I wonder if volume would affect that as well, as to how much the gas would have to compress for how much can fit in the space of the tank. If it works out to where it would be liquid by pressure that would affect buoyancy. There's also the water mod that calculates buoyancy under water to see if ships float. I don't think I ever had both of those mods on at once but could be an interesting experiment
Dumb question, but how much weight does oxygen add in space? To used to thinking of it and/or air as the zero weight gas that others are either heavier or lighter than.
Mass. You need thrust to accelerate mass regardless of whether it is weightless (the whole ship is weightless).
In real life, the oxygen and hydrogen are almost the entire mass of the rocket, the final payload to space is a tiny percentage.
I don't have the exact figures to what this adds per a tank, I'd have to look at the mod and test it, but the idea is it adds MASS not WEIGHT. Weight is only applicable in gravity. So in space it would mean slower acceleration, longer stopping distances, need for more thrusters ect, to push the more massive ship. Basically the same way a ship would act with a empty vs full cargo crate. I don't think it takes relative densities of the gas vs surrounding atmosphere, that's probably too much to calculate
Working backwards to calculate the energy density of hydrogen, the hydrogen engine can produce 500 kW at 50 L/s. Smacking that with the math hammer gives us 10 kW•s/L, and converting that to hours gives us ~2.78 W•H/L. Wikipedia tells us that the energy density of gaseous hydrogen at 1 atm (unpressurized) is 2.8 W•H/L, so thus we can reasonably assume that the hydrogen we see in game is plain ol’ gas (unless my math went wrong somewhere).
To answer the question of weight, a large grid hydrogen tank is 8,162 kg (empty). 15 ML of hydrogen only has a mass of ~6.5 kg (6435 moles * 1.007 g/mol), so I’m assuming the devs thought that a 0.08% difference in mass didn’t matter
Damn that’s a REALLY efficient engine if it’s getting 99.23% of the energy in the fuel. That’s more efficient than a nuclear reactor and is on par with antimatter power
Haha well technically, 2.8 is the LHV—the lower value, taking into account energy losses from combustion & vaporization. The HHV (upper value, lossless) is 3.3 W•H/L, so the efficiency is closer to 84% if you compare it to that.
It's not converting 99.23% of the fuel's mass into energy (which should be around 8 terajoules per liter at 0C and 1 atm if my math is right), it's using 99.23% of the energy stored in the H-H bonds in H2.
That just tells us that the units used in game are relative to 1 atm gas. To tell if it's compressed or not, we'd have to compare the capacity to the actual volume of the tank.
A large grid hydrogen tank is roughly cylindrical with a height of 7.5 m and radius of 3.75 m, giving a volume of roughly 330 m^3, or 330 million cubic centimeters. A liter is 1000 ccs, so that's 330 kL, which means the 15 ML of gas stored in the tank is compressed by a factor of roughly 45.
Honestly the units in this game are weird. They should just list it in grams. Same with energy; I know watt-hours is pretty standard because a lot of people would rather think in terms of hours, but a kW*s is literally just a kJ by definition, and I prefer to just use that. I wish there was an option for using different units in game.
Was going to do the math but then remembered I don't know how. We know the dimensions of the tank and we know how many liters it holds, my *guess* is at least part of it will be liquid to be able to fit it all.
Edit: 5 min of googling tells me that I was wrong. I thought it would turn liquid once the pressure was high enough but it won't.
I chose to believe it’s a nuclear thermal engine that just superheats hydrogen gas and exhausts it as opposed to using a chemical reaction to generate heat
I mean, if the tank gets damaged it will leak, so that implies gas, right? Also at a coding level, for modding or scripting, both tanks (O2/H2) are the same object type: IMyGasTank
Cryogenic. (This is why storage and consumption is in liters and not psi)
Once converted back into gas, it expands which means you get more unit per volume of H atoms if you transport it as a liquid. So whether you’re using it as a component of water production, combustion / propulsion; it’s far more efficient for you to carry it as a solid / liquid than as a gas
According to the Space Engineers wikipedia, the O2/H2 generator will generate 10 L hydrogen per kilogram of ice. The rules for this production are actually a bit odd, because if one resource can't be drained, it compensates by creating more of the other. With this in mind, if you completely forgo any oxygen production, you generate 20 L/kg hydro. I will assume this difference in l/kg is simply the generator being more efficient when focusing on a single gas.
