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Questions tagged [fuel]

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

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2answers
3k views

Using ozone as oxidizer

The bond energy of $O_2$ is 498kJ/mol. The bond energy of $O_3$ is 364kJ/mol. That means the energy to break up the particles into 3 moles of monoatomic oxygen (which then binds with fuel to release ...
38
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1answer
6k views

Do booster stages run out of fuel, or are they purposefully shut off?

When an expendable booster rocket stage nears the end of its burn, does the guidance computer shut the engine(s) off at a certain velocity/altitude for the mission, or does the stage completely ...
33
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4answers
9k views

Why is there a hole in solid rocket engines?

I would like to find out why there is a straight hole down the middle in all solid rocket engine motors. I thought it only makes sense in hybrid engines where pure oxygen needs to be blown down the ...
32
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3answers
7k views

What is the primary reason for SpaceX motion to have astronauts board Dragon before fueling up the rocket?

News piece: NASA supports SpaceX plan to fuel rockets with astronauts on board. The move is criticized by many as unnecessarily dangerous. From what I understand though, it shouldn't be necessary - ...
31
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6answers
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Why did it take so long for methane to be used as a rocket propellant?

SpaceX have put methane on the map as a rocket fuel, but they weren't the first to consider its use. The first experiments in building a rocket engine that uses methane date back to 2007. Now methane ...
31
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3answers
13k views

Why are hydrogen-fluorine fuels not used for rockets more frequently?

Many rockets use hydrogen- and oxygen-based propellants as fuel. Why are hydrogen-fluorine fuels not used? It has a specific impulse of 390 seconds, higher than hydrogen-oxygen combustion (360 ...
30
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3answers
4k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
26
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3answers
4k views

Does the NK-33 engine require subcooled kerosene so cold that it turns to wax?

It was mentioned in this answer and in several other places on the internet that the kerosene fuel used by NK-33 engines needed to be subcooled enough so that it reached the same density as the LOX, ...
22
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1answer
2k views

Why is fuel ratio different for upper stage of a rocket?

After reviewing this amazing graphic posted in another question: I noticed that the LH/LOX ratio is slightly different in the Second and Third stages. The mass stoichiometry of the reaction: 2 H2 + ...
22
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1answer
973 views

What was the result of the propellant predictions in the last chapter of “Ignition!”?

In John D. Clarke's Ignition! (1972), the author spends the last chapter making predictions about the future of liquid rocket propellants. I thought these were very interesting, but I realize the book ...
21
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7answers
4k views

Pre-mixing cryogenic fuels and using only one fuel tank

A methalox engine is fed from two cryogenic fuel tanks. Why can't the methane and oxygen be mixed as gases, in the desired proportions, and then chilled to a temp that liquefies both? From a single ...
20
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3answers
4k views

Reasons why liquid anhydrous ammonia fuel chosen for the X-15? Has it been used in other rocket engines?

Both Flight 90 and Flight 91 of the North American X-15 crossed the Kármán line, reaching altitudes of 106.01 and 107.96 km respectively. Both flights were piloted by Joseph A. Walker, who became in ...
20
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1answer
1k views

Why is the Angara rocket called eco-friendly?

I've read several articles about the new Angara rocket, that called it clean/eco-friendly. I know it runs on kerosene (and LOX), which is not super-toxic like hydrazine, but still... it's polluting ...
19
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4answers
716 views

Could a rocket engine be designed to use different fuels? (Like LOX+H2, LOX+CH4)

I'm obviously not a rocket scientist, so this might rank among the stoopidest questions around here. I wonder if it is feasible to design a rocket engine which could be reused in space by refilling it ...
19
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3answers
2k views

Could I home-brew my own rocket fuel?

RP-1 is highly refined kerosene. If I bought a supply of commercial-grade kerosene, by what process could I convert it to RP-1, And, while I'm at it, do I have any good choices for non-cryogenic ...
19
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3answers
4k views

Could 3D printing be used to achieve perfect grain geometry of solid and hybrid rocket motors?

Solid cores, either for solid-fueled of hybrid rocket motors, use various propellant grain geometries to achieve thrust curve needed. For example, some of these could look like:    &...
18
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3answers
2k views

How are fuel tanks filled with cryogenic hydrogen?

Cryogenic hydrogen can react with the atmospheric Oxygen to produce an explosion: as well as being cold enough to liquefy (and possibly solidify) atmospheric oxygen, which can be an explosion ...
17
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5answers
1k views

Is atmospheric skimming for propellant feasible?

