Questions tagged [engines]

Questions regarding equipment used to propel a spacecraft or a rocket. Questions about attitude control jets should be tagged "attitude".

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8
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1answer
466 views

What is the job of the acoustic cavities inside the main combustion chamber?

I am new to rocket engines. I was looking at an image of RS-25 engine's MCC and found these acoustic cavities, and I want to know how they work. Can somebody please explain their working principle? ...
4
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2answers
613 views

Compressed gas thruster for an orbital launch vehicle?

Is it possible for a compressed gas thruster to be used to launch a spacecraft into orbit? Let's say, it's already moving at 250MPH(111.7 meters/second) relative to the planets surface. Planets ...
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0answers
28 views

Would a nuclear turbojet with a chemical afterburner be a suitable intermediate between a pure nuclear turbojet and a nuclear thermal rocket?

NOTE: This is not the place to question the fundamental veracity of nuclear propulsion in aircraft and spacecraft. For context, in a spaceplane, the higher speeds you can attain under air-breathing ...
3
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1answer
112 views

Are there any rocket engines in current or former use that aren’t normally restarted in flight, but have the capability for an emergency restart?

(Inspired by my earlier question about restarting a flamed-out RS-25 SSME in flight.) Most rocket engines are not designed to be lit more than once.1 Most first-stage rocket engines, for that matter,...
6
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1answer
87 views

Are rocket engine feed pipes flexible?

Let's restrict this question to rockets whose first stage : run on liquid propellant use turbopump (this may be too restrictive for this question, but it still restrict to many rockets in use today -...
2
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2answers
66 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?...
4
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2answers
145 views

Why did the manned Mercury-Redstone flights carry and use retrorockets?

The Mercury-Redstone programme, a subset of the Mercury human spaceflight programme, used a modified version of the Redstone missile for suborbital flights in space. It culminated in two manned ...
4
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2answers
82 views

Apollo CSM RCS maximum number of simultaneously active engines?

Reading the RCS subsystem manual, it seems like each RCS quad of the Apollo SM consisted of four hypergolic engines. Am I correct in saying that all four engines of each of the four quads could be ...
6
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1answer
60 views

Apollo CSM mass, inertia and RCS parameters?

Is there a document specifying the total mass, the 3-by-3 inertia tensor of the Apollo CSM assembly, as well as the geometry of the service module and command module RCS assemblies (in other words, ...
9
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2answers
756 views

Why could the Lunar Ascent Engine be used only once?

The Lunar Ascent Engine was used during the Apollo missions to ascent from the lunar surface back to the Command and Service Module. There was one risky aspect of that engine: it was not possible to ...
3
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0answers
50 views

Does engine purging cause dry run of turbo pump in a liquid rocket engine? If it occurs, what is the implication?

Does engine purging in a liquid rocket engine cause dry run of the turbopump? If so, does that have any implication for the design, health, maintenance, or operation of the pump? How do we calculate ...
3
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1answer
93 views

Can the ISS boost maneuver engine be heard by the astronauts on board?

In the extremely cool demonstration video Demonstration of Acceleration Inside the International Space Station During a Reboost ISS Expedition 22 Commander Jeffry Williams says near the end at ...
7
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3answers
777 views

Why doesn't Rocket Lab use a solid stage?

I was just reading about the Scout, an all-solid rocket, and thought of Rocket Lab's Electron, which seems to have a similar mission of deploying small payloads to orbit. I understand the engines to ...
2
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1answer
95 views

What kind of methane-fueled rocket engines exist?

I have heard of methane being a strong contender for Mars and beyond. Methane is a cryogenic fuel and is said to have a high specific impulse, and work with closed- and open-expander cycles. I have ...
8
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1answer
266 views

Why don't all SSME turbopumps gimbal with the engine?

The SSME low-pressure pumps (both fuel and oxidizer) are mounted to the vehicle structure and don't gimbal. The high-pressure pumps are gimbaling with the engine, so the propellant lines between low-...
7
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2answers
1k views

Why does the Superdraco exhaust seem so under-expanded in this photo?

The Ars Technica articles From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers Dragon was destroyed just before the firing of its SuperDraco thrusters both include this "file photo" ...
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6answers
8k views

Why aren't air breathing engines used as small first stages?

