June 15, 2020

Aurora Tutorial Part 12

So far in our discussion of Aurora, we've covered everything from the basics of combat up through command structures, but there's one thing that has been overlooked: logistics and the fleet train. Aurora, much like real life, has auxiliaries, and it's time to take a look at how those ships work.

But first, we need to take a look at the logistical needs of the ships. Essentially, a warship has four different things it can run out of: fuel, maintenance supplies (MSP), ammunition, and deployment time. Fuel is self-explanatory. Without it, ships don't move. Maintenance supplies are used to repair stuff that breaks. This normally happens during the build cycle, with the chance depending on the complexity of the ship and the number of engineering spaces, but weapons have a 1% chance of failing every time they fire,1 and a ship with battle damage can patch itself up with enough MSP. Ammunition, in the form of missiles, obviously gets used up, and it's a good idea to have colliers to support the fleet. And any ship with stays out longer than its rated deployment time suffers from reduced morale, which lowers the accuracy of weapons and increases the time taken to follow orders.

Fuel2 comes from Sorium, a trans-Newtonian mineral that has no other uses. If it's mined from a planet or asteroid, then it can be processed by a fuel refinery. But gas giants also contain Sorium, and while conventional mining from one of those is obviously impossible, a ship fitted with Sorium Harvesters can extract it and turn it directly into fuel. A typical Fuel Harvester should have a batch of Sorium Harvesters, a Refueling System (necessary to transfer the fuel to other ships), and enough fuel capacity to hold a year or two's worth of the fuel. Make sure to check the Tanker and Space Station boxes, too. The tanker box just tells the game that this is a tanker, and can transfer fuel off. You'll want to set the minimum fuel in the Miscellaneous tab, which is how much fuel the system will hold back for the tanker's own use.3 By default it's 10%, which is reasonable for a mobile tanker, but this is a space station, and it should be 0.

Space stations are special in several ways. They're not allowed armor or engines, but to make up for this they can be built by planetary industry, instead of requiring a shipyard, and being subject to the size limits of said yards. Of course, you want to keep them away from enemies, but there are a wide range of functions that stations can perform.

But how does the station get somewhere other than the place it was built, you ask? Simple. Stations are moved about by tugs, which are also useful if you want to move shipyards or even ships that have suffered engine failures. A tug just needs a tractor beam, a reasonable amount of fuel, and as many commercial engines as you like. I typically build mine to be around 10,000 tons, the size of a new commercial shipyard, which is adequate for most tasks. If you're planning on moving a bunch of heavy stuff very far (either building the Aurora equivalent of Ulithi or shipping out lots of orbital habitats) then you might want to go bigger.

Turning back to fuel, there are three potential sources of fuel for a ship: a planet with either a spaceport or a refueling station; a space station with a Refueling Hub (100,000 tons); or a tanker with a Refueling System (500 tons). Fuel transfers at a rate defined by the technology of the Refueling System, or the best refueling system researched for planets and hubs. Hubs and planets can refuel arbitrary numbers of ships in parallel, while a tanker can only refuel one at a time, regardless of how many refueling systems it has. For any transfer of fuel into a fleet, the fleet has to be stationary, and request the fuel from the source.4 If you've researched the Underway Replenishment tech, you can have a tanker refuel other ships in the same fleet at a rate dependent on the tech level. To make this happen, you'll need to open up the ship (not the fleet) in the Naval Operations window and set the Auto-Refuel option from the dropdown. This is great if you're doing a long deployment, and I'd recommend building your standard tanker (engines, refueling system, lots of fuel, ~10,000 tons is usually plenty) to fleet speed unless you're planning on building a specialized fleet replenishment ship.

