[Jsbsim-devel] Multi-body modeling

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

As you may know, I've been interested in modeling multiple-bodies in JSBSim
for some time. There are references to child model objects in the codebase,
now. I've been wondering, however, if there is a better way to do this. It
occurred to me that perhaps just having multiple instances of JSBSim running
would work, where a state could be passed from the "core" instance, to other
instances. This is not dissimilar to the way I have been considering
implementing the capability, with the difference being in what object is
responsible for managing the various instances of JSBSim.

A reference case for such a capability is for a multistage rocket. We do
have an example case that is being developed, now (the J246). However, once
bodies (such as booster rockets) are dropped off they are not tracked. I
simply zero out the mass of the spent boosters. However, what if instead we
initialized an instance of JSBSim for each booster rocket that is dropped?
The way that might work is to actually create an instance of JSBSim
representing each booster rocket (or each individual piece). The initial
configuration of the rocket would be done as it currently is in the J246
model, where the monolithic rocket is modeled. However, at staging, if the
mass of the booster rockets is zeroed out, I envision that at that time we
can initialize the "dormant" JSBSim instances that represent each booster
rocket by itself at the current correct location, and let them fly free.
This would, of course, require the application that manages a JSBSim
instance to be set up to handle multiple JSBSim instances. However, I think
this could be made to work.

Thoughts?

Jon