Rocket Heat and Exhaust From Launch - Testing (Spaced Out)

[Jay H.]

On heat generated by rockets, the wiki https://oxygennotincluded.fandom.com/wiki/Rocketry_(Spaced_Out) currently says: "Any gases within these tiles will be superheated, including any gases emitted by the engines themselves; the exact amount of heat is unclear."

I was thinking of making a rocket powered petroleum boiler, but didn't know if rockets would generate enough heat. The wiki does not provide enough information for the current version of rockets so I did some testing. Here are some observations from testing

TESTING METHODS: In sandbox mode a rocket platform was built over a layer of bunker tiles to isolate exhaust/conduction heating effects from magical penetrating rocket plume heating. Only carbon dioxide engine and steam engine have been tested so far.

(1) Like previous versions heat is generated both in the 9x3 rectangle "plume" and from conduction from the exhaust.

(2) Testing a carbon dioxide engine and a steam engine, the magical 9x3 rectangular heating effects appeared to be identical for both engines. About 40C degrees of heating. The distribution of heat is not uniform over the 9x3 rectangle with tiles closer to the rocket platform experiencing more heating.

(3) Bunker tiles, despite not being a gas, do experience the 40C heating of the plume. Liquid water tiles are unaffected by the 9x3 heating rectangle. Gaseous steam is affected by the 9x3 heat cone of about 40C. Note, the specific heat of steam is about 10x that of steel. Thus heating steam creates 10x more heat than from bunker tiles alone. However, the water must be heated into steam before it experiences the rocket plume heating.

(4) Heat from the exhaust gas greatly exceeds heating from the 9x3 rocket plume alone. Exhaust gas heat from the steam engine is much higher than from the carbon dioxide engine, as expected because carbon dioxide has both a low specific heat and low conduction. Quantifying the amount of heat from the exhaust gas portion is difficult as it probably depends largely on how the heat from the exhaust gas is captured.

Because using rocket heat requires likely complicated setups to capture the exhaust heat and cannot rely upon the rocket plume alone, using rocket heat to power any kind of boiler seems less reliable than using a smelter with petroleum coolant, or magma if it is available.

[Fradow]

41 minutes ago, Jay H. said:

On heat generated by rockets, the wiki https://oxygennotincluded.fandom.com/wiki/Rocketry_(Spaced_Out) currently says: "Any gases within these tiles will be superheated, including any gases emitted by the engines themselves; the exact amount of heat is unclear."

Someone's gotta read the code! Though I didn't manage to get precise DTU figures from the code for vanilla, so I assume it will be equally difficult for SO.

41 minutes ago, Jay H. said:

(1) Like previous versions heat is generated both in the 9x3 rectangle "plume" and from conduction from the exhaust.

You might want to separate gas exhaust and dry exhaust as much as possible. If it didn't change from vanilla (I'm pretty sure it didn't), gas exhaust is at a fixed temperature, while dry exhaust heats up any non-vacuum cell at a fixed rate (which means it also heats up the gas exhaust).

41 minutes ago, Jay H. said:

(2) Testing a carbon dioxide engine and a steam engine, the magical 9x3 rectangular heating effects appeared to be identical for both engines. About 40C degrees of heating. The distribution of heat is not uniform over the 9x3 rectangle with tiles closer to the rocket platform experiencing more heating.

40°C of what material? Oops, you said Bunker tiles below, so it's Steel. It's still easier to communicate with DTUs. When you talk about heat, you want to talk about DTUs, which are agnostic of the building material. 40°C of Sedimentary Rock and Igneous Rock (for example), isn't quite the same amount of heat.

Tiles closer to the rocket platform are heated up by the dry exhaust for longer because they are heated up while the rocket rises. I'm pretty sure that the heating function is done every game tick in the 9x3 area under the current rocket position.

Basically, rockets accelerate until they reach their top speed, and after that have a constant speed. I've not calculated the acceleration. I did test the top speed at one point for vanilla Steam rockets, and I'm pretty sure it's the same for all rockets. More search should uncover that number, though it's trivial to re-test it.

41 minutes ago, Jay H. said:

(3) Bunker tiles, despite not being a gas, do experience the 40C heating of the plume. Liquid water tiles are unaffected by the 9x3 heating rectangle. Gaseous steam is affected by the 9x3 heat cone of about 40C. Note, the specific heat of steam is about 10x that of steel. Thus heating steam creates 10x more heat than from bunker tiles alone. However, the water must be heated into steam before it experiences the rocket plume heating.

Liquids are not affected? That's very interesting. That challenges my understanding of the dry exhaust, and opens up new venues to negate it.

41 minutes ago, Jay H. said:

(4) Heat from the exhaust gas greatly exceeds heating from the 9x3 rocket plume alone. Exhaust gas heat from the steam engine is much higher than from the carbon dioxide engine, as expected because carbon dioxide has both a low specific heat and low conduction. Quantifying the amount of heat from the exhaust gas portion is difficult as it probably depends largely on how the heat from the exhaust gas is captured.

Hum, I'm not sure that precise, but more to the point, it's meaningless if the gas exhaust isn't hot enough for your purpose. In the case of Petroleum Boiler, you need at least 405°C or so. What's the temperature from the Steam Engine in SO? It is 150°C in vanilla, not quite hot enough to refine Petroleum.

To quantify the amount of heat, what you can do is a tall perfectly insulated vacuum rocket chimney from which you launch the rocket. Check how much Steam there is and how hot it is after a launch to get the approximate amount of heat per cell for the top speed phase. It's a bit trickier for the acceleration phase, but I guess you could count all the Steam mass and temperature around the launch.

41 minutes ago, Jay H. said:

Because using rocket heat requires likely complicated setups to capture the exhaust heat and cannot rely upon the rocket plume alone, using rocket heat to power any kind of boiler seems less reliable than using a smelter with petroleum coolant, or magma if it is available.

It depends on what you call "complicated". It isn't as much as complicated as bulky (much like a research reactor). I'm pretty sure you can rely on the dry exhaust alone when using a powerful enough engine (hydrogen), though the main issue is how to automate the rocket in SO, something I've not delved in yet.

The best late-game way to power a petroleum boiler likely remains a Thermium aquatuner (or several) though: it doesn't require an influx of materials (like a metal refinery), an unsustainable magma source (the core), a volcano, or any kind of exploit (like a tricked tepidizer).

It's still interesting to mess around with rockets, just because.

[Jann5s]

I tend to put à big slab of métal below my rockets with some petroleum flowing through it in pipes to heat a steam chamber. It doesn’t recoup all the heat, but it’s simple and it captures a lot. A film of liquid on top allows to keep the loaders cool too.