In terms of shipping, maintenance supplies work fairly similarly to fuel. They're transported by Supply Ships in maintenance storage bays and moved by cargo shuttles between ships5 and by spaceports or cargo shuttle stations from planets, although there's no maintenance hub. I rarely find it necessary to make independent supply ships, as you don't need nearly the volume of maintenance supplies that you do for fuel. In terms of use, they are very different. Commercial ships ignore maintenance entirely, but any military ship that isn't at a maintenance location has a chance of suffering system failure every 5-day build cycle. It also has a clock that ticks up with each cycle, and which is one of the main drivers of the failure rate. While it would theoretically be possible to keep a military ship on station indefinitely by shipping out maintenance supplies, eventually it would become ludicrously expensive, and you'd want to bring it in for an overhaul. An overhaul is performed at a maintenance location, and costs MSP.6 During an overhaul, the ship is unable to do anything and the clock ticks backward at three times the rate time is passing, ending when the clock reaches 0.7

Maintenance can be done either by planetary facilities, which require workers from the planet's population and produce MSP from minerals, or by maintenance modules on space stations, which work in deep space and don't produce MSP. In either case, supporting ships takes MSP, and the tonnage of shipping a facility can support is determined by racial tech and the number of modules available. If there is too much tonnage for the available facilities, maintenance clocks continue to tick, but more slowly than they would normally. The big decision to make on maintenance is exactly how often to overhaul your ships. I tend to do so fairly frequently, usually when they reach their deployment time (discussed below). This is on the grounds that my ships are going to spend the same amount of time in overhaul anyway, so I might as well minimize my failure rate and reduce how long I have to wait if something happens and I need them.

The last use of MSP is repairing battle damage. Ships each have an internal repair rating equal to the number of engineering spaces and any damage control systems they have, and will gradually rebuild themselves if they have enough supplies. If this is too slow, you can put them into a hangar, which will let them use the bigger ship's damage control rating for their repairs. Ships in hangar can also have their armor repaired, which is impossible for internal repairs. Note that hangar space is not subdivided, so you could easily build a 40,000 ton "drydock" space station for your battleships using commercial hangars and damage control systems. Do note that commercial hangars, unlike standard hangars, don't stop the maintenance clocks of whatever is carried in them, although the carried craft can benefit from nearby maintenance modules.

Missiles are very much like fuel in terms of handling. You have Ordnance Transfer Systems for Colliers (which is also the checkbox to use) and while standard magazines are a military system, Commercial Magazines are not. They're much less efficient and explode if they take any damage, but the reduced cost of commercial shipping makes up for it. Note that missiles, unlike fuel and MSP, aren't generic, so you need to make sure your collier has the right kind of missiles for the fleet. Missiles are fairly bulky relative to fuel, so you might have to exceed 10,000 tons for your colliers.

The last clock is deployment time, which is set when you build the ship. When a ship has been out too long, the crew gets restless and less effective. To restore them, ships can either visit a colony with sufficient facilities8 or somewhere with a Recreation Module (100,000 tons). In either case, the deployment clock spins backwards at 10x the rate of time passing. There's nothing consumed during the process, either. The only real problem with this is that there's no order to go somewhere and stay while the clock is rewound, which can be annoying for ships with default orders. The best way around this is to overhaul at the same time, which stops those from triggering. In terms of time, make sure that the maintenance life is longer than the deployment time, as a ship that's over its deployment clock is merely less effective, while one out of MSP is actively in danger.

There are also a few types of ships and stations which don't fall into one of the categories described above, but which can be very useful. When ships are destroyed, they leave wreckage behind, which can be salvaged using ships with salvage modules. These will give you some minerals and a few systems from the destroyed ships. If it's your ship, you can chose to either reuse or scrap the systems, while enemy systems might help you unlock new technology. Check the Stockpile tab of the Economics window. Note that salvage ships need cargo space to put the salvaged materials somewhere in the fleet, either onboard or in an accompanying freighter. The amount salvaged is significantly less than the tonnage of the ship being salvaged, so this isn't usually a huge problem.

Then there are terraforming and mining modules, which can perform functions from orbit that would otherwise require boots on the ground. Mining modules are limited to bodies below a certain radius (set by racial tech) so they're best for cleaning up small asteroid deposits. Terraforming modules are great in cases where you don't want to have to transport workers for them, as they bring their own crews. This is particularly important if the planet is currently extremely hostile, and the infrastructure requirements would be prohibitive. The alternative in those cases are orbital habitats, which house 200,000 people for each 500,000 ton module. Get big tugs if you're going to use those.

