Questions tagged [liquid-fuel]
Questions regarding rocket propellant in liquid form, the main type used for chemical rockets.
5
votes
1answer
136 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 ...
2
votes
0answers
53 views
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. (...
4
votes
1answer
76 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 ...
1
vote
1answer
49 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 ...
2
votes
1answer
79 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 ...
2
votes
0answers
77 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 ...
2
votes
0answers
34 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 ...
1
vote
1answer
91 views
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 ...
1
vote
0answers
52 views
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 ...
2
votes
2answers
123 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 ...
14
votes
3answers
4k views
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 ...
5
votes
1answer
193 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 ...
1
vote
1answer
136 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 ...
4
votes
0answers
52 views
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 - $3000 K$ ...
2
votes
2answers
139 views
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 ...
2
votes
2answers
151 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, ...
1
vote
0answers
85 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 ...
9
votes
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
...
2
votes
0answers
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 ...
6
votes
1answer
285 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 ...
0
votes
2answers
191 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 ...
3
votes
2answers
125 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 ...
11
votes
2answers
424 views
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 ...
14
votes
1answer
920 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 ...
3
votes
0answers
116 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 ...
2
votes
0answers
58 views
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 ...
1
vote
1answer
131 views
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 ...
4
votes
1answer
175 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 ...
6
votes
1answer
91 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 ...
8
votes
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 ...
5
votes
1answer
282 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 ...
3
votes
1answer
128 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 ...
0
votes
0answers
27 views
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 ...
3
votes
1answer
125 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 ...
17
votes
1answer
698 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 ...
8
votes
1answer
1k views
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 ...
13
votes
5answers
1k views
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 ...
2
votes
1answer
75 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 ...
5
votes
2answers
238 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 ...
1
vote
1answer
94 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.
6
votes
0answers
168 views
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, ...
2
votes
1answer
650 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/...
6
votes
0answers
138 views
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.
1
vote
1answer
334 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 ...
1
vote
2answers
461 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 ...
3
votes
4answers
334 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'...
1
vote
1answer
111 views
An program that automatically generates a rocket guidance system?
This is for a liquid propelled rocket that launches from earth. It could also perhaps be used for orbital maneuvers and landing on the Moon (not mars or earth).
The inputs for such a program would ...
3
votes
0answers
51 views
How do current reusable boosters create fuel pressure for retro-burn? [duplicate]
For the SpaceX launches of the Falcon9 and Falcon Heavy, and also Blue Origin launch vehicles, the booster stage lands with a controlled decent and firing of main engines for retro-thrust.
During ...
3
votes
0answers
121 views
Does LOx stay as liquid when entering combustion chamber?
Given the heat from combustion and increased temperature, would the LOx still be in liquid form after emanating from the injector? Or will it instantly transform into gas?
Are injectors cooled using ...
12
votes
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?