I am wondering why we don't use jet engines as first stages. Most small rockets, like the Electron, can lift off with a small thrust. In the Electron's case, 192 kN. Why can't we replace the 9 ...
7
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1answer
265 views

Are turbopumps lubricated?

It is easy to find data about rocket engine propellant, but quite difficult to find information about other fluids used in rocket engine. For engine using a turbopump, this pump turns at quite high ...
2
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1answer
95 views

What is the O/F mixture ratio and the ISP for the SuperDraco Engine by SpaceX?

Is it safe to assume a mixture ratio of 2.16 with an ISP of 313 s for the NTO/MMH, SuperDraco Engine manufactured by SpaceX? I am referencing the 2.16 propellant mixture ratio, and estimating or ...
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1answer
172 views

Could this satellite wobble in orbit creating additional orbital angular momentum?

This question asks if this type of steam engine would work: Could a steam Engine outperform other electric producing devices in space? this not a sterling engine since it has far less moving parts. ...
2
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2answers
149 views

Break Away Valves for Launch [duplicate]

I forgot to hang up the fuel pump and broke it off and costed around 80 dollars to replace. While there I wandered could this be adapted to a rocket in some way? How much fuel capacity would be saved ...
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3answers
218 views

How much of the exhaust speed is due to combustion and how much is due to the injection?

The thrust $F$ of a rocket engine is given by $$F=\dot{m}v$$ where $\dot{m}$ is the mass flow and $v$ is the exhaust speed. Now the first factor, $\dot{m}$, is almost entirely due to the turbo pumps (...
0
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1answer
113 views

Could rockets benefit from Reaction Engine's Air-Breathing Rocket Engine in terms of payload?

While I get that one is a vertically launched rocket and the other is a space plane, is it even wildly possible that there could be a vertical intake version of the SABRE engine? Maybe it can be used ...
3
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0answers
211 views

Could a steam Engine outperform other electric producing devices in space? [closed]

What would be the Specific Impulse of a steam-based propulsion system like this model in space? Are there any types of engine that works this way? Could 2 tanks be designed to rotate slowly in space ...
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1answer
80 views

What types of engines are able to go from Earth orbit to Martian orbit? [closed]

What engine is the most efficient in fuel and/or time to go from Earth orbit to Mars orbit and back again that are not capable of launching from the ground?
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1answer
127 views

Is there any combustion chamber and nozzle cooled with liquid oxygen instead of fuel?

There are many rocket engines for liquid propellants which use the fuel (rocket petrol or liquid hydrogen for instance) to cool the walls of the combustion chamber and the nozzle. But are there any ...
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0answers
123 views

Why does Orion's Jettison Motor, have four nozzles but eight Attitude Control Motors arranged in an octagon?

Spaceflight 101's Orion Spacecraft Overview shows the following tests for the escape system. Why are there eight ACS thrusters arranged octagonally? Is it just to reduce cosine losses or does this ...
5
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1answer
222 views

NASA's RS-25 Engines

I am developing a FSX-based space flight simulator FSX SpacePort. I've been trying to get the detailed specs on NASA's RS-25 engine, namely, what were the ramp-up times for this engine? As in, how ...
2
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1answer
130 views

How do you determine what the temperature will be in the combustion chamber of a rocket engine?

I am guessing it is dependent on the fuel and oxidiser and the chamber pressure but is there an equation that would calculate the chamber temperature?
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1answer
44 views

Weight Flow Rate

I read in the book INTRODUCTION TO ROCKET SCIENCE AND ENGINEERING by T.S.T that Rocket Engineers design how big the throat of the nozzle should be based on the Weight Flow Rate. So my question is HOW?
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1answer
165 views

What is a raptor engine manifold and what's happening in these tweeted pics?

When I think of the words "engine manifold" I think of these. I saw this tweet by Elon Musk which shows the image below, and then there is a reply image with a checkerboard pattern behind part of the ...
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2answers
77 views

Relationship between propellant mass and thrust at relativistic speeds

When answering this question about relativity and delta-V I realized I don't know the relationship between the mass of propellants and how much delta-v they would produce in an engine at relativistic ...
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1answer
26 views

How do you read an Engine Throttling specification of 3-5:1 in percent thrust load?

