pilot will draws a line on the aeronautical map to indicate the desired course. Pilot will nots various landmarks , such as highways , railroad tracks, rivers , bridges . As the pilot flies over each of landmark , pilot will checks it off on the chart or map. If the plane does not pass directly over thelandmark , the pilot will know that he has to correct the course. Dead Reckoning is the primary navigation method used in the early days of flying. It is the method on which Lindberg relied on his first trans-Atlantic flight. A pilot used this method when flying over large bodies of water, forest, deserts. It demands more skill and experience than pilotage does. It is based on time, distance, and direction only. The pilot must know the distance from one point to the next, the magnetic heading to be flown. Pilot works on the pre-flight plan chart , pilot plan a route in advance. Pilot calculate the time to know exactly to reach the distination while flying at constant speed. In the air, the pilot uses compass to keep the plane heading in the right direction. Dead reckoning is not always a successful method of navigation because of changing wind direction. It is the fundamental of VFR flight. Radio Navigation is used by almost all pilots. Pilots can find out from an aeronautical chart what radio station they should tune to in a particular area. They can then tune their radio navigation equipment to a signal from this station. A needle on the navigation equipment tells the pilot where they are flying to or from station, on course or not . see sample of aeronautical chart , preflight plan chart : click here

Pilots have various navigation aids that help them takeoff,fly, and land safely. One of the most important aids is a series of air route traffic control , operated throughout the world. Most of the traffic control uses a radar screen to make sure all the planes in its vicinity are flying in their assigned airways. Airliners carry a special type of radar receiver and transmitter called a transponder. It receives a radar signal from control center and immediately bounces it back. When the signal got to the ground, it makes the plane show up on the radar screen. Pilots have special methods for navigating across oceans. Three commonly used methods are: 1. Inertial GuidanceThis system has computer and other special devices that tell pilots where are the plane located. 2.LORAN Long Range Navigation The plane has equipment for receiving special radio signals sent out continuous from transmitter stations. The signals will indicate the plane location 3.GPS Global Positioning System. is the only system today able to show your exact position on the earth any time, anywhere, and any weather. The system receiver on the aircraft will receives the signals from sattelites around the globe.

TERMINOLOGY

ADF Automatic Direction Finder. An aircraft radio navigation which senses and indicates the direction to a Low/Medium Frequency non-directional radio beacon (NDB) ground transmitter.

DME Distance Measuring Equipment. Ground and aircraft equipment which provide distance information and primary serve operational needs of en-route or terminal area navigation.

EAT Estimated Approach Time

EFIS Electronic Flight Instrument System , in which multi-function CRT displays replace traditional instruments for providing flight, navigation and aircraft system information, forming a so-called ” glass cockpit “.

ETA Estimated Time of Arrival

GPS Global Positioning System . A navigation system based on the transmission of signals from satellites provided and maintained by the United States of America and available to civil aviation users.

HDG Heading. The direction in which an aircraft’s nose points in flight in the horizontal plane, expressed in compass degrees (eg. 000 or 360 is North, 090 is East)

HSI Horizontal Situation Indicator. A cockpit navigation display, usually part of a flight-director system, which combines navigation and heading.

IFR Instrument Flight Rule . prescribed for the operation of aircraft in instrument meteorological condition.

ILS Instrument Landing System . consists of the localizer, the glideslope and marker radio beacons (outer, middle, inner). It provides horizontal and vertical guidance for the approach.

INS Inertial Navigation System. It uses gyroscopes and other electronic tracking systems to detect acceleration and deceleration, and computes an aircraft’s position in latitude and longitude. Its accuracy, however, declines on long flights. Also called IRS, or Inertial Reference System.

KNOT (kt) Standard Unit of speed in aviation and marine transportation, equivalent to one nautical mile per hour. One knot is equal to 1.1515 mph., and one nautical mile equals to 6,080 feet or 1.1515 miles. One knot is equal to one nautical mile per one hour.

LORAN C Long Range Navigation is a Long-Range low frequency Radio Navigation. Its range is about 1,200 nm by day to 2,300 nm. by night.

MAGNETIC COURSE Horizontal direction, measured in degrees clockwise from the magnetic north.

MACH NUMBER Ratio of true airspeed to the speed of sound. Mach 1 is the speed of sound at sea level. Its values is approximately 760 mph.

NDB Non-Directional Beacon. A medium frequency navigational aid which transmits non-directional signals , superimposed with a Morse code identifier and received by an aircraft’s ADF.

RMI Radio Magnetic Indicator. A navigation aid which combines DI ,VOR and /or ADF display and will indicate bearings to stations, together with aircraft heading.

RNAV Area Navigation. A system of radio navigation which permits direct point-to-point off-airways navigation by means of an on-board computer creating phantom VOR/DME transmitters termed waypoints.

