Early History of FlightPart 1: Humans try to fly like birds

Around 400 BC - Flight in China

The discovery of the kite that could fly in the air by the Chinese started humans thinking about flying. Kites were used by the Chinese in religious ceremonies. They built many colorful kites for fun, also. More sophisticated kites were used to test weather conditions. Kites have been important to the invention of flight as they were the forerunner to balloons and gliders.

Humans Try to Fly like Birds

For many centuries, humans have tried to fly just like the birds and have studied the flight of birds. Wings made of feathers or light weight woods have been attached to arms to test their ability to fly. The results were often disastrous as the muscles of the human arms are not like a birds and cannot move with the strength of a bird.

Hero and the Aeolipile

The ancient Greek engineer, Hero of Alexandria, worked with air pressure and steam to create sources of power. One experiment that he developed was the aeolipile which used jets of steam to create rotary motion.

Hero mounted a sphere on top of a water kettle. A fire below the kettle turned the water into steam, and the gas traveled through pipes to the sphere. Two L-shaped tubes on opposite sides of the sphere allowed the gas to escape, which gave a thrust to the sphere that caused it to rotate. The importance of the aeolipile is that it marks the start of engine invention - engine created movement will later prove essential in the history of flight. 

1485 Leonardo da Vinci - The Ornithopter and the Study of Flight.

Leonardo da Vinci made the first real studies of flight in the 1480's. He had over 100 drawings that illustrated his theories on bird and mechanical flight. The drawings illustrated the wings and tails of birds, ideas for man carrying machines, and devices for the testing of wings. 

The Ornithopter flying machine was never actually created. It was a design that Leonardo da Vinci created to show how man could fly. The modern day helicopter is based on this

concept. Leonardo da Vinci's notebooks on flight were reexamined in the 19th century by aviation pioneers.

1783 - Joseph and Jacques Montgolfier - The Flight of the First Hot Air Balloon

The brothers, Joseph Michel and Jacques Etienne Montgolfier, were inventors of the first hot air balloon. They used the smoke from a fire to blow hot air into a silk bag. The silk bag was attached to a basket. The hot air then rose and allowed the balloon to be lighter-than-air.

In 1783, the first passengers in the colorful balloon were a sheep, rooster and duck. It climbed to a height of about 6,000 feet and traveled more than one mile.

After this first success, the brothers began to send men up in hot air balloons. The first manned flight was on November 21, 1783, the passengers were Jean-Francois Pilatre de Rozier and Francois Laurent.

1799-1850's - George Cayley - Gliders

Sir George Cayley is considered the father of aerodynamics. Cayley experimented with wing design, distinguished between lift and drag, formulated the concepts of vertical tail surfaces, steering rudders, rear elevators, and air screws. George Cayley worked to discover a way that man could fly. Cayley designed many different versions of gliders that used the movements of the body to control. A young boy, whose name is not known, was the first to fly one of Cayley's gliders, the first glider capable of carrying a human.

For over 50 years, George Cayley made improvements to his gliders. Cayley changed the shape of the wings so that the air would flow over the wings correctly. Cayley designed a tail for the gliders to help with the stability. He tried a biplane design to add strength to the glider. George Cayley also recognized that there would be a need for machine power if the flight was to be in the air for a long time.

George Cayley wrote "On Ariel Navigation" that showed that a fixed wing aircraft with a power system for propulsion, and a tail to assist in the control of the airplane, would be the best way to allow man to fly.

Part 2: 19th And 20th Century Flight Efforts

1891 Otto Lilienthal

German engineer, Otto Lilienthal, studied aerodynamics and worked to design a glider that would fly. Otto Lilienthal was the first person to design a glider that could fly a person and was able to fly long distances.

Otto Lilienthal was fascinated by the idea of flight. Based on his studies of birds and how they fly, he wrote a book on aerodynamics that was published in 1889 and this text was used by the Wright Brothers as the basis for their designs.

After more than 2500 flights, Otto Lilienthal was killed when he lost control because of a sudden strong wind and crashed into the ground.

1891 Samuel Langley

Samuel Langley was physicist and astronomer who realized that power was needed to help man fly. Langley conducted experiments using whirling arms and steam motors. He built a model of a plane, which he called an aerodrome, that included a steam-powered engine. In 1891, his model flew for 3/4s of a mile before running out of fuel.

Samuel Langley received a $50,000 grant to build a full sized aerodrome. It was too heavy to fly and it crashed. He was very disappointed. He gave up trying to fly. His major contributions to flight involved attempts at adding a power plant to a glider. He was also well known as the director of the Smithsonian Institute in Washington, DC.

Model of Langley Aerodrome

1894 Octave Chanute

Octave Chanute was a successful engineer who undertook the invention of airplanes as a hobby, after being inspired by Otto Lilienthal. Chanute designed several aircraft, the Herring - Chanute biplane was his most successful design and formed the basis of the Wright biplane design.

Octave Chanute published "Progress in Flying Machines" in 1894. It gathered and analyzed all the technical knowledge that he could find about aviation accomplishments. It included all of the world's aviation pioneers. The Wright Brothers used this book as a basis for much of their experiments. Chanute was also in contact with the Wright Brothers and often commented on their technical progress.

1903 The Wright Brothers - First Flight

Orville Wright and Wilbur Wright were very deliberate in their quest for flight. First, they spent many years learning about all the early developments of flight. They completed detailed research of what other early inventors had done. They read all the literature that was published up to that time. Then, they began to test the early theories with balloons and kites. They learned about how the wind would help with the flight and how it could affect the surfaces once up in the air.

1894 Octave Chanute

Octave Chanute was a successful engineer who undertook the invention of airplanes as a hobby, after being inspired by Otto Lilienthal. Chanute designed several aircraft, the Herring - Chanute biplane was his most successful design and formed the basis of the Wright biplane design.

