Contents


Piano Parameters (in alphabetic order)

Click on a parameter to see its Help:

aerofoil-clmax
aerofoil-cm0
air-condition-mass
air-traffic-speed-limit
airframe-$/mass
airframe-fixed-price-$
airframe-maintenance-coeffs
amortization-years
approach-method
approach-speed-ratio
approach-time
apu-mass
aspect-ratio
avionics-mass
blades-per-propeller
braking-friction
break-fraction-definition
buffet-cl-adjustment
buffet-mach-adjustment
buffet-mach-cl-curve
bypass-ratio
cabin-aisle-width
cabin-altitude
cabin-crew-$/hr
cabin-floor-location
cabin-in-front-fuse-fraction
cabin-in-rear-fuse-fraction
cabin-is-pressurised
cabin-seat-pitch
cabin-seat-width
cargo-doors-area
cargo-mass
cd0-compress.start-mach
cd0-compressibility-factor
centresection-is-wet
climb-schedule-switch-alt.
compressibility-method
contingency-definition
contingency-fuel-fraction
cost-method
cruise-cg-position
delta-cd-due-to-u/c
delta-clmax-due-to-slat
design-cruise-altitude
design-cruise-mach
design-dive-mach
design-floor-loading
design-n-lim
dihedral-deg
diversion-altitude-limit
diversion-distance
diversion-mach
diversion-method
dorsal-fin-height-fraction
dorsal-fin-length-fraction
drag-creep-slope
drag-creep-start
dry-engine-mass-curve
electric-systems-mass-fraction
engine-$/thrust
engine-failure-reaction-time
engine-fixed-price-$
engine-maintenance-coeffs
engine-pressure-ratio
engine-type
eta-flap
eta-u/c
eta-wet-wing
exist-2nd-deck
exist-slats
exist-winglets
fairing-type
fin-aspect-ratio
fin-cl-limit-at-vmc
fin-is-wet
fin-sweep-deg
fin-t/c
fin-tailcone-gap
fin-taper
fixed-equipment-cg-fraction
fixed-polar-name
flap-chord-fraction
flap-type
flight-crew-$/hr
front-fuse-length
front-fuse-name
fuel-density
fuel-price-$/vol
fuel-systems-mass
fuel-vol-adjustment
furnishings-mass-per-pax
fuse-depth/width
fuse-mass-method
fuse-transition
fuse-width
fuse-xsection-type
ground-handling-rate
hold-altitude
hold-mach
hold-time-mins
hydraulic-systems-mass-fraction
ignore-fuel-vol-violations
ignore-seating-checks
incidence-correction
induced-drag-method
insurance-rate
interest-rate
labor-$/hr
landing-flap-deg
landing-free-roll-time
landing-rate
landing-screen-height
linked-engine-name
lowspeed-aero-name
main-u/c-wheels-per-a/c
manufacturers-contingency-mass
mass-per-crew
mass-per-pax
mass-per-powerplant
max-landing-mass-ratio
max-operating-altitude
max-payload/design-payload
mid-fuse-length
min-static-margin
misc-systems-mass-fraction
missed-approach-time
mto-mass
mto-origin-mass
nac-depth/width
nac-length/width
nac-location-ahead-of-wing
nac-location-below-wing
nac-location-on-fuse
nac-mounted-on-fin
nac-name
nac-specific-mass
nac-width
nac<fin>-depth-proportion
nac<fin>-length-proportion
nac<fin>-longitudinal-location
nac<fin>-name
nac<fin>-vertical-location
nac<fin>-width-proportion
nacs-mounted-internally
nacs-mounted-on-fuse
nacs-mounted-on-wing
navigation-rate
nose-u/c-wheels-per-a/c
number-of-cabin-crew
number-of-compressor-stages
number-of-flight-crew
number-of-pax
number-of-shafts
number-of-windows
operational-items-mass
pax-doors-area
planform-break-fraction
planform-break-is-wet
planform-break-t.e.-adjustment
polar-mod-name
powerplant-thrust/weight
propeller-diameter
pylon-mass-ratio
ramp-fuel-allowance
rear-fuse-length
rear-fuse-name
reference-thrust-per-engine
required-fin-vol-coeff
required-stab-vol-coeff
residual-value-fraction
reverse-thrust-fraction
reverse-thrust-used-for-abort
reverse-thrust-used-for-landing
rolling-friction
roof-top-end
rr-adjust-compress.coeff1
rr-adjust-compress.coeff2
rr-adjust-compress.drag-curve
rr-adjust-compress.mdiv-curve
seats-abreast
skin-friction-method
slat-chord-fraction
slat-exp-span-fraction
span
spoiler-chord-fraction
spoiler-exp-span-fraction
stab-aspect-ratio
stab-is-wet
stab-mounting
stab-sweep-deg
stab-t/c
stab-tailcone-gap
stab-taper
stepup-cruise-method
surface-controls-mass
sweep-deg
t/c-break/root
t/c-root
t/c-tip/root
tail-mass-method
takeoff-flap-deg
takeoff-rotation-check
takeoff-screen-height
takeoff-time
taper
taxi-in-time
taxi-out-time
thickness-break-fraction
thrust-factor-at-2nd-segment
touchdown-speed-ratio
twist-deg
u/c-length-below-fuse
u/c-mounted-on
user-adjust-cl-cd-curve
user-adjust-mach-cd-curve
user-cds-increment
user-factor-on-approach-fuel
user-factor-on-asymmetric-drag
user-factor-on-box-mass
user-factor-on-climb-rating
user-factor-on-continuous-rating
user-factor-on-cruise-rating
user-factor-on-divergence-mach
user-factor-on-diversion-fuel
user-factor-on-fin-drag
user-factor-on-fin-mass
user-factor-on-flap-mass
user-factor-on-fuse-drag
user-factor-on-fuse-mass
user-factor-on-hold-fuel
user-factor-on-induced-drag
user-factor-on-landing-clmax
user-factor-on-landing-l/d
user-factor-on-nac-drag
user-factor-on-sfc
user-factor-on-stab-drag
user-factor-on-stab-mass
user-factor-on-takeoff-clmax
user-factor-on-takeoff-fuel
user-factor-on-takeoff-l/d
user-factor-on-takeoff-rating
user-factor-on-taxi-in-fuel
user-factor-on-taxi-out-fuel
user-factor-on-total-drag
user-factor-on-u/c-mass
user-factor-on-windmill-drag
user-factor-on-wing-drag
utilization-coeffs
v2-speed-ratio
v3-v2-speed-increment
window-depth
window-width
windscreen-depth
windscreen-frontal-cd
windscreen-top-fraction
windscreen-width-fraction
wing-apex-fuse-fraction
wing-area
wing-mass-method
wing-mounting
wing-transition
winglet-cant-deg
winglet-root-chord/wing-tip-chord
winglet-span/wing-halfspan
xi-front-spar-root
xi-front-spar-tip
xi-rear-spar-root
xi-rear-spar-tip
xi-sweep



Parameter Help (in alphabetic order):


AEROFOIL-CLMAX (Defaulted)

Maximum lift coefficient of the clean aerofoil
section of the wing, without high-lift devices.
Default is typical of high-subsonic long-range
designs. Low-speed designs typically achieve
higher values.
Minimum value is 1.0
Maximum value is 2.5
Default value is 1.5

AEROFOIL-CM0 (Defaulted)

Zero-lift pitching moment coefficient of the
aerofoil section of the clean wing.
Minimum value is -0.3
Maximum value is 0
Default value is -0.1

AIR-CONDITION-MASS (Calculable)

Mass of the air conditioning system.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms

AIR-TRAFFIC-SPEED-LIMIT (Defaulted)

Maximum speed limit imposed by
Air Traffic Control during climbs
and descents below 10000 feet.
Units are metres/sec or knots.
Minimum value is 100 metres/sec
Maximum value is 257.222195 metres/sec
Default value is 128.611095 metres/sec

AIRFRAME-$/MASS (Defaulted)

Airframe specific price in US$ per unit of
airframe mass, used in D.O.C. estimation.
Total airframe price is given by the sum:
airframe-fixed-price-$ +
airframe-$/mass * (airframe mass).
Units are $/kg or $/lb.
Minimum value is 0 $/kg
Maximum value is 7000 $/kg
Default value is 700.0 $/kg

AIRFRAME-FIXED-PRICE-$ (Defaulted)

Fixed component of airframe price in US$,
used in D.O.C. estimation.
Total airframe price is given by the sum:
airframe-fixed-price-$ +
airframe-$/mass * (airframe mass).
Units are US.$ or US.$.
Minimum value is 0 US.$
Maximum value is 5.0E+8 US.$
Default value is 0 US.$

AIRFRAME-MAINTENANCE-COEFFS (Defaulted)

A list of coefficients for overriding
all airframe maintenance cost calculations.
Coefficients are ordered numbers separated
by spaces. Given: c0 c1 c2 c3 c4 ...,
then Airframe Maintenance Cost {$ per flight}
= c0 (c1 + c2 T) (c3 + c4 OEW) (c5 + c6 NP)
where T = block time in hours, OEW =
operating empty mass in kg, NP = number of
pax. To simplify, latter coefficients can be
omitted or set to 1 or 0 as needed.
This parameter must be of type list
Each element must be a number > -1.0E+9
Each element must be a number < 1.0E+9
Default value is nil

AMORTIZATION-YEARS (Calculable)

Loan amortization period (years).
Default depends on cost-method.
Minimum value is 1
Maximum value is 50

APPROACH-METHOD (Defaulted)

Landing approach method, used during the
airborne phase from screen height to touchdown.
Standard method: Aircraft decelerates from the
approach-speed-ratio to touchdown-speed-ratio,
distance is found by energy considerations.
3-degree method: Constant angle from screen
to touchdown (touchdown speed found by energy),
landing may be shorter & harder than standard.
6-degree method: Similar, STOL operation only.
Legal values are:
:standard
:3-degrees
:4-degrees
:5-degrees
:6-degrees
Default value is :standard

APPROACH-SPEED-RATIO (Defaulted)

Ratio of approach speed (Vapp) to landing
stall speed. JAR25 specifies that this value
must be not less than 1.3.
Minimum value is 1.2
Maximum value is 1.6
Default value is 1.3

APPROACH-TIME (Defaulted)

Time spent at approach power, used to
calculate manoeuvre fuel allowance.
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 10 minutes
Default value is 0 minutes

APU-MASS (Calculable)

Mass of the auxiliary power unit.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms

ASPECT-RATIO (Calculable)

The trapezoidal aspect ratio of the wing.
Defined as span^2 / wing-area, where
'wing-area' is also trapezoidal. The
parameter 'span' may be supplied instead.
Minimum value is 4
Maximum value is 14

AVIONICS-MASS (Calculable)

Mass of the avionics. This is best input directly.
Internal calculation uses statistical correlation
with mto-mass.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms

BLADES-PER-PROPELLER (Defaulted)