A recent comment in a discussion of satellite refueling mentioned the possiblity of a spacecraft dipping into the atmosphere from LEO to obtain oxygen. Similarly, the science fiction RPG Traveller ...
16
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3answers
2k views

In a cryogenic fuel rocket, at what pressure is the fuel injected into the engine?

The pressure in the Space Shuttle's main engines must be very high to get the vehicle off the ground (with the SRB assist, of course). With such high pressures inside the engine, how do you inject ...
16
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3answers
1k views

How are cryogenic rocket propellants delivered to the launch pad?

I work at a university that gets LN2/LHe (liquid nitrogen and helium) delivered a couple times a week by a large tanker truck outside my office. It seems to work well enough to deliver a couple tons ...
16
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1answer
54k views

How much fuel was used for a Space Shuttle launch?

Many of us have watched the launch of a Space Shuttle space ship, I think: a giant red rocket, some smaller, and the way smaller space ship on the red one. It reaches Mach 23 to be able to leave ...
16
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2answers
491 views

Can solid fuel leak?

Recently the ISRO GSLV launch was called off on account of a fuel leak. Other launches too have, on occasion, been called off for similar reasons. Fuel used to launch a craft to orbit may be solid, ...
16
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2answers
2k views

How feasible is it to use aluminum and liquid oxygen as future propellant sourced from the moon?

I was looking into whether there would be any way to source propellants from the moon itself in support of a future base and space stations in cis-lunar space. I found two documents exploring how ...
16
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2answers
541 views

How does the launch risk posed by plutonium compare to the launch risk posed by propellants?

For outer solar system exploration, virtually the only feasible power subsystem are Radioisotope thermoelectric generators (RTGs). These include plutonium, which may carry considerable risks (see ...
15
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3answers
4k views

Petrol as rocket fuel

Why are petrol and diesel not used as rocket fuel like kerosene ? Which properties make them unfit for use in rocket fuel ?
14
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3answers
4k views

Is the supercooled LOX used in Falcon 9 Full Thrust a first?

One of the changes made to the Falcon 9 v1.1 Full Thrust was using supercooled liquid oxygen at 66 K (-340 F) as well as chilled RP-1. I've seen various claims that this is a first in the industry. ...
14
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2answers
1k views

How was reserve fuel calculated for the Apollo missions?

A quick follow-up to How much fuel was used for a Space Shuttle launch? My memory is a little foggy; I seem to recall reading the Apollo 11 mission commander depleted his reserve fuel landing Eagle. ...
14
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1answer
11k views

Why is TEA-TEB chemical ignition used instead of spark ignition?

Both the Saturn V and the Falcon 9 use TEA-TEB to ignite their kerosene-fueled engines. TEA-TEB is pyrophoric, igniting spontaneously on contact with air. This poses handling issues; it must be stored ...
14
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1answer
1k views

Changes made to ISRO GSLV-D5's CUS and FBTP since GSLV-D3's LH2/LOX CUS failure to sustain ignition?

The launch of the ISRO GSLV-D5 launching India's GSAT 14 advanced communications satellite (weighing 1,980 kg) is slated for 19th of August, 2013, flying in the GSLV Mk.2 configuration with an Indian-...
14
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1answer
2k views

How long is it feasible to store cryogenic fuels?

Working with liquid nitrogen all day, I am constantly bothered by their boiling away, forcing me to go get more from the storage dewar. Likewise should be the case with any cryogen, e.g. LH2 and LOX ...
13
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5answers
4k views

Can a rocket motor be shut off after ignition?

After ignition, if any problems occur such as fuel leakage, can a rocket motor can be shut off?
13
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1answer
1k views

Why does the 2nd stage of Falcon 9 need compressed He tanks?

It is well known that the rapid disassembly of Falcon 9 static testing started with the rupture of the composite fibres of the copv He tanks. But what is the need to have the composite tanks ...
13
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1answer
2k views

How weak can a propellant be and still get a rocket to space, theoretically?

There was, briefly, a discussion recently of the use of Mentos and Coke to get to space. It wasn't a serious question but pointed to a way of understanding the core of how rockets work. Last year I ...
13
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5answers
2k views

What are the challenges in Falcon 9 “full thrust” (v1.2) with densified propellant?

