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OpenSuSE: Fix inconsistent line-feeds in READMEs Also drop a stray ".bak" file. Thanks to OpenSuSE build service.
2011-08-01 17:45:13 +00:00
Coordinate system notes: All positions specified are in meters (which
is weird, since all other units in the file are English). The X axis
points forward, Y is left, and Z is up. Take your right hand, and
hold it like a gun. Your first and second fingers are the X and Y
axes, and your upwards-pointing thumb is the Z. This is slightly
different from the coordinate system used by JSBSim. Sorry. The
origin can be placed anywhere, so long as you are consistent. I use
the nose of the aircraft.
XML Elements
------------
airplane: The top-level element for the file. It contains only one
attribute:
mass: The empty (no fuel) weight, in pounds.
approach: The approach parameters for the aircraft. The solver will
generate an aircraft that matches these settings. The element
can (and should) contain <control> elements indicating pilot
input settings, such as flaps and throttle, for the
approach.
speed: The approach airspeed, in knots TAS.
aoa: The approach angle of attack, in degrees
fuel: Fraction (0-1) of fuel in the tanks. Default is 0.2.
cruise: The cruise speed and altitude for the solver to match. As
above, this should contain <control> elements indicating
aircraft configuration. Especially, make sure the engines
are generating enough thrust at cruise!
speed: The cruise speed, in knots TAS.
alt: The cruise altitude, in feet MSL.
fuel: Fraction (0-1) of fuel in the tanks. Default is 0.2.
cockpit: The location of the cockpit (pilot eyepoint).
x,y,z: eyepoint location (see coordinates note)
fuselage: This defines a tubelike structure. It will be given an even
mass and aerodynamic force distribution by the solver. You
can have as many as you like, in any orientation you please.
ax,ay,az: One end of the tube (typically the front)
bx,by,bz: The other ("back") end.
width: The width of the tube, in meters.
taper: The approximate radius at the "tips" of the fuselage
expressed as a fraction (0-1) of the width value.
midpoint: The location of the widest part of the fuselage,
expressed as a fraction of the distance between A and B.
idrag: Multiplier for the "induced drag" generated by this
object. Default is one. With idrag=0 the fuselage
generates only drag.
cx,cy,cz: Factors for the generated drag in the fuselages "local
coordinate system" with x pointing from end to front,
z perpendicular to x with y=0 in the aircraft coordinate
system. E.g. for a fuselage of a height of 2 times the
width you can define cy=2 and (due to the doubled front
surface) cx=2.
wing: This defines the main wing of the aircraft. You can have
only one (but see below about using vstab objects for extra
lifting surfaces). The wing should have a <stall> subelement to
indicate stall behavior, control surface subelements (flap0,
flap1, spoiler, slat) to indicate what and where the control
surfaces are, and <control> subelements to map user input
properties to the control surfaces.
x,y,z: The "base" of the wing, specified as the location of
the mid-chord (not leading edge, trailing edge, or
aerodynamic center) point at the root of the LEFT
(!) wing.
length: The length from the base of the wing to the midchord
point at the tip. Note that this is not the same
thing as span.
chord: The chord of the wing at its base, along the X axis
(not normal to the leading edge, as it is
sometimes defined).
incidence: The incidence angle at the wing root, in degrees.
Zero is level with the fuselage (as in an
aerobatic plane), positive means that the leading
edge is higher than the trailing edge (as in a
trainer).
twist: The difference between the incidence angle at the
wing root and the incidence angle at the wing
tip. Typically, this is a negative number so
that the wing tips have a lower angle of attack
and stall after the wing root (washout).
taper: The taper fraction, expressed as the tip chord
divided by the root chord. A taper of one is a
hershey bar wing, and zero would be a wing ending
at a point. Defaults to one.
sweep: The sweep angle of the wing, in degrees. Zero is
no sweep, positive angles are swept back.
Defaults to zero.
dihedral: The dihedral angle of the wing. Positive angles
are upward dihedral. Defaults to zero.
idrag: Multiplier for the "induced drag" generated by this
surface. In general, low aspect wings will
generate less induced drag per-AoA than high
aspect (glider) wings. This value isn't
constrained well by the solution process, and may
require tuning to get throttle settings correct in
high AoA (approach) situations.
camber: The lift produced by the wing at zero angle of
attack, expressed as a fraction of the maximum
lift produced at the stall AoA.
hstab: These defines the horizontal stabilizer of the aircraft.
