diff --git a/Docs/README.yasim b/Docs/README.yasim index e98529d40..50d26db4c 100644 --- a/Docs/README.yasim +++ b/Docs/README.yasim @@ -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 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 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 subelement for the engine (ROTORGEARENGINEON) and can have a subelement for the