Questions tagged [engine-design]
Questions regarding the design or design process for a propulsion system.
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Could a chemically propelled craft travel directly between Earth and Mars spaceports?
If in the near future we manage to build out some infrastructure in space--including robotic asteroid mining so that we can get water without pushing it up a gravity well--are LOX/LH2 rockets powerful ...
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1answer
107 views
What performance specification would be lower for Krypton than for Xenon in Hall effect thrusters?
The Ars Technica article SpaceX scrubs first attempt to launch 60 Internet satellites [Updated] (found here) discusses the use of Krypton rather than Xenon in the Starlink Hall effect ion thrusters:
...
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0answers
51 views
Why did the nozzles on the SRB's igniter initiator point toward the grain of the main igniter while the main igniter's nozzle pointed straight down?
How did the shuttle designers make those decisions? What made it a better decision to point the exhaust of the igniter initiator toward the main igniter's grain at an angle? What made it a better ...
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0answers
43 views
Does engine purging cause dry run of turbo pump in a liquid rocket engine? If it occurs, what is the implication?
Does engine purging in a liquid rocket engine cause dry run of the turbopump? If so, does that have any implication for the design, health, maintenance, or operation of the pump?
How do we calculate ...
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0answers
236 views
Why is SpaceX's Raptor's design so simple in comparison to SSME?
What is especially striking to me is how simple Raptor is in configuration compared to SSME.
The Raptor doesn't have an LP fuel or oxygen pump. What's even more surprising, if we are to compare the ...
5
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0answers
96 views
Why don't all SSME turbopumps gimbal with the engine?
The SSME low-pressure pumps (both fuel and oxidizer) are mounted to the vehicle structure and don't gimbal. The high-pressure pumps are gimbaling with the engine, so the propellant lines between low-...
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1answer
50 views
Could a solar panel be modified to also collect a static charge on Mars?
I was waiting for someone to piece both of these questions together into another question. @Dragongeek was the first, Could a solar panel be modified to create a static charge while spinning to remove ...
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9answers
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Would a grinding machine be a simple and workable propulsion system for an interplanetary spacecraft?
I am wondering if any space agency has ever considered using a grinding machine as a propulsion system for an interplanetary spacecraft. This system would not be used to lift the spacecraft off of a ...
2
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0answers
58 views
How is this engine put together? [duplicate]
I'm going through How to DESIGN, BUILD and TEST SMALL LIQUID-FUEL ROCKET ENGINES and am confused how their sample engine is physically built together.
This is a picture of their assembly where the ...
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0answers
180 views
Orbit to Orbit Transport Stage
Would it be faster or cheaper to have a lander, SSTO, and/or Space X Mars rocket to rendezvous connect with a more efficient engine or "transport stage" or another lander, SSTO?
When the spacecraft ...
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1answer
73 views
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
109 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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137 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
84 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
1k views
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 ...
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0answers
35 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 ...
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0answers
103 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
55 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
165 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
376 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
32 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
174 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
95 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 ...
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2answers
129 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 ...
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1answer
39 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
55 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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1answer
190 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
81 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
123 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
353 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
86 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 ...
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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?
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2answers
252 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 ...
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1answer
83 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 ...
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0answers
244 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?
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1answer
310 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
295 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
339 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
203 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 ...
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1answer
401 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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2answers
127 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
79 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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0answers
164 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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61 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
143 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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2answers
238 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 ...
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1answer
92 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
169 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
170 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
74 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 ...
