55 votes
Accepted

Using ozone as oxidizer

The book 'Ignition!' tells the history of propellant research and has this to say about ozone from page 112 available here For it has its drawbacks. The least of these is that it's at least as ...
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  • 2,531
28 votes

Why do CH4 (Raptor) engines produce less soot than RP-1 (Merlin) engines?

As GandalfDDI notes, you always run your engine fuel-rich so it doesn't start running engine-rich. This results in incomplete combustion of the fuel. Methane is a single carbon atom bonded to four ...
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  • 11.5k
25 votes
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Why does the 2nd stage of Falcon 9 need compressed He tanks?

The helium is used to continuously re-pressurise the propellant and LOx tanks as they are emptied. It is stored in a COPV inside the body of the LOx tanks to keep the He at a lower temperature (and ...
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  • 9,844
24 votes

Why do CH4 (Raptor) engines produce less soot than RP-1 (Merlin) engines?

As explained to me (carefully and fully) by a Rocketdyne engineer you ALWAYS run rocket engines fuel rich. If you run lean the oxidizer looks at the metal parts of the engine (remember the engines are ...
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22 votes

Using ozone as oxidizer

Ozone is not stable, storing in liquid form as a solution in LOX requires stabilizers. It will oxidise most metals. A gaseous mixture of ozone and oxygen may decompose explosively. And it is poisonous ...
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  • 1,674
16 votes
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Other than He and N as pressurizing gases

A good pressurizing gas needs to satisfy a few basic properties: it needs to stay gaseous at the temperatures and pressures your fuel and oxidizer are stored at, so that it won't just condense out ...
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12 votes
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There are better oxidizer than oxygen?

This depends on what "better" is. But let us talk about fluorine. The main point of using it is that turning your hydrogen into $HF$ gives more energy than getting $H_2O$ for pure hydrogen, that ...
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12 votes

Nitrogen pentoxide oxidiser?

Not likely N2O5 Well, the stuff IS a very strong oxidizer. But considering that the solid form is a hard white salt-like substance, and it melts at 41C, and boils at 47C, so it can be a wee bit tricky ...
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10 votes
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Could H₂S₂O₈ (peroxydisulfuric acid), made in the clouds of Venus, be used for making a propellant?

The problem in making propellant on Venus, is surely in finding the fuel, rather than the oxidizer. Oxygen can be made by electrolyzing $\text{CO}_2$ if necessary and while $\text{S}_2\text{O}_8^{2-}$ ...
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10 votes

HTP as oxidizer for main propulsion

HTP has been used as an oxidizer before. Kind of. See BLACK ARROW and the rest of the British keroxide. Turns out HTP by itself isn't a great oxidizer, but when you catalyze its decomposition into ...
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  • 9,800
9 votes
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Why does Juno use "mixed oxides of nitrogen" oxidizer for propulsion? Which ones?

MON according to Wikipedia: Mixed oxides of nitrogen (MON) are solutions of nitric oxide (NO) in dinitrogen tetroxide/nitrogen dioxide (N2O4 and NO2). The addition of a small amount of nitric ...
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9 votes

Disposition of the Oxidizer Tank in Rockets with Autogenous Pressurization

If the question is whether such a system is feasible, the answer is yes, it is 100% feasible, because STS used this exact system. The LOX and LH2 tanks in the ET were pressurized on the pad by GSE-...
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8 votes
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What are the advantages of Ox-rich staged combustion?

According to the super-detailed and very informative NASA-CR 165404 Fuel/Oxidizer-Rich High-Pressure Preburners, the primary advantages of hydrocarbon-fueled oxidizer-rich staged-combustion engines is ...
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7 votes

Why aren't airbreathing SRBs a thing?

You'd need a complex intake: it has to be closed during ignition, with a large closing force (otherwise you'd have half the thrust going out the intake), then it has to move out and keep changing its ...
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  • 121k
7 votes

What are the energy-to-mass ratios of some fuels/oxidizers, when including the oxidizer?