TACAN TACtical Air Navigation. Combines VOR and DME and used by military aircraft only.System which uses UHF frequencies , providing information about the bearing and distance from the ground station we have tuned into.

TCAS Traffic Alert and Collision Avoidance System. Radar based airborne collision avoidance system operating independently of ground-based equipment. TCAS-I generates traffic advisories only. TCAS-II provides advisories and collision avoidance instructions in the vertical plane.

TRANSPONDER Airborne receiver / transmitter which receives the interrogation signal from the ground and automatically replies according to mode and code selected. Mode A and B wre used for identification, using a four digit number allocated by air traffic control. Mode C gives automatic altitude readout from an encoding altimeter.

VFR Visual Flight Rules. Rules applicable to flights in visual meteorological conditions.

VHF Very High Frequency. Radio frequency in the 30-300 Mhz band, used for most civil air to ground communication.

VOR Very High Frequency Omnidirectional Range. A radio navigation aid operating in the 108-118 Mhz band. A VOR groun station transmits a two- phase directional signal through 360 degrees. The aircraft’s VOR receiver enables a pilot to identify his radial or bearing From/To the ground station . VOR is the most commonly used radio navigation aid in private flying.

VORTAC A special VOR which combines VOR and DME for civil and military used . System provides information about the bearing and distance from the ground station we have tuned into.

AIRCRAFT GAS TURBINE ENGINES

ENGINE TYPES and APPLICATIONS

Introduction

Most of modern passenger and military aircraft are powered by gas turbine engines, which are also called jet engines. There are several types of jet engines, but all jet engines have some parts in common . Aircraft gas turbine engines can be classified according to (1) the type of compressor used and (2) power usage produces by the engine. Compressor types are as follows: 1. Centrifugal flow 2. Axial flow 3. Centrifugal-Axial flow. Power usage produced are as follows: 1. Turbojet engines 2. Turbofan engines. 3. Turboshaft engines.

Centrifugal Compressor Engines Centrifugal flow engines are compress the air by accelerating air outward perpendicular to the longitudinal axis of the machine. Centrifugal compressor engines are divided into Single-Stage and Two-Stage compressor. The amount of thrust is limited because the maximum compression ratio.

Principal Adventages of Centrifugal Compressor 1. Light Weight 2. Simplicity 3. Low cost.

Axial Flow Compressor Engines Axial flow compressor engines may incorporate one , two , or three spools (Spool is defined as a group of compressor stages rotating at the same speed) . Two spool engine , the two rotors operate independently of one another. The turbine assembly for the low pressure compressor is the rear turbine unit . This set of turbines is connected to the forward , low pressure compressor by a shaft that passes through the hollow center of the high pressure compressor and turbine drive shaft.

Advantages and Disadvantages Advantages: Most of the larger turbine engines use this type of compressor because of its ability to handle large volumes of airflow and high pressure ratio. Disadvantages: More susceptable to foreign object damage , Expensive to manufacture , and It is very heavy in comparision to the centrifugal compressor with the same compression ratio.

Axial-Centrifugal Compressor Engine Centrifugal compressor engine were used in many early jet engines , the efficiency level of single stage centrifugal compressor is relatively low . The multi-stage compressors are some what better , but still do not match with axial flow compressors. Some small modern turbo-prop and turbo-shaft engines achieve good results by using a combination axial flow and centrifugal compressor such as PT6 Pratt and Whitney of canada which very popular in the market today and T53 Lycoming engine.

Characteristics and Applications

The turbojet engine : Turbojet engine derives its thrust by highly accelerating a mass of air , all of which goes through the engine. Since a high ” jet ” velocity is required to obtain an acceptable of thrust, the turbine of turbo jet is designed to extract only enough power from the hot gas stream to drive the compressor and accessories . All of the propulsive force (100% of thrust ) produced by a jet engine derived from exhaust gas.

The turboprop engine : Turboprop engine derives its propulsion by the conversion of the majority of gas stream energy into mechanical power to drive the compressor , accessories , and the propeller load. The shaft on which the turbine is mounted drives the propeller through the propeller reduction gear system . Approximately 90% of thrust comes from propeller and about only 10% comes from exhaust gas. The turbofan engine : Turbofan engine has a duct enclosed fan mounted at the front of the engine and driven either mechanically at the same speed as the compressor , or by an independent turbine located to the rear of the compressor drive turbine . The fan air can exit seperately from the primary engine air , or it can be ducted back to mix with the primary’s air at the rear . Approximately morethan 75% of thrust comes from fan and less than 25% comes from exhaust gas.

The turboshaft engine : Turboshaft engine derives its propulsion by the conversion of the majority of gas stream energy into mechanical power to drive the compressor , accessories , just like the turboprop engine but The shaft on which the turbine is mounted drives something other than an aircraft propeller such as the rotor of a helicopter through the reduction gearbox . The engine is called turboshaft.