Questions tagged [engine-design]
Questions regarding the design or design process for a propulsion system.
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How do toroidal and linear aerospike nozzles compare?
What are the pro's and con's of toroidal and linear aerospike engines with respect to each other? When does one choose one design over the other?
A linear aerospike is characterized by multiple ...
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1answer
196 views
Why did the Agena-D leak oxidiser when starting its engine?
The Agena-D upper stage, although extremely reliable, had a tendency to leak some of its RFNA oxidiser when starting its Bell 8096 engine; although not a problem for a stock Agena-D, it did cause ...
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2answers
172 views
Why was the reusability of the SSMEs so poor, and why was this considered acceptable given their purpose to launch a reusable vehicle?
The Space Shuttle Main Engines operated for around 8.5 minutes in every Shuttle launch, yet were removed from the orbiter after each flight and went through an overhaul, parts often being traded from ...
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1answer
70 views
What is a typical sea-level engine nozzle/expansion ratio? What about vacuum engines?
On a sea-Level engine, what is the average nozzle ratio? What about an upper-stage vacuum engine?
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41 views
Deep throttling in sea level engines
In this excellent answer, asked for merlin engines deep throttling in first stage and produced here.
To help you understand where the cross over point is, here is some math for understanding the ...
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1answer
56 views
Why would the ideal mass flow rate be less than that of real life?
Comparing the mass flow rate at the throat using the below theory, I find that the mass flow rate isn't accurate but isn't always larger than that of the engine specs (ideal assumptions ).
What ...
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1answer
116 views
Why did Virgin Galactic decide to use a hybrid engine vs liquid on their space ship?
To me, it seems like their business case is very dependent on rapid reuse. With this in mind, using a hybrid engine that would need to be replaced every flight seems very counter intuitive vs a liquid ...
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1answer
116 views
Why does the RL10 engine have a pipe sticking out of the side on the Centaur rocket?
The RL10 is a expander cycle engine so the pipe can’t be for a gas generator.
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2answers
98 views
Is the RD0146 an open or closed cycle engine?
RD0146 has been in the latest family of engines being developed from both Russia and US(Pratt and whitney). However, there is a lack of clarity in estabishing whether the expander cycle engine is open ...
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Are there any staged combustion cycle rocket engines under 1000 kN? Is it easier to produce larger engines with this type of engine cycle?
I found that most engines developed with staged combustion cycles are inherently quite powerful. Are there any engines which was developed with the staged combustion cycle with a thrust under 1 MN. ...
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62 views
Maximum speed of rocket propellant flow?
In reading this question (Limiting factors of liquid rocket engine thrust), it prompts me to ask if there is an upper limit in how fast the propellant/oxidizer can be pumped into a combustion chamber ...
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1answer
103 views
Is it possible for one to adapt engine data for different fuels wrt liquid rocket engines
Liquid Rocket engine design is quite complicated and idealised and assumed theories rarely get sufficient validation. In an effort to verify/validate newer/untested fuels to be used in engine designs, ...
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55 views
What impacts do the rocket engine cycles have on the sizing of the components and effectively the engine?
For a given performance requirement, combustion pressure, propellant mixture, etc.
How can one vary between the various engine power cycles such as gas generator, staged combustion, expander, and how ...
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1answer
108 views
What parameters drive the development effort and cost of a liquid rocket engine for orbital launchers(LEO - GEO)?
The development cost for a rocket engine drives the cost for a launcher and can be attributed to some basic parameters
Apart from the few below, what others may be critical to developing and designing ...
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2answers
210 views
Do any rocket engines besides the F1 need/require baffles?
The F1 engine required baffles on the injector plate to control combustion instabilities so that it wouldn't blow itself up. Was that unique? Or do other engines also have baffles for the same reason? ...
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1answer
173 views
What are some of the important parameters to scaling a liquid rocket engine
Liquid Rocket Engines can be clustered together on a stage but their performance, weight and size largely decide and constrain the design of the launcher. Data on the newer smaller launcher engines ...
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1answer
168 views
Magnetic force-driven propulsion system for an interplanetary/interstellar spacecraft
I have come up with a conceptual idea of a magnetic force-driven space propulsion system. What I believe is very unique about this propulsion system concept is that its working principle should not ...
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1answer
109 views
Kerosene engine film cooling
So it is clear that kerosene fueled engines use two fluids for film cooling via injection in the combustion chamber, throat, or nozzle. (That is "true film cooling" and not just a fuel rich outer ring ...
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2answers
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Saturn I's four outer engines' gas generator exhaust, why not vent to the side like the four inner engines?
At about 04:58 in Scott Manley's new video NASA Might Be Giving Away A Saturn I Rocket - Here's Why I Love This Vintage Booster he says:
So the four engines in ...
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2answers
119 views
Whats the difference between cryogenic and cryo storable rocket engines
I've read about cryogenic storable liquid rocket engine but since it doesn't refer to its fuel, I want to understand the difference between a cryogenic and a cryo-storable engine. The term cryo-...
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2answers
125 views
Is it possible to use hybrid propulsion to drive the turbopump?
Turbopump are driven either by a preburner or by an electrical engine (OK this technology is quite new and currently in 2019 only used on the Rutherford engine).
If I understand correctly, using ...
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1answer
303 views
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-...
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66 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 ...
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1answer
510 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? ...
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1answer
226 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 ...
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2answers
155 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 viability 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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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 ...
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2answers
114 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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47 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
80 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 ...
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1answer
187 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 ...
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1answer
265 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
93 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 ...
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1answer
181 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 ...
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2answers
654 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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103 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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1answer
146 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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3answers
970 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 ...
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1answer
370 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
65 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 ...
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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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198 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 ...
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1answer
86 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 ...
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1answer
353 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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455 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
127 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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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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43 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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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 ...
