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Maik JUSTUS: documentation for aerotowing parameters

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mfranz 2007-01-17 20:57:22 +00:00
parent 9fd4bd2aa8
commit 33b143b95a
1 changed files with 67 additions and 13 deletions
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Docs/README.yasim
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@ -44,6 +44,15 @@ fuselage: This defines a tubelike structure. It will be given an even
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
@ -288,10 +297,22 @@ actionpt: Defines an "action point" for an enclosing jet or propeller
x,y,z: The location of force application.
gear: Defines a landing gear. Accepts <control> subelements to map
properties to steering and braking.
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 considured 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 reuce numerical problems (jitter))
Note: the spring-constant is varied from 0%
compression to 20% compression to get continous
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
@ -312,6 +333,35 @@ gear: Defines a landing gear. Accepts <control> subelements to map
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"
inverse-speed-spring-is-doubled: At this speed (the inverse of
the speed must be given) the spring constant
is doubled. The idea is, to use this on water to
simulate the speed dependend lift of a float.
Defaults to "0"
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 equalt to 1. THe diea 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.
x,y,z: The location of the mount point of the launch bar or
@ -469,6 +519,9 @@ rotor: A rotor. Used for simulating helicopters. You can have one, two
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/)
@ -481,7 +534,6 @@ rotor: A rotor. Used for simulating helicopters. You can have one, two
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.
The torque property has a bug.
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)
@ -555,24 +607,20 @@ rotor: A rotor. Used for simulating helicopters. You can have one, two
is stall. In the range between this incidences it is
interpolated linear.
The airfoil of the rotor can be described in two ways. First you
can define the needed power for different pitch values and the
total lift force at a user-defined pitch value. Don't use pitch
values greater than the stall incidence. You could get strange
results.
pitch-a:
pitch-b: collective incidence angles, If you start flightgear
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:
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;
@ -626,6 +674,8 @@ rotor: A rotor. Used for simulating helicopters. You can have one, two
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
@ -653,7 +703,7 @@ rotor: A rotor. Used for simulating helicopters. You can have one, two
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-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
@ -688,7 +738,11 @@ rotorgear: If you are using one ore more rotors you have to define a
yasimliftfactor: the solver is not working with rotor-aircrafts.
Therefore you have to specify the results yourself.
10 for drag and 140 for lift seem to be good starting
values.
values. Although the solve is not invoked for aircrafts
with at least one rotor, you need to specifiy the cruise
and the approach seetings. 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 a <control> subelement for the