NUMBER 3 IN THE SERIES – Flying Circus Above and Beyond. OUT NOW!
In the Cockpit
So you've submitted a flight plan; you've called the tower for clearance; you know you have 80,000lbs of thrust and a wingspan of 99ft; you've lit engine 1 of your Vulcan so you now have flames leaping around the vicinity of thousands of litres of highly flammable liquid. So far so good. You know what you're doing, right? Check here.
AEROPLANE PARTS & FUNCTIONS
PITCH, ROLL & YAW
IN AND OUT OF THE COCKPIT: AN A-Z
AD Anno Domini is Latin for “in the year of the Lord” and marks the year of Jesus Christ’s birth. This is used as a starting point for our dates. The year 2025, for example, is two thousand and twenty-five years after the birth of Jesus.
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Absolute altitude The height of the aircraft above ground level, compared with true altitude, which is the height above sea level.
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Aerodynamics This refers to how air moves around an object. It helps us create shapes that move smoothly, with as little air resistance as possible. Aerofoil is a shape that allows an aeroplane or a bird to fly. Wings are curved on top and flat underneath. When a wing moves through air, the air moves faster over the top and slower underneath. This difference in speed creates a force that lifts the aeroplane. In 1738, Swiss scientist Daniel Bernoulli showed that when air speeds up, its pressure is reduced. So the air going faster over the top of an aeroplane’s wing creates a slight suction which pulls upward on the wing. As long as the plane is moving, the air pressure above the wing is lower than below the wing, causing lift. The faster the plane moves, the greater this difference and the more lift the aeroplane receives. Thrust provides the forward motion that causes the air to move over the wing, so an aeroplane climbs because of a combination of thrust and lift.
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Afterburners A jet’s afterburner provides an extra boost of thrust. The pilot sends fuel under pressure to a ring within the exhaust cone of the aeroplane. Here, this raw fuel is ignited by the exhaust jet stream. The combustion thrusts the aircraft forwards. A flame or glow appears at the back of the jet.
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In normal cruising conditions without afterburners, an F-14A consumes around 600 to 800 gallons of fuel per hour. With afterburners lit, it consumes roughly twice as much fuel.
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Ailerons control the roll of an aeroplane. They are attached to the trailing edge of the wings. This results in the aeroplane rolling to one side or the other.
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Air traffic control (ATC) organises the flow of aircraft traffic using visual observation from the airport control tower and radar screens. The air traffic controllers look out of windows in a high tower. Their job is to prevent collisions and organise the movement of aircraft on the taxiways, runways and in the air within 5-10 nautical miles of the airport. A “non-towered airport” is an airport without a control tower or air traffic control (ATC) unit. The vast majority of the world’s airports are non-towered. In the United States, there are close to 20,000 non-towered airports compared to approximately 500 airports with control towers. The first airport control tower was established in Croydon, England, in 1920.
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Airbrakes These are special flaps on an Avro Vulcan’s wings that act like brakes. They create more resistance to the air, helping the plane slow down when it needs to land.
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Aircraft carrier A ship that serves as an airbase; it has a flight deck where aeroplanes and helicopters can land and take off. The first aircraft carriers were wooden ships used to deploy air balloons. Only certain types of aeroplane can land on aircraft carriers as there is limited space for take-off and landing.
Alternate This is an alternative airport which is a backup landing site if the intended destination is not available. All flights will have one on their flight plan.
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Alternative radio frequency If a frequency range has become unusable because of noise being created by jamming, the device using the frequency can be retuned to a new “alternative” frequency for communication.
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Angels Altitude in thousands of feet.
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Angle of attack The angle between the relative flow of wind and the front of the aeroplane’s wing.
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Apollo Sucellos This god combines the Roman god Apollo with the Celtic god Sucellos. This is an example of syncretism: the blending of elements of different belief systems when cultures come into contact with each other.
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Approach The phase of flight when the pilot intends to land on the runway. There are different types of approaches depending on whether the pilot is flying under visual flight rules or instrument flight rules.
Archaeologist This is a scientist who studies history by examining remains from the past that have been buried in the ground.
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Arresting gear / trip wire / capture system A mechanical system used to rapidly decelerate an aircraft as it lands on the deck of the aircraft carrier. Several steel wire ropes laid across the aircraft landing area catch a special hook on the tail of the aeroplane to slow it down.
​ATC See Air traffic control.
