Questions tagged [engine-design]
Questions regarding the design or design process for a propulsion system.
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What makes CAPSTONE-1's eight hydrazine thrusters so "super small, high-performance"? How do they work without any tank pressurization?
The NASA Ames Feature Innovative Propulsion System Gets Ready to Help Study Moon Orbit for Artemis
says:
CAPSTONE’s journey to the Moon will take about three months, starting with its launch to low-...
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Why did the Soviet Union decide to use 30 small engines instead of a few large ones on the N1?
The N1 was a big disappointment after exploding on every single launch attempt. From what I have read, it seems like most of the attempts went wrong because one of the 30 engines exploded causing a ...
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Is the concept of the Epstein Drive based on actual theorized scientific research which is considered plausable?
I've always found it interesting when we see real life taking its cues from fictional arts, especially when it comes to Science Fiction technology. There are plenty of examples of classic books, TV ...
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What "unique control system" modulated GOCE's thrust to compensate for variable atmospheric drag? How did it know how to modulate it?
This answer to How much time did the longest maneuver last? says:
The GOCE satellite mission (Gravity Field and Steady-State Ocean Circulation Explorer) lasted 55 months (4.6 years) of largely ...
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Can coking be avoided by pumping fuel after shutdown?
As I understand it, coking in kerolox engines occurs when the engine shuts down and fuel flow stops, causing fuel still in the coolant channels to overheat and decompose.
Can this problem.be avoided ...
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Does an overexpanded nozzle behave like a suction cup?
It is generally said that, to obtain optimal specific impulse, a nozzle should be just the right size that the exhaust pressure is equal to the ambient pressure. Quoting this answer, a relevant ...
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What was the exhaust pressure of the Saturn V? [duplicate]
I am trying to write some code to simulate rocket launches, and I am doing a proof of concept using the Apollo 11 as a model, to fill my values. When calculating thrust I am using the equation:
F=m⋅Ve+...
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What are the major tradeoffs for a launch vehicle having either one 400 kN engine or eight 50 kN engines?
Given the problem of choosing to build and launch a small rocket to put a smallsat into orbit with either of these two configurations, what are the major tradeoffs between them?
For specific issues ...
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How to calculate the tank boost system for the displacement feed system?
There is a liquid rocket engine running on two components: highly concentrated hydrogen peroxide and kerosene, fuel vapor is ...
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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 ...
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What was the volume of the Rocketdyne F-1 engine's main combustion chamber?
In the specifications of the F-1 available online, I can find its dimensions, weight, thrust, etc. but I couldn't find what was the volume of its main combustion chamber. Is this information available?...
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Can a spinning water film cool an engine cheaper and better than ablative?
Ablative cooling us an incredibly simple way to cool a liquid rocket engine, when compared to regenerative cooling. But ablatively cooled engines are (presumably) hard to refurbish.
Why not inject a ...
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Combustion stability for the second stage of Sea Dragon
I was listening to a video about SHLV's (Super Heavy Launch Vehicles), and Sea Dragon's first stage engine was mentioned.
In terms of combustions stability, the suggested fix would be large combustion ...
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Rough values for the staytime or characteristic length of the combustion chamber of an oxygen/methanol rocket engine?
I'd like to have some idea of the staytime or characteristic length of the combustion chamber of an oxygen/methanol rocket engine.
Are there sources for this, or a way to estimate it?
I've tried, but ...
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Multiple engines vs one engine with multiple combustion chambers
What is the fundamental difference between a construction of n engines vs one engine with n combustion chambers?
For example, Energia rocket used four boosters, each with a 4-chamber RD-170 engine, ...
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Contraction Ratio Impact on Performance for Liquid Rocket Engine
How does one go about calculating the necessary contraction ratio (combustion chamber/nozzle throat cross sectional areas) of an engine with these parameters known...
thrust
nozzle throat area
mass ...
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Multi-stage combustion products?
Okay so I've never seen anything about this before, and that's probably for a very obvious, very simple reason I am far too dim to think of, but here goes:
Most combustion reactions in rocket chambers ...
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How do spacecraft protect their engines from micrometeroids?
A meteoroid impact on an engine bell can easily rupture a coolant pipe. Or it can create an imperfection in the backing plate from where cracks can form. Or it can destroy an injector. All of these ...
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How to find the correct size and angle for a conical nozzle on a rocket engine? [closed]
So I need to know the equations for finding the size and angle for a conical nozzle. I am making a rocket engine and I decided the conical nozzle would be the easiest to build. The rocket is going to ...
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Does methalox fuel have a coking problem at all?
Methane was chosen for SpaceX Raptor because it has less coking problem that kerosene. But does it completely eliminate it? If not, how much less severe is it?
I googled 'thermal decomposition of ...
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Why will the Raptor not face the same turnaround issues as Space Shuttle engines?
The RS-25's notoriously slow, expensive turnaround was blamed on its complexity. The Raptor appears about as complex.
Both use regenerative cooling.
Both use preburners to drive turbopumps.
While the ...
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SSME/RS-25:; Why arent high pressure and low pressure pumps coaxial?
The Space Shuttle Main Engine low pressure pumps to prevent cavitation at the main pumps. This pumps were driven by separate turbines fed by high pressure fluid from the main pumps. Why? It just adds ...
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SSME/RS-25: why seal between LOX pump and preburner?
Both the the fuel and oxidiser preburners ran fuel rich. In order to prevent the preburner gas from entering the LOX pump and blowing it up, they had this complex double seal with a gas purged void in ...
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How does SpaceX Raptor deliver a more benign turbine environment?
