Glossary Of Early Aviation and Flying Terms

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	A Glossary of early aviation and flying terms circa 1918.
	This glossary of terms is representative of the terminology which a suitably trained service of civilian pilot would be expected to be familiar with circa 1918. Many of the definitions are still valid today and help demonstrate the speed of development of aviation and training methods given the relatively short period of time that powered controlled flight had been a reality.
	Term	Definition
		A
	Aerobatics	Aerial manoeuvre stunts.
	Aeroplane	A heavier-than-air flying machine, supported by the action of air on fixed planes.
	Ailerons	Hinged flaps let into the extremities of the main planes and operated by the control lever, to bank the machine and also to maintain its lateral level.
	Ailerons Balanced	By connecting the ailerons of each wing, so that when one is pulled down and the other is pulled up the surfaces are made to balance.
	Airbrake	A flap that can be let down so as to increase the resistance of the machine to the air.
	Air Pocket	See " Pocket."
	Air Speed	The speed of the machine through the air.
	Air Speed Indicator	An instrument for registering the speed of the machine through the air.
	Altimeter	An instrument for indicating the height of the machine from the ground where it started from.
	Angle of Incidence	See "Incidence."
	Aspect Ratio	The proportion of span to chord of a plane.
		B
	Back	A change of wind in an anti-clockwise direction, i.e., from E. to N.
	Backwash	The disturbed air in the wake of a machine in Right
	Balloon To	The upward glide of a machine near the ground caused by the pilot descending too fast and pulling the control lever back too much or too quickly.
	Bank To	To raise one wing for the purpose of turning.
	Bay	The space enclosed by two struts and their upper and lower adjoining surfaces.
	Belt	The safety strap which secures the pilot to his seat.
	Bessoneau	A tent for storing aeroplanes which can be erected and dismantled in a few days.
	Biplane	An aeroplane with two pairs of wings set one above the other.
	Blimp	Slang Term referring to small airships
	Blip To	To switch on and off rapidly.
	Body	That part of a machine which accommodates the engine, pilot, passenger and probably the petrol and oil tanks.
	Boom	See "Tail Boom"
	Boss of a Propeller	The centre portion by which it is attached to the engine.
	Bounce	The upward and forward movement of a machine which has struck the ground without flattening out sufficiently.
	Brevet	A certificate showing that a pilot has passed certain elementary flying tests and may be considered a qualified pilot.
	Bumps	Disturbances or roughness in the air due either to changes of temperature, clouds or wind.
		C
	Cabana	The projecting arrangement of struts above the pilot's head on a monoplane to which the anti-lift wires are attached.
	Cabre	Tail down.
	Camber	The maximum depth of curvature of the upper and lower surfaces of a wing.
	Cartwheel	particular type of aerial manouvre.
	Cell	The whole of the lower surface of a plane and the whole of the top surface of the plane above it, with the struts and wires holding them together.
	Cellule	The box-like rectangular compartments in a biplane formed by the upper and lower planes and the interplane struts.
	Centre of Gravity	Centre of weight
	Centre of Pressure	A line running from wing tip to wing tip, through which all the air forces on the wing may be said to act.
	Centre Section	The centre cellule of a biplane where this cellule is made detachable from the wings.
	Chocks	Wooden blocks placed in front of the wheels of a machine to prevent it moving when the engine is started.
	Chord of a Wing	The distance between the leading and trailing edge of a wing.
	Cockpit	The pilot's seat.
	Cold Feet	A complaint, otherwise known as aerosthenia or nervousness of going into the air.
	Combustion Chamber	The space between the top of the piston and the cylinder where the explosion of the mixture takes place.
	Compression	The upward stroke of the piston which compresses the mixture in the combustion chamber.
	Conk	The engine is said to "conk " when it fails.
	Contact	Word used to denote that the switch is on.
	Control Lever	Generally known as the " joy stick " or stick. A vertical lever controlling the fore-and-aft and lateral movements of the machine.
	Control Wires	Wires connecting the rudder bar and control lever with their respective con-trolling surfaces.
	Cowl	A sheet-metal cover generally fitted over or round the engine.
	Crash Helmet	A specially-made flying helmet designed to save the pilot's head in case of a crash.
	Crash To	To smash the machine.
		D
	Dihedral Angle	A machine is said to possess a dihedral angle when the wings rise upward from the centre of the machine.
	Dive	To descend steeply.
	Dope	A preparation used to paint the wings in order to render them taut and weatherproof.
	Dope Can	A metal syringe containing petrol for priming the engine.
