Questions tagged [engine-design]
Questions regarding the design or design process for a propulsion system.
205 questions
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Earth to Mars Booster and Orbiter
Is there any practicality in having an Earth to Mars Orbiter with an extra engine to connect with spacecraft in LEO to and provide thrust from other engines not capable of launch?
starwars.fandom....
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1answer
52 views
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Maximum size for a Ion thruster solar array
In other questions I have asked about using a solar sail to double as a reflective mirror to provide light to an ion engine.
What would be the maximum size or surface area of a parabolic sail where ...
2
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1answer
89 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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87 views
Rao contour nozzle: Calculate throat and exit angle?
The Rao nozzle formula is an empiric formula for a parabolic nozzle used in pretty much all nozzles today.
The problem is it depends on the throat and exit-angle of the nozzle, which varies with ...
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1answer
73 views
Why did the S5.2/9D21 rocket engine engine have pyrocharges?
In a recent question, an answer showed a diagram of a Soviet S5.2/9D21 rocket engine. According to the diagram, there are four pyrocharges (3, 7, 24, and 27) in the engine. What is the purpose/...
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5answers
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Could rockets launched from the ground use wings in the stages?
Could a slower or smaller rocket take advantage of lift if all the stages had wings?
Could the stages reduce splashdown impact forces by using a spinning seedpod-like design (as shown in the image ...
2
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0answers
33 views
What are some common exit pressures for liquid propellant engines?
Most engines are overexpanded at launch so that they reach peak efficiency at altitude. It’s easy to find values for thrust, specific impulse, expansion ratio, chamber pressure, etc, but I’m trying to ...
3
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0answers
76 views
What modifications constituted the ‘reorificing’ of F-1 engines on later Saturn V flights?
The topic of uprating the Saturn V’s first stage engines appears to have been widely discussed, and yet there is little agreement as to how it was done.
Early Rocketdyne F-1 engines quote lower ...
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1answer
52 views
Shape Memory Metal Self Stablizing Solar Sail
Can the frame of a solar sail be made with shape-memory metals to contract in a way to maintain orientation to the Sun either in orbit or interplanetary? Would there be enough temperature difference ...
4
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1answer
142 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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2answers
338 views
How does the speed and volume of particles differ in producing thrust in space?
Does a slower detonation velocity push a ship more the same way explosives with a slower detonation velocity moves dirt better?
At the same rate does slower particles produce more thrust from a ...
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0answers
29 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 ...
6
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1answer
165 views
Why did the MarCO space probes use fire extinguishant as their propellant?
In many news articles, it's mentioned that the MarCO spacecraft, launched with InSight, used fire extinguishant as the propellant for its cold gas thrusters. I originally assumed that this was ...
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1answer
88 views
Is there enough energy in a rocket nozzle for fission?
How much more energy does the rocket exhaust atom have to have to be before fission can occur to create more thrust? Which exhaust byproduct atom would be the easiest to split?
I understand in ...
2
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2answers
120 views
Solid hydrogen hybrid motor engine for launch?
Would hydrogen unlike water in a solid state take less space or be more stable? How would a rocket work using a block of melting solid hydrogen instead of liquid hydrogen? Has and could any kind of ...
1
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1answer
37 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 ...
4
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0answers
52 views
Why doesn't a regeneratively cooled engine crack due to differential expansion induced by thermal gradients?
A liquid rocket engine with regeneratively cooled chamber walls and nozzles would definitely be one among those components experiencing the steepest thermal gradients (Chamber wall inner - $3000 K$ ...
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0answers
102 views
Would a self-winding watch work in space without gravity?
Could a watch that winds itself with a pendulum work in space with no gravity? Could a pendulum or the self winding part be modified to work off the movements of the wrist in a microgravity ...
2
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0answers
78 views
Layout of regenerative cooling tubing?
In F1, and space shuttle engines (I think), the regenerative cooling tubing goes through the inner wall of the nozzle. The russian engines (RD-180 and likes) seem to have smooth inner and outer ...
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0answers
104 views
Does Rocket Lab's Rutherford have margin for uprating with improved battery technology?
We've seen with SpaceX's Merlin engines that the initial design had a lot of headroom for subsequent increases in chamber pressure and mass flow rate (from supercooling and densification) to gain ...
5
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1answer
185 views
Why is Adiabatic wall temperature taken as the driving temperature in rocket engines?
