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

Nurse Balloon
A fabric container used either as a gas reservoir or to maintain a constant pressure in an aerostat's envelope on the ground.

Observation Mirror
An engraved mirror used for bombing training in the same way as a camera obscura. The bomber flies over the mirror, which is suitably mounted on the ground. A light is flashed in the aeroplane at the release point of the bomb and this is plotted on the mirror. In this way the accuracy of the 'bombing' can be determined.

Obstruction Angle
The angle between the horizontal and a line joining the highest obstruction in the approaches to an aerodrome to the nearest point of the appropriate runway.

Obstruction Light
A light indicating the presence of an object which is dangerous to an aircraft in flight.

Obturator Ring
An L-section ring fitted round a piston to maintain a gas-tight seal between the piston and the cylinder wall.

Occlusion
A meteorological term for the 'front' (that is, junction between masses of warm and cold air) which remains after a cold front has met a warm front and the latter has been forced upwards.

Occulting Light
A flashing light in which the light period is distinctly longer than the dark period.

Octane Number
The quality of a fuel to produce power in a high-performance aero-engine without pre-ignition through high compression. The higher the octane number the greater the power that can be taken from the fuel, provided that the engine is designed to take advantage of it. The present highest octane number in use is 100. In peacetime ordinary motor fuel wa…

Omni-directional Beacon
A ground radio transmitter which is non-directional and is used for navigational purposes by aeroplanes with direction finders. The aeroplane's radio operator recognises the beacon from its code signal and then finds its bearing from the aeroplane with his directional receiver.

Open-jet Wind Tunnel
A wind tunnel in which the air stream passing the body under test is not enclosed, but is in the form of a free jet rather like water squirting from a hose.

Opposed-piston Engine
An engine in which the compression is effected by two pistons in the same cylinder acting in opposition. The Junkers Jumo 205 C.1. aero-engine works on this principle.

Optimum Angle
(1) The gliding angle at which the least height is lost in proportion to the ground covered. (2) The angle of attack of an aerofoil at which the ratio of lift to drag is greatest.

Ornithopter
A mechanically driven aerodyne whose lift in flight is obtained by the action of flapping wings.

Orographic Rain
Rain caused by rising ground in the path of moisture-laden wind.

Oswald Watt Gold Plaque
A gold medal presented by the late Colonel W. Oswald Watt for yearly award to the airman who performed the most outstanding performance during the year in the Commonwealth of Australia, or to the Australian-born airman who performs the most brilliant feat outside Australia. The plaque was first awarded in 1921 to F.S. Briggs.

Outer Area
A circular zone round an airport within which the obstructions must not be above a certain height.

Outer Cover
The external covering of the hull of a rigid airship.

Outer Marker-beacon
A radio beacon comprising part of a blind approach installation which defines a predetermined distance from the aerodrome boundary. As the aeroplane passes over the beacon in its approach its position is signalled to the pilot by the sound of a buzzer or the flash of a lamp on the instrument panel.

Outflow
The increase in air velocity behind an airscrew produced by its rotation.

Overhang
(1) The extent to which the wingtip of one or two superimposed planes projects beyond the tip of the other. (2) The distance from the outer point of support to the tip of an aerofoil.

Overstrain
The condition of a structural material which has been stressed past the yield point. Materials can be annealed - given a form of heat treatment - to remove the effects of overstrain.

Oxidation
The action of combining any substance with oxygen. Oxidation may be rapid, as in an explosion; of moderate speed, as in the burning of solid fuels; or slow, as in the rusting of metals.

Oxygen Equipment
Oxygen equipment is provided in all modern Service aircraft. The installation includes cylinders containing oxygen under pressure, regulators to control the supply pressure, flow meters and a breathing mask for each member of the crew.

Oxygen-mask Microphone
A microphone for radio transmission and intercommunication between aircrew members fitted to an oxygen breathing mask

Pack
The canopy and shroud lines of a parachute packed within the pack cover.

Pack cover
A canvas covering which accommodates a parachute when folded.

Packing
The operation of folding a parachute and inserting it within the pack cover ready for use. Parachute packing is done by qualified specialists.

Pampero (pronounced "pampearaw")
Line squalls experienced in Argentina and Uruguay which are accompanied by rain, thunder and lightning, and a sudden change of wind to the South-West.

Pancaking
Landing an aeroplane in a stalled condition so that it has an abnormally high rate of descent or an abnormally low forward speed.

Panel
A section of a parachute canopy or gasbag.

Parachute
A collapsible device used to retard the descent of a falling body. Parachutes, which comprise a pack, a canopy, shroud lines and harness, may be of two basic types:-

Parachute Flare
A pyrotechnic flare attached to a parachute, which can be dropped from an aeroplane to illuminate the ground beneath it.

