Re: [Jsbsim-devel] Multiple property tree problem/soution

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

> On vendredi 26 juin 2009, Jon S. Berndt wrote:
> > I think you are missing the point. Multiple FDMs would be designed to
> work
> > within Flightgear or standalone.
> 
> Yes and .....NO :)
> How FG will be able to manage several multiple FDM ?
> OR, how the user/developper will be able to tell to FG which FDM must
> be in use ?

FlightGear would not know the difference - this is not a FlightGear
capability. Multiple FDMs would be managed and run using JSBSim features.
There is no difference between a single FDM and multi-FDM with JSBSim as far
as FlightGear is concerned. The base aircraft will always be the base
property tree - the first property tree. Let's say that the aircraft is the
B-52 carrying the X-15. In the B-52 there may be a switch that tells a
JSBSim system to drop the X-15. At that point, the X-15 would begin flying
(the integration of the X-15 Equations of Motion would start). Obviously,
there would need to be a way to link up a 3D model with a specific child
flight model, but I don't expect that would be a major issue.

I expect that for the near term (and I use the word "near" as a joke, since
this multi-body capability has been in-work for many years), I expect
FlightGear would not use this multi-body capability. I think it would be
mostly a JSBSim batch mode feature. I'd like to see it used for multi-stage
rockets, too, for instance.

The challenge is to make sure that FlightGear is not adversely affected by
the inclusion of this capability. I think Ron's suggested fix does that.

Jon