Internally, it is just a wing object and therefore works the
same in XML. You are allowed only one hstab object; the
solver needs to know which wing's incidence to play with to
get the aircraft trimmed correctly.
vstab: A "vertical" stabilizer. Like hstab, this is just another
wing, with a few special properties. The surface is not
"mirrored" as are wing and hstab objects. If you define a
left wing only, you'll only get a left wing. The default
dihedral, if unspecified, is 90 degrees instead of zero.
But all parameters are equally settable, so there's no
requirement that this object be "vertical" at all. You can
use it for anything you like, such as extra wings for
biplanes. Most importantly, these surfaces are not involved
with the solver computation, so you can have none, or as
many as you like.
mstab: A mirrored horizontal stabilizer. Exactly the same as wing, but
not involved with the solver computation, so you can have none,
or as many as you like.
stall: A subelement of a wing (or hstab/vstab/mstab) that specifies the
stall behavior.
aoa: The stall angle (maximum lift) in degrees. Note that
this is relative to the wing, not the fuselage (since
the wing may have a non-zero incidence angle).
width: The "width" of the stall, in degrees. A high value
indicates a gentle stall. Low values are viscious
for a non-twisted wing, but are acceptable for a
twisted one (since the whole wing will not stall at
the same time).
peak: The height of the lift peak, relative to the
post-stall secondary lift peak at 45 degrees.
Defaults to 1.5. This one is deep voodoo, and
probably doesn't need to change much. Bug me for an
explanation if you're curious.
flap0, flap1, slat, spoiler:
These are subelements of wing/hstab/vstab objects, and specify
the location and effectiveness of the control surfaces.
start: The position along the wing where the control
surface begins. Zero is the root, one is the tip.
end: The position where the surface ends, as above.
lift: The lift multiplier for a flap or slat at full
extension. One is a no-op, a typical aileron might
be 1.2 or so, a giant jetliner flap 2.0, and a
spoiler 0.0. For spoilers, the interpretation is a
little different -- they spoil only "prestall" lift.
Lift due purely to "flat plate" effects isn't
affected. For typical wings that stall at low AoA's
essentially all lift is pre-stall and you don't have
to care. Jet fighters tend not to have wing
spoilers, for exactly this reason. This value is
not applicable to slats, which affect stall AoA
only.
drag: The drag multiplier, as above. Typically should be
higher than the lift multiplier for flaps.
aoa: Applicable only to slats. This indicates the
angle by which the stall AoA is translated by the
slat extension.
thruster: A very simple "thrust only" engine object. Useful for
things like thrust vectoring nozzles. All it does is map
its THROTTLE input axis to its output thrust rating. Does
not consume fuel, etc...
thrust: Maximum thrust in pounds
x,y,z: The point on the airframe where thrust will be
applied.
vx,vy,vy: The direction of the thrust in airframe
coordinates. The vector will be normalized
automatically, so any non-zero vector will work
fine.
jet: A turbojet/fan engine. It accepts a <control> subelement to map a
property to its throttle setting, and an <actionpt> subelement
to place the action point of the thrust at a different
position than the mass of the engine.
x,y,z: The location of the engine, as a point mass.
If no actionpt is specified, this will also
be the point of application of thrust.
mass: The mass of the engine, in pounds.
thrust: The maximum sea-level thrust, in pounds.
afterburner: Maximum total thrust with afterburner/reheat,
in pounds [defaults to "no additional
thrust"].
rotate: Vector angle of the thrust in degrees about the
Y axis [0].
n1-idle: Idling rotor speed [55].
n1-max: Maximum rotor speed [102].
n2-idle: Idling compressor speed [73].
n2-max: Maximum compressor speed [103].
tsfc: Thrust-specific fuel consumption [0.8].
This should be considerably lower for modern
turbofans.
egt: Exhaust gas temperature at takeoff [1050].
epr: Engine pressure ratio at takeoff [3.0].
exhaust-speed: The maximum exhaust speed in knots [~1555].
spool-time: Time, in seconds, for the engine to respond to
90% of a commanded power setting.
propeller: A propeller. This element requires an engine subtag.
