# Questions tagged [fuel]

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

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### Why RP-1 and not Methane for Falcon 9's Merlin engines?

I've seen methane described as the best of both worlds---the worlds being hydrogen's energy density + pain-in-the-ass factor and RP-1's lower energy density + ... ease of use? And this has me ...
188 views

### energy needed to accelerate in space

I was thinking about possibility of cargo transport between, say, earth and mars when a “pusher” accelerates propulsion-less cargo vessel, which is catched and decelerated at the other end of ...
32 views

### SpaceX Dragon: How many fuel tanks?

I've read that Dragon carries 1380 kg of MMH + NTO propellant. This mass would be split among the various tanks, and I'm wondering---how many of them are there? Pictures from the manufacturing floor ...
100 views

### Can Pyroxene and other silicon compound be used as a theoretical spacecraft fuel?

I have been reading this patent : https://patents.google.com/patent/US3137599A/en This lead me to this paper: https://www.jstor.org/stable/44682837?seq=1 The first uses Polysilane, which basically ...
41 views

### Is CO + O ==> CO2 a possibility for propelling rockets off Mars? [duplicate]

Perseverance, the Mars rover, includes an experiment called MOXIE. This is a technology demonstration to show that Mars' atmospheric carbon dioxide can be broken into carbon monoxide and oxygen. ...
3k views

### Why is an inflatable balloon inside a fuel tank not used to prevent fuel from “sloshing around”?

After seeing all the Starship failures, having something with a membrane keep things in place seems like an obvious solution. Has it been considered or tested - or do we simply lack a material that is ...
206 views

### Why is hydrogen better than helium as remass?

I just watched a very good YouTube video on why nuclear engines might be useful, and it also goes into why Hall Effect thrusters are super good at squeezing obscene ISP out of things. During the video,...
5k views

### How do you reliably blow up a rocket that was built not to explode?

NASA, and I'd imagine most space agencies around the world, demands abort systems of its commercial partners capable of destroying a rocket should it venture too close to populated areas. Note that ...
97 views

### Could another fuel be used in the SpaceX Starship header tank?

A memory of hexane and water in a separatory funnel brought to mind the issue of helium and LNG in the header tank while the Starship flips and does its powered landing. There was discussion of the ...
145 views

### If high-test peroxide is most stable when pure, why are most uses of it in rocketry at lower concentrations?

Per the Wikipedia article for High-test peroxide: Hydrogen peroxide becomes more stable with higher peroxide content. For example, 98% hydrogen peroxide is more stable than 70% hydrogen peroxide. ...
39 views

### What is the O/F ratio of ethanolamine/H2O2?

I've just read this question What is the products of a catalyzed reaction between Hydrogen Peroxide and Ethanolamine with Copper(II) Chloride? and although its a very good question and an excellent ...
68 views

### Potential Fusion Drive system calculation issue

I will start off by saying that this is an entirely hypothetical drive system with plenty of handwaving and optimistic physics. My question I think is fairly simple and may just be something that ...
207 views

### What happened to tripropellant rockets?

IIRC, tripropellant rockets can deliver superior performance compared to bipropellant rockets (at the cost of added complexity). Now, I know that there is the Li/H/F combo, but it isn't used because ...
76 views

### How do I calculate thermochemical properties of mixed gases?

I'm working on a rocket project, and my design of engines is stalled. I need to be able to calculate the Cp, Cv, and R for mixtures of O2/CH4 (stoichiometric or fuel-rich mix) and CO2/H2O (result of ...
180 views

### Have any rocket fuel systems actually been explosive, and could have detonated proper?

Never mind that this is the 18th question to have the rocket-explosion tag. To the question "Would the Dragon escape pod have survived this event?" asked about the AMOS-6 mission, Elon Musk ...
144 views

### How much power do radiation-based engines produce

I heard that the Voyager satellites used a radioactive source to power the computer and sensor systems. How much power can this technique produce nowadays? Could it power, say, a fighting robot? ...
112 views

### What is the practicality of using sub-cooled propane in combination with HTP in an amateur engine design? [closed]

Using sub-cooled propane, at approximately -90°C (b.p. -42°C at STP) in combination with >80% hydrogen peroxide, can any meaningful gains be made, whilst considering that this fuel mixture would be ...
89 views

### How much easier is it, to explore space from a low orbit satellite, than from Earth?

Note: in this question I'm considering cost in both money and fuel terms, and looking for answers that consider both. So we know that using chemical rockets to reach the moon, or further into space, ...
2k views

### Rocket fuel cost to launch 1 kg to orbit

I have 2 questions about the cost of liquid rocket fuel to launch (anything) to LEO orbit. Let's assume we use fuels used in commercial spaceflight today (probably LOX+LH2 or LOX+RP-1 etc.). What is ...
536 views

### Pressure levels inside rocket liquid oxygen tanks?

What is the pressure levels inside rocket liquid oxygen tanks, at launch time? The question is for the minimum and maximum (known) levels of pressure inside such tanks. I am asking for any rocket ...
48 views

### How stable is ozone as a compressed gas?

I have heard that liquid ozone is violently unstable, making it unusable in any meaningful concentrations. Would using it as a compressed gas partially solves the problem? What is the mechanism of its ...
72 views

### Why shouldn't Chang'e 5's lander's propellant freeze?

We have just measured the shape of the crater that the returner landed on, which is part of the scientific data collection. Then the returner will [put on a] 'new warm coat' to prevent the remaining ...
1k views

### When has hydrogen peroxide been used in rocketry?

Peroxide is apparently a very good propellant, but I can't seem to find any instance of it being used. Has it ever been used and if not, why hasn't it? What's its downsides?
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### Where would one find information on the fuel properties (temp, max ISP) of non-conventional rocket fuels?