Going by the definition of convective heat transfer coefficient from Wikipedia (which I have started to doubt; reason follows):
$h=\frac{q}{\Delta T}$, where the $\Delta T$ is taken as the difference ...
4
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1answer
76 views
What's the actual oxidizer/fuel ratio in the combustion chamber of the Vulcain?
I'm working on a simple exercise on the Vulcain, but I'm having a hard time figuring out what the real O/F ratio is, in the combustion chamber. I need the mixture ratio in the chamber to calculate the ...
17
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2answers
1k views
How do you confirm ignition in the combustion chamber of a rocket?
Is ignition confirmed using a temperature sensor, pressure sensor or another device?
2
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2answers
176 views
Is the Pulse detonation engine feasible
Now this is a big question and we'll need to fix it and make it more specific but I don't know how .
I recently started reading up on alternative concepts and one that was talked about was pulse ...
2
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1answer
72 views
What advances are there in heat-resistant materials for engines?
As one of the difficulties in engine design is to prevent it from melting, one can expect research to be conducted on what materials to use for thrust chamber and nozzle.
Many engines seem to use ...
3
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0answers
194 views
What is meant by chamber pressure in rocket engines?
Is "chamber pressure" the pressure at the tip of the injector, or the pressure before combustion inside the chamber, or the pressure after combustion inside the chamber?
2
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1answer
255 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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1answer
272 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 ...
3
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1answer
294 views
How do you shut off a Merlin-like rocket engine quickly? How quickly can it be done?
After about 36:17 in part 1 of this recording of SpaceX's Hans Koenigsmann's talk at IAC 2018, he narrates the propulsive landing of a Falcon 9 first stage, and ...
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2answers
176 views
Challenges of using propyne (aka methylacetylene) as rocket fuel
Propyne is a light hydrocarbon which packs quite a lot of energy in a triple carbon bound. It poses no significant health or explosion hazard by itself, and some European studies have found it to be a ...
5
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1answer
283 views
How are the combustion chamber length and diameter decided
How are the combustion chamber length and diameter decided?
Are there any proper formulations or procedures?
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0answers
45 views
Liquid propellant stored as solid
Some propellants have wildly different melting points. The most extreme case is the theoretically fantastic (and nightmarish in practice) Fluorine-Lithium-Hydrogen tripropellant, with liquid hydrogen ...
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2answers
70 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 ...
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149 views
Why is Rocketlabs having lengthy combustion chamber?
Looking at different rocket engines, L/D(CC_length/CC_diameter) ratio of combustion chamber is very much less compared to Rocket labs. Even the modern age engines like Merlin 1d and Raptor engines ...
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55 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
123 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 ...
3
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2answers
212 views
Do some solid rockets burn faster at the bottom? What's an extreme case?
Discussion in comments below this answer relate to how much solid rockets or SRBs burn bottom-to-top versus radially outward.
I am sure I've seen a diagram somewhere showing that different designs ...
6
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1answer
91 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
163 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 ...
10
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1answer
168 views
When regenerative cooling is used, how is the nonuniform radius of the combustion chamber handled?
As the combustion chamber necks down and flares out, the 1-D cross section past which which fuel must pass as it cools the wall of the chamber will change. If there are lots of tubes, they will bunch ...
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1answer
70 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
338 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 ...
2
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0answers
62 views
Is it undesirable for LOx to splash on the walls of combustion chamber?
Typically, there are annular ports on the injector plate to introduce fuel to cool the combustion chamber. Why is LOx not used for cooling despite it being extremely cold?
Given there will be a lot ...
14
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5answers
4k views
Have Air-breathing Engines ever been used on a reentry vehicle, could they be?
For the purpose of this question I would like to assume there is no risk of life for the astronauts, or that the design would only be used for delivery of a non-ethically-sensitive payload. Looking at ...
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2answers
2k views
What kind of antimatter engine is this?
I found this diagram while looking up diamagnetic machines. Could anyone explain what engine this is?
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0answers
88 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 ...
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2answers
115 views
How would the rocket differ in a higher atmospheric or ambient pressure?
I imagine the both rocket nozzles in either environment underwater or Jupiter or underground would have to be different than that of standard rocket nozzles because of the back pressure.
In this ...
3
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3answers
260 views
At what size does a bigger solar sail stop increasing your acceleration?
Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce?
Can a solar sail be added to an ion engine and work better?
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1answer
170 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
199 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 ...