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ATIS (automated terminal information service) This provides current aerodrome information for departing and arriving aircraft.
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Attitude indicator This shows whether the aeroplane is pitching its nose up or down (see Pitch) and whether it is rolling to one side (see Roll). It was originally called the artificial horizon indicator.
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AWOL This is short for Absent Without Leave. It describes a situation where a service member has not been granted approval to leave but they are absent.
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Burner See Afterburner.
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Canopy Transparent enclosure over the cockpit.
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Capture system See Arresting gear.
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Chinook Made by Boeing, this twin-rotor helicopter entered service in 1982. It can land on almost any terrain as well as aircraft carriers. It can carry enormous payloads both underslung on its triple hooks or in its hold, including vehicles, water, and supplies. As well as carrying cargo and conducting emergency evacuations, it is an excellent Search and Rescue (SAR) aircraft.
Coffin corner This describes a dangerous situation where a plane is at high altitude, so the air is thin. There is less oxygen. The thinner the air, the faster an aeroplane must travel to generate lift. But where the air is very thin, an aeroplane may not be able to fly at its maximum speed. When the aeroplane reaches its top speed for the given altitude, if this is not fast enough to generate the extra airflow over the wing to maintain the lift it needs, it will lose control. However, if it slows down it risks a stall and loss of control, also due to insufficient airflow over the wing.
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Collective This controls a helicopter’s altitude. It affects all the rotor blades at the same time “collectively”. When it is raised, it causes the pitch angle of the disc to which the blades are attached, and therefore the blades themselves, to increase. This makes the helicopter rise. When the collective is lowered, it causes the opposite.
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Court martial When a service member in the military gets into trouble, they have to go to a trial in which other service members, like officers, decide what should be done.
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Cruising altitude The height in the sky which an aeroplane holds for most of its flight.
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Cyclic The helicopter’s control stick. Moving it in any direction makes the disc holding the rotor blades change pitch, which moves the helicopter left and right.
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Delta wing A wing shaped in the form of a triangle. Aeroplanes with a delta wing don’t usually have a separate tail wing so the ailerons and elevators are combined onto one control surface called an elevon.
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Downwind/Upwind Downwind is the direction the wind is going in and upwind is the direction the wind is coming from. If the wind is blowing from the northwest and blowing toward the southeast, then the upwind direction is northwest and the downwind direction is southeast.
Drag This is the force that pushes against an object as it moves through the air or water, like the air pushing against an aeroplane as it flies. If an aeroplane is configured for maximum drag, it has altered its outline to create as much air resistance as possible. This would slow it down.
Elevators influence the pitch; that is, the climb of the aeroplane. Elevators are usually on the tail wing of an aircraft. Changing the pitch means changing the direction of the nose of the aeroplane up or down. If it points up more, the way air passes under the aeroplane’s wings provides more lift making it go upwards. If the nose of the aeroplane drops, this reduces the lift provided by the air under the wings, and the aeroplane will start to accelerate downwards. These effects can be altered by an aeroplane changing its speed. Elevators are a primary control surface.
Elevon This is part of an aircraft’s wing that works like both an elevator and an aileron. It helps control the plane’s up-and-down movement (pitch) and also helps with turning the plane left or right (roll and yaw). Aeroplanes with delta wings often combine these functions in one part, the elevon.
Elliptical wing The elliptical shape of a Spitfire’s wing was developed by Reginald Mitchell for the British manufacturer, Supermarine, during the 1920s and 1930s. It was a semi-elliptical wing meaning just one edge was curved. This curvature allowed for a very thin wing to reduce drag but widening out nearer the root to accommodate a retracted undercarriage and guns. A similar elliptical wing had been designed by Heinkel but was refined and developed by Mitchell.
Fin rudder This controls the horizontal rotation of the aeroplane, that is, the yaw (see diagram at the beginning of this A-Z). It is the ailerons which roll the aircraft to the left and right, an action more akin to “steering”. Often, however, a left hand bank will be achieved with a combination of left rudder pedal, elevator, and ailerons (or elevons where elevators and ailerons are combined, for example, on a Vulcan).
Final approach A flight path running in the direction of the runway. It is intended to lead to the aeroplanes making a landing. See also Pattern.
Firmitas This is tenacity, strength of mind, and the ability to stick to one’s purpose. It is one of the Roman personal virtues, the qualities which Roman citizens aspired to. They are at the heart of Romanitas, the essence of being Roman. Firmitas is represented by the Hercules knot in classical art, particularly in architecture, as it stands for strength and stability.
