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Questions tagged [pressure]

Pressure is the force applied perpendicular to the surface of an object per unit area over which that force is distributed.

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Is a dome really the most efficient way to contain gas in a vacuum?

It's pretty common to see some artist or even engineer come up with an idea of a lunar or Martian colony with a big ol' glass dome up top. And we seem to have been doing this since the 60's. But ...
Thesaurus Rex's user avatar
4 votes
1 answer
78 views

Pressure Term in Rocket Thrust Equation

In the rocket thrust equation, as well as the thrust due to the mass flow rate of the exiting propellant, there is also an additional pressure term included. However I have noticed that this term is ...
G11's user avatar
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Is the turbopump outlet pressure higher or lower than the combustion chamber pressure? [duplicate]

I always thought turbopump outlet pressure was higher, but when I asked chatGPT, it said the chamber pressure is higher in open cycle rocket engines. Now I am confused because how would that work if ...
Anish Kommireddy's user avatar
2 votes
1 answer
254 views

How to design a Blowdown or Pressure Regulated pressurization system for a spacecraft?

I am trying to develop a simple tool to size a pressurization system for a spacecraft using either a blowdown pressurization system (BD) or a pressure regulated (PR) pressurization system. Though I ...
Mario Pastore's user avatar
18 votes
4 answers
4k views

What stages of distress occur to a person when there is a small hull breach in space?

I'm working on a short sci-fi game and I'm curious about how the effects of a hull breach in a confined area play out. For perspective, let's say a very confined space of 100 cubic feet of normal, ...
HAL 9000's user avatar
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Aerostats in the outer solar system

Having read a lot lately about some preliminary studies of aerostat options on Venus and Earth (Semirigid gas bags filled with N2/O2 to allow for a dual breathable/lifting gas - sorry no source on ...
AnarchoEngineer's user avatar
6 votes
1 answer
1k views

Upper limit of human comfort in higher atmospheric pressures?

At what atmospheric pressure, assuming an earth-like atmospheric composition, do humans start to feel uncomfortable? I am not asking for the max survivable pressure, but the point where long term ...
GoingFTL's user avatar
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Can propellant tanks in a pressure-feed rocket be pressurized by burning the propellant inside those same tanks? Recipe for Ka-BOOM?

Pressure-fed liquid fuel rocket engines use pressurized propellant tanks to deliver propellant to the combustion chamber, rather than pumps. This eliminates the mass, cost and complexity of the gas ...
Woody's user avatar
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7 votes
3 answers
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Can we dig for air pressure on Mars?

Digging 8km under the lowest point on Mars will get us Mount Everest conditions for air pressure. I was thinking of two ways of doing said title: Nuclear powered bulldozers working around the clock ...
David Ong's user avatar
1 vote
1 answer
233 views

How to find the average ambient pressure during rocket ascent?

I am trying to find the average ambient pressure that my rocket will flight through during its ascent to then determine the most optimum conditions in my combustion chamber and nozzle. I have ...
stanisverylow's user avatar
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Analytical representations for thrust in underexpanded flow (P_e>P_a) [duplicate]

I am familiar with the ideal thrust equation: $F=\dot{m}U_e +(P_e-P_a)A_e$ When $P_a$ is greater than $P_e$, you have thrust losses, and the equation accounts for that. When $P_a=P_e$, you achieve ...
alexmesa's user avatar
10 votes
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When staying indoors, can missing gravity be replaced with blowing air?

As I was watching Ad Astra (Great movie, but where does the gravity come from?), I had the idea that in a building or closed vehicle in a low gravity location, maybe air pressure could be used to ...
Antti Rytsölä's user avatar
1 vote
1 answer
57 views

Would pressure oscillations at the inlet of a liquid engine turbo-pump subside at the outlet, or would they get amplified?

Would pressure oscillations at the inlet of a liquid engine turbo-pump subside at the outlet, or would they get amplified? What are the factors that decides the change in the amplitude of pressure ...
Jithin's user avatar
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1 answer
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How is a desired chamber pressure achieved in a liquid rocket engine

Before everyone responds that this has been asked before, I have read through every relevant post I could find here and believe my question has not been clearly covered. I also understand that "...
rockets_go_boom's user avatar
24 votes
2 answers
6k views

Why aren't spacecraft and spacesuits pressurised to 2.5 psi (17 kPa) of pure oxygen?

Today 1 atm (101.3 kPa, 14.7 psi) with sea level composition is most commonly used on spacecraft to avoid fire hazards like in Apollo 1 (not that it would have helped the Apollo 1 crew as they couldn'...
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4 votes
3 answers
310 views

How to read this Cassini Main Engine Operating Box (oxidizer vs fuel tank pressures)?

The extremely cool NASA JPL video Triumph at Saturn (Part I) is really worth a watch and/or listen. At about 34:32 it covers the period just before SOI (Saturn ...
uhoh's user avatar
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What keeps the pressure stable inside the ISS?

