AISim uses a 6-degree of freedom, linear coefficient resolver model.
All units are imperial.
The aero reference point is always located at (0.0, 0.0, 0.0).
Center of gravity is relative to the aero reference point.
All other positions are relative to the center of gravity.
Positions are in inches and in the JSBSim structural frame:
X is positive aft
Y is positive right
Z is positive up
Up to 4 engines and up to 4 gear positions (contact points) can be defined.
AISim always adds an extra contact point at the aero reference point.
Configuration files are in JSON format.
Any parameter which is omitted is set to zero.
AeromatiC++ version 3.3.12 or later also outputs to AISim JSON format.
An example of a configuration file for the Cessna 172p is given below.
Note that JSON does not support comments. So the semicolon and text following
it in this example are just for clarity and should be removed or omitted when
using it with AISim.
=============================================================================
{
"c172p" : 1.0, ; name and version number
"Sw" : 174.0, ; wing area (ft2)
"cbar" : 5.3, ; root chord (ft)
"bw" : 35.8, ; wing span (ft)
"mass" : 2300.0, ; mass (lbs)
"Ixx" : 948.0, ; inertia along the x axis (slug*ft2)
"Iyy" : 1346.0, ; inertia along the y axis (slug*ft2)
"Izz" : 1967.0, ; inertia along the z axis (slug*ft2)
"Ixz" : 0.0, ; inertia along the xz axis (slug*ft2)
"cg" : [ -2.4, 0.0, 22.9 ], ; CG relative to AR (in)
"engine" : [
{
"pos" : [ -78.7, 0.0, 22.9 ], ; enginge pos relative to CG (in)
"dir" : [ 0.0, 0.0, 0.0 ], ; thruster direction (degrees)
"FT_max" : 615.6, ; max thrust at sea level (lbs)
"MT_max" : -37.3, ; max thruster torque (lb-ft)
"rpm_max" : 3002.1 ; max propeller revolutions per minute
} ],
"gear" : [
{
"pos" : [ -90.3, 0.0, -56.7 ], ; gear pos relative to CG (in)
"spring" : 690.0, ; gear spring factor (lbs/ft)
"damp" : 345.0 ; gear damping factor (lbs/ft/sec)
},
{
"pos" : [ 5.3, -38.7, -56.7 ],
"spring" : 2300.0,
"damp" : 1150.0
},
{
"pos" : [ 5.3, 38.7, -56.7 ],
"spring" : 2300.0,
"damp" : 1150.0
} ],
"de_max" : 17.5, ; max elevator deflection (degrees)
"dr_max" : 20.0, ; max rudder deflection (degrees)
"da_max" : 20.0, ; max aileron deflection (degrees)
"df_max" : 40.0, ; max flap deflection (degrees)
"CLmin" : 0.31,
"CLa" : 5.143,
"CLadot" : 1.7,
"CLq" : 3.9,
"CLdf" : 0.4000,
"CDmin" : 0.031,
"CDa" : 0.1581,
"CDb" : 0.17,
"CDi" : 0.054,
"CDdf" : 0.0300,
"CYb" : -0.31,
"CYp" : 0.037,
"CYr" : 0.21,
"CYdr" : 0.187,
"Clb" : -0.089,
"Clp" : -0.47,
"Clr" : 0.096,
"Clda" : 0.178,
"Cldr" : 0.0147,
"Cma" : -0.89,
"Cmadot" : -5.2,
"Cmq" : -12.4,
"Cmde" : -1.28,
"Cnb" : 0.065,
"Cnp" : -0.03,
"Cnr" : -0.099,
"Cndr" : -0.0657
}
