Questions tagged [liquid-fuel]

Questions regarding rocket propellant in liquid form, the main type used for chemical rockets.

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ULA's plan for LH2/LOX 2nd stage that can maintain propellant for an extended period of time?

Business Insider's (long) article SpaceX's biggest rival has a 'genius' plan to cut its rocket launch costs more than 70% contains the statements sourced from ULA's CEO Tory Bruno: Vulcan should ...
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Rocket Engine Plumbing: Still don't understand the Full Flow Staged Combustion Cycle

I just found this incredible video KSP Doesn't Teach: Rocket Engine Plumbing and ran through it a few times. It's very helpful in the way it outlines the various issues first, and then designs the ...
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Is it bad if hydrazine freezes on a spacecraft? Is it always kept as liquid, or can it be safely allowed to freeze and then thawed when needed?

After having read this answer I wondered what happens if hydrazine freezes. It looks like it is "normal" and not like water, in the sense that it contracts when freezing, unlike water which expands ...
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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 ...
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How was fuel crossfeed achieved, between the main tank and the Shuttle?

Whenever a fan of Kerbal Space Program mentions the super-efficient 'asparagus staging' in any professional context, the automatic response is 'That won't work. KSP fuel pipes are pure magic.' The ...
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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 "...
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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 ...
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Structural composition of shuttle liquid fuel tank wall

Somewhere I read the shuttle fuel tank kept structural integrity only thanks to internal pressure of the fuel, a'la inflated balloon; empty it would collapse under own weight; and the walls were ...
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6 votes
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How will Robotic Refueling Mission-3's liquid methane tank remain full for six months without any boil off?

Space.com's Lasers, Crystals and 36,000 Worms Will Ride a SpaceX Dragon to Space Station says: To fly on those journeys, astronauts might have to someday harvest fuel from the surface of the moon ...
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How does SpaceX plan to deal with boiloff on the trip to Mars?

Both BFR (Big Falcon Rocket) booster and BFS (Big Falcon Spaceship) are to run on Raptor engines, fueled with liquid methane and liquid oxygen - cryofuels. The trip to Mars will take at least a couple ...
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Rocket explosion compared to kT of TNT; has one ever knocked something over at a distance?

The energy equivalent of 1 gram of TNT is about 1 kcal or large Calorie. For reference, 1 gram of carbohydrates gives us almost 4 Calories of energy (if we are lucky enough to use it and not store it)....
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What actually is RP-1, and how is it different from any other hydrocarbon liquid fuel?

Related: Russian "kerosene" versus American "RP-1", however that's more about the details of specific rocket kerosene specs than rocket kerosene in the context of hydrocarbon and ...
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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 ...
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Problems with the "How to Design, Build and Test Small Liquid-Fuel Rocket Engines" text

For those that have read or consulted the text: How to Design, Build and Test Small Liquid-Fuel Rocket Engines (Rocketlab/China Lake). Otherwise, see steps 10-13 here: https://risacher.org/rocket/...
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How did sloshing prevent the Apollo Service Module from moving safely away from the Command Module and how was this fixed?

The Insider.com article 'We could have lost the Apollo 11 crew:' A once-classified anomaly nearly killed NASA's first moon astronauts, a new book reveals describes a problem during reentry of several ...
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Is methylsilane CH6Si ever considered as fuel in rocketary?

Methylsilane CH6Si seems to have some useful properties for rocket fuel: High hydrogen content, 6 atoms per molecule, 13% of overall mass, High combustion energy, -2612KJ/mol or 56.8 MJ/kg (better ...
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How do they know how much liquid propellant is in a rocket just before launch?

In this answer I wrote: In other words, a few tons here or there could depend on something as simple as the weather, or trying to squeeze a little extra propellant in for a given mission with a tight ...
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Are these sliding ullage bulkheads in the OTRAG rocket? How do they seal?

