Copy of `Aeroplane Monthly - Airplanes glossary`

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Aeroplane Monthly - Airplanes glossary Category: Travel and Transportation > Airplanes Date & country: 14/12/2007, UK Words: 962

Flap
A hinged surface, usually at the trailing edge of a wing, used to increase the lift of a wing at slow speeds, to steepen the glide and to act as an air brake during the approach and landing.

Flap Angle
The angle between the chord of the wing and the chord of the flap. Flaps are often lowered about 5° to assist take-off and usually about 30° to 45° for landing.

Flare
(i) A pyrotechnic flare attached to the underside of the wing of an aeroplane to illuminate the ground for a night landing. Parachute flares are used to illuminate targets for night bombing.

Flarepath
A line of lights laid out on an aerodrome or surface of a harbour to act as a guide for aeroplanes taking off or alighting.

Flat Spin
A spin in which the tail of the aeroplane drops and the machine rotates in an almost horizontal plane. Recovery from a flat spin is difficult and sometimes impossible. Low-wing monoplanes are more prone to the flat spin than any other type of aeroplane so that an anti-spin parachute is usually carried on trials. This small parachute is attached to …

Flattening Out
In approaching to land an aeroplane, the transition from the gliding approach to the position to alight is termed 'flattening out.'

Fleet Air Arm
Descended from the Royal Naval Air service - which, with the Royal Flying Corps, became part of the Royal Air Force on April 1, 1918 - the Fleet Air Arm was formed in April 1924. It was then a part of the RAF, under the operational control of the Admiralty only when afloat. The Fleet Air Arm comprised all aircraft carried on ships of the Royal Navy…

Flettner Rotor
A cylinder rotated with forward motion to provide lift at right angles to its path. Flettner rotors have been used to provide lateral control in place of ailerons, without outstanding results.

Flick Roll
A rapidly executed roll in a horizontal plane in which the aeroplane is turned completely around its longitudinal axis by use of both rudder and elevators and continues in level flight. A flick roll is in reality a horizontal spin and the aeroplane is temporarily out of control during its course. The flick roll was first demonstrated on a Bristol S…

Flight
(a) The act of flying.

Flight Engineer
A member of the crew of a large aeroplane who controls the engines in the air, thus relieving the pilot of an onerous duty.

Flight Lieutenant
A commissioned rank in the Royal Air Force equivalent to Lieutenant in the Royal Navy and Captain in the British Army. The rank may be distinguished by two sleeve stripes and two stripes on the coat shoulder straps.

Flight Sergeant
A non-commissioned rank in the Royal Air Force which corresponds with Chief Petty Officer in the Royal Navy and Colour Sergeant, Chief Quarter Master Sergeant, etc in the British Army. The pay of a Flight Sergeant in 1942 varied from 7s 9d per day to 12s per day on ground duties up to 15s 6d per day for a Flight Sergeant Pilot or Flight Sergeant Ob…

Flightpath
The path of the centre of gravity of an aeroplane relative to the air. If the aeroplane is climbing steeply or gliding flatly the flightpath may be at an angle less acute than the attitude of the longitudinal axis of the machine.

Flightway
A specified air space beyond the end of a runway of an aerodrome. Obstructions must be kept below the specified heights in the flightways.

Float
(a) When approaching to alight, the distance travelled horizontally in the air after flattening out and before touching down. The better streamlined the aeroplane the greater its float, unless fitted with flaps. Flaps act as air brakes and shorten the float and they make possible landing in a smaller space.

Float Seaplane
A seaplane provided with floats (American pontoons) as its means of buoyancy on the water.

Floating Ailerons
Ailerons so connected that they remain free, while the control column is centralised, to preserve a negative angle of attack in relation to the air flow whatever the angle of the mainplane.

Floodlight
Wide angle lights used on an aerodrome to illuminate all or part of the landing area at night.

Flotation Gear
Emergency flotation equipment installed in landplanes liable to fly over the sea to give them buoyancy should they be forced down on the water. Flotation gear usually consists of watertight bags or compartments in the fuselage.

Flutter
Usually applied to wings or ailerons - the unstable oscillation caused by interaction between aerodynamic forces, elastic reactions in the structure and the force of inertia. Unless damped quickly flutter will break a wing. The cure is usually to dispose the weights so that the centre of gravity of the wing is as far forward as possible. Ailerons, …

Flutter Speed
The lowest airspeed at which flutter occurs in a given aeroplane.

Flying Blind
Flying solely by instruments in thick cloud or darkness.

Flying Clubs
The Flying Club movement began with the advent of the light aeroplane in 1924. The Clubs received a Government subsidy up to the outbreak of World War Two which made possible the training of pupils - particularly the Civil Air Guard - at reasonable rates.

Flying Controls
The mechanism whereby the pilot operates the control surfaces from the control column.

Flying Machine
A power-driven heavier-than-air craft. Includes all aeroplanes, helicopters and gyroplanes, but not gliders, sailplanes or airships.