	Drift	The crabwise motion of a machine over the ground due to a side wind ; also used to denote head resistance.
	Dual Control	A system of levers and controls for the engine and machine, so that either the pilot or passenger can operate them.
		E
	Elevator	A hinged controlling surface, or flap, operated by the fore-and-aft movement of the control lever. Always set parallel with the wings of the machine and generally behind them. Used to control the up-and-down motion of the machine and in steep banks to make the machine turn.
	Empenage	The tail unit of a machine, consisting of rudder, elevator and fixed tail plane.
	Engine Bearer	The metal framework or tubing to which the engine is fixed.
	Exhaust	The upward stroke of the piston which drives the burnt and exhaust gas out of the combustion chamber.
	Explosion	The power stroke of the engine.
	Extensions	Additional lifting surfaces added to the top planes.
		F
	Factor of Safety	Obtained by dividing the stress at which a body will collapse by the maximum stress it will be called upon to bear.
	Fin	A fixed vertical plane generally fitted in front of the rudder to increase the stability of the machine.
	Flares Ground	Waste soaked in petrol, or petrol in buckets, set on fire and used as a landing light for night flying.
	Flares Parachute	Magnesium light electrically fired and attached to a parachute, which is re-leased near the ground to facilitate landing at night.
	Flares Wing Tip	Magnesium lights electrically fired and used to facilitate landing at night.
	Flattening Out	A phrase used to describe the gradual decreasing of the gliding angle of a machine until it merges into the horizontal a few inches off the ground.
	Flight A	An organization consisting of a small group of machines.
	Flying Speed	The speed of a machine through the air necessary to maintain its support.
	Forced Landing	See "Landing."
	Formation Flying	The practice of a group of machines keeping station in the air.
	Fuselage	The body of a tractor machine.
		G
	Gap	The distance between the upper and lcwer wings of a biplane.
	Gas Bag	lang term for airships.
	Glide	To descend with the engine cut off with the machine under control and at approximately the flying level speed.
	Gliding Angle	The angle that the fore-and-aft line of the machine makes with the horizon in cider to make a correct gliding descent..
	Ground Speed	The speed of the machine relative to the ground, which may be equal to, greater, or less than the air speed ; therefore, ground speed is equal to air speed + or - wind speed.
		H
	Hangar	An aeroplane shed.
	Hate To Commit	To be extreme in doing a thing, i.e., excessive stunting near the ground.
	Heavy Handed	Refers to a pilot who is clumsy with his controls and inclined to over-correct.
	Height Indicator	See "Altimeter."
	Hoik To	To make the machine climb steeply and suddenly.
	Horizon	The limit of ground in view.
	Hun	Slang term for a person learning to fly.
		I
	Incidence Angle of	The angle that the chord' of a wing makes with the direction of motion relative to the air. A particularly muddling term, as it is often measured as the distance in inches that the front spar is above the rear spar when the machine is in the flying-level position.
	Inclinometer	An instrument for showing the angle of the machine relative to the ground.
	Induction	The inlet stroke of the engine.
		J
	Joy Stick	See " Control Lever."
		K
	Kathedral Angle	A machine is said to possess a kathedral angle when the wings slope downwards. from the centre of the machine.
	Keel Surface	The side surface of a machine as opposed to the head-on surface.
	King Post	A bracing strut generally found on the top of controlling surfaces, such as rudder, ailerons and elevator, in which case it also acts as a lever.
	Knock	A peculiar noise emanating from the engine and indicating some kind of mechanical trouble.
	Knot	A nautical mile per hour, i.e., it is wrong to speak of knots per hour.
		L
	Landing	The action of a machine in coming to earth.
	Landing Forced	The action of a machine in coming to earth other than at the will of the pilot, i e., in the case of the engine failing.
	Leading Edge	The point or entering position of a wing.
	Leeward	Away from the wind.
	Leeway	Lateral drift to leeward.
	Left and Right	Always refer to the left and right of the machine and engine as seen by the pilot sitting in his seat.
	Lift	The force exerted by the air on a plane in a. direction perpendicular, or nearly so, to the motion.
	Log Book	A book kept by pilots giving details of each flight.
	Longerons	The longitudinal members of the fusel-age.
	Loop	A manoeuvre in which the machine, after flying straight, does an upward and backward turn or circle, and then continues in the same direction as before.
	Lubber Line or Lubbers Point	A mark on the body of a compass corresponding with the fore and aft line of the machine.
		M
	Machine	The aeroplane as apart from the engine.
	Motor	An incorrect term for the power unit or engine.
	M.P.H.	Miles per hour.