Parachute Troops
The parachute soldier was much in the news during the Second World War and with other types of airborne troops - carried in both aeroplanes and towed gliders - was considered to be of growing importance in the future. The Russians started training parachute troops in 1934, and were later copied by the Germans. British parachute units were formed in…

Parachutist
A person using a parachute.

Parasitic Drag
The total drag of an aeroplane or glider less the drag which results from the lift of the wings. Sometimes called 'non-induced drag.'

Parasol Monoplane
A monoplane with the mainplane mounted above the fuselage on struts.

Parkerising
A process whereby a protective coating is applied to iron and steel parts to prevent rusting and corrosion.

Partially Evaporative Cooling
A cooling system for aero-engines in which the coolant (cooling liquid) is allowed to boil during part of its passage round the cooling circuit.

Patch
A piece of fabric sewn to the envelope of a balloon or non-rigid airship, to which the rigging lines are attached.

Payload
That part of the useful load of a civil aeroplane which can be devoted to paying load; that is, the weight of passengers, mails and freight that may be carried.

Performance
The essential flying characteristics of aircraft under standard atmospheric conditions. The figures obtained under any existing conditions are corrected so as to apply to a standardised theoretical state of the atmosphere.

Petrol
A trade name for the spirit consisting of a mixture of volatile fractions of the paraffin, napthene and aromatic series of hydrocarbons used in internal-combustion engines.

Phillips Entry
The form of dipping leading edge to a wing section which was patented in 1884 by Horatio Phillips, one of the British pioneers of heavier-than-air flight.

Pilot
The individual who operates the flying controls of aircraft.

Pilot Balloon
A small free balloon used to determine the direction and speed of the wind at various heights. The position of the balloon after given intervals of time is observed with a special type of theodolite. From the figures obtained in this way the speed of the wind at successive heights can be calculated.

Pilot Officer
A junior commissioned rank in the RAF corresponding to a Midshipman in the Navy and a Second Lieutenant in the Army.

Pilot Parachute
A small parachute connected to the main canopy of many types of free parachute to ensure its rapid and correct withdrawal from the pack cover.

Pilotage
The art of piloting aircraft safely and accurately from one place to another by means of map-reading and the recognition of ground objects.

Piston
A cup-shaped member of circular cross-section which slides up and down in the cylinder of an engine. It absorbs the expansion force of the fuel in the cylinder and transmits it via the connecting rod to the crankshaft.

Piston Ring
A ring inset into the piston of an engine intended to preserve a gas-tight seal between the piston and the cylinder wall.

Pitch
(i) The geometric pitch of a propeller is the distance that propeller would advance in one revolution provided there was no slip.

Pitch Indicator
An instrument for indicating angle of pitch of an aeroplane in flight. Sometimes called a fore-and-aft level.

Pitching
The rotary motion of an aircraft about its lateral axis. That is to say, a motion in which its nose tends to rise or fall.

Pithio
A high carbon steel used for valve ends and similar parts of an aero-engine.

Pitot Tube
Parts of an airspeed indicator consisting of a tube with an open end exposed to the airstream. The compressed air in the pitot tube is conveyed by a length of tubing to the pilot's cockpit. There the pressure is shown by the airspeed indicator, which gives a reading in terms of miles an hour airspeed.

Plane
The complete wing of an aeroplane or glider. The term 'plane' should not be used for 'aeroplane.'

Planing Bottom
A smooth surface on the underside of the hull of a flying-boat or of a float lying forward of the main step.

Polar Front
A meteorological term for the line of discontinuity which occurs under certain conditions between a mass of air coming from polar regions and another mass from more temperate zones.

Porpoising
The undulating motion in a fore-and-aft direction of a seaplane when taxying. It is a sign of bad hull design and was a common characteristic of early seaplanes.

Port
The left side (looking forward) of aircraft and ships. The port navigation light is red in colour.

Port Drift-angle
A navigational term for the angle between the true course and the true track when the bearing of the former is greater than that of the latter.

Position Error
The reading of an airspeed indicator differs from the true airspeed because of a number of errors. The error arising from the mounting of the pitot tube in a position where the airflow is disturbed by its proximity to the aeroplane is termed the 'position error.'

Pour le Mérite
An obsolete German decoration for military bravery which at one time ranked highest and was approximately equivalent to our own Victoria Cross, although it was more freely awarded. Most of the outstanding German fighter pilots of the First World War gained the Pour le Mérite. Its French name was derived from the fact that it was instituted by Frede…

Power
The time-rate of expended energy when work is done.

Power Jet
(i) A fuel jet in the carburettor of an aero-engine which comes into operation when the throttle is opened beyond the setting for maximum cruising conditions. (ii) A device for propulsion of aircraft as used by the Caproni-Campini C.C.2 jet-propulsion aeroplane.

