Glossary of Terms

AA – Anti-Aircraft, that is ground to air artillery.


Air Group - The basic flying unit within the Imperial Navy, comprised of three squadrons, with an airborne strength of 27 aircraft; therefore equivalent to an RAF/RAAF wing, to a USAAF group, or to an Imperial Army Air Regiment.


Air Regiment – The basic flying unit within the Imperial Army, comprised of three companies, with an airborne strength of 18-27 aircraft; therefore equivalent to an RAF/RAAF wing or to an Imperial Navy Air Group.


AOC – ‘Air Officer Commanding’, an RAF/RAAF term for an officer of general rank commanding an air force higher organisation, such as a Group, Area, or Command HQ; the air force equivalent of a GOC or ‘General Officer Commanding’.


Arse-end Charlie – The last aircraft to enter combat or a laggard within the formation; so often the first victim of fighter attack.


B-24 – An American four-engined heavy bomber, noted for its long range and heavy armament; known as the ‘Liberator’.


Balbo – A large formation of aircraft. This term was used, albeit inconsistently, within the RAF/RAAF for wing formations consisting of a squadron or more. It refers to the eminent fascist aviator, Italo Balbo, who led a 12-aircraft formation across the Atlantic in 1930 and a 24-aircraft formation around the world in 1933.


Beaufighter – A large heavily-armed twin-engined two-seat fighter made by the Bristol company in the UK, based upon the Beaufort bomber.


Boost – The pressure density of the fuel/air mixture in the carburettor induction chamber, measured in British aircraft in pounds per square inch, achieved through mechanical compression in the supercharger, and controlled by the throttle lever; this artificially-produced air density permitted high engine power to be maintained in spite of reducing atmospheric air pressure with altitude.


Bunt – A negative G flight manoeuvre in which the stick is moved forward, causing the nose to tuck under and the aircraft to describe the first half of an inverted loop.


Cannon – In this book, an automatic weapon of 20mm calibre; unlike machine guns, these weapons featured explosive shells.


Circuit – The airspace immediately around and above the airfield, divided up spatially into a curved invisible pathway along which pilots circled the field on approach to land.


CO – ‘Commanding Officer’, of a unit - in the RAF/RAAF, of a squadron or wing.


CSU – The propeller ‘Constant Speed Unit’, which maintained propeller revolutions at a selected value, by automatically adjusting the angle of the propeller blades irrespective of throttle setting or flight attitude; controlled by the propeller pitch lever, positioned alongside the throttle (or boost) lever in the throttle quadrant.


daisy-cutter – An anti-personnel bomb, fused to explode above the ground and scatter shrapnel widely; therefore it does not crater the ground.


deflection shooting – Leading a moving target by aiming ahead of it, in the manner of skeet shooting; maximum deflection was 90°, namely firing from a point perpendicular to the target’s flight path.


Dispersal, dispersals – Areas for parking and servicing squadron aircraft, located away from the main airfield, connected to it by taxiways.


Donryu – The Nakajima Ki.49 army heavy bomber, referred to by Allied fighter pilots by the reporting name, ‘Helen’.


D-ring – The handle attached to the parachute ripcord.


Feet, Foot – In this book, a measurement of altitude, 3.28 feet to one metre.


Fighter Command – The RAF formation responsible for UK-based fighter operations; the parent organisation of the three Spitfire squadrons before their transfer to Australia.


Flight, e.g. ‘A’ Flight – An organisational sub-unit within a squadron, usually two to a squadron, led by a flight commander, one of the CO’s deputies.


Forced-landing – A landing made through necessity not choice, usually due to mechanical defect, combat damage, adverse weather, or navigational error; usually made away from the airfield, usually with damage to the aircraft.


Gallon – A unit of volume, 4.5 litres to an Imperial gallon, 3.7 litres to a US gallon.


GCI – ‘Ground-controlled interception’, referring to the specialised radar sets which provided this capability, namely the radar tracking and plotting of single aircraft rather than whole formations.


