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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32
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7answers
5k views

How do satellite motors keep themselves cool and lubricated?

I'm a high-schooler and today we were taught about the car engines and we were told that in order to maintain proper lubrication in order to reduce the heating effect of friction in the pistons using ...
6
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1answer
239 views

Can gas bubbles form in the fuel and oxidizer rocket engine pumps due to insufficient flow from the tanks?

In a staged combustion cycle rocket engine, the fuel and oxidizer are fed into turbo pumps which are in turn powered by a pre-burner. My question is how do they ensure that the fuel and oxidizer are ...
7
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2answers
678 views

Are In-Flight Electrically Heated Steam Rockets Possible?

I wonder if a rocket that uses electricity from internal batteries to heat water in its tanks to high pressure would be able to use that pressure to take off. Is it possible? I've researched here and ...
3
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1answer
178 views

Where do the numbers 101,972 and 3,600 come from in terms of Thrust-Specific Fuel Consumption (TSFC or SFC)?

Online, on sites such as Wikipedia's for Specific Impulse and Thrust-specific fuel consumption, there are these units: 101,972/x g/(kN·s) and 3,600/x lb/(lbf·hr) Perhaps 3600 comes from the number of ...
2
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2answers
217 views

Why aren’t vacuum engines turned on after Mach 1?

In rockets, smaller nozzles are used at lower altitudes because atmospheric pressure would cause problems by pushing air into nozzles with higher expansion ratios. However, it seems to me that once ...
0
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1answer
96 views

How do you calculate thrust produced by a rocket engine?

I was planning on building a water-powered rocket. I also wanted to know how high my rocket might go. Could someone help me figure out, how to calculate thrust produced by a rocket engine?
39
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6answers
7k views

How much has fuel efficiency increased in rockets since the Apollo missions?

I have been talking with a friend of mine and the subject turned to modern rockets versus Apollo era rockets and fuel efficiency. My friend stated that today’s rockets use half the fuel of the rockets ...
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0answers
58 views

Calculating thrust using only weight

How do you calculate minimum thrust for a rocket ship using just the weight of the rocket? How do you chose what engine you need to use for your rocket?
2
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1answer
71 views

Solid metal fuel for nano satellite thrusters

A South African company is developing a solid metal fuel thruster that was initially researched by NASA but was not further developed, an electric reaction could be used to vaporise solid metal fuel, ...
4
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2answers
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How to read this Cassini Main Engine Operating Box (oxidizer vs fuel tank pressures)?

The extremely cool NASA JPL video Triumph at Saturn (Part I) is really worth a watch and/or listen. At about 34:32 it covers the period just before SOI (Saturn ...
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1answer
460 views

How do you test-fire vacuum engines in a vacuum chamber? Why doesn't it fill up almost instantly from the exhaust and spray (deluge) water?

How are vacuum optimized engines tested without disintegrating them? is an excellent question as it's attracted quite a number of informative and diverse answers. @Uwe's answer informs us that there ...
2
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0answers
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How unusual is it to test vacuum engines at sea level?

How are vacuum optimized engines tested without disintegrating them? is an excellent question as it's attracted quite a number of informative and diverse answers. @Uwe's answer informs us that there ...
2
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1answer
39 views

Resources where one can find RD-171MV engine technical specifications? (e.g.TWR, Expansion Ratio, Isp, Thrust, Chamber pressure, O:F ratio)

I'm trying to get a hold of various technical specifications for the RD-171MV engine A modification of RD-171M being developed for the Irtysh rocket. Unlike RD-171M it's completely made from Russian ...
2
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1answer
177 views

Pressure inside Starship CH4 and LOX header tanks during entire Earth-Mars trip and landing on Mars?

What should be the pressure inside Starship CH4, LOx header tanks during the entire Earth-Mars trip and landing on Mars ? The main CH4, LOx tanks should be under 6 bar pressure, because that is the ...
4
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0answers
170 views

How many turbine blades, engine seals and bearings do reusable rocket engines have and how are they inspected?