Only relevant when engine-type is :turboprop.
Number of blades per propeller. Note that this
parameter does not impact engine performance,
and is only used to estimate windmilling drag.
Minimum value is 2
Maximum value is 20
This parameter must be of type integer
Default value is 4

BRAKING-FRICTION (Defaulted)

Effective friction coefficient during the landing
run and aborted takeoff segments, brakes on.
Minimum value is 0.1
Maximum value is 0.8
Default value is 0.4

BREAK-FRACTION-DEFINITION (Defaulted)

This decides whether the parameters:
planform-break-fraction and
thickness-break-fraction
are defined as fractions of the exposed wing
semispan (zero at the root, 1 at the tip),
or of the overall semispan (zero at the
centreline, 1 at the tip).
Legal values are:
:exposed-semispan
:overall-semispan
Default value is :exposed-semispan

BUFFET-CL-ADJUSTMENT (Defaulted)

Flat increment or decrement in predicted
initial buffet Lift Coefficients (at all
Machs). Estimated buffet CLs are shown in
drag reports, based on the trapezoidal
wing-area and without any G-factor.
See also buffet-mach-adjustment.
Minimum value is -0.5
Maximum value is 0.5
Default value is 0

BUFFET-MACH-ADJUSTMENT (Defaulted)

Flat increment or decrement in predicted
Mach numbers for initial buffeting (at
all CLs). See also buffet-cl-adjustment.
Note high-speed buffet only is considered.
Minimum value is -0.1
Maximum value is 0.1
Default value is 0

BUFFET-MACH-CL-CURVE (Defaulted)

Use this curve to override Piano's own
high-speed buffet calculations.
It is a list of numbers representing
alternately a Mach number (> 0.6) and
the corresponding buffet CL (trapez.)
This parameter must be of type list
Each element must be a number > 0.1
Each element must be a number < 1.2
Default value is nil

BYPASS-RATIO (Defaulted)

Only relevant when engine-type is :turbofan.
It is the turbofan bypass ratio. Note that
this parameter does not impact the engine
performance. It is only used to estimate the
windmilling drag and engine maintenance cost.
Minimum value is 0
Maximum value is 20
Default value is 5

CABIN-AISLE-WIDTH (Defaulted)

Cabin aisle width (single-class seating is assumed).
Units are metres or inches.
Minimum value is 0 metres
Maximum value is 2 metres
Default value is 0.45 metres

CABIN-ALTITUDE (Defaulted)

Pressure altitude that is maintained by the cabin
at the max-operating-altitude. This parameter is
only relevant when cabin-is-pressurised is true.
Units are metres or feet.
Minimum value is 0.0 metres
Maximum value is 3048.0 metres
Default value is 2438.4 metres

CABIN-CREW-$/HR (Calculable)

Cabin crew rate, U.S.$ per hour per crew member.
Default depends on cost-method.
Units are $/hour or $/hour.
Minimum value is 0 $/hour
Maximum value is 800 $/hour

CABIN-FLOOR-LOCATION (Defaulted)

Distance from the bottom of the fuselage to
the cabin floor, expressed as a fraction of
the fuselage depth. If exist-2nd-deck is true,
this value applies to the lower deck. The
upper deck will then be placed halfway between
the lower deck and the top of the fuselage.
Minimum value is 0.1
Maximum value is 0.5
Default value is 0.25

CABIN-IN-FRONT-FUSE-FRACTION (Defaulted)

Usually the cabin length is equal to mid-fuse-length.
This parameter is the fraction of front-fuse-length
that also forms part of the cabin.
Minimum value is 0
Maximum value is 0.95
Default value is 0

CABIN-IN-REAR-FUSE-FRACTION (Defaulted)

Usually the cabin length is equal to mid-fuse-length.
This parameter is the fraction of rear-fuse-length
that also forms part of the cabin.
Minimum value is 0
Maximum value is 0.95
Default value is 0

CABIN-IS-PRESSURISED (Defaulted)

Indicates whether the cabin is pressurised or not.
The degree of pressurisation is determined by
cabin-altitude and max-operating-altitude.
Legal values are:
t
nil
Default value is t

CABIN-SEAT-PITCH (Defaulted)

Seat pitch (single-class seating is assumed).
Typical deluxe value is 1.07 m. (42 inches)
Typical economy value is 0.71 m. (28 inches)
Units are metres or inches.
Minimum value is 0.6 metres
Maximum value is 2.2 metres
Default value is 0.86 metres

CABIN-SEAT-WIDTH (Defaulted)

Seat width (single-class seating is assumed).
Typical deluxe value is 0.48 m. (19 inches)
Typical economy value is 0.41 m. (16 inches)
Units are metres or inches.
Minimum value is 0.35 metres
Maximum value is 1 metres
Default value is 0.45 metres

CARGO-DOORS-AREA (Defaulted)

Total area of cargo doors (if any).
It is only relevant if the parameter
fuse-mass-method has been set to :affdl.
See also pax-doors-area.
Units are sq.metres or sq.feet.
Minimum value is 0 sq.metres
Maximum value is 20 sq.metres
Default value is 0 sq.metres

CARGO-MASS (Defaulted)

Mass of cargo in the design case.
The design payload is given by
(number-of-pax * mass-per-pax)
+ cargo-mass.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 500000.0 kilograms
Default value is 0 kilograms

CD0-COMPRESS.START-MACH (Defaulted)

The mach at which zero-lift compressibility
starts (see cd0-compressibility-factor).
Normally = mach 0.6, can be higher for
area-ruled/supercritical nacs/fuselages.
Minimum value is 0.5
Maximum value is 0.9
Default value is 0.6

CD0-COMPRESSIBILITY-FACTOR (Defaulted)

Empirical factor on high-speed profile drag
to account for any zero-lift compressibility
drag increments (e.g. due to fuselage or
nacelles). Defined as the ratio of profile
drag (Cd0) at the given design-cruise-mach to
the profile drag at Mach 0.6 (or at the given
cd0-compress.start-mach, which see).
Use 1 for low-speed a/c (M<0.6) or for very
'clean' high-speed a/c. More typical values
lie between 1.05 & 1.15 depending on the
chosen design-cruise-mach.
Minimum value is 1
Maximum value is 1.5
Default value is 1

CENTRESECTION-IS-WET (Defaulted)

Shows if the wing box centresection
(carry-through) contains fuel or not.
Legal values are:
t
nil
Default value is t

CLIMB-SCHEDULE-SWITCH-ALT. (Defaulted)

This is an altitude limit above which
the climb speed schedule always switches
to a constant Mach number. (However, the
switch normally happens at a lower altitude
when the divergence Mach is approached).
Forcing an early switch sometimes improves
climb performance for some slow aircraft
(e.g. set this to 25 or 30,000 ft.)
Units are metres or feet.
Minimum value is 5000 metres
Maximum value is 19500 metres
Default value is 10972.8 metres

COMPRESSIBILITY-METHOD (Defaulted)

Method for estimating divergence mach and
compressibility drag. The default (rae-modified)
uses roof-top-end as an aerofoil technology
parameter. The rr-adjustable method uses both
roof-top-end and additional adjustments via
rr-adjust-compress.coeff1 and
rr-adjust-compress.coeff2.
Remaining methods are older but retained for
compatibility. Compressibility drag is also
affected by user-factor-on-divergence-mach,
cd0-compressibility-factor, and drag-creep.
Note: rr-naca, rr-supercrit1, and rr-supercrit2
apply respectively to conventional (NACA),
1st-generation (1970s-80s), and 2nd-generation
(1990s) supercritical aerofoils.
Legal values are:
:rae-simple
:rae-modified
:rr-naca
:rr-supercrit1
:rr-supercrit2
:rr-adjustable
Default value is :rae-modified

CONTINGENCY-DEFINITION (Defaulted)

This sets the defining rule for the
calculation of any contingency fuel.
Also see contingency-fuel-fraction,
which sets the corresponding proportion
of mass or time, depending on the rule.
Legal values are:
:mission-fuel
:total-fuel
:mto-mass
:flight-time
Default value is :mission-fuel

CONTINGENCY-FUEL-FRACTION (Defaulted)

Contingency fraction of some mass or time,
depending on contingency-definition.
- If contingency-definition is :mission-fuel,
the contingency fuel will be a fraction
of the basic mission fuel burn.
(Use 0.05 for Typical-Intl. rules).
- If contingency-definition is :total-fuel,
the contingency fuel will be a fraction
of the total fuel load.
- If contingency-definition is :mto-mass,
the contingency fuel will be a fixed
fraction of the mto-mass.
- If contingency-definition is :flight-time,
the contingency fuel will be sufficient
to extend the normal flight time by this
fraction. (Use 0.1 for U.S.Intl.FAR121).
Minimum value is 0
Maximum value is 0.5
Default value is 0.05

COST-METHOD (Defaulted)

D.O.C. method.
AEA methods: From Association
of European Airlines, 1989.
For Piano97 use Design Range:
Short range - below 3000 nm,
Medium - 3000 to 5500 nm,
Long - 5500 to 6500 nm,
Ultra-long - above 6500 nm
Legal values are:
:aea-89-medium-range
:aea-89-long-range
:piano97-short
:piano97-medium
:piano97-long
:piano97-ultra-long
Default value is :aea-89-medium-range

CRUISE-CG-POSITION (Defaulted)

Average Centre of Gravity during
cruise, as a fraction of CG travel.
(0 = forward CG, 1 = aft CG).
CG travel is approximated by simple
on/off combinations of fuel/payload.
Minimum value is 0
Maximum value is 1
Default value is 0.5

DELTA-CD-DUE-TO-U/C (Defaulted)

Undercarriage drag coeff. {referenced to wing-area}
Minimum value is 0
Maximum value is 0.06
Default value is 0.02

DELTA-CLMAX-DUE-TO-SLAT (Defaulted)

Increment in aerofoil CLmax due to slats
or similar leading edge devices.
Only relevant when exist-slats is true.
Typically between 0.5 and 0.7, though
values > 1 are possible.
Minimum value is 0
Maximum value is 2.0
Default value is 0.5

DESIGN-CRUISE-ALTITUDE (Vital)

This altitude is used to initiate stressing
and aerodynamic calibrations. It should be
set to an approximate value representing
the expected average cruise conditions
(normally below max. operating altitude).
If in doubt, use 35000 ft. for jets (40000
for bizjets) and 25000 ft. for turboprops.
Altering its value later will affect both
the weight and aerodynamic estimates.
Units are metres or feet.
Minimum value is 5000 metres
Maximum value is 15000 metres

DESIGN-CRUISE-MACH (Vital)

This Mach is used to initiate stressing
and aerodynamic calibrations. It should be
set to an approximate value representing
typical expected fast cruise conditions,
or roughly the max.operating Mach (Mmo).
Altering its value later will affect both
the weight and aerodynamic estimates.
See also design-cruise-altitude.
Minimum value is 0.35
Maximum value is 0.95