Currently <piston-engine> and <turbine-engine> are
supported.
x,y,z: The position of the mass (!) of the
engine/propeller combination. If the point
of force application is different (and it
will be) it should be set with an <actionpt>
subelement.
mass: The mass of the engine/propeller, in pounds.
moment: The moment, in kg-meters^2. This has to be
hand calculated and guessed at for now. A
more automated system will be forthcoming.
Use a negative moment value for
counter-rotating ("European" -- CCW as seen
from behind the prop) propellers.
A good guess for this value is the radius of
the prop (in meters) squared times the mass
(kg) divided by three; that is the moment of
a plain "stick" bolted to the prop shaft.
radius: The radius, in meters, or the propeller.
cruise-speed: The max efficiency cruise speed of the
propeller. Generally not the same as the
aircraft's cruise speed.
cruise-rpm: The RPM of the propeller at max-eff. cruise.
cruise-power: The power sunk by the prop at cruise, in horsepower.
cruise-alt: The reference cruise altitude in feet.
takeoff-power: The takeoff power required by the propeller...
takeoff-rpm: ...at the given takeoff RPM.
min-rpm: The minimum operational RPM for a constant speed
propeller. This is the speed to which the
prop governor will seek when the blue lever
is at minimum. The coarse-stop attribute
limits how far the governor can go into trying
to reach this RPM.
max-rpm: The maximum operational RPM for a constant speed
propeller. See above. The fine-stop attribute
limits how far the governor can go in trying
to reach this RPM.
fine-stop: The minimum pitch of the propeller (high RPM) as a
ratio of ideal cruise pitch. This is set to 0.25
by default -- a higher value will result in a
lower RPM at low power settings (e.g. idle, taxi,
and approach).
coarse-stop: The maximum pitch of the propeller (low RPM) as
a ratio of ideal cruise pitch. This is set to
4.0 by default -- a lower value may result in a
higher RPM at high power settings.
gear-ratio: The factor by which the engine RPM is multiplied
to produce the propeller RPM. Optional (defaults
to 1.0).
contra: When set (contra="1"), this indicates that the
propeller is a contra-rotating pair. It
will not contribute to the aircraft's net
gyroscopic moment, nor will it produce
asymmetric torque on the aircraft body.
Asymmetric slipstream effects, when
implemented, will also be zero when this is
set.
piston-engine: A piston engine definition. This must be a subelement
of an enclosing <propeller> tag.
eng-power: Maximum BHP of the engine at sea level.
eng-rpm: The engine RPM at which eng-power is developed
displacement: The engine displacement in cubic inches.
compression: The engine compression ratio.
turbo-mul: The turbo/super-charger pressure multiplier.
Static pressure will be multiplied by this
value to get the manifold pressure.
wastegate-mp: The maximum manifold pressure. Beyond
this, the gate will release to keep the
MP below this number. (inHG). This value
can be changed at runtime using the
WASTEGATE control axis, which is a
multiplier in the range [0:1].
turbo-lag: Time lag, in seconds, for 90% of a power change
to be reflected in the turbocharger boost
pressure.
turbine-engine: A turbine engine definition. This must be a subelement
of an enclosing <propeller> tag.
eng-power: Maximum BHP of the engine at a suitable
cruise altitude.
eng-rpm: The engine RPM at which eng-power is
developed. Note that this is "shaft" RPM
as seen by the propeller. Don't use a
gear-ratio on the enclosing propeller, or
else you'll get confused. :)
alt: The altitude at which eng-power is developed.
This should be high enough to be lower (!)
than the flat-rating power.
flat-rating: The maximum allowed power developed by
the engine. Most turboprops are flat
rated below a certain altitude and
temperature range to prevent engine
damage.
min-n2: N2 (percent) turbine speed at zero throttle.
max-n2: N2 (percent) turbine speed at max throttle.
bsfc: Specific fuel consumption, in lbs/hr per
horsepower.
actionpt: Defines an "action point" for an enclosing jet or propeller
element. This is the location where the force from the thruster
will be applied.
x,y,z: The location of force application.
gear: Defines a landing gear. Accepts <control> subelements to map
properties to steering and braking. Can also be used to simulate
floats. Although the coefficients are still called ..fric, it
is calculated in fluids as a drag (proportional to the square
of the speed). In fluids gears are not considered to detect
crashes (as on ground).
