# Questions tagged [fuel]

Questions about rocket oxidizer, propellant, reactive mass, or other fuels used in spacecraft or rockets.

33 questions with no upvoted or accepted answers
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144 views

### What rocket uses the largest percentage of Fuel/Oxidizer before liftoff?

inspired by this question: How much propellant is used up until liftoff? which asks how much propellant (fuel/oxidizer) a typical rocket uses before liftoff. What has been or is the most non-typical ...
126 views

### Why do Russian rocket engineers call C₂H₈N₂ “heptyl”?

Unsymmetrical dimethlyhydrazine or "UDMH" is a propellant which has been used by Russian, American, European, Chinese, and Indian rockets. Russian rocket engineers nickname it "heptyl". Why was this ...
165 views

### Falcon 9: how much fuel is left on a booster after stage separation?

If the booster attempts either land or sea landing, how much fuel (RP-1 and LOX) is left in its tanks right after stage separation? Recently, I have heard numbers as high as 30% of its total tank ...
495 views

### How long does it take to chill the LOX and RP1 for Falcon 9 V1.1 Full Thrust?

The new version of the Falcon 9 v1.1 Full Thrust, or as SpaceX would like everyone to start calling it "Falcon 9", uses super cooled LOX and RP1 to improve the density of the fuel for better ...
2k views

### Propellant mass calculation

I have been given the following problem: To solve it I used the formulas: $v_e = I_{sp}.g_0$ $M_{propellant} = (e^{\Delta_v/v_e} - 1).M_{final}$ And I assumed that the apogee kick manoeuvre was ...
153 views

### What is the droplet size that is desirable for pintle injectors?

The pintle injectors tend to generate droplets after impingement of the fuel and the oxidiser stream and I understand that the droplets will be premixed. In such a case, even a larger premixed ...
71 views

### Cooling an aerospike spike via “fuel diversion”?

My question is, could an aerospike be cooled via diverting a very small quantity of your fuel (fuel used since it has a higher heat capacity than oxidizer and won't, you know, turn your engine into an ...
157 views

### Are there examples of a spacecraft designed for transitions from supercritical to liquid+gas mixtures?

The question What happens when supercritical fuel tanks deplete below critical point? suggests some possible scenarios when the pressure of a tank is in danger of dropping below the supercritical ...
84 views

### Maximum speed of rocket propellant flow?

In reading this question (Limiting factors of liquid rocket engine thrust), it prompts me to ask if there is an upper limit in how fast the propellant/oxidizer can be pumped into a combustion chamber ...
107 views

### What fuels would make refueling in space more dangerous/complicated?

I saw the question: Has in-space refueling been done? And was actually beginning to wonder, is refueling and transferring propellant dangerous in space? I understand that this would most likely be ...
143 views

### Does the pressurization of tanks prevent “liquid sloshing” during maneuvers?

I'll be the first to admit I know little to nothing about fluid dynamics, especially in a pressure vessel. I was wondering how pressurized rocket fuel tanks don't cause weight-distribution problems ...
102 views

### How much fuel is left in InSight?

InSight probably landed with some fuel margin. Unless it was vented/burned on landing (maybe not a bad idea considering potential leaks down the road), is there some left ? Do we know the ISP of ...
38 views

### Storage density of a Deuterium-Helium 3 fusion pellet

in a series I am working on I will be using a D-He3 fusion drive system (similar to the one in the expanse according to Project RHO). I am under the assumption that the fuel will be stored in a pellet ...
138 views

### Pressurization line (Helium to LOX tank line) chilling while pressurizing LOX tank

I have read that in rockets and launch vehicles Helium is used for the pressurization of propellant tanks. What temperature Helium is stored at? If Helium is stored at room temperature then while ...
122 views

### Are there any situations where hot rather than cold propellants might be advantageous?

Given that cryogenic fuel and oxidisers exist, I wonder if the reverse is workable. Are there fuels or oxidisers that have been considered for rockets that must be kept hot to be usable? By hot I ...
175 views

### Does LOx stay as liquid when entering combustion chamber?

Given the heat from combustion and increased temperature, would the LOx still be in liquid form after emanating from the injector? Or will it instantly transform into gas? Are injectors cooled using ...
153 views

