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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19
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1answer
1k views

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

It's well known that RP-1 is a particular specification for refined kerosene, but what actually is it and how is it distinguished from any other liquid hydrocarbon fuel?
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1answer
281 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
4k 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
36 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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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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0answers
93 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 ...
5
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1answer
89 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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115 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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2answers
100 views

What is the theoretical max specific impulse of rotating detonation engines in space flight?

I am curious if a rotating detonation engine were made stable, how much more efficient it would be than a standard rocket engine. With a methane or hydrogen and LOX mixture, what is the theoretical ...
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1answer
151 views

Why were later Russian engines inferior to the NK-33?

In terms of thrust-to-weight ratio the NK-33 engine developed for the Soviet N-1 rocket was by far the best in the world at the time, with a thrust-to-weight ratio of 137. But subsequent Russian ...
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113 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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1answer
148 views

What is the efficiency of liquid-liquid vs liquid-gas vs gas-gas engines?

I've read somewhere that gas-gas engines (engines where both the fuel and the oxidizer enter the combustion chamber as gases) have greater efficiency of combustion as compared to liquid-liquid or gas-...
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2answers
132 views

Does chamber pressure have the same impact on ISP for different types of engines?

From this answer I understand that higher chamber pressure means higher ISP - but is this always the case for similar engines? For example: I noticed that a lot of upper-stage engines have pretty low ...
42
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2answers
6k views

Why were the Space Shuttle's main engines placed on the orbiter?

Since the main engines can't be used after external tank separation, what's the reason for having the engines on the orbiter rather than just building a third rocket on the stack instead of the ...
8
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1answer
630 views

was Saturn V engine J-2 throttleable?

Were the J-2 engines of the third stage of Saturn V throttable? I know that the F-1 for first was not, but what about J-2? I could not find any information about it. Any reference or info for this? ...
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0answers
107 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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0answers
85 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 ...
5
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1answer
3k views

Could Stirling Engines work on sunlight alone?

With the heated side facing the sun and the rest in its own shade, could two contra-rotating Vacuum Stirling Engines and flywheels, in tandem, accumulate torque, to power a reaction wheel? Can the ...
4
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1answer
218 views

Is there anything fundamentally wrong with 'autogenous expander cycle`?

This question is a spinoff from here. To set the context, here is my understanding of the expander cycle: Closed expander cycle is very efficient, perhaps more efficient than staged combustion cycle....
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1answer
574 views

Why aren't expander cycle engines used on lower stages?

Looking at the simplicity of BE-7, I was wondering why dual closed expander cycle engines are not used more commonly and, as far as I know, are not used as lower stage engines at all. A commonly ...
8
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0answers
165 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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2answers
93 views

How were the LR-105, -79, and -89 ignited?

These engines were derived from the Navaho program and were used on the Thor/Delta, Jupiter/Juno II, and Atlas I families of launch vehicles. All were ground-lit only, but by what mechanism were they ...
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545 views

As of January 2020, what is the single longest duration firing executed with a Raptor engine?

Can someone cut through the woo for me? As of January 2020, what is the single longest duration firing executed with a Raptor engine? Have any successfully run for full mission duration? Sourced ...
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1answer
183 views

Is the Helical Engine EM-Drive a real aproach to spacecraft propulsion?

I read that the first test was a failure but another theory says that could be done but it may violate the laws of physics. Is this engine a near future possible propulsion system or is just theory ...
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1answer
176 views

Where are the lost RS-25D Block 2 engines?

There were 21 RS-25D Block 2 engines made. Two of them never flew. Three of them were lost with the Columbia disaster. 16 of them are tagged for SLS's use, including 14 previously flown, and the two ...
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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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1answer
172 views

What was the first rocket with de Laval (convergent-divergent) nozzle to fly?

Rocket engine Wikipedia article states that Goddard was the first to use a De Laval nozzle on a solid-propellant (gunpowder) rocket engine, doubling the thrust and increasing the efficiency by a ...
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1answer
179 views

Confusion about reactive force of a rocket

I am confused about the equation describing the reactive force of a rocket. I read from this source this equation: where M is mass of the rocket, u is the velocity of exhaust gas in an inertial frame ...
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1answer
144 views

In a rocket engine, do the propellants come out as liquid or gas if they’re cryogenic?