x,y,z: The location of the fully-extended gear tip.
compression: The distance in meters along the "up" axis that
the gear will compress.
initial-load: The initial load of the spring in multiples of
compression. Defaults to 0. (With this parameter
a lower spring-constants will be used for the
gear-> can reduce numerical problems (jitter))
Note: the spring-constant is varied from 0%
compression to 20% compression to get continuous
behavior around 0 compression. (could be physically
explained by wheel deformation)
upx/upy/upz: The direction of compression, defaults to
vertical (0,0,1) if unspecified. These are
used only for a direction -- the vector need
not be normalized, as the length is specified
by "compression".
sfric: Static (non-skidding) coefficient of
friction. Defaults to 0.8.
dfric: Dynamic friction. Defaults to 0.7.
spring: A dimensionless multiplier for the automatically
generated spring constant. Increase to make
the gear stiffer, decrease to make it
squishier.
damp: A dimensionless multiplier for the automatically
generated damping coefficient. Decrease to
make the gear "bouncier", increase to make it
"slower". Beware of increasing this too far:
very high damping forces can make the numerics
unstable. If you can't make the gear stop
bouncing with this number, try increasing the
compression length instead.
on-water: if this is set to "0" the gear will be ignored if
on water. Defaults to "0"
on-solid: if this set to "0" the gear will be ignored if
not on water. Defaults to "1"
speed-planing:
spring-factor-not-planing:
At zero speed the spring factor is multiplied by
spring-factor-not-planing. Above speed-planing this
factor is equal to 1. The idea is, to use this for
floats simulating the transition from swimming to
planing. speed-planing defaults to 0,
spring-factor-not-planing defaults to 1.
reduce-friction-by-extension: at full extension the friction is
reduced by this relative value. 0.7 means 30% friction
at full extension. If you specify a value greater
than one, the friction will be zero before reaching
full extension. Defaults to "0"
ignored-by-solver: with the on-water/on-solid tags you can have more
than one set of gears in one aircraft, If the solver
(who automatically generates the spring constants)
would take all gears into account, the result would be
wrong. E. G. set this tag to "1" for all gears, which
are not active on runways. Defaults to "0". You can
not exclude all gears in the solving process.
launchbar: Defines a catapult launchbar or strop. The default acceleration
provided by the catapult is 25m/s^2. This can be
modified by the use of the control axis LACCEL.
x,y,z: The location of the mount point of the launch bar or
strop on the aircraft.
length: The length of the launch bar from mount point to tip
down-angle: The max angle below the horizontal the
launchbar can achieve.
up-angle: The max angle above the horizontal the launchbar
can achieve.
holdback-{x,y,z}: The location of the holdback mount point
on the aircraft.
holdback-length: The length of the holdback from mount
point to tip. Note: holdback up-angle and
down-angle are the same as those defined
for the launchbar and are not specified in
the configuration.
tank: A fuel tank. Tanks in the aircraft are identified
numerically (starting from zero), in the order they are
defined in the file. If the left tank is first, "tank[0]"
will be the left tank.
x,y,z: The location of the tank.
capacity: The maximum contents of the tank, in pounds. Not
gallons -- YASim supports fuels of varying
densities.
jet: A boolean. If present, this causes the fuel
density to be treated as Jet-A. Otherwise,
gasoline density is used. A more elaborate
density setting (in pounds per gallon, for
example) would be easy to implement. Bug me.
ballast: This is a mechanism for modifying the mass distribution of
the aircraft. A ballast setting specifies that a particular
amount of the empty weight of the aircraft must be placed at
a given location. The remaining non-ballast weight will be
distributed "intelligently" across the fuselage and wing
objects. Note again: this does NOT change the empty weight
of the aircraft.
x,y,z: The location of the ballast.
mass: How much mass, in pounds, to put there. Note that
this value can be negative. I find that I often need
to "lighten" the tail of the aircraft.
weight: This is an added weight, something not part of the empty
weight of the aircraft, like passengers, cargo, or external
stores. The actual value of the mass is not specified here,
instead, a mapping to a property is used. This allows
external code, such as the panel, to control the weight
(loading a given cargo configuration from preference files,
dropping bombs at runtime, etc...)