Flying Officer
A junior commissioned rank in the RAF corresponding to a Sub-Lieutenant in the Royal Navy and a Lieutenant in the British Army.

Flying Position
The attitude of an aeroplane when it is flying straight and level.

Flying Speed
Maximum: The maximum airspeed of an aeroplane when flying level in Standard Atmosphere. Mimimum: The minimum airspeed at which an aeroplane can fly level in Standard Atmosphere.

Flying Wires
Those bracing wires in a biplane which transfer the lift of the wings to the main structure. Also known as 'lift wires.' They extend diagonally outwards and upwards. Anti-lift wires which take the weight of the wings on the ground extend outwards and downwards.

Flying-boat (Boat Seaplane)
A seaplane in which the main body or hull provides the means of support on the water.

Fog
A condition of bad visibility in the lower atmosphere caused by the presence of particles of condensed moisture, of smoke, or of a mixture of the two held in suspension in the air.

Folding Wings
The mainplanes of an aeroplane designed to fold so that it may be stored in a confined space.

Force
That which produces or tends to produce a change of motion or shape of a body. Measured in pounds or dynes.

Forced Landing
The unpremeditated landing of an aeroplane usually caused by mechanical breakdown or bad weather.

Forecast
A statement of weather to be expected over a given area or route during a definite period.

Four-stroke engine
An internal-combustion engine in which explosion of the mixture in each cylinder occurs at every alternate revolution of the crankshaft. Nearly all aero-engines work on the four-stroke cycle at present.

Fracto-cumulus
Small cumulus clouds with ragged tops which continually change their form.

Fracto-nimbus
Low, dark, ragged clouds associated with bad weather.

Fracto-stratus
Layer cloud broken into irregular, ragged fragments.

FRAeS
Fellow of the Royal Aeronautical Society.

Free Balloon
A balloon intended for cross-country flying carried by the wind.

Freeboard
In a flying-boat hull, the vertical distance from the loaded waterline to the lowest opening through which water could enter the hull or to the level of the top decking if there is no opening below its level.

Frise Ailerons
Ailerons with their hinges a little back from their leading edges and so shaped that when the aileron is raised a horn projects into the airflow below the wing, thus creating turbulence and destroying lift. Their function is to equalise aileron drag in a banked turn. Named after Mr Frise, Chief Designer to the Bristol Aeroplane Co Ltd who invented …

FRMetSoc
Fellow of the Royal Meteorological Society.

Front
A line of discontinuity between cold and warm masses of air.

Frost
A condition in which the temperature of the air is below the freezing point of water.

Froude's Law
A law used in Hydrodynamic calculations to convert the full size data obtained with scale models in testing tanks. It states that to get similar flow on model and full scale, the model should be towed at a speed equal to the full-scale speed multiplied by the square root of the scale of the model.

Fuel Tank
A tank containing the fuel supply for an aero-engine.

Fuel-contents Gauge
A gauge for indicating the contents of a fuel tank ie full or empty etc.

Fuel-flow Meter
An instrument for indicating the rate of flow of fuel.

Fuel-jettison Gear
Gear to enable part of an aeroplane's fuel load to be discharged in case of emergency. This is particularly important with modern aeroplanes because of the high wing-loadings at take-off in general use - loadings too great for safe landing if one should become necessary soon after take-off.

Fuels
Aero-engine fuels are either refined from crude petroleum or obtained from coal, the latter source being that on which Germany has had largely to depend.

Fuselage
The main body of a landplane, float seaplane, or float amphibian, providing accommodation for the crew and useful load.

Gale
A wind of 'Force 8' or above on the Beaufort Scale of Wind Force defined as strong enough to 'break twigs off trees and generally impede progress'.

Gap
The distance separating the mainplanes of a biplane, triplane or quadruplane.

GAPAN
The Guild of Air Pilots and Air Navigators of the British Empire.

Gas Bag
A gas container in a rigid airship. Rigid airships are provided with a large number of gas bags (usually about 16) which hold the supporting gas and are anchored within the rigid framework.

Geared Engine
An engine in which the power developed on the crankshaft is transmitted to the propeller shaft through a reduction gear. The vast majority of large aero-engines are of this type, although in the smaller classes direct-drive engines are still widely used. A geared engine makes possible a slower-moving bigger propeller of higher efficiency.

General Inference
A general description of the meteorological situation at a given time deducted from the pressure distribution shown on a synoptic weather chart, together with the changes in progress and a statement of the kind of weather likely to be experienced over a particular area as a result of these changes.

Geodetic Structure
A structure built up of geodetic members, that is to say, of members which have the shape of the shortest (surface) distance between two points on a curved surface.

Geometric Pitch
The distance which an element of a propeller would advance in one revolution under conditions of no slip.

Gibli
A hot dry southerly wind in Tripoli, similar to the Sirocco.

Glacier Breeze
A cold breeze, blowing down the course of a glacier, owing its origin to the cooling of the air in contact with the ice.

Glazed Frost
A layer of smooth ice formed by rain falling on exposed objects when air temperature is below freezing point.

Glide
The gradual descent of an aeroplane with gravity alone providing the motive power.