I was looking at the CECE engine by Aerojet, however I am not sure how to determine the trust range of percent thrust range of the engine. How I can translate the throttling spec into a percent load ...
3
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2answers
94 views

Is there an upper stage main engine that is human ratable and may out perform the Common Extensible Cyrogenic Engine performance by Aerojet?

I am fasinated by Aerojet. The CECE, has a total qualified burn time of 10,000 seconds and with a total of 50 restarts. The LOX/LH2 engines have a great performance with a specific impulse of > 445. ...
4
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1answer
120 views

Is a kilowatt per square centimeter a typical launch engine's thermal energy flux (density)?

I saw the following image while searching for this answer in Sung Hwan Kim's thesis Germanium-Source Tunnel Field Effect Transistors for Ultra-Low Power Digital Logic It plots power density in Watts ...
2
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1answer
298 views

Advantage of full-flow staged combustion vs conventional staged combustion engine

Referring to the question in this thread. What is the advantage of full-flow staged combustion (FFSC) vs conventional staged combustion rocket engine? In FFSC we feed the full volume of fuel and ...
2
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1answer
118 views

What's the smallest kerolox engine that is/was used for spaceflight?

This comment linked in this answer to the question How does the camera make the exhaust of the Electron's RP-1/LOX exhaust transparent? says Some quick calculation suggests the thickness of the ...
3
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2answers
183 views

Is presssuized gas absent in a turbopump-driven rocket engines?

For RL-10 rocket engines, are the propellent pumps able to provide the propellent without a source of pressurant gas?
3
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0answers
52 views

What main engine used in a series of environmental satellites has failed more than once (according to the GAO)?

A GAO report on NASA's ongoing projects can be found here. On page 70 while discussing the Lucy mission, it says the ... main engine was the same model used on a series of environmental ...
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1answer
135 views

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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1answer
1k views

Crew Dragon SuperDraco Engine Covers

(Source: Nasa Spaceflight article) While looking at the new images of the upcoming crew dragon launch I noticed a distinct lack of holes in the part of the dragon the Engines are supposed to be in. ...
29
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1answer
4k views

What are the 'lights' inside Shuttle main engines at landing?

I have a night-landing photo of the Shuttle showing lights (I assume some type of glow-plug to burn off extraneous fuel). My understanding is that only the OMS engines burn to begin reentry. Can ...
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0answers
439 views

Why isn't stainless steel used for rocket engines?

Most people have probably heard by now that Elon is changing Starship to a complete stainless steel build. Anyways, it got me thinking, why isn't stainless steel ever used for rocket engines (nozzle, ...
20
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3answers
4k views

Why was the engine of the launch vehicle recently tested in Iran “not a very good missile engine”?

The NPR News item What's Iran Up To With Recent Rocket Launch Attempt? by NPR's Geoff Brumfiel, about a recent launch test in Iran includes the following: Earlier this week, Iran attempted to ...
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1answer
146 views

Why not turn off the main engines while using the launch escape system on liquid fuelled engines?

I've seen a couple of launch escape systems firing and the rockets main engines are on, isn't it more safe if you turn off the engines? Edit: i agree that the engines turning off might be not so ...
3
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1answer
140 views

The changes of a throttled Merlin-1d engine

With Merlin-1d being able to throttle down from its full thrust potential, this post about its throttle capability does not mention much of its change in performance. On the Wikipedia page of Merlin-...
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1answer
176 views

How often has (or how common is it for) the ISS's orbit been propulsive lowered intentionally?

The question Which engine worked the hardest to keep the ISS in orbit? laments the tireless efforts to keep the ISS from falling from the sky by regularly executing propulsive orbit-raising maneuvers. ...
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1answer
1k views

Can a Soyuz-MS still propel itself back to earth if all its Hydrogen Peroxide decomposed?

In this answer it is stated that: If the fuel fully decomposes then return to Earth is still possible but only via ballistic descent I find it a little bit surprising, but maybe there is enough Δv ...
4
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1answer
173 views

Why is the engine configuration of the Mitsubishi H3 rocket designed to be off center?

Here is a diagram from a recent Ars Technica article about the H3: You can see at the bottom that the main engines are not 90 degrees off from the side engines. I'm sure that this has been accounted ...
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0answers
208 views

What is the best fuel for bottle rocket? [closed]

I want to modify my firework bottle rocket to fly a mile high. What will be the best fuel for this? Could fuel used in space rockets be scaled down to work in a large bottle rocket?