Questions tagged [engines]

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

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14 views

What is the thrust of Momentus' thrusters?

I understand that they have an interesting method of using microwaves to produce plasma from water. They claim to have a "high" thrust and "high" specific impulse. Their Isp ...
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30 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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1answer
118 views

How do we maintain the RPM of turbo pumps in liquid rocket engine?

How do we maintain the RPM of turbo pumps in liquid rocket engine? And how do we control it? And in the case of electric pump fed engine (like Rocket Labs's Rutherford engine) is easy but how we do it ...
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1answer
111 views

What is a throat plug used for?

This cutaway drawing of the F-1 injector plate has a "throat plug insert" annotated. What is a throat plug? What is it used for?
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1answer
67 views

Combination of fuel cells and electric motors - whether it has been used as part of an electric pump-fed engines?

In electric-pump-fed engines fuel pumps are electrically powered and batteries are used as source of electricity. Yet there is another source of electrical energy which could be used in theory - fuel ...
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56 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

Which engine has the highest nozzle wall temperature? [closed]

From all the rocket engines that were used in flight, which one has the highest nozzle wall temperature? The nozzle wall is not heated uniformly. But there are regions where they reach max temperature....
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3answers
2k views

What is the lowest first stage thrust for a launch reaching orbit?

What is the lowest thrust for a first stage rocket for a rocket that reached Earth orbit?
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52 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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1answer
65 views

Outsourced rocket engines for medium and small launchers

Is there any company selling rocket engines that work for small and medium orbital launchers other than Ursa Major Technologies? Looks like a good model: the company developing a rocket can save a lot ...
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1answer
66 views

Why maintain nominal engine inlet mixture ratio for a gas generator engine?

I was reading up on gas generator cycles and came across the following paragraph talking about fuel or oxidizer rich gas generators and the different mixture ratios for the main combustion chamber ...
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121 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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1answer
65 views

How throttle changes affect calculations of thrust?

So, for constant throttle setting equation to calculate thrust looks like $ \ F = \dot{m}_\mathrm e V_\mathrm e + (p_\mathrm e - p_0) A_\mathrm e$ But if we are looking at flightclub.io simulation, ...
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1answer
90 views

Concerns/challenges with LOX as a regenerative coolant

What are the fundamental issues that make LOX as a regenerative coolant difficult to work with or less ideal than using fuels as a coolant instead in small scale engines (<7000lbs of thrust/ ...
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61 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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1answer
314 views

Contracting rocket engine nozzles

The efficiency of rocket engine nozzles depends greatly on their expansion ratio an how well the ambient pressure matches the rocket nozzles exit pressure. An optimal expansion ratio means that there ...
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80 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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132 views

Trying to make a program to calculate (liquid) engine size. Can you please help me check for any problems?

So as the title says I am trying to write code to calculate engine size and some other parameters. For the equations, I used mostly : Sutton's Rocket Propulsion Elements 8th Edition, and for the ...
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1answer
1k 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 ...
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1answer
272 views

Why do RS-68s suffer ignition failures?

NROL-44 failed to be in space for yet one more night last night, this time because of an automated hotfire abort triggered when one of the outboard (iirc) engines on the Delta IV Heavy failed to ...
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76 views

Need help finding a clean expression for exit velocity [duplicate]

I'm trying to calculate a engine burning LOX and ethanol (96%) and for that I am using both CEAgui, a GUI for NASA's CEA (Chemical Equilibrium with Applications) code Sutton's Rocket Propulsion ...
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75 views

Would rotating detonation rocket engines always require high pressure fuel pumps? [duplicate]

The question Performance of a pumpless liquid rocket engine is thoughtful and provocative and pretty much all answers include a mention of the extremely high pressure necessary to push propellants ...
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57 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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Why there are small holes just at the ending of RS-25 rocket engine? [duplicate]

I have seen these holes in many pictures and I can't understand what are these and why are they used?
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96 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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38 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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3answers
208 views

What (if anything) limits the efficiency of a rocket engine?