Octave Chanute published "Progress in Flying Machines" in 1894. It gathered and analyzed all the technical knowledge that he could find about aviation accomplishments. It included all of the world's aviation pioneers. The Wright Brothers used this book as a basis for much of their experiments. Chanute was also in contact with the Wright Brothers and often commented on their technical progress.

1903 The Wright Brothers - First Flight

Orville Wright and Wilbur Wright were very deliberate in their quest for flight. First, they spent many years learning about all the early developments of flight. They completed detailed research of what other early inventors had done. They read all the literature that was published up to that time. Then, they began to test the early theories with balloons and kites. They learned about how the wind would help with the flight and how it could affect the surfaces once up in the air.

The next step was to test the shapes of gliders much like George Cayley did when he was testing the many different shapes that would fly. They spent much time testing and learning about how gliders could be controlled.

The Wright Brothers designed and used a wind tunnel to test the shapes of the wings and the tails of the gliders. After they found a glider shape that consistently would fly in the tests in the North Carolina Outer Banks dunes, then they turned their attention to how to create a propulsion system that would create the lift needed to fly.

The early engine that they used generated almost 12 horsepower.

The "Flyer" lifted from level ground to the north of Big Kill Devil Hill, at 10:35 a.m., on December 17, 1903. Orville piloted the plane which weighed six hundred and five pounds.

The first heavier-than-air flight traveled one hundred twenty feet in twelve seconds. The two brothers took turns during the test flights. It was Orville's turn to test the plane, so he is the brother that is credited with the first flight.

Humankind was now able to fly! During the next century, many new airplanes and engines were developed to help transport people, luggage, cargo, military personnel and weapons. The 20th century's advances were all based on this first flight at Kitty Hawk by the American Brothers from Ohio.

Aircraft Categories and classification

Heavier than air

Heavier than air aircraft, or aerodynes, include autogyros, gyrodynes, helicopters, powered lifts, and conventional fixed-wing aircraft (aeroplanes). Fixed-wing aircraft generally use an internal-combustion engine in the form of a piston engine (with a propeller) or a turbine engine (jet or turboprop), to provide thrust that moves the craft forward through the air. The movement of air over the wings produces lift that causes the aircraft to fly. Exceptions include gliders which have no engines and gain their thrust, initially, from winches or tugs and then from gravity and thermal currents. For a glider to maintain its forward speed it must descend in relation to the air (but not necessarily in relation to the ground). Helicopters and autogyros use a spinning rotor (a rotary wing) to provide lift; helicopters also use the rotor to provide thrust. Gyrodynes are aircraft intermediate between helicopters and autogyros, whose rotor is sometimes powered (often by a jet at its tips) but which do not have a tail rotor. Heliplanes are combination aircraft with both a rotor and wings; they can take off and land vertically, and hover, like a helicopter, but use their wings for high speed flight. The abbreviation "VTOL" is applied to aircraft that can take off and land vertically. "STOL" stands for Short Take Off and Landing.

Lighter than air

Lighter than air aerostats: balloons and airships. Aerostats use buoyancy to float in the air in much the same manner as ships float on the water. In particular, these aircraft use a relatively low density gas such as helium, hydrogen or heated air, to displace the air around the craft. The distinction between a balloon and an airship is that an airship has some means of controlling both its forward motion and steering itself, while balloons are carried along with the wind.

Types of aircraft

1. By design

A first division by design among aircraft is between lighter-than-air, aerostat, and heavier-than-air aircraft, aerodyne.

Examples of lighter-than-air aircraft include non-steerable balloons, such as hot air balloons and gas balloons, and steerable airships (sometimes called dirigible balloons) such as blimps (that have non-rigid construction) and rigid airships that have an internal frame. The most successful type of rigid airship was the Zeppelin. Several accidents, such as the Hindenburg fire at Lakehurst, NJ, in 1937 led to the demise of large rigid airships due to safety fears.

In heavier-than-air aircraft, there are two ways to produce lift: aerodynamic lift and engine lift. In the case of aerodynamic lift, the aircraft is kept in the air by wings or rotors (see aerodynamics). With engine lift, the aircraft defeats gravity by use of vertical thrust. Examples of engine lift aircraft are rockets, and VTOL aircraft (powered lift aircraft) such as the Hawker Siddeley Harrier.

Among aerodynamically lifted aircraft, most fall in the category of fixed-wing aircraft where horizontal airfoils produce lift by deflecting air downward to create an equal and opposite upward force according to Newton's third law of motion.

The forerunner of these type of aircraft is the kite. Kites depend upon the tension between the cord which anchors it to the ground and the force of the wind currents. Much aerodynamic work was done with kites until test aircraft, wind tunnels and now computer modelling programs became available.

In a "conventional" configuration, the lift surfaces are placed in front of a control surface or tailplane. The other configuration is the canard where small horizontal control surfaces are placed forward of the wings, near the nose of the aircraft. Canards are becoming more common as supersonic aerodynamics grows more mature and because the forward surface contributes lift during straight-and-level flight.

A collection of NASA test aircraft

The number of lift surfaces varied in the pre-1950 period, as biplanes (two wings) and triplanes (three wings) were numerous in the early days of aviation. Subsequently most aircraft are monoplanes. This is principally an improvement in structures and not aerodynamics.

Other possibilities include the delta wing, where lift and horizontal control surfaces are often combined, and the flying wing, where there is no separate vertical control surface (e.g., the B-2 Spirit).

A variable-geometry wing (or "swing-wing") has also been employed in a few examples of combat aircraft, such as the F-111, Panavia Tornado, F-14 Tomcat and B-1 Lancer, among others.