Glider
A fixed-wing aerodyne intended for motorless flight. Gliders are generally divided into four classes:

Gliding Angle
The angle between the path of flight of an aeroplane and the horizontal while gliding.

Gliding Certificates
There are five classes of Gliding Certificate: 'A', 'B', 'C', 'Silver C' and 'Gold C.' Some 1,639 people had been awarded certificates in England up to the time when gliding was stopped by World War Two.

Gnomonic Projection
A method of projecting a map used for charts of the Polar regions and for harbour surveys. The Gnomonic projection produces a map on which direct measurements are accurate only over short distances. It assumes that each subdivision of the surface of the earth is flat. The Great Circle then appears as a straight line. Its advantages are that for sma…

Gordon Bennett Balloon Race
The first classic air race, held between 1906 and 1938. Free balloons were wafted from a joint starting place by the wind and the one to go farthest won. The record distance was 1,368 miles, set up by France in 1912 - one of the few air records standing for so long.

Gore
A fabric segment of a parachute, airship or balloon.

Gosport Tube
A system of voice pipes and headphones widely used in training aircraft for communication between instructor and pupil. The name comes from the fact that it was first used at the Special School of Flying, Gosport, under Smith-Barry in 1916. Sometimes called 'de Havilland 'phones.'

Gradient Wind
A wind induced in a certain direction by flow of air balancing the pressure gradient caused by the earth's rotation and centrifugal force.

Gravity
The force exerted on a body by the mass of the earth. It is equal to the 'weight' of the body in pounds. The speed of a falling body under the action of gravity depends in practice on its density; that is, on the relation between its weight and the area it presents to air resistance. In a vacuum, the rate of descent of any body increases at the rat…

Gravity Tank
A fuel tank so situated that the contents flow to the engine by gravity alone.

Great Circle
The line over the surface of the earth in the shortest curved path. It is, in fact, the shortest line joining two points on the earth's surface.

Gregale
(pronounced 'gregahley'). A strong wind from the North-East usually in Winter, in the Ionian Sea and neighbouring parts of the Central Mediterranean.

Grid Deviation
The angle between a grid line and True North.

Gross Weight
The maximum weight at which an aeroplane is permitted to fly. This is stated on the certificate of airworthiness for a civil aeroplane.

Ground Engineer
A person licensed to certify the safety for flight of an aeroplane or its engine or to inspect and improve repairs, replacements and overhauls to aeroplanes or aero-engines.

Ground Speed
The speed of an aeroplane relative to the earth's surface, as distinct from its speed through the air. Thus if an aeroplane is flying at 200 m.p.h. through the air and is flying against a steady wind of 20 m.p.h. its ground speed will be 180 m.p.h.

Ground Strafing
A term given to low-flying gun attacks on ground targets.

Groundloop
An involuntary, uncontrolled and usually sudden circular turn when moving on the ground, caused by directional instability. Groundlooping can afflict tailwheel aircraft (as distinct from tricycle-undercarriage aircraft) on take-off or landing, and if it happens at high speed the undercarriage may collapse.

Group
The RAF formation into which the Commands are divided. The Group, in turn, is subdivided into Wings and the Wings into Squadrons.

Group Captain
A commissioned rank in the RAF equivalent to that of Captain in the Royal Navy and Colonel in the British Army.

Gust
A sudden local fluctuation in velocity of the wind.

Gyroplane
A mechanically-driven aeroplane deriving its lift from the reaction of the air on one or more rotors freely rotating in a horizontal plane. This type of aircraft, of which the Autogiro is one example, should be clearly distinguished from the helicopter, in which the rotors are power-driven in normal flight.

Haar
A local name in Eastern Scotland for a sea fog which spreads inland.

Haboob
A disturbance of the line squall type which occurs in the Sudan during the rainy season and is usually accompanied by a dense sandstorm.

Hail
Precipitation in the form of hard pellets of ice which fall from cumulo-nimbus clouds and are often associated with thunderstorms.

Hand Starter
A mechanism for the rotation by hand of an aero-engine's crankshaft for starting.

Hangar
A building to house aircraft. This was originally a French term which came into use in this country before the Second World War.

Harmattan
A very dry North-East wind prevalent in West Africa during the dry season (November to March) carrying with it great quantities of dust from the Sahara.

Haze
Slight fog caused by the presence of solid matter such as dust, smoke, or hydroscopic particles carrying a deposit of water in air not saturated with water vapour.

Head Resistance
More correctly 'drag.' The total resistance of an aeroplane to forward motion along its line of flight.

Header Tank
A tank in the cooling circuit of liquid-cooled aero-engines in which coolant is received from the engine and distributed to the cooling elements of the radiator.

Heap Clouds
Clouds with vertical structure and usually found between 1,500ft and 20,000ft. They are:

Heavier-than-air Craft.
More correctly 'aerodyne.' Includes all aeroplanes, gliders, gyroplanes and helicopters.

Height Computer
A calculating device for converting indicated to true height by taking the density factor into consideration.