Hello Tomgeneral, hope all is well with you.
I have only taken complete scenes out from Blender to Gmax, nothing that used a hier, the tutorial I used was not built around a hier
as it was not intended for IL-2 it was just meant to show the build and texture of that vehicle.

On from that, you can export a single mesh or the whole scene to a 3ds file using Blender, what determines what is there in that file
is whether you have parts opened in the window or not, any turned off will not be in that 3ds you export as far as I can tell from what
little experimenting I have done so far.
To open the 3ds in Gmax use the right hand panel, first open the listener and clear it of any text, you will use
the fields in the MAXScript box:

Use the 3ds import button to find your saved 3ds file, mine save in the documents folder:

Once you click on the import button your listener will fill with text:

Sometimes you will also get error messages pop up, ignore them and click anywhere on the screen:

Clear the listener again of text and your model import should be there:

That is about as much help as I am able to provide sorry to say, my imports from Blender have been
limited and to be honest even when I built my Lysander in Gmax there was no hier in there nor did I
Know how to create one in the program, I do not know how to create one in Blender either.

Once your meshes are in Gmax you will need to weld them all up again even if they were already
done in Blender, at least that is what I found with what I worked on, I might have done something
wrong, who knows.
I tend to extract things out a mesh each time once in Gmax and have a hier set up in the folder where
I put the extracted meshes and mat and texture files for each mesh, I build slowly from there a bit at a
time adding as I go.
The only people I know who have exported Il- 2 models from Blender into Il-2 are Dandolo, Tvister and Zflyer,
I don't know if they just export into MshConverter complete or even into Gmax via a 3ds file.
Sad to say that is as much as I am able to offer in regard to getting your project into Il-2, if you find a good way
then please let me know how it is done I would like to know just what and how is the best way.

Take care and be safe.
Wishing you all the very best, Pete.
