This is all a bit confusing, because the 1940s engine room photos show a facility that's not all that different from the STXI one. Exposed pipes and naked supports are all the vogue, while control panels are scattered here and there instead of covering all the walls.
It almost seems as if Jeffries completely dropped the ball originally, and later generations had to correct his mistakes...
Granted that vanity covers will probably increase in number and coverage when reliability of the tech beneath improves - eventually giving us something like the TNG engine room. But the trend in control panels is one of diminishing size, because controls become more and more abstract and do not have to be built into the same giant cowling where the machine itself resides.
Also, the exposed brewery looks ergonomically superior to the model where all important machinery is hidden behind panels, and those panels in turn are hidden in really awkward corridors or crawlways. Granted that TNG got exceptionally bad with the all-fours Jeffries tubes - but as the name implies, Matt himself was the first to introduce this idiocy, and in an absurdly tilted configuration to boot.
Timo Saloniemi
The thing with the Hornet's engine room is that we're talking about a STEAM-POWERED SYSTEM.
For those who aren't familiar with how power is generated in modern terms... here's a primer. For those of you who already know this stuff, feel free to skip ahead.
All major power generation today is done by conversion of heat energy into mechanical energy and then conversion of that mechanical energy into electrical energy. In the case of windmills and hydroelectric power, you can take out that first step, and in the case of photoelectric generation or electrochemical generation (in the form of fuel cells), you're doing something totally different. But the overwhelming majority of all power generation follows the pattern I just described.
Basically, the first step is generation of heat. This can be done by burning fuel, or by having a controlled nuclear reaction, but it's really all about heat generation.
This heat then converts a fluid (normally ordinary water) from liquid into gas. The process of going from liquid to gas means that the material expands tremendously in volume. This volumetric expansion is the fundamental element which makes this useful - you expand liquid water into steam, and it "pushes" through a turbine, converting the heat into rotational motion.
This rotation then turns a generator, which is essentially (and dramatically oversimplified, mind you) a magnet turning inside a coil of wire, "pushing" electrons along the wires. This electrical flow is what we see as usable power.
That's everything we do today. Virtually all power generation on the planet, even today, is "steam power." I find it fascinating that so many people think that the "Spiderman II" version of power generation makes sense... somehow using "magic wands" to collect energy directly. As of today, it doesn't work that way, and we have no idea how to do things in any other way.
But... by the 23rd century, if we have matter/antimatter reactions driving faster-than-light starships, I'd sure as hell hope we'll have come up with a better approach than "use the m/am reaction to heat water, converting it to steam and turning a turbine to drive a generator set."
The "plumbing" you see in the Hornet is there because that ship is carrying steam through those pipes. The shut-off valves you see are there to block or open paths for steam to flow through, or for liquid water to flow through, or for lubrication to the turbine and generator bearings.
If you accept a modern model of what an engine room should look like, you're accepting that this ship runs on steam power, at FTL speeds.
I find that... dubious, at best.
But the "Abrams-prise" engine room is worse than that. Because the containers, the "plumbing", all that... in the brewery, it's clearly and unambiguously LOW PRESSURE DESIGN. That's the big difference between, say, the Hornet's engine room and the brewery. The modern naval engine room has extreme-high-pressure pressure-vessels, extremely robust "plumbing" and valving and so forth... and pressure gauges and so forth throughout to ensure that people working in there can tell if there's a problem in the steam system.
In the brewery, you have what are essentially unpressurized systems... only subject to "pressure head" due to gravity (and many orders of magnitude lower than that which you see in a steam-based generation system).
SO...
What we see in the "Abram's Enterprise" engine room is a low-pressure tank system, with no heat generation, no lubrication system, just lots of low-pressure fluid-managment hardware. Just big beer casks and "taps" on those "kegs."
