Battleship Yamato

[jageriv.rodan]

Well, I've finally unlocked module design. To celebrate and get some practice in, I've decided to unambitiously model the battleship Yamamoto.

Initially, this will just be the "stock" battleship. Basically, I'm going to be using just conventional guns, rather than fancy rails or lasers. Just trying to recreat, sorta, the weapons it actually had. So I can get a feel for the conventional cannon creation system.

Thus, armament at this point is intended to be:

9 46 cm guns with a muzzle velocity in the 800 m/s range with a large shrapnel or explosive based warhead.

6 15.5 cm guns with a muzzle velocity in the 900 m/s range with a large shrapnel or explosive based warhead.

24 127 mm guns with a muzzle velocity of 700 m/s with bursting charges

162 25 mm guns with muzzle velocity of 900 m/s with very small bursting charges (this one may be halved or thirded, since so many were double or triple mounts)

4 13.4 mm machine guns, 800m/s, solid projectile.

Armor will be primarly 400 mm with armored compartments/modules. Going to try and use the closest thing to the kind of armor they would have used, once I figure out what that is.

Target dry weight is about 50,000 tonnes. This may demand a total mass with full fuel tanks of 150,000. I'll have to see how that goes. Length however should be about 250 meters.

I'm probably going to have to design new engines to move this thing regardless. I'm thinking of trying using water, because I think it's the most dense fuel available, and because boat, but I might just stick to the methane I'm more familiar with.

So, that's my goal, and I'll post pictures of my progress, discuss anything I learn, and beg the rest of you for help.

First up, of course, will be the big guns, because why else would you try making a battleship?

Which in this case probably mean first designing the shell.

Well, wish me luck.

[Dog]

If you don't care about acceleration, you can go with 20m diameter mercury plasma thrusters.
I build a ship with nearly 80km/s deltaV, 469 kN of thrust and little over a day burn time. And that's with 1.5kt of mercury.

If you know how to build high temperature compact nuclear reactors (See official forum thread), they're one of the best choices for capital ships. For in-battle manoeuvres you can use high thrust fluorine-methane directional thrusters (hydrogen takes up more space) or hydrogen deuteride nuclear thrusters.
Sub 1km/s velocities are also pretty slow, and without nuclear payloads your projectiles will be expensive if you want to do any damage.

[jageriv.rodan]

And almost immediately, I seem to run into the problem where I can't seem to select the payload I wan for my guns. Is there anything special one has to do to let you put the payload you want on a gun?

[brad]

You should try carbon steel for the armor, battleships also had varying armor thickness all throughout their structure, so you could place a few extra layers over the powerplant, crew modules, and ammunition storages. Just use the start/end to restrict the area they armor.

[jageriv.rodan]

As a clarification, it does not seem to recognize my custom shrapnel payload as an option to put in my gun.

Is this just a bug, or is there something I have to do to get a custom payload on the list of payloads I can actually deploy?

[brad]

You need to go into ship designer, payloads, then make a new payload, set down your custom one and save it.

[jageriv.rodan]

Hm, I've done that, and I see my custom payload listed in the payload list from the module editor, but when I go in and try to edit the gun, there is still only one "flak" option which is clearly not the one I'm looking for.

Right now, the gun creation module seems like it can only reconize one type of flak being viable for sticking on the gun, despite there being 3 different flak payloads in the payloads section. I'm not sure what I'm doing wrong here, or if I'm even doing anything wrong.

[Zarincos]

Ah, yeah, it's a bit awkward, you made a flak payload, but to be loaded as a payload into a gun it needs to be a ship of type "payload". If you go to the ship editor you should be able to see the payload section, which should be different than the payload modules. I think you might be able to just make a new ship, add your payload and call it a day. I honestly have very little idea why some of the payloads have remote controls, for instance, and some don't.

[Darth Dinkerino]

Damn it you beat me to the answer by 1 minute.

[jageriv.rodan]

First, thanks for the help on figuring out payloads. It makes sense now that I've seen and played around with it, but that's definitely not how I would initially think to work it. Now,

Progress Update: designing the 46 cm gun.

Part 1: The Payload Module

So, as part of designing the Yamato gun, I first needed to make the fragmentation payload. It was at this point I found out the sliders don't actually let you model a single 1 tonne fragmentation warhead. So, I did the best I could below:

http://steamcommunity.com/sharedfiles/filedetails/?id=774702928

I used Iron because it was cheap, same with using Nitrocellulos. 90% iron, 10% explosives. I have no idea if that is optimal or not, and would appreciate anyone's opinion on it. Shape was so it can fit in a 46 cm gun, and I also have no real idea whether or not the shape makes sense or not.

It produces about 3,000 30 gram shrapnel pieces, which sound's deadly, though I'll have to test it as some point. Not really sure yet how to interpret the "shrapnel at hit" graph.