Humans have developed lots of rockets. I observe that in most cases to increase the payload capacity we just increase the amount of fuel. Is it not possible to exponentially increase the efficiency ...
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Full Flow Staged Combustion Benefits vs Closed Staged Combustion [duplicate]

I am aware that the RS-25 space shuttle engine was a closed staged combustion engine, and used two preburners (both fuel rich) to drive the turbines and pumps to pump the LOX and fuel into the ...
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1answer
196 views

From what material and how are the Merlin engines and nozzles of it (sea level) manufactured?

I am specifically interested in the alloy used to build the engine, also about the nozzle: Is it just in one piece or welded using different sections. If they are welded then which welding techniques ...
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1answer
254 views

Purpose of foil on Merlin Vacuum Engines of SpaceX

I want to know what is the purpose of this silvery foil situated above the bell in Merlin Vacuum Engines, and what purpose does it fulfill exactly?
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2answers
189 views

Why is rocket engine flame usually clear/transparent at the nozzle?

This is a followup to a question about why the Falcon 9 second stage flame was invisible when out of the atmosphere. See: Why is the flame of the Falcon 9's 2nd stage invisible?. That was well ...
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1answer
64 views

How much time did the longest maneuver last?

For this question, "maneuver" will designate any maneuver involving a change in $\Delta V$ (either direction, intensity, or both). The maneuver implying rotation only (such as the one the Hubble space ...
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55 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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1answer
91 views

Are Zvezda's engines replaceable in orbit?

This answer mentions that Zvezda has S5.79 engines for reboosting the ISS. Wikipedia mentions that this engine has a burn time (ie. lifetime) of 2700 s. Dividing that lifetime by Zvezda's age (20 ...
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1answer
110 views

Does injection provide any significant thrust?

In all liquid rockets, you've got to inject the fuel into the combustion chamber at a higher pressure than the combustion chamber itself. This is why turbopumps may be used--to raise the pressure ...
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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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1answer
67 views

Pressure withstanding capability

As you can see in this pic, F-1 rocket engine consists of 15 main components. Now, how is it possible to keep all the components together intact in high pressure situations like when the rocket is in ...
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1answer
310 views

Why do larger and newer rockets not use electric pumps?

Rocketlab's Electron uses an electric pump combustion cycle with no preburner so all fuel is fed into the combustion chamber rather than wasted in a preburner/staged combustion-powered turbopump that ...
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1answer
704 views

Why does the core stage of the Ariane 5 produce more thrust in vacuum?

In listening to a youtube video that was discussing the Ariane 5, the narrator noted briefly in passing that the Vulcain 2 engine produced more power thrust in a vacuum than it did at sea level. Not ...
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73 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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53 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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69 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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1answer
2k views

What actually is RP-1, and how is it different from any other hydrocarbon liquid fuel?

Related: Russian "kerosene" versus American "RP-1", however that's more about the details of specific rocket kerosene specs than rocket kerosene in the context of hydrocarbon and ...
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1answer
294 views

How many Lunar Module Ascent Engines were produced? How many still exist?

I know of two LM Ascent Engines still in existence. I believe Grumman built 13 Lunar modules. I also think at least 5 engines were tested at White Sands. So that is 18 that were built at a minimum. ...
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1answer
3k views

How do engineers know new engines will work nominally once they reach space?

Obviously you test fire a new engines as many times as you see fit on earth, but how do you know the effect the vacuum of space (or really the lack of gravity/air) will have on a new engine? Is it ...
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2answers
8k views

What is a thrust puck on Starship?

Elon Musk recently mentioned a Thrust Puck on Twitter, "We’re stripping SN2 to bare minimum to test the thrust puck to dome weld under pressure, first with water, then at cryo." He also mentioned ...
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1answer
40 views

What was the mass of the Viking sounding rocket engine (XLR-10-RM-2)?

I can find information about the XLR-10 for its sea level & vacuum thrust and specific impulse but not about its mass. What did this thing mass? Was it gimballed?
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64 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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101 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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1answer
103 views

How is pressure distributed in the combustion chamber of a rocket engine?

How, if at all, does the pressure of the combusting fluid change within a combustion chamber from the injector to the choke? Is it monotonically decreasing in pressure as you go from the injector to ...

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