DESIGN-DIVE-MACH (Calculable)

If not supplied, this is estimated
from the value of design-cruise-mach.
It affects certain mass estimates.
If supplied, it will also be used as
a limit for performance calculations.
Minimum value is 0.35
Maximum value is 1.0

DESIGN-FLOOR-LOADING (Defaulted)

Cabin floor design loading.
It is only relevant if the parameter
fuse-mass-method has been set to :affdl.
Typical values are 75 psf for passenger
aircraft,100 to 150 psf for utility a/c,
and 150 psf for cargo a/c.
Units are newtons/sq.m or lbs/sq.ft.
Minimum value is 2000 newtons/sq.m
Maximum value is 9000 newtons/sq.m
Default value is 3591 newtons/sq.m

DESIGN-N-LIM (Calculable)

Design limit load factor N.
Normally calculated to FAR25 rules
for gust and manoeuvre cases. The
Ultimate load factor is 1.5*N.
Minimum value is 2.0
Maximum value is 6.0

DIHEDRAL-DEG (Calculable)

Wing dihedral angle.
For 3-view purposes only.
Defined along upper wing surface.
Units are degrees or degrees.
Minimum value is -6 degrees
Maximum value is 10 degrees

DIVERSION-ALTITUDE-LIMIT (Defaulted)

This parameter can be used to ensure
that the diversion altitude does not
exceed a given value.
(Diversion altitude is normally
estimated internally so that approx.
50% of the diversion distance can be
flown under cruise conditions).
Units are metres or feet.
Minimum value is 0 metres
Maximum value is 19000 metres
Default value is 15240 metres

DIVERSION-DISTANCE (Defaulted)

Diversion distance.
This will be flown at the given value
of diversion-mach and at an altitude
which is calculated internally.
Units are metres or naut.miles.
Minimum value is 0 metres
Maximum value is 740800 metres
Default value is 370400 metres

DIVERSION-MACH (Calculable)

Unless explicitly supplied, a value of
90% of cruise mach is used internally.
Minimum value is 0.2
Maximum value is 0.9

DIVERSION-METHOD (Defaulted)

Method of calculating the required diversion
fuel. 'Revision01' uses a more accurate but
slower implementation, while the 'original'
method is more approximate, faster, and is
retained for compatibility.
Legal values are:
:original
:revision01
Default value is :revision01

DORSAL-FIN-HEIGHT-FRACTION (Defaulted)

Height of the triangular dorsal fin
(if any), expressed as a fraction of
the main fin's span.
See also dorsal-fin-length-fraction.
Dorsal is not part of the fin area or
fin volume coefficient.
Minimum value is 0
Maximum value is 0.5
Default value is 0

DORSAL-FIN-LENGTH-FRACTION (Defaulted)

Length of the base of the triangular
dorsal fin (if any), expressed as a
fraction of the main fin's root chord.
See also dorsal-fin-height-fraction.
Dorsal is not part of the fin area or
fin volume coefficient.
Minimum value is 0
Maximum value is 2
Default value is 0

DRAG-CREEP-SLOPE (Defaulted)

The aerofoil may exhibit 'drag creep', i.e.
a small and roughly constant positive slope
in the Cd versus Mach curve which starts well
before the divergence condition is reached.
drag-creep-slope is defined as this gradient
(Delta Cd) / (Delta Mach).
Creep is assumed to start at the point
drag-creep-start (which see, and which should
be specified in conjunction with the slope).
The slope is unlikely to exceed 0.005 ~ 0.01
given the default value of drag-creep-start.
Creep can significantly worsen the L/D and
is best not used with project aircraft {i.e.
assume good high-speed aerodynamic design}.
Minimum value is 0
Maximum value is 0.025
Default value is 0

DRAG-CREEP-START (Defaulted)

The aerofoil may exhibit 'drag creep', i.e.
a small and roughly constant positive slope
in the Cd versus Mach curve, starting well
before approaching the divergence condition.
drag-creep-start is defined as the ratio:
(MACH at start of creep) / (Divergence MACH).
See also drag-creep-slope, which must be
defined in parallel.
Minimum value is 0
Maximum value is 1
Default value is 0.75

DRY-ENGINE-MASS-CURVE (Defaulted)

Curve used to calculate dry engine mass.
It is a list of numbers representing
alternately the reference-thrust-per-engine
(fn*) in lbf. and the dry engine mass in lb.
Default case is roughly equivalent to:
0 0 10000 2041 20000 3877 40000 7364
60000 10717 80000 13986 100000 17194.
This parameter is ignored if powerplant mass
is input directly via 'mass-per-powerplant'
or 'powerplant-thrust/weight'.
This parameter must be of type list
Each element must be a number > 0
Each element must be a number < 200000
Default value is nil

ELECTRIC-SYSTEMS-MASS-FRACTION (Calculable)

Mass of the electrical systems, as a fraction
of the mto-mass. The internal calculation method
uses a statistical correlation with mto-mass.
Minimum value is 0
Maximum value is 0.03

ENGINE-$/THRUST (Defaulted)

Engine specific price in US$ per unit thrust
(reference FN*), used in D.O.C. estimation.
Total price per engine is given by the sum:
engine-fixed-price-$ +
engine-$/thrust * reference-thrust-per-engine
Units are $/newton or $/lbf.
Minimum value is 0 $/newton
Maximum value is 250 $/newton
Default value is 25 $/newton

ENGINE-FAILURE-REACTION-TIME (Defaulted)

Approximate time needed by the pilot to recognise
engine failure and react (throttle back, apply
brakes etc.) during accelerate-stop calculations.
Units are seconds or seconds.
Minimum value is 0 seconds
Maximum value is 6 seconds
Default value is 3 seconds

ENGINE-FIXED-PRICE-$ (Defaulted)

Fixed component of engine price in US$, used
in D.O.C. estimation. Total price per engine
is given by the sum:
engine-fixed-price-$ +
engine-$/thrust * reference-thrust-per-engine
Units are US.$ or US.$.
Minimum value is 0 US.$
Maximum value is 1.0E+8 US.$
Default value is 0 US.$

ENGINE-MAINTENANCE-COEFFS (Defaulted)

A list of coefficients for overriding the
engine maintenance cost calculations.
Numbers are separated by spaces. Given
c0 c1 c2 c3 c4 c5 c6 ..., then for 1 engine:
Engine Maintenance Cost in $ per flight
= c0 (c1 + c2 T) (c3 + c4 F) (c5 + c6 B)
(c7 + c8 S) (c9 + c10 N) (c11 + c12 P)
where T = block time in hours,
F = reference thrust per engine in Newtons,
B = bypass ratio, S = number of shafts,
N = number of compressor stages, P =
engine pressure ratio. Latter coefficients
can be omitted or set to 1 or 0 as needed.
This parameter must be of type list
Each element must be a number > -1.0E+9
Each element must be a number < 1.0E+9
Default value is nil

ENGINE-PRESSURE-RATIO (Defaulted)

Overall engine pressure ratio. Required only
for costing purposes, it does not affect the
engine performance.
Minimum value is 5.0
Maximum value is 50.0
Default value is 20

ENGINE-TYPE (Defaulted)

This parameter must appear inside the
'description' file of each engine.
Legal values are:
:turbofan
:turboprop
It may also appear in a 'plane' file, but
its value there can only be changed by
loading a different type of engine.
(Because all engine data are generic and
indistinguishable, engine-type is needed
to clarify some internal calculations.)
Legal values are:
:turbofan
:turboprop
Default value is :turbofan

ETA-FLAP (Defaulted)

Fraction of exposed semi-span occupied by
the flaps. Flaps are assumed to start at
the wing root (side-of-body, eta = 0).
Minimum value is 0.3
Maximum value is 1
Default value is 0.7

ETA-U/C (Calculable)

Spanwise location of the undercarriage,
as a fraction of the exposed semi-span.
Minimum value is 0
Maximum value is 0.5

ETA-WET-WING (Defaulted)

Spanwise limit of the wet wing.
(Position of the fuel tank's tip,
as a fraction of exposed semispan.)
Minimum value is 0.01
Maximum value is 0.99
Default value is 0.99

EXIST-2ND-DECK (Defaulted)

For a fuselage with 2 passenger decks, this
parameter should be true. Both decks are assumed
to be of equal length (the cabin length), one
directly above the other. This configuration is
only applicable to very large aircraft. {Note the
lower cargo deck is not regarded as a second deck}.
Legal values are:
t
nil
Default value is nil

EXIST-SLATS (Defaulted)

Indicates existence of leading-edge
slats or other equivalent devices.
Legal values are:
t
nil
Default value is t

EXIST-WINGLETS (Defaulted)

Indicates existence or otherwise of winglets.
Legal values are:
t
nil
Default value is nil

FAIRING-TYPE (Defaulted)

Approximate type of wing/fuselage fairing. A
minor empirical correction to the fuselage wetted
area and aerodynamics at the wing root junction.
Legal values are:
:none
:detached-high-wing
:semi-buried-high-wing
:buried-high-wing
:detached-low-wing
:low-wing-no-bulge
:low-wing-small-bulge
:low-wing-large-bulge
Default value is :none

FIN-ASPECT-RATIO (Calculable)

Aspect ratio of the vertical fin.
Defined as (fin span)^2 / (fin area).
Typically around 1.5
Minimum value is 0.7
Maximum value is 3

FIN-CL-LIMIT-AT-VMC (Defaulted)

The limiting 'lift' coefficient (sideforce)
of the vertical fin+rudder that can be used
to counter yaw due to engine-out asymmetry.
This sets the minimum-control speed Vmc
and may influence V2 (V2min >= 1.1 Vmc).
Minimum value is 0.4
Maximum value is 2.0
Default value is 0.95

FIN-IS-WET (Defaulted)

Indicates whether the fin can
hold fuel or not. Operational CG
restrictions are not considered.
cruise-cg-position may be moved aft
if fuel transfer control is used.
Legal values are:
t
nil
Default value is nil

FIN-SWEEP-DEG (Calculable)

Sweepback angle of the vertical fin.
This is always defined at the 25% chord position.
Units are degrees or degrees.
Minimum value is 0 degrees
Maximum value is 55 degrees

FIN-T/C (Defaulted)

Thickness/chord ratio of the vertical fin.
It is assumed to be constant along the span.
Minimum value is 0.05
Maximum value is 0.22
Default value is 0.11

FIN-TAILCONE-GAP (Calculable)

Horizontal gap between the trailing edge of the
vertical fin (at its root) and the tip of the
tailcone.
Units are metres or feet.
Minimum value is 0 metres
Maximum value is 10 metres

FIN-TAPER (Calculable)

Taper ratio of the vertical fin.
Minimum value is 0.18
Maximum value is 1

FIXED-EQUIPMENT-CG-FRACTION (Calculable)

