New kinds of PDCs

[BeeDee10]

Now _this_ I _love. It has never made sense to me that the exact same engine module can propel a 150Kt spacecraft at the same speed and with the same resource consumption as a 1.5Mt monster. The _scale_ shouldn't matter in space flight, it's all about the proportions. Differentiating engine efficiencies makes sense too, to allow for slow-and-steady long haul arks and overmuscled in-system defence frigates.

Is this system going to be made into a mod, or is this merely a theoretical description left up to the reader to implement?