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Questions tagged [fuel]

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

26
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3answers
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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, ...
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 ...
6
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1answer
453 views

How do rocket propellant combinations rank in terms of “brightness”?

While a booster on the shuttle had a bit more than twice the thrust of the shuttles engines at take-off, I'd venture a guess that it produced on the order of a thousand time more visible light. In ...
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:    &...
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 ...
10
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3answers
2k views

What are the phases of ignition (and flameout) of a liquid fuel engine?

As I observed ignition of several rocket engines (Shuttle, AMDE, Lynx Suborbital, Saturn V) they all come through a couple phases - emitting various vapors, unfocused flame, etc, before the proper "...
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 ...
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?
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 ...
4
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1answer
869 views

Vector-R's LP-1 and -2 engines use liquid propylene as fuel with LOX, advantages and distinctions from kerosene?

@gwally's answer highlights the company Vector Launch Inc. and their Vector-R rocket, which uses three LP-1 18,300 lbf engines on the first stage and one LP-2 1,000 lbf second stage engine to put ...
6
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2answers
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Pros and Cons of LH2/LOX vs Other Fuels

As I stated in the answer to another question, LH2 suffers some serious drawbacks compared to other fuels. Off the top of my head, they are Extremely low density, resulting in: Lower mass-fraction ...
5
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2answers
1k views

Is the pressurization of propellant tanks necessary for structural integrity?

Propellant tank pressurization is a critical aspect of liquid propellant rocket design. Many designs use high pressure helium, heated and recirculated, however the propellant gases themselves can be ...
16
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2answers
542 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 ...
9
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4answers
7k views

Why do pressure-fed systems have to be pressurized with helium or nitrogen?

This is something I just don't understand. The way I see it, propellant can be pressurized all on its own in the tank. Just pump a lot of the stuff in there and make sure the tank is strong enough. ...
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 + ...
9
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1answer
2k views

How does an Electric Solid Propellant rocket work?

I saw the section in Wikipedia about Electric Solid propellants but I can't figure out what it really is, and how it works. It sounds like a solid propellant rocket that you can start and stop ...
12
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1answer
528 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
312 views

Why is one of these two concurrent fuel-dump spirals blue?

This comment mentions the amazing double-spiral event seen in the night sky from Norway that Wikipedia calls the 2009 Norwegian spiral anomaly. The Gizmodo article Giant Mysterious Spiral Takes Over ...
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-...
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 ...
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. ...
6
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1answer
276 views

Could oxygen be used in a resistojet in a vacuum environment?

Resistojets heat a compressed gas or vaporize a liquid to expand it through a nozzle for thrust. They improve a bit on the performance of cold gas thrusters. This experimental water resistojet managed ...
31
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6answers
6k views

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 ...
11
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3answers
572 views

Xenon vs Hydrazine, “Should I Stay or Should I go?” Dawn mission decisions

edit 2: There seems to have been some announcement/extension by NASA (20-Oct-2017), possibly this will shed more light on the issues in this question. edit 1: Several months have passed since this ...
5
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2answers
268 views

Pro/cons of burning propellant in stochiometric ratio?

Several questions and answers here speak of stochiometric ratio. I do understand it is convinient for efficiency (greater ISP). I also read somewhere (I am unable ro find again the reference, it was ...
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. ...
6
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3answers
5k views

Are oxidizer to fuel mixture ratios based on mass or volume?

Wikipedia references the ratio of liquid oxygen to RP-1 as 2.56. Is this based on mass or volume? Are they using some typical combustion chamber pressure?
3
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1answer
225 views

Is there a derivative of LMP-103S, called LMP-103, that has even higher performance?

I found this PDF while searching for any and all info related to LMP-103S, which you can read more about in my related question. In the PDF, if you scroll down to page 4, you will find a chart ...
1
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2answers
420 views

Has (theoretically) metastable metallic hydrogen been considered for use as a propellant?