Lastly, there are troop transports. These come in three types: regular, drop-capable, and boarding. Generally, use regular types for strategic transports, and make sure your boarding ships are very fast. Drop ships are useful for faster offloads, which may or may not be useful, depending on how you handle surface-to-orbit defenses. The ground warfare system was entirely overhauled in C#, so I'm still figuring it out. However, it should be easy to find information on the Aurora forums. My one recommendation would be to make your ground units a standard size, to make transport easier. For instance, my battalions are always 5,000 tons or a little less. Oh, and bring lots of supplies. Yes, more than that.

I've discussed ship design quite a lot, but one question remains. How do you actually fight? That's a topic I'll cover next time.

1 This usually only matters if you're doing planetary bombardment, or if you try to peck the enemy to death from long range.

2 As a sidenote, fuel stockpile management isn't usually a problem. It's worth keeping an eye on in the Economics window, but if the number is reasonably stable, particularly as a multiple of yearly production on your main planet, your only issue is going to be distribution.

3 It's also worth noting that when a tanker is built, it starts with the minimum fuel instead of a full load. This is great for fuel harvesters, but can make life difficult if you forget to refuel a conventional tanker.

4 This is a major headache in certain situations, because you can't order a tanker to refuel some other ship. For instance, if you have a fleet run out of fuel, you'll need to order a tanker to move to that fleet, then tell the fleet to refuel and go about its business, and then once it's done, tell the tanker what to do. This is a case where the Send Message command (which will interrupt and put something you specify in the event log) is helpful, but it's a pain compared to VB6, where you could tell the tanker to refuel the fleet and what to do afterwards all at the same time.

5 Note that a single shuttle bay moves MSP very slowly. You'll want several on any serious supply ship.

6 For a look at ship maintenance, see this post on the Aurora forums by reader Alsadius.

7 You can also cancel an overhaul, but it takes a month for the ship to return to full strength.

8 The threshold for this is something like 50-100k colonists, so it's not very hard to hit.


  1. June 15, 2020echo said...

    I've been trying to automate tanker transfer between planets and harvesters, but it looks like there's no way except limiting the speed to match the fill time? Hope he adds some extra automation for late game.

    Speaking of logistics, do you have any tips on optimum freighter speed & size? This is a generally interesting question that also came up in the commercial shipping series.
    Faster cargo hauling means a higher RoI, but cost and fuel consumption is non-linear.

  2. June 15, 2020bean said...

    There's more improvements coming down the pipeline. My usual tactic for harvester management is to wait until I get 90% full warnings, then have a tanker do shuttle runs. Check the fleet to see how much fuel it has, and you should have a decent idea of how much fuel your tanker will carry. Be sure to throw in some extra runs to carry the fuel generated while in transit. I usually just repeat orders until I know I'm safe.

    As for freighter size, I once did a spreadsheet on that, but it was for VB6. The big problem is that the results vary with length of run, so I normally just do it more or less by eye. One cargo bay, about 200 HS worth of engines, and same engines, 5 or 6 cry for colony ships. Might dig the spreadsheet out again and see.

  3. June 18, 2020echo said...

    Thanks, and for the whole tutorial series. There's been quite a few parts where I might have given up or put it away for another year if it wasn't for being able to check these posts and the discord.
    Looking forward to the combat post; putting off attacking the illegal ayys camping my system until reading it. It'll be a good end for the series.

    One thing that still bugs me: railguns don't use more power shooting at 90,000kms than at 10,000kms? I guess it's just a copy of the laser wavelength tech.

  4. June 21, 2020Alsadius said...

    FYI, the MSP usage for overhaul is a multiple of the basic usage. A ship sitting in port will use MSP per year equal to 25% of its build cost, so a ship that costs 1000 will use 250 MSP/year. When a ship is in overhaul, this rate is quadrupled, so the same ship would use 1000 MSP/year.

    I wrote a lengthy explanation of maintenance mechanics here: http://aurora2.pentarch.org/index.php?topic=11055.0

  5. June 22, 2020bean said...

    Thanks. I've added a link to that. I was mostly just not interested in mucking around in the guts of that system when I wrote this.

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