x,y,z: The location of the weight.
mass-prop: The name of the fgfs property containing the
mass, in pounds, of this weight.
size: The aerodynamic "size", in meters, of the
object. This is important for external stores,
which will cause drag. For reasonably
aerodynamic stuff like bombs, the size should be
roughly the width of the object. For other
stuff, you're on your own. The default is zero,
which results in no aerodynamic force (internal
cargo).
solve-weight:
Subtag of approach and cruise parameters. Used to specify a
non-zero setting for a <weight> tag during solution. The
default is to assume all weights are zero at the given
performance numbers.
idx: Index of the weight in the file (starting with zero).
weight: Weight setting in pounds.
control-input:
This element manages a mapping from fgfs properties (user
input) to settable values on the aircraft's objects. Note
that the value to be set MUST (!) be valid on the given
object type. This is not checked for by the parser, and
will cause a runtime crash if you try it. Wing's don't have
throttle controls, etc... Note that multiple axes may be
set on the same value. They are summed before setting.
axis: The name of the double-valued fgfs property "axis" to
use as input, such as "/controls/flight/aileron".
control: Which control axis to set on the objects. It can have
the following values:
THROTTLE - The throttle on a jet or propeller.
MIXTURE - The mixture on a propeller.
REHEAT - The afterburner on a jet
PROP - The propeller advance
BRAKE - The brake on a gear.
STEER - The steering angle on a gear.
INCIDENCE - The incidence angle of a wing.
FLAP0 - The flap0 deflection of a wing.
FLAP1 - The flap1 deflection of a wing.
FLAP[0/1]EFFECTIVENESS - a multiplier for flap lift, but not drag
(useful for blown flaps)
SLAT - The slat extension of a wing.
SPOILER - The spoiler extension for a wing.
CYCLICAIL - The "aileron" cyclic input of a rotor
CYCLICELE - The "elevator" cyclic input of a rotor
COLLECTIVE - The collective input of a rotor
ROTORENGINEON - If not equal zero the rotor is rotating
WINCHRELSPEED - The relative winch speed
LACCEL - The acceleration provided by the catapult.
{... and many more, see FGFDM.cpp ...}
invert: Negate the value of the property before setting on
the object.
split: Applicable to wing control surfaces. Sets the
normal value on the left wing, and a negated value
on the right wing.
square: Squares the value before setting. Useful for
controls like steering that need a wide range, yet
lots of sensitivity in the center. Obviously only
applicable to values that have a range of [-1:1] or
[0:1].
src0/src1/dst0/dst1:
If present, these defined a linear mapping from the
source to the output value. Input values in the
range src0-src1 are mapped linearly to dst0-dst1,
with clamping for input values that lie outside the
range.
control-output:
This can be used to pass the value of a YASim control axis
(after all mapping and summing is applied) back to the
property tree.
control: Name of the control axis. See above.
prop: Property node to receive the value.
side: Optional, for split controls. Either "right" or "left"
min/max: Clamping applied to output value.
control-speed:
Some controls (most notably flaps and hydraulics) have
maximum slew rates and cannot respond instantly to pilot
input. This can be implemented with a control-speed tag,
which defines a "transition time" required to slew through
the full input range. Note that this tag is
semi-deprecated, complicated control input filtering can be
done much more robustly from a Nasal script.
control: Name of the control axis. See above.
transition-time: Time in seconds to slew through input range.
control-setting:
This tag is used to define a particular setting for a
control axis inside the <cruise> or <approach> tags, where
obviously property input is not available. It can be used,
for example, to inform the solver that the approach
performance values assume full flaps, etc...
axis: Name of the control input (i.e. a property name)
value: Value of the control axis.
hitch: A hitch, can be used for winch-start (in gliders) or aerotow (in
gliders and motor aircrafts) or for external cargo with helicopter.
You can do aerotow over the net via multiplayer (see j3 and bocian
as an example).
name: the name of the hitch. must be aerotow if you want to do
aerotow via multiplayer. You will find many properties
at /sim/hitches/name. Most of them are directly tied to
the internal variables, you can modify them as you like.
You can add a listener to the property "broken", e. g. for
playing a sound.
x,y,z: The position of the hitch
force-is-calculated-by-other: if you want to simulate aerotowing
over the internet, set this value to "1" in the motor
aircraft. Don't specify or set this to zero in gliders.