Flaps These change drag and lift (see illustration at start of this Glossary).
Flaring Coming in to land, the nose of the plane is pitched up, slowing the descent rate and creating a softer touchdown.
Flight plan A flight plan is required prior to a flight which enters into an airspace covered by air traffic control. This may be to co-ordinate with other flights in a busy area or with military units. It is also needed for a flight across international borders. It is likely to include information such as aircraft identification, whether it is flying on instrument or visual flight rules, on-board equipment, cruising level, route to be followed, destination aerodrome, and fuel endurance.
Fly-by-wire This is the electrical technology in modern aircraft that has replaced the mechanical and hydraulic controls in older aircraft. Instead of using physical cables or rods to control the plane’s control surfaces (ailerons, rudder, elevators), the pilot sends electronic signals to a computer system which then moves the controls.
Four forces of flight These are lift, weight, thrust and drag.
Freeze-thaw When water freezes, it expands. If water has seeped into a crack in a rock, as it expands, it pushes the crack apart, making it larger. Eventually this breaks the rock.
Fuselage An aircraft’s main body section holding crew, passengers, or cargo.
G-forces Otherwise known as gravitational forces, these refer to the force of gravity. 1 G is the normal force of gravity we experience when we are stationary or moving slowly. Higher G-forces occur when we speed up, slow down, or rapidly change direction. 2 G means the force that is felt is twice the force of gravity. If a plane makes a sharp turn, the pilot may experience and feel much heavier than normal. Trained pilots can withstand up to 9 G for short periods.
Geiger counter A device for measuring radiation. The amount of radiation entering the Geiger counter chamber is indicated by a needle moving across a scale showing counts per minute.
Hangar A large building shaped to house aeroplanes.
Holding position A position where taxiing aircraft have to stop before entering the runway for take-off.
HUD (head-up display) A transparent display showing flight data enabling a pilot to be able to view information with the head positioned up and looking forward, instead of angled down looking at instruments. The cockpit of a F-117 Nighthawk has a Kaiser Electronics head-up display and the flight deck is equipped with a large video monitor which displays the infrared imagery from the aircraft’s on-board sensors.
Hypocaust This was a Roman heating system used to warm buildings and baths by heating air under the floor using a furnace (praefurnium) and circulating the hot air through channels under the floors and in the walls.
IMC See Instrument meteorological conditions.
Inertial navigation system This is a self-contained system; it doesn’t depend on signals from external nav-aids. First, the system records the starting point of an aircraft’s journey. It then records the heading, or direction of the aeroplane, using rotation sensors called gyroscopes. It uses motion sensors called accelerometers to detect the speed of the aircraft. Putting all this data together, the inertial navigation system (INS) calculates where the aeroplane is at any given point on the flight.
Infrared camera This measures short wave infrared radiation, which is felt as heat. Even if the image is not visible to the human eye, if it is emitting heat energy, the camera will detect it.
Instrument meteorological conditions (IMC) This is a flight category that describes weather conditions which require pilots to fly primarily by reference to instruments and therefore under instrument flight rules (IFR) rather than visual flight rules (VFR). If instrument failure occurs in IMC, such failure may affect airspeed indications, especially if the failure is due to a failure of the pitot-static system.
Integrity This is when you stick to your principles even when it’s difficult, inconvenient, or tempting not to.
Jamming Both radio and radar can be electronically jammed. This means the frequency being used by the aircraft for either of these has been filled with noise by the jammer so that the aircraft can no longer receive or send a signal. Aircraft can protect themselves by cloaking their outgoing signal with random noise, making it more difficult for a jammer to figure out the frequency that a radio or radar is operating on. They can also change the frequency they use.
Jet bridges These are extendable walkways that connect an airport to the door of an aircraft. They allow passengers to board and get off an aeroplane without going outside.
Knots This is the accepted unit of speed in aviation and shipping. A knot is one nautical mile per hour and one nautical mile is helpful for navigation because it equates to one minute of latitude. Using latitude and longitude coordinates is a good idea for long-distance travel where the curvature of the Earth becomes a factor in accurate measurement. To convert from knots to miles per hour, multiply the speed in knots by 1.151.
Landing gear This is the structure under an aeroplane that holds the wheels. In modern aeroplanes, it is usually retractable but in older ones, it’s fixed in place. Also see Undercarriage.
