Questions tagged [rockets]

Questions regarding the boosters or thrusters used to propel man-made objects. For rockets firing opposite the primaries, see [retrorockets]. See wiki for other related tags.

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If a company/agency has already developed a kerolox/hydrolox rocket, is it wise for them to switch to an all-methalox rocket? (to lower costs)

Multiple rockets, such as the Atlas V or Saturn V, have used the combination of a kerosene/liquid oxygen (kerolox) lower stage for higher density and thrust within the atmosphere and a liquid hydrogen/...
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2 votes
0 answers
99 views

What happens to the debris of a rocket that exploded or crashed? Is there a dedicated effort to cleaning the debris?

Assuming that everything is not vaporized, one would think that all waste is collected and incinerated. Does SpaceX, NASA, etc have a dedicated team/effort to cleaning up this debris?
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4 votes
0 answers
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Most open source spaceflight missions revealed unintentionally

As of 2021 there are few fully open source satellites (OSSI-1, UPSat, FossaSat-1, Oresat, some more?) and numerous student groups building and documenting rockets. These projects are intended to be ...
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3 votes
1 answer
308 views

Rocket engine with lowest Isp to reach orbit

Which engine with the lowest possible specific impulse has reached orbit propelling a given rocket? There is a page at Wikipedia that compares orbital engines but some engines are missing Isp value ...
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1 vote
1 answer
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What if we launched rockets from space using the slingshot method and centripetal force? Would that be possible?

Would we have to build a orbiting launch station that uses centripetal force to launch the rockets? Or a station that freely floats through space not in a planets orbit? Would something like this ...
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3 votes
0 answers
158 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.
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7 votes
7 answers
5k views

Are there any hand-sized rocket engines?

Are there any rocket engines that are small and light enough to be held in one or both hands? Gas, liquid and hybrid designs are fine but solid motors are excluded (with the exception of solids that ...
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2 votes
2 answers
155 views

How big is an orbit of "X by Y miles"?

While reading the NASA overview of Apollo 11, says: Apollo 11 launched from Cape Kennedy on July 16, 1969, carrying Commander Neil Armstrong, Command Module Pilot Michael Collins and Lunar Module ...
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4 votes
2 answers
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Rocket fuel cost to launch 1 kg to orbit

I have 2 questions about the cost of liquid rocket fuel to launch (anything) to LEO orbit. Let's assume we use fuels used in commercial spaceflight today (probably LOX+LH2 or LOX+RP-1 etc.). What is ...
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4 votes
0 answers
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What are the implications of North Korean black and white patterns on missiles?

Black and white patterns on rockets were originally intended as roll patterns. They helped as a visual back-up for acceleration sensors measuring the roll, as discussed in this previous question What ...
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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 ...
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5 votes
2 answers
306 views

Longest static fire?

What is the longest duration for a static fire of a complete rocket stage? Initially I wanted to ask this for Falcon 9 and Falcon Heavy I found a 10 second static fire for Falcon Heavy - https://...
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12 votes
3 answers
393 views

How big could a rocket get?

What are the practical limitations on the size of Earth based, orbital rockets? How tall/heavy might we make a rocket? For the purposes of this question, I'm mostly interested in rockets using ...
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3 votes
0 answers
92 views

Is steam a good gas to use for a small RCS thruster on a small rocket?

Is steam a reasonable tradeoff from other hot/cryogenic gases in order to have safety and have it easily obtainable? Thanks
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5 votes
1 answer
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Is there a distinct flame-front in a liquid-fuelled rocket combustion chamber?

Liquid fuel and liquid oxidizer are injected at high pressure through small orifices into the 'top' of a rocket's combustion chamber. The intention is that these mix quickly and then burn completely ...
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12 votes
2 answers
913 views

How do they determine dynamic pressure has hit a max?

Max-Q is a key event during launch, and dynamic pressure is closely monitored so they know when a max is hit. But how exactly do they know when Q hits a max? If you track the rate at which Q is ...
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1 vote
3 answers
331 views

How to make a model rocket that doesn't spin?