Location of the Centre of Gravity of all
fixed equipment, as a fraction of the
fuselage length measured from the front.
It can be adjusted in order to move the
wing along the fuselage, on the assumption
that equipment such as batteries, A.P.U.,
etc. can be suitably distributed.
(If this parameter is fixed, the parameter
wing-apex-fuse-fraction must be free.)
Minimum value is 0.15
Maximum value is 0.8

FIXED-POLAR-NAME (Defaulted)

Name of a datafile containing a pre-defined
high-speed lift/drag polar. This overrides
Piano's own aerodynamic calculations.
To link such a file to a plane, load the
'fixed polar' from the 'Misc' menu and then
store the plane.
This parameter must be of type string
Default value is nil

FLAP-CHORD-FRACTION (Defaulted)

Chordwise fraction occupied by the nested flap.
{Measured outboard of any planform break}.
Minimum value is 0.1
Maximum value is 0.4
Default value is 0.25

FLAP-TYPE (Defaulted)

Type of trailing-edge flap system.
'FOWLER' implies a track mechanism giving
an ideal flap extension at all deflections.
'SEMI-FOWLER' implies a complex linkage
with a virtual hinge point, moving in a
path approximating the ideal.
'HINGED' implies a simple fixed hinge around
which the flap pivots in a circular arc.
Legal values are:
:3-slot-fowler
:2-slot-fowler
:2-slot-semi-fowler
:1-slot-fowler
:1-slot-semi-fowler
:hinged
Default value is :2-slot-fowler

FLIGHT-CREW-$/HR (Calculable)

Flight crew rate, U.S.$ per hour per flight
crew member. Use average value between Captain
& Co-pilot, see also number-of-flight-crew.
Salary varies substantially depending on type
of operation! Default depends on cost-method.
Units are $/hour or $/hour.
Minimum value is 0 $/hour
Maximum value is 2000 $/hour

FRONT-FUSE-LENGTH (Vital)

Length of the front section of the fuselage.
Units are metres or feet.
Minimum value is 1 metres
Maximum value is 50 metres

FRONT-FUSE-NAME (Defaulted)

Name of the file containing the shape description
for the front fuselage. The shape is automatically
adjusted to the current length, width and depth.
The shape editor can be used to create new shapes.
To link a plane to a shape, use 'load shape'
followed by 'store plane'.
This parameter must be of type string
Default value is "default"

FUEL-DENSITY (Defaulted)

Used for tankage calculations.
Approximate fuel densities are:
800 kg/m3 for JP4, 700 for gasoline.
Units are kg./cu.metre or pounds/US.gal..
Minimum value is 100 kg./cu.metre
Maximum value is 1000 kg./cu.metre
Default value is 800.0 kg./cu.metre

FUEL-PRICE-$/VOL (Calculable)

Fuel price, U.S.$ per unit volume.
Default depends on cost-method.
Units are $/cu.metre or $/US.gal..
Minimum value is 0.0 $/cu.metre
Maximum value is 1000.0 $/cu.metre

FUEL-SYSTEMS-MASS (Calculable)

Mass of the fuel systems incorporated in the
airframe. It excludes any items incorporated
in the powerplant.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms

FUEL-VOL-ADJUSTMENT (Defaulted)

Available fuel capacity (volume)
is found from wing box geometry.
This adjustment (+ or -) is for
discrepancies, fuselage tanks,
dry bays, etc. See also:
centresection-is-wet,
planform-break-is-wet,
stab-is-wet, fin-is-wet,
ignore-fuel-vol-violations.
Units are cu.metres or US.gal..
Minimum value is -100 cu.metres
Maximum value is 100 cu.metres
Default value is 0 cu.metres

FURNISHINGS-MASS-PER-PAX (Defaulted)

This parameter is totally dependent on the required
level of comfort and varies substantially between
aircraft. It can be as low as 14 kg/pax (31 lb/pax)
for small commuter types, or more than 85 kg/pax
(187 lb/pax) for long-range operations. It should
be adjusted together with the operational-items-mass
{any distinction between furnishings and operational
items is hazy and is left to the user}.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 300.0 kilograms
Default value is 32.2 kilograms

FUSE-DEPTH/WIDTH (Defaulted)

Ratio of external depth to external width
of the fuselage. It sets the fuselage depth
based on the current value of 'fuse-width'.
Minimum value is 0.5
Maximum value is 2.0
Default value is 1

FUSE-MASS-METHOD (Defaulted)

Method used for estimation of the fuselage
mass. Choice is between methods used by:
- Air Force Flight Dynamics Lab (AFFDL).
- E.Torenbeek (Subsonic Aircraft Synthesis).
The Torenbeek method provides better results,
though it ignores parameters relating to
shell modifications (doors and windows).
The AFFDL method is more detailed but
generally less accurate, and should not be
used for aircraft much larger than a B767.
Legal values are:
:affdl
:torenbeek
Default value is :torenbeek

FUSE-TRANSITION (Defaulted)

Fraction of fuselage length at which transition
to turbulent flow occurs.
Minimum value is 0
Maximum value is 0.25
Default value is 0

FUSE-WIDTH (Vital)

Maximum external width of the fuselage.
See also 'fuse-depth/width'.
Units are metres or feet.
Minimum value is 1 metres
Maximum value is 20 metres

FUSE-XSECTION-TYPE (Defaulted)

Type of fuselage cross-section.
(as per SAWE report 1025, May'74, Bullis).
The following shapes are available:
- 4 Ellipse or circle (the default).
- 6 Egg shape.
- 7 Square with slightly rounded corners.
- 8 Square with more rounded corners.
- 1 Perfect square.
- 10 Ellipsoid with flattened sides.
- 11 Ellipsoid with flattened bottom.
- double-bubble (upper and lower lobes
are separated by cabin-floor-location).
Legal values are:
4
6
7
8
1
10
11
:double-bubble
Default value is 4

GROUND-HANDLING-RATE (Calculable)

Ground handling charge in US $ per
metric ton of payload.
Minimum value is 0
Maximum value is 1000

HOLD-ALTITUDE (Defaulted)

Altitude for the hold over diversion airport.
Units are metres or feet.
Minimum value is 300 metres
Maximum value is 15000 metres
Default value is 1524 metres

HOLD-MACH (Calculable)

Mach number for the hold, normally set to
a value near the minimum drag condition.
Minimum value is 0.15
Maximum value is 0.95

HOLD-TIME-MINS (Defaulted)

Holding time at max L/D over diversion field.
Can safely be set to zero if desired.
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 90 minutes
Default value is 30 minutes

HYDRAULIC-SYSTEMS-MASS-FRACTION (Defaulted)

Mass of the hydraulic system, as a fraction of
mto-mass.
This can vary from 0.4% for small commuters,
to 1% or more for long-range aircraft with
complex redundant systems.
Minimum value is 0
Maximum value is 0.03
Default value is 0.0075

IGNORE-FUEL-VOL-VIOLATIONS (Defaulted)

If this is true, the fuel mass required
for any given range is allowed to exceed
the available volume (capacity), with
only a warning. If it is false, the fuel
mass is restricted by the capacity, so
the design range may be flown at less
than MTOW, and any range iterations
that violate the capacity will fail.
Legal values are:
t
nil
Default value is t

IGNORE-SEATING-CHECKS (Defaulted)

If set to true, this will inhibit the error
message which normally appears when the physical
dimensions of the cabin cannot accomodate the
seating configuration and/or the number of pax.
Legal values are:
t
nil
Default value is nil

INCIDENCE-CORRECTION (Defaulted)

Drag correction due to fuselage incidence.
If set to 1, a nominal drag correction is
applied. It is assumed the fuselage is
roughly level in the cruise. For values
other than 1, the drag correction is
factored. (0 = ignore correction).
Minimum value is 0
Maximum value is 10
Default value is 0

INDUCED-DRAG-METHOD (Defaulted)

Method used to estimate lift-induced
drag & trim drag contributions.
Revision98 is recommended, original
is retained for compatibility.
Legal values are:
:original
:revision98
Default value is :revision98

INSURANCE-RATE (Calculable)

Annual insurance premium, as a
fraction of aircraft delivery price.
Default may depend on cost-method.
Minimum value is 0.0
Maximum value is 0.1

INTEREST-RATE (Calculable)

Annual interest rate (expressed
as a fraction, not percentage).
Default depends on cost-method.
Minimum value is 0.0
Maximum value is 0.3

LABOR-$/HR (Calculable)

Maintenance labor rate, U.S.$ per hour.
Default depends on cost-method. Value is
ignored if 'airframe-maintenance-coeffs'
or 'engine-maintenance-coeffs' are used
to directly define maintenance costs.
Units are $/hour or $/hour.
Minimum value is 0 $/hour
Maximum value is 630 $/hour

LANDING-FLAP-DEG (Defaulted)

Flap deflection used during the landing.
Affects landing performance and flap mass.
Units are degrees or degrees.
Minimum value is 25 degrees
Maximum value is 50 degrees
Default value is 50 degrees

LANDING-FREE-ROLL-TIME (Defaulted)

Approximate 'free roll' time from touchdown to
the initial application of brakes and other
retardation devices during landing calculations.
Units are seconds or seconds.
Minimum value is 0 seconds
Maximum value is 4 seconds
Default value is 2 seconds

LANDING-RATE (Calculable)

Landing charge, US $ per metric ton.
Minimum value is 0.0
Maximum value is 100

LANDING-SCREEN-HEIGHT (Defaulted)

Screen height used for landing field estimation.
Units are metres or feet.
Minimum value is 5 metres
Maximum value is 25 metres
Default value is 15.24 metres

LINKED-ENGINE-NAME (Defaulted)

This parameter can hold the name of
an engine which is linked to a plane.
Every time the plane is loaded, the
linked engine will also be loaded.
Planes are automatically linked to
the current engine (if any) whenever
'store plane' is used.
Default value is nil

LOWSPEED-AERO-NAME (Defaulted)

Name of a datafile containing pre-defined
low-speed aerodynamics (L/D, CLmax, and
u/c drag). This overrides Piano's own
calculations. To link such a file to a
plane, load the 'lowspeed aero' from the
'Misc' menu and then store the plane.
This parameter must be of type string
Default value is nil

MAIN-U/C-WHEELS-PER-A/C (Defaulted)

Number of mainwheels per aircraft
Minimum value is 2
Maximum value is 40
This parameter must be of type integer
Default value is 4

MANUFACTURERS-CONTINGENCY-MASS (Defaulted)

Flat adjustment to the manufacturers' empty
mass (MEW), for contingencies & outfitting.
(Note operational-items-mass is separate.)
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms
Default value is 0 kilograms

MASS-PER-CREW (Defaulted)

The mass of a crew member.
(cabin and flight crew are assumed to be the same)
Units are kilograms or pounds.
Minimum value is 50 kilograms
Maximum value is 150 kilograms
Default value is 100 kilograms

MASS-PER-PAX (Defaulted)

Mass of a passenger with luggage.
The design payload is given by
(number-of-pax * mass-per-pax)
+ cargo-mass.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 500 kilograms
Default value is 95 kilograms

