Questions tagged [engine-design]
Questions regarding the design or design process for a propulsion system.
226
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1answer
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Why can't an expander-cycle engine be built to use RP-1 or other non-cryogenic fuels?
The expander cycle family of rocket-engine power cycles involve using waste heat from the engine's combustion chamber and/or nozzle to vapourise some or all of the engine's fuel, and using the now-...
0
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1answer
55 views
Could LNG fuel be used to pressure feed itself into combustion chamber?
In pressure fed cycle a high pressure gas tank contents are exhausted into the fuel and oxidizer tanks to essentially push them into the combustion chamber.
Could a portion of the fuel from an LNG ...
8
votes
1answer
466 views
What is the job of the acoustic cavities inside the main combustion chamber?
I am new to rocket engines. I was looking at an image of RS-25 engine's MCC and found these acoustic cavities, and I want to know how they work. Can somebody please explain their working principle? ...
1
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1answer
143 views
Could a CubeSat be propelled by this low-tech electromagnetic propulsion system?
I have come up with a conceptual idea for a low-tech electromagnetic propulsion system for a CubeSat, and I would like to know if it would create (on a theoretical basis) a net force strong enough to ...
1
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0answers
28 views
Would a nuclear turbojet with a chemical afterburner be a suitable intermediate between a pure nuclear turbojet and a nuclear thermal rocket?
NOTE: This is not the place to question the fundamental veracity of nuclear propulsion in aircraft and spacecraft.
For context, in a spaceplane, the higher speeds you can attain under air-breathing ...
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1answer
62 views
Was the Titan SRM thrust vs time curve engineered to allow for acceleration switches to initiate staging sequence events?
This answer describes the timing between the Titan III Stage 0 (SRM's) and Stage 1 events.
The Titan first stage ignited just prior to SRM separation:
Titan Stage I ignition occurs at ...
5
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2answers
104 views
Does adding a nozzle increase peak pressure in a rocket?
If I had two charges of the same solid propellant both in the same geometry and casing, and added a de laval nozzle to one, while the other would have just a simple hole for an exhaust, upon firing, ...
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0answers
42 views
Exit pressure for Rocket Lab Curie engine
What do you think the exit pressure for rocket lab curie engine could be?and the area ratio as well? its a kickstage engine and it is said that it has about 25lbf thrust.
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1answer
46 views
Exit pressure value for vacuum nozzle [duplicate]
What value of exit pressure should I use in the design equations for a small liquid rocket engine nozzle for 200km-500km operating conditions?
Since using zero as a value is not possible or else ...
5
votes
1answer
93 views
What is the requirement of spacer rings in solid rocket motors in sounding rockets?
I saw this report SOLID ROCKET MOTOR DESIGN L-CLASS, here as shown in FIGURE-8, they have charged the motor with grain segments with spacer rings in between. Can`t we charge the motor without any ...
8
votes
1answer
232 views
Why is multi-spool pump very rare on rockets?
The only one I know of is the LP LOX pump on RD-0120. A multi-spool design is already a default for jet engines, which are basically turbine-driven air pumps. A multi-spool pump can save at least the ...
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1answer
88 views
What Constitutes A Combustion Chamber?
I have been reading about combustion chambers and noticed they seem to just be an empty space with the fuel and oxidizer coming in one end and the nozzle at the other end.
If the shape below were ...
4
votes
1answer
178 views
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 ...
1
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2answers
390 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:
...
2
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0answers
64 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 ...
3
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0answers
50 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 ...
7
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0answers
286 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 ...
8
votes
1answer
266 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-...
0
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1answer
58 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 ...
25
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9answers
6k views
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
votes
0answers
60 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
193 views
Orbit to Orbit Transport Stage
Would it be faster or cheaper to have a lander, SSTO, and/or SpaceX Mars rocket to rendezvous connect with a more efficient engine or "transport stage" or another lander, SSTO?
When the spacecraft ...
1
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1answer
76 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
votes
1answer
130 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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0answers
185 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 ...
1
vote
1answer
88 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/...
3
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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 ...
2
votes
0answers
40 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 ...
5
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0answers
121 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
56 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
votes
1answer
173 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 ...
1
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2answers
384 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
votes
1answer
186 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 ...
1
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1answer
96 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
votes
2answers
140 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
vote
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
votes
0answers
60 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 - $3000 K$ ...
2
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2answers
263 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
86 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 ...
4
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0answers
137 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
votes
1answer
484 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
votes
1answer
95 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?
3
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2answers
319 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
89 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
260 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
367 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 ...
6
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1answer
326 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
votes
1answer
366 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 ...