Power Loading
The ratio of maximum loaded weight of an aeroplane to its total maximum power. That is to say, Power loading = loaded weight total power.

Pre-ignition
The ignition of the charge in the cylinder of an internal-combustion engine before it is fired by the sparking plug(s). Pre-ignition is caused by some overheated part, such as the sparking plug or exhaust valve or by incandescent carbon.

Precipitation
A general meteorological term for the forms in which water may fall after condensation from the atmosphere. Precipitation may take the form of rain, drizzle, snow or sleet.

Precipitation Interference
Disturbance in radio reception caused by the impact of rain, snow, hail or sleet on the aerials of an aircraft in flight.

Pressure Gradient
The rate of change of pressure in an imaginary horizontal plane running between areas of high and low pressure on a weather map.

Pressure Head
A combination of pitot and static pressure tubes forming part of airspeed indicator installation.

Primer
A device for spraying fuel into the induction system or combustion chambers of an aero-engine to facilitate starting.

Profile Drag
The drag (that is to say total head resistance) of the wings of an aeroplane or glider excluding that caused by the vortices at the wing tips. In other words, profile drag is the sum of the drag caused by surface friction and the pressure drag.

Profile Drag Power Loss
The power expended in overcoming the profile drag of the blades of a propeller.

Projection
Geographically, a method whereby the outlines of features on the surface of the world may be represented on a map. As the world is spherical whereas the map is flat, the outlines on maps are only approximations to the true outlines on the world itself. Well-known projections include Mercator's, Cassini's Gnomonic, and Gauss Conformal.

Proof Stress
The load for a given cross sectional area under which a material must not stretch permanently beyond a specified percentage of its length.

Proofing
The treatment of fabric to render it gas-tight or water-resisting.

Propaganda Balloon
A small free balloon, sent up without passengers but with a device by which propaganda leaflets may be dropped at intervals. Propaganda balloons were suggested in the mid-19th Century and were used is the First World War. They were also employed to a small extent by the French during the early months of the Second World War.

Propeller
A device commonly used to convert the power of an aircraft piston or turboprop engine into propulsive force; each blade is essentially a rotating wing, twisted and varying in section from root to tip to achieve maximum efficiency, which produces lift in a forward direction, i.e. thrust. In the 1940s propellers were often referred to as airscrews.

Prototype
The first trial aeroplane built to a new design.

psa
Graduate of the RAF Staff College.

Pterodactyl
The name of a series of tailless aeroplanes designed by Captain G.T.R. Hill and built by Westland Aircraft Ltd. Captain Hill was aided in the design work by Major J.W. Dunne, the famous pioneer of this type of aeroplane.

Purity
Of the gas in an aerostat, the ratio of the volume of hydrogen or helium (depending on which is used) in the envelope to the total volume of gas contained.

Pusher Aeroplane
An aeroplane with pusher engine(s).

Pusher Engine
An aero-engine which drives a pusher propeller, that is to say, which propels the aeroplane forward by means of a propeller situated aft of the wing.

Pylon
The support or mast for the rotors of a gyroplane or helicopter. Pylons are also occasionally used to brace, from above, the wings of a wire-braced monoplane or to protect the pilot from injury in a crash should the aeroplane overturn.

Qibli (pronounced "kibly")
A hot, dry, southerly wind experienced in Tripoli.

Quadruplane
An aeroplane with four mainplanes mounted one above another

Radial Engine
An aero-engine with its cylinders arranged radially around the crankshaft, the cylinders being stationary and the crankshaft revolving.

Radiator
In an aeroplane, a device which disposes of the surplus heat of a liquid-cooled aero-engine by employing a liquid, known as the coolant, to convey the heat from the cylinders to the radiator. The latter transfers the heat from the coolant to the atmosphere.

Radio Telephony
Usually abbreviated to R/T to distinguish from W/T - wireless telegraphy. The transmission by radio of the human voice. This method of communication is in general use for short range work between aeroplanes in flight and between aeroplanes and ground stations.

Radius of Action
Half the range of an aeroplane in still air.

Rain
A precipitation from clouds taking the form of drops of water.

Rain Gauge
An instrument to measure rainfall.

Range
The maximum distance an aeroplane can travel in level flight under Standard Atmosphere Conditions without refuelling.

Rate of Climb Indicator
An aeroplane instrument which shows the rate at which a change of height is taking place.

Recalescence Point
The point on the cooling curve of a steel where carbides are precipitated.

Receiver
That portion of a wireless apparatus which receives the signals through the ether waves and modulates them.

Reconnaissance
Exploration from aircraft of the whole area in the occupation of the enemy, from the front line outposts to the back areas; in other words, all the centres where his war effort operates.

Records
All records achieved in aviation must be certified by the Fédération Aéronautique Internationale, the controlling authority of air sport as recognised by the principal countries of the World.