SpaceX has announced an upgrade to their Falcon 9 rocket, achieving greater thrusts with, as far as I can tell, the same rocket motors (at least, they apparently still call the motors "Merlin 1D"). ...
13
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1answer
1k views

What is a typical energy demand and carbon footprint of a space launch?

How much greenhouse gases are released per kg launched into space, what other energy is needed? For the scope of this question, let's ignore the embedded energy in all the machinery and just look at ...
13
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1answer
1k views

Are MMH and UDMH interchangeable?

Can Monomethylhydrazine and Unsymmetrical dimethylhydrazine be used one in place of another for the class of the existing orbital maneuver engines (with reduced performance may be)? Such as Shuttle's ...
13
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1answer
605 views

At what travel distances are ion engines faster and more efficient than conventional fuel engines?

According to Scientific American (February 2009), ion engines start off slow, but build up speed as they travel. At what travel distance would an ion engine (such as an ion thruster, a Hall thruster, ...
12
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2answers
3k views

Can a rocket refuel on Mars from water?

Can a rocket run only on hydrogen and oxygen? Could a rocket, rover, and electrolysis machine be sent to either of Mars' poles to excavate ice to make hydrogen and oxygen to refuel an unmanned rocket? ...
12
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2answers
2k views

How do rockets keep their fuel in a liquid state?

What are some of the measures engineers would take to ensure that the LOX and other similar fuels are kept below their boiling point during flight?
12
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1answer
1k views

How would the Saturn V have differed if the first stage was also LH2/LOX?

Since both Kerosene (RP-1) and liquid hydrogen (LH2) continue to be important liquid fuels used with liquid oxygen (LOX), something can be learned by comparing how they are used. This is covered well ...
12
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2answers
3k views

Why use Kerosene?

According to SpaceX's website, the Falcon 9 uses kerosene as fuel. According to Wikipedia, diesel fuel beats kerosene in energy density in terms mass by 2.8 MJ/Kg and in volume by 5.6MJ/L, so why ...
12
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2answers
1k views

What is this red gas at the exhaust of the Long March 3B rocket during liftoff?

While watching today's live stream of the launch of the China National Space Administration (CNSA) Long March 3B rocket carrying Chang'e 3 lunar exploration probe and the Yutu rover to the Moon, @...
12
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1answer
438 views

Flying fuel tanks! Which deep-space spacecraft had the largest fuel mass fraction?

The Los Angeles Times' Deborah Netburn just wrote a really nice retrospective; ‘OK. Let’s do it!’ An oral history of how NASA’s Cassini mission to Saturn came to be with plenty of photos and quotes ...
12
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2answers
985 views

Which currently operational orbital launch vehicle achieves highest system-specific impulse?

I'm primarily looking for comparison of currently operational orbital launch vehicles by system-specific impulse, or Issp, and to get a fair impression of achievable rocket propellant performance and ...
12
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1answer
337 views

Do the propellants ionize in chemical rockets?

When combustion takes place in a chemical rocket (LOX/LH2), do the gases ionize due to high temperatures? If they do, how do they get around the problem? Ionization is a waste of energy I believe, ...
12
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1answer
206 views

Are there any proposals to vacuum up gases in orbit for use as propellant?

Space stations like the ISS orbit at an elevation that puts them squarely in the Thermosphere, and while this has extremely rarefied gas (which is probably more accurately a plasma at many times), it ...
12
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1answer
523 views

Does the Soyuz spacecraft chemically stabilize the hydrogen peroxide (H2O2) to remain ISS-dockable for 200+ days?

Hydrogen peroxide from the local shop (dilute, 2-3%) sometimes has a stabilizer to slow it's breakdown rate and increase it's "shelf-life", since we'd like to keep it around the house on our shelf for ...
11
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1answer
3k views

Do rockets deplete the oxygen on earth?

When we use our rockets in space, are we using up a fraction of the finite oxygen here on earth? I'm assuming that it's a negligible amount at our current rate of space travel, but could this ...
11
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2answers
1k views

Nuclear thermal rocket specific impulse calculation uses 1 amu, is that wrong?

Following the parameters in the Wikipedia nuclear thermal rocket article, it seems to paint somewhat of a shaky world view. Consider these quotes: Current (2010) 25,000 pound-thrust reference ...
11
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2answers
683 views

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

On February 28 2016, Falcon 9 attempted a second launch for its 22nd flight. However, it was put on hold for about 20 minutes at T-01:33 and had its countdown reset to T-11:44, giving a total of about ...