I'm attempting to build a rocket with 8 fins (four on bottom and four smaller ones towards the top). The four fins near to the top will be attached to servo motors and programmed to stabilize or guide ...
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3 votes
1 answer
116 views

How important is the convergence angle of a liquid bipropellant rocket engine

So I can't exactly find out what angle should the converging part of the rocket chamber be or why different angles are chosen for engines (varies by about 15°). Are there any guidlines on the angle or ...
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1 vote
0 answers
34 views

Does the displacement angle change after burnout?

I came across the above image on Nakka's page about fins and what I understood is that rockets will turn into the wind during the thrust phase, and will drift slightly with the wind after burnout. But ...
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1 vote
1 answer
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Why are some rockets painted black? [duplicate]

Why are Rocket Lab's and other rockets painted Black? Shouldn't they be painted white to reflect most light and therefore absorb less heat from sunlight?
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10 votes
10 answers
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Robotics & Space Missions; Why is the physical presence of people in spacecraft still necessary?

Robotics is now well developed. Many programming languages allow you to work in real-time. Also, a new era of space missions and research is in full swing. So here's the question: Why is the physical ...
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1 vote
1 answer
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Payload Capacity definition

Does the payload capacity of a rocket include the satellite and the adaptator or is it just the satellite ?
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1 vote
2 answers
109 views

How many times is a single rocket engine tested?

When a rocket engine is loaded into a test stand is it tested once before removal or is it allowed to cool and then tested again. Is every liquid-fueled rocket motor that flies to space first tested ...
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25 votes
4 answers
6k views

Why doesn't NASA release all the aerospace technology into public domain?

NASA is a publicly funded US governmental agency, yet it does not seem to release all the technology it develops into public domain for people being able to study it and learn from it. For instance, ...
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3 votes
3 answers
428 views

Can liquid rocket engines have the same thrust as solid rocket engines?

Take the Vega rocket launcher for example. Its first three stages are solid rocket engines and burn at a relatively short time. If I were to change its first stage into a liquid rocket engine, can ...
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10 votes
6 answers
2k views

When has hydrogen peroxide been used in rocketry?

Peroxide is apparently a very good propellant, but I can't seem to find any instance of it being used. Has it ever been used and if not, why hasn't it? What's its downsides?
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3 votes
1 answer
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What happened to continuously-applied heat barrier coatings in engines?

In Ignition, Clark describes an interesting approach to thermal control in rocket engines using oxygen as an oxidizer and hydrocarbon fuel: A small amount (few percent) of silicone oil or another ...
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1 vote
1 answer
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Small liquid rockets are hard/expensive to build, but what about to use them?

It's become a sad and oft-demoralizing truism that it's quite difficult and expensive to design or build even low-performance liquid-fueled rocket engines, and that amateurs -- even those with skills ...
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4 votes
5 answers
1k views

Why is specific impulse equivalent to effective exhaust velocity?

I am very comfortable with specific impulse in seconds. I know how to calculate it, I know what it is, I know what happens to a rocket when you double in or cut it in half. But it feels like the ...
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4 votes
2 answers
570 views

Design of starship fins

How much can the falling speed of starship approximately be reduced by the bellyflop fall with fins? Are we talking about numbers around 5% or 50% here? Wouldn't it make sense to put holes where the ...
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6 votes
5 answers
2k views

Using of the rocket propellant for engine cooling

Why does liquid space propellant make a good engine coolant? I was researching the regeneratively cooled nozzle and combustion chamber on the Merlin 1D when I found this out. I do know that the pipes ...
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-2 votes
2 answers
147 views

Can we just throw a satellite in to mars orbit with a very high spin?

I am thinking about this scenario of throwing a satellite to Mars orbit with a high spin, Can we just throw that? one hypothesis can be that high-frequency spinning generates apparent gravity so it ...
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8 votes
1 answer
286 views

Why do some rockets have closed boattails around the engines and others do not?

During launch and landing, dust, dirt and debris may be stirred up. For non-gimbaling engines like the vac Raptors on Starship, can't the engine fairing/boattail be closed? I imagine titanium sheet ...
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5 votes
0 answers
101 views

Have any stages of rocket killed aquatic animals?

