Fuel compression and Stacking?

[Arugela]

How much could you realistically compress fuel and gasses. And what amount of stacking fuel tanks could this equal too If you have no money concerns and used the greatest amount of knowledge available. And what would that cost compared to the cost of stacking fuel tanks in the game currently?

And by stacking I mean putting multiple fuel tanks in the exact same spot by placing them on the end of one another and moving one up to the same physical location so they look like one item. Edited November 23, 2015 by Arugela

[Kyrt Malthorn]

Fuel in the game is said to be liquid - it's density and usage in most engines seems to correspond to RP1, which is basically kerosene. It's very hard to compress liquid - especially in space, where the difference in pressure would be huge. However, liquid fuel and oxidizer also seem similar to liquid hydrogen and liquid oxygen. (Especially since hydrogen makes the ideal propellant for a real life nuclear engine, and the NERV in KSP uses the same liquid fuel.) These are both gases at room temperature. The way you compress them is by refrigeration - the gas condenses into a liquid. These are called cryogenic fuel. ...since in KSP they are called liquid fuel, if they are meant to correspond to hydrogen and oxygen, they're already cryogenic and as dense as they're going to get. Realistically these fuel tanks should actually be drawing power for active refrigeration. They don't.

I generally think of the LF/O in KSP as a microcosm rather than any one kind in RL. I would also say fuel stacking just isn't realistic. If you want more fuel realism, check out the RealFuels mod and the Stockalike Realfuels Configs, which make stock engines use real world fuels without changing their performance.

[jf0]

In real life most rocket propellants are liquids (or solids) which don't compress much, even under very high pressure. The reason liquid propellants are good is because they are dense without storing under pressure. High pressure means you need stronger and heavier tanks. This is why liquid oxygen,for example, is used in rockets rather than compressed oxygen gas.

The density of some liquid propellants can be increased a tiny bit by (furthur) cooling and pressurising, but nowhere near doubling the density (which is what you get by clipping two tanks into each other)

[More Boosters]

[quote name='Kyrt Malthorn']hydrogen and oxygen, they're already cryogenic and as dense as they're going to get.[/QUOTE]

Not necessarily true. Further refrigeration can make hydrogen slightly more viscous and therefore a bit denser.

[KrazyKrl]

Well, [URL="https://en.wikipedia.org/wiki/Slush_hydrogen"]Slush Hydrogen is already being proposed as rocket fuel[/URL], with density increases of up to 20%.

And [URL="http://www.grc.nasa.gov/WWW/Fuels-And-Space-Propellants/GELLED.htm"]NASA has already done work on [I]Gelled[/I] hydrogen.[/URL] "The propellant density increases and their attendant Isp changes with the aluminum additives allow a payload increase of 14 to 35 percent by replacing the Space Shuttle Solid Rocket Booster with a Liquid Rocket Booster using O2 /RP-1 /Al and NTO /MMH /Al, respectively." [URL="http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19910014991.pdf"]Here's a PDF of some data.[/URL]

If you [I]really[/I] wanted to get down to it. You could make [URL="https://en.wikipedia.org/wiki/Metallic_hydrogen"]Metallic Hydrogen[/URL] at 250,000 atmospheres of pressure. But good luck fueling a rocket with [URL="https://en.wikipedia.org/wiki/Degenerate_matter"]degenerate matter[/URL]. Edited November 23, 2015 by KrazyKrl

[Arugela]

Oh, well! I'm making sci fi replicas anyway. So, I guess I can pretend. 8)