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Questions tagged [engine-design]

Questions regarding the design or design process for a propulsion system.

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6 votes
2 answers
596 views

Rocket engine with lowest Isp to reach orbit

Which engine with the lowest possible specific impulse has reached orbit propelling a given rocket? There is a page at Wikipedia that compares orbital engines but some engines are missing Isp value ...
1 vote
1 answer
162 views

Why should nozzles be perfectly expanded?

If I understand it correctly, the only problem with an overexpanded nozzle is (aside from technical difficulties) that the surrounding atmosphere puts pressure on the exhaust gases and reduces engine ...
1 vote
0 answers
234 views

Really weird engine nozzle design

This Martin design for an Single Stage To Orbit orbital satellite Launch Vehicle was part of the High Altitude Test Vehicle (HATV) program. Credit: © Mark Wade http://www.astronautix.com/m/martinhatv....
2 votes
1 answer
121 views

Choice of Ammonia and oxygen as liquid rocket propellants in vortex combustion

I have been thinking lately about the benefits of using liquid ammonia and oxygen as rocket propellants, where ammonia is difficult to burn, what if in a fuel rich closed cycle, ammonia is used to ...
2 votes
0 answers
85 views

Would (Dual Concentric inline Powerhead) FFSC Cycle engine be possible to engineer

I,ve been wondering if it was possible engineer and how we would we work it out DUAL preburner inline FFSCC ENGINE with concentric core and individual concentric turbine inside one another and maybe ...
2 votes
0 answers
139 views

Atlas V RD-180 Analysis

I was tasked with researching certain properties of the RD-180 engine. I am finding contradictory information, or I am unable to find it at all. I am looking for the following information Mixture ...
7 votes
5 answers
1k views

Would reusability affect the performance of a rocket engine compared to a single launch version of that rocket engine

Reusability of the rocket engines, which are the most expensive part of the rocket, is very important to keep low cost of the space rockets and in this way making reality the space programs considered ...
4 votes
1 answer
120 views

Solar Reflective Plasma Drive

I understand that solar sails have just recently been progressing to be of use. Could the solar sails be positioned to create a hyperbolic mirror to super heat a substance to produce propulsion along ...
2 votes
0 answers
41 views

How to calculate the cooling jacket of a liquid propellant engine with an external component? [closed]

When designing a small rocket engine with a thrust of 100 N, questions arose about the cooling of the combustion chamber and the nozzle apparatus. It was decided to ...
13 votes
2 answers
23k views

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 ...
13 votes
3 answers
12k views

How is chamber pressure determined for rocket engines?

I've been looking for this for quite some time now, and I can't find anything other than calculations where they already assume a chamber pressure. So my questions are two: What are the equations for ...
1 vote
0 answers
51 views

Combustion chamber pressure calculation [duplicate]

A liquid propellent rocket engine: how is combustion chamber pressure calculated? Is it the different between turbopump outlet pressure and the drop in the injectors (losses aside)? Thanks!
1 vote
1 answer
138 views

Question on improved SSME thrust chamber construction

How do you get the closed out copper liner of the thrust chamber, which is hour glass shaped, into a jacket that is also the exact same shape like shown? I'm gonna guess it was done by diffusion ...
3 votes
1 answer
206 views

RS-25 Component weight

I need to determine the weight for specific components of the RS-25 Rocket engine. Namely the combustion chamber and nozzle separate from all other engine components? I must have found hundreds of ...
3 votes
2 answers
635 views

Fueling the RS-25 Turbo pumps?

Is there any way to know the weight of Fuel / Oxidizer consumed by just the turbo pumps of the RS-25 rocket engine?
5 votes
1 answer
382 views

Does electric fuel pumping scale well for rockets?

The Electron launch vehicle first stage has nine Rutherford engines In addition to adapting the single-engine-out-friendly nine engine configuration from the Falcon-9, the rocket carries a significant ...
15 votes
2 answers
2k views

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 ...
11 votes
1 answer
3k views

Have there been rocket engines designed for diesel? What ISP theoretically possible?

Have there been rocket engines or even test engines that have used diesel as a fuel? If so, what oxidizer had they used and what ISP did they achieve? If not, is it possible to say what ISP is at ...
3 votes
1 answer
558 views

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-...
37 votes
4 answers
9k views

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 ...
5 votes
1 answer
142 views

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 ...
0 votes
0 answers
97 views

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 ...
1 vote
0 answers
119 views

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 ...
2 votes
0 answers
143 views

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+...
3 votes
0 answers
147 views

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 ...
0 votes
0 answers
45 views

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 ...
17 votes
1 answer
8k views

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 ...
2 votes
2 answers
540 views

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?...
1 vote
1 answer
237 views

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 ...
2 votes
1 answer
101 views

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 ...
1 vote
0 answers
53 views

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 ...
10 votes
1 answer
2k views

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, ...
2 votes
0 answers
138 views

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 ...
1 vote
1 answer
101 views

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 ...
6 votes
0 answers
236 views

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 ...
1 vote
0 answers
177 views

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 ...
7 votes
2 answers
704 views

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 ...
3 votes
1 answer
339 views

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 ...
0 votes
0 answers
110 views

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 ...
4 votes
1 answer
779 views

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 ...
0 votes
1 answer
117 views

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 ...
5 votes
1 answer
635 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 votes
3 answers
2k views

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 ...
2 votes
0 answers
106 views

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 ...
7 votes
3 answers
5k 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
1 answer
1k views

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/...
5 votes
3 answers
128 views

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, ...
3 votes
0 answers
66 views

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 ...
0 votes
0 answers
57 views

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 ...
3 votes
2 answers
2k 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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