Part 2: The Payload Ship

So, time to create the actual payload that will go in the gun. Here I was able to fix the problem of the shell being too light: by putting more in: 9 in total.

http://steamcommunity.com/sharedfiles/filedetails/?id=774702775

So, theoretically this thing should now produce 27,000 30 gram fragments, assuming the game doesn't model the fragmentation of the actual armored shell. If it does that could add some 300 kg to the existing 810 kg of shrapnel.

If the round works as expected, it should have large enough fragments to do serious damage to the enemy ships if they manage to hit, though I'm not sure at this point if my computer could even handle one of these going off in real time. I'll just have to see how taxing this is.

View of the externals of the round:

http://steamcommunity.com/sharedfiles/filedetails/?id=774702819

Part 3: The Gun

This was the most chalanging, and where I realized how much I'll have to change from the actual design. Here's what I ended up with:

http://steamcommunity.com/sharedfiles/filedetails/?id=774702697

http://steamcommunity.com/sharedfiles/filedetails/?id=774707722

As you can see, some sub-optimal decisions had to be made. Rotation is slow, but the actual Yamato main guns had a rate of arround 5 degrees in real life anyways, so that's not a serious issue.

The gun weight, without any ammo or a turret, comes out to 300 tonnes. The historical Yamato 40 cm gun weighed around 160 tonnes. Some of this might be me not using the optimal material for the gun barrel or using the right propellant charge. Certainly there is more optimization I could do.

However, I think another major issue is how the game seems to model barrel thickness. It seems to assume constant thickness, which shouldn't be necessary since a gun like this has a fairly narrow location of peak pressure and a relatively long part of lever decreasing pressure. Thus, the barrel should be taper down as it goes, from a 36 cm to something much lower near the exit.

If the game is modeling things how I think they are, that could be adding 50 to 100 extra tonnes to the gun's weight, which cascades throughout the rest of the design.

The real concern however is the power necessary: 11.3 gigawatts of power to turn the guns. This seems far in excess of whatever should be necessary. It seems the turning wheel method employed in the model is a massive power hog. Also do to the way the turret is modeled, just making it bigger has major consequences: while with experimentation I can get power requirements down to about 1 gigawatt (still massive), the area to armor grows massively as well.

It really highlights the value of the historical turret design: you could have a very wide area to turn on for the turret, but then you could quickly elevate the gun up and down by moving it independently. This also let you keep the turret short, rather than this round way were doing it where the turret has to be as tall as it is wide.

But, that's just a reality of the game. I'll probably keep playing with it, see if I can get the power down to a reasonable level, and if one of you spots a way to optimize the gun better, let me know.

It's looking clear to me though that stock generators are going to be utterly insufficient for the ships power needs.

As a final note of the gun, I've noticed you can increase rate of fire almost arbitrarily. Given that, and the other issues, I'm thinking I might have one or two 46 cm guns with high rates of fire stand in for the 9 that were on the historical Yamato. Because there's no way I'm fitting 9 guns like this on a ship, and increasing rate of fire is just so utterly trivial in this game.

Maybe I'll do 1 5-6 thousand tonne turret with a rate of fire of 60 or so rounds a second.

[Cuddlefission]

The shrapnel hit graph is a bit tricky - it runs based on your set detonation distance, and then has the X-Axis plot speed of the shell relative to the target - with the size of the cloud upon target impact being the Y-axis result. It could probably use a log scale and be much more readable. Anyway, the trick with it is that, as of now anyway, the shells don't actually detonate at the place you specifiy - they seem to arm at that point and then try to blow at closest approach. So the utility of the graph is questionable, but it's neat in theory. As for the turret - I honestly wish they let you just put dedicated thrusters on the turret for rotations, because the scaling on the reaction wheels is so nasty.

[Cyborg]

Originally posted by jageriv.rodan:

The gun weight, without any ammo or a turret, comes out to 300 tonnes. The historical Yamato 40 cm gun weighed around 160 tonnes. Some of this might be me not using the optimal material for the gun barrel or using the right propellant charge. Certainly there is more optimization I could do.

You can use vanadium chromium steel as barrel meterial to reduce gun mass.

[Cyborg]

Originally posted by jageriv.rodan:

As a final note of the gun, I've noticed you can increase rate of fire almost arbitrarily. Given that, and the other issues, I'm thinking I might have one or two 46 cm guns with high rates of fire stand in for the 9 that were on the historical Yamato. Because there's no way I'm fitting 9 guns like this on a ship, and increasing rate of fire is just so utterly trivial in this game.

As a suggestion. You can make 3 turreted guns each representing a single Yamato turret. I.e. having x3 fire rate and mass of entire turret which is about 2700 tons according to http://www.navweaps.com/Weapons/WNJAP_18-45_t94.php#Mount/Turret_Data