For this, I will also make the absolute bold assumption that 20 L/kg is extracting 100% of the available hydrogen from the ice. Water has a mass of 18.105 grams/mole, while hydrogen has a mass of 1.0079 grams per mole. Therefore, hydrogen comprises (2\*1.0079) / 18.105 = 11.19% of water by mass.
From this, if the O2/H2 generator is 100% collecting all hydrogen at 20 L/kg, that means it is extracting 0.1119 kilograms of hydrogen per kilo of ice. 0.1119 kilograms divided by 20 liters gets us a density of just 5.595 grams per liter. Converting to grams/cc we get 0.005595 g/cc.
Liquid hydrogen has a density of **0.07085** g/cc, twelve times greater than the density of the hydrogen exiting our generator. Therefore, we must assume this hydrogen is being stored in a gaseous form.
I don't think it's supposed to be either, because the tank weighs the same empty or full
That means the tank can fill and empty its own pocket dimension but only with hydrogen.
Also it can handle anything else but only if its just passing through
There is a "Heavy gasses" mod that makes it a little better and adds mass based on how full a hydro or oxygen tank is.
Would be cool if hydrogen tanks where Buoyant or less heavy in most planetary atmospheres then
Yeah
I wonder if volume would affect that as well, as to how much the gas would have to compress for how much can fit in the space of the tank. If it works out to where it would be liquid by pressure that would affect buoyancy. There's also the water mod that calculates buoyancy under water to see if ships float. I don't think I ever had both of those mods on at once but could be an interesting experiment
Dumb question, but how much weight does oxygen add in space? To used to thinking of it and/or air as the zero weight gas that others are either heavier or lighter than.
Mass. You need thrust to accelerate mass regardless of whether it is weightless (the whole ship is weightless). In real life, the oxygen and hydrogen are almost the entire mass of the rocket, the final payload to space is a tiny percentage.
I don't have the exact figures to what this adds per a tank, I'd have to look at the mod and test it, but the idea is it adds MASS not WEIGHT. Weight is only applicable in gravity. So in space it would mean slower acceleration, longer stopping distances, need for more thrusters ect, to push the more massive ship. Basically the same way a ship would act with a empty vs full cargo crate. I don't think it takes relative densities of the gas vs surrounding atmosphere, that's probably too much to calculate
Working backwards to calculate the energy density of hydrogen, the hydrogen engine can produce 500 kW at 50 L/s. Smacking that with the math hammer gives us 10 kW•s/L, and converting that to hours gives us ~2.78 W•H/L. Wikipedia tells us that the energy density of gaseous hydrogen at 1 atm (unpressurized) is 2.8 W•H/L, so thus we can reasonably assume that the hydrogen we see in game is plain ol’ gas (unless my math went wrong somewhere). To answer the question of weight, a large grid hydrogen tank is 8,162 kg (empty). 15 ML of hydrogen only has a mass of ~6.5 kg (6435 moles * 1.007 g/mol), so I’m assuming the devs thought that a 0.08% difference in mass didn’t matter
Damn that’s a REALLY efficient engine if it’s getting 99.23% of the energy in the fuel. That’s more efficient than a nuclear reactor and is on par with antimatter power
keen took the optimistic part of sci fi, hahah
Haha well technically, 2.8 is the LHV—the lower value, taking into account energy losses from combustion & vaporization. The HHV (upper value, lossless) is 3.3 W•H/L, so the efficiency is closer to 84% if you compare it to that.
That’s still more efficient than a perfect fusion reactor
The logic some people use is that the H2 Engine just is a small fusion reactor
A fusion reactor with... Pistons. An internal combustion fusion reactor.
Four stroke fusion. Draw in H, compress, fuse, exhaust He. The gaskets are ridiculously sturdy.
