Questions tagged [liquid-fuel]
Questions regarding rocket propellant in liquid form, the main type used for chemical rockets.
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How much more hardware is needed in a cross-fed CBC rocket than a non-cross-fed one?
Is it just a matter of adding a multi-in fuel manifold?
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3answers
750 views
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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1answer
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What kind of methane-fueled rocket engines exist?
I have heard of methane being a strong contender for Mars and beyond. Methane is a cryogenic fuel and is said to have a high specific impulse, and work with closed- and open-expander cycles. I have ...
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1answer
103 views
How much fuel/oxidizer was held in the piping of the Shuttle orbiter?
The space shuttle main engines were in the orbiter portion of the vehicle, but fed fuel (LH2) and oxidizer (LOX) from the external tank. Suppose the external tank is ejected before the LH2 and LOX ...
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1answer
145 views
Can Amateur Rocketeers use Liquid Nitrogen Dioxide as oxidizer?
I was reading similar question as mine here. But no one talked about Nitrogen Dioxide (NO2). Its boiling point is 21C. So easy to store. But how easy it is to handle compared to Hydrogen Peroxide or ...
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0answers
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LOX as annular heat sink
I'm thinking of my time spent working with cryostats. Liquid helium pot on the inside, and surrounded by a liquid nitrogen jacket. And the whole thing insulated with vacuum and superinsulation. (...
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1answer
78 views
How do pressure fed and pump fed systems compare at different scale of rockets
Rocket Design is all about optimising mass, within cost constraints while accepting a certain amount of risk. Both pressure fed and pump fed systems have their pros and cons, but how do they compare ...
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1answer
55 views
What differences exist between the pressurants and their associated systems between a pressure fed and pump fed liquid rocket engine
There is an apparent need to have pressurants in both pressure fed and pump fed systems. However, since pump fed systems can create the necessary pressure, they can work with less pressurants and ...
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1answer
81 views
What happens when LOX and H2 are injected into the combustion chamber of a rocket?
I can't seem to find an answer on this.
I thought that when oxygen and hydrogen get injected they collide and break bonds etc. to form water vapour which because of the pressure in the combustion ...
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79 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 ...
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0answers
35 views
What are some common exit pressures for liquid propellant engines?
Most engines are overexpanded at launch so that they reach peak efficiency at altitude. It’s easy to find values for thrust, specific impulse, expansion ratio, chamber pressure, etc, but I’m trying to ...
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1answer
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Can I able to use RP 1 and LOX in metal tin small size rockets? Is that possible? [closed]
I love rockets. Planning to build a tin rocket but not with water and air pressure. I would like to build a small metal tin rocket using fuel as RP 1 and oxidizer as LOX. I know this is too hazardous ...
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Would a liquid propellant fire in Mars' atmosphere cause charring?
If a ship carrying liquid propellant crashed on the surface of Mars, rupturing all tanks, I assume the propellant could ignite.
If the propellant did ignite might it leave indications of charring on ...
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2answers
129 views
Solid hydrogen hybrid motor engine for launch?
Would hydrogen unlike water in a solid state take less space or be more stable? How would a rocket work using a block of melting solid hydrogen instead of liquid hydrogen? Has and could any kind of ...
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3answers
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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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1answer
201 views
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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1answer
137 views
What liquids last the longest in space?
I am trying to find something that is somewhat stable as a liquid in space. What happens to various liquid elements and compounds in a vacuum? Is there a list or table of the effects of local space ...
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Why doesn't a regeneratively cooled engine crack due to differential expansion induced by thermal gradients?
A liquid rocket engine with regeneratively cooled chamber walls and nozzles would definitely be one among those components experiencing the steepest thermal gradients (Chamber wall inner - $3000 K$ ...
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2answers
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Why are LOx plumbing not insulated?(ref: Huzel and Huang)
In the book Modern Engineering for Design of Liquid Propellant Rocket Engines, the following excerpt appear in chapter 9 - Interconnecting Components and Mounts:
The liquid-oxygen lines were not ...
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2answers
174 views
Other than He and N as pressurizing gases
To pressurize the liquid propellant tanks Helium is most widely used and after that Nitrogen. Helium is quite costly and Nitrogen is economic but it messes with the O/F ratio of the engine (ref). So, ...
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97 views
How are the liquid propellant umbilical cord protected from the exhaust?
The launch pad umbilical cords supply propellant to the rocket, and will definitely have some remaining at the time of liftoff.
I remember the Saturn V footage wherein a heavy protection door slams ...
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1answer
1k views
Why is a purging process necessary for static firing test of liquid rocket engines?
In Chapter 7 of Modern Engineering for Design of Liquid propellant Rocket Engines by Huzel and Huang, mentions the following engine cut off procedure.
The cutoff sequence usually consists of
...
