Create Aeronautics Server Guide: RAM, Packs and Lag

A Create Aeronautics server runs Minecraft 1.21.1 on NeoForge 21.1.228 or newer, with Create 6.0.10 or newer and the Sable physics library 2.x installed next to the Aeronautics jar. Every player needs the same mods, and Create has to be exactly the server's version. Create with a few addons, Aeronautics among them, fits on 4GB of RAM, while a big Create pack such as All of Create Aeronautics starts at 6GB and runs best on 8GB.

We checked everything below on 25 October 2026 against Modrinth, CurseForge and the files inside the mods and server packs: the versions that have to match, mod versus modpack, how much memory, the install, and the config lines that decide what your airships cost the server.

The versions that have to match

Create Aeronautics exists for one Minecraft version and one loader. Its pages on Modrinth and CurseForge list Minecraft 1.21.1 on NeoForge only: no Fabric build and nothing for 1.20.1 or older. A server that runs Create on Fabric, or on 1.20.1, cannot add it without moving to NeoForge 1.21.1 first.

The requirements come from the neoforge.mods.toml files inside the 1.3.2 jar. Each part of it asks for NeoForge [21.1.228,), Create [6.0.10,) and Sable [2.0.0,3.0.0), and every one of those dependencies is marked side = "BOTH": the server and every player need them. A Sable 3.x release would fall outside that range, so update Sable only to versions that Aeronautics accepts.

That one jar, create-aeronautics-bundled-1.21.1-1.3.2.jar, holds three mods. The project page describes them as Simulated (assembly, redstone components and the tools for handling moving structures), Aeronautics (hot air, propellers and floating rocks) and Offroad (wheels and land vehicles). The page also lists one known incompatibility: visual issues with Iris shaders. That is a problem in the players' game rather than on the server, so tell your players before they install a shader pack.

Mod on its own or a modpack

There are four common ways to run it, and they differ a lot in size.

Create, Aeronautics and your own addons. Three jars plus the addons you pick. You decide when anything updates, and the mod list stays small. This is the light option.

All of Create Aeronautics. The pack built around it. Version 2.8 came out on 13 October 2026 for NeoForge 21.1.256, and its server pack holds 195 mod jars: Create 6.0.10, Aeronautics 1.3.2 and Sable 2.0.6, plus Lithium, ModernFix, FerriteCore and Clumps. Its server files set a 4GB Java heap (JAVA_ARGS="-Xmx4G -Xms4G" in variables.txt). The same author's All of Create (2.6, also 13 October) is the version without Aeronautics.

Create Ultimate Selection 2. Version 12.9.0 from 23 October 2026 puts 332 mod jars on the server, spark included, with the same 4GB heap in its server pack. It ships Aeronautics 1.2.1 and Sable 2.0.0 rather than the newest versions, so players install the pack as it is and do not update single mods inside it. It also moves quickly: six releases between 3 and 23 October.

All the Mods 10 Aeronautics. ATM10 with Aeronautics added: version 0.7.1 from 30 September 2026, with 418 mods in its server files, which set no heap at all. Size it like ATM10, from 12GB. Our ATM10 server requirements guide explains why that pack needs more.

How much RAM: 4GB, 6GB or 8GB

Neither Create, Aeronautics nor the packs publish player counts, so size the server by what you install. These are the sizes on our Create hosting page, with the monthly prices for the Netherlands, Germany and Poland, VAT included:

The reasoning for the packs: their server files give Java a 4GB heap, and Java needs memory on top of the heap for itself. That is why a pack starts at 6GB. On 8GB you can raise the heap to 6GB once contraptions, vehicles and players add up and still leave room for the rest. Set the heap with the JVM arguments in the Startup tab of the panel, or in user_jvm_args.txt if your server starts through NeoForge's own run script. The packs' start scripts rewrite that file from JAVA_ARGS in variables.txt on every start, so with those scripts you change the heap in variables.txt. More players and bigger builds always need more, and because the server simulates every moving structure, a busy Create world loads the CPU as well as the memory.

Installing Aeronautics on a NeoForge server

For the mod on its own:

1. Install NeoForge for Minecraft 1.21.1, version 21.1.228 or newer.
2. Pick Java 21.
3. Upload create-1.21.1-6.0.10.jar, sable-neoforge-1.21.1-2.0.6.jar and create-aeronautics-bundled-1.21.1-1.3.2.jar to the mods folder, plus any addons that list NeoForge 1.21.1.
4. Start the server once, accept the EULA in eula.txt and start it again.
5. Send your players the exact list of jars. A player with a different Create version cannot join, because Create puts its own version number on its network channel and NeoForge refuses the connection when it does not match.

For a modpack, download the server pack from the pack's files on CurseForge. The All of Create Aeronautics server pack contains config, datapacks, defaultconfigs, mods and schematics folders, a server.properties and the ServerPackCreator start scripts (start.sh and start.bat) with their settings file, variables.txt. Those scripts install NeoForge themselves and write JAVA_ARGS into user_jvm_args.txt. On a panel that installs NeoForge for you, upload the folders and leave the scripts out. Players install the same pack version through the CurseForge app.

