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Questions tagged [engine-design]

Questions regarding the design or design process for a propulsion system.

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67
votes
10answers
43k views

Why is SpaceX considering Methane as fuel for their next engine, the Raptor?

Currently, SpaceX has developed the Merlin 1 family (1B (Falcon 1), 1C (Falcon 9 v1.0), 1D (Falcon 9 v1.1/F9-R/Falcon Heavy), vacuum versions and sealevel versions) which are LOX/RP1 based. (75-...
37
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3answers
11k views

Why are rocket engines operating above 100% often considered nominal?

It was brought to the attention of the community that right before the crash of Antares the commentator noted: "Main engines at 108%" It was noted that other engines were also reported to work at ...
32
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6answers
6k views

Why did it take so long for methane to be used as a rocket propellant?

SpaceX have put methane on the map as a rocket fuel, but they weren't the first to consider its use. The first experiments in building a rocket engine that uses methane date back to 2007. Now methane ...
29
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2answers
5k views

Why cool engines with fuel as opposed to oxidizer?

As I was watching Tom Mueller describe the Merlin engine, he said that the RP-1 propellant is pumped through ribs in the nozzle to regeneratively cool the engine. Also, a video about Copenhagen ...
28
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7answers
12k views

Why are Rocket engines at the base of the rocket?

I don't know much about Rockets, but all that I have seen, from the Saturn V to SpaceX's Falcon 9 have the engine at the bottom. Doesn't this make the Rocket really unstable, like balancing a pencil ...
27
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4answers
4k views

Does the NK-33 engine require subcooled kerosene so cold that it turns to wax?

It was mentioned in this answer and in several other places on the internet that the kerosene fuel used by NK-33 engines needed to be subcooled enough so that it reached the same density as the LOX, ...
26
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3answers
7k views

Why doesn't the US use European rocket engines?

US Companies have been using Russian rocket engines for their rockets for a long time, even during sanctions. But as I was going through the European rocket launches, I felt European rocket engines ...
25
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9answers
6k views

Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?

I am wondering if any space agency has ever considered using a grinding machine as a propulsion system for an interplanetary spacecraft. This system would not be used to lift the spacecraft off of a ...
24
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1answer
2k views

How realistic would the Sea Dragon engine be to produce given today's technology?

Just learned of the Sea Dragon proposal from back in 1962. From the Wikipedia entry The first stage was to be powered by a single enormous 80,000,000 pounds-force (360 MN) thrust engine burning RP-...
23
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7answers
15k views

Why aren't linear aerospike engines in common use?

Linear aerospike engines are an old idea that seem so full of promise. Why are they not widely used today by the likes of Boeing, SpaceX, etc.?
23
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3answers
18k views

What's so special about SpaceX's Raptor rocket engine with 300 Bar chamber pressure?

What allows the Raptor engine to have a high chamber pressure of 300 Bar? Compared to other rocket engines which have been or that are now operational, it has the highest chamber pressure. What does ...
21
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2answers
3k views

Are nuclear-powered engines the way to go for space exploration?

I often think about the future of humanity and how to achieve it. Despite criticism, the USA and USSR achieved significant scientific breakthroughs, such as: putting the first man in space landing ...
20
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4answers
760 views

Could a rocket engine be designed to use different fuels? (Like LOX+H2, LOX+CH4)

I'm obviously not a rocket scientist, so this might rank among the stoopidest questions around here. I wonder if it is feasible to design a rocket engine which could be reused in space by refilling it ...
20
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1answer
5k views

Why is the SABRE engine curved?

Why is the Reaction Engines Limited SABRE (Synergistic Air-Breathing Rocket Engine) curved along it's length?     Illustration of the SABRE engine with the pre-cooler heat ...
19
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7answers
10k views

Can ion thrusters be scaled up?

All ion thrusters are quite small. Having read through the more approachable information about them, as they use physics pretty beyond me, I don't understand what it is about them that makes it ...
18
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2answers
3k views

Was the third shuttle engine any different from the others?

