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40 votes

Why can't cryogenic oxygen and cryogenic kerosene be "stored" together?

As Organic Marble hints, there is about 140 degrees Celsius between kerosene's freezing point and oxygen's boiling point; there's no temperature at which both are liquid. Even if the propellants were ...
Russell Borogove's user avatar
36 votes
Accepted

Why would sub-cooled LOX tanks need to "topped-off" until the last minute or so?

At a pressure of 1 bar, the temperature of liquid boiling oxygen stabilizes at 90 K. For sub-cooling of LOX, the temperature should be lower. It is possible to cool LOX by forced evaporation by a ...
Uwe's user avatar
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32 votes
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What is "anti-geysering" and why would you turn it off 70 seconds before launch?

Partial answer to What is "anti-geysering"... tl;dr Anti-geysering systems are intended to stop geysering, which is a phenomenon that can occur in long vertical pipes of cryogenic fluid ...
Organic Marble's user avatar
22 votes

Why can't cryogenic oxygen and cryogenic kerosene be "stored" together?

Because it will almost certainly go KABOOM. Intimately mixed fuels and oxidizers are pretty much indistinguishable from explosives, and in particular, LOX intimately mixed with flammable hydrocarbons ...
ikrase's user avatar
  • 8,874
21 votes
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How do rockets keep their fuel in a liquid state?

As small amounts of LOX boil off heat is removed from the remaining volume. Boiloff actively cools the fluid and helps keep the remainder liquid. Rockets typically have vents to aid in managing the ...
Saiboogu's user avatar
  • 6,417
21 votes

Why a 900,000 gallons LOX storage tank at Launch Complex 39?

Excess capacity was needed in the storage sphere to allow for multiple attempts in a launch campaign. Much of the propellant was recovered during a scrub but not all. The storage spheres were loaded ...
Organic Marble's user avatar
18 votes

Falcon-9's subcooled LOX is continuously refrigerated in-situ, what about its subcooled RP-1?

RP-1 isn't cryogenic actually. The subcooling for RP-1 is only to cool it to slightly below the freezing point of water, 20 F. At that temperature, no extreme cooling is required. The temperature ...
PearsonArtPhoto's user avatar
  • 121k
16 votes

Is there any satellite that uses LOX as oxidizer?

In short: no. LOX, or any cryogenic fuel will slowly warm up without active cooling, resulting in boil off. Since satellites normally want long duration station keeping, this is non-ideal. As such, ...
fyrepenguin's user avatar
  • 1,670
15 votes

Why isn't LOX/UDMH used in staged combustion rockets now-a-days?

N2O4/UDMH is the choice if you need a non cryogenic storable hypergolic fuel. But UDMH is toxic and carcinogenic and should be avoided if possible. UDMH is also corrosive. LOX/UDMH is not storable (...
Uwe's user avatar
  • 49k
14 votes
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Is this explanation for the SpaceX 1-Sept-2016 anomaly plausible?

Edit Jan 2, 2017: Well, it was a COPV bottle after all. There were buckles in some liners where super-cooled liquid oxygen pooled. From NASAspaceflight article, quoting the results of the ...
kim holder's user avatar
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13 votes
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Liquid fuel / Oxygen proportions

There is indeed a ratio of fuel to oxidizer that yields complete combustion, called the stoichiometric ratio. This produces the most thermal energy from combustion, but for a few different reasons, ...
Russell Borogove's user avatar
13 votes
Accepted

Concerns/challenges with LOX as a regenerative coolant

To answer your first question: one of the main problems with using the oxidizer in general is oxidizing of the cooling channels. Any hot oxidizer has this problem, but oxygen definitively has this ...
Ruben's user avatar
  • 1,154
12 votes

How (actually) do sub-cooled propellants reduce cavitation within turbo pumps and make feed easier?

Cavitation is boiling, in this case it is caused by reduced pressure in the wake of blades. A boiling point is a combination of 2 factors; heat and pressure. If you can't do anything about the reduced ...
Johnny Robinson's user avatar
11 votes

How much liquid oxygen is lost during a Space-X Crew Dragon launch abort?

Calculating how much LOX is lost is going to be an interesting calculation, but I'm not sure we have the data for that. Instead, I'll be focussing on the other part of your question: Is the loss ...
Mast's user avatar
  • 601
11 votes
Accepted

F1 engine turbopump

Short answer: shock loads due to high acceleration of the turbopump shaft rubbing between critical seals and other moving parts fatigue in the impeller section Directly quoting from this link: The ...
Kaan Güven's user avatar
10 votes
Accepted

How do they know how much liquid propellant is in a rocket just before launch?

