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Questions tagged [engine-design]

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

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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 ...
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0answers
54 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
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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 ...
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1answer
59 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 ...
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1answer
57 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
123 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
55 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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48 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
159 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
172 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
174 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
100 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
91 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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41 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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1answer
35 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
104 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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42 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
67 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
167 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 ...
6
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1answer
75 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
149 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 ...
10
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1answer
154 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
60 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 ...
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4answers
136 views

In the context of calculating mass flow rate from thrust and Isp, how would an additional efficiency be defined?

In this answer I show a quickie derivation for calculating a mass flow rate of a rocket from a known thrust and Isp. A comment there says: That assumes 100% efficiency and ignores the fuel ...
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0answers
50 views

Is it undesirable for LOx to splash on the walls of combustion chamber?

Typically, there are annular ports on the injector plate to introduce fuel to cool the combustion chamber. Why is LOx not used for cooling despite it being extremely cold? Given there will be a lot ...
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5answers
4k views

Have Air-breathing Engines ever been used on a reentry vehicle, could they be?

For the purpose of this question I would like to assume there is no risk of life for the astronauts, or that the design would only be used for delivery of a non-ethically-sensitive payload. Looking at ...
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2answers
2k views

What kind of antimatter engine is this?

I found this diagram while looking up diamagnetic machines. Could anyone explain what engine this is?
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0answers
83 views

Detaching parts of engine bell

I was looking at engine bells, and I was wondering: would it be possible or useful for a diamond shaped engine bell, that would stage sections off, creating a wider bell as the rocket leaves the ...
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2answers
74 views

How would the rocket differ in a higher atmospheric or ambient pressure?

I imagine the both rocket nozzles in either environment underwater or Jupiter or underground would have to be different than that of standard rocket nozzles because of the back pressure. In this ...
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3answers
187 views

At what size does a bigger solar sail stop increasing your acceleration?

Is there a point where the larger solar sail would not add more thrust? What is the most thrust a solar sail can produce? Can a solar sail be added to an ion engine and work better?
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1answer
85 views

How long does Augmented Spark Igniter fire?

The heroicrelics.org page J-2 Rocket Engine Augmented Spark Igniter mentions that The ASI operates continuously during entire engine firing Does this how all spark igniters function in rocket ...
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1answer
91 views

How is a spark plug igniter of rocket different from one used in IC engines?

US20120103302 shows a spark ignited prechamber combustion system typically used for IC engines. It basically consists of a chamber which has a input of premixed fuel-air mixture and a spark plug to ...
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1answer
142 views

Which of the orientation is preferred for static fire testing of a liquid rocket engine - vertical or horizontal?

Liquid rocket engine's hot fire testings are performed both vertically and horizontally. Vertical orientation - Falcon heavy, Falcon 9, Rutherford engine, UCSD Engine test from 2014 , Merlin 1D, ...
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2answers
2k views

Benefit of Raptor Engines

I know that the Raptor engines are significantly different from the Merlin 1-D's since they use liquid methane and are cryogenic. However, what exactly enables the Raptor engines to produce a lot more ...
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3answers
129 views

3D Printing Rocket Parts

The Rutherford Rocket engine is a 3D printed battery powered engine. While the engine is made for small rockets, is it possible to use elements of 3D printing and battery power for launches of bigger ...
5
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1answer
226 views

Which is the preferred mode of liquid rocket engine cutoff - fuel lean cutoff or fuel rich cutoff?

When a bi-propellant liquid rocket engine receives a command to shut down, will the fuel gets cut off first and then the oxidiser - a fuel lean cutoff? Will the oxidiser gets cut off first and then ...
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1answer
120 views

What is advantage of independent pumps vs common pump in clustered configuration?

The images of the engine clustering in the Rocket Labs's Electron rocket gives an indication that there are independent drive pumps for individual engines; I am not sure of it. I am not aware of the ...
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1answer
30 views

How to analytically estimate the pressure loss through an liquid injector?

A simple orifice and a pipe have well-documented pressure loss calculation. But when an injector has complicated flow patterns, is it possible to break it down into simpler sections by which the ...
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0answers
34 views

Which is preferred for liquid atomization - gas & liquid shear or liquid & liquid shear?

For generating a spray of droplets, liquid need to be disintegrated/atomized through shear forces. Typical injectors in IC engines and aircraft use shear between gas & liquid at the phase ...
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1answer
66 views

Materials used for turbopump construction for LOX

What are the materials used in the Rocketdyne F-1 engine's turbopump design and what was the pressure rise?
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4answers
251 views

Can a solar sail be added to an ion engine and work better?

Has there been a concept vehicle that uses both solar sails and ion engines? Does the added mass of each system increase or reduce the spacecrafts total detla V capabilities? Inspired by S.F. As S.F....
2
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1answer
98 views

How are the Titan Transtage's tanks protected from its engine?

As a follow up to this answer which identifies the two pointed objects flanking the Titan Transtage's engine in an unusual configuration as its propellant tanks: How are these protected from the heat ...
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2answers
213 views

What is the purpose of the “shaft” and “block” in these two different engine gimbal joints?

This question refers to the device which transfers the thrust force from the engine to the vehicle while allowing the engine to swivel - the "gimbal joint". Both the F-1 and SSME have a bolt- or ...
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1answer
122 views

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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0answers
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How do preburners work in gas generator cycle? [duplicate]

In gas generator cycle small portion of the fuel and oxidzier is burned in the preburner to drive centrifugal pumps feeding the main combustion chamber. But how is the fuel/oxidizer fed into the ...
5
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1answer
100 views

Rocket engine propellant/cycle combinations

I am trying to determine typical relationships between engine mass and performance for various types of engines, so I'm looking for a broad spectrum of examples to extrapolate from. I'm segregating ...
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1answer
69 views

Rocket engine power vs. Sound

Is there any relationship between the sound emitted from a rocket engine and the amount of thrust it gets at surface temperature and pressure?
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0answers
98 views

What is the droplet size that is desirable for pintle injectors?

The pintle injectors tend to generate droplets after impingement of the fuel and the oxidiser stream and I understand that the droplets will be premixed. In such a case, even a larger premixed ...
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1answer
198 views

How similar are nuclear ramjets to nuclear thermal rockets?

Russia is currently developing nuclear powered cruise missiles. These presumably use nuclear ramjet propulsion in the same way that the US's Project Pluto would have. Is there enough similarity ...