MASS-PER-POWERPLANT (Calculable)

Mass of an installed powerplant, including
its nacelle and pylon. If not supplied,
this parameter will be determined from the
current calues of 'powerplant-thrust/weight'
and 'reference-thrust-per-engine'.
Units are kilograms or pounds.
Minimum value is 10 kilograms
Maximum value is 50000.0 kilograms

MAX-LANDING-MASS-RATIO (Defaulted)

This parameter sets the max.landing mass (MLW).
Values <= 1 represent the ratio MLW / MTOW
(fraction of max. takeoff mass).
Values > 1 represent the ratio MLW / MZFW
(fraction of max. zero-fuel mass).
MLW influences the LFL and structural mass.
Minimum value is 0.6
Maximum value is 1.5
Default value is 1.07

MAX-OPERATING-ALTITUDE (Calculable)

If max-operating-altitude IS supplied:
It sets the fuselage pressure differential
limit. (See also cabin-altitude).
It also sets a performance limit (i.e.
engine thrust is zero at higher altitudes).
If max-operating-altitude is NOT supplied:
It is set equal to the parameter
design-cruise-altitude (to give a pressure
differential), but the aircraft may climb
higher if there is enough performance.
Units are metres or feet.
Minimum value is 5000 metres
Maximum value is 19000 metres

MAX-PAYLOAD/DESIGN-PAYLOAD (Defaulted)

Ratio of maximum to design payload.
{note: design payload = (number-of-pax
* mass-per-pax) + cargo-mass}.
This parameter is needed for Payload-Range
diagrams. It also determines the MZFW, which
may influence structural mass if Torenbeek's
wing-mass-method is used.
Minimum value is 1
Maximum value is 50
Default value is 1

MID-FUSE-LENGTH (Vital)

Length of the fuselage mid-section, which is
assumed to be of constant width and depth.
Normally also the cabin length, unless otherwise
specified by one of the cabin parameters.
Units are metres or feet.
Minimum value is 0 metres
Maximum value is 100 metres

MIN-STATIC-MARGIN (Defaulted)

The minimum acceptable static margin at the
aft-most c.g. condition.
Minimum value is -0.3
Maximum value is 0.3
Default value is 0.1

MISC-SYSTEMS-MASS-FRACTION (Calculable)

Mass of miscellaneous systems, as a fraction
of mto-mass. This item accounts for:
-Instruments
-Anti-ice
-Cargo handling
-Flight provisions
Internal calculation uses statistical
correlation with mto-mass.
Minimum value is 0
Maximum value is 0.05

MISSED-APPROACH-TIME (Defaulted)

Reserve fuel calculations can include this
allowance for a missed approach/overshoot.
The corresponding fuel mass is estimated
assuming max power throughout this time.
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 5 minutes
Default value is 0 minutes

MTO-MASS (Vital)

Design Maximum Takeoff Mass {MTOW}.
Units are kilograms or pounds.
Minimum value is 2000 kilograms
Maximum value is 900000.0 kilograms

MTO-ORIGIN-MASS (Calculable)

Normally taken to be equal to mto-mass. When
simulating a 'shrunk' derivative aircraft you
may set it to the (higher) MTOW of the original
design. It will increase the structural mass and
OEW (excessive strength, overdesigned systems).
Values less than mto-mass are not allowed.
Units are kilograms or pounds.
Minimum value is 2000 kilograms
Maximum value is 900000.0 kilograms

NAC-DEPTH/WIDTH (Defaulted)

Ratio of external depth to external width
of the nacelle. It sets the nacelle depth
based on the current value of 'nac-width'.
Minimum value is 0.5
Maximum value is 2.0
Default value is 1.0

NAC-LENGTH/WIDTH (Defaulted)

Ratio of length to external width of
the nacelle. It sets the nacelle length
based on the current value of 'nac-width'.
Note on cowled fan engines:
Only use the nacelle length of the external
cowl. The drag of any core cowl inside
the streamtube is accounted for by using
installed engine thrust data.
Minimum value is 0.1
Maximum value is 10.0
Default value is 2.0

NAC-LOCATION-AHEAD-OF-WING (Defaulted)


Distance from the front of the nacelle to the leading
edge of the wing, as a fraction of the nacelle length.
Minimum value is 0
Maximum value is 1.5
Default value is 1

NAC-LOCATION-BELOW-WING (Defaulted)


Distance from the bottom of the wing to the top of
the nacelle, as a fraction of the nacelle depth.
This is measured positive downwards, (i.e. if the
nacelle is underslung), and negative upwards.
Minimum value is -1.5
Maximum value is 0.5
Default value is 0

NAC-LOCATION-ON-FUSE (Defaulted)

Distance from the front of any fuselage-mounted
nacelles to the tip of the fuselage tailcone,
expressed as a fraction of the nacelle length.
Minimum value is 0.5
Maximum value is 4.0
Default value is 1.5

NAC-MOUNTED-ON-FIN (Defaulted)

Indicates the existence or otherwise of a
fin-mounted nacelle. See also:
nac<fin>-width-proportion
nac<fin>-depth-proportion
nac<fin>-length-proportion
Legal values are:
t
nil
Default value is nil

NAC-NAME (Defaulted)

Name of the file containing the shape description
for the nacelle. The shape is automatically
adjusted to the current length, width and depth.
The shape editor can be used to create new shapes.
To link a plane to a shape, use 'load shape'
followed by 'store plane'.
This parameter must be of type string
Default value is "default"

NAC-SPECIFIC-MASS (Calculable)

Nacelle mass per unit of wetted area
(of the external nacelles only).
This parameter is ignored if powerplant mass
is input directly via 'mass-per-powerplant'
or 'powerplant-thrust/weight'.
Units are kg/sq.m or lb/sq.ft.
Minimum value is 0 kg/sq.m
Maximum value is 200.0 kg/sq.m

NAC-WIDTH (Vital)

Maximum external width of the
nacelle for engines mounted
on the fuselage or wing.
Units are metres or feet.
Minimum value is 0.3 metres
Maximum value is 10 metres

NAC<fin>-DEPTH-PROPORTION (Defaulted)

Depth of the fin-mounted nacelle (if any),
expressed as a fraction of the depth of
the primary nacelles (which are mounted
on the wing or fuselage).
Minimum value is 0.5
Maximum value is 2.0
Default value is 1

NAC<fin>-LENGTH-PROPORTION (Defaulted)

Length of the fin-mounted nacelle (if any),
expressed as a fraction of the length of
the primary nacelles (which are mounted
on the wing or fuselage).
Minimum value is 0.5
Maximum value is 4.0
Default value is 1.5

NAC<fin>-LONGITUDINAL-LOCATION (Defaulted)

Fraction of the length of the fin-mounted
nacelle which projects ahead of the fin
leading edge.
{measured at the nacelle centreline}
Minimum value is 0
Maximum value is 0.8
Default value is 0.1

NAC<fin>-NAME (Defaulted)

Name of the file containing the shape description
for the fin-mounted nacelle.
The shape is automatically adjusted to the
current length, width and depth.
The shape editor can be used to create new shapes.
To link a plane to a shape, use 'load shape'
followed by 'store plane'.
This parameter must be of type string
Default value is "default"

NAC<fin>-VERTICAL-LOCATION (Defaulted)

Distance from the top of the fuselage to the
bottom of the fin-mounted nacelle, expressed
as a fraction of the nacelle depth.
Minimum value is 0
Maximum value is 0.5
Default value is 0.2

NAC<fin>-WIDTH-PROPORTION (Defaulted)

Width of the fin-mounted nacelle (if any),
expressed as a fraction of the width of
the primary nacelles (which are mounted
on the wing or fuselage).
Minimum value is 0.5
Maximum value is 2.0
Default value is 1

NACS-MOUNTED-INTERNALLY (Defaulted)

Only used to specify engines buried inside
the fuselage. It is a list of the longitudinal
locations of any such engines (distance from
the nose of the a/c to the engine's C.G., as
a fraction of the overall fuselage length).
Examples:
0.15 (typical single-engine tractor).
0.85 0.85 (twin-engine pusher, side-by-side).
0.17 0.83 (push-pull twin).
Note:
Nacelle dimensions will be ignored.
Nacelle and asymmetric drags = zero.
This parameter must be of type list
Each element must be a number > 0
Each element must be a number < 1
Default value is nil

NACS-MOUNTED-ON-FUSE (Defaulted)

A list of lateral locations for any nacelles
mounted on the rear fuselage.
{This parameter implicitly defines the
number of fuselage-mounted engines}.
Locations are expressed as gaps between
adjacent bodies, using fractions of the
nacelle width. For example:
0.15 0.0
specifies 4 nacelles (2 on each side), with
the gap between the fuselage and the inboard
nacelle being 15% of nac-width, and the gap
between the inboard and outboard nacelle
being 0% of nac-width.
See also nacs-mounted-on-wing.
This parameter must be of type list
Each element must be a number > 0.0
Each element must be a number < 1.0
Default value is nil

NACS-MOUNTED-ON-WING (Defaulted)

A list of the spanwise locations of any
wing-mounted nacelles, expressed as fractions
of the exposed semispan. {Implicitly, this
parameter also defines the number of engines
mounted on the wing}. Locations should be
separated by a space, for example:
0.3 0.5
This implies a 4-engined plane with nacelles
at 30% and 50% of the exposed semispan.
See also nacs-mounted-on-fuse.
This parameter must be of type list
Each element must be a number > 0
Each element must be a number < 1
Default value is nil

NAVIGATION-RATE (Calculable)

This is the constant k in the equation:
Navigation cost = k * S * (sqrt W )
Where
Navigation cost is in US $ per flight,
S is the block distance in kilometers,
W is the MTOW in metric tons.
Minimum value is 0
Maximum value is 1000

NOSE-U/C-WHEELS-PER-A/C (Defaulted)

Number of nosewheels per a/c
Minimum value is 1
Maximum value is 6
This parameter must be of type integer
Default value is 2

NUMBER-OF-CABIN-CREW (Calculable)

Total number of cabin attendants.
Minimum value is 0
Maximum value is 50
This parameter must be of type integer

NUMBER-OF-COMPRESSOR-STAGES (Defaulted)

Stages per engine (including fan). Required only
for costing purposes, it does not affect the
engine performance.
Minimum value is 5
Maximum value is 50
This parameter must be of type integer
Default value is 10

NUMBER-OF-FLIGHT-CREW (Defaulted)

Total number of flight crew.
Minimum value is 1
Maximum value is 4
This parameter must be of type integer
Default value is 2

NUMBER-OF-PAX (Vital)

Total number of passengers.
The design payload is given by
(number-of-pax * mass-per-pax)
+ cargo-mass.
Minimum value is 2
Maximum value is 1000
This parameter must be of type integer

NUMBER-OF-SHAFTS (Defaulted)

