Methalox mass ratio should be 1:3.6, not 1:4

[HephaistosFnord]

Besides being realistic, this also means that the volume ratio of a pure methane tank to a pure oxygen tank is 1:2. Since tanks already come in doubling sizes, this means that you can combine pure lox tanks and pure lch4 tanks without having to do any real math.

[The Aziz]

Exactly, 1:4 makes it easier to calculate.

If I need to produce 4 tons of methane I know I need also 16 tons of oxygen. Not some weird number I have to calculate.

Also

 

 

[pandaman]

I don't see this as a problem.  Yeah, it may not be 100% realistic, but it's not that far off and certainly close enough for game purposes.

I'm sure there are many other areas where  these kinds of things are 'rounded for convenience' .  

[HephaistosFnord]

Again, 3.58:1 is actually easier than 4:1, bc 4:1 is a weird volume ratio, while 3.58:1 mass ratio is a straight 2:1 volume ratio, which matches the volume increase between fuel tank sizes.

[Lyneira]

The proposal's purpose would be that changing the ratio would allow 1 pure CH4 tank plus 1 pure oxidizer tank to make the perfect ratio for a methalox engine. But since we have no pure oxidizer tanks, there doesn't seem much benefit to that.

[HephaistosFnord]

True, we really need a tank switcher that lets any methalox tank be configured to either pure lox, pure ch4, or shared bulkhead methalox.

[Lyneira]

What's the use case for a pure oxidizer tank?

[pandaman]

2 hours ago, Lyneira said:

What's the use case for a pure oxidizer tank?

When craft use a mixture of Rocket and Jet engines (or Rapiers).

[The Aziz]

Well... You're more likely to use more methalox than oxidizer then. Jet engine doesn't use oxidizer, and once you're in closed cycle, it drains both resources evenly. I've been there, flying a spaceplane, running out of LF(methane now) faster than OX.

[Lyneira]

29 minutes ago, pandaman said:

When craft use a mixture of Rocket and Jet engines (or Rapiers).

A combination of methane tanks (enough for the flying portion) and methalox tanks covers this situation perfectly though. To make a use case for a pure oxidizer tank, it would have to be consumed by something else than a methalox engine.

[Donkey32]

I imagine MANY places, using ISRU in Kolonies, where a pure OX tank could be useful (besides propulsion).
Kind of depends how far down the rabbit hole of habitat maintenance one wants to go. Will the need for snacks and a breathable environment be built into the stock game?

[pandaman]

On 3/22/2023 at 12:20 PM, Lyneira said:

A combination of methane tanks (enough for the flying portion) and methalox tanks covers this situation perfectly though. To make a use case for a pure oxidizer tank, it would have to be consumed by something else than a methalox engine.

True...

But also you could discard the pure Ox tanks before reentry to save mass, reduce drag and assist with balance etc.

[Lyneira]

3 minutes ago, pandaman said:

True...

But also you could discard the pure Ox tanks before reentry to save mass, reduce drag and assist with balance etc.

Well, you can do that with methalox tanks too if you transfer the methane from them into the dedicated methane tank and then drop the tanks. Although that would make your craft not-reusable, which is usually the reason for choosing a rapier or jet/rocket hybrid in the first place!

[pandaman]

2 hours ago, Lyneira said:

Well, you can do that with methalox tanks too if you transfer the methane from them into the dedicated methane tank and then drop the tanks. Although that would make your craft not-reusable, which is usually the reason for choosing a rapier or jet/rocket hybrid in the first place!

Yes of course, I'm not disagreeing with any of your points. 

Like so many parts in the game though, having dedicated Ox tanks just gives different mission profile options.  I can't say I would be likely to use them much myself, but that's not to say others wouldn't find them very useful.