Re: [Flightgear-devel] JSBSim - how to model piston engine exhaust thrust?

[Jon S. B. <jon...@co...>]

> Hi again :)
> 
> The jsbsim piston engine uses the propeller model for thrust
> calculations, so
> in and of itself, it can't model exhaust thrust.
> 
> My first though for modeling this extra bit of thrust is to add a pair
> of
> equations in the <aerodynamics> <drag> and <lift> sections.  Perhaps a
> table
> based on manifold pressure and/or horsepower output?  Multiply the drag
> section by -cos(alpha) and the lift section by sin(alpha) to get the
> thrust
> to line up with the aircraft longitudinal body axis.
> 
> Ron

Ron,

What's your second thought?

Here's one: I'm going to be adding support for specification of arbitrary
functions in engine and propeller definitions. I'm thinking that this should
permit functions to be specified that would allow a force value to be
calculated, then used in the external forces section to apply the force at a
particular area.

Sound good? It would require the resolution of our property
declaration/definition problem. But, that will be resolved.

Jon