Questions tagged [engines]

Questions regarding equipment used to propel a spacecraft or a rocket. Questions about attitude control jets should be tagged "attitude".

48 questions with no upvoted or accepted answers
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266 views

What is the heaviest part of a rocket engine?

I'm trying to understand how much different parts of a rocket engine weigh. For example, according to Wikipedia, Merlin engine weighs 470 kg, of which 70 kg is the turbopump. How is the remaining 400 ...
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96 views

Is thermal soakback from the engine a problem for rocket stages? Especially ones that complete several burns over several hours (e.g. S-IVB, Centaur)?

Thermal soakback is a phenomenon whereby a hot, operating engine transfers heat into the spacecraft, usually conduction through the engine mounts. I've only ever seen this problem discussed with RCS ...
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148 views

What performance can be expected from chemical rockets under Venusian atmospheric conditions?

Is it feasible to use either solid or bipropellant liquid rocket engines to lift off from the surface of Venus? "Reference datum" air pressure on Venus is around 9.3 MPa; even on the top of, say, ...
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92 views

How much cheaper are pressure fed engines compared to other cycles (e.g. staged combustion, gas generator, electric pump-fed)?

It's well known that pressure fed engines are mechanically simpler, and therefore cheaper than pump-fed cycles (although pressure fed has worse performance). However, I haven't found any sources that ...
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178 views

What is this ring-shaped part falling from Starship SN9 after launch?

The picture shown is a screenshot during the recent launch of SpaceX's SN9 from a live stream, and I noticed that a black ring fell off the exhaust/engine. It only shows up for around a frame or two ...
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80 views

Low-pressure pump-fed rocket engine?

I saw the above suggested in LEO on the Cheap. In P.130 it says: A compromise between high-performance/lightweight pump-fed vehicle designs and cost-optimized pressure-fed vehicles with heavier ...
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104 views

Why does kerosene need inducer?

We see inducers before the main kerosene turbopump in engines such as F1 and RD180. Given the property of kerosene having extremely low vapor pressure (~0.007 bar around room temperature), is this ...
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152 views

Why does Orion's Jettison Motor, have four nozzles but eight Attitude Control Motors arranged in an octagon?

Spaceflight 101's Orion Spacecraft Overview shows the following tests for the escape system. Why are there eight ACS thrusters arranged octagonally? Is it just to reduce cosine losses or does this ...
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182 views

Purging process of a rocket engine

Does spacex purge Falcon 9 engines after landing ? If so, which gas is used for purging?
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67 views

What do the RD numbers of Russian rocket engines mean?

Most Russian rocket engines have a name on the form of for example RD-107 (РД-107). But apart from different engines having different numbers, how is the number chosen? All RD-2xx engines appears to ...
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79 views

Cooling an aerospike spike via “fuel diversion”?

My question is, could an aerospike be cooled via diverting a very small quantity of your fuel (fuel used since it has a higher heat capacity than oxidizer and won't, you know, turn your engine into an ...
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55 views

Atmospheric retro-propulsion performance of aerospike nozzles?

I’m thinking about the use of single toroidal aerospike engine for a reusable upper stage with propulsive landing capability and this question came to mind. Do aerospike nozzles even capable of retro ...
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660 views

If the J-2X is too powerful for SLS, why was it appropriate for Saturn V?

Reading an article about new engines for the SLS (Summary: There is no plan what to do once the current SSME's are expended), they mention that the J-2X is too powerful for the upper stage of SLS. ...
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56 views

What is the mass of the Electron rocket's battery pack?

I am trying to estimate battery weights for electric pump fed rockets of various sizes and wanted to use the electron rocket as data to validate my calculations. However I was unable to find the mass ...
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128 views

What are these white garbage-like things on Falcon 9 vacuum engine?

On recent launch I noticed, that some white things jumping on vacuum engine in space. Something like garbage or condensate. See video at right at times when Earth is at left: ...
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74 views

(Possibly fictional) Can you locate this mysterious Project Orion design with NERVA engines as RCS?

Some years ago, I happened to see a drawing of a hypothetical Project Orion (the Nuclear Pulse Propulsion one) type spaceship, that had the notable (and highly questionable, IMO) feature of having a ...
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117 views

Why are hydrogen pumps much more powerful than oxygen pumps in rocket engines?

In many rocket engines I've seen, hydrogen pumps seem to be 3 - 4 times more powerful than oxygen pumps while pumping about 5 times less mass. Why is that? Part of this is probably driven by relative ...
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173 views

Can expander cycle engines fueled by methane or propane be practical?

It seems like all expander cycle engines currently in operation or in development use liquid hydrogen as fuel. The answer to this question indicates that RP1 won't work for EC engines because of its ...
3
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1answer
306 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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63 views

What main engine used in a series of environmental satellites has failed more than once (according to the GAO)?

A GAO report on NASA's ongoing projects can be found here. On page 70 while discussing the Lucy mission, it says the ... main engine was the same model used on a series of environmental ...
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207 views

Problems with shutting off “torch igniter” during the operation of combustion chamber

With reference to the presentation pp 76, where SSME's Augmented Spark Igniter is said to have their flame "On" even after the main combustion chamber ignition, is to prevent the blowback from the ...
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211 views

Why would “Breakthrough Starshot” need photon thrusters?

Found here (italics added, bold in source): Nanocrafts are gram-scale robotic spacecrafts comprising two main parts: StarChip: Moore’s law has allowed a dramatic decrease in the size of ...
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50 views

What happens to ablative nozzles after a test fire?

