Here are some things I've added to the submodel code.
First, I added a first_time value that is true when the trigger is pressed and
false when the trigger is released. The true value is also made false after
the first pass through release(). Release() then uses this to force the
first dt (per salvo) to be zero. I was hoping this would make the submodel
appear closer to the airplane, but I don't notice a difference with the
tracers. In a prior test I found that the first dt is about 2.5 times larger
than subsequent ones. Maybe this will be effective with slower submodels,
like smoke, contrails, etc.
Secondly, I updated the IC.elevation and IC.azimuth calcs to correctly add in
the yaw and pitch offsets, corrected for bank angle. Actually this is still
an estimation. A proper calculation will sum the submodels vector with the
airplane's vector. Until that's done only models which are fired forward
will have proper IC.