On Samstag, 24. April 2004 21:31, Andy Ross wrote:
> It's a misfeature in the gear modelling. YASim has pretty much the
> same behavior. Both FDMs model gear force as a function of "skidding
> velocity", which is fine for dynamic solutions. But a gear that is
> planted on the ground is capable of "holding" an aircraft at zero
> velocity, which doesn't work with the current FDMs -- zero velocity
> produces zero force.
>
> What's needed is code that, at low speeds, uses a spring model for
> gear force based on the distance in position from where the gear is
> "stopped". Which sounds easy, but in practice is awfully hard. I've
> gotten started on this several times, and never produced useful
> code.
Yep, kind of true.
Jon and I are working on a solution to this. At least for JSBSim.
It is not only the gear modelling which plays a role here, the time
integration of the equations of motion play a role too.
There is code on a development branch in JSBSim's cvs which addresses this and
also works well so far.
And Andy, If I remember right, I believe that it was a comment of you about
the problem beeing stiff, that made me look into JSBSim's timestepping ...
;)
Greetings
Mathias
--
Mathias Fr�hlich, email: [EMAIL PROTECTED]
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