		N
	Nacelle	The body of a pusher machine.
	Nose	The front part of a machine.
	Nose Dive	A very steep descent with or without engine.
	Nose Heavy	Backward pressure required on the control lever to make the machine fly level.
	Nose Piece	The front central portion of a rotary engine.
		O
	Outrigger	The framework connecting an elevator placed in front of the machine with the main planes.
		P
	Pancake	To drop to earth from a height of a few feet owing to losing flying speed and flattening out too soon.
	Pegging Down	Securing a machine by rope to pegs in the ground so as to prevent it capsizing in a wind.
	Pilot	A person controlling an aeroplane in the air.
	Pitch of a Propeller	The forward distance that the propeller would travel if it were allowed to cut its way, without slip, through some medium such as butter.
	Pitot Tube	Consists of two tubes, one open to the air flow and the other protected. The other ends of the two tubes are connected to the air-speed indicator. One tube is called the pressure tube and the other the suction, or static, tube.
	Plane	Term used to apply to the supporting surfaces of a flying machine. The planes may be cambered, as in the case of the wings, or flat, as in the case of the tail plane.
	Plane Main	The wings of the machine.
	Pocket Air	A disturbance in the air causing the machine to drop.
	Propeller	The airscrew driven by the engine which forces the machine through the air, generally known as the "Prop."
	Protractor	An instrument for measuring angles.
	Pusher	A machine in which the propeller is fitted behind the main planes.
		Q
	Quirk	A person learning to fly ; slang term for pupil.
		R
	Race To	Refers to the practice of speeding up the revolutions of an engine to their maxi-mum.
	Radial	Refers to a type of engine in which the cylinders are set radially round the crankshaft, and are stationary.
	Radius of Action	The distance that a machine can fly from its starting point and return without replenishing the tanks. Greatly influenced by the wind factor.
	Remou	A disturbance in the air.
	Remorque	A motor trailer for carrying aeroplanes.
	Revs	Short for revolution.
	Revving	Short for revolving.
	R.F.	Representative fraction. A term indicating the scale of a map.
	Rib Compression	A rib designed to act as a strut between the front and rear spars of a wing.
	Ribs	The members used in a wing to give, strength and shape in a fore and aft direction. Often called " former ribs."
	Right and Left	Always refer to the right and left of the machine and engine as seen by the pilot sitting in his seat.
	Right and Left of a Machine	Always refers to the machine as seen from the pilot's seat.
	Roll	A manoeuvre in which the machine does a sideways turn or circle, and then continues in the same direction as before.
	Rotary	Refers to a type of engine in which the cylinders are set radially round the crankshaft and revolve.
	R.P.M.	Revolutions per minute ; generally applied to the engine.
	Rudder	A vertical controlling surface, or surfaces, set parallel with the fore and aft line of the machine, and used to control the direction of flight.
	Rudder Balanced	A vertical controlling surface set parallel with the fore and aft line of the machine, but pivoted some way back from its leading edge.
	Rudder Bar	A pivoted lever, foot-operated, control-ling the rudder.
	Rudder Post	The upright member to which the rudder is hinged.
		S
	Scout	A small single-seater machine.
	Sensitive	The reverse to soggy
	Sideslip	A sideways movement of a machine through the air either outwards or in-wards.
	Shock Absorbers	Devices for taking the shock of the machine in landing. Saaidow elastic, springs or oil are all used for this purpose.
	Skid	An inclined portion of the undercarriage or attachment to the tail which helps to take the shock of landing and drags along the ground in doing so, thus slowing up the machine.
	Slipstream of Propeller	The "wash " set up in the wake of a revolving propeller.
	Soggy	Slow on the control and heavy to handle.
	Span	The measurement of a machine transversely from wing tip to wing tip.
	Spar Main Front and Rear	The main members on which the wing is built. The front spar is generally considered the main spar, and some-times also forms the leading edge of the wing.
	Spider	The front bearing supports and plate of a rotary engine.
	Spin or Spinning Nose Dive	To go round and round in a small circle with the nose of the machine pointing directly downwards. A corkscrew descent.
	Spiral	A steeply -banked, continuous-gliding turn (with engine off).
	Splice	To unite the ends of two pieces'of wire, rope or wood. In splicing cable wire or rope the strands are interlaced.
	Squadron	An organization consisting of several flights of machines.
	Stability	The property of a machine whereby it tends to return to its normal flying position if left uncontrolled.
	Stagger	The amount that the leading edge of one wing is set in advance or behind the leading edge of the other plane, measured with the machine in the flying-level position.
	Stall	To lose flying speed.
