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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37 votes
4 answers
15k views

Effect of atmospheric drag on rocket launches and benefits of high altitude launch sites

What is the approximate influence of atmospheric drag on the cost of rocket launches? Is it beneficial to have launch sites located at higher altitudes? Cape Canaveral is at sea level, but I've ...
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89 votes
6 answers
16k views

How much bigger could Earth be, before rockets wouldn't work?

hint: Apparently the Tsiolkovsky rocket equation does not actually say that you can launch a conventional rocket into orbit around an arbitrarily large and massive body. I'm looking for a number ...
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36 votes
9 answers
13k views

Why do rocket nozzles flare?

Why do rocket nozzles open wider at the end than, let's say, get narrower? Let me explain: A jet engine works by having this amazing thing called a combustion chamber. The combustion chamber ignites ...
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24 votes
2 answers
34k views

Launch Accelerations: Values, history

This topic: What G-forces do different launchers cause? indicates that current satellite launchers are limiting peak acceleration to about 4g. I'm pretty sure the STS (Shuttle) did the same. My ...
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29 votes
4 answers
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How small could an orbital rocket be?

To what extent might a booster designed to place an extremely light weight "micro" satellite with radio transmitter, say 100 grams for the sake of argument, be scaled down before factors such as ...
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10 votes
1 answer
996 views

How do rocket propellant combinations rank in terms of "brightness"?

While a booster on the shuttle had a bit more than twice the thrust of the shuttles engines at take-off, I'd venture a guess that it produced on the order of a thousand time more visible light. In ...
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114 votes
4 answers
19k views

What is the purpose of having a countdown during a rocket launch?

Every rocket launch has a countdown. But what purpose does it serve?
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11 votes
3 answers
2k views

Is it normal for thrusters to "ice up"?

Towards the end of the JSSAT-14 webcast (around T+32:58), we see a thruster firing. Over the space of around 20 seconds, you can see it "icing up": What is this that's forming? Is this a normal ...
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9 votes
3 answers
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How might SpinLaunch actually spin something fast enough to launch it into orbit?

update: TechCrunch's SpinLaunch spins up a $35M round to continue building its space catapult is worth a read and contains this cool rendering. Click for full size Ars Technica's Edition 1.34 of the ...
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12 votes
5 answers
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Why isn't there a rocket to launch a single cubesat?

I find the business model for RocketLab interesting. It is said that they fill a niche in the market by using smaller rockets. And it is true, in comparison to e.g. Falcon 9's payload of 9,500 kg, ...
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16 votes
1 answer
1k views

Cause of apparent plume deflection on SES-10?

While watching the SES-10 flight, starting a little after T+1:30, I noticed that the direction of the first-stage exhaust plume started to diverge from the alignment of the rocket body. The ...
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10 votes
4 answers
6k views

Why does spinning help stabilisation?

I don't really understand why do we use spin stabilisation for rocket launches? If I understand correctly, the idea is to make the rocket spin really fast so that any asymmetry in the thrust/...
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10 votes
3 answers
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On a Super-Earth 1.5x the volume and mass of Earth, would our rocket technology allow us to reach orbit? [duplicate]

To try and make parameters clear, can we say we are talking about 50% 'more Earth'? As in, Earth, but 1.5 times as big and heavy? And let us include the atmosphere. If there is 50% more of it by ...
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4 votes
4 answers
834 views

Does "What happens beyond Kármán, stay beyond Kármán"?

The title refers to the promotional slogan "What happens in Vegas, stays in Vegas." The question How much CO2 would city-to-city rocket flight produce compared to airliners? seems to be focused on ...
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27 votes
5 answers
62k views

Is it possible to reach space using home-made rocket?

The first stage would be a high altitude balloon, which could reach 30km. Then start a rocket-candy from that high. Without cargo, is it possible to reach the edge of space (Kármán line - 100km), or ...
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21 votes
4 answers
6k views

How does a simple construction keep a firing rocket on the ground?

Today I have seen this report of a SpaceX Falcon 9 rocket test firing. The force of a burning rocket is tremendous, and in the video we see an apparently simple construction keeping the rocket (or ...
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9 votes
4 answers
5k views

Is there a maximum Isp for "exothermic chemical reaction rockets"?