I'm doing research on life support systems for the design of a Martian scientific base, and I'm having trouble finding information about the specifics racks that keep pressure stable inside the ISS. I ...
Agus Gamalerio's user avatar
4 votes
1 answer
136 views

What is the planned Nuwa city atmosphere?

Nuwa is a proposal for a large-scale permanent Martian settlement. What is the planned atmospheric composition of Nuwa city's air? Will it be 15psi Oxygen/nitrogen, and trace gases or low partial ...
L5Rick's user avatar
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What equation is being used- chamber pressure v.s. mass flow rate? (Cold-gas thruster)

I am doing a project on cold gas thrusters and have seen a couple of graphs relating chamber pressure against mass flow rate. I can't seem to find the equation that relates these two parameters to ...
spacegirl98's user avatar
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Pressurant gas line design considerations

I am trying to understand the constraints on pressurant gas line sizes and lengths. For a static volume, the lines can be small in diameter because there is no significant flow velocity and therefore ...
Vulinhlanhla's user avatar
5 votes
1 answer
504 views

How is the pressure within the gas generator determined?

The fact that pressure fed engines need their tanks to be at an even higher pressure has always confused me a little, but it's got me thinking; does the same logic apply to gas generator engines. If ...
R. Hall's user avatar
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4 votes
1 answer
197 views

Is there a relation between combustion instabilities and chamber pressure?

Is there a relation between the combustion chamber pressure, and either an increase or decrease in both high and/or low frequency combustion instabilities. If so, how has this influenced engine design,...
R. Hall's user avatar
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3 votes
0 answers
280 views

What is the inlet and outlet pressure of Merlin LOX/RP-1 turbopump?

I got the inlet and outlet pressure of Saturn V engines turbopumps here, but I couldn't find the turbopump pressure of the Merlin engine of Falcon 9.
Hello Humans's user avatar
2 votes
2 answers
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Pressure levels inside rocket liquid oxygen tanks?

What is the pressure levels inside rocket liquid oxygen tanks, at launch time? The question is for the minimum and maximum (known) levels of pressure inside such tanks. I am asking for any rocket ...
Joe Jobs's user avatar
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1 vote
1 answer
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How does one determine the optimal CH4:O2 ratio in a methane-LOX rocket engine?

The SpaceX Raptor uses a 78:22 O2:CH4 ratio. It also has combustion chamber pressures higher than any other rocket engine ever built. My questions are: What's the math / chemistry that determines ...
Ron Peacetree's user avatar
10 votes
3 answers
4k views

If there's a hole in Zvezda module, why didn't all the air onboard immediately escape into space?

The ISS is leaking through a hole in the Zvezda module that still hasn't been found. However, as with all pressurized chambers, shouldn't all air instantly run out through the hole into the vacuum of ...
Greenhorn's user avatar
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7 votes
2 answers
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Why does the Falcon 9 use turbopumps as well as helium pressurisation system?

Falcon 9 first stage use turbopumps as well as helium pressurisation system. Isn't the turbopumps enough to pump in the propellants to the combustion chamber?
Ashvin's user avatar
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1 vote
0 answers
194 views

what is the ISP loss associated with pressure fed engines

Numerically, what is the approximate loss of overall system specific impulse associated with pressure-fed rocket engines, not only as a result of the low chamber pressure but also of the additional ...
R. Hall's user avatar
  • 822
10 votes
2 answers
723 views

Do lower pressure pressure-fed rockets get more Delta-V?

I was playing around with the math for getting a pressure-fed rocket to orbit and came across something that I haven't seen addressed anywhere. In a pressure-fed rocket, the chamber pressure of the ...
Orion DeYoe's user avatar
5 votes
0 answers
193 views

Low-pressure pump-fed rocket engine?

I saw the above suggested in LEO on the Cheap. In P.130 it says: A compromise between high-performance/lightweight pump-fed vehicle designs and cost-optimized pressure-fed vehicles with heavier ...
Abdullah is not an Amalekite's user avatar
5 votes
1 answer
1k views

Can exit pressure of nozzle be less than atmospheric pressure?

This is kinda dumb question .I got 5psi pressure at outlet of the nozzle from open motor software. Is that possible because its less than atmospheric pressure 14.7 psi? Am i missing out something?
Auberron's user avatar
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3 votes
0 answers
265 views

Merlin combustion chamber pressure

What is the combustion chamber pressure for Merlin? I mean the average and the maximum The Raptor engine was tested with a maximum 330 bar. I would like to compare them
Joe Jobs's user avatar
  • 2,650
2 votes
0 answers
216 views

Design of propellant tanks of a rocket [duplicate]

I understand that the propellants (e.g. LOX & LH2) are stored in a rocket tank which is pressurized by Helium or a neutral gas, so as to push the propellants towards the tank outlet, to the turbo-...
Niranjan's user avatar
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10 votes
1 answer
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why do under-expanded engines have less than ideal thrust?

