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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176 views

How are Voyager's 16 thrusters oriented?

@RussellBorogove's excellent answer to the question How do Voyager 1's Trajectory Control Thrusters differ from its Attitude Control Thrusters? describes the locations and usage patterns of the 16 ...
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Problems with shutting off “torch igniter” during the operation of combustion chamber

With reference to the presentation pp 76, where SSME's Augmented Spark Igniter is said to have their flame "On" even after the main combustion chamber ignition, is to prevent the blowback from the ...
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Why do chemical rockets encompass a weird shape on this thrust vs. Isp graph?

Consider this graph of engine thrust versus specific impulse (from https://dawn.jpl.nasa.gov/mission/ion_prop.html): Most propulsion technologies encompass roughly rectangular regions on the graph. ...
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Purging process of a rocket engine

Does spacex purge Falcon 9 engines after landing ? If so, which gas is used for purging?
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2k views

Why is a purging process necessary for static firing test of liquid rocket engines?

In Chapter 7 of Modern Engineering for Design of Liquid propellant Rocket Engines by Huzel and Huang, mentions the following engine cut off procedure. The cutoff sequence usually consists of ...
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122 views

Has the use of any commercial launch vehicle's engines on an unrelated vehicle ever been seriously considered?

When reading On the Cusp: What’s NextDARPA Perspective on Space Briefing prepared for 53rd Robert H. Goddard Memorial Symposium March 12, 2015 I saw the slide shown below. The slide's heading is ...
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1answer
495 views

How does falcon-9 engine survive while re-entry burn without chilling ?

I've often seen that in launch sequence, "engine chilldown". I've learnt that chilling is done to avoid thermal cracking in plumbing lines and also to avoid cavitation. While re-entry, do they ...
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1answer
1k views

What is the highest gimbal range ever used on an engine?

This answer here mentions the STS-94's ability to gimbal up to 20 degrees in all directions, that got me thinking, what exactly is the maximum ever feasibly implemented? I've seen a lot of information ...
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305 views

How are rocket propellants ignited repeatedly without the ignition source melting

I know that SpaceX's Falcon uses TEA-TEB instead of a physical igniter, but if I remember correctly, NASA has never used hypergolic propellants to start their restart-able engines. How does NASA's (or ...
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1answer
211 views

What is the inner wall of the thrust chamber made of?

With advancements in additive manufacturing, the manufacture of regeneratively cooled thrust chambers is simpler nowadays. Brooklyn based startup Launcher Space Inc. says most 3D printed engines use ...
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543 views

Why are 22N and 440N liquid engines quite common?

One can often spot that liquid apogee engines are 440 N and attitude control systems are 22 N. Is there a reason why the thrusts are proportional? If the engines are scaled for reducing development ...
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691 views

Why is the exhaust plume of Falcon 9 upper stage shaped the way it is?

The (single) Merlin 1D vacuum engine's exhaust plume has a symmetric shape, comprising of six distinct "inner" plumes. Why does it have this shape? Is it due to the shape/configuration of fuel ...
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464 views

Was Jules Verne the first to propose the retro-rocket concept?

In his novels 'From the Earth to the Moon', and 'Around the Moon', Jules Verne writes about a set of rockets fitted to the spacecraft he imagined, that were intended to be fired in order to slow down ...
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268 views

How large is a magnetoplasmadynamic (MPD) thruster? Are there any upcoming programs using it?

Magnetoplasmadynamic thrusters are an interesting proposed method for propulsion in space, but are there any upcoming programs that will use them? If not, might this be because there still serious and ...
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143 views

Where can I read further on the specs the South Korean engine for next month's sub-orbital test?

Ars Technica's weekly installment of Rocket Report: SpaceX gets Moon launches, South Korean rocket, BE-4 wins says: South Korea to test first-stage engine. The Korea Aerospace Research Institute says ...
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What may be the condition of the first stages of Saturn V splashed into ocean after separation?

Two F-1 engines were recovered from a depth of 14,000 feet (4,300 m), about 400 miles (640 km) east of Cape Canaveral after 40 years in the ocean. There is much damage caused by splash down but very ...
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242 views

How common is the ability to compensate for a lost engine through gimbaling?

