Questions tagged [engine-design]

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

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4
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2answers
176 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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2answers
125 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 says ...
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212 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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110 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
316 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
402 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 ...
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1answer
108 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
241 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 ...
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1answer
184 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 ...
2
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1answer
109 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
1k 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
71 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
5k 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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97 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
323 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
378 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
427 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
563 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
542 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, MASA ...
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2answers
3k 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
163 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 ...
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1answer
454 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
177 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
37 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
55 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
194 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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3answers
586 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 delta V capabilities? Inspired by S.F. As S.F....
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1answer
179 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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3answers
845 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
203 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
46 views

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 ...
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1answer
172 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
96 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
153 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
297 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 ...
5
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1answer
721 views

What would be the performance of a nuclear lightbulb engine with graphene instead of quartz?

The nuclear lightbulb is a closed-cycle gas-core nuclear propulsion system. It uses quartz to separate the nuclear fuel from the propellent, thus eliminating the radiation problems with open-core ...
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1answer
297 views

InSight Launch - Centaur Fuel Rich

During the launch of InSight today one thing sprung out to me: at T+408s the voiceover announces: Centaur slightly fuel rich. And again at ...
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1answer
484 views

How does the Space Shuttle's SSME engine's thrust vary after ignition?

After writing the question Do Blue Origin's BE-3 engines need to run for 7 seconds to “warm up”?, I took a look at the YouTube video SSME ignition sequence (found in What are the small gas jets at the ...
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2answers
623 views

Pro/cons of burning propellant in stochiometric ratio?

Several questions and answers here speak of stochiometric ratio. I do understand it is convinient for efficiency (greater ISP). I also read somewhere (I am unable ro find again the reference, it was ...
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1answer
118 views

If anything, what can cause a rocket engine to flame out prematurely?

I would assume that dropping flow rates or a drop in chamber pressure would cause the engine to stop thrusting, but I am unaware as to what specifically these conditions might be.
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1answer
270 views

Trade-offs in developing larger engines vs using more smaller engines

Looking to explore the inverse point of this question: What challenges are there for more, smaller liquid fuel engines instead of one large? As stated in the answer to the above question, fewer, ...
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1answer
1k views

Problems with the “How to Design, Build and Test Small Liquid-Fuel Rocket Engines” text

For those that have read or consulted the text: How to Design, Build and Test Small Liquid-Fuel Rocket Engines (Rocketlab/China Lake). Otherwise, see steps 10-13 here: https://risacher.org/rocket/...
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2answers
442 views

What are the choice of materials for LOx pumps casing and impellers?

Given the highly corrosive nature of LOx and the extremely low temperature, what materials are usually used for the LOx pumps? Steel, Copper, and many alloy tend to be flammable in liquid Oxygen ...
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0answers
174 views

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 ...
2
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1answer
820 views

Why spray LOx into combustion chamber, if GOx is more effective?

Are there any issues in transforming the liquid oxygen into gaseous oxygen before injecting into the combustion chamber? Gaseous Oxygen will be readily available for combustion and will mix well with ...
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1answer
2k views

What is the current status of EmDrive engine?

This engine was making news few years ago, but I have not heard much about it lately. Were there any updates regarding its tests, further development or anything?
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1answer
306 views

Don't Preburner exhaust fumes disturb the combustion in a Full-flow Staged Engine?

Since Full-Flow Staged Engine uses preburned fuel/OX-rich gases in combustion chamber, don't those exhaust fumes produced by the preburner somehow unbalance or 'pollute' the pure combustion of fuel ...
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1answer
180 views

Does regenerative cooling reduce specific impulse?

Specific impulse of exhaust velocity depends on the temperature in the combustion chamber. Won't regenerative cooling lower the chamber temperature, causing the exhaust velocity to decrease?
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1answer
661 views

How does turbine power output of a full-flow staged combustion engine compare to Oxygen-rich staged combustion?

One of the benefits of the SpaceX Raptor full-flow staged combustion engine is the extra power generated by having all of the fuel and all of the oxidizer flow through the turbines to produce power to ...