Yesterday's Starship landing saw at least one Raptor burning copper. Given that copper oxidizes with oxygen at the temperatures and pressures found in a Raptor combustion chamber, what properties does ...
120 views

### Burning Up Hydrazine and N2O4 for Safety

Sadly, all the "good" (storable, hypergolic, and having good performance) rocket fuels and oxidizers -- Hydrazine, methylated hydrazine, nitrogen tetroxide, and fuming nitric acid -- are ...
68 views

### What happened to continuously-applied heat barrier coatings in engines?

In Ignition, Clark describes an interesting approach to thermal control in rocket engines using oxygen as an oxidizer and hydrocarbon fuel: A small amount (few percent) of silicone oil or another ...
88 views

### Dinitrogen tetroxide decomposes to nitrogen dioxide at room temperature, but rockets that use it are usually said to use N2O4 and not NO2 - why?

To the best of my understanding, both dinitrogen tetroxide and nitrogen dioxide are usable and perform quite similarly as oxidizers, but rockets that use either are almost always said to use ...
65 views

### Will you be having rubber or wax with your peroxide? (hybrid engine fuel tradeoffs)

Hybrid engines offer some practical advantages and some budgetary ones that can offset lower ISP, including potentially safer solid fuel to store and non cryogenic storage of some oxidizers like ...
287 views

### Why did the Space Shuttle dump excess fuel from the external tank?

In his recent video, Scott Manley mentions that after reaching orbit, the Space Shuttle would dump the excess fuel left in the External Tank before jettisoning it: ...
38 views

### How much hydrazine does an Iridium satellite start with? How much does it use per year?

Iridium satellites use hydrazine and the spacecraft are expected to last at least 15 years. How much hydrazine do Iridium satellites start with, and if possible, roughly do they use per year?
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### Using water as a high density storable hydro-lox propellant

Hydro/lox is an excellent fuel choice and has been used in many engine/rockets with high ISP requirements, however, the two biggest drawbacks of the propellant are its density and boil-off. Could this ...
456 views

### Does peroxide spontaneously decompose when introduced into hot combustion chambers?

I understand that hydrogen peroxide (HTP) can be decomposed into superheated steam and oxygen using a catalyst, but I haven't been able to find any information on whether or not it will decompose in ...
84 views

### Preventing hard starts using varied propellant/ O/F ratio?

From what I've heard, hard-starts are a very common, particularly in less refined amateur rocket engines, and the only way to avoid them is to either start the engine on an extremely low flow rate or ...
82 views

### Which fuel cell fuels have been demonstrated in space?

Combination of fuel cells and electric motors - whether it has been used as part of an electric pump-fed cycles? gives a short summary of fuel cells and lists the following energy-containing fuels ...
91 views

### Why didn't propylene fly? (Vector)

Ars Technicha's Rocket Report: SLS has technical problems, Vector—yes, Vector—is back links to Vector restarting operations under new ownership which says: One thing they did wrong was the technology ...
2k views

### Why is butane never used in rockets as fuel?

From what I know, it seems good, so why does no one use butane as a rocket fuel?
3k views

### Why do the contents of the Space Shuttle External Tank not match the mixture ratio of the engines?

The Space Shuttle External tank contains: 629,340 kg of liquid oxygen 106,261 kg of liquid hydrogen. That's an oxidiser to fuel ratio of 5.92 Meanwhile, the Space Shuttle Main Engine has a constant ...
208 views

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

I am attempting to calculate the oxygen to fuel ratio (O/F) for my hybrid rocket engine (paraffin wax and gaseous oxygen). I know I can use the oxidizer to fuel equation to calculate this, but my ...
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### At what time is the Falcon 9 loaded with fuel?

How long before launch are the fuel and oxidizer loaded into a Falcon 9 rocket? And how much time does it take to load it?
209 views

### Will mining water on Bennu not be more economical than collecting it near the south pole of the Moon?

Bennu is a carbonaceous asteroid that is currently accompanied by the OSIRIS-REx spacecraft that will take samples from it to return to Earth. Its diameter is 490 m. and it is slightly denser than ...
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### 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 ...
1k views

### Have there been rocket engines designed for diesel? What ISP theoretically possible?

Have there been rocket engines or even test engines that have used diesel as a fuel? If so, what oxidizer had they used and what ISP did they achieve? If not, is it possible to say what ISP is at ...
1k views

### In what ways is helium used on modern launch vehicles?

Helium is a fairly rare material and does not remain in the atmosphere. I'd like to know the uses of helium on modern launch systems? Do most launch vehicles use helium in several different ways, or ...
805 views

### Getting back from the Moon

This link describes the way back from the Moon surface to the orbiting spacecraft. But how could that spacecraft get back to the Earth? It is a long journey. How much rocket fuel would be needed, in ...
178 views

### Did rockets use turbopumps prior to the V-2?

Did the liquid propellant rockets before V-2 use turbopumps or were their fuel tanks pressurized with gas? Or perhaps were their engines gravity-fed?
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### When was liquid hydrogen used for the first time in rocket engines?

When it was the first time the liquid hydrogen was used in a rocket engine? I mean for space launches, but it would be interesting to also know about first uses in experimental engines, in military, ...
2k views

### When was liquid methane used for the first time in rocket engines?

When it was the first time the liquid methane was used in a rocket engine? I mean for space launches, but it would be interesting to also know about first uses in experimental [rocket] engines, in ...
191 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 ...