The shuttle external tanks used liquid level sensors. You can see them on the left side of each tank in this schematic. Source: Page 95 of the old Press Manual Related sensors gained notoriety late ...
Organic Marble's user avatar
10 votes

F1 engine turbopump

The four destructive LOX pump failures had happened at 110, 110.5, 107.7 and 109 sec; this looked statistically significant, but after much study the team wrote it off to a freak coincidence. ...
Organic Marble's user avatar
10 votes

Is there any satellite that uses LOX as oxidizer?

Although no satellites have been deployed using LOX for satellite propulsion, there is no fundamental (as opposed to practical) reason why it could not be done. LOX will only boil off until it reaches ...
Woody's user avatar
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8 votes
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Why doesn't carbon fiber overwrapping in LOX catch fire? (watch this video first)

Liquid oxygen mixed with carbon powder has been used as an explosive for mining, see 1, 2. But there has been an explosion in a helium purifier 3. The use for mining required safe explosives, the rate ...
Uwe's user avatar
  • 49k
8 votes

How did JPL detonate a liquid oxygen methane mixture with light?

At low temperatures, the activation energy for pure CH4 O2 oxidization is about 170kj/mole. (See figure 1 here) That’s about 1.8eV per atomic reaction. 1.8eV can be provided by 688nm red light, or ...
Bob Jacobsen's user avatar
  • 12.7k
8 votes
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Was liquid ozone + fluorine ever tested as an oxidizer? Ever with jet fuel?

A not up to date answer but in 1972 J Clark in Ignition writes that cryogenic Oxygen+Ozone was investigated and found to be relatively stable* before use but having some exciting properties for any ...
GremlinWranger's user avatar
8 votes

Is it ever normal to vent LOX from spacecraft with active engines? Isn't it a fire hazard?

Note: Original Question: Is it ever normal to vent LOX from spacecraft with active engines? First, to establish the ground truth, on January 13th, 2024 at an address at Starbase in Texas, Elon Musk ...
phil1008's user avatar
  • 5,634
7 votes
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Supply of liquid oxygen (LOX) maintained on the ISS? Kept cold using "space", or refrigerator?

Hard to prove a negative, but no, there is no provision for storing LOX on the ISS. The coldest thing up there is the MELFI, the Minus Eighty Degree Laboratory Freezer (for) ISS. Oxygen (and ...
Organic Marble's user avatar
7 votes
Accepted

Comparison of rocket engines using LH2 & LOX as propellants

There was a large difference in their size, and at the time, they were developed by two entirely different companies. In general, the propellant combination of a rocket engine does not determine its ...
Russell Borogove's user avatar
6 votes

How can the elements involved in loading a LOX tank be involved in an explosion?

Just to mention one facet of this multifaceted problem, any electrical field potential that exists (i.e. items that aren't on a common bias electrically) can and usually will at some point create an ...
Russ Reed's user avatar
  • 119
6 votes

Why isn't LOX/UDMH used in staged combustion rockets now-a-days?

The reason you go with UDMH/NTO F/O pair is storability, i.e. the ability of your rocket or missile to be stored, fully fueled straight from the factory, in a silo or stand on a launch rack for an ...
Meatball Princess's user avatar
6 votes

Why a 900,000 gallons LOX storage tank at Launch Complex 39?

Partial answer: I can identify the manager responsible for the decision, and the date, but not the reason why. LC-39 was the sole topic at a meeting of the Launch Operations Working Group on 18-19 ...
DrSheldon's user avatar
  • 48k
5 votes
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Filling of LOX tanks - 'cryogenic geyser cycling'

A cryogenic geyser occurs when a volume of cryogenic liquid inside e.g. a pipe suddenly boils, propelling the liquid/gas mixture through the pipe and into its destination at high speed. The pipe ...
Hobbes's user avatar
  • 128k
5 votes

How (actually) do sub-cooled propellants reduce cavitation within turbo pumps and make feed easier?

This answer is based mostly on the NPSH link Organic Marble shared (http://www.pumpschool.com/applications/NPSH.pdf) and the various properties you can infer about subcooled LOX. Subcooling lowers ...
Erin Anne's user avatar
  • 11.5k
5 votes
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Is the Paramagnetism of Liquid Oxygen Ever Considered in Engine or Tank Design?

Check out this article and the sources cited: Simulation of LOX reorientation using magnetic positive positioning https://link.springer.com/article/10.1007/BF02908417 Looks like it has been studied. ...
Almaadin's user avatar

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