For example RS-68 engine If you make a test fire of an ablative nozzle engine then the fire will consume the coating of that nozzle. That means you have to replace the coating or the entire nozzle. ...
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56 views

What are the nuclear energy challenges specific to the moon?

What are moon specific hurdles to a fission reactor? low gravity no atmosphere Apparently it's more difficult to shed heat in a vacuum. Are some coolants more advantageous on the moon than others? ...
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40 views

Anyone know of a “N71” Hall Effect Thruster currently in production or development?

In a NASA Goddard Q&A transcript for an upcoming proposal, the NASA representative mentioned that the mission designers were considering the "N71" Hall Effect Thruster as an option for an upcoming ...
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56 views

Real-Time Launch Statistics for the Demo-2 Mission

Is it possible to view the statistics such as pounds thrust and pressure of the Dragon Spacecraft's engines in real time. I'm not sure if Space-X or NASA has a part of their website dedicated to this, ...
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189 views

Would this 'hybrid expander cycle' engine be practical?

This is another attempt at making closed expander cycle a bit more efficient (the first attempt was here). The design combines some elements of both the open and the closed expander cycles (hence the "...
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81 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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50 views

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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136 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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176 views

What are the maintenance benefits of SABRE engine technology for SSTO launchers?

What are the maintenance benefits of the SABRE engine over all the other engines being considered for the propulsion concepts for SSTO Reusable launchers?
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1answer
264 views

What is the O/F mixture ratio and the ISP for the SuperDraco Engine by SpaceX?

Is it safe to assume a mixture ratio of 2.16 with an ISP of 313 s for the NTO/MMH, SuperDraco Engine manufactured by SpaceX? I am referencing the 2.16 propellant mixture ratio, and estimating or ...
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51 views

Sources for values for realistic thrust calculation exercise?

I want to use this simplified equation to calculate the thrust of multiple different real engines: $$F = \dot{m} V_e + (p_e - p_0) A_e$$ Source: https://www.grc.nasa.gov/www/k-12/airplane/rockth....
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60 views

Freezing problem of hydrocarbon fuels in a LOX cooled engine

I assume that in a LOX/RP-1 engine where RP-1 is used as a coolant, we need not consider the freezing issues. The reason for my assumption is that we need not bring the chamber and injectors to the ...
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109 views

How do single-nozzle staged combustion rockets control roll?

Related: How do single engine rockets control roll? While many single-nozzle motors are gas generators & can deflect the pump exhaust asymmetrically to produce a torque, staged combustion motors ...
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68 views

OSIRIS-REx engines used during micro-maneuvers

During the Orbital-R phase, the ORX performs 12 micro-maneuvers (values obtained from NAIF's data file and SPICE library): ...
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161 views

Shuttle main engines RS-25 refurbishment/material damage

There was some thread here on Space Stack-Exchange about RS-25 refurbishment, but I am interested now, how this refurbishment look from the point of material damage of SSME hardware. In the early ...
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107 views

Are there any other examples of right-angle exhaust diverters in spacecraft?

The Scott Manley video The Only Pilot to Shoot Down A Spacecraft - A Space Ace talks about the ASM-135 ASAT and its successful test launched from an F-15. He shows images from the page The F-15 ASAT ...
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64 views

How does a “hybrid orbital raising system” based on R-4D (N2O4/MMH) + SPT-100 (Hall effect) work exactly? (Intelsat 38 & 39)

Astronatix's Intelsat 39 lists the two engines SPT-100 Stechkin 1.35 kW Hall thruster. R-4D Marquardt N2O4/MMH rocket engine. 490 N. Question: Why is this combination on Intelsat 39 called "hybrid" ...
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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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268 views

How do you calculate total Thrust and Specific Impulse for a rocket stage?

Given the stage has the following configuration: Thrust 741.4 kN (Main) 47.1 kN (Vernier) Specific impulse 297.999 s (Main) 288.999 s (Vernier) How ...
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55 views

Generating an electric field for a colloid thruster

I was wondering how the electric field in an electrospray thruster works to ionize particles and propel a micro spacecraft. I was thinking of possible circuits but I wasn't sure what it could look ...
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286 views

Pintle injector in a Vortex Cooled Chamber Wall (VCCW) Engine

All the articles I have found show the VCCW engines using flat plate injectors. With the inherent combustion stability of a Pintle injector system, it would seem to be a better choice, yet I find no ...
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33 views

Why does the RD-0110 Injector have a larger cone spray angle in the outer element rather than the inner element?

Wouldn't a large cone spray angle in the inner element (oxidizer) impinge with the outer element spray cone (fuel) and facilitate better atomization and mixing? Here are the RD-0110 Injector specs:
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1answer
41 views

Attitude control with cold gas thrusters

Consider the cold gas thrusters on a Falcon 9. There are two thruster pods on stage 1 and two on stage 2. Each pod has four orifices to fire along the x, y, and z axes of the scacecraft. By varying ...
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65 views

VASIMR thruster at scale

I am working on making one, the truth is that the principles are not so difficult, but does anyone have any plans? or reference "with numbers"? because the truth is that it is quite difficult to scale ...
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177 views

How are Voyager's 16 thrusters oriented?

@RussellBorogove's excellent answer to the question How do Voyager 1's Trajectory Control Thrusters differ from its Attitude Control Thrusters? describes the locations and usage patterns of the 16 ...
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103 views

What is this yellow light on the side of the 2nd stage nozzle - Shenzhou-11 launch

According to Wikipedia the single engine on the 2nd stage is a YF-20 series engine. What is causing the faint yellow light on the side of the nozzle where there is a tube wrapped around it? above: ...