The lifting body configuration is where the body itself produce lift. So far, the only significant practical application of the lifting body is in the Space Shuttle, but many aircraft generate lift from nothing other than wings alone.

A second category of aerodynamically lifted aircraft are the rotary-wing aircraft. Here, the lift is provided by rotating aerofoils or rotors. The best-known examples are the helicopter, the autogyro and the tiltrotor aircraft (such as the V-22 Osprey). Some craft have reaction-powered rotors with gas jets at the tips but most have one or more lift rotors powered from engine-driven shafts.

A further category might encompass the wing-in-ground-effect types, for example the Russian ekranoplan also nicknamed the "Caspian Sea Monster" and hovercraft; most of the latter employing a skirt and achieving limited ground or water clearance to reduce friction and achieve speeds above those achieved by boats of similar weight.

A recent innovation is a completely new class of aircraft, the fan wing. This uses a fixed wing with a forced airflow produced by cylindrical fans mounted above. It is (2005) in development in the United Kingdom.

2. By propulsion

Some types of aircraft, such as the balloon or glider, do not have any propulsion. Balloons drift with the wind, though normally the pilot can control the altitude either by heating the air or by releasing ballast, giving some directional control (since the wind direction changes with altitude). For gliders, takeoff takes place from a high location, or the aircraft is pulled into the air by a ground-based winch or vehicle, or towed aloft by a powered "tug" aircraft. Airships combine a balloon's buoyancy with some kind of propulsion, usually propeller driven.

Until World War II, the internal combustion piston engine was virtually the only type of propulsion used for powered aircraft. (See also: Aircraft engine.) The piston engine is still used in the majority of aircraft produced, since it is efficient at the lower altitudes used by small aircraft, but the radial engine (with the cylinders arranged in a circle around the crankshaft) has largely given way to the horizontally-opposed engine (with the cylinders lined up on two sides of the crankshaft). Water cooled V engines, as used in automobiles, were common in high speed aircraft, until they were replaced by jet and turbine power. Piston engines typically operate using avgas (Avgas is a high-octane fuel used for aircraft and, in the past, racing cars. Avgas is a portmanteau for aviation gasoline, as distinguished from mogas (motor gasoline), which is the everyday gasoline used in cars. Avgas is used in aircraft that use piston or Wankel engines; gas turbines can operate on avgas, but typically do not. Turbine and diesel engines are designed to use kerosene-based jet fuel.)or regular gasoline, though some new ones are being designed to operate on diesel or jet fuel. Piston engines normally become less efficient above 7,000-8,000 ft (2100-2400 m) above sea level because there is less oxygen available for combustion; to solve that problem, some piston engines have mechanically powered compressors (blowers) or turbine-powered turbochargers or turbonormalizers that compress the air before feeding it into the engine; these piston engines can often operate efficiently at 20,000 ft (6100 m) above sea level or higher, altitudes that require the use of supplemental oxygen or cabin pressurization.

A turboprop-engined DeHavilland Twin Otter adapted as a floatplane

Pressurised aircraft, however, are more likely to use the turbine engine, since it is naturally efficient at higher altitudes and can operate above 40,000 ft. Helicopters also typically use turbine engines. In addition to turbine engines like the turboprop and turbojet, other types of high-altitude, high-performance engines have included the ramjet and the pulse jet. Rocket aircraft have occasionally been experimented with. They are restricted to rather specialised niches, such as spaceflight, where no oxygen is available for combustion (rockets carry their own oxygen).

3. By use

The major distinction in aircraft usage is between military aviation, which includes all uses of aircraft for military purposes (such as combat, patrolling, search and rescue, reconnaissance, transport, and training), and civil aviation, which includes all uses of aircraft for non-military purposes.

Fixed-Wing Aircraft

A fixed-wing aircraft is a heavier-than-air craft where movement of the wings in relation to the aircraft is not used to generate lift. The term is used to distinguish from rotary-wing aircraft, or ornithopters, where the movement of the wing surfaces relative to the aircraft generates lift. Modern jet transport aircraft take off at roughly 180 mph (290 km/h), and cruise at over 500 mph (800 km/h). Fixed-wing aircraft are commonly called airplanes in North America (the U.S. and Canada), and aeroplanes in Commonwealth countries (other than Canada) and Ireland. These terms are derived from Greek aéros- ("air") and -plane [1] . Both terms are often shortened to just planes.

Two necessities for all fixed-wing aircraft (as well as rotary-wing aircraft) are air flow over the wings for lifting of the aircraft, and an open area for landing. The majority of aircraft, however, also need an airport with the infrastructure to receive maintenance, restocking, refueling and for the loading and unloading of crew, cargo and/or passengers. While the vast majority of aircraft land and take off on land, some are capable of take off and landing on ice, snow and calm water.

The aircraft is the second fastest method of transport, after the rocket. Commercial jet aircraft can reach up to 900 km/h. Single-engined aircraft are capable of reaching 175 km/h or more at cruise speed. Supersonic aircraft (military, research and a few private aircraft) can reach speeds faster than sound. The speed record for a plane powered by an air-breathing engine is currently held by the experimental NASA X-43, which reached nearly ten times the speed of sound.

The biggest aircraft currently in service is Antonov An-225, while the fastest currently in production is the Mikoyan MiG-31. The biggest supersonic jet ever produced and currently in service is Tupolev-160.

Types of fixed-wing aircraft

Gliders

Gliders or sailplanes are aircraft designed for unpowered flight. Most gliders are intended for use in the sport of gliding and have high aerodynamic efficiency: lift-to-drag ratios may exceed 70 to 1. The energy for sustained gliding flight must be obtained through the skillful exploitation of naturally occurring air movements in the atmosphere. Glider flights of thousands of kilometres at average speeds over two-hundred kilometres per hour have been achieved.