Number of spools per engine. Required only
for costing purposes, it does not affect
the engine performance.
Minimum value is 1
Maximum value is 3
This parameter must be of type integer
Default value is 2

NUMBER-OF-WINDOWS (Calculable)

Only relevant if fuse-mass-method is AFFDL.
Number of passenger windows, used in the
calculation of the fuselage mass. See
also window-depth and window-width.
Minimum value is 0
Maximum value is 1000
This parameter must be of type integer

OPERATIONAL-ITEMS-MASS (Defaulted)

Total mass of operational items not normally
supplied by the manufacturer {e.g. catering,
emergency equipment, fluids, galleys, etc}.
This parameter can be conveniently adjusted
{+ or -} to match any quoted values of OEW.
{Note: distinctions between furnishings and
operational items can be hazy, see also the
parameter furnishings-mass-per-pax}.
Units are kilograms or pounds.
Minimum value is -50000.0 kilograms
Maximum value is 50000.0 kilograms
Default value is 0 kilograms

PAX-DOORS-AREA (Calculable)

Only relevant if fuse-mass-method is AFFDL.
Total area of all normal and emergency doors
excluding cargo doors. Used in fuselage
mass calculation. (Typical values are 1.7
sq.m. per normal door and 0.75 sq.m. per
emergency door). See also cargo-doors-area.
Units are sq.metres or sq.feet.
Minimum value is 0 sq.metres
Maximum value is 200.0 sq.metres

PLANFORM-BREAK-FRACTION (Defaulted)

Spanwise position at which a break occurs
in the wing planform (as a fraction of exposed
semispan, unless otherwise specified by the
parameter 'break-fraction-definition').
The trailing edge inboard of the breakpoint
will be unswept, unless otherwise specified by
the parameter 'planform-break-t.e.-adjustment'.
Only one planform break is allowed.
Minimum value is 0
Maximum value is 0.5
Default value is 0

PLANFORM-BREAK-IS-WET (Defaulted)

Indicates whether the wing holds
fuel in the rear inboard region of
the planform break (if any). Note
this volume is normally reserved
for undercarriage retraction.
Legal values are:
t
nil
Default value is nil

PLANFORM-BREAK-T.E.-ADJUSTMENT (Defaulted)

Usually, the trailing edge (t.e.) of the wing
inboard of the planform break will be unswept.
This corresponds to the default value of 1.
Reducing the value will change the sweep of the
inboard trailing edge in a linear fashion until
(when the value becomes zero) it matches the
sweep of the trapezoidal wing's trailing edge.
Minimum value is 0
Maximum value is 1
Default value is 1

POLAR-MOD-NAME (Defaulted)

Name of a datafile containing a matrix of
modifications to the calculated lift/drag
polar, in the form (Delta Cd) = f (Mach, Cl).
It can represent adjustments due to aerofoil
characteristics or other aero corrections.
To link such a modification to a plane, load
the 'polar mod' from the 'Misc' menu and
then store the plane.
This parameter must be of type string
Default value is nil

POWERPLANT-THRUST/WEIGHT (Calculable)

Ratio of 'reference-thrust-per-engine' to
the total weight of an installed powerplant
including its nacelle and pylon.
Typical values are of the order of 3.5.
This will determine the powerplants' mass
unless a value for 'mass-per-powerplant' is
supplied.
Minimum value is 1.0
Maximum value is 10.0

PROPELLER-DIAMETER (Defaulted)

Only relevant when engine-type is :turboprop.
Propeller diameter. Note that this parameter
does not impact engine performance. It is
only used to estimate windmilling drag.
Units are metres or feet.
Minimum value is 1.5 metres
Maximum value is 10.0 metres
Default value is 3.6 metres

PYLON-MASS-RATIO (Calculable)

Pylon mass per unit of 'suspended' mass
(of dry engine + nacelle). Value is for a
nominal configuration, the calculated mass
may also depend on nacelle location.
This parameter is ignored if powerplant mass
is input directly via 'mass-per-powerplant'
or 'powerplant-thrust/weight'.
Minimum value is 0
Maximum value is 0.3

RAMP-FUEL-ALLOWANCE (Defaulted)

Difference between maximum ramp mass and
the mto-mass. If supplied, this parameter
dictates the taxi-out fuel, otherwise the
'taxi-out-time' and idle flow are used.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 5000 kilograms
Default value is 0 kilograms

REAR-FUSE-LENGTH (Vital)

Length of the rear section of the fuselage.
Units are metres or feet.
Minimum value is 1 metres
Maximum value is 50 metres

REAR-FUSE-NAME (Defaulted)

Name of the file containing the shape description
for the rear fuselage. The shape is automatically
adjusted to the current length, width and depth.
The shape editor can be used to create new shapes.
To link a plane to a shape, use 'load shape'
followed by 'store plane'.
This parameter must be of type string
Default value is "default"

REFERENCE-THRUST-PER-ENGINE (Vital)

Ref. thrust per engine (also called FN*).
It is used to scale all non-dimensional
characteristics of any engine. Typically
set at, or near, SL-ISA-Static conditions.
The available takeoff thrust may differ if
the normalised data for the 'max takeoff'
rating do not start at 1, or if the
user-factor-on-takeoff-rating is not 1.
Units are newtons or pounds-force.
Minimum value is 3000.0 newtons
Maximum value is 1000000.0 newtons

REQUIRED-FIN-VOL-COEFF (Calculable)

Vertical fin volume coefficient.
Defined as (Sf*Lf)/(Sw*b)
where
Sf = fin area.
Lf = fin arm (1/4 chord to 1/4 chord).
Sw = wing-area.
b = span.
Minimum value is 0.03
Maximum value is 0.15

REQUIRED-STAB-VOL-COEFF (Calculable)

Horizontal stabilizer volume coefficient.
Defined as (St*Lt)/(Sw*mac)
where
St = stabilizer area.
Lt = stabilizer arm (1/4 chord to 1/4 chord).
Sw = wing-area.
mac = mean aerodynamic chord.
Minimum value is 0.3
Maximum value is 2.0

RESIDUAL-VALUE-FRACTION (Calculable)

Residual value of aircraft at the end of the
amortization period, as a fraction of total
investment. Default may depend on cost-method.
Minimum value is 0
Maximum value is 0.5

REVERSE-THRUST-FRACTION (Defaulted)

Ratio of reverse thrust to normal takeoff thrust.
If there is no thrust reverser, set this to 0.
Reverse thrust is used during the landing and
aborted takeoff respectively depending on the
values of reverse-thrust-used-for-landing
and reverse-thrust-used-for-abort .
Minimum value is 0
Maximum value is 0.6
Default value is 0.3

REVERSE-THRUST-USED-FOR-ABORT (Defaulted)

Whether reverse thrust can be used during
aborted takeoffs. Some rules may allow this
if failed-engine asymmetry can be controlled.
Legal values are:
t
nil
Default value is nil

REVERSE-THRUST-USED-FOR-LANDING (Defaulted)

FAR rules do not allow any credit for using
reverse thrust during the landing run.
Legal values are:
t
nil
Default value is nil

ROLLING-FRICTION (Defaulted)

Rolling friction coefficient during takeoff run.
Minimum value is 0.005
Maximum value is 0.1
Default value is 0.02

ROOF-TOP-END (Defaulted)

The location of the end of the flat 'roof top'
pressure distribution, as a fraction of aerofoil
chord. It is used as a technology indicator for
the estimation of the Divergence Mach number.
A good early-to-mid 1990's standard is 0.6 to 0.65.
Older (1970's) supercritical aerofoils might show
values of the order of 0.5. Classical (NACA-type)
aerofoils typically show a sharp pressure peak,
corresponding to a value of 0.25.
See also user-factor-on-divergence-mach.
Minimum value is 0.1
Maximum value is 0.9
Default value is 0.5

RR-ADJUST-COMPRESS.COEFF1 (Defaulted)

Only relevant if compressibility-method
is :rr-adjustable. Empirical adjustment to
the steepness of the compressibility drag
rise (Cd versus Mach) after divergence.
Minimum value is 0
Maximum value is 10
Default value is 1

RR-ADJUST-COMPRESS.COEFF2 (Defaulted)

Only relevant if compressibility-method
is :rr-adjustable. Empirical adjustment
representing the sensitivity of the
Divergence Mach number to changes in
the lift coefficient around typical cruise
conditions. Normally between 0.1 and 0.15.
Aerofoils that are highly optimised for
the cruise show increased sensitivity.
Minimum value is 0.05
Maximum value is 0.25
Default value is 0.12

RR-ADJUST-COMPRESS.DRAG-CURVE (Defaulted)

Only relevant if compressibility-method
is :rr-adjustable. Sets the shape of the
compressibility Drag versus Mach curve.
It is a list of numbers representing
alternately the Delta-Mach and the
corresponding Cdc, where:
Delta-Mach = (Mach - Divergence Mach),
Cdc = Compressibility Cd.
Default case is roughly equivalent to:
-0.06 0.0000 -0.04 0.0001
-0.02 0.0004 0.00 0.0020
0.02 0.0074 0.03 0.0130
0.04 0.021 0.05 0.0342
This parameter must be of type list
Each element must be a number > -0.1
Each element must be a number < 1.0
Default value is nil

RR-ADJUST-COMPRESS.MDIV-CURVE (Defaulted)

Only relevant if compressibility-method
is :rr-adjustable. Adjusts the shape of
of the Divergence-Mach versus CL curve.
It is a list of numbers representing
alternately the CL and the corresponding
correction (actual Mdiv - calculated Mdiv).
Use 'drag table' to find points on the
calculated curve.
This parameter must be of type list
Each element must be a number > -0.2
Each element must be a number < 2.0
Default value is nil

SEATS-ABREAST (Vital)

Average number of cabin seats abreast
(i.e. a single-class layout is assumed).
For 2-deck designs, value is per deck.
Minimum value is 2
Maximum value is 16
This parameter must be of type integer

SKIN-FRICTION-METHOD (Defaulted)

Various methods are available for calculating Cf:
The Piano formula accounts for transition points
(e.g. wing-transition) and for compressibility.
The Boeing method is fully turbulent but also
includes compressibility effects.
The Prandtl and Karman methods are fully
turbulent and neglect compressibility.
Blasius is fully laminar and incompressible.
Legal values are:
:piano
:boeing
:prandtl
:karman
:blasius
Default value is :piano

SLAT-CHORD-FRACTION (Defaulted)

Fraction of wing chord covered by slats,
only relevant when exist-slats is true.
(Note this affects mass but not CLmax,
see 'delta-clmax-due-to-slat'.)
Minimum value is 0
Maximum value is 0.2
Default value is 0.1

SLAT-EXP-SPAN-FRACTION (Defaulted)

Fraction of exposed span covered by slats,
only relevant when exist-slats is true.
Slats will occupy the wing leading edge
from the wing tip inboard.
Minimum value is 0.25
Maximum value is 1
Default value is 1

SPAN (Calculable)