My cousin and I were talking about this and we could not come to a conclusion. Obviously it is very hard to keep cryogenic propellants at a liquid with the temperatures involved, but if they ...
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67 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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1answer
112 views

Why do many ablative nozzles use phenolic resin and not some other resin?

I am currently looking into ablatively cooled nozzles. Most of the nozzles made out of composite material that I have found use phenol as resin (Space Shuttle Solid Rocket Booster, ARCA Excecutor). ...
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1answer
90 views

What is a typical sea-level engine nozzle/expansion ratio? What about vacuum engines?

On a sea-Level engine, what is the average nozzle ratio? What about an upper-stage vacuum engine?
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3answers
233 views

Ion Drives specific impulse somewhat of a false economy?

I've been working through a thought experiment with a friend of mine, with some of my previous questions already being (very helpfully) answered on here :) Here's the current issue I have though - ...
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1answer
708 views

VASIMR - Propellant usage data?

So I am using the VASIMR data of approximately 5N of force per 250kw of power draw. As far as I can see, this scales fairly linearly, so 500kw would result in 10N of force. (Might require two engines, ...
2
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1answer
105 views

How do Expander Cycle Engines Inject Liquid Fuel During Startup?

My understanding is that the H2 in an expander-cycle engine is vaporized by the heat from the combustion chamber and nozzle wall. This is used to power a turbine and then get injected, in gas phase, ...
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0answers
50 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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1answer
57 views

Why would the ideal mass flow rate be less than that of real life?

Comparing the mass flow rate at the throat using the below theory, I find that the mass flow rate isn't accurate but isn't always larger than that of the engine specs (ideal assumptions ). What ...
2
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1answer
92 views

What materials can withstand corrosive oxygen-rich hot-gas environments inside rocket engines?

Russians figured out the metallurgy behind those super alloys since the N1 moon rocket era. Blue Origin is running its BE-4 engines on oxidizer-rich preburners and SpaceX’s full-flow Raptor engines ...
5
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2answers
256 views

Why was Apollo 11 launched in summer?

The question could seems stupid, but I think that best moment to launch a rocket is when temperature is lowest in order to achieve the best performance in a reaction engine. I do not know if there is ...
2
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2answers
388 views

How will SpaceX's Starship's future pressure-fed thrusters work at “any gee’s, any attitude”?

In the SpaceX video Starship Update at about 57 minutes Tim Dodd the Everyday Astronaut asks about how the Starship rotates from reentry orientation to landing (vertical) and Musk explains that in the ...
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2answers
103 views

Is the RD0146 an open or closed cycle engine?

RD0146 has been in the latest family of engines being developed from both Russia and US(Pratt and whitney). However, there is a lack of clarity in estabishing whether the expander cycle engine is open ...
4
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1answer
53 views

How many hydrolox engines had a methane variant?

Russia, has developed many rocket engine concepts over the years and its noticeable that they already tried liquid methane as a propellant back in the 90s. How many of their cryogenic engines had a ...
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0answers
47 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. ...
2
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3answers
78 views

What is the exit diameter of the LE-5B liquid hydrogen Engine used in H-II

I've found many documents that leave out the exit diameter of the LE-5B hydrolox engine. If anyone has found the detail in any public doxuments, I would appreciate it. If you can still provide the ...
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2answers
509 views

What is the difference between an engine skirt and an engine nozzle?

I have seen "engine skirt" and "engine nozzle" both used for the bell-shaped end of a rocket engine. Is there a difference?
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1answer
241 views

What is the plume effect?

I got introduced to the term "plume effect" in an answer I got here. A simple google search did not explain it, but from the link provided in the answer -- Space Shuttle Technical Conference Volume 1 ...
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1answer
109 views

Is it possible for one to adapt engine data for different fuels wrt liquid rocket engines

Liquid Rocket engine design is quite complicated and idealised and assumed theories rarely get sufficient validation. In an effort to verify/validate newer/untested fuels to be used in engine designs, ...
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1answer
61 views

What impacts do the rocket engine cycles have on the sizing of the components and effectively the engine?

For a given performance requirement, combustion pressure, propellant mixture, etc. How can one vary between the various engine power cycles such as gas generator, staged combustion, expander, and how ...
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1answer
108 views

What parameters drive the development effort and cost of a liquid rocket engine for orbital launchers(LEO - GEO)?

The development cost for a rocket engine drives the cost for a launcher and can be attributed to some basic parameters Apart from the few below, what others may be critical to developing and designing ...

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