Schleicher ASH-25 two-seat open class glider

Propeller aircraft

Smaller and older propeller aircraft make use of reciprocating internal combustion engines that turns a propeller to create thrust. They are quieter than jet aircraft, but they fly at lower speeds, and have lower load capacity compared to similar sized jet powered aircraft. However, they are significantly cheaper and much more economical than jets, and are generally the best option for people who need to transport a few passengers and/or small amounts of cargo. They are also the aircraft of choice for pilots who wish to own an aircraft.

Turboprop aircraft are a halfway point between propeller and jet: they use a turbine engine similar to a jet to turn propellers. These aircraft are popular with commuter and regional airlines, as they tend to be more economical on shorter journeys.

A Cessna 177 propeller-driven general aviation aircraft

Jet aircraft

Jet aircraft make use of turbines for the creation of thrust. These engines are much more powerful than a reciprocating engine. As a consequence, they have greater weight capacity and fly faster than propeller driven aircraft. One drawback, however, is that they are noisy; this makes jet aircraft a source of noise pollution. However, turbofan jet engines are quieter, and they have seen widespread usage partly for that reason.

An Air France Boeing 777, a modern passenger jet.

Supersonic jet aircraft

Supersonic aircraft, such as military fighters and bombers, Concorde, and others, make use of special turbines (often utilizing afterburners), that generate the huge amounts of power for flight faster than the speed of the sound. The design problems for supersonic aircraft are substantially different to those for sub-sonic aircraft.

Flight at supersonic speed creates more noise than flight at subsonic speeds, due to the phenomenon of sonic booms (The term sonic boom is commonly used to refer to the shocks caused by the supersonic flight of military aircraft). This limits supersonic flights to areas of low population density (Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, humans in particular) or open ocean. When approaching an area of heavier population density, supersonic aircraft are obliged to fly at subsonic speed.

Rotorcraft

Rotorcraft is a category of heavier-than-air flying machines that use lift generated by wings that revolve around a mast called rotor blades. Several rotor blades mounted to a single mast is referred to as a rotor. Rotorcraft may also include the use of static lifting surfaces, but the primary distinguishing feature being lift provided by one or more rotors. Rotorcraft include helicopters, autogyros, gyrodynes and tiltrotors.

Helicopter

A helicopter is an aircraft which is lifted and propelled by one or more horizontal rotors consisting of two or more rotor blades. Helicopters are classified as rotorcraft to distinguish them from fixed-wing aircraft because the helicopter derives its source of lift from the rotor

blades rotating around a mast. In fact, the word 'helicopter' originates from the Greek words elikoeioas (helical or spiral) and pteron (wing or feather).

The primary advantages of the helicopter are due to its rotor, which provides lift in a vertical direction, giving it the ability to take off and land vertically and to maintain a steady hover in the air over a single point on the ground. This allows the helicopter to land and take off from pinnacles and confined areas that airplanes are not able to take off from, including heliports in the middle of busy cities and rugged terrain in remote areas. The helicopter is used for rescue, medical evacuation and as an observation platform. Other operations that involve the use of helicopters are fire fighting, tours, as an aerial crane, logging, personnel transport, electronic news gathering, law enforcement, military and for pleasure.

Monoplane

A monoplane is an aircraft with one main set of wing surfaces, in contrast to a biplane or triplane.

The main distinction in types of monoplane is how the wings attach to the fuselage:

low-wing, the wing lower surface is level with the bottom of the fuselage mid-wing, the wing is mounted mid-way up the fuselage shoulder-wing, the wing is mounted above the fuselage middle high-wing, the wing upper surface is level with the top of the fuselage parasol, the wing is mounted above the fuselage (now rare)

The low-wing of a de Havilland Dove.

The mid-wing of a de Havilland Vampire T11.

The high-wing of a de Havilland Canada Dash 8

The parasol wing of a Dornier Do 24 flying boat

Monoplanes then went out of fashion, and remained so until the 1930s. This was by no means as strange as it might seem in retrospect. In the days when most aeroplane wings were thin, lightly built structures, braced by steel wire or cables - the biplane wing had very real stuctural and aerodynamic advantages. Early monoplane wings tended to be liable to twist in flight, rendering proper lateral control very difficult. They were also much more liable to breakage in flight.

Once all metal construction and the cantilever wing became common, however, the day of the biplane very quickly ended, and the monoplane became the usual configuration for an aeroplane. Most military aircraft of WW2 were monoplanes, as have been virtually all piston and jet powered aircraft since.

Biplane

A biplane is a fixed-wing aircraft with two main wings of similar spans, normally one mounted above, and the other level with the underside of the fuselage. The first powered heavier-than-air aircraft, the Wright brothers' Wright Flyer, used a biplane design, as did most airplanes in the early years of aviation.

Aircraft built with two main wings (or three in a triplane) can usually lift more than can a similarly sized monoplane of similar wing-span, but most biplanes also have a third horizontal surface, either a tailplane or a foreplane, to control the pitch, or angle of attack of the aircraft.

Biplanes were most successful in the early days of aviation when the wing structures needed to be strengthened by external bracing wires. The biplane configuration allowed the two wings to be braced against one another, increasing structural strength and rigidity. Wire braced monoplanes tended to suffer from overly flexible wings, resulting in poor lateral control, and a greater risk of wing failure. Another advantage of biplane wings is that a given wing area requires a shorter wing span, which tends to afford greater maneuverability.

The big disadvantage of the biplane layout (apart from the obvious one of increased drag) is that the two wings interfere with one another aerodynamically, each reducing the lift produced by the other. This means that for a given wing area the biplane produces more drag and less lift than a monoplane.

Hs123 biplane.

