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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".

27
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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
votes
2answers
234 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
votes
1answer
584 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. ...
9
votes
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. ...
0
votes
1answer
92 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 ...
2
votes
1answer
179 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 ...
3
votes
1answer
160 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
votes
1answer
213 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 ...
13
votes
0answers
237 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 ...
8
votes
0answers
100 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
votes
1answer
84 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 ...
2
votes
0answers
45 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 ...
1
vote
1answer
74 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 ...
1
vote
0answers
92 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 ...
1
vote
1answer
62 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 ...
1
vote
0answers
86 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
votes
1answer
55 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 ...
1
vote
1answer
107 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 ...
1
vote
1answer
104 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 ...
2
votes
1answer
79 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
votes
1answer
528 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
votes
1answer
235 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
votes
1answer
74 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?
15
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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
votes
2answers
235 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 ...
5
votes
1answer
115 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 ...
8
votes
2answers
186 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 ...
3
votes
0answers
60 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 ...
4
votes
0answers
36 views

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 ...
5
votes
1answer
180 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 ...
0
votes
0answers
45 views

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 "...
-4
votes
2answers
107 views

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 ...
2
votes
2answers
227 views

Why does air get sucked in for a moment before engine start?

We have commonly observed that before engine start at T minus zero, for a very small moment before the exhaust gases gush out of the nozzle, the air around the nozzle is pulled in. For what reason can ...
5
votes
1answer
254 views

Cost Estimation of Satellite propulsion systems

As part of my research project, i am evaluating various satellite propulsion systems. Are there any databases or forums where the ROM cost of a Satellite propulsion system is listed. A few new space ...
17
votes
3answers
3k views

What engines did (or could) Buran have?

As I learned the primary design difference between Buran and the USA Space Shuttles was that Buran rode a rocket to the orbit passively, while the Shuttles were firing their own engines, riding on ...
6
votes
1answer
619 views

How did SpaceX achieve such a high Thrust to Weight ratio with the Merlin engine?

Were there specific breakthroughs which allowed SpaceX to get such an incredible thrust to weight ratio? The next closest American engine was almost twice as heavy (199 vs 82), and the next closest ...
4
votes
1answer
134 views

Got Milk? Why is the term “colloid” used in “Colloid or Electrospray thruster”?

From this answer to the question "Difference between colloid thrusters and electro spray thrusters" I've extracted the following: According to the Wikipedia article Colloid thruster they are the same ...
3
votes
1answer
183 views

Which engine failed during CRS-1?

During SpaceX's CRS-1 mission, "engine 1" failed, but the booster still completed its primary mission due to a plentiful thrust and fuel margin. Clearly, an outboard engine failure is more critical ...
1
vote
2answers
435 views

What fire will Firefly fly, and when? (update/clarification on planned launch vehicle)

This answer from 2017-Dec-03 says: Firefly Aerospace will use an (annular) aerospike engine with their Alpha rocket. They have a planned launch in 2018. The linked Wikipedia article shows this (...
1
vote
0answers
151 views

How do you calculate total Thrust and Specific Impulse for a rocket stage?

Given the stage has the following configuration: Thrust 741.4 kN (Main) 47.1 kN (Vernier) Specific impulse 297.999 s (Main) 288.999 s (Vernier) How ...
21
votes
4answers
5k views

Why 31 engines for the BFR?

I understand the philosophy of using relatively many smaller engines so that a single engine failure has minimal impact on the mission (provided you can keep the shrapnel from shredding the others) ...
-1
votes
1answer
42 views

Asteroid belt to earth orbit [closed]

Given a constant 1g acceleration with a reaction-less drive how long would it take to achieve zero-zero in earth orbit from the asteroid belt?
4
votes
1answer
174 views

Don't Preburner exhaust fumes disturb the combustion in a Full-flow Staged Engine?

Since Full-Flow Staged Engine uses preburned fuel/OX-rich gases in combustion chamber, don't those exhaust fumes produced by the preburner somehow unbalance or 'pollute' the pure combustion of fuel ...
9
votes
2answers
2k views

What do rockets eject?

So for instance, for the space shuttle,liquid hydrogen will react with liquid oxygen to produce water vapour. Is only water vapour ejected from the rocket? Or will the ejected mass be a mix of water ...
5
votes
0answers
104 views

How will GomX-4B manage angular momentum when using butane thrusters to move?

Phys.org's ESA's next satellite propelled by butane describes GomX-4B's butane powered cold gas thrusters, and how it will test them and use them to navigate to different distances from its partner ...
4
votes
1answer
222 views

Apollo 6, reason for prematurely engine shutdown of two engines of second stage of Saturn V?

I found different versions in the english and german Wikipedia articles about the Apollo 6 flight. "Das zweite Triebwerk wurde vom Steuerungssystem fälschlicherweise deaktiviert, weil die ...
12
votes
1answer
2k views

How do Voyager 1's Trajectory Control Thrusters differ from its Attitude Control Thrusters?

There are several popular news items about the recent test of Voyager 1's Trajectory Control Thrusters to see if they can be used for attitude control to facilitate communication with Earth. The ...
5
votes
1answer
304 views

Do Falcon 9 preflight static fire ignitions use up the engines' ignitors?

After a Falcon 9 has its static fire several days prior to the actual launch, are the TEA-TEB ignitors inside the engine replenished? Or do they have enough to ignite the engines for the static fire ...
8
votes
1answer
1k views

What are the advantages of Ox-rich staged combustion?

In the context of staged combustion, I understand that burning ox-rich creates complications associated with having hot, high pressure, oxidizer. Some engines, notably the RD-170 and RD-180 family run ...
0
votes
0answers
58 views

What is the mechanism principle of the grid fins in F9? [duplicate]

What is the mechanism principle of the grid fins in F9? or how to design the mechanism for the electricity grid fins? or how to design a electricity folding wing like the grid fins in F9?