Discussing a system of regulating thrust through lighting/extinguishing engine pairs, I was met with a reply: Really there is no need to treat engines as a pair in this context. In fact, beyond ...
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315 views

Galilean cannon

Do you think that Galilean Cannon can be somehow useful in rocket industry during space exploration, example to launch rocket from the Earth or from the orbit to far space? The mass of ball might be ...
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How to overcome the challenge of igniting kerosene using spark plugs?

Discussions in this question and its answer, concerning the use of spark plug ignition for Kero/GOx system outlines the energy limitations of spark plugs to ignite the mixture. But Ignition Transient ...
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1answer
450 views

Does kerosene get ignited by a spark plug? [duplicate]

Are spark plugs used in kero-LOx engine(say J1 engines)? If so, then there are two major issues when using spark plug to ignite kerosene. Wetting of the spark plug causes spark to be smaller and the ...
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112 views

What parameters of an rocket engine determines whether it is fit for any more static hot fire test?

Typically engines built are repeatedly hot fired to analyses their performance. In between tests, what are the review that the engine undergoes? How is an engine gauged suitable for a hot fire ...
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267 views

Why do some engines have so many little tubes, and others, not so much?

This comment about the Houston Space Center's Rocket Garden drew my attention to the cropped image below, from that link. I'm under the impression that some liquid propellant engines don't have a ...
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1answer
251 views

F1 engine specification?

I am collecting the engine specification data of different engines. I want to know the nozzle length and combustion chamber length and diameter of the F1 engine of Saturn-5. Please give some ...
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117 views

Does an engine's Isp rating always include all mass flow rates, including those for electrical or mechanical power generations?

Discussions here have convinced me to ask this separately. Isp or mass-specific impulse is a ratio of thrust (force) to mass flow rate (kg/s). It comes in two flavors, seconds and meters/second ...
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2k views

In the context of calculating mass flow rate from thrust and Isp, how would an additional efficiency be defined?

In this answer I show a quickie derivation for calculating a mass flow rate of a rocket from a known thrust and Isp. A comment there says: That assumes 100% efficiency and ignores the fuel ...
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Detaching parts of engine bell

I was looking at engine bells, and I was wondering: would it be possible or useful for a diamond shaped engine bell, that would stage sections off, creating a wider bell as the rocket leaves the ...
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105 views

What is intermediate thrust and brief pause for checkout on launching Soyuz spacecraft?

In a book I'm reading, the author mentioned the launch of Soyuz spacecraft as follows: What made it more spectacular was how close we were when it lifted off the launch pad. Yuri, Tim and I were ...
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1answer
552 views

How long does Augmented Spark Igniter fire?

The heroicrelics.org page J-2 Rocket Engine Augmented Spark Igniter mentions that The ASI operates continuously during entire engine firing Does this how all spark igniters function in rocket ...
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1answer
815 views

How is a spark plug igniter of rocket different from one used in IC engines?

US20120103302 shows a spark ignited prechamber combustion system typically used for IC engines. It basically consists of a chamber which has a input of premixed fuel-air mixture and a spark plug to ...
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2answers
233 views

What happens in to the fuel in fuel-rich Lox-Kerosene?

This link Optimum Mixture Ratio shows a range of mixture ratios for Lox-Kerosene of 2.1 to 2.45. Its not clear to me where in this range is the stochiometric case. Some Russian designs are higher (RD-...
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1answer
231 views

Nature of Sabre pre-cooler demonstration test

Inspired by a comment to this question "How does the Sabre engine's pre-cooler achieve such high performance?": the comment was that Reaction Engines have demonstrated that the pre-cooler works on ...
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1answer
949 views

What is the minimal TWR of Falcon 9 booster right before touchdown?

A big point about Falcon 9 booster landing is that they need to stick the landing on the first try; they can't just hover and adjust position because even fully throttled single Merlin engine provides ...
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1answer
528 views

Which is the preferred mode of liquid rocket engine cutoff - fuel lean cutoff or fuel rich cutoff?