The space shuttle used three SSME, organized in a triangle with two next to each other closest to the external tank, and one on top of those. I am pretty sure the first two engines were close to ...
18
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1answer
3k views

Why design new rocket engines instead of using the existing types?

Already in the 1960s rocket engines seem to have achieved near maximum chemical efficiency. What are the reasons for new designs being in demand? How much better could a new engine design be than the ...
18
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2answers
3k views

Why do pressure fed engines have combustion instabilities?

Reading about the Sea Dragon idea, I came upon this argument against it, which sounds compelling, but relies on more detailed knowledge than I have: Those are to be pressure-fed to avoid "...
17
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2answers
1k views

How do you confirm ignition in the combustion chamber of a rocket?

Is ignition confirmed using a temperature sensor, pressure sensor or another device?
17
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1answer
2k views

Why the non-symmetric design of rocket nozzles?

Although I have seen many perfectly symmetric nozzles, I have also seen designs such as this (Virgin Galactic) which is only symmetrical about one axis: Why is this?
16
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1answer
9k views

Why is the Russian approach to the aerodynamics of their rockets different?

Russian rockets look like this: They flare them out at the bottom. With their newest rocket, the Proton, the flared shape is gone but the boosters still have caps that angle in towards the main ...
16
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3answers
922 views

Pumped propellant propulsion - is it viable?

A recent article on Slashdot got me thinking. While the article is about using electric turbopumps for moving fuel from tanks to engines during launch phase and is just a small, incremental ...
14
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5answers
4k views

Have Air-breathing Engines ever been used on a reentry vehicle, could they be?

For the purpose of this question I would like to assume there is no risk of life for the astronauts, or that the design would only be used for delivery of a non-ethically-sensitive payload. Looking at ...
14
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2answers
3k views

Benefit of Raptor Engines

I know that the Raptor engines are significantly different from the Merlin 1-D's since they use liquid methane and are cryogenic. However, what exactly enables the Raptor engines to produce a lot more ...
14
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1answer
2k views

What is that second (smoke) exhaust on a rocket engine for?

In this video of a Korea Aerospace Research Institute (KARI) rocket engine test, you can clearly see a second exhaust where thick smoke comes out. Is this an essential part of the engine, or just an ...
14
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1answer
2k views

What NASA documents did SpaceX use to design their engines?

I've watched this (excellent) panel discussion titled 'Our Future in Space'. Bill Nye says at 22:48 that SpaceX got their engine design from work done by NASA, which they developed into a working ...
14
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1answer
1k views

Is there any rule for rocket engine nozzle proximity from each other?

I wonder if there is any rule for how closely you can put engine nozzles to each other. Are there any vibration, heat, etc. constraints when you are assembling two or more engine bells together? ...
14
votes
1answer
722 views

At what travel distances are ion engines faster and more efficient than conventional fuel engines?

According to Scientific American (February 2009), ion engines start off slow, but build up speed as they travel. At what travel distance would an ion engine (such as an ion thruster, a Hall thruster, ...
14
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1answer
2k views

Changes made to ISRO GSLV-D5's CUS and FBTP since GSLV-D3's LH2/LOX CUS failure to sustain ignition?

The launch of the ISRO GSLV-D5 launching India's GSAT 14 advanced communications satellite (weighing 1,980 kg) is slated for 19th of August, 2013, flying in the GSLV Mk.2 configuration with an Indian-...
13
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4answers
12k views

Why don't rockets drive the turbopump from the combustion chamber?

As I understand it, liquid-fueled rockets typically burn some amount of their fuel in a separate low-pressure combustion chamber, and then use the combustion products produced to drive the turbopump. ...
13
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4answers
2k views

What are the consequences of NASA validating this “impossible” space drive?

A British inventor invented an engine that can provide thrust in outer space without a propellant. This engine has been tested by a Chinese team, and more recently by NASA: The engine itself is The ...
13
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5answers
4k views

Can a rocket motor be shut off after ignition?

After ignition, if any problems occur such as fuel leakage, can a rocket motor can be shut off?
13
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2answers
16k views

Efficient types of nozzles used in rockets

Is there any other type of nozzle other than common convergent-divergent nozzle (see picture below) which is used in many rockets?             ...
13
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1answer
2k views

Are MMH and UDMH interchangeable?

