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JSBSim Aerodynamics: Difference between revisions
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→Effects: Talk about forces and moments due to control surface deflections.
(→Effects: Talk about forces and moments due to control surface deflections.) |
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* '''Aerodynamic Reference Point''' - JSBSim provides a way to shift the aerodynamic reference point (AeroRP) forward (negative values) and aft (positive) in response to mach, pitch or other influences. Use the tag <aero_ref_pt_shift_x> in the <aerodynamics> section. The value this tag function returns is internally multiplied by the chord entered in the <metrics> section to get the final shift. You could use this by setting the AeroRP to the leading edge of the wing and use a 1D table indexed by mach starting at .25 chord and getting bigger as the mach number increases to simulate mach tuck. | * '''Aerodynamic Reference Point''' - JSBSim provides a way to shift the aerodynamic reference point (AeroRP) forward (negative values) and aft (positive) in response to mach, pitch or other influences. Use the tag <aero_ref_pt_shift_x> in the <aerodynamics> section. The value this tag function returns is internally multiplied by the chord entered in the <metrics> section to get the final shift. You could use this by setting the AeroRP to the leading edge of the wing and use a 1D table indexed by mach starting at .25 chord and getting bigger as the mach number increases to simulate mach tuck. | ||
{{JSBSim}} | {{JSBSim}} | ||
^'''Lift Due To Elevator""" - There are two interrelated effects from elevator deflection, the Force change and the Moment. These have two different coefficients in two different sections of the FDM but should be considered together. The formula is: | |||
CLde * lh-ft = Cmde * cbarw-ft | |||
That is, the force (lift) created by the elevator times its length from the CG is equal to the moment. For some reason standard aerodynamics uses the chord as the reference length. | |||
A similar formula: | |||
CYdr * lv-ft = Cndr * bw-ft | |||
Is applicable the rudder's side force and yawing moment. The force (side) created by the rudder times its length from the CG is equal to the moment. For some reason standard aerodynamics uses the wing span as the reference length. | |||