In a LAN the time lag might be small enough to set it on
both aircrafts to "0". It's intended, that this is done
automatically in the future.
tow: The tow used for aerotow or winch. This must be a subelement
of an enclosing <hitch> tag.
length: upstretched length in m
weight-per-meter: in kg/m
elastic-constant: lower values give higher elasticity
break-force: in N
mp-auto-connect-period: the every x seconds a towed multiplayer
aircraft is searched. If found, this tow is connected
automatically, parameters are copied from the other
aircraft. Should be set only in the motor aircraft, not
in the glider
winch: The tow used for aerotow or winch. This must be a subelement
of an enclosing <hitch> tag.
max-tow-length:
min-tow-length:
initial-tow-length: all are in m. The initial tow length also
defines the length/search radius used for the mp-autoconnect
feature
max-winch-speed: in m/s
power: in kW
max-force: in N
rotor: A rotor. Used for simulating helicopters. You can have one, two
or even more.
There is a drawing of a rotor in the Doc-directory
(README.yasim.rotor.png) Please find the measures from this drawing
for several parameters in square brackets [].
If you specify a rotor, you do not need to specify a wing or hstab,
the settings for approach and cruise will be ignored then. You have
to specify the solver results manually. See below.
The rotor generates downwash acting on all stabs, surfaces and
fuselages. For all fuselages in the rotor downwash you should
specify idrag="0" to get realistic results.
name: The name of the rotor.
(some data is stored at /rotors/name/)
The rpm, cone angle, yaw angle and roll angle are stored
for the complete rotor. For every blade the position
angle, the flap angle and the incidence angle are stored.
All angles are in degree, positive values always mean "up".
This is not completely tested, but seem to work at least
for rotors rotating counterclockwise.
A value stall gives the fraction of the rotor in stall
(weighted by the fraction the have on lift and drag
without stall). Use this for modifying the rotor-sound.
x,y,z: The position of the rotor center
nx,ny,nz: The normal of the rotor (pointing upwards, will be
normalized by the computer)
fx,fy,fz: A Vector pointing forward, if not perpendicular to the
normal it will be corrected by the computer
diameter: The diameter in meter [D]
numblades: The number of blades
weightperblade: The weight per blade in pounds
relbladecenter: The relative center of gravity of the blade. Maybe
not 100% correct interpreted; use 0.5 for the start and
change in small steps [b/R]
chord: The chord of the blade its base, along the X axis
(not normal to the leading edge, as it is
sometimes defined). [c]
twist: The difference between the incidence angle at the
blade root and the incidence angle at the wing
tip. Typically, this is a negative number so
that the rotor tips have a lower angle of attack.
taper: The taper fraction, expressed as the tip chord
divided by the root chord. A taper of one is a
bar blade, and zero would be a blade ending
at a point. Defaults to one. [d/c]
rel-len-where-incidence-is-measured: If the blade is twisted,
you need a point where to measure the incidence angle.
Zero means at the base, 1 means at the tip. Typically
it should be something near 0.7
rel-len-blade-start: Typically the blade is not mounted in the
center of the rotor [a/R]
rpm: rounds per minute.
phi0: initial position of this rotor
ccw: determines if the rotor rotates clockwise (="0") or
counterclockwise (="1"), (if you look on the top of the
normal, so the bo105 has counterclockwise rotor).
"true" and "false" are not any longer supported to
increase my lifespan. ;-)
maxcollective: The maximum of the collective incidence in degree
mincollective: The minimum of the collective incidence in degree
maxcyclicele: The maximum of the cyclic incidence in degree for
the elevator like function
mincyclicele: The minimum of the cyclic incidence in degree for
the elevator like function
maxcyclicail: The maximum of the cyclic incidence in degree for
the aileron like function
mincyclicail: The minimum of the cyclic incidence in degree for
the aileron like function
airfoil-incidence-no-lift: non symmetric airfoils produces lift
with no incidence. This is is the incidence, where the
airfoil is producing no lift. Zero for symmetrical airfoils
(default)
incidence-stall-zero-speed:
incidence-stall-half-sonic-speed: the stall incidence is a function
of the speed. I found some measured data, where this is
linear over a wide range of speed. Of course the linear
region ends at higher speeds than zero, but just
extrapolate the linear behavior to zero.
lift-factor-stall: In stall airfoils produce less lift. Without
stall the c-lift of the profile is assumed to be
sin(incidence-"airfoil-incidence-no-lift")*liftcoef;
And in stall:
sin(2*(incidence-"airfoil-incidence-no-lift"))*liftcoef*...