Wing span, excluding any winglets.
The parameter 'aspect-ratio' may be
supplied instead.
Units are metres or feet.
Minimum value is 5 metres
Maximum value is 150 metres

SPOILER-CHORD-FRACTION (Defaulted)

Spoiler chord as a fraction of the wing's
mean chord.
If there are no spoilers, the associated
parameter 'spoiler-exp-span-fraction'
must be set to zero.
Minimum value is 0.05
Maximum value is 0.25
Default value is 0.1

SPOILER-EXP-SPAN-FRACTION (Defaulted)

Fraction of exposed wing span occupied by spoilers.
This must be set to zero if there are no spoilers.
Minimum value is 0
Maximum value is 0.9
Default value is 0.6

STAB-ASPECT-RATIO (Defaulted)

Aspect ratio of the horizontal stabilizer.
This is defined as (stab.span)^2 / (stab.area)
where the area is gross, i.e. extended to the
fuselage centreline.
Minimum value is 3
Maximum value is 8
Default value is 5

STAB-IS-WET (Defaulted)

Indicates whether the stabiliser can
hold fuel or not. Operational CG
restrictions are not considered.
cruise-cg-position may be moved aft
if fuel transfer control is used.
Legal values are:
t
nil
Default value is nil

STAB-MOUNTING (Defaulted)

Low: Stabilizer is attached to the fuselage.
(The trailing edge is positioned at the tip
of the tailcone, but see stab-tailcone-gap).
High: Stabilizer is a T-tail on top of the fin.
(1/4-chord positions coincide at the joint).
Mid: Similar to T-tail but placed lower down
along the fin ('cruciform' configurations).
Legal values are:
:low
:mid-low
:mid
:mid-high
:high
Default value is :low

STAB-SWEEP-DEG (Calculable)

Sweepback angle of the horizontal stabilizer.
This is always defined at the 25% chord position.
Minimum value is 0
Maximum value is 60

STAB-T/C (Defaulted)

Thickness/chord ratio of the horizontal stabilizer.
It is assumed to be constant along the span.
Minimum value is 0.05
Maximum value is 0.22
Default value is 0.11

STAB-TAILCONE-GAP (Calculable)

Horizontal gap between the trailing edge of the
horizontal stabilizer (at its root) and the tip
of the tailcone. This parameter is ignored if
stab-mounting is not :low
Units are metres or feet.
Minimum value is 0 metres
Maximum value is 10 metres

STAB-TAPER (Defaulted)

Taper ratio of the horizontal stabilizer.
This is defined as (tip chord)/(centreline chord).
Minimum value is 0.18
Maximum value is 1
Default value is 0.4

STEPUP-CRUISE-METHOD (Defaulted)

If this is set to :zero-margin, step-up cruise
calculations require only just sufficient
performance to cruise at a given Flight Level.
If it is set to :300fpm@mcl, stepping must also
allow a performance margin of 300fpm RoC at
the max-climb rating and cruise Mach. Similar
considerations apply for 100 & 500 fpm. The
parameter is ignored if stepping is not used.
Legal values are:
:zero-margin
:100fpm@mcl
:300fpm@mcl
:500fpm@mcl
Default value is :300fpm@mcl

SURFACE-CONTROLS-MASS (Calculable)

Mass of the surface controls.
Units are kilograms or pounds.
Minimum value is 0 kilograms
Maximum value is 50000.0 kilograms

SWEEP-DEG (Vital)

Sweepback angle of the wing. Defined at the
chordwise position xi-sweep (normally 25%).
Units are degrees or degrees.
Minimum value is 0 degrees
Maximum value is 45 degrees

T/C-BREAK/ROOT (Defaulted)

This sets the value of t/c at the spanwise
thickness break, expressed as a fraction of
the t/c at the wing root (see 't/c-root').
The spanwise location of the thickness break is
determined by the 'thickness-break-fraction'.
Minimum value is 0.5
Maximum value is 1
Default value is 1

T/C-ROOT (Vital)

The thickness/chord ratio at the wing root.
Note that the British definition is used for
'root', meaning side-of-body, not centreline.
If there is a planform break, the t/c is of
course based on the total root chord, not
just on the trapezoidal portion!
Minimum value is 0.05
Maximum value is 0.21

T/C-TIP/ROOT (Defaulted)

This sets the value of t/c at the wing tip,
expressed as a fraction of the t/c at the
wing root (see 't/c-root').
Minimum value is 0.5
Maximum value is 1
Default value is 1

TAIL-MASS-METHOD (Defaulted)

Method used for estimating stabiliser
and fin masses. The recommended Piano
method is calibrated to known data.
Others are sample textbook methods.
Legal values are:
:piano
:torenbeek
:nicolai
Default value is :piano

TAKEOFF-FLAP-DEG (Defaulted)

Normal flap deflection used for takeoff
and 2nd-segment performance. If the minimum
2nd-segment gradient cannot be achieved, a
smaller setting may be selected internally.
Units are degrees or degrees.
Minimum value is 0 degrees
Maximum value is 35 degrees
Default value is 15 degrees

TAKEOFF-ROTATION-CHECK (Defaulted)

If takeoff rotation could cause a tailstrike:
- Piano can ignore this potential problem,
- or issue a warning during the field reports,
- or reduce rotation angle and effective CLmax.
To reduce the chances of tailstrikes, reduce
fuselage length, increase u/c-length-below-fuse
or fixed-equipment-cg-fraction, or change the
rear fuselage shape.
Legal values are:
:ignore
:warn-only
:reduce-rotation
Default value is :warn-only

TAKEOFF-SCREEN-HEIGHT (Defaulted)

Screen height used in takeoff field estimation.
Units are metres or feet.
Minimum value is 5 metres
Maximum value is 20 metres
Default value is 10.668 metres

TAKEOFF-TIME (Defaulted)

Time spent at takeoff power, used to
calculate manoeuvre fuel allowance
from brake release to screen height.
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 3 minutes
Default value is 0 minutes

TAPER (Vital)

Taper ratio of the trapezoidal wing. Defined as the
ratio of tip-chord to the chord of the trapezoidal
wing at the fuselage centreline.
Consistent with the definition of wing-area.
Minimum value is 0.18
Maximum value is 1

TAXI-IN-TIME (Defaulted)

Used to find taxi-in fuel allowance at
destination. This is assumed to be taken from
the reserve fuel and so will only impact D.O.C.
calculations. If non-zero, the idle fuel flow
at S.L. static is used (and therefore must
be covered by the engine characteristics).
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 15 minutes
Default value is 0 minutes

TAXI-OUT-TIME (Defaulted)

Used to find the taxi-out fuel allowance at
departure. This is calculated assuming idle
fuel flow (therefore engine data should
include the S.L. static idle condition).
Note: if 'ramp-fuel-allowance' is supplied
(non-zero) it overrides this calculation.
Units are minutes or minutes.
Minimum value is 0 minutes
Maximum value is 15 minutes
Default value is 0 minutes

THICKNESS-BREAK-FRACTION (Calculable)

Spanwise position at which a break occurs in
the wing thickness distribution (as a fraction
of exposed semispan, unless otherwise specified
by the parameter 'break-fraction-definition').
If not supplied, its value is determined from
'planform-break-fraction'. The local t/c is
determined by 't/c-break/root'. Thickness will
vary linearly between the root, break, and tip
positions. Only one break is assumed.
Minimum value is 0
Maximum value is 0.5

THRUST-FACTOR-AT-2ND-SEGMENT (Defaulted)

This factor can be used to account for any emergency
thrust rating used after engine failure on takeoff.
Minimum value is 0.7
Maximum value is 1.5
Default value is 1

TOUCHDOWN-SPEED-RATIO (Defaulted)

Ratio of touchdown speed to landing stall
speed (Vtd/Vs). Reflects piloting technique
during a standard approach. Reducing Vtd for
a standard Vapp means a longer 'hold-off'
period which may increase the LFL. An
excessive Vtd would imply use of engine
thrust and may have the same effect.
Minimum value is 1.05
Maximum value is 1.25
Default value is 1.15

TWIST-DEG (Defaulted)

Wing twist at the tip (washout, i.e.
must be negative). A linear-lofted
spanwise distribution is assumed.
Units are degrees or degrees.
Minimum value is -7 degrees
Maximum value is 0 degrees
Default value is 0 degrees

U/C-LENGTH-BELOW-FUSE (Calculable)

Distance from the bottom of the fuselage to
the ground. Dictates undercarriage length.
Units are metres or feet.
Minimum value is 0.1 metres
Maximum value is 5 metres

U/C-MOUNTED-ON (Defaulted)

Dictates whether undercarriage is mounted on
the fuselage or on the wing. Together with
u/c-length-below-fuse it determines the
length of the u/c.
Legal values are:
:fuse
:wing
Default value is :wing

USER-ADJUST-CL-CD-CURVE (Defaulted)

User-adjustment of CL-dependent drag.
It is a list of numbers representing
alternately a CL and a corresponding
Cd increment or decrement.
(referenced to trapezoidal wing-area).
This parameter must be of type list
Each element must be a number > -1.0
Each element must be a number < 1.0
Default value is nil

USER-ADJUST-MACH-CD-CURVE (Defaulted)

User-adjustment of Mach-dependent drag.
It is a list of numbers representing
alternately a Mach number and a
corresponding Cd increment ().
(referenced to trapezoidal wing-area).
This parameter must be of type list
Each element must be a number > -1.0
Each element must be a number < 1.0
Default value is nil

USER-CDS-INCREMENT (Defaulted)

Drag area increment {Cd * S}
for any unaccounted items.
Units are sq.metres or sq.feet.
Minimum value is -10 sq.metres
Maximum value is 10 sq.metres
Default value is 0 sq.metres

USER-FACTOR-ON-APPROACH-FUEL (Defaulted)

Factor applied to approach fuel.
Minimum value is 0
Maximum value is 5.0
Default value is 1

USER-FACTOR-ON-ASYMMETRIC-DRAG (Defaulted)

Factor applied to asymmetric drag due
to yaw with one engine out. See also
user-factor-on-windmill-drag .
Minimum value is 0.0
Maximum value is 2.0
Default value is 1

USER-FACTOR-ON-BOX-MASS (Defaulted)

This factor is applied to the wing structural mass
only. A separate factor exists for the flaps.
Minimum value is 0.1
Maximum value is 2
Default value is 1

USER-FACTOR-ON-CLIMB-RATING (Defaulted)

Applied to engine thrust characteristics
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-CONTINUOUS-RATING (Defaulted)

Applied to engine thrust characteristics
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-CRUISE-RATING (Defaulted)

Applied to engine thrust characteristics
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-DIVERGENCE-MACH (Defaulted)

Divergence Mach is calculated internally as
a function of t/c, sweepback, CL, and the
parameter roof-top-end.
This factor is then applied to the result.
The divergence Mach at a given CL can be
examined through the drag report.
Minimum value is 0.9
Maximum value is 1.1
Default value is 1