From previous year statements of SpaceX representatives, the most difficult and longest part of used F9 booster refurbishment are inspections of the most volatile parts of the booster's nine Merlin ...
4
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0answers
73 views

A question about Nozzle/Extension/Skirt Size

In many rocket engines i see that the thrust chamber and a small part of the nozzle are one piece. Does anyone knows if there's a formula which determines what portion of the nozzle is A ? and how ...
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1answer
90 views

Difference between 2 pumps on same shaft run by a turbo pump and 2 pumps run on separate turbopumps

So i was trying to understand the working of the Full Flow Staged Combustion cycle(FFSC) and was comparing it to the Staged Combustion Cycle(SC) and Closed Combustion Cycle(CCC) a question came up in ...
7
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1answer
1k views

Using coolant as 3rd propellant

Rocket engines often have 2 propelants, one of which is used to cool the engine and after that the hot propellant is injected in the combustion chamber. Would make sense to have a third propellant ...
4
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2answers
517 views

What is the Isp of gunpowder likely to be? Could this table be right? Can it even be determined?

There are some unsourced refutations of the value for the Isp of gunpowder in the table shown below can be found under What kind of engine does this Isp = 1600 refer to? Is it cubesat-friendly? Alas ...
11
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1answer
243 views

Why is the flame color from the New Shepard engine orange?

New Shepard is described as using liquid oxygen and liquid hydrogen for its propellants. When hydrogen and oxygen burn, as in the Space Shuttle main engines, there is a short conical blue flame, ...
3
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1answer
162 views

Are the (relatively) new "all electric" satellite buses like the Boeing 702SP really all-electric? Are RCS and momentum unloading done with ions?

This answer to Can ion Thrusters be used for Reaction Control System? got me thinking about the new "all-electric" class of commercial satellite buses. Question: Are the (relatively) new &...
2
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1answer
222 views

Calculating total burn time for a rocket under constant acceleration with two propellant consumption rates

I tried posting this question on the Physics side of StackExchange but didn't get any response after a week, presumably because it was lost within the broadness of physics in general, so I'm hoping ...
4
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1answer
677 views

Rocket propulsion question help

I've attempted this question but once again got this wrong. Here is what I did I knew that the thrust equation was mass flow * (Vj - V0). I also knew that the mass ...
3
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1answer
183 views

What makes CAPSTONE-1's eight hydrazine thrusters so "super small, high-performance"? How do they work without any tank pressurization?

The NASA Ames Feature Innovative Propulsion System Gets Ready to Help Study Moon Orbit for Artemis says: CAPSTONE’s journey to the Moon will take about three months, starting with its launch to low-...
2
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1answer
142 views

Has Demonstrator-1 2021-006BX demonstrated a hydrogen-oxygen combustion engine fueled by electrolysis yet?

NASA's NASA CubeSat to Demonstrate Water-Fueled Moves in Space says: A NASA CubeSat will launch into low-Earth orbit to demonstrate a new type of propulsion system. Carrying a pint of liquid water as ...
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2answers
568 views

Technical feasibility of using Raptor engines for Vulcan rocket

According to a recent GAO report (p. 116), ULA's Vulcan rocket's BE-4 engines are "experiencing technical challenges" and there is some concern whether they will be ready / certified in time ...
1
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1answer
126 views

If building a liquid propellant rocket engine, with bi propellants, how does the dimensions of my Combustion chamber, affect the efficiency?

If building a liquid propellant rocket engine, with bi propellants, how does the dimensions of my Combustion chamber, affect the efficiency ? but also what is the best C* dimensions for an earth sea ...
19
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4answers
3k views

Can "engine" and "motor" be used interchangeably in spaceflight? Are there any cases where they can't be?

Typing "rocket motor" into google returns a page full of links mostly about rocket engines. It seems that The Google has AI-synonymized them. Question: Can "engine" and "motor&...
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0answers
177 views

What are the various ways that rockets measure the instantaneous thrust of each engine?

@DavidHammen's answer to Engine failure: how to detect? mentions thruster sensors. This intrigued me and so I thought I'd ask about how this is done. Thrust is a critical parameter to know in real ...
2
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1answer
145 views

What expansion ratio is the best for mars surface level engines?

What expansion ratio is the best for mars surface level engines? For launches from Earth, first stage nozzles are much shorter than second stage nozzles because of Earth's high sea-level pressure. For ...
2
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1answer
99 views

What was the volume of the Rocketdyne F-1 engine's main combustion chamber?

