ok
void geometry_batcher::draw_bitmap(vertex *pnt, int orient, float rad, float angle, float depth);
int g3_draw_rotated_bitmap_3d(vertex *pnt, float angle, float rad,uint tmap_flags, float depth);
as we see here to maintain the same behavior between these two versions the angle and radius values need to be swaped.
here is the problem, it would seem the radius scaleing factor was put on the wrong parameter in the earliest version of the thruster effect, not when it got ported over to the geometry batcher. the default value for this scaleing factor is 1.0, so it has no effect unless it is specificly changed, and if you tried to change it all you would likely notice is nothing happened (the angle probly wouldn't jump out at you unless you were looking for it, also this is a little known feature, so I doubt many have tried) so, I think the way to handle this should be to put the two parameters back the way they were, and move the scaleing factor over to the corect parameter. this would put the effect back into the same basic behaviour that we have been used to for the majority of it's life
magnatude is based on the normalization of the thrust vectors, and is thus never more than 1, so the current code will draw the glow with a radius of only 0-4, no mater the size listed in the pof, or the size of the model.
obviusly 0-4 makes more sence as something that would have to do with radians, and w (wich is a scalar of the thruster point size) would make more sence as the radius of the glow.