..."lift-factor-stall";
Therefore this factor is not the quotient between lift
with and without stall. Use 0.28 if you have no idea.
drag-factor-stall: The drag of an airfoil in stall is larger than
without stall.
Without stall c-drag is assumed to be
abs(sin(incidence-"airfoil-incidence-no-lift"))...
..*dragcoef1+dragcoef0);
With stall this is multiplied by drag-factor
stall-change-over: For incidence<"incidence-stall" there is no stall.
For incidence>("incidence-stall"+"stall-change-over") there
is stall. In the range between this incidences it is
interpolated linear.
pitch-a:
pitch-b: collective incidence angles, If you start flightgear
with --log-level=info, flightgear reports lift and needed
power for theses incidence angles
forceatpitch-a:
poweratpitch-b:
poweratpitch-0: old tokens, not supported any longer, the result are
not exactly the expected lift and power values. Will be
removed in one of the next updates.directly.Use "real"
coefficients instead (see below) and adjust the lift with
rotor-correction-factor.
The airfoil of the rotor is described as follows:
The way is to define the lift and drag coefficients directly.
Without stall the c-lift of the profile is assumed to be
sin(incidence-"airfoil-incidence-no-lift")*liftcoef;
And in stall:
sin(2*(incidence-"airfoil-incidence-no-lift"))*liftcoef*...
..."lift-factor-stall";
Without stall c-drag is assumed to be
abs(sin(incidence-"airfoil-incidence-no-lift"))...
..*dragcoef1+dragcoef0);
See above, how the coefficients are defined with stall.
The parameters:
airfoil-lift-coefficient: liftcoef
airfoil-drag-coefficient0: dragcoef0
airfoil-drag-coefficient1: dragcoef1
To find the right values: see README.yasim.rotor.ods
(Open Office file) or README.yasim.rotor.xls (Excel
file). With theses files you can generate graphs of the
airfoil coefficients and adjust the parameters to match
real airfoils. For many airfoils you find data published
in the internet. Parameters for the airfoils NACA 23012
(main rotor of bo105) and NACA 0012 (tail rotor of bo105?)
are included.
rotor-correction-factor:
If you calculate the lift of a heli rotor or even of a
propeller, you get a value larger than the real measured
one. (Due to vortex effects.) This is considered in the
simulation, but with a old theory by Prantl, which is known
to give still too large. This is corrected by this token,
default: 1
flapmin: Minimum flapping angle. (Should normally never reached)
flapmax: Maximum flapping angle. (Should normally never reached)
flap0: Flapping angle at no rotation, i.e. -5
dynamic: this changes the reactions speed of the rotor to an input.
normally 1 (Maybe there are rotors with a little faster
reaction, than use a value a little greater than one.
A value greater than one will result in a more inert,
system. Maybe it's useful for simulating the rotor of the
Bell UH1
rellenflaphinge: The relative length from the center of the rotor
to the flapping hinge. Can be taken from pictures of the
helicopter (i.e. 0 for Bell206, about 0.05 for most
rotors) For rotors without flapping hinge (where the blade
are twisted instead, i.e. Bo 105, Lynx) use a mean value,
maybe 0.2. This value has a extreme result in the behavior
of the rotor [F/r]
sharedflaphinge: determines, if the rotor has one central flapping
hinge (="1") for the blades (like the Bell206 or the tail
rotor of the Bo 105), default is "0".
delta3: Some rotors have a delta3 effect, which results in a
decreasing of the incidence when the rotor is flapping.
A value of 0 (as most helicopters have) means no change in
incidence, a value of 1 result in a decreases of one degree
per one degree flapping.
So delta3 is the proportional factor between flapping and
decrease of incidence. I.e. the tail rotor of a Bo105 has
a delta3 of 1.
In some publications delta3 is described by an angle. The
value in YASim is the atan of this angle
delta: A factor for the damping constant for the flapping. 1 means
a analytical result, which is only a approximation. Has a
very strong result in the reaction of the rotor system on
control inputs.