First we have to go back to the chemical equations, and this time, include the standard enthalpy of combustion. Hydrogen: 2 H$_2$ + O$_2$ → 2 H$_2$O + 572 kJ/mol Methane: CH$_4$ + 2 O$_2$ → CO$_2$ + ...
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  • 4,324
7 votes
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Are oxidizer to fuel mixture ratios based on mass or volume?

It's always by mass but there's one additional problem that rockets pretty much never use stoichiometric oxygen to fuel ratio (O/F) that you'd expect if you calculated molar mass of propellant ...
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7 votes

Could H₂S₂O₈ (peroxydisulfuric acid), made in the clouds of Venus, be used for making a propellant?

Peroxydisulfates and peroxydisulfuric acid itself would be a bad choice for rocket oxidizers for several reasons: H2S2O8 is actually a solid with melting point of 65°C, therefore unsuitable for ...
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  • 2,145
6 votes
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Is a fluorine/hydrogen engine feasible for use in space?

The safety-related costs of developing, testing, and fueling fluorine-oxidized rockets outweigh the costs of building slightly bigger and less efficient rockets using hypergolics or LOX. In launcher ...
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6 votes
Accepted

Could you use Helium as an oxidizer?

Helium is a noble gas, meaning it does not react with other atoms. In fact, it is the least reactive of them all. No compounds containing helium has ever been found, although some of the heavier noble ...
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6 votes

There are better oxidizer than oxygen?

Besides pure oxygen, several other oxidizers in theory have better performance with hydrocarbon fuels, but none of them are used because of stability, toxicity and price issues. But let mention some ...
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  • 2,145
6 votes

Why can I not use stoichiometry to calculate the O/F ratio of my rocket?

Rockets frequently (potentially even usually) are not operated stoichiometrically, as this tends not to be the most efficient operating point. The most extreme example is that of the H2/O2 rocket, ...
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  • 7,746
6 votes
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What is the products of a catalyzed reaction between Hydrogen Peroxide and Ethanolamine with Copper(II) Chloride?

TL;DR: The result will probably be mostly water with significant proportions of carbon dioxide and nitrogen gas. Small proportions of copper(II) oxide and hydrochloric acid may also be released. There ...
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6 votes

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 ...
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5 votes

Why does Juno use "mixed oxides of nitrogen" oxidizer for propulsion? Which ones?

The use of MON, as distinct from N2O4, arose because the latter can cause stress corrosion cracking (SCC) of titanium alloys. This was first observed in the 1960's during the development of the Apollo ...
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5 votes
Accepted

Propellant filling rate in propellant tanks

I probably shouldn't answer this question, then again I can't vote to close because it is to broad and ambiguous, so I will try and give an suitable answer to help the OP out. First aspect: What is ...
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  • 974
5 votes

How long can a vehicle stay fueled before the liquid oxygen gets too warm?

They're subcooling the LOX in order to get more oxygen in the tank. The lower temperature translates to something like 3% more oxygen (by weight) in the same volume. When the LOX warms up, it expands ...
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  • 121k
5 votes
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How long can a vehicle stay fueled before the liquid oxygen gets too warm?

Normal vehicles that use LOX, use it at the normal temp (-183C) and what they do is let the LOX boil off, and refill it right up to the latest possible moment their hardware allows. The Falcon 9 1.1 ...
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  • 76.4k
5 votes

Disposition of the Oxidizer Tank in Rockets with Autogenous Pressurization

In describing an instance of an autogenous pressurization system, Appendix E of A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs (downloaded from: http://www....
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  • 1,408
5 votes

Can LOX containing hydrogen peroxide be used as an oxidizer for a liquid fueled rocket?

Sources here and here, see also Supply of liquid oxygen (LOX) maintained on the ISS? Kept cold using “space”, or refrigerator? A quick check via google for "liquid oxygen with hydrogen peroxide" ...
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