Questions tagged [liquid-fuel]

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

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24
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1answer
4k views

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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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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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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Do liquid propellant rocket engines experience thrust oscillation?

I know SRBs have a quite bit of thrust oscillation, and it's pretty much part and parcel of burning solid propellant. Do liquid-propellant engines experience something similar albeit at a much smaller ...
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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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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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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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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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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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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 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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Why don't rockets drive the turbopump from the combustion chamber?

As I understand it, liquid-fueled rockets typically burn some amount of their fuel in a separate low-pressure combustion chamber, and then use the combustion products produced to drive the turbopump. ...
13
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173 views

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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The principle behind regenerative cooling?

In regenerative cooling the fuel is passed around the nozzle before being pumped into the combustion chamber right? I don't really see how this affects cooling itself, since the heat captured around ...
12
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778 views

What is the ortho/para issue with LH2 as a fuel?

I remember reading somewhere that a catalyst was used to change the ratio of ortho- vs para-hydrogen before it is loaded as LH2 propellant on a rocket. What is this exactly, and why is it necessary? ...
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710 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 ...
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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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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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What is the density of supercooled LOX at −206 °C, as SpaceX uses it

I want to calculate the size in cubic meters of Starship's propellant tanks. The only figures for LOX I can find are at −183 °C. 1141.7 kg/m³ at −183 °C. Could somebody please calculate it at −206 °C,...
11
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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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6answers
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Is it possible to use gases instead of liquids as fuel in a rocket engine?

Im reading about rocket engines and I have a question about is it possible to use fuels in the form of gases than a liquid in a rocket engine?
10
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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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How are fuel/hydraulics pipes coupled in spacecraft?

How are pipes coupled in spacecraft? I found Shape memory alloy pipe couplings (SCoup, see image taken from link) are sometimes used. -Is this still the case and in what quantity are they used? -...
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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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738 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 ...
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Why can't cryogenic oxygen and cryogenic kerosene be “stored” together?

This question, to my knowledge, is only applicable to Rocket Lab's Electron, pressure-fed engines that use non-hypergolic fuels, and other engine cycles that don't use a fuel/oxygen-rich preburner. My ...
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2answers
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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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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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What's so hard about creating hydrazine?

I've read an article about EU lifting sanctions against Russia related to rocket fuel components. As far as I understand (correct me, if I'm wrong), Russia can now continue to export rocket fuel ...
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1answer
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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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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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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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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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2answers
289 views

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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898 views

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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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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225 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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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 ...
7
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1answer
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Do mixture ratio always need to be constant throughout the flight?

What factors can change the mixture ratio of propellant? I think they can be changed to control the thrust of a rocket.Stay safe. EDIT:What about considering only one stage? Do they change or can they ...
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Alternator/generator on launcher engines?

In Kerbal Space Program, most liquid fueled engines include a generator which provides electricity to systems on the rocket, keeping the batteries topped up while on ascent. Do any real rockets (...
7
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2answers
576 views

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; ...
7
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1answer
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Why is RP-1 dyed red?

I was interested to learn that RP-1 is at least sometimes dyed to a red color. What is the reason for doing this / what benefit does it give compared to leaving it the usual hydrocarbon clear-to-...
7
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1answer
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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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Autogenous pressurization with sub-cooled propellant

In his IAC 2016 talk, Elon Musk said (at 28m 4s in the video) that the ITS booster tanks would use autogenous pressurization. This means there is gaseous oxygen resp. methane in the tank. To stay ...
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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, ...
6
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1answer
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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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775 views

Why does the BE-3 use hydrogen as fuel?

We've covered why the BE-4 uses methane as fuel; what I want to know is, why did Blue Origin go with hydrogen for the BE-3? Liquid hydrogen is notoriously hard to work with; it seems like an odd ...
6
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2answers
929 views

Why were the Titan II's Flames Clear?

I've seen multiple sources attribute the clear flames to the use of hypergolic fuels for propulsion, but I have been unable to find any explanation for why hypergolic fuels burn clearly. (Image ...
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1answer
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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 ...
6
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1answer
137 views

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 ...