[Atraikius]

Try giving each fighter a more unique role (i.e. use the small fighter as a cheep, fast to build interceptor, the the meadium as a strike fighter - slower, but armed with both a missile pod, and either a small DUC or small meason bLaster, and your large as your main fighter), ensureing that each has a different design name. Then instead of calling for fighter in the Construct_Vehicle file (still haven't gotten around to seeing if the Construct_Units file accepts design names, but you could try the same in that), use the design names of each. You will still have the smaller and older fighters, but you should have some control over the amount that are built, and the larger fighters should be built more often.

I would suggest setting the minimum tonnage on the larger two fighters to allow small fighters to keep from limiting your fighter construction before medium and large fighters are researched.