G4M – The Imperial Navy’s ‘Land Attack Plane Type 1’; made by Mitsubishi, it was the enemy bomber type most often encountered over Darwin; referred to by Allied fighter pilots by the reporting name,  ‘Betty’.


Glycol – Ethylene glycol, used in a 70/30 percent water/glycol mix, used as a liquid coolant and therefore a medium for removing heat from the engine combustion chambers; it also raised the boiling point of the water; therefore permitting higher power outputs to be achieved without overheating the engine.


Group – In the USAAF and most other air forces, the basic organisational unit, typically comprised of three squadrons; therefore equivalent to an RAF/RAAF wing (confusingly, an RAF/RAAF ‘group’ denoted the next level up, and was thus the equivalent of a USAAF wing!).


Half roll – A flight manoeuvre by which the aircraft is rolled through 180°, usually from level flight to inverted, permitting the pilot to change direction rapidly by pulling into a downwards vertical manoeuvre such as a half loop; therefore the first half of a ‘Split S’.


Hayabusa – ‘Peregrine Falcon’, the Imperial Army’s main fighter type, the Nakajima Ki.43; referred to by Allied fighter pilots by the reporting name, ‘Oscar’.


Hudson – A twin-engined light bomber produced by the US firm Lockheed and widely used by the RAF/RAAF, based upon the prewar L-14 airliner.


IAS – Indicated Air Speed, namely the airspeed shown on the aircraft’s airspeed indicator; but this under-reads in proportion to height, such that 200 knots IAS at 30 000 feet represented a true airspeed (TAS) of more than 300 knots.


Immelmann turn – An aerobatic manoeuvre in the vertical plane which resembles a loop in the first half; however, instead of continuing to pull through, the pilot rolls out at the top, thus completing a 180 degree change of direction with a height gain.


Imperial Army/Navy – the Japanese army/navy.


Incendiary – Ammunition designed to set alight to combustibles such as petrol, by means of a flaming flare at the base of the bullet.


Ki.43 – The Imperial Army’s main fighter type, known as the Hayabusa; often confused with the Zero by Allied fighter pilots, and referred to by them by the reporting name, ‘Oscar’.


Ki.48 – A twin-engined light bomber type of the Imperial Army, referred to by Allied fighter pilots by the reporting name, ‘Lily’. Comparable to the Bristol Blenheim and Martin Maryland.


Ki.49 – A twin-engined heavy bomber type of the Imperial Army, referred to by Allied fighter pilots by the reporting name, ‘Helen’. Comparable to the North American B-25 Mitchell.


Kittyhawk – The RAF name for the Curtiss P-40 fighter, an American type widely used by the RAF and RAAF.


Knot – In this book, a unit of airspeed: a nautical mile per hour; 1.85 kph.


Line abreast – Many usages of this term depending on context, but in this book it primarily denotes a tactical formation in which the aircraft fly roughly alongside one another; within the RAF, this term was often used to denote what was otherwise known as a ‘finger four’.


Line astern – A tactical formation in which the aircraft fly behind one another at intervals; but by 1943 used only for the approach phase of a combat (theoretically at least).


Loop – An aerobatic manoeuvre in the vertical plane, whereby the aircraft pulls up vertically until it is inverted, then recovers into the same attitude as it started, its flight path thereby describing a circle in the sky.


NT – ‘Northern Territory’, one of the two territories directly governed by the Australian Federal Government in Canberra.


NWA – ‘North-western Area’ RAAF HQ, the higher command organisation responsible for directing the NT-based air war.


OBU – ‘Operational Base Unit’, an administrative and logistical unit responsible for running an airfield.


Ops room – The Operations Room within the Fighter Sector organisation, connected by phone and radio with all parts of the air defence apparatus, where the relative positions of both enemy and friendly forces were plotted on a plotting board, and from which controllers issued orders to pilots.


OTU – ‘Operational Training Unit’ in the RAF/RAAF; these schools converted pilots to front-line aircraft types and drilled them in the tactical rudiments of combat flying.


