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Questions tagged [hydrogen]

Questions about the element hydrogen, typically related to its use as rocket fuel.

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4answers
4k views

Why does the Falcon 9 use RP-1/LOx and not LH2/LOx?

Why does SpaceX use RP-1 in the first and second stages of their rockets? In my view at least the second stage could use hydrogen as it currently is not being reused. I am aware that you have higher ...
6
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2answers
99 views

How do you calculate what percent of hydrogen combustion is turned into heat vs pressure?

As a high school calculus and physics student interested in aerospace engineering, I was trying to understand the basics of how a rocket works and couldn’t find an equation or any analysis online on ...
2
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1answer
253 views

Manufacturing H2 and O2 rocket fuel components?

I'm curious as to the typical manufacturing (or gathering) methodology of H2 and O2 used in modern rockets for fuel and oxidizer. It would seem that the most straightforward process would seem to be ...
6
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1answer
741 views

Why does the SABRE engine have ramjets?

The SABRE engine is designed to power the Skylon SSTO vehicle. It reduces the amount of oxygen that needs to be carried by cooling and compressing air in the early part of the flight. More hydrogen is ...
3
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3answers
315 views

Could a terrestrial planet with a hydrogen atmosphere be habitable?

Many exoplanets, even small ones, have densities so low that it indicates that they have hydrogen atmospheres. Is a hydrogen gas atmosphere of a terrestrial planet somehow detrimental to biology as we ...
2
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1answer
345 views

Better understanding of the “Rivers of metallic hydrogen” in the atmosphere of Jupiter?

Between 03:00 and 05:00 in the BBC's radio program Giant hurricanes at Jupiter’s poles, BBC's science correspondent Jonathan ...
6
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1answer
1k views

Would (theoretically) metastable solid metallic hydrogen even need an oxidizer?

In this answer there is discussion of some research on the potential, future use of a solid metallic hydrogen phase that would be metastable at ambient pressure as a rocket propellant. The work is ...
1
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2answers
392 views

Has (theoretically) metastable metallic hydrogen been considered for use as a propellant?

I'll just point to the following two questions and their associated answers for background: For the recently reported production (January 2017) of metallic hydrogen in the laboratory - what is the ...
16
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5answers
918 views

Is atmospheric skimming for propellant feasible?

A recent comment in a discussion of satellite refueling mentioned the possiblity of a spacecraft dipping into the atmosphere from LEO to obtain oxygen. Similarly, the science fiction RPG Traveller ...
21
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1answer
903 views

What was the result of the propellant predictions in the last chapter of “Ignition!”?

In John D. Clarke's Ignition! (1972), the author spends the last chapter making predictions about the future of liquid rocket propellants. I thought these were very interesting, but I realize the book ...
10
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1answer
169 views

Has solidifying liquid propellant been considered for space exploration?

Liquid hydrogen is $0.071 g/cm^3$ Solid hydrogen is $0.086 g/cm^3$ Since denser fuel is desirable, has solid hydrogen been considered for use in space exploration? I suspect the very low ...
6
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2answers
605 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 ...
4
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2answers
896 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 ...
0
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2answers
308 views

Have reliable, restartable LH2/LOX engines ever existed? - ever used? [duplicate]

I just wrote the following paragraph as an edit to this answer: Using LH2 for regular burns to maintain ISS altitude would require a whole new set of engines that may not yet exist anywhere. While ...
9
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1answer
499 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? ...
12
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1answer
10k views

Why is TEA-TEB chemical ignition used instead of spark ignition?

Both the Saturn V and the Falcon 9 use TEA-TEB to ignite their kerosene-fueled engines. TEA-TEB is pyrophoric, igniting spontaneously on contact with air. This poses handling issues; it must be stored ...
4
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1answer
245 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 ...
6
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3answers
608 views

Who built the sparklers used by the Shuttle program during launch?

The Shuttle main engines used LH2 and LOX, and used sparklers to burn off the hydrogen that would be exhausted, unburned, during engine startup. (They pre-chill the engine components so that they are ...
1
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1answer
83 views

Would electrically charged hydrogen tanks lower leakage?

It is a (maybe marginal) problem for long duration space flights that hydrogen fuel leaks through its containing tank. I suppose it is because a hydrogen atom some of the time loses its electron and a ...
2
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0answers
61 views

Would a low pressure container lower hydrogen leakage in space?

Hydrogen, for rocket fuel, tends to leak even through metal containers. Launchers carry hydrogen cooled to liquid in order to save storage space for aerodynamical reasons, but that is unnecessary in ...
14
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1answer
766 views

How do they conduct electrolysis in zero gravity?

I'm building an electrolysis cell myself, and got to wondering. On Earth, there is a significant force pushing bubbles of hydrogen and oxygen upward, so your electrodes still contact mainly water. ...
8
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1answer
219 views

Is the Hybrid sulfur cycle a good way of making hydrogen and oxygen on Venus?

Assuming we collect Sulfuric acid from Venus clouds using some sort of airship, what would be the best way of turning this into hydrogen and oxygen? I came across something called the Hybrid sulfur ...
4
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2answers
261 views

Are cryo tanks heavier than normal tanks (on a per surface area basis)?

From my related question, it turns out cryo tanks are not double-walled for insulation purposes. So now I will continue along a similar line and ask, aren't cryo tanks heavier than normal tanks on a ...
6
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2answers
749 views

A cryo tank within another cryo tank…is it a sound engineering concept?

Here's the idea: A large spherical LH2 tank is placed inside a spherical LOX tank. The reason I thought of this is so the inner tank doesn't need to be insulated. It doesn't need to be a double-...
3
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2answers
176 views

Fuelling LH2/LOX conectors for Rockets - is it easy to manually attach to the intake nozzles?

I noticed that many rockets come out of the assembly building already with their fuelling umbilicals attached (I mean, with the entire umbilical tower - like Saturn 5, Ariane 5). Once in the launchpad,...
6
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2answers
227 views

Technology for LH2 & LOX umbilicals for rockets

Does someone knows why H-IIB rocket can stay fuelled on launchpad for many minutes, just venting excess gaseous H2 and O2, while Ariane 5 must be connected to umbilicals almost to the very last moment ...
7
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1answer
1k views

How much does a hydrogen tank weigh compared to the hydrogen in it?

For the kinds of tanks used in upper stages, what is the ratio of the weight of the tank to the weight of the hydrogen? Are larger tanks more efficient? This is for considering transport of hydrogen ...
2
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2answers
290 views

Benefits of hydrogen cannon for first stage launch at sea level or 20,000 feet

I found three videos (2009 Google Tech Talk, 2011 International Mars Society Convention, 2011 Quicklaunch Inc.) from Dr. John Hunter about using a hydrogen gas cannon to launch payloads into space (or ...
18
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3answers
5k views

Can we use interstellar hydrogen as a fuel for interstellar travel?

From my understanding, space is not entirely empty. Infact, between the voids of space are molecules or maybe individual atoms of hydrogen just floating around. I understand that gathering massive ...
4
votes
1answer
426 views

Can a planet or other large body be a superconductor?

From Wikipedia on superconductivity of metallic hydrogen: In 1968, Neil Ashcroft put forward that metallic hydrogen may be a superconductor, up to room temperature (~290 K), far higher than any ...
14
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1answer
2k views

Why not use Sparklers on Delta-4 Heavy launches to burn off the hydrogen?

With three CBC (Common Booster Core) modules firing their RS-68A engines simultaneously, a Delta 4 Heavy launch is an impressive sight. The RS-68 is a LOX/LH2 engine. As part of the launch sequence, ...