Triplane

A triplane is a fixed-wing aircraft equipped with three sets of wings, each roughly the same size and mounted one above the other. Typically, the lower set of wings would be level with the underside of the aircraft's fuselage, the middle set level with the top of the fuselage, and the top set supported above the fuselage on struts.

Triplanes have greater wing area than biplanes and monoplanes of similar wing span and chord, potentially offering increased lift and tighter turning radii .

A Fokker Dr.I, the best known triplane aircraft of World War I.

During World War I, some aircraft manufacturers turned to this configuration in an effort to gain extra maneuverability for fighter aircraft, at a penalty of greater drag and therefore lower

speed. In practice, triplanes generally offered inferior performance to biplanes, and only a few aircraft of this configuration reached production status.

The Sopwith Triplane was the first triplane to see service during World War I, but the best-known triplane of that conflict is the Fokker Dr.I, immortalised as the aircraft most closely identified with Manfred von Richthofen, the "Red Baron".

Aircraft parts

A typical fixed-wing aircraft can be divided into the following major parts:

A long cylinder, called a fuselage, with tapered ends to make its shape aerodynamically smooth. The fuselage carries the human flight crew, the passengers if the aircraft is a passenger aircraft, and/or the cargo if the aircraft carries cargo. The pilots, who are members of the flight crew, operate the aircraft from a cockpit located at the front of the fuselage and equipped with windows, controls, and instruments. Passengers and cargo occupy most of the remaining available space in the fuselage.

A pair of long, narrow, flat, horizontal airfoils, called wings, that generate an aerodynamic lifting force to support the aircraft as it flies thanks to their interaction with surrounding air as the aircraft moves forward. The wings are always symmetrical about the long axis of the fuselage, and are attached to the fuselage roughly at its midpoint in most cases. The wings also stabilize the aircraft about its roll axis and control its rotation about that axis.

A small wing mounted vertically at the top rear of the fuselage, called a vertical stabilizer. The vertical stabilizer is used to stabilize the aircraft about its yaw axis (the axis in which the aircraft turns from side to side) and to control its rotation along that axis. Some aircraft have multiple vertical stabilizers.

A pair of small horizontal wings used mainly to stabilize the aircraft about its pitch axis (the axis around which the aircraft tilts upward or downward). The horizontal stabilizers are symmetrical and usually mounted near the rear of the fuselage, or at the top of the vertical stabilizer.

One or more engines, propulsion units that provide thrust to push the aircraft forward through the air. The most common propulsion units are propellers, powered by reciprocating or turbine engines, and jet engines, which provide thrust directly from the engine and usually also from a large fan mounted within the engine. When the number of engines is even, they are distributed symmetrically about the roll axis of the aircraft (the long axis of the fuselage); when the number is odd, the odd engine is usually mounted along the centerline of the fuselage.

Landing gear , a set of wheels, skids, or floats (depending on the intended landing surface for the aircraft) that support the aircraft while it is on the ground.

The Parts of an Airplane

Parts of a Plane

The body of the plane is called the fuselage. It is generally a long tube shape. The wheels of a plane are called the landing gear. There are two main wheels on either side of the plane fuselage. Then there is one more wheel near the front of the plane. The brakes for the wheels are like the brakes for cars. They are operated by pedals, one for each wheel. Most landing gear can be folded into the fuselage during the flight and opened for landing.

All planes have wings. The wings are shaped with smooth surfaces. There is a curve to the wings which helps push the air over the top more quickly than it goes under the wing. As the wing moves, the air flowing over the top has farther to go and it moves faster than the air underneath the wing. So the air pressure above the wing is less than below it. This produces the upward lift. The shape of the wings determines how fast and high the plane can fly. Wings are called airfoils.

The hinged control surfaces are used to steer and control the airplane. The flaps and ailerons are connected to the backside of the wings. The flaps slide back and down to increase the surface of the wing area. They also tilt down to increase the curve of the wing. The slats move out from the front of the wings to make the wing space larger. This helps to increase the lifting force of the wing at slower speeds like takeoff and landing. The ailerons are hinged on the wings and move downward to push the air down and make the wing tilt up. This moves the plane to the side and helps it turn during flight. After landing, the spoilers are used like air brakes to reduce any remaining lift and slow down the airplane.

The tail at the rear of the plane provides stability. The fin is the vertical part of the tail. The rudder at the back of the plane moves left and right to control the left or right movement of the plane. The elevators are found at the rear of the plane. They can be raised or lowered to change the direction of the plane's nose. The plane will go up or down depending on the direction of that the elevators are moved.

Forces in Flight

Several forces are particularly important for flight:

Propulsive thrust : (except in gliders) Lift : Created by wings

Drag : Created by airflow Weight : (created by gravity) Buoyancy : for lighter than air flight

Aircraft controls

A number of fairly standardized controls allow pilots to direct aircraft in the air. The controls found in a typical fixed-wing aircraft are as follows:

A yoke or control stick, which controls rotation of the aircraft about the pitch and roll axes. A yoke resembles a kind of steering wheel, and a control stick is just a simple rod with a handgrip. The pilot can pitch the aircraft downward by pushing on the yoke or stick, and pitch the aircraft upward by pulling on it. Rolling the aircraft is accomplished by turning the yoke in the direction of the desired roll, or by tilting the control stick in that direction. Pitch changes are used to adjust the altitude and speed of the aircraft; roll changes are used to make the aircraft turn.

Rudder pedals, which control rotation of the aircraft about the yaw axis. There are two pedals that pivot in such a way that pressing one forward moves the other backward, and vice versa. The pilot presses on the right rudder pedal to make the aircraft yaw to the right, and on the left pedal to make it yaw to the left. The rudder is used mainly to balance the aircraft in turns, or to compensate for winds or other effects that tend to turn the aircraft about the yaw axis.

