I tend to keep Birth off to one side of my mind at all times. To some extent the entire project suffers from feature creep, but rather than the usual addition of more and more features, instead it's constant addition of depth to already planned features. A fair amount of this is just that I had never completely decided on the granularity of the simulation to begin with.
So for the last few hours, I've been whiling away the time reading about ion thrusters, and trying to decide on some sort of formal design for the engine of the space ship. Since no engines exist that exhibit the capabilities needed for our theoretical ship, this means a strange walk into "who the fuck knows" land, as I try and guess what parts a non-existent engine could possibly need. Some portion of this is obvious, there must be some form of reaction and some form of exhaust. Whether they are separated parts as they are in a car engine, or contained in the same space as they are in an ion engine is a bit of a hard debate. In large part, it works best if the only segment of the engine exposed to space is a single metal part much like the body of the craft. That way the functional segments of the engine are all available for on-site maintenance and repairs.
But significant questions must remain, does the engine produce the electricity or does it run off electricity? Does it require coolant? Is the reaction explosive in nature, corrosive, or expansive? An explosion would be more like a traditional rocket, it would require large amounts of fuel and also oxygen. Engine based off the basic Ion engine design tend to be highly corrosive to their parts, but require no oxygen and therefore can be very hot but will never explode. Expansive on the other hand gains force from the rapid expansion of a gas in a contained space with release in only the intended direction of force, which can be a pretty low maintenance but fuel expensive method. Technically the first and third methods are almost exactly the same, since an explosion is simply the hot and violent expansion of a source fuel. Perhaps a super high pressure containment unit which leaks a small amount of high explosive material into a blasting chamber would be the ideal form of those two.
The underlying model of the Ion engine on the other hand is high maintenance, ultra low (compared to rocketry) thrust, but super fuel efficient which allows for greater top speeds since it can run significantly longer. Most importantly though, although the engine itself is fuel efficient in terms of momentum/L, it requires an outside source of electricity in order to run. This brings a whole new barrel of monkeys to the field, should it be supplied by batteries, a motor, or a miniature power plant? It would be very understandable for larger ships to feature nuclear reactors, but what are the limitations to that? Should all big ships have nuclear reactors or only military ships? Could this mean a bunch of ships with really big standard ICEs?
Of course, if I was purely interested in making a narrative based game based entirely around piloting this would hardly matter. But since the beginning birth was intended to be largely simulation. Partly because without these levels of simulation it would be impossible to ever play the part of an engineer like Kaylee for instance. Perhaps I'm very strange, but I think it would be fun to see how long and how well you could keep a ship running on a shoe string budget.