When a bi-propellant liquid rocket engine receives a command to shut down, will the fuel gets cut off first and then the oxidiser - a fuel lean cutoff? Will the oxidiser gets cut off first and then ...
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223 views

Materials used for turbopump construction for LOX

What are the materials used in the Rocketdyne F-1 engine's turbopump design and what was the pressure rise?
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How exactly is the pressure inside the combustion chamber monitored?

Given that temperatures in the combustion chamber are crazy high, are there any pressure sensors rated for the high temperature and high pressures located there? Or is there a cooling mechanism for ...
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1k views

What is the purpose of the “shaft” and “block” in these two different engine gimbal joints?

This question refers to the device which transfers the thrust force from the engine to the vehicle while allowing the engine to swivel - the "gimbal joint". Both the F-1 and SSME have a bolt- or ...
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1answer
248 views

Is there a way to make liquid fueled rockets not lose efficiency with decreasing throttle?

As far as I know liquid fueled rockets suffer from lowered efficiency when using less than full throttle since the pressure of combustion is lowered and so thermodynamic efficiency. Could a variable ...
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2answers
351 views

With pressure-fed engines, is any measurable thrust generated by venting the pressurant out the engine bell after flameout?

A pressure-fed rocket engine supplies fuel and oxidiser to the combustion chamber by pressurising the fuel and oxidiser tanks with an inert gas (typically helium or nitrogen). Presumably, when a ...
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179 views

Rocket engine propellant/cycle combinations

I am trying to determine typical relationships between engine mass and performance for various types of engines, so I'm looking for a broad spectrum of examples to extrapolate from. I'm segregating ...
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321 views

Planned usage of F-1 rocket engine in 1955?

The F-1 engine used for the first stage of the Saturn V is still the most powerful liquid fuel rocket engine. The development of the F-1 was started very early in 1955 by the US Air Force. In 1958 the ...
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949 views

Red color in the nozzles of Soyuz-2 rocket engines RD-107 and RD-108, is it only a decoration?

Many pictures of the Soyuz-2 show the inside of the nozzles painted with a brilliant red. Is there any function of the paint during ignition and operation of the rocket engines, or is it just a ...
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329 views

SSME propellant duct routing

The low pressure propellant ducts in SSME are routed around the engine in a somewhat complicated way. Both fuel and oxidizer lines leave the low-pressure turbopump, go around, down and then turn back ...
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Have any vehicles used asymmetrically variable thrust for active stabilisation? [duplicate]

Have there been any tests or attempts at developing a propulsion system that uses variable thrust for attitude control (particularly during launch)? Conventional systems often use fully gimballed ...
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1answer
549 views

Nozzle material of Apollo Lunar Module ascent engine?

There are some photos of the Apollo Lunar Module ascent engine, see 1, 2, 3. The nozzle looks like being made of epoxy and fiberglass. The fibers are wound in two different directions. Is it true ...
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2k views

What do we mean by rocket stages?

I'am new in the field of rocketing and space,i wanted to know what do we do by adding different stages to a rocket and it's used for what, and if we add a second stage we can put another booster on it ...
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1answer
863 views

What would be the performance of a nuclear lightbulb engine with graphene instead of quartz?

The nuclear lightbulb is a closed-cycle gas-core nuclear propulsion system. It uses quartz to separate the nuclear fuel from the propellent, thus eliminating the radiation problems with open-core ...
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How do you calculate what percent of hydrogen combustion is turned into heat vs pressure?

As a high school calculus and physics student interested in aerospace engineering, I was trying to understand the basics of how a rocket works and couldn’t find an equation or any analysis online on ...
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Is spacecraft propulsion observable in space? [duplicate]

There are questions on this site about minimal sound in space. But I was very surprised by Russell Borogove's answer to "Why did the Saturn V stage faring appear to burn after separation?" that "...
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252 views

In ion engines, how is energy removed from the electric field that is used to accelerate the particles?

A basic ion engine uses a positively charged plate and passes positively charged ions over it to accelerate them. How does the charged plate draw current to accelerate the ions? It seems that a ...
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Can bad satellites be pulled out of orbit with an Orbital Mass Accelerator? [closed]

Could an Orbital Mass Accelerator OMA be used to knock other satellites out of orbit? Leaping from satellite to satellite using a magnetic field to accelerate some useless satellites and decelerate ...

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