A throttle, which adjusts the thrust produced by the aircraft's engines. The pilot uses the throttle to increase or decrease the speed of the aircraft, and to adjust the aircraft's altitude (higher speeds cause the aircraft to climb, lower speeds cause it to descend). In some aircraft the throttle is literally a single lever that controls thrust; in others, adjusting the throttle effectively means adjusting a number of different engine controls simultaneously in a coordinated way. Aircraft with multiple engines usually have individual throttle controls for each engine.

Brakes , used to slow and stop the aircraft on the ground, and sometimes for turns on the ground as well.

1. Yoke (aircraft)

The control yoke of a Boeing 737 aircraft.

In aviation, a yoke is a control used in most fixed-wing aircraft, which might be referred to as a steering wheel by people not familiar with aircraft.

The aviator uses the yoke to control the attitude of the plane, usually in both pitch and roll. Rotating the wheel on the yoke rolls the aircraft and pulling or pushing the yoke pitches the aircraft in a natural sense. There are also computer input devices designed to simulate a yoke, intended for flight simulators. Yokes in most larger aircraft are linked to stick shakers which are designed to help indicate and recover from stalling conditions.

The control stick or control column found on modern fighter aircraft is not the same as a yoke. The control stick is a roughly vertical rod or column that is pushed forward and aft for pitch control of the aircraft and left and right for roll control.

2. Aircraft Rudders

The tail of a KC135 Stratotanker, with the rudder marked

On an aircraft, the rudder is called a "control surface" along with the rudder-like elevator (attached to horizontal tail structure) and ailerons (attached to the wings) that control pitch and roll. The rudder is usually attached to the fin (or vertical stabilizer) which allows the pilot to control yaw in the horizontal axis, ie change the horizontal direction in which the nose is pointing. The rudder's direction is manipulated with the movement of foot pedals by the pilot.

In practice, both aileron and rudder control input are used together to turn an aircraft, the ailerons imparting roll, the rudder imparting yaw, and also compensating for a phenomenon called adverse yaw. Adverse yaw is readily seen if the ailerons alone are used for a turn. The downward moving aileron acts like a flap, generating more lift for one wing, and therefore more drag. Initially, this drag yaws the aircraft in the direction opposite to the desired course. A rudder alone will turn a conventional fixed wing aircraft, but much more slowly than if ailerons are also used in conjunction. Use of rudder and ailerons together produces co-ordinated turns, in which the longitudinal axis of the aircraft is in line with the arc of the turn, neither slipping (under-ruddered), nor skidding (over-ruddered). Improperly ruddered turns at low speed can precipitate a spin which can be dangerous at low altitudes.

Sometimes pilots may intentionally operate the rudder and ailerons in opposite directions in a maneuver called a forward slip. This may be done to overcome crosswinds and keep the fuselage in line with the runway, or to more rapidly lose altitude by increasing drag, or both.

3. Throttle

A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. In an engine, the engine's power can be increased or decreased by the restriction of inlet gases i.e. by the use of a throttle. The term throttle has come to refer, informally and incorrectly, to any mechanism by which the power or speed of an engine is regulated.

Internal combustion engines

In a petrol internal combustion engine, the throttle is a valve that directly regulates the amount of air entering the engine. In a motor vehicle the control used by the driver to regulate power is sometimes called the throttle pedal.

The throttle is typically a butterfly valve. In a fuel-injected engine, the throttle valve is housed in the throttle body. In a carbureted engine, it is found in the carburetor.

When a throttle is wide open, the intake manifold is usually at ambient atmospheric pressure. When the throttle is partially closed, a manifold vacuum develops as the intake drops below ambient pressure.

Usually the throttle valve is mechanically linked with the throttle pedal or lever. In vehicles with electronic throttle control, the throttle valve is electronically controlled, which allows the ECU greater possibilities in reducing air emissions.

Diesel internal combustion engines lack a butterfly valve in the intake tract and instead regulate engine power via direct control of the quantity of fuel injected into the cylinder during the power stroke. I.e. diesel engines do not have a throttle.

Other engines

Most engines have some kind of throttle control, though the particular way that power is regulated is often different.

Liquid rockets are throttled by controlling the pumps which send liquid fuel and oxidizer to the combustion chamber. Solid rockets are more difficult to throttle, but some may have mechanisms for this.

In a jet engine, engine output is also directly controlled by changing the amount of fuel flowing into the combustion chamber, usually with an autothrottle.

Autothrottle

An autothrottle (automatic throttle) allows a pilot to control the power setting of an aircraft's engines by specifying a desired flight characteristic, rather than directly controlling fuel flow. These systems can conserve fuel and extend engine life by metering the precise amount of fuel required to attain a specific target indicated air speed, or the assigned power for different phrases of flight. A/T and AFDS (Auto Flight Director System) work together to fulfill the whole flight plan and greatly reduce pilots work load.

Simply put, when engaged AutoThrottle replaces manual throttle input with an electronic (or in older systems, mechanical) feedback loop that controls fuel flow to the engines. This reduces pilot workload as well as being more accurate than manually adjusting fuel flow.

4. Air brake (aircraft)

In aeronautics air brakes are a type of flight control used on aircraft to reduce speed during landing.

Air brakes differ from spoilers in that air brakes are designed to increase drag while making little change to lift, whereas spoilers greatly reduce lift while making little change to drag.

This KLM cityhopper Fokker 70 still has its spoilers (not air brakes) deployed (the cream-coloured panels projecting above the top surface of the wing) after landing at Bristol

International Airport, England.