Overshoot – Moving beyond a given reference point, either in a gunnery pass or in landing, because of excessive speed and inertia.


Port – Left, on or to the left-hand side.


RAF – ‘Royal Air Force’, that is, the British air force.


RAAF – ‘Royal Australian Air Force’.


Revs – Revolutions per minute, see rpm.


Roll – an aerobatic manoeuvre whereby the aircraft rotates about the axis of its fuselage.


Rpm – Revolutions per minute, a measurement of engine speed counted on the tachometer by revolutions of the crankshaft.


R/T – Radio transceiver, that is, voice radio – VHF in Spitfires.


Scramble – RAF terminology, meaning ‘get airborne as quickly as possible to engage the enemy’.


Section – In RAF/RAAF, an airborne element within a squadron, ranging from two to six aircraft; referred to in USAAF as an ‘element’ if two aircraft, or a ‘flight’ if four.


Sortie – An operational flight by one aircraft. Thus a squadron mission which involved 12 aircraft would produce 12 sorties, but only one ‘operation’.


Spin – A situation in which an aeroplane has ‘departed from controlled flight’, during which it descends vertically at an enormous rate of descent, auto-rotating about the vertical axis, with the nose pointing steeply at the ground; in combat, it occurs through losing too much airspeed in a turn, or using the controls too coarsely; in perfectly behaved aircraft like Spitfires and Zeros, the pilot can recover at will from a spin by applying opposite rudder and easing the backward pressure on the stick, but nonetheless much height is lost before recovery.


Squadron – In RAF/RAAF, the basic flying unit; a NWA fighter squadron consisted of about 20 aircraft, about 30 pilots, and about 300 ground staff.


Stall – A situation in which an aeroplane’s wing loses the airspeed necessary to maintain flight, upon which the nose pitches downward, often attended by wing drop in the direction of the turn (this is the starting point for a spin); in well behaved aircraft like the Spitfire and the Zero, the pilot can recover at will by easing backward pressure on the stick – if he has enough height.


Starboard – Right, on or to the right hand side.


SWPA – The ‘South West Pacific Area’, General Douglas MacArthur’s command, embracing the area from Australia northward through New Guinea, and westward to the islands of Indonesia and the Philippines.


Tally-ho – A radio call indicating, ‘I have the enemy in sight and will now continue the interception visually (and thanks for the radar vectors)’.


TAS – True air speed, that is, the speed at which the aircraft moves through the airmass; except at very low altitude, this is always greater than the speed shown on the pilot’s airspeed indicator. Thus a TAS of 320 knots at 30 000 feet will indicate as only about 200 knots on the airspeed indicator, because of air pressure reducing with altitude.


Undershoot – Failing to reach the desired three dimensional point in space; as applied to landing, this is when the aircraft is travelling along a glide slope such that it would hit the ground before reaching the runway.


Up sun – In the direction of the sun, moving towards the sun, looking in the direction of the sun.


USAAF – The United States Army Air Forces, that is, the air force of the US Army, as distinct from those of the US Navy or US Marines.


Vector – A steering instruction from the ground-based controller, namely a specified magnetic heading to achieve the desired relative positioning in the air – typically to intercept the enemy.


Vee – an aircraft formation in the shape of an inverted V, with the leader at the apex; referred to in original RAF/RAAF sources as a ‘Vic’, reflecting an archaic phonetic alphabet.


Wing – In RAF/RAAF, a tactical and administrative organisation usually consisting of three squadrons, equivalent to a group or regiment in other air forces.


Wingman – An American term referring to the pilot who guarded the tail of the section or element leader; this generic term lacked an RAF/RAAF equivalent, the specified role being undertaken by the No.2 or No.4 in a section.


W/T – Wireless transceiver, that is, two-way morse radio.


Zero – The Mitsubishi Type ‘0’ Carrier Fighter of the Imperial Navy; referred to by Allied fighter pilots by the reporting name ‘Zeke’ if it was the round wing-tipped Model 21 or 22; or as ‘Hap’ if it was the square wing-tipped Model 32.