	Strainer	See " Turnbuckle." The word can also refer to gauge or chamois leather used to strain petrol through before refilling the tanks.
	Streamline	A shape of a body that offers the least resistance to its path through the air.
	Struts	Vertical members uniting spars in upper and lower planes.
	Stunts	Unusual or exaggerated evolutions in the air.
	" S " Turns	A series of steeply-banked right and left-hand gliding turns (with engine off).
	Switch	A device for allowing or interrupting the passage of electric current generally to the sparking plugs.
		T
	Tachometer	Engine revolution counter.
	Tail	A group of planes set behind the main planes and consisting of both vertical and horizontal surfaces, used to control the balance of the machine.
	Tail Boom	The long spar connecting the main plane with the tail on a pusher machine.
	Tail Heavy	Forward pressure required on the control lever to make the machine fly level.
	Tail Plane	A fixed plane fitted parallel with the main plane, to which the elevator is attached.
	Tail Plane Lifting	A fixed plane fitted parallel witl} the main plane to which the elevator is attached. It also carries some of the weight of the machine.
	Tail Skid	See " Skid."
	Taxying	The progress of a machine on the ground with the engine running, though not fast enough to give flying speed.
	Tee	A ground sign indicating the direction of the wind. Originally an arrow, but it was found to be an improvement to widen the tip of the arrow until it be-came a T. The wind blows from the cross piece down the body of the T.
	Tender	A light motor lorry.
	Throttle Lever	Controls the amount of explosive mixture entering the engine.
	Ticket To Take	To pass an elementary flying test, and thus be registered as a certified aviator.
	Torque Engine	The reaction of a propeller which tends to cause the machine to turn about its longitudinal axis in a direction opposite to that in which the propeller is revolving.
	Tractor	A machine in which the propeller is fitted in front of the main planes.
	Trailing Edge	The rear edge of the wing.
	Trestle	Wooden frames or scaffolds designed to support the tail or wings of a machine when repairs are being carried out.
	Triplane	An aeroplane with three pairs of wings, set one above the other.
	Trueing Up	Adjusting the rigging of a machine so as to correct its balance in the air.
	Turnbuckle	A fitting used to adjust the tension of wires to which it is attached. Also called a strainer.
		U
	Undercarriage or Underchassis	That part of a machine which carries the weight of the aeroplane on the ground, and also takes the shock of landing.
		V
	Veer To	A change of wind in a clockwise direction, i.e., from N. to E.
	Vertical Bank	A loosely-applied phrase referring to any bank over 45 degrees.
	Very's Light	A coloured light fired as a signal from a special form of pistol.
	Volplane	A glide.
		W
	Warp	The yarn running lengthwise in aeroplane fabric.
	Warp To	To move the control lever sideways so as to increase or decrease the incidence on a wing with a view to raising or lowering it.
	Wash In	An increasing angle of incidence of a wing towards its wing tip.
	Wash Out	A decreasing angle of incidence of a wing towards its Wing tip.
	Weft	The yarn running crosswise in aeroplane fabric.
	Windscreen	A transparent screen mounted in front of the pilot and passenger to shield them from the rush of air by the machine in motion.
	Wind Speed	The speed of the wind.
	Wind Up	To be frightened of going into the air.
	Wing	The main supporting surface of an aeroplane.
	Wing Tip	The right or left-hand extremity, of a wing.
	Wing Tip Skids	Semi-circular,pieces of bamboo placed under the wing tips to take the shock off the wings, should the machine heel over on the ground.
	Wire Compensating or Balancing	The wire connecting opposite ailerons of top or bottom planes.
	Wires Control	See " Control Wires."
	Wires Drift	Used to transmit the head resistance set up by the wings to the main body of the machine.
	Wires Flying Drift	Internal bracing wires of a wing connected from the front spar to the rear spar diagonally outwards in each cellule.
	Wires Flying or Lift	Used to transmit the weight of the machine to the wings. They lie upwards and outwards.
	Wires Landing	Used to take the weight of the wings when the machine is on the ground. They lie downwards and outwards.
	Wires Landing Drift	Internal bracing wires of a wing connected from the front spar to the rear spar diagonally towards each cellule.
	Wire Snake	Fine wire twisted round other wires to prevent the latter fouling the propeller, should they break.
	Wires Warp	Wires used to warp the ends of the wings to control the machine laterally.
		X Y Z
	Zoom	To ascend very steeply after flying level at full speed.

	Principal source of terms: Practical Flying. Complete Course Of Flying Instruction By "A Flight Commander" - (W.G. McMinnies. R.N.)