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Aero input and outputs: Difference between revisions
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→Function outputs: Added Alans note, and made some headings
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(→Function outputs: Added Alans note, and made some headings) |
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== Function outputs == | == Function outputs == | ||
Ground effect factors for lift and drag: | === Ground effect factors for lift and drag: === | ||
/fdm/jsbsim/aero/function/ground-effect-factor-lift | /fdm/jsbsim/aero/function/ground-effect-factor-lift | ||
| Line 110: | Line 110: | ||
the <aerodynamics> section of the configuration file (varies per-aircraft): | the <aerodynamics> section of the configuration file (varies per-aircraft): | ||
Lift coefficients: | === Lift coefficients: === | ||
/fdm/jsbsim/aero/coefficient/CL - Lift coefficient | /fdm/jsbsim/aero/coefficient/CL - Lift coefficient | ||
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/fdm/jsbsim/aero/coefficient/CLDflaps - Lift coefficient of flaps | /fdm/jsbsim/aero/coefficient/CLDflaps - Lift coefficient of flaps | ||
Drag coefficients: | Alan wrote about lift: | ||
Lift = qbar-psf x Sw-sqft x CL | |||
Lift is a force, CL is the non-dimensional coefficient of lift, qbar-psf x Sw-sqft is the dimensionalisation factor | |||
It is common practice to build up the lift force from several sources. | |||
e.g., for the Lift Axis | |||
Lift = qbar-psf x Sw-sqft x (CLwing +CLtail +CLelevator +CLfuselage +... +...) | |||
here the various lift coefficients are summed before being dimensionalised. | |||
or you can also write | |||
Lift(wing) = qbar-psf x Sw-sqft x CLwing | |||
Lift(tail) = qbar-psf x Sw-sqft x CLtail | |||
Lift(fuselage) = qbar-psf x Sw-sqft x CLfuselage | |||
.... | |||
Lift(total) = Lift(wing)+Lift(tail)+Lift(fuselage) +.... +... | |||
here the various lift coefficients are separately dimensionalised to produce a set of forces. These forces are then added to produce the total lift force. | |||
You can write CLwing = CLo + Alpha* dCL/Alpha, or alternatively use a table to generate CL as a function of alpha, Mach no etc. | |||
It is not necessary to slavishly follow the examples in the JSBSim reference manual, or copy other Flightgear examples. It is best to follow the conventions that apply to the data you have available. | |||
JSBsim allows you to specify these equations in any way that suits you, or suits the data that is available. | |||
One thing to be careful about is not including a component twice. e.g. the CL that you are given may already include the tail and fuselage effects, and this case they should not be added in again. | |||
=== Drag coefficients: === | |||
/fdm/jsbsim/aero/coefficient/CD - Drag coefficient | /fdm/jsbsim/aero/coefficient/CD - Drag coefficient | ||
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/fdm/jsbsim/aero/coefficient/CDDflaps - Drag coefficient of flaps | /fdm/jsbsim/aero/coefficient/CDDflaps - Drag coefficient of flaps | ||
Side force coefficients: | === Side force coefficients: === | ||
/fdm/jsbsim/aero/coefficient/CYb - Side Force coefficient due to Sideslip | /fdm/jsbsim/aero/coefficient/CYb - Side Force coefficient due to Sideslip | ||
| Line 141: | Line 173: | ||
/fdm/jsbsim/aero/coefficient/CYr | /fdm/jsbsim/aero/coefficient/CYr | ||
Roll moment coefficients: | === Roll moment coefficients: === | ||
/fdm/jsbsim/aero/coefficient/Clb | /fdm/jsbsim/aero/coefficient/Clb | ||
| Line 149: | Line 181: | ||
/fdm/jsbsim/aero/coefficient/Cldr | /fdm/jsbsim/aero/coefficient/Cldr | ||
Pitch moment coefficients: | === Pitch moment coefficients: === | ||
/fdm/jsbsim/aero/coefficient/Cmalpha | /fdm/jsbsim/aero/coefficient/Cmalpha | ||
| Line 159: | Line 191: | ||
/fdm/jsbsim/aero/coefficient/CmDsb - | /fdm/jsbsim/aero/coefficient/CmDsb - | ||
Yaw moment coefficients: | === Yaw moment coefficients: === | ||
/fdm/jsbsim/aero/coefficient/Cnb | /fdm/jsbsim/aero/coefficient/Cnb | ||
| Line 167: | Line 199: | ||
/fdm/jsbsim/aero/coefficient/Cndr | /fdm/jsbsim/aero/coefficient/Cndr | ||
Stall hysteresis, normalized: | === Stall hysteresis, normalized: === | ||
/fdm/jsbsim/aero/stall-hyst-norm | /fdm/jsbsim/aero/stall-hyst-norm | ||
Time rate of change in alpha and sideslip in deg/sec and rad/sec: | === Time rate of change in alpha and sideslip in deg/sec and rad/sec: === | ||
/fdm/jsbsim/aero/alphadot-rad_sec | /fdm/jsbsim/aero/alphadot-rad_sec | ||