Often, both characteristics are desirable and are combined - most modern airliner jets feature combined spoiler and airbrake controls. On landing, the deployment of these spoilers causes a dramatic loss of lift and hence the weight of the aircraft is transferred from the wings to the undercarriage, allowing the wheels to be mechanically braked with much less chance of skidding. In addition, the form drag created by the spoilers directly assists the braking effect. Reverse thrust is also used to help slow the aircraft after landing.

The British Blackburn Buccaneer naval strike aircraft designed in the 1950s had a tail cone that was split and could be hydraulically opened to the sides to act as a variable air brake. It also helped reduced the length of the aircraft in the confined space on an aircraft carrier.

Airbrake on a British Buccaneer naval strike aircraft

Thrust reversal

KLM Fokker 70 with reverse thrust applied. The two surfaces behind the engine can be seen in the deployed position, diverting the engine exhaust gases forward

Thrust reverser on a Turbo-Union RB199 jet engine

Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's output so that the thrust produced is directed forward, rather than aft. This acts against the forward travel of the aircraft, providing deceleration. Thrust reversers are used by many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. It is also available on many propeller aircraft through reversing the controllable pitch propellers to a negative angle.

Parasitic drag

Parasitic drag (also called parasite drag) is drag caused by moving a solid object through a fluid. Parasitic drag is made up of many components, the most prominent being form drag. Skin friction and interference drag are also major components of parasitic drag.

In aviation, induced drag tends to be greater at lower speeds because a high angle of attack is required to maintain lift. However, as speed increases the induced drag becomes much less, but parasitic drag necessarily increases because the fluid is flowing faster. At even higher speeds in the transonic, wave drag enters the picture. Each of these forms of drag changes in proportion to the others based on speed. The combined overall drag curve therefore shows a minimum at some airspeed - an aircraft flying at this speed will be at or close to its optimal efficiency. Pilots will use this speed to maximize endurance (minimum fuel consumption), or maximise gliding range in the event of an engine failure.

Form drag

Form drag, profile drag, or pressure drag, arises because of the form of the object. The general size and shape of the body is the most important factor in form drag - bodies with a larger apparent cross-section will have a higher drag than thinner bodies. Sleak designs, or designs that are streamlined and change cross-sectional area gradually are also critical for achieving minimum form drag. In some cases, cooling systems can be a serious source of drag, and Evaporative cooling was developed to remedy that. Form drag follows the drag equation, meaning that it rises with the square of speed, and thus becomes more important for high speed aircraft.

Profile Drag (Pxp): depends on the longitudinal section of the body. A diligent choice of body profile is more than essential for low drag coefficient. Streamlines should be continuous and separation of the boundary layer with its attendant vortices should be avoided.

Interference drag

Interference drag arises from vortices. Whenever two surfaces meet at a sharp angle on an airplane, the airflow has a tendency to form a vortex. Accelerating the air into this vortex causes drag on the plane, and the resulting low pressure area behind the plane also contributes. Thus, the primary method of reducing interference drag is eliminating sharp angles by adding fairings which smooth out any sharp angles on the aircraft by forming fillets. Interference drag is also created by closly spaced parallel surfaces such as the wings of a biplane or triplane, or the facing surfaces of an external load (such as an external fuel tank or weapon) and the fuselage or wing. As with other components of parasitic drag, interference drag follows the drag equation and rises with the square of the velocity.

Skin friction

Skin friction arises from the friction of the fluid against the "skin" of the object that is moving through it. Skin friction is a function of the interaction between the fluid and the skin of the body, as well as the wetted surface, or the area of the surface of the body that would become wet if sprayed with water flowing in the wind. As with other components of parasitic drag, skin friction follows the drag equation and rises with the square of the velocity.

Split control surfaces

One interesting airbrake design is the deceleron, a special kind of aileron that functions normally in flight but can split in half such that the top half goes up as the bottom half goes down to brake. This technique was first used on the F-89 Scorpion and has since been used by Northrop on several aircraft, including the B-2 Spirit.

Ailerons are hinged control surfaces attached to the trailing edge of the wing of a fixed-wing aircraft. They are used to control the aircraft in roll. The two ailerons are interconnected so that one goes down when the other goes up: the downgoing aileron increases the lift on its wing while the upgoing aileron reduces the lift on the other wing, producing a rolling moment about the aircraft's longitudinal axis. The word aileron is French for "little wing."

Ailerons are the trailing-edge control surface nearest the wing tip (although on some airliners they can also be found at the wing root). On this parked Piper Cherokee the aileron has

deflected downwards.

The space shuttle uses a similar system. The split rudder opens on landing to act as a speedbrake [1], as shown in the accompanying photo.

Space Shuttle Discovery just after touchdown at the end of mission STS-116

Helicopter flight controls

Flight controls

A typical helicopter has three separate flight control inputs. These are the cyclic, the collective, and the anti-torque pedals. Depending on the complexity of the helicopter, the cyclic and collective may be linked together by a mixing unit, a mechanical or hydraulic device that combines the inputs from both and then sends along the "mixed" input to the control surfaces to achieve the desired result.

Cyclic

The cyclic stick is usually located between the pilot's legs. The cyclic is so called because it changes the pitch of the rotor blades cyclically, that is the pitch of a given blade will be different depending upon its position as it rotates about the rotor head. The result is to tilt the rotor disk in a particular direction, resulting in the helicopter moving in that direction.

Collective

The collective is usually located on the pilot's left side. The collective changes the pitch of the rotor blades collectively or all at the same time, regardless of their position. Therefore, if a collective input is made, all the blades change equally, and the result is the helicopter increasing or decreasing in altitude.

Anti-torque pedals

The anti-torque pedals are located in the same position as the rudder pedals in an airplane, and serve a similar purpose, namely to control the direction in which the nose of the aircraft is pointed. Application of the pedal in a given direction changes the pitch of the tail rotor blades, increasing or reducing the thrust produced by the tail rotor and causing the nose to yaw in the direction of the applied pedal.

