Time to make a start on airfields, now that I have most of the information needed.
The existing generic field at Calais-Marck is historically incorrect and will need to be redone, but I've decided to start with an unimportant small field in the east at Montcornet, near Sedan.
This shows the basic ground template set up in my temporary map. Montcornet was an emergency field set up in 1938 and was essentially a grass strip with limited facilities, typical of many small field in Northeast France, prior to further expansion by the Luftwaffe.
A mini tutorial on how to set up these templates is provided here -- viewtopic.php?p=30459#30459
The template is a special tiled area 3200x3200 metres in size. Any 16bit tga image, 1024x1024 pixels can be used.
Because the game engine overlaps the tiles they tend to become "burned out" (all white). This is prevented by reducing the brightness in the original image. In photoshop I applied -100 to brightness before importing the image.
The airfield model can be created in the temporary map and then cut and pasted into the master map. The template allows you to accurately position all the airfield objects, but make sure that north is at the top of the map (if that is how your game map is aligned) and that you have the scale adjusted correctly.