This answer to Were there any non-state organizations to organize space flight and colonizations in the second half of the 20th century? mentions OTRAG and links to Astronautix's OTRAG page. The ...
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How did JPL detonate a liquid oxygen methane mixture with light?

This answer to Pre-mixing cryogenic fuels and using only one fuel tank quotes John D. Clark's Ignition! Chapter 11: The Hopeful Monoprops, and the quote includes the line: How he avoided ...
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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 ...
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How to seal the connection between the combustion chamber and outer shell in this rocket engine model?

Here is rocket engine drawing. The combustion chamber made from copper and the outer shell from stainless steel. The coolant, either water or gasoline will be between (source: wonderhowto.com) With ...
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How often can liquid hydrogen engines be restarted?

A proposal for lunar development, LunarCOTS, relies on a reusable shuttle running on LH2 and LOX to work. It lands, is refueled on the lunar surface, and then takes off again. Presumably it could sit ...
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What is the MXP-351 storable bipropellant?

Masten Space Systems has a proprietary hypergolic bipropellant called MXP-351 intended for use in the XL-1 lunar lander. We seem to know the following information: Non-cryogenic, with storage life of ...
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14 votes
2 answers
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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?
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What is the spherical tank in this drawing of the BFS?

The big news in this article is the extremely large carbon-fiber fuel tank. However, the drawing in the article does not show it well. Instead what stands out like a sore thumb in the drawing is the ...
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Liquids Plumbing on board

When a cargo mission is flown toward the ISS, there are at least four different kinds of liquids that may need to be moved into/out of the station: Propellant for Zvezda's thrusters Water Wastewater ...
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4 votes
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Can kerolox or SRB soot particles grow too large too quickly; not accelerated in expanding exhaust leading to a loss of mass-specific impulse?

In this answer to Is methyl silane CH6Si ever considered as fuel in rocketry? I argue that there's no huge loss in mass-specific impulse (Isp) when producing sand (and by extension soot) in the ...
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Is HAN-water propellant "green" enough to ever be used in a cubesat?

I just read about the "green" propellant Hydroxylammonium nitrate writing this answer. It will be tested in the Green Propellant Infusion Mission (also see GPIM AF-M315E Propulsion System). Catalytic ...
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What are these thirteen purple grape-like things inside this tank?

I am not sure this is a view of the inside of a liquid propellant tank, and even if was, not sure if it belongs to a Falcon 9 per se. But there are places for fourteen round objects at the far end, ...
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Can we use liquid propellants in amateur rockets?

Is it possible and worth it to use liquid propellants like liquid oxygen and liquid hydrogen in amateur rockets? What are the other types of liquid fuel used? Moderator's Note: Remember discussion ...
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3 votes
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Limiting factors of liquid rocket engine thrust

What are the limitations for the 1st stage liquid fueled rocket engines that are currently in widespread use, what are the factors that limit their total thrust? Why can't you just inject more and ...
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16 votes
5 answers
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Can a solid first stage compete with a liquid fueled first stage?

The thing about solids is that they can have awe inspiring amounts of thrust compared to liquid engines, as you can see in this collection of boosters and thrust levels: Shuttle SRB - 2.8 Mlbs Ariane ...
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Why does the BE-4 use methane as fuel?

I understand the Mars ISRU reasoning for SpaceX's Raptor which is also going to be methalox based. But why would ULA, who is the prime customer for BE-4 besides Blue Origin itself, chose to support a ...
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19 votes
2 answers
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What was the reason to use different fuel for the Apollo Service Module propulsion system and reaction control system?

The Apollo Lunar Module LM used the same fuel/oxidizer combination (Aerozine 50 fuel / nitrogen tetroxide (N2O4) oxidizer) for both descent and ascent stage engines and reaction control system. This ...
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If LOX/LH2 were used in a fuel cell powering an ion engine could it provide a greater delta-v than with a conventional engine?

