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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11
votes
1answer
4k 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? ...
33
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7answers
16k 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 ...
6
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1answer
1k views

Why do Proton rockets use two types of main engines in its second stage?

The second stage of Proton (8K-82K) rocket has two types of main engines (RD-0210 and RD-0211). Does someone knows why?
14
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4answers
4k views

Is LMP-103S truly a viable replacement for Hydrazine?

LMP-103S is the name of a new monopropellant, tested on the PRISMA mission in 2010. It's main ingredient is ADN (Ammonium Dinitramide), a strange chemical invented in the 70's in USSR and ...
9
votes
1answer
1k views

How is blow-back prevented in monopropellant chemical rockets?

Let's say we have a monopropellant, pressure-fed rocket engine. We don't want the combustion in the chamber to propagate back up the fuel line and into the fuel tank or we will have a big kaboom. (...
6
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2answers
4k views

Does the second stage of the Falcon 9 have RCS thrusters?

This video (a tour of the SpaceX factory by Elon Musk) suggests that the second stage of Falcon 9 has Draco thrusters as a Reaction Control System (RCS) (at 2:14), but I don't recall ever seeing them ...
19
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3answers
20k views

What are the differences between a standard Merlin engine and the Merlin Vacuum engine?

I know that there's a difference between SpaceX's Falcon 9 1st stage engines and the 2nd stage engine, since that stage is specifically tuned for vacuum. Wikipedia also says that the Merlin Vacuum ...
10
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3answers
2k views

If the Alcubierre Warp Drive was used to travel to Alpha Centauri, how much time would pass on Earth?

If the Alcubierre Warp Drive was used to travel to Alpha Centauri, how much time would pass on Earth? Per this article, it would take merely days to travel there. Say a ship travels there, spends a ...
6
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1answer
1k views

What auxiliary engines do the Falcon 9 first stage have?

Looking at the launches and animations for the Falcon 9, you can clearly see some rockets firing at the top/side of the stage to maneuver it clear of the second stage and orient it correctly for ...
29
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3answers
8k 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 ...
8
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1answer
982 views

Why does the Dawn spacecraft have three ion engines at different angles?

The Dawn spacecraft has three ion engines that are mounted such that their thrust vectors are at significant angles. You can see this in this image: In the image, one of the three engines is active. ...
4
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0answers
660 views

If the J-2X is too powerful for SLS, why was it appropriate for Saturn V?

Reading an article about new engines for the SLS (Summary: There is no plan what to do once the current SSME's are expended), they mention that the J-2X is too powerful for the upper stage of SLS. ...
5
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1answer
352 views

What was RD-180 used in, before Atlas III/V?

At NasaSpaceFlight.com, Chris Gerbhart writes: The RD-180 has provided exceptional performance to the Atlas V and was chosen to be the engine of the first stage in no small part because of its ...
37
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3answers
12k 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 ...
1
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0answers
286 views

Pintle injector in a Vortex Cooled Chamber Wall (VCCW) Engine

All the articles I have found show the VCCW engines using flat plate injectors. With the inherent combustion stability of a Pintle injector system, it would seem to be a better choice, yet I find no ...
8
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4answers
2k views

Russian manned Moon landing capability today

Do Russians have means of launching a manned mission to the Moon? Do they have an engine with sufficient thrust and stability needed (RD-170 has bigger thrust than the F-1 engine, if I read the data ...
13
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5answers
3k views

Other than then N-1 (30 engines) has there been a single stage of a rocket with more engines than a Falcon 9?

The Saturn V had 5 engines (F-1) on the first stage, five engines on the second stage (J-2). The N-1 had 30 engines on its first stage (NK-15). The Falcon 9 (1.0 and 1.1) have 9 Merlin 1 engines on ...
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 ...
10
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3answers
7k views

How does liquified natural gas compare to liquid methane?

So ULA and Blue Origin have announced they are designing a LOX/LNG rocket engine (link). From what I understand, LNG is just a less pure form of methane (CH4). Is this correct? Why are they ...
3
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1answer
359 views

ISRO's Mars Orbiter Mission - LAM vs Attitude thrusters reliability

ISRO expressed concerns on restarting the Liquid Apogee Motor (LAM) for Mars Orbit Insertion (MOI) after a long coasting period of its Mars Orbiter Mission (MOM). ISRO has redesigned the LAM plumbing ...
18
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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?
5
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1answer
1k views

How could a spacecraft be continuously propelled if it rotates to simulate gravity (by tether)?

For long term crewed space travel, gravity might be simulated by rotating a habitat in a long tether to a counter weight. Conventional chemical rocket engines give a spacecraft a brief initial impulse....
6
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2answers
464 views

Was the notion of using an air-started SSME on Ares-1 a reasonable idea?

For whatever reasons, it seems like the standard upper stage engine in the U.S. inventory is the RL-10. A high performance engine with nice specific impulse (Isp = 450-465 s), but very low thrust (25 ...
2
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1answer
2k views

What are the costs of the various different engines in current use?

This may be impossible to answer, since the data is often not disclosed. But in an article, about ULA getting RD-180's from Russia it claims: Each engine reportedly costs between \$11 to \$15 ...
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3answers
1k views

What replacement engine options are there for Antares?

Lots of articles out about how Orbital Sciences is talking with three vendors for a replacement for the NK-33/AJ26 engine pair currently used on the Antares booster. An article on SpaceNews notes ...
20
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1answer
584 views

Does the proximity of engines in engine clusters cause interference?

One way to create a heavy launch vehicle is by clustering large numbers of small engines together in a stage. An example of this approach is the SpaceX Falcon 9: Now I've heard people arguing against ...
7
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1answer
448 views

Have the micronewton thrusters developed for the LISA mission been flight tested yet?

JPL together with Goddard and a private company called Busek Company Inc. developed a new type of propulsion system known as micronewton thrusters for the LISA mission (which has since had a name ...
9
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2answers
2k views

What is a dual-combustion chamber design?

Apropos the RD-180, Wikipedia writes to say It features a dual-combustion chamber, dual-nozzle design and is fueled by a kerosene/liquid oxygen mixture What is a dual-combustion chamber design? ...
5
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1answer
176 views

Is there a good chart, comparing the various Russian engines proposed for Soyuz (Booster) upgrades?

There are so many proposed Soyuz booster upgrades, I cannot keep them straight. I was wondering if there is a good comparison chart between the various proposed upgrades, including engine information....
21
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1answer
7k views

How does SpaceX ignite their engines?

Based on the aborted launch on Thanksgiving 2013 of the first Falcon 9 v1.1 from Florida, we know that an issue occurred where oxygen got into the ground based TEA-TEB sources. I understand that TEA-...
30
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5answers
19k views

Why does a rocket engine provide more thrust in a vacuum than in atmosphere?

According to NASA Each Space Shuttle Main Engine operates at a liquid oxygen/liquid hydrogen mixture ratio of 6 to 1 to produce a sea level thrust of 179,097 kilograms (375,000 pounds) and ...
15
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1answer
3k 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 ...
33
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3answers
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?
8
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1answer
479 views

How will the RD-180 ban affect US space program?

RD-180 is a rocket engine produced by Russian NPO Energomash company. It is used in such US rockets as Atlas III and Atlas V. There are rumors, that Russia is considering to ban RD-180 export to US. ...
14
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4answers
3k views

Why do pump and pressure fed liquid engines need to operate at high pressures?

There is apparently some confusion as to why pump or pressure fed liquid rocket engines need to operate at high pressure to product significant thrust, based on the comments to this question about ...

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