Stack Exchange Network

Stack Exchange network consists of 175 Q&A communities including Stack Overflow, the largest, most trusted online community for developers to learn, share their knowledge, and build their careers.

Visit Stack Exchange

Questions tagged [liquid-fuel]

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

20
votes
3answers
4k views

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 ...
18
votes
3answers
4k views

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 ...
17
votes
1answer
718 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 ...
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 ...
14
votes
1answer
932 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 ...
14
votes
4answers
2k views

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 ...
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 ...
12
votes
4answers
11k views

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. ...
12
votes
1answer
2k views

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
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?
11
votes
2answers
2k views

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 ...
11
votes
1answer
606 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? ...
11
votes
2answers
439 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 ...
11
votes
2answers
687 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 ...
11
votes
1answer
268 views

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 ...
10
votes
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 "...
10
votes
1answer
793 views

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?
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 ...
9
votes
1answer
5k views

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 ...
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 ...
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 ...
8
votes
2answers
775 views

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 ...
8
votes
3answers
890 views

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
votes
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 ...
7
votes
3answers
960 views

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 ...
7
votes
2answers
498 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
votes
2answers
631 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 ...
6
votes
2answers
3k views

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 ...
6
votes
1answer
295 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 ...
6
votes
2answers
2k views

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 ...
6
votes
2answers
670 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
votes
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 ...
6
votes
3answers
4k views

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 ...
6
votes
0answers
172 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, ...
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.
5
votes
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 ...
5
votes
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 ...
5
votes
2answers
2k views

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. ...
5
votes
1answer
555 views

How does a gas generator engine begin ignition?

I am designing a liquid fueled amateur rocket with my brother, and settled on a gas generator engine. We understand the concept and process, however we are still confused on how the engine is ...
5
votes
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 ...
5
votes
3answers
345 views

Is there a demand for large liquid engines (> 5 MN)?

In other words, why was the F1 rocket engine programme stopped? Is there a sense that solid motors can take care of high thrust cases in a better way? Or is it an unfortunate fallout of the end of the ...
5
votes
1answer
295 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 ...
5
votes
1answer
359 views

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, ...
5
votes
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 ...
4
votes
2answers
909 views

Platinum Colloid in Liquid Hydrogen fuel to increase fuel efficiency

In certain chemical reactions, catalysts can be used to decrease the activation energy of those reactions. For example, platinum is a catalyst for hydrogen/oxygen reactions, so, therefore, the ...
4
votes
1answer
683 views

Is it correct to say that a LH2/LOX rocket uses water as propellant?

The title more or less sums it up. A rocket engine works pretty much by combining fuel and oxidizer, and expelling some propellant resulting in foward motion as described by Newton's third law of ...
4
votes
1answer
2k views

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 With either pressurised water or ...
4
votes
1answer
291 views

Liquid Helium (4.2K) sealed, then raised to sub-LOX temperature (~70K) - what is the new pressure?

In this question there is discussion of the large differences in temperature between liquid helium-4, subcooled liquid oxygen (sub-LOX) and cold kerosene (RP-1). Approximate temperatures are 4.2K, ~...
4
votes
1answer
257 views

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 ...
4
votes
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 ...