I've been looking into rocket propulsion a bit and got stumped on something. I read that the thrust generated by an engine can be determined by the following: $$ F = \frac{w}{g}v_{e}+A_{e}(P_{e}-P_{a})...
Ben Woodman's user avatar
3 votes
0 answers
230 views

How strong is the Starship bottom bulkhead?

I am wondering how much of a role does the pressurization of the propelant tanks play in making them withstand the engine thrust. What I am getting at is how much would the pressure offset or balance ...
PunchyRascal's user avatar
2 votes
1 answer
1k views

Nozzle Exit Pressure Too High?

I've been doing some simple rocket science for fun, and I wanted to calculate the specifications of the Lunar Module Descent Engine (LMDE). The LMDE uses Aerozine-50 (UDMH) and Dinitrogen Tetroxide($...
Star Man's user avatar
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Rocket Combustion

How is the chamber pressure is arrived at for a given combustion temperature and mixture ratio ? Based on the mixture ratio, the value of gamma and temperature can be found out, using chemical ...
Nikhil's user avatar
  • 11
6 votes
1 answer
488 views

What effects did the different air pressure and air composition in certain spacecraft have on astronauts?

The Mercury and Gemini spacecraft, and in space the Apollo spacecraft, didn't pressurize their cockpits to 1 atm with Earth-like atmospheric composition; instead, they used pure oxygen at much lower ...
user avatar
6 votes
2 answers
2k views

Does chamber pressure have the same impact on ISP for different types of engines?

From this answer I understand that higher chamber pressure means higher ISP - but is this always the case for similar engines? For example: I noticed that a lot of upper-stage engines have pretty low ...
irakliy's user avatar
  • 615
0 votes
0 answers
64 views

Relationship between scaling up rocket, adding more engines and pressure inside tanks, feedlines

So can anybody say, what is relationship between scaling up rocket ( more payload to orbit ) adding more engines and pressure inside rocket tanks, feedlines. What is standard pressure inside F9R 1st ...
bigbang's user avatar
  • 151
3 votes
2 answers
427 views

What was pressure and temperature of LM oxygen tanks?

After analysing comments in related question How cryogenic oxygen was heated up for CM cabin repressurization? It appears that LM had oxygen stored as either gas or supercritical fluid but not at ...
Sergiy Lenzion's user avatar
1 vote
2 answers
269 views

Can we create a vacuum inside an EVA suit when the outside is pressurized, will it implode?

EVA suits are specially designed spacecrafts for astronauts during spacewalks. I can say for sure, it can handle the following cases of pressurization of the system: Pressurized inside, but vacuum ...
Vishnu's user avatar
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4 votes
1 answer
148 views

Is the risk of depressurization greater in atmosphere than in orbit?

This question inspired by a short Twitter exchange with @thehighfrontier about clothing for Spaceship Two passengers. Crews of particularly high-flying aircraft wear full pressure suits. So do ...
Erin Anne's user avatar
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1 vote
0 answers
54 views

How would a hybrid motor N2O propellant tank control pressure?

Cryogenic engine prop tanks vent in order to control tank pressure. Thermal energy that (inevitably) gets conducted into a cryo tank raises the propellant enthalpy and so the pressure of the critical ...
Superfort's user avatar
0 votes
1 answer
128 views

Could LNG fuel be used to pressure feed itself into combustion chamber?

In pressure fed cycle a high pressure gas tank contents are exhausted into the fuel and oxidizer tanks to essentially push them into the combustion chamber. Could a portion of the fuel from an LNG ...
Krzysztof Broda's user avatar
2 votes
1 answer
586 views

Chamber pressure of a gas pressure fed liquid rocket motor

I am studying rocketry and am currently learning about pump fed vs gas pressure fed propulsion systems. Upon reading about gas pressure systems, I googled the formula to find the chamber pressure for ...
Dylan Meiners's user avatar
5 votes
2 answers
393 views

Oxidizer Line Pressure of DIY Hybrid Rocket Engine Limits Thrust?

So I’ve seen engines like these which use gaseous oxygen as an oxidizer and then a solid tube as a fuel. But do these types of hybrid engines have any possibility of creating a useful amount of thrust?...
Jacob G's user avatar
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4 votes
1 answer
302 views

Sulphur Hexafluoride atmosphere for Ceres?

So, I have read that the escape velocity of Ceres is 514 m/s, and orbital velocity(for a low orbit) is 360 m/s... Now, the RMS(Root Mean Square) velocity of Sulphur Hexafluoride at 72 $^o$F (23 $^o$C,...
mzs.112000's user avatar
0 votes
1 answer
337 views

Ambient pressure for vaccum nozzle design

How do I find out the ambient pressure for designing a vaccum rocket engine? I am using the propellant combustion charts from the braeunig website. But I cannot figure out the ambient pressure for ...
user167195's user avatar
2 votes
2 answers
298 views

Could an Igloo work on Mars?

Could ice make a good habitat like an igloo for colonists or as cold storage for fuel? Could the cavern be sealed and then carbon dioxide melted to create pressure inside the cavern to grow plants or ...
Muze's user avatar
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