On NeoForge 1.21.1, server configs such as create-server.toml live in the config folder, and a copy in world/serverconfig overrides them for that world. If a change does nothing, check whether the world has its own copy.

Where the lag comes from

Aeronautics vehicles are what Sable calls sub-levels: separate block structures whose physics the server simulates every tick, on top of Create's own contraptions and trains. That work lands on the server's CPU, and it grows with the number and size of the vehicles in loaded areas. These are the settings that control it, with the defaults we read from the configs in the All of Create Aeronautics 2.8 server pack.

Cap vehicle size in simulated-server.toml

config/simulated-server.toml has its own maxBlocksMoved under [assembly], with the comment "Maximum amount of blocks in a structure assemble-able by Physics Assemblers, Swivel Bearings, or other means". The default is 128000. It is a different setting from Create's maxBlocksMoved in config/create-server.toml, which is 2048 by default and covers pistons, bearings and Create's other movers. Lowering the Create one does nothing for airships.

There is no right number for every server. On a public server, start well below 128000, tell your builders the cap, and raise it when someone hits it with a build you are happy to simulate.

Leave the physics substeps at 2

sub_level_substeps_per_tick in config/sable-server.toml defaults to 2, with a range of 1 to 10. Sable's own comment: "Higher values will be significantly more performance intensive, but will have higher accuracy." Leave it at 2 unless vehicles visibly misbehave, and measure before and after if you change it.

The same file has sub_level_storage_pruning = false, which Sable describes as "Prunes and deletes empty sub-level storage files. Experimental." Leave it off unless you have a fresh backup of the world.

Trains and Create contraptions

Create's own limits sit in config/create-server.toml: maxBlocksMoved (2048), maxBogeyCount (20 bogeys per train) and maxAssemblyLength (128 blocks of station track). Create also ticks every train once per server tick, wherever it is, including trains on lines where nobody is around, so a big scheduled network costs server time even when the server is empty. Our Create server guide has more on contraptions, trains and item lag.

Vehicle movement over UDP

Sable sends vehicle movement to players over a UDP channel that it opens on the server's own address and port (attempt_udp_networking = true in config/sable-common.toml). When a player joins, Sable sends them a token over the normal connection, and their game sends it back over UDP. In Sable 2.0.6 the server then pings each player over UDP every 2.5 seconds. When a player stops answering for about 25 seconds, Sable logs "failed to respond to any keep-alive packets after ~25000ms, kicking them to TCP" and that player carries on over the normal connection.

That gives you a quick check in the console. "UDP authentication complete" for a player means their UDP packets reach the server's port. If that line never shows up for anyone, UDP is not getting through to the port, and players stay on the normal connection. The "kicking them to TCP" warning means something else: the player did connect over UDP, then stopped answering the pings. Setting disable_udp_pipeline = true turns the UDP channel off completely. Sable's comment says that helps with "certain mods like Replay mod and certain networking setups", at the cost of "worse performance and latency for networking sub-levels".

Measure before you guess

spark shows which mods and which parts of their code take the most tick time, and it only has to be installed on the server. Create Ultimate Selection 2 ships it; All of Create Aeronautics does not, so add it yourself. Our spark profiler guide covers reading a profile. Profile during a busy evening, not on an empty server.

Before every update

All of Create Aeronautics has had 19 releases on CurseForge since 19 April 2026, and Create Ultimate Selection 2 had six between 3 and 23 October. Neither server pack includes a backup mod. Make a backup in the panel before each update, read the changelog, update the server and every player together, and keep the old backup until the world has run a few days on the new version. Our guide to restoring a world from a Pterodactyl backup shows the rollback if an update goes wrong.

If you want a server that is ready for this, our Create mod server hosting page has the same sizing as above with a plan picker for all nine regions. In the Netherlands, Germany and Poland, Standard runs on a Ryzen 9 3900X-class CPU with DDR4 and Premium on a Ryzen 9 9950X with DDR5. The CPU is shared on every plan, and NVMe storage and DDoS protection are included.

FAQ

Does Create Aeronautics work on Fabric? No. On 25 October 2026 Modrinth and CurseForge list Create Aeronautics for NeoForge on Minecraft 1.21.1 only. Sable, the physics library it runs on, has Fabric builds, but Aeronautics itself does not.

How much RAM does a Create Aeronautics server need? Create with a few addons, Aeronautics among them, fits 4GB. A big pack such as All of Create Aeronautics sets a 4GB heap in its server files, so it starts at 6GB and runs best on 8GB. Big worlds and public servers need 12GB or more.

Do players need Create Aeronautics installed to join? Yes. Create, Sable and Aeronautics are all required on both sides, and Create has to be exactly the server's version. Give players the same jars as the server, or with a modpack, the same pack version.

Which Minecraft version does Create Aeronautics use? Minecraft 1.21.1 with NeoForge 21.1.228 or newer and Java 21. The newest version on 25 October 2026 is 1.3.2 from 29 August 2026.

Why do airships lag my server? Every vehicle is a physics structure the server simulates each tick. Cap their size with maxBlocksMoved in config/simulated-server.toml (128000 by default), keep Sable's sub_level_substeps_per_tick at 2, and use spark to see what is actually taking the tick time.