Question: If LOX/LH2 were used in a fuel cell powering an ion engine could it provide a greater delta-v than with a conventional engine? Conditions: Start in space in a stable heliocentric orbit (no ...
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Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios?

Question: Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios? Are there fundamental engineering ...
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Are ICBMs and orbital launchers similar enough to be co-developed today?

Russia has two types of hypergolic liquid fuel ICBMs deployed, UR-100N and R-36M2 Vojewoda and they are working on the big Sarmat. There's in this category also the Chinese DF-A5. (A list of ICBMs ...
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Do any rocket engines besides the F1 need/require baffles?

The F1 engine required baffles on the injector plate to control combustion instabilities so that it wouldn't blow itself up. Was that unique? Or do other engines also have baffles for the same reason? ...
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5 votes
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How much does launch costs have to come down to make chemical fuel deep space probes feasible?

Considering that NASA have been running short of plutonium for their RTGs, it makes sense to consider alternatives. For the inner solar system up to Jupiter, solar cells have been demonstrated on ...
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2 votes
1 answer
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Chamber pressure of a gas pressure fed liquid rocket motor

I am studying rocketry and am currently learning about pump fed vs gas pressure fed propulsion systems. Upon reading about gas pressure systems, I googled the formula to find the chamber pressure for ...
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14 votes
1 answer
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What is the advantage of using Helium over Nitrogen when used for pressurising LOx?

In this Twitter post of the plumbing line diagram(left half) by LauncherSpace, one can notice that Helium is used for pressurising LOx while Nitrogen is used for pressurising Kerosene. Why the ...
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10 votes
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why do under-expanded engines have less than ideal thrust?

I've been looking into rocket propulsion a bit and got stumped on something. I read that the thrust generated by an engine can be determined by the following: $$ F = \frac{w}{g}v_{e}+A_{e}(P_{e}-P_{a})...
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10 votes
1 answer
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Why is the Deep Space Industries Prospector 1 using water propellant instead of hydrazine?

A lot of satellites use hydrazine propellant but the Prospector 1 is using water. What are the benefits and drawbacks of that decision?
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8 votes
3 answers
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Why doesn't Rocket Lab use a solid stage?

I was just reading about the Scout, an all-solid rocket, and thought of Rocket Lab's Electron, which seems to have a similar mission of deploying small payloads to orbit. I understand the engines to ...
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Why can’t cryogenic propellants be storable, at least on the ground, via refrigeration?

Cryogenic fuels (liquid hydrogen, liquid methane)1 and oxidisers (liquid oxygen)2 are the rocket propellants of choice where raw performance is the overriding concern, due to the very high performance ...
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7 votes
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What challenges are there for more, smaller liquid fuel engines instead of one large?

Some questions popped up about difficulties of creating throttleable liquid fuel engines. I wonder why the obvious alternative isn't more common: multiple engines, from which only some will be lit; ...
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7 votes
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What is producing the orange-brown smoke in the exhaust of some North Korean missiles?

Accompanying a newsreader's report of North Korea's launch of a new long-range (claimed up to 10,000km) missile is footage of a launch in which the rocket produces clouds of orange/brown smoke. ...
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6 votes
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Which is the preferred mode of liquid rocket engine cutoff - fuel lean cutoff or fuel rich cutoff?

When a bi-propellant liquid rocket engine receives a command to shut down, will the fuel gets cut off first and then the oxidiser - a fuel lean cutoff? Will the oxidiser gets cut off first and then ...
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5 votes
1 answer
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Is N2O a practical monopropellant?

N2O has been worked with very early on in the 40s and now again is seeing a resurgence. Is this interest merited, disregarding its apparent non-toxicity, and how well does it perform in an engine/...
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5 votes
1 answer
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Is a fluorine/hydrogen engine feasible for use in space? [duplicate]

Fluorine is a bit more efficient chemically than oxygen. It has never been used as a launcher oxidizer because it and its exhaust products are so toxic. That's as much I've heard about it anyway. But, ...
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