Freighter in Your Campaign

[vanir]

Test bed is what I mean by technology demonstrator. It's like the way the Eagle A to C upgrade might've tested the newer F-15C radar on a modified DC4 and the engine management changes on a modified F-16 so the actual changes don't appear on the Eagle until production of the newer version. The basic design itself is already proven and doesn't need prototypes, which are dangerous because you put a bunch of new untested systems in the one aircraft without knowing if they work, then once you know they work it can go full production because the basic design is already tested in the earlier version. Cuts cost, raises development safety.

So the TIE advanced represent technology demonstrators, ie. test beds, the changes are tested in those then just incorporated into mass production changes without the expense of more prototyping, a preproduction series and service evaluation consistent with entirely new types.

After the test series for Interceptor changes to the TIE, the modified TIE advanced prototypes can be reconfigured for other projects too, so there's no waste. The same TIE Advanced craft might have shields installed one month, then deleted another and hyperdrive installed, then that deleted later again and a quad laser system trialled on it, all on the same individual craft.
The TIE interceptor prototyping worked more like that I'm saying, which is actually described in some published material I know I've read before which discussed the TIE bomber/shuttle project and TIE development. Some of my ideas were based on that.

Not necessarily how it works best in your campaign, but I like trying to emulate engineering/production conventions I'm familiar with in our game so there's always a consistent mechanic the players can become accustomed to.