Can Monomethylhydrazine and Unsymmetrical dimethylhydrazine be used one in place of another for the class of the existing orbital maneuver engines (with reduced performance may be)? Such as Shuttle's ...
12
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3answers
3k views

Did any rockets use differential throttling instead of gimbal?

It seems the standard approach to control of rockets during launch is either vernier thrusters, or gimbals on the main engines. Sure that works, and is quite efficient, but I wonder about a simpler ...
12
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1answer
2k views

The principle behind regenerative cooling?

In regenerative cooling the fuel is passed around the nozzle before being pumped into the combustion chamber right? I don't really see how this affects cooling itself, since the heat captured around ...
12
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4answers
1k views

SpaceX's ITS - why gimbal only the inner cluster?

Does anyone know the reason why, in SpaceX's newly-announced ITS launch vehicle, only the inner cluster gimbals, and not the whole engine system?
12
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1answer
3k 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??
12
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2answers
3k views

Why the huge thrust difference between a Sea level and Vacuum J-2 engine?

Looking at the Wikipedia page for the J-2 (one engine was used on the Saturn V third stage, and 5 engines on the second stage) it gets about 232Klbs thrust in vacuum, but at sea level, only 109KLbs ...
12
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2answers
2k views

Quality vs. Quantity for Rocket Engines

I read a while ago about the famous Soviet N-1, called by some the most powerful rocket (in terms of thrust at liftoff) in history. It used an incredible 30 engines in its first stage. The American ...
12
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1answer
2k views

Why was the Apollo CM main engine thought to be unreliable on Apollo 13?

When Apollo 13 had most of its internal systems destroyed by an explosion, NASA decided that the best course of action would be to fire the main engine on the dark side of the moon to send the capsule ...
12
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1answer
2k views

Merlin 1D Engine Throttling

How does the SpaceX Merlin engine control the mass flow rate to throttle its thrust? Do the pintle injectors move? Does the mass flow rate to the gas generator change?
12
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2answers
1k views

Did the Apollo F-1 engines gain weight during flight?

I was browsing through Wikipedia when I came across this infographic on the Rocketdyne F-1. It gives the engine dry weight as 18,500 pounds, and the engine burnout weight as 20,180 pounds, meaning the ...
12
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2answers
2k views

Disposition of the Oxidizer Tank in Rockets with Autogenous Pressurization

A little while ago, Ars Technica did a big story on the Firefly rocket under development. http://arstechnica.com/science/2014/11/firefly-space-systems-charges-full-speed-toward-low-earth-orbit/2/ A ...
11
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2answers
1k views

How will the SLS first stage be supplied with engines? Copy manufacturing the RS-25 or replacing it?

The SLS is a very opinionated subject among bloggers. I'm looking for what substance there might be behind the following general claim (without specific source). Is it truthful and if so, what is the ...
11
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4answers
2k 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 ...
11
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1answer
3k views

What is the temperature inside a methane/oxygen rocket engine?

Assuming a simple rocket engine, with a combustion chamber and de laval nozzle, fueled by liquid methane and liquid oxygen, what temperature must the combustion chamber, choke and nozzle withstand? ...
11
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1answer
634 views

Why does the YF-75D nozzle have such a strong spiral pattern?

Why does the YF-75D nozzle material have such a strong spiral pattern? Is it a result/biproduct of a manufacturing process only, or does it have some specific function? edit: The last, cropped ...
10
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4answers
3k views

How does a thin metal rocket engine not get crushed by the weight of the flying rocket?

It looks like a liquid fuel rocket engine is made of rather thin metal. Here's photo of RD-107 from Wikipedia Nothing personal, but it looks like it's made of several shiny thin metal cans (connected ...
10
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3answers
2k views

What are the phases of ignition (and flameout) of a liquid fuel engine?

As I observed ignition of several rocket engines (Shuttle, AMDE, Lynx Suborbital, Saturn V) they all come through a couple phases - emitting various vapors, unfocused flame, etc, before the proper "...