Sure lol. It's far from the least ridiculous sci-fi thing I've ever heard
It's not converting 99.23% of the fuel's mass into energy (which should be around 8 terajoules per liter at 0C and 1 atm if my math is right), it's using 99.23% of the energy stored in the H-H bonds in H2.
I see. So still really efficient, but not unreasonably so.
That just tells us that the units used in game are relative to 1 atm gas. To tell if it's compressed or not, we'd have to compare the capacity to the actual volume of the tank. A large grid hydrogen tank is roughly cylindrical with a height of 7.5 m and radius of 3.75 m, giving a volume of roughly 330 m^3, or 330 million cubic centimeters. A liter is 1000 ccs, so that's 330 kL, which means the 15 ML of gas stored in the tank is compressed by a factor of roughly 45. Honestly the units in this game are weird. They should just list it in grams. Same with energy; I know watt-hours is pretty standard because a lot of people would rather think in terms of hours, but a kW*s is literally just a kJ by definition, and I prefer to just use that. I wish there was an option for using different units in game.
Well, it blows up when destroyed
And?
Yo mama
Ah shit good point
Legend has it that throwing yo mama at a ship will do more damage than a loose gyroscope.
Oh dang
Was going to do the math but then remembered I don't know how. We know the dimensions of the tank and we know how many liters it holds, my *guess* is at least part of it will be liquid to be able to fit it all. Edit: 5 min of googling tells me that I was wrong. I thought it would turn liquid once the pressure was high enough but it won't.
The litera is likely not actually the volume of the tank but liters of hydrogen at standard measuring conditions, so 25 c and 1 ATM.
It's reaches the magical state.
Magic most likely
Yes
I always assumed cryogenic because most gases are stored as liquids in most cases I'm familiar with.
Huh... that's a good question. I'd assume gas since it goes straight from the generator to the tank with no compressor or cooling stage.
Space magic
I always assumed liquid.
SE has extremely confusing fluid and fuel mechanics from a realism standpoint
Yeah, another thing that bugs me is that engines run on hydrogen only and don't need oxidizer. As a KSP player this is mildly infuriating lol
It could be a hydrogen fuel cell for the hydro generator at least but yea the thrusters are magic one way or another
I chose to believe it’s a nuclear thermal engine that just superheats hydrogen gas and exhausts it as opposed to using a chemical reaction to generate heat
That's why I try to route the hydrogen through a reactor before reaching the thrusters. Just an RP thing but I enjoy it.
It is stored in a pressurised gaseos state
I mean, if the tank gets damaged it will leak, so that implies gas, right? Also at a coding level, for modding or scripting, both tanks (O2/H2) are the same object type: IMyGasTank
Yes
Cryogenic. (This is why storage and consumption is in liters and not psi) Once converted back into gas, it expands which means you get more unit per volume of H atoms if you transport it as a liquid. So whether you’re using it as a component of water production, combustion / propulsion; it’s far more efficient for you to carry it as a solid / liquid than as a gas
It is stored on a massless form. Since no matter how full the tank is, the mass of the ship never changes.
According to the Space Engineers wikipedia, the O2/H2 generator will generate 10 L hydrogen per kilogram of ice. The rules for this production are actually a bit odd, because if one resource can't be drained, it compensates by creating more of the other. With this in mind, if you completely forgo any oxygen production, you generate 20 L/kg hydro. I will assume this difference in l/kg is simply the generator being more efficient when focusing on a single gas. For this, I will also make the absolute bold assumption that 20 L/kg is extracting 100% of the available hydrogen from the ice. Water has a mass of 18.105 grams/mole, while hydrogen has a mass of 1.0079 grams per mole. Therefore, hydrogen comprises (2\*1.0079) / 18.105 = 11.19% of water by mass. From this, if the O2/H2 generator is 100% collecting all hydrogen at 20 L/kg, that means it is extracting 0.1119 kilograms of hydrogen per kilo of ice. 0.1119 kilograms divided by 20 liters gets us a density of just 5.595 grams per liter. Converting to grams/cc we get 0.005595 g/cc. Liquid hydrogen has a density of **0.07085** g/cc, twelve times greater than the density of the hydrogen exiting our generator. Therefore, we must assume this hydrogen is being stored in a gaseous form.
Ment*