### Hypergolic slugs with gaseous reactants

Based on points raised in this question about hypergolic slugs. My understanding of a hypergolic slug is that it is a solid or a liquid on a paper patch placed in the combustion chamber and it will ...
115 views

### Would a low pressure container lower hydrogen leakage in space?

Hydrogen, for rocket fuel, tends to leak even through metal containers. Launchers carry hydrogen cooled to liquid in order to save storage space for aerodynamical reasons, but that is unnecessary in ...
34 views

### Where could I find more propellant combustion charts for more different/more broad examples/numbers?

So after asking how I could calculate this kind of propellant combustion charts for different fuels/oxidizers and other ratios and other stuff and getting some really good answers, especially from ...
67 views

### Is there any way to get better performance from an NTR with non-H2 propellant?

Related: Is there some fundamental limitation that would prevent steam-powered rockets from reaching space? Thermal rockets, including nuclear thermal rockets, work best with minimal molecular weight ...
75 views

### Is it feasible to take liquid Helium in a Pressure Fed System?

Can liquid Helium be flowed through a heat exhanger to increase its temperature and pressure which will further pressurize fuel-oxidizer tanks.
206 views

### How to size Solar Array for Mars Surface

Good morning everyone, I am working on a project for my university where we need to perform a PrePhase A study for a Mars Infrastructure for Propellant production as a means of support for future ...
781 views

### Could Sodium metal be used in rocket fuel?

For instance, I read that the Hercules X-265 rocket motor used in the Sprint missile was a solid double base propellant that used nitrocellulose with zirconium metal staples and nitroglycerin as a ...
57 views

### Can Chemical Engineer work on something related to space?

I am an undergraduate student (scientific section) living in Qatar. I have a big interest in astronomy and astrophysics and have participated in the IOAA (International Olympiad on Astronomy and ...
34 views

### Was General Doolittle involved in the invention of RP-1?

James Doolittle is most famous for leading the 1942 air raid on Tokyo. However, between the world wars, he earned a doctorate in aeronautical engineering from MIT, became the manager of Shell Oil's ...
67 views

### Could rocket fuel be mass produced in Ceres?

According to NASA rocket fuel Mars Liquid methane could be used as the fuel, produced from carbon dioxide and water found on Mars. If NASA is "working on it", there has to be many technical ...
40 views

### How does a NTR with an afterburner perform at a stoichiometric mixing ratio?

The LANTR entry at Encyclopedia Astronautica describes how a sample nuclear thermal rocket performs at various mixing ratios of LH2/LOX. It does however stop before reaching the stoichiometric ratio ...
84 views

### How does the inter-propellant seal works in kerosene/LOX and UDMH/NTO rockets?

I get that the inter-propellant seal on the SSME LOX HP pump is simply a series of cascading regular seals trying to eliminate bleed-through by venting and letting boil at each stage, so that when ...
56 views

### Which is preferred for liquid atomization - gas & liquid shear or liquid & liquid shear?

For generating a spray of droplets, liquid need to be disintegrated/atomized through shear forces. Typical injectors in IC engines and aircraft use shear between gas & liquid at the phase ...
490 views

### How much fuel is necessary for 2nd stage of Falcon 9 rocket to land?

What is the fuel mass nedeed for the 2nd stage of Falcon 9 rocket to land, how much compared with its total fuel mass that it has? Or how much delta-v is necessary? Would it be able for Falcon 9 to ...
181 views

### Are there any complications of the position of the oxidizer injector on Orbitec's vortex rocket engine?

Orbitec's vortex rocket engine injects oxidizer from near the nozzle up the wall of the engine chamber in a vortex. The oxidizer injector being in this position seems unusual. Are there any ...
104 views

### Hazardous Propellant properties

is there a standard how NASA/ESA categorize hazardous propellant properties like flammability, toxicity, corrosiveness etc? Any links, papers, discussions would be greatly appreciated! Regards ...
58 views

### Could the issue of engine coking be solved with corrosive additives?

Many fuels will start to coke, that is they solidify when they're exposed to heat, such as in a regenerative cooling loop, particularly those that are commercially available like petroleum. Are there ...