The question Is there a maximum $\text{I}_{sp}$? reminded me that I once read somewhere that the maximum possible $\text{I}_{sp}$ for a rocket engine based on expansion driven by exothermic, ...
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  • 148k
13 votes
1 answer
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How would the Saturn V have differed if the first stage was also LH2/LOX?

Since both Kerosene (RP-1) and liquid hydrogen (LH2) continue to be important liquid fuels used with liquid oxygen (LOX), something can be learned by comparing how they are used. This is covered well ...
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3 votes
1 answer
4k views

How can I estimate the Coefficient of Drag on a Saturn V rocket, a simulator or some data would be pretty awesome

I'm trying to get some information on this and its proving difficult as the information is usually acquired experimentally from what I've found. A single number at a specific altitude and speed would ...
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21 votes
2 answers
23k views

Could I build my own spaceship?

We all know that for most people access to space is currently pretty limited because space flight services are expensive, as they are in short supply. Suppose I wanted to bypass an expensive service ...
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25 votes
1 answer
4k views

Do all launches include self-destruct mechanisms?

Do all launches involve self-destruct mechanisms? How do they usually work? Is it just the boosters that are required to self-destruct? In the case of the space shuttle, how about the external tank? ...
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41 votes
2 answers
73k views

What is the vapour/smoke that comes from a rocket before launch?

While a rocket is waiting on the platform during the final countdown, it often seems to have clouds of steam or something similar escaping from it. Is this normal, and what are these clouds?
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21 votes
3 answers
7k views

Could 3D printing be used to achieve perfect grain geometry of solid and hybrid rocket motors?

Solid cores, either for solid-fueled of hybrid rocket motors, use various propellant grain geometries to achieve thrust curve needed. For example, some of these could look like:    &...
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31 votes
3 answers
18k views

Why are hydrogen-fluorine fuels not used for rockets more frequently?

Many rockets use hydrogen- and oxygen-based propellants as fuel. Why are hydrogen-fluorine fuels not used? It has a specific impulse of 390 seconds, higher than hydrogen-oxygen combustion (360 ...
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  • 18k
30 votes
3 answers
13k views

What is the purpose of the black-and-white patterns on some rockets?

Some rockets have black-and-white patterns painted on them. For example, the Saturn V has them at the bottom of the upper stages and the SLS block 2 is supposed to have them below the payload. In ...
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7 votes
4 answers
2k views

Is aerodynamic lift ever useful in rocket flight?

When a rocket is traveling through an atmosphere, the component of the aerodynamic force in the direction of motion is called drag, and the component perpendicular to that is called lift. Usually a ...
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12 votes
4 answers
3k views

Do rocket engines have shock absorbers?

With a million pounds of thrust and many g of acceleration and a significant fraction of a g of vibration, connecting the engine to the rocket can't be trivial. At launch the mass is very high and ...
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37 votes
4 answers
12k views

Why is there a hole in solid rocket engines?

I would like to find out why there is a straight hole down the middle in all solid rocket engine motors. I thought it only makes sense in hybrid engines where pure oxygen needs to be blown down the ...
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15 votes
3 answers
4k views

Is this a correct understanding of Tsiolkovsky's rocket equation?

When I graph the rocket equation, substituting arbitrary values for v(exhaust) and m1, so m0 because m1 - m0, the graph implies that increasing propellant mass past a certain point does not increase ...
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  • 433
39 votes
4 answers
10k views

What "actually" happens at T-minus-0

In most American rocket launches, the "counter" will say: 3,2,1 [awkward pause], and liftoff.... So what truly happens at T-0? Is there any standardized event that this time indicates? Is the ...
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  • 1,685
33 votes
3 answers
6k views

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?

Why do the exhaust flames from cryogenic stage engines appear to be separated from the nozzle?
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  • 18k
41 votes
1 answer
5k views

Why do the Russians use these fence-like interstage fairings?

When we look at various Russian rockets we often see a metal structure looking like a kind of garden fence separating some stages. To my knowledge, only the R7 family (Vostok, Voshkod, Soyuz) and N1 ...
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26 votes
2 answers
9k views

Does launching a device into orbit change earth's orbit?

Does launching a space shuttle or rocket change the earth's orbit? After all, to get momentum in space you need to throw something out.
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14 votes
2 answers
5k views

Is it possible for the Space Shuttle Solid Rocket Boosters (SRB) to hit the Space Shuttle after jettison?

