A 50 kiloton Missile Cruiser, Ceramic Composite / Magneto-Plasma

[nuclearslurpee]

I don't have the link on me, but rule of thumb is that (regardless of boost level and engine tech), a given range/speed combination is achieved with minimum mass by having 3x as much engine as fuel. You are waaay off that ratio.

Shameless self-promotion  .  Note that while 3:1 ratio of engines to fuel is performance-optimal, A larger ratio of engines is usually more fuel-optimal, which makes logistics a lot easier. Given that these engines are running at 75% EP modifier (reverse-engineering from the EP and explosion% stats), it seems that the OP is going for fuel efficiency.

On the other hand, for the same total engine mass a design with fewer, larger engines will always be more fuel-efficient, but those larger engines do have drawbacks in terms of research costs, HTK, and I believe MSP consumption as well. OP has 5 x MP-1200 Drives @ 0.75 modifier which means each one is size 100. More efficient configurations would be 4 x size 125 or 2 x size 250, however as mentioned these would be more expensive to research. Additionally size 100 is the maximum of a tech level, so another tech is also needed which may not be viable in OP's game situation.

That said, I agree with other assessments that fuel efficiency for a large warship like this is not so critical and I would probably suggest 4 x MP-1600 (size 100, EP modifier 1.0) instead which gives a slightly higher speed (6400 km/s, which is more in line with MP era as 6000 km/s is a bit slow) while freeing up more tonnage space for other suggested improvements.

PD analysis: beam weapons have ~100% chance to hit in final fire against a target at their tracking speed (its a bit less, but crew and CO bonuses exist so I round up). Thus, a weapon effectively has a speed capacity to kill. 1 shot at 10,000 km/s tracking can stop 1 10,000km/s target or half a 20,000km/s target.

Thus, the PD threat of a missile volley is its speed*number of missiles. You have 20 missiles at 16,000km/s, so 320,000km/s capacity is needed to stop them all.

A 10cm railgun is 4 shots/150 tons. At 6000km/s tracking, you need 54 shots to stop all 20 missiles. You can get that with only 14 railguns, massing all of 6000 tons.

Because of PD/AMMs, it is rarely a good idea to optimize purely for hit chance as you will need extra speed (at the cost of hit chance) to defeat PD and AMMs. My personal missile optimizer is configured to maximize the product of accuracy and speed (i.e. speed squared times maneuver rating). 16,000 km/s is much too slow especially when you can design AMMs that fly more than 3x as fast. I'd try to get my ASMs to be at least 50% of my AMM speed if not closer to 2/3.

[Jorgen_CAB]

Another fact with engines is that they are quite expensive to research so you might need to use them in many different hull types that need a varied amount of range. Also... fuel efficiency are never completely unimportant but in general one of the least important factor.

As long as we know that the optimal engine to fuel ratio is 3:1 everything else we do different to that is making an informed choice between different factors and risks.

As I often play my games with a research efficiency of 10-20% (in addition to other restrictions) a particular engine can take many years or sometimes as much as a decade to research depending on size and cost, that will make you consider compromises quite often.

We then have the general situation a particular scenario plays out in, this should heavily influence how and what ships and components you build and why.

[misanthropope]

mass isn't a scarce resource, and it doesn't even associate all that closely with scarce resources.  effectiveness tends to increase with application of scarce resources, but with diminishing returns.  accordingly, when we optimize for "effectiveness at fixed tonnage" we ought to anticipate designs that are unduly resource-intensive.

[captainwolfer]

 

mass isn't a scarce resource, and it doesn't even associate all that closely with scarce resources.  effectiveness tends to increase with application of scarce resources, but with diminishing returns.  accordingly, when we optimize for "effectiveness at fixed tonnage" we ought to anticipate designs that are unduly resource-intensive.

I disagree. More mass means more cost, because you have to have bigger engines, more armor, more engineering, etc, to get the same performance.

[Jorgen_CAB]

mass isn't a scarce resource, and it doesn't even associate all that closely with scarce resources.  effectiveness tends to increase with application of scarce resources, but with diminishing returns.  accordingly, when we optimize for "effectiveness at fixed tonnage" we ought to anticipate designs that are unduly resource-intensive.

I disagree. More mass means more cost, because you have to have bigger engines, more armour, more engineering, etc, to get the same performance.

You also need more maintenance facilities, larger yards, longer time to build the ship for the same mission tonnage. Time is also an important resource, population to man the things you need is also a resource.

In times of war it is far more efficient to pre-build expensive engines in factories to quickly get more powerful ships in the field. Overly large but fuel efficient ships are much slower to build due to its size.

The larger your ship is the more time we need to invest in their production but there are positives with big ships too of course, but they come later after a bigger investment in time.

[sadoeconomist]

Isn't the ship extremely short on ordnance capacity? If you're going to use standard-size ASM launchers, well, box launchers are 15% of their size, so if you've got fewer than 7 salvos worth of missiles onboard, it doesn't make a lot of sense to not just use box launchers, save some space, and be able to launch all your missiles at once. 90 box launchers is 2700 tons compared to the 4000 tons of 20 standard launchers, which also require 240 crew to man them, plus magazines. Even .3 launchers would be able to launch nearly all your missiles while staying in the same tonnage, and they could be reloaded from colliers instead of needing an ordnance hub. AMM launchers with only 4.5 salvos, too - you could launch all 180 of your AMMs before the first incoming salvo is even halfway through your launcher's envelope. You could cut 25 AMM launchers (along with another 125 crew) and still launch everything before anything traveling at your ASM's speed touches you. And even then, you'd only have the ammo to defend against a single ASM salvo, and then you'd be left with your pants down. Much of the tonnage taken up by those MLs is basically dead weight without the magazine space to back them up.

Also, is this meant to work totally independently or as part of a fleet? If it's part of a fleet then it can offload much of its fuel & MSP capacity to tankers and supply ships to fit more payload, and the engines could be boosted and reduced in size to add even more combat capability while keeping its speed high. And there's not much reason to put AMMs and ASMs on the same ship class instead of specializing. If it's going to function independently (as a scout? a commerce raider? what could it really do solo?) then it probably needs better sensors, some beam PD, and a jump drive. A ship that can run through all of its offensive ordnance in 75 seconds and then be left completely toothless isn't a good fit for an independent long-range ship though - it needs support from an ammunition transport at least, and if you're giving it one support ship you might as well give it the full set. It'd work better independently if it had a primary beam armament instead of the ASMs - then it could go on a long-distance cruise, kill multiple targets along the way, and be able to defend itself while heading home for an overhaul.

My rule of thumb for maintenance costs is to shoot for about 10% AFR for each 1000 tons, and at 400% AFR for 50000t this ship is a little heavy on engineering spaces, but if it's also got a chief engineer then its AFR will be even lower. Also, if its AFR is 400% and it deploys for 9 months, it's likely to have about 3 breakdowns per deployment, and its max repair is 450, so the MSP requirement is about 1800 for a worst case scenario of only your most expensive components breaking 1 more times than expected. It's got almost 6 times that much MSP capacity onboard though. In reality it probably won't even use a tenth of that, especially with a skilled chief engineer - there's no reason for it to be carrying anywhere near that much MSP.