Chapter: 02. Terms and Abbreviations

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Chapter: 02. Terms and Abbreviations

02.01 Naming Conventions

Piano follows common aerospace naming conventions, insofar as these exist in an International context. Spelling style is mostly British, for example 'aerofoil' or 'centreline' instead of 'airfoil' and 'centerline'. Some occasional mixed spelling (either 'optimise' or 'optimize') may have sneaked in (or snuck in) during different periods of development.

The 'stabiliser' ('stab' in the names of parameters) is the horizontal tail in U.S. parlance. The 'fin' is the vertical tail. Other abbreviations listed below include 'fuse' for fuselage, 'nac' for nacelle and 'u/c' for the undercarriage or 'landing gear'.

The wing 'root' position corresponds to the wing/fuselage junction or side-of-body in U.S. terminology (and not to the centreline).

The term 'eta' (Greek eta) implies a fraction of the exposed semispan (i.e. zero at the wing root, 1 at the tip), and xi (Greek xi) refers to fractions of local trapezoidal chord.

Mass rather than weight is generally preferred in the names of parameters, for example mto-mass is the maximum takeoff mass, which is numerically the same as max. takeoff weight (MTOW) in kg. or lb.

You can use either the International 'metric' system of units or the historical but still widespread 'imperial' (US/old English) system, or, astonishingly, mix the two more or less harmoniously. Details are given in Chapter#13section02 .

02.02 Abbreviations Used in Parameters

The following abbreviations are found in the names of parameters.

	a/c             aircraft
	apu             auxiliary power unit
	cd              drag coefficient (Cd) *
	cd0             zero-lift drag coefficient *
	cds             drag area (Cd * S)
	cg              centre of gravity
	cl              lift coefficient (CL) *
	clmax           maximum lift coefficient (CLmax) *
	cm0             zero-lift pitching moment coefficient *
	deg             degrees
	eta             fraction of exposed semispan  (Greek eta)
	fin             tail fin (vertical tail)
	fuse            fuselage
	l/d             lift/drag ratio
	nac             nacelle
	nac<fin>        fin-mounted nacelle
	pax             passenger(s)
	sfc             specific fuel consumption
	stab            stabiliser (horizontal tail)
	t/c             thickness/chord ratio
	t.e.            trailing edge
	vol             volume
	u/c             undercarriage (landing gear)
	xi              chordwise fraction  (Greek xi)
	xsection        cross-section
* Aero coefficients are based on wing-area unless otherwise stated.

02.03 List of Commonly Used Terms

The following common terms are used in Piano and all related documentation.

	ATC              Air Traffic Control (related to speed limit below 10,000 ft)
	AUW              All Up Weight
	BFL              Balanced Field Length
	Block            Total from engine start to shutdown (time, fuel, etc)
	BOL              Bottom of (sfc versus thrust) 'loop'.
	CAS              Calibrated Airspeed
	Cd               Drag Coefficient
	CFD              Computational Fluid Dynamics
	Cl               Lift Coefficient
	CLmax            Maximum Lift Coefficient
	Cm               Pitching moment Coefficient
	delta            Atmospheric pressure ratio (static)
	Delta            Difference, increment
	DOC              Direct Operating Cost
	EAS              Equivalent Airspeed
	EICO             Emissions Index, Carbon Monoxide
	EIHC             Emissions Index, HydroCarbons
	EINOx            Emissions Index, Oxides of Nitrogen
	FAR              Federal Aviation Regulation
	FCA              Final Cruise Altitude
	FL               Flight Level (pressure altitude in feet / 100)
	FN*              Reference engine thrust (net force)
	ICA              Initial Cruise Altitude
	ISA              International Standard Atmosphere
	JAR              Joint Airworthiness Requirements
	KCAS             Knots Calibrated Airspeed
	KEAS             Knots Equivalent Airspeed
	KTAS             Knots True Airspeed
	L/D              Lift / Drag ratio
	LFL              Landing Field Length
	LTO              Landing and Takeoff Cycle
	mac              Mean Aerodynamic Chord
	MCL              Max. Climb Rating
	MCO              Max. Continuous Rating
	MCR              Max. Cruise Rating
	Mdiv             Divergence Mach
	MEW              Manufacturer's Empty Weight
	MTO              Max. Takeoff  (rating, or mass)
	MTOW             Maximum Takeoff Weight
	MZFW             Maximum Zero Fuel Weight
	OEW              Operator's Empty Weight
	Polar            A plot of L/D (or Cd) as a function of Cl and Mach
	RoC              Rate of Climb
	RoD              Rate of Descent
	SAR              Specific Air Range (distance / fuel burn)
	SFC              Specific Fuel Consumption (lb/hr/lbf  = kg/hr/kgf)
	sigma            Atmospheric density ratio
	SL               Sea Level
	SLST             Sea Level Static Thrust
	T/W              Thrust / Weight ratio 
	TAS              True Airspeed
	theta            Atmospheric temperature ratio (static)
	TOFL             Takeoff Field Length
	U/C              Undercarriage
	WAT              Weight / Altitude / Temperature Limits
	W/S              Wing Loading (weight / wing area)
	ZFW              Zero Fuel Weight

02.04 Keyboard Terms

Unfortunately not all keyboards are the same! Please familiarise yourself with your own keyboard, and in particular the locations of the so-called 'modifier' keys. These can change the actions of some menus or provide 'keyboard equivalents' to some actions.

The relevant modifier keys are:

The Command key (also known as the apple key)

The Option key (also known as the alt key)

The Shift key

The Control key (also known as ctrl)

Other keys in this text will in general be indicated as <Key>. These include the <Tab> key and the <Space> bar. You should be able to distinguish between the <Return> and <Enter> keys. If you have doubts, use your computer's Mac Help and type in 'keyboard shortcut symbols'.

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