In the specifications of the F-1 available online, I can find its dimensions, weight, thrust, etc. but I couldn't find what was the volume of its main combustion chamber. Is this information available?...
3
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1answer
443 views

Conversion of heat into electricity in rocket nozzles

Can we use advanced thermoelectric materials to reduce the temperature of nozzles by converting heat energy to electric energy and reducing the strain on the nozzle material and the coolant while ...
0
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0answers
43 views

How could I find the pressure and/or the Isp at the exit of a rocket nozzle if I have data for the throat and comb. chamber?

I've been looking at this for some time and working with CEA which will only give me data points for the pressure, temperature, Isp, etc. for the Injection, Combustion Chamber End, and the Throat; but ...
3
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1answer
195 views

Are the engines present on the SpaceX Starship Sea level engines or Vacuum engines?

The SpaceX Starship will have engines that light up in space and propel the ship to Mars. Companies and organizations use vacuum engines in space. However, Starship has to land on Mars, travel back ...
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0answers
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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:
3
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1answer
64 views

Hypergolic Engine Diagram

Does anyone have any hypergolic rocket engine diagrams, preferably labeled but it's fine if they aren't? Thanks!
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1answer
88 views

Engine thrust gain with altitude [duplicate]

As you climb at launch, atmospheric pressure falls, causing thrust to rise. The thrust gain I'm talking about here is due to the increased ratio of nozzle pressure to atmospheric pressure. I'm going ...
3
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1answer
545 views

Open source liquid rocket engine

Is there an open source bi-propelant liquid rocket engine that would have all the documentation, computations, test results and 3D design files (CAD) freely accessible?
0
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1answer
167 views

Highest Isp achieved with nitrous oxide as oxidizer

What is the highest Isp achieved on orbital rocket for an engine that used nitrous oxide as oxidizer? Both hybrid and liquid engines can be considered. Not considering nitrous oxide monopropellant ...
5
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1answer
197 views

Is it possible to launch a rocket with steam by using a fission reactor?

The idea is to use a fission reactor to turn water into steam pumping it outside the reaction chamber through heat pipes.
2
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1answer
122 views

Potential Fusion Drive system calculation issue

I will start off by saying that this is an entirely hypothetical drive system with plenty of handwaving and optimistic physics. My question I think is fairly simple and may just be something that ...
1
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1answer
110 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 ...
3
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1answer
109 views

Cooling the nozzle extension of a nuclear salt water rocket (NSWR)

The nuclear salt water rocket(NSWR) uses a plutonium salt (at least to my understanding) dissolved in water as its fuel. The mixture is kept stable by filling the fuel tank with boron carbide, which ...
8
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2answers
410 views

Why are the rocket plumes on SN10 different colors?

At about 7:53 (T+2:30) in this official video of the SpaceX Starship SN10 test flight, the engines are shown in the lower right, with clearly different colors in the plumes. The one on the right is ...
4
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1answer
183 views

Why are Starship's tanks curved the way they are?

Since Starship has to feed its engines in two kind of situations : -during ascent, acceleration is colinear to Starship's longitudinal axis. -at the end of the belly dive, acceleration is normal to ...
3
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1answer
138 views

Can Falcon 9's engines be ignited more than 4 times if there is enough TEA-TEB?

SpaceX's Falcon 9 uses TEA-TEB as a ignitor for its Merlin engines. My question is if the rocket has more TEA-TEB, can the engine be shut down and restarted more than 4 times?
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2answers
3k views

Can nuclear thermal engine designs be shutdown in such a way as to be restartable, in space?

Nuclear thermal rocket designs have a working temperature of 2000k or greater. Shutting such a reactor down won't stop that heat production instantly - it'll take quite some time to cool. Do current ...
5
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1answer
708 views

Are nuclear thermal engine designs limited to about twice the Isp of existing chemical rocket engines? If so, why; what's the limiting factor?

Discussion below With Ultra Safe Nuclear engines and hydrogen propellant, how far to Mars could you get and still be able to return to Earth in an emergency? including a comment that suggests that the ...
7
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2answers
244 views

What happened to tripropellant rockets?

IIRC, tripropellant rockets can deliver superior performance compared to bipropellant rockets (at the cost of added complexity). Now, I know that there is the Li/H/F combo, but it isn't used because ...
6
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2answers
453 views

Solid state thrust vectoring

Usually thrust vectoring for the whole rocket is done by changing the orientation of individual engine(s) by hydraulic/electric actuators. So in this system the engine simply moves and with it the ...

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