I'll just point to the following two questions and their associated answers for background: For the recently reported production (January 2017) of metallic hydrogen in the laboratory - what is the ...
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 ...
10
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3answers
1k views

Do any realistic rocket systems use different substances for propellant and fuel?

In his Edge.org Annual Question response, Progress in Rocketry, George Dyson exults in the success of Blue Origin and SpaceX in landing their rockets after pushing them past the Kármán line, and then ...
9
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1answer
1k views

How much propellant is used up until liftoff?

How much of the total propellant mass (fuel+oxidizer) of the first stage/boosters is usually burnt between ignition and liftoff?
6
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1answer
2k views

Would (theoretically) metastable solid metallic hydrogen even need an oxidizer?

In this answer there is discussion of some research on the potential, future use of a solid metallic hydrogen phase that would be metastable at ambient pressure as a rocket propellant. The work is ...
5
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2answers
673 views

What's the specific impulse of a human farts/urination?

I was curious about how effective farting/urination would be as a propulsion system, but I couldn't find any data on the specific impulse of human farts/urination. Could you actually get a couple of ...
5
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1answer
300 views

Why did the “Secretive SpaceX Zuma Launch” make a big “S” or yin-yang shape in the sky?

The Space.com article Strange Sky Spiral May Come from Secretive SpaceX Zuma Launch shows images from this Tweet and this tweet, the second of which was posted by Dr Marco Langbroek (@Marco_Langbroek):...
4
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2answers
282 views

What are some notable cold gas thruster propellants, and why?

Cold gas thrusters are a very simple and reliable form of thruster that operate only by spraying a compressed gas, without any chemical reaction. What are the most common, performant, or otherwise ...
2
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2answers
1k views

How much energy is required to send a payload of 40 t from Earth's surface to LEO?

I am confused with energy requirement equations... Am I anywhere near with my following assumptions: $\Delta v$ from surface to LEO is 9000 m/s typical exhaust velocity $v_e$ = 4500 m/s and mass of ...
1
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2answers
288 views

ULA: bringing propellants from Earth “Avoids Earth's Deep Gravity Well”?

I read SpaceX’s biggest rival is developing “space trucks” to ferry cargo in an orbital economy in Quartz which linked to this April 2016 outline of ULA's view of Transportation Enabling a Robust ...
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 ...
12
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2answers
986 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 ...
7
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3answers
2k views

Overcoming pressure differential to feed fuel into rocket engines

When pumping fuel and oxidizer into a rocket engine, I presume the pump must create more pressure than the inside of the combustion chamber, otherwise the liquid would back-flow. Is this right? Then ...
5
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3answers
2k views

Splitting water quickly to turn a water rocket into a H/O rocket at launch: could it work?

I was just looking at a small but impressive compressed air/water rocket that launches off of a metal rod that runs through the nozzle and spans 3/4 of the length of the rocket. As the team increased ...
22
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1answer
976 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 ...
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
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 ...
11
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1answer
582 views

Is it possible to use zinc powder as a NTR propellant?

The ISP of a propellant is important when mass is the limiting factor; however, that is not exactly the case when launching a rocket. For the first part of the flight, the density of the propellant is ...
10
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1answer
664 views

Use of carbon monoxide as propellant on Mars

Is it possible to use carbon monoxide as propellant for a rocket? For example, carbon dioxide from the atmosphere of Mars could be transformed to carbon monoxide and oxygen via photochemical ...
8
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2answers
629 views

Proportions of a reentering spacecraft as compared to fuel mass

Call this a thought experiment. Spacecraft to Earth orbit and beyond are traditionally launched by means of one or more rocket engines. The fundamental principle is that a rocket moves by expelling ...
6
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3answers
2k views

Combination of liquid hydrogen and liquid oxygen

For the Apollo missions in the 1960s, NASA used a combination of kerosene and liquid oxygen to get the rockets out of Earth's atmosphere. Why did they do that? If you look at the statistics, the ...