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37 views
Effect of the location of igniter in starting liquid rocket engine
What will be the effect of off axis igniter, say a Spark igniter has to be used along with a pintle? Will the igniter being off axis have any effect on engine start?
Also, will an off-center igniter ...
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1answer
296 views
Why are 22N and 440N liquid engines quite common?
One can often spot that liquid apogee engines are 440 N and attitude control systems are 22 N.
Is there a reason why the thrusts are proportional? If the engines are scaled for reducing development ...
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2answers
207 views
Challenges of using propyne (aka methylacetylene) as rocket fuel
Propyne is a light hydrocarbon which packs quite a lot of energy in a triple carbon bound. It poses no significant health or explosion hazard by itself, and some European studies have found it to be a ...
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2answers
127 views
Liquid propellant stored as solid
Some propellants have wildly different melting points. The most extreme case is the theoretically fantastic (and nightmarish in practice) Fluorine-Lithium-Hydrogen tripropellant, with liquid hydrogen ...
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2answers
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How does SpaceX plan to deal with boiloff on the trip to Mars?
Both BFR booster and BFS are to run on Raptor engines, fueled with liquid methane and liquid oxygen - cryofuels.
The trip to Mars will take at least a couple months, and BFS requires fuel for powered ...
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1answer
933 views
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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117 views
Do rocket labs store propellants at higher pressure than the other rockets?
It is known that the Rutherford engines run on an electric pump-fed cycle. There must be a trade-off between the tank pressure of the electron rocket and battery capacity, for batteries are dead ...
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How to overcome the challenge of igniting kerosene using spark plugs?
Discussions in this question and its answer, concerning the use of spark plug ignition for Kero/GOx system outlines the energy limitations of spark plugs to ignite the mixture.
But Ignition Transient ...
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1answer
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Does kerosene get ignited by a spark plug? [duplicate]
Are spark plugs used in kero-LOx engine(say J1 engines)? If so, then there are two major issues when using spark plug to ignite kerosene.
Wetting of the spark plug causes spark to be smaller and the ...
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1answer
186 views
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 ...
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1answer
92 views
What parameters of an rocket engine determines whether it is fit for any more static hot fire test?
Typically engines built are repeatedly hot fired to analyses their performance.
In between tests, what are the review that the engine undergoes? How is an engine gauged suitable for a hot fire ...
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3answers
1k views
Impact of tidal forces to a liquid in a half-full tank
The german Wikipedia article about tidal forces contains a sentence which mentions, that tidal forces have an impact to an half-full fuel tank:
Wo keine mechanisch feste Verbindung besteht, können ...
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1answer
297 views
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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1answer
134 views
What is advantage of independent pumps vs common pump in clustered configuration?
The images of the engine clustering in the Rocket Labs's Electron rocket gives an indication that there are independent drive pumps for individual engines; I am not sure of it. I am not aware of the ...
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Pressure queries on turbopumps
In the turbopump used in liquid rockets, the stagnation pressure rise is definite. But then the question comes:
Whether static pressure rises or dynamic pressure rises or both rises? If both rises ...
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1answer
129 views
What is the surrogate liquid for LOx during the preliminary testing of injectors?
Before transitioning to the LOx tests during any new injector development, water is typically used for calculating flow rates, pressure loss, etc.
But testing with water cannot qualify as a suitable ...
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1answer
720 views
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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1answer
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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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5answers
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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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1answer
78 views
How to calculate mass of fuel for Venus Orbiter
I'm working on a hypothetical constellation of orbiters at Venus for a school project, and I am currently trying to figure out how much fuel I need in the transfer stage. I have already calculated ...
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2answers
296 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 ...
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1answer
96 views
If anything, what can cause a rocket engine to flame out prematurely?
I would assume that dropping flow rates or a drop in chamber pressure would cause the engine to stop thrusting, but I am unaware as to what specifically these conditions might be.
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Trade-offs in developing larger engines vs using more smaller engines
Looking to explore the inverse point of this question:
What challenges are there for more, smaller liquid fuel engines instead of one large?
As stated in the answer to the above question, fewer, ...
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1answer
697 views
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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Why aren't injector pumps used in rockets?
Is there something that makes injectors unsuitable as oxidizer pumps? Seems to me that rockets would benefit significantly from a pump with no moving parts that runs off its own exhaust.
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1answer
360 views
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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2answers
494 views
Is there a chemical propellant combination with Isp between Methalox and Hydrolox?
Methalox rocket engines (Liquid Methane and Liquid Oxygen) have theoretical specific impulse in the high 300's.
Hydrolox rocket engines (Liquid Hydrogen and Liquid Oxygen) have theoretical specific ...
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4answers
350 views
Modern ambient temperature rocket fuel?
This question is in regard to rocket propellants that are liquid at room temperature & pressure (not solid fuel, and not liquid hydrogen liquid oxygen, both of which would be gasses at STP).
It'...
