Questions tagged [thermodynamics]

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5
votes
2answers
108 views

Does adding a nozzle increase peak pressure in a rocket?

If I had two charges of the same solid propellant both in the same geometry and casing, and added a de laval nozzle to one, while the other would have just a simple hole for an exhaust, upon firing, ...
5
votes
1answer
120 views

What would a candle flame look like in low gravity?

We know what the flame of a candle looks like on Earth in 1g and what it looks like in weightlessness. But do we have an idea of what it would look like in Lunar (0.166 g) or Martian (0.38 g) gravity? ...
2
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2answers
257 views

What is the shielding capability of liquid metal compaired to solid metal?

For simplicity, consider a spherical metal shape for shielding cargo/people behind. (The liquid ball is supposed to be between the Sun and the cargo. Not people inside it.) A problem I see is that it ...
1
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0answers
55 views

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 ...
-1
votes
1answer
90 views

What is the vapor pressure limit of liquid metals in space?

Would liquid metal be stable in space unlike most other liquids like water? Are there any metals that has a high vapor pressure limit? Side question: Can liquid metal be given an electromagnetic ...
2
votes
1answer
114 views

How cold was it in the shade of the Parker solar probe?

What was the temperature in the shade of the Parker solar probe? Do to the proximity at the closest point the probe got to the Sun how much shade can be produced at that range?
2
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1answer
232 views

Parker Solar probe jumping through fire?

Is the principle of passing close the Sun with the Parker Solar probe the same as if you pass your hand over a candle flame fast enough you won't get burned?
2
votes
1answer
394 views

Martian Carbon Dioxide Turbine Oxygen Generator

How much solid Carbon Dioxide can be collected in a container with the top of the container level with the ground during a Martian Winter? Side Question: What do you call a generator that runs on the ...
1
vote
1answer
285 views

What is the maximum speed can a space rocket can travel with an air pressure of 14psi? [closed]

What is the highest threshold speed of a space rocket traveling in an air pressure of 14psi with all of its stages if they where able to leave a solo at Mach 1 or more? Related: What benefits can be ...
2
votes
3answers
144 views

Can you avoid thermodynamic inefficiencies in space propulsion?

In @David Hammen's answer to this question, he highlights the discrepancy between the exhaust velocity that would be achieved by converting all the chemical energy of the fuel into KE of the exhaust (...
1
vote
1answer
255 views

new nozzle design, is it a fail?

So I'm an amature rocket scientist. while having a conversation with a friend on a nozzles we though of a new nozzle: Its a double nozzle where it expands a lot and then compress. I want to put this ...
5
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0answers
108 views

What aerothermal effects present significant challenges in supersonic retropropulsion?

One of NASA's plans for future mars entry, descent and landing missions includes an ambitious deceleration process involving retropropulsion in a supersonic airflow environment. I know that previous ...
2
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1answer
403 views

Controlling Combustion Chamber Pressure

When designing a rocket engine, what degrees of freedom do you have to get the combustion chamber to a desired pressure? I assume you have mass flow rate, type and mixture ratio of fuel and oxidizer, ...
5
votes
3answers
755 views

Could thermal energy be collected by dragging a thermoconductive device against the outer atmosphere

Atmospheric reentry is notoriously a difficult and HOT endevour. Could this thermal energy be used as an alternative energy source on earth? Could this be used through some sort of orbital charging ...
5
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2answers
3k views

What does “self-pressurizing” mean in regards to propellant tanks?

I've come across this term a few times. IIRC, liquid hydrogen is "self-pressurizing", but other fuels are not. Apparently, if a propellant is self-pressurizing, we do not need to build any complex ...
18
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1answer
4k views

Why aren't the ISS's nor Space Shuttle's radiators black?

As we know, from a surprising corollary to Kirchhoff's law of thermal radiation, just as darker* objects absorb more light (and therefore energy), darker objects also radiate more light (at lower ...
8
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4answers
2k views

What is the barometric formula for a gas giant?

The barometric formula describes the atmospheric pressure depending on height and a host of other things. This formula assumes a constant gravitational acceleration over the whole height of the gas ...
6
votes
1answer
422 views

How do space-bound heaters work?

A brief follow-up to Could Rosetta have been awakened from Earth if necessary? The Rosetta FAQ writes to say Q. Was Rosetta completely shut down? Almost. Only the computer and several ...