If you know the flapping angle for a given cyclic input you
can adjust this by changing this value. Or if you now the
maximum roll rate or ...
translift-maxfactor: Helicopters have "translational lift", which
is due to turbulence. In forward flying the rotor gets less
turbulence air and produces more lift. The factor is the
quotient between lift at high airspeeds to the lift at
hover (with same pitch).
translift-ve: the speed, where the translational lift reaches 1/e of
the maximum value. In m/s.
ground-effect-constant: Near to the ground the rotor produces more
torque than in higher altitudes. The ground effect is
calculated as
factor = 1+diameter/altitude*"ground-effect-constant"
number-of-parts:
number-of-segments: The rotor is simulated in "number-of-parts"
different directions.
In every direction the rotor is simulated at
number-of-segments points. If the value is to small, the
rotor will react unrealistic. If it is to high, cpu-power
will be wasted. I now use a value of 8 for
"number-of-parts" and 8 for number-of-segments for the main
rotor and 4 for "number-of-parts" and 5 for
"number-of-segments" for the tail rotor.
"number-of-parts" must be a multiple of 4 (if not, it
is corrected)
cyclic-factor: The response of a rotor to cyclic input is hard to
calculate (its a damped oscillator in resonance, some
parameters have very large impact to the cyclic response)
With this parameter (default 1) you can adjust the
simulator to the real helo.
downwashfactor: A factor for the downwash of the rotor, default 1.
balance: The balance of the rotor. 1.0: the rotor is 100% balanced,
0.0: half of the blades are missing. Use a value near one
(0.98 ... 0.999) to add some vibration.
tiltcenterx:
tiltcentery:
tiltcenterz: The center for the tilting of the complete rotorhead/
mast. Can be used for simulating of the Osprey or small
autogyros.
mintiltyaw:
mintiltpitch:
mintiltroll:
maxtiltyaw:
maxtiltpitch:
maxtiltroll: The limits (in degree) for tilting the rotor head
All rotor can have <control> subelements for the cyclic
(CYCLICELE, CYCLICAIL) and collective (COLLECTIVE) input.
and can have <control> subelements for the tilting the whole rotor
head around the y-axis (TILTPITCH), the x-axis (TILTROLL) and the
z-axis (TILTYAW). ROTORBALANCE is a factor for the balance.
rotorgear: If you are using one or more rotors you have to define a
rotorgear. It connects all the rotors and adds a simple engine.
In future it will be possible, to add a YASim-engine.
max-power-engine: the maximum power of the engine, in kW.
engine-prop-factor: the engine is working as a pd-regulator. This
is the width of the regulation-band, or, in other words,
the inverse of the proportional-factor of the regulator.
If you set it to 0.02, than up to 98% of the rotor-rpm
the engine will produce maximum torque. At 100% of
the engine will produce no torque. It is planned to use
YASim-engines instead of this simple engine.
engine-accel-limit: The d-factor of the engine is defined as the
maximum acceleration rate of the engine in %/s,
default is 5%/s.
max-power-rotor-brake: the maximum power of the rotor brake, in kW
at normal rpm (most? real rotor brakes would be overheated
if used at normal rpm, but this is not simulated now)
rotorgear-friction: the power loss due to friction in kW at normal
RPM
yasimdragfactor:
yasimliftfactor: the solver is not working with rotor-aircraft.
Therefore you have to specify the results yourself.
10 for drag and 140 for lift seem to be good starting
values. Although the solve is not invoked for aircraft
with at least one rotor, you need to specify the cruise
and the approach settings. The approach speed is needed to
calculate the gear springs. Use a speed of approx. 50knots.
They do not need to match any real value.
The rotorgear needs a <control> subelement for the engine
(ROTORGEARENGINEON) and can have further <control> subelements:
ROTORBRAKE: rotor brake
ROTORRELTARGET: the target rpm of the engine relative to
the "normal" value for the governor. Default is
1.
ROTORENGINEMAXRELTORQUE: the maximum torque of the engine
relative to the torque defined by the engine-
power. Default is 1. By setting the rel-target
to a large number you get control over the
engine by this control.
Alternatively you can use these two values for
individual start-up sequences (see the s58)
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