This question may seem off-topic but I am curious.Those rockets that aren't reusable let their stages fall and splash down on the ocean. Is there any news reported that they have killed some aquatic ...
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19 votes
1 answer
2k views

What happens to where umbilical lines are connected when a rocket lifts off?

I've read about umbilical lines in rockets but I don't understand what happens with the places where each umbilical is connected to the rocket once it lifts off. I guess they are sealed in some way in ...
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18 votes
1 answer
2k views

Why is the tip of this Russian ICBM folding/closing during launch?

This question refers to the page on which a YouTube video Soviet Missile SS-18 Satan / Most Powerful Rocket is shown. Screenshots below are from circa 01:10 for ...
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2 votes
1 answer
273 views

How do we maintain the RPM of turbo pumps in liquid rocket engine?

How do we maintain the RPM of turbo pumps in liquid rocket engine? And how do we control it? And in the case of electric pump fed engine (like Rocket Labs's Rutherford engine) is easy but how we do it ...
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8 votes
2 answers
361 views

What is a throat plug used for?

This cutaway drawing of the F-1 injector plate has a "throat plug insert" annotated. What is a throat plug? What is it used for?
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15 votes
1 answer
2k views

Why is butane never used in rockets as fuel?

From what I know, it seems good, so why does no one use butane as a rocket fuel?
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4 votes
2 answers
144 views

Let's say I build an orbit-capable launch vehicle, what tests/certifications would the LV have to acquire to be allowed to launch payloads into orbit?

For the purpose of the question, let's assume said launch vehicle is 100% identical to Electron. What sort of tests/certifications would I have to send the rocket through in order to make it legal to ...
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2 votes
1 answer
124 views

Merlin 1-D Vacuum - Side Exhaust Noted in Flight Videos

During the Falcon 9 second stage firing of the Merlin 1D Vac engine, the video shows an exhaust plume ejecting from near the top of the nozzle bell, and canted outward (say 10 degrees) from the bell. ...
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8 votes
3 answers
4k views

Which theoretical propulsion system has the highest specific impulse?

I know that NERVA physically demonstrated 811 seconds, and the theoretical range for Orion was around 10,000. After stipulating that we can't really know for sure until it's built, given plausible ...
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2 votes
1 answer
113 views

What is the effect of poorly choosing L* in combustion chamber design?

I am a member of a university rocketry club and we are in the process of designing a liquid rocket engine. One of the previous propulsion leads did the primary conceptual design of this engine in RPA. ...
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1 vote
1 answer
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I'm having a problem with the Throat Area formula derivation

I came upon this when reading "Introduction to Rocket Science and Engineering, he said "by differentiating" , my question is: differentiate with respect to what? and how do you get such ...
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6 votes
2 answers
929 views

How do launch vehicles measure speed during lift off and ascent?

What kind of instruments does a rocket use to track its trajectory and velocity during ascent? Do they use pitot tubes or barometric sensors? What exactly are the instruments used?
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3 votes
2 answers
631 views

Isentropic flow through a rocket nozzle and constant mass flow rate

The definition of isentropic flow is that the flow is both adiabatic (no heat is transferred into or out of it) and reversible (energy is conserved in it). I am wondering why the flow through a rocket ...
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2 votes
1 answer
139 views

Why maintain nominal engine inlet mixture ratio for a gas generator engine?

I was reading up on gas generator cycles and came across the following paragraph talking about fuel or oxidizer rich gas generators and the different mixture ratios for the main combustion chamber ...
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6 votes
1 answer
179 views

Electron rocket holding & releasing mechanism

Launch vehicles generally include a holding & releasing mechanism so that it will not leave the ground until proper engine function is confirmed and stable and sufficient thrust is achieved. These ...
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12 votes
2 answers
2k views

Is there such a thing as a "rocket license" in the US?

I heard in a video that a 15 year old got their rocket license before getting driving license. The video does not explain further; but what I'd like to know is: *In the US, is there any such a thing ...
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4 votes
1 answer
102 views

How to experimentally determine the degree of atomization of the propellants mixing in a fuel injector?

When validating a fuel injector design on a test stand using liquid water to simulate a liquid-liquid fuel injector(the one i'm working with currently is a pintle design but I suppose one could ...
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