Flight conditions

There are two basic flight conditions for a helicopter. These are hovering and forward flight.

Hovering

Hovering is the most challenging part of flying a helicopter. This is because that while in a hover, a helicopter generates its own gusty air which acts against the fuselage and flight control surfaces. The end result is constant control inputs and corrections by the pilot to keep the helicopter where it is required to be. However, despite the actual complexity of the act itself, the control inputs themselves in a hover are quite simple. The cyclic is used to eliminate drift in the horizontal plane, that is to control forward and back, right and left. The collective is used to maintain altitude. The pedals are used to control nose direction or heading. It is the interaction of these controls that makes hovering so difficult, since an adjustment in any one control requires an adjustment of the other two, creating a cycle of constant correction.

Forward flight

Forward flight may be considered to be flight at airspeeds in excess of 40 KIAS, since is at this airspeed that most pitot-static airspeed systems become reliable. In forward flight a helicopter's flight controls behave more like that in a fixed-wing aircraft. Displacing the cyclic forward will cause the nose to pitch down, with a resultant increase in airspeed and loss of altitude. Aft cyclic will cause the nose to pitch up, slowing the helicopter and causing it to climb. The collective now becomes analogous to the throttle in an airplane. Increasing collective(power) while maintaining a constant airspeed will induce a climb while decreasing collective will cause a descent. Coordinating these two inputs, down collective plus aft cyclic or up collective plus forward cyclic, will result in airspeed changes while maintaining a constant altitude. The pedals serve the same function in both a helicopter and an airplane, to maintain balanced flight. This is done by applying a pedal input in whichever direction is necessary to center the ball in the turn and bank indicator. The following mnemonics may be used to recall changes necessary to speed up and to slow down during forward flight:

Flight instruments

Most aircraft are equipped with a standard set of flight instruments which give the pilot information about the aircraft's attitude, airspeed, and altitude.

Most aircraft have these seven basic flight instruments:

Altimeter Gives the aircraft's height (usually in feet or meters) above some reference level (usually sea-level) by measuring the local air pressure. It is adjustable for local barometric pressure (referenced to sea level) which must be set correctly to obtain accurate altitude readings.

Attitude indicator (also known as an artificial horizon) Shows the aircraft's attitude relative to the horizon. From this the pilot can tell whether the wings are level and if the aircraft nose is pointing above or below the horizon. This is a primary instrument for instrument flight and is also useful in conditions of poor visibility. Pilots are trained to use other instruments in combination should this instrument or its power fail.

Airspeed indicator Shows the aircraft's speed (usually in knots) relative to the surrounding air. It works by measuring the ram-air pressure in the aircraft's pitot tube. The indicated airspeed must be corrected for air density (which varies with altitude, temperature and humidity) in order to obtain the true airspeed, and for wind conditions in order to obtain the speed over the ground.

Magnetic compass Shows the aircraft's heading relative to magnetic north. While reliable in steady level flight it can give confusing indications when turning, climbing, descending, or accelerating due to the inclination of the earth's magnetic field. For this reason, the heading indicator is also used for aircraft operation. For purposes of navigation it may be necessary to correct the direction indicated (which points to a magnetic pole) in order to obtain direction of true north or south (which points to the earth's axis of rotation).

Heading indicator Also known as the directional gyro, or DG. Sometimes also called the gyrocompass, though usually not in aviation applications. Displays the aircraft's heading with respect to magnetic north. Principle of operation is a spinning gyroscope, and is therefore subject to drift errors (called precession) which must be periodically corrected by calibrating the instrument to the magnetic compass. In many advanced aircraft, the heading indicator is replaced by a Horizontal Situation Indicator (HSI) which provides the same heading information, but also assists with navigation.

Turn and bank indicator or turn coordinatorThe turn and bank indicator, also called the turn and slip indicator, displays direction of turn and rate of turn. Internally mounted inclinometer displays 'quality' of turn, i.e. whether the turn is correctly coordinated, as opposed to an uncoordinated turn, wherein the aircraft would be in either a slip or a skid. Replaced in the late sixties and early seventies by the newer turn coordinator, the turn and bank is typically only seen in aircraft manufactured prior to that time, or in Gliders manufactured in Europe.A turn coordinator displays rate and direction of roll while the aircraft is rolling; displays rate and direction of turn while the aircraft is not rolling. Internally mounted inclinometer also displays quality of turn. Replaced the older turn and bank indicator.

Vertical speed indicator Also sometimes called a variometer. Senses changing air pressure and displays that information to the pilot as a rate of climb or descent, usually in feet per minute or meters per second.

Six basic instruments in a light twin-engine airplane arranged in the basic-T. From top left: airspeed indicator, attitude indicator, altimeter, turn coordinator, heading indicator, and

vertical speed indicator

The flight instruments of a Slingsby T-67 Firefly two-seat light airplane. The basic T is present on the left side primary pilot station

Schempp-Hirth Janus-C glider Instrument panel equipped for "cloud flying", with instruments configured in the basic-T. The turn and bank indicator is top center. The heading indicator is

replaced by a GPS-driven computer with wind and glide data, driving two electronic variometer displays to the right.

Arrangement in instrument panel

Most aircraft built since about 1953 have four of the flight instruments located in a standardized arrangement known as the "basic T". The attitude indicator is in top center, airspeed to the left, altitude to the right and heading indicator under the attitude indicator. The other two, turn-coordinator and vertical-speed, are usually found under the airspeed and altitude, but are given more latitude in placement. The magnetic compass will be above the instrument panel, often on the windscreen centerpost. In newer aircraft with glass cockpit instruments the layout of the displays conform to the basic T arrangement.

Reference: http://en.wikipedia.org/wiki/Flight