Raptor has been claimed to be able to deliver "long life ... and more benign turbine environments".
https://en.wikipedia.org/wiki/SpaceX_Raptor
The Raptor has hot oxygen flowing out of the ...
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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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Why was the NERVA program dropped?
At the very end, NERVA (Nuclear Engine for Rocket Vehicle Application) had developed nearly flight-ready engines able to:
operate for periods in excess of an hour while providing maximum thrust up to ...
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How "big" is a 2 megawatt preburner?
Reaction Engines recently announced a milestone completion in their SABRE development program:
we have tested the engine’s advanced hydrogen pre-burner at energy
delivery levels in excess of two ...
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Do smaller engines have a higher thrust to weight ratio?
For a given chamber pressure and shape,
thrust is proportional to nozzle area, which is proportional to the square of dimensions
mass is proportional to the volume, which is proportional to the cube ...
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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 ...
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Why do the Titan SRBs have an angled engine bell?
Looking at pictures of Titan rockets with solid rocket boosters, the bell is at an angle. Why would they do that?
https://historicspacecraft.com/Rockets_Titan.html
https://en.wikipedia.org/wiki/...
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attitude thrusters sharing a common combustion chamber
Most smaller satellites and other larger but simpler space craft with a less demanding mass fraction tend to use cold gas thruster, importantly with a common or as few as possible pressure vessels, ...
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Recent GPS III Launch Intended or Unplanned Venting?
Between 14:01 and 14:14 in the following video, there is a significant gas vent happening behind the engine bell:
Is this working as intended, or does that appear to ...
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What is a bimodal or multimodal space rocket engine? Especially a nuclear-powered one?
I can't seem to find a specific answer anywhere....
I wonder if it means using the radioactive fuel to power the electronic equipment, purely via natural decay, but also using the same fuel to power a ...
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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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Is there a way to make liquid fueled rockets not lose efficiency with decreasing throttle?
As far as I know liquid fueled rockets suffer from lowered efficiency when using less than full throttle since the pressure of combustion is lowered and so thermodynamic efficiency. Could a variable ...
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How to find the average ambient pressure during rocket ascent?
I am trying to find the average ambient pressure that my rocket will flight through during its ascent to then determine the most optimum conditions in my combustion chamber and nozzle.
I have ...
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Equations evaluating engine performance
What kind of equation would best evaluate a rocket engine's performance in foreign atmospheres such as Mars?
Does it matter that specific impulse does not consider air resistance? Should I focus on ...
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Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios?
Question: Why can solid rockets be both the skinniest and most spherical launch vehicles while liquid fuel rockets have a more limited range of aspect ratios? Are there fundamental engineering ...
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What engine cycle does the RS-88 and its hypergol derivative use?
A comment on this question Orange lines coming from rocket engine nozzle? stated in part
The RS-88 is not a full flow engine and there is not a visible bypass exhaust. ... Perhaps they eject the ...
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How does the open expander cycle separate the fuel for the pump and combustion chamber? [closed]
I'm designing a single open cycle expander rocket engine using propane. However, I've been unable to find out whether or not the fuel is split into the turbine and combustion chamber before or after ...
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Tory Bruno mentioned "unsolvable combustion instability" of "large methane engines". What, why, how?
Relevant tweet, an hour ago: https://twitter.com/torybruno/status/1405210138189864960?s=19
a Tweeted Question: Why wasn't methane used in the 2000s, when it was readily available unlike the time ...
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What are the negatives associated with Thrust-augmented Nozzles aka Afterburning Rocket Engines?
An interesting comment here introduced me to the concept of Thrust-augmented Nozzles aka Afterburning Rocket Engines. The pubs I've read on it so far introduce the concept as a way to provide good ...
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What are better ways to deliver heat directly to propellant in a Thermal Rocket design for use in launch than UV such as in the Nuclear Lightbulb?
Most advanced, high-power engine concepts that I came across aren’t suited for atmospheric launch, so I got curious about what kinds of engines could launch a very heavy craft from the surface of a ...
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What is the area of the SSME nozzle knowing only thrust at sea level and in vacuum?
Looking at the SSME Wikipedia RS-25 Space Shuttle Engines, the data shown that the thrust at sea level ($F_{sl}$) is 1.816*10$^6$ N, while the thrust in vacuum ($F_{vac}$) is 2.278*10$^6$ N. Knowing ...
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Discrepancies in thrust chamber dimensions for RL10
I've recently been developing some automated scripts in Python for the purpose of calculating engine parameters. I've been using the RocketCEA interface library, which links to NASA's Chemical ...
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How Spacex's Raptor Rocket Engine starts?
How does the Spacex Raptor rocket engine start? What are the different stages of startup?
Is the propellant pressure in the tanks sufficient to drive the turbopumps and ignite the preburners and then ...
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Paraffin wax in solid motors
Paraffin wax is often used in (at least hypothetical) hybrid motors, mostly with N2O or HTP. Could it not, however, be used in a conventional configuration? Running at O/F of 12.4, 60 bar chamber ...
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Question Deriving Mass Flow Rates for an Engine
I am trying to follow the calculations made in this blog post for a $50$ lbf. IPA/Nitrous Oxide engine, but cannot seem to get the values the author made for their propellant flow rates. Since the ...
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Does LOx stay as liquid when entering combustion chamber?
Given the heat from combustion and increased temperature, would the LOx still be in liquid form after emanating from the injector? Or will it instantly transform into gas?
Are injectors cooled using ...
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Estimations for Gas-Side Wall Temperature Within Rocket Engines
I'm in the process of reading Modern Engineering for Design of Liquid Propellant Rocket Engines and am stuck on this one example given in chapter 4 on the ...
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