USER-FACTOR-ON-DIVERSION-FUEL (Defaulted)

Factor applied to diversion fuel calculation.
Minimum value is 0.1
Maximum value is 2.0
Default value is 1

USER-FACTOR-ON-FIN-DRAG (Defaulted)

Factor applied to the fin zero-lift drag
Minimum value is 0
Maximum value is 5
Default value is 1

USER-FACTOR-ON-FIN-MASS (Defaulted)

Factor on estimated vertical tail mass.
Minimum value is 0
Maximum value is 10
Default value is 1

USER-FACTOR-ON-FLAP-MASS (Defaulted)

There are no comments on this parameter
Minimum value is 0.1
Maximum value is 5
Default value is 1

USER-FACTOR-ON-FUSE-DRAG (Defaulted)

Factor applied to fuselage zero-lift drag
Minimum value is 0
Maximum value is 5
Default value is 1

USER-FACTOR-ON-FUSE-MASS (Defaulted)

Factor on estimated fuselage mass.
Minimum value is 0.1
Maximum value is 2
Default value is 1

USER-FACTOR-ON-HOLD-FUEL (Defaulted)

Factor applied to holding fuel calculation.
Minimum value is 0.1
Maximum value is 2.0
Default value is 1

USER-FACTOR-ON-INDUCED-DRAG (Defaulted)

Factor applied to the wing induced drag.
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-LANDING-CLMAX (Defaulted)

This factor is applied to the total CLmax of
the aircraft at landing flap deflections.
See also:
aerofoil-clmax,
delta-clmax-due-to-slat.
Minimum value is 0.5
Maximum value is 2
Default value is 1

USER-FACTOR-ON-LANDING-L/D (Defaulted)

This factor is applied to the calculated
overall Lift/Drag ratio in the landing
configuration (shown in field reports).
Use it to change the final approach and
landing drags.
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-NAC-DRAG (Defaulted)

Factor applied to nacelle zero-lift drag
Minimum value is 0
Maximum value is 5
Default value is 1

USER-FACTOR-ON-SFC (Defaulted)

This factor is applied to all fuel consumption
characteristics (sfc loops and idle flow).
Minimum value is 0.1
Maximum value is 2
Default value is 1

USER-FACTOR-ON-STAB-DRAG (Defaulted)

Factor applied to stabilizer zero-lift drag
Minimum value is 0
Maximum value is 5
Default value is 1

USER-FACTOR-ON-STAB-MASS (Defaulted)

Factor on estimated horizontal tail mass.
Minimum value is 0
Maximum value is 10
Default value is 1

USER-FACTOR-ON-TAKEOFF-CLMAX (Defaulted)

This factor is applied to the total CLmax of
the aircraft at takeoff flap deflections.
See also:
aerofoil-clmax,
delta-clmax-due-to-slat.
Minimum value is 0.5
Maximum value is 2
Default value is 1

USER-FACTOR-ON-TAKEOFF-FUEL (Defaulted)

Factor applied to takeoff fuel.
Minimum value is 0
Maximum value is 5.0
Default value is 1

USER-FACTOR-ON-TAKEOFF-L/D (Defaulted)

This factor is applied to the calculated
overall Lift/Drag ratio in the takeoff
configuration (shown in field reports).
Use it to change the takeoff drag.
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-TAKEOFF-RATING (Defaulted)

This factor should only be used to simulate
an engine de-rating or throttle-push when
calculating takeoff performance. The given
value of reference-thrust-per-engine
will still be used to find the engine mass,
and all other ratings will still be defined
relative to the reference thrust.
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-TAXI-IN-FUEL (Defaulted)

Factor applied to taxi-in fuel.
Minimum value is 0
Maximum value is 5.0
Default value is 1

USER-FACTOR-ON-TAXI-OUT-FUEL (Defaulted)

Factor applied to taxi-out fuel.
Minimum value is 0
Maximum value is 5.0
Default value is 1

USER-FACTOR-ON-TOTAL-DRAG (Defaulted)

A factor applied to the total drag. This
should only be used for management-style
studies and has limited physical significance.
Minimum value is 0.5
Maximum value is 1.5
Default value is 1

USER-FACTOR-ON-U/C-MASS (Defaulted)

Factor on undercarriage mass.
Minimum value is 0
Maximum value is 2
Default value is 1

USER-FACTOR-ON-WINDMILL-DRAG (Defaulted)

Factor applied to windmilling drag due
to a failed engine. See also
user-factor-on-asymmetric-drag .
Minimum value is 0.0
Maximum value is 2.0
Default value is 1

USER-FACTOR-ON-WING-DRAG (Defaulted)

Factor applied to wing zero-lift drag
Minimum value is 0
Maximum value is 5
Default value is 1

UTILIZATION-COEFFS (Defaulted)

A list of coefficients for overriding
utilization calculations in DOC methods.
Coefficients are 2 numbers separated
by spaces. Given: k1 k2 , then:
Utilization in trips per year
= k1 / (T + k2)
Where T = block time in hours.
If k2 is not given, it is assumed zero.
This parameter must be of type list
Each element must be a number > 0
Each element must be a number < 8760
Default value is nil

V2-SPEED-RATIO (Defaulted)

Ratio of takeoff safety speed (V2) to takeoff
stall speed. JAR25 specifies that this value
must be not less than 1.2. Overspeeding may
be used to improve the 2nd.segment gradient.
Minimum value is 1.1
Maximum value is 1.5
Default value is 1.2

V3-V2-SPEED-INCREMENT (Defaulted)

Typical difference between the
all-engines-operative screen speed
(V3) and takeoff safety speed (V2).
V3-V2 varies with piloting technique.
Units are metres/sec or knots.
Minimum value is 0 metres/sec
Maximum value is 15 metres/sec
Default value is 5.144444 metres/sec

WINDOW-DEPTH (Defaulted)

Only relevant if fuse-mass-method is AFFDL.
Used in the fuselage mass estimation.
Units are metres or inches.
Minimum value is 0 metres
Maximum value is 0.9 metres
Default value is 0.356 metres

WINDOW-WIDTH (Defaulted)

Only relevant if fuse-mass-method is AFFDL.
Used in the fuselage mass estimation.
Units are metres or inches.
Minimum value is 0 metres
Maximum value is 0.9 metres
Default value is 0.254 metres

WINDSCREEN-DEPTH (Defaulted)

Windscreen depth. See also windscreen-top-fraction
which determines the windscreen vertical location.
Units are metres or feet.
Minimum value is 0.0 metres
Maximum value is 1.0 metres
Default value is 0.5 metres

WINDSCREEN-FRONTAL-CD (Defaulted)

Windscreen Cd referenced to the windscreen's
frontal area. The value of 0.035 is typical
of modern conformal contoured windscreens.
Minimum value is 0.0
Maximum value is 0.08
Default value is 0.035

WINDSCREEN-TOP-FRACTION (Calculable)

Distance from the top of fuselage to the top of
the windscreen, as a fraction of fuselage depth.
If not specified, the windscreen will be placed
at the point where the front fuselage shape
first becomes concave (if possible).
Minimum value is 0.01
Maximum value is 0.6

WINDSCREEN-WIDTH-FRACTION (Defaulted)

Windscreen width as a fraction of local fuse
width. (Definition of local width: In a front
view of the fuselage, draw a horizontal line
halfway down the windscreen, take the length
of this line within the fuselage).
Minimum value is 0.0
Maximum value is 1
Default value is 0.8

WING-APEX-FUSE-FRACTION (Calculable)

A fraction giving the longitudinal wing
location. It is the distance from the nose
of the aircraft to the 'apex' of the wing,
divided by the fuselage length.
(The 'apex' is the intersection of the wing's
extended leading edge with the centreline).
(If this parameter is fixed, the parameter
fixed-equipment-cg-fraction must be free.)
Minimum value is 0.1
Maximum value is 0.9

WING-AREA (Vital)

The trapezoidal wing area. Defined
by extending the outboard leading and
trailing edges to the centreline,
ignoring any inboard planform break.
It is consistent with the definition of
'aspect-ratio' and 'taper', and is the
default reference area in aerodynamic
reports. Alternative wing areas (airbus,
wimpress etc.) are calculated internally
based on this area.
Units are sq.metres or sq.feet.
Minimum value is 10.0 sq.metres
Maximum value is 1500.0 sq.metres

WING-MASS-METHOD (Defaulted)

Wing weight estimation method.
- The original (default) method is
industry-derived and calibrated.
- The Torenbeek method is courtesy Prof.
E.Torenbeek (TU Delft report LR-693) and
is best suited to very large aircraft:
- tor-693 implements LR-693 unmodified.
- tor-mod implements a provisional
correction to a known inconsistency in
LR-693 and uses the original equations
for secondary weights (flaps,slats,etc).
- tor-mod-allev further assumes that
active controls alleviate gust/manoeuvre
loads (non-critical case is chosen).
Legal values are:
:original
:tor-693
:tor-mod
:tor-mod-allev
Default value is :original

WING-MOUNTING (Defaulted)

Position of the wing on the fuselage.
Legal values are:
:high
:mid
:low
Default value is :low

WING-TRANSITION (Defaulted)

Fraction of wing chord at which boundary layer
transition to turbulent flow occurs.
Used in skin friction calculations.
Minimum value is 0
Maximum value is 0.75
Default value is 0

WINGLET-CANT-DEG (Defaulted)

Winglet cant from the vertical.
Has secondary effect only.
Minimum value is 0
Maximum value is 90
Default value is 15

WINGLET-ROOT-CHORD/WING-TIP-CHORD (Defaulted)

Fraction of wing tip chord
occupied by winglet.
Has secondary effect only.
Minimum value is 0.2
Maximum value is 1
Default value is 0.5

WINGLET-SPAN/WING-HALFSPAN (Defaulted)

Span of a single winglet, as a fraction of the
wing halfspan. This affects the induced drag
and wing weight estimates.
Minimum value is 0.04
Maximum value is 0.25
Default value is 0.15

XI-FRONT-SPAR-ROOT (Defaulted)

Front spar location at the wing root,
fraction of trapezoidal chord
Minimum value is 0.05
Maximum value is 0.35
Default value is 0.15

XI-FRONT-SPAR-TIP (Defaulted)

Front spar location at the box tip,
fraction of chord
Minimum value is 0.05
Maximum value is 0.35
Default value is 0.15

XI-REAR-SPAR-ROOT (Defaulted)

Rear spar location at the wing root,
fraction of trapezoidal chord
Minimum value is 0.5
Maximum value is 0.9
Default value is 0.65

XI-REAR-SPAR-TIP (Defaulted)

Rear spar location at the box tip,
fraction of chord
Minimum value is 0.5
Maximum value is 0.9
Default value is 0.65

XI-SWEEP (Defaulted)

Chordwise fraction at which the wing sweepback
angle is defined. (Normally 0.25)
Minimum value is 0
Maximum value is 1
Default value is 0.25

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