Latrones To play latrones, two players move pieces across the board. When a player’s piece is trapped between two of his opponent’s pieces, it is captured and removed from the board. The player who captures all of his opponent’s pieces wins the game. The winners of the game were called imperator, meaning commander. Many latrones boards have been found at a Roman site in Britain called Vindolanda.
Loop To achieve a perfect circle the pilot must juggle airspeed, pitch, pressure adjustments on the control surfaces, and visual checks to make sure the wing is tracing a perfect circle. Loops are one of the first aerobatic skills learned by a pilot and they help the pilot get accustomed to unusual pitch attitudes, rapidly changing airspeeds, and the effects of Gs (gravitational pressure caused by acceleration).
Mach 1 The speed of sound: 761.2 mph. Sometimes called the sound barrier. A “supersonic” aircraft is able to fly faster than the speed of sound. An aircraft flying at Mach 2 is flying at twice the speed that sound travels in air.
Maximum take-off weight Apart from its body, the weight of an aircraft is determined by how much fuel and cargo it is carrying. An aircraft must be at or under the maximum weight set by its manufacturer for a safe take-off due to the limits of its structural design.
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Measuring systems A Roman unit of distance was the mille passum, which translates to “thousand paces”. A pace was five Roman feet, meaning a Roman mile measured 5,000 feet. The Romans used milestones to mark distances. They can be found all over Roman Britain.
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Microbursts These are columns of sinking air producing divergent winds. These downdraughts can move as fast as 6,000 feet per minute, which is much faster than an aeroplane can climb. They can cause an aeroplane to lose height very quickly and be extremely dangerous.
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Minimums As the aircraft is descending for landing, minimums is the lowest altitude it can go before making a decision whether to continue with the landing or go around and try again.
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Missed approach procedure This is the set of steps pilots will take when they can’t land and need to go around and try again. This will involve climbing, turning and possibly “holding”, or waiting, if air traffic control tells them to do so.
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Monoplane This is an aircraft with a single pair of wings, as opposed to a biplane, which has two sets of wings.
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Nav fix Air navigation maps and computers contain thousands of routes and waypoints (or fixes) to help pilots and air traffic controllers keep track of where the aeroplanes are. An update can be sent from one aircraft to another providing latitude and longitude of a waypoint to correct the values of an aircraft’s inertial navigation system. A “fighter-to-fighter” data link can be used to send this update.
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Pattern (or landing pattern) This is the agreed shape to be flown by aeroplanes as they come in to land at an airstrip. It consists of a rectangular shape made up of 5 “legs”: departure, crosswind, downwind, base, and final. The pattern is flown at 1000 feet above ground level. Within about a mile of the runway, the pilot should enter the pattern on a 45 degree angle to the downwind leg, flying towards the approach end of the runway and parallel to it (see diagram). The pilot should then fly two 90 degrees turns, one towards the base leg and one towards the final leg as he descends to the touchdown point on the runway. There is an upwind leg parallel with the runway but located to the side opposite from the downwind. This is for emergency use if a pilot has to abort a landing.
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The standard traffic pattern is referred to as left traffic pattern where all turns are made to the left. A non-standard traffic pattern is with all turns to the right.
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Pitch attitude The attitude is the angle of pitch relative to the horizon.
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Pitch The angle of the aeroplane’s nose relative to the horizon. A positive pitching motion raises the nose of the aircraft and lowers the tail. The elevators are the primary control of pitch. See the diagram at the front of this A-Z.
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Pitot-static system A set of instruments which measure airspeed and Mach number, rate of climb and descent (vertical speed indicator) and altitude. The pitot-static system generally consists of a pitot tube, a static port, and the pitot-static instruments. If the pitot tube is blocked by ice, only the airspeed indicator is affected. It starts to register increase in airspeed when the aircraft climbs – although actual airspeed is constant – and a decrease in airspeed when the aircraft descends. A blocked static port, on the other hand, affects all pitot static instruments and is most commonly caused by airframe icing. It causes the altimeter and the vertical speed indicator to freeze at constant values. The airspeed is under-reported as the aircraft climbs and over-reported as the aircraft descends.