We all know that the Space Shuttle Solid Rocket Boosters (SRB) were the pair of large solid rockets used by the United States' NASA Space Shuttle during the first two minutes of its powered flight. ...
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32 votes
1 answer
3k views

Why do the Shuttle's external tanks appear to be rusted?

Wikipedia article states as STS-1 at liftoff. The External Tank was painted white for the first two Space Shuttle launches. From STS-3 on, it was left unpainted. I wonder why the ...
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  • 18k
21 votes
3 answers
4k views

How are fuel tanks filled with cryogenic hydrogen?

Cryogenic hydrogen can react with the atmospheric Oxygen to produce an explosion: as well as being cold enough to liquefy (and possibly solidify) atmospheric oxygen, which can be an explosion ...
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16 votes
3 answers
1k views

Why do we use the gravitational acceleration at the Earth's surface when calculating the specific impulse of an engine?

So one of the ways of calculating Isp is: $$I_{sp} = V_e /g_0 $$ You divide the effective exhaust velocity by acceleration at earth's surface. This gives you a number in seconds, and is generally ...
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13 votes
1 answer
2k views

Why are rocket launches so loud?

In reading an answer here: How close can I get to a rocket launch and not get killed?, the comment is made that noise from the launch can be tremendous. This isn't a big surprise to anyone who's ...
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2 votes
2 answers
722 views

Rocket drag and lift based on flight direction - in which frame of reference?

Drag is aerodynamic force component parallel to the direction of motion. Lift is aerodynamic force component perpendicular to the direction of motion. Direction of motion with respect to what? 1) ...
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  • 148k
20 votes
1 answer
2k views

What was the purpose of the small red tank attached to the Titan-Centaur launcher?

Watching a documentary on the Viking missions, I noticed the launcher had a small red tank/rocket attached to one of the solid boosters. It struck me as an odd feature/placement, as I thought you'd ...
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  • 515
16 votes
11 answers
16k views

Highest number of satellites launched on a single rocket

What is the highest number of satellites that have been launched on a single rocket? What were the number of stages used in that launch? (It may be from the past or a future mission)
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  • 18k
15 votes
2 answers
6k views

Are rocket exhaust flames ever opaque?

The flame exiting the space shuttle main engine is obviously transparent. But, you can't see objects through either the Saturn V booster flame or that of the space shuttle solid rocket boosters. Is it ...
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12 votes
1 answer
8k views

How are rocket nozzles made?

How are rocket nozzles made?? Is it a huge chunk of metal that they cut down or is it a "pipe" that they reshape? Or something else??
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  • 1,685
8 votes
3 answers
12k views

What does the exhaust plume of a rocket look like in vacuum?

There are plenty of photos of rocket tests and launches in atmosphere, and in these the exhaust plume tends to be a long thin flame. Is this true for when rocket engines operate in a vacuum? My guess ...
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8 votes
1 answer
4k views

Where is the optimal location to launch payloads to outer space?

Imaginary scenario: The US, Russia, China, Europe, India, and all the private space companies in between combine resources for a sustained space exploration program beyond Earth. They can choose any ...
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15 votes
1 answer
7k views

Why did Apollo use roll and pitch maneuvers similar to Space Shuttle to establish ascent trajectory?

When the Space Shuttle launched, it would perform a roll and then pitch to establish its ascent trajectory. There is fairly straightforward rationale for this. The vehicle's aerodynamic shape, the ...
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14 votes
4 answers
3k views

Why are rocket mass on the launch pad and payload mass to LEO not strongly correlated?

What explains the relation between how much a launcher weights on the launch pad, and how much mass it can lift to orbit? I had expected that more payload requires more fuel to be launched and that a ...
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  • 26.4k
4 votes
2 answers
666 views

Rocket to launch 8 cubesat to LEO at an equidistant distance

I am working on a project, which consists of the launch of 8 cubesat 1U to LEO (Low Earth Orbit) and I started working on the launch part, the idea of ​​the project is to be as cheap as possible, the ...
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17 votes
1 answer
4k views

What does "in the bucket" mean?

I've heard this expression a couple of times before. It seems related to the engines, but I can't find any information on it, except in the context of testing them. Here's two videos where it occurs: ...
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15 votes
1 answer
1k views

How are self-destructs implemented in rocketry?

Many rocket systems are equipped with self-destructs to prevent an out-of-control vehicle from wandering too far from its intended path and becoming a hazard. Presumably, the objective is to kill the ...
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