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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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 ...
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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 "...
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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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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 ...
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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 ...
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4 votes
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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 ...
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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 ...
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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 ...
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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 ...
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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,...
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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.
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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 ...
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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 ...
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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 ...
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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?
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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 ...
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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 ...
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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 ...
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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?
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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
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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-...
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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})...
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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 ...
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2 votes
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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($...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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2 votes
1 answer
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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 ...
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5 votes
2 answers
303 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?...
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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,...
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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 ...
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2 votes
2 answers
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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 ...
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How does temperature affect a solar sail?

Is there an ideal temperature which solar sail material operates at? Does a colder reflective surface create more thrust? Related: How will JWST manage solar pressure effects to maintain attitude and ...
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5 votes
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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 ...
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6 votes
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How does the chamber pressure affect the performance of a Rocket Engine?

I am under the assumption that higher chamber pressure results in increase in exhaust velocity. Is this true?
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3 votes
1 answer
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How can I calculate the density of Mars' atmosphere during dust storms?

I have been searching to try to estimate the air density of the atmosphere on Mars during a dust storm. I am trying to use this dynamic pressure equation to calculate the pressure on a theoretical ...
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1 vote
1 answer
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How to drink water on Mars?

There are craters filled with water on Mars as shown below. If fresh water is found, how would astronauts drink the water? Can the Apollo a spacesuit food/drink port be used to equalize the pressure ...
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1 vote
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Cryogenic liquid pressurization resulting in overpressurized tank

I want to pressurize a cryogenic liquid (LN2 in this test. Eventually LOX). I have a setup similar to this and follow a similar procedure to what is described, but I don’t see the same tank pressure ...
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2 votes
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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 ...
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ISS Destiny Module inner wall: thickness set by internal atmospheric pressure or by mass density needed for meteor shielding?

In their 2006 paper Christiansen et al. describe the "stuffed Whipple shield" wall of the ISS's Destiny Module. The outer skin, the Whipple shield's "bumper" layer, is a thin layer of aluminum (alloy ...
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What would happen if an astronaut walked on mars without a spacesuit i.e. wearing just earth clothes? [duplicate]

Which will happen first: Would she die due to lack of oxygen/suffocation or due to lack of pressure/boiling bodily fluids?
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3 votes
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Reliability of self pressurization of propellant tanks for liquid engines

In a cryogenic propellant tank, the liquid always continuously changes into gas which pressurizes the tank. To pressurize the tank more we can run the liquid through the pipes along the outer wall and ...
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24 votes
4 answers
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How could the 2018-08-30 Soyuz MS-09 / ISS leak be so slow?

The leak reportedly led the ISS to lose 0.8 millibars of air pressure per hour, which is both big considering what was at stake and low for a 2-mm hole when the outside is near to complete vacuum. Am ...
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9 votes
2 answers
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What is the deepest place on Mars? Do humans need pressurized suits there?

Is there any particular deep area, trench, fissure, lava tube or otherwise on of Mars in which a person could survive with only an oxygen supply? How deep would plants or animals have to be in Mars ...
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