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Pitot tubes (see also Pitot-static system) An F-117 Nighthawk has four pitot tubes stationed around its nose that feed information into its flight control system. The information is vital to the aeroplane’s normal operation. While most aircraft’s pitot tubes are made from stainless steel and nickel, which reflect radar waves, the Nighthawk’s tubes are made of a special plastic, and are faceted, to reduce radar reflectivity.
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Precision approach radar This is used to provide horizontal and vertical guidance to position an aircraft as it approaches the runway. During the Second World War, controllers would guide aircraft down through cloud or darkness because the limited instrumentation in early aircraft meant pilots didn’t have this information available to them in the cockpit. It was called a ground-controlled approach (GCA). Nowadays, global navigation satellite systems (GNSS) are often used for precision approaches.
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Primary control surfaces These are the surfaces of an aeroplane which can be adjusted to control an aeroplane’s flight. They are the ailerons, the elevators and the rudder.
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Radar (radio detecting and ranging) Radar uses high frequency radio waves to track weather and to see other aircraft. Waves are beamed out like light from a torch; they reflect off objects and return to a receiver. The time taken for the beam to reach the object and return gives the object’s location. The radio waves travel at the speed of light (186,000 miles/second). An antenna doubles as a transmitter, sending out the waves, and as a receiver, listening for the waves coming back. It alternates between these two actions. Radar works in a similar way to radios but uses a different wave frequency.
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Radar reflectors Although the primary purpose of stealth technology is to reduce the radar cross-section by using materials and shapes that absorb or scatter radar, rather than reflecting it, there are situations when a stealth aircraft may want to be more visible to radar. Radar reflectors are then attached to the aircraft to give a greater radar signature and make her detectable.
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Radar return This refers to the radar waves that are reflected back to a transmitter. The time it takes for the radar waves to return and the size of the return provide information about the object’s distance, speed and size.
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Radome An Avro-Vulcan has a nose thimble radome which creates the bulge that is visible in the nose of the aircraft. It contains terrain-following radar and was fitted to most aircraft in the 1960s.
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Roll The tilt of an aeroplane from side to side. See the diagram at the front of this A-Z.
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Satellite terminal This is an additional section of an airport used in conjunction with the main terminal when an airport is operating at capacity to help manage passenger flow. It is often connected with the main terminal by a shuttle train or a walkway.
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Sick parrot Radio transponder technology was first designed during World War II when radar was being developed by the British. The ground transponder sent out a radio signal at one frequency prompting the transponder in the aeroplane receiving the signal to reply at a different frequency. This was a sort of password, indicating that it was friendly. If it returned the same signal as that one sent out, it was treated as “foe”. The system was called Identification Friend or Foe (IFF). When IFF was invented, code words were given to the procedure to hide its use from the German Luftwaffe. The aircraft’s transponder (the part that replies to the interrogation signal from the ground station) was called “parrot”. If an aircraft’s transponder stopped working and it was unable to use IFF, it would give a call stating it has a “sick parrot”. The noise a parrot makes is a “squawk” and this is the term used now for sending identification signals.
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Sniffer A little-known aspect of the Vulcan’s work from 1973-82 was strategic reconnaissance. This included hight-altitude missions using sniffer pods fitted under the wing to collect air samples. These would be analysed for radiation, revealing whether nuclear testing was being conducted.
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Sonic boom This is an explosive noise caused by the shock wave from an aircraft travelling faster than the speed of sound. This shock wave is created by the compression of air in front of the plane and then the sudden release of energy.
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Speed of sound This is 761.2 mph, referred to as Mach 1 and sometimes called “the sound barrier”. A supersonic aircraft is able to fly faster than the speed of sound.
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Speed tape This gets its name from its stickiness, which can keep the tape in place on an aeroplane at high speeds. Made from an aluminium pressure-sensitive material, it is used to perform minor repairs on an aeroplane’s fuselage or wings.
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Stall This happens when an aeroplane’s wings can no longer generate enough lift to maintain its height. A stall doesn’t mean the engine has stopped working, as it does with a car; it just means the plane has lost the necessary airflow over the wings to keep flying smoothly. The plane will begin to lose height rapidly. A stall often occurs when the plane’s angle of attack becomes too steep and the smooth flow of air over the wings is disrupted.
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Stealthy A stealthy aeroplane is designed to be as invisible as possible. This means minimising its radar cross-section through careful shaping of the airframe and using radar-absorbent materials. The F-117 Nighthawk was the world’s first operational stealth aircraft, produced in 1982.
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Stern The stern is the back or aft of an aeroplane, as opposed to the bow or foremost part, which is the front.
