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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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1answer
61 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
122 views

How often has 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
124 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
94 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?
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2answers
99 views

What are some notable cold gas thruster propellants, and why?

Cold gas thrusters are a very simple and reliable form of thruster that operate only by spraying a compressed gas, without any chemical reaction. What are the most common, performant, or otherwise ...
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0answers
24 views

Quantitative plots of v, T, p, vs position from chamber through nozzle to ambient for a few canonical modern engines?

In this answer I showed the schematic diagram of a basic de Laval nozzle and representative plots of how temperature, pressure and and velocity would behave. It can be used as a rough representation ...
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1answer
34 views

Achieving relativistic speeds by lasers

Basic data about our spacecraft: Basically were using a laser as an engine. Mass: 1000 Tons Electrical Power for the laser: 10 GW Efficiency of the laser(s) : 50% So first I calculated the kinetic ...
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5answers
4k views

Falcon 9: engines stabilize spin

On CRS-16, the landing Falcon 9 booster entered a spin rotation due to a stalling grid fin hydraulic pump. According to Musk, the engines stabilized the spin. How is this possible? The main engines ...
5
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2answers
252 views

What are these flames on the Falcon 9 booster?

When Falcon 9 was on its way to ascend, flames appeared around the bottom of the booster. What are they? It seems to begin around about 20:36 in the video, ...
3
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1answer
599 views

Have all of InSight's engines/thrusters been permanently disabled now that it has landed?

One aspect of InSight's condition that may be helpful to formulating an answer to the question Could InSight lift off and move somewhere else? is the current status of InSight's propulsion system. ...
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0answers
88 views

What is an “M motor” used in a full-scale model of a Corporal missile?

The NASA JPL video Corporal: America’s First Guided Ballistic Missile shows that it used an Acid/Analine engine. That would have been both challenging and unpleasant to reproduce. So instead, the ...
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0answers
92 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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0answers
64 views

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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3answers
2k views

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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0answers
67 views

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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1answer
907 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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1answer
94 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 ...
6
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1answer
224 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 ...
2
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1answer
200 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 ...
4
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1answer
152 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 ...
3
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1answer
162 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 ...
6
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1answer
228 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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0answers
265 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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0answers
103 views

Was Jules Verne the inventor of the retro-rocket?

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 ...
2
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1answer
96 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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2answers
58 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 ...
6
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1answer
165 views

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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0answers
50 views

Nozzle extension(skirt) attachment mechanism

I am looking for the nozzle skirt attachment mechanism, for RocketLab it looks like nuts and bolts and for SpaceX I don't have any idea. If anybody have any reference for what mechanism should be ...
4
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1answer
132 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, ...
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2answers
90 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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0answers
48 views

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
80 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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1answer
84 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 ...
6
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1answer
155 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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0answers
93 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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1answer
63 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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4answers
210 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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0answers
87 views

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 ...
2
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1answer
56 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
130 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
136 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 ...
4
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1answer
99 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
85 views

Nature of Sabre pre-cooler deminstration 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 ...
6
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1answer
545 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 ...
5
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1answer
237 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 ...
2
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1answer
87 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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2answers
2k views

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 ...
5
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2answers
253 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
125 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 ...