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Struts Biplanes have an upper wing running across the top of the fuselage and a lower wing below the fuselage. The wings and fuselage are connected with a series of wires called struts.
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Subsonic speeds Speeds below 761.2 mph, the speed of sound.
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Supersonic A supersonic aircraft is able to fly faster than the speed of sound, Mach 1, 761.2 mph. This is the speed that sound travels in air. It is sometimes called the sound barrier.
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Tail skid Instead of a tail wheel, early aircraft had a tail skid. As the Tiger Moth had no brakes, the tail skid was helpful in slowing the aeroplane down, particularly if it was taxiing on grass. The first Spitfires also had a tail skid rather than a tail wheel although it was soon replaced.
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Teddy bear run This is an event, often involving vehicles, which transports teddy bears for a charitable cause, to be donated to children in need. The event may be sponsored so that participants raise money for a charitable cause.
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Tenacity This is the quality of being determined, persistent and resilient in the face of difficulty.
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Thermae These were public bathhouses used in ancient Roman culture. The term is derived from the Greek word “thermos”, meaning hot, as these baths were often warm.
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Threshold markings These consist of longitudinal stripes on either side of the runway centreline (see diagram). There are often eight stripes but this varies and the number of stripes can be related to the runway width. A threshold marking helps identify the beginning of the runway.
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Throttle A throttle controls the flow of fuel or power to the engine.
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Touchdown zone and other runway markings (see diagram).
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Transonic cloud (also called a vapour cone) When an aircraft is travelling at close to the speed of sound (transonic air speed), it is travelling at almost the same speed as shock waves. These waves build up in front of the aeroplane to form a single, very large shock wave. The supersonic flow of waves causes an “expansion fan”, which decreases air pressure and therefore air temperature around the aeroplane to below the dew point at which water condenses. This water then appears as a cloud. Behind the aeroplane, the conditions are subsonic so there is a stern shock wave associated with a return to the slower flow of air. Severe instability can occur at transonic speeds due to the shock waves.
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Trimmed This means adjusted so that the control surfaces or alignment of the wings optimises aerodynamic performance for the required task.
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True altitude See Absolute altitude.
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Twenty-four-hour clock This is a way of measuring time that divides the day into 24 hours, instead of 12 hours before midday and 12 hours after midday. It counts the hours using midnight as 00.00. After midday at 12.00, it continues to 13.00 hours for 1 o’clock and 14.00 hours for 2 o’clock, and so on.
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Undercarriage This term is often used interchangeably with landing gear. However, landing gear refers specifically to the system of wheels, brakes, retractable mechanism, shock absorbers and components that support the aircraft during take-off, landing and taxiing. Undercarriage is a broader term that refers to the entire system that supports the landing gear, including the part of the aircraft that houses the landing gear when it is retracted.
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V1 This is the speed at which the pilot must decide whether he is going ahead with take-off. Before this speed, there is enough room left on the runway to stop the take-off. After this, there may not be.
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Vapour trail A vapour trail, condensation trail, or contrail is the stream of cloud visible behind an aeroplane. The hot, humid exhaust from jet engines mixes with the air, which is at a lower temperature and pressure, and this causes it to condense.
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Variable geometry wings These can be adjusted during flight to optimise performance under different conditions. When the wings are extended forwards, they create more lift and more drag. When they are swept back, this reduces drag, allowing the aircraft to achieve higher speeds. It also reduces the lift the wings provide. An F-14 Tomcat can sweep back its wings for the optimal angle given its speed.
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Visual flight rules (VFR) as opposed to instrument meteorological conditions (IMC). This is flight by visual reference assisted by limited basic instruments: the attitude indicator, airspeed indicator, altimeter, directional gyro, turn indicator, and vertical speed indicator. A pilot has entered IMC anytime they are unable to navigate or establish geographical position by visual reference to landmarks (unless they have planned and are legally able to operate “VFR on top”). If a pilot cannot maintain aircraft attitude control by reference to the natural horizon, they should assume they have entered IMC. Such situations must be accepted by the pilot as a genuine emergency, requiring immediate action.
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Visual reference flight See Visual flight rules.
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Waypoint A location defined by longitude and latitude co-ordinates as well as altitude which refers to a specific position in the sky. It is used to plot an aircraft’s flight path.
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Yaw A change in direction from left to right on a horizontal plane.