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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2
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1answer
72 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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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
57 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
40 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 ...
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1answer
97 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?
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1answer
46 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 ...
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1answer
149 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.
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1answer
67 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 ...
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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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1answer
65 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 ...
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2answers
231 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 ...
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1answer
156 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 ...
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1answer
104 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
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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 ...
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1answer
589 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 ...
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2answers
201 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 ...
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2answers
404 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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1answer
75 views

How do I calculate thermochemical properties of mixed gases?

I'm working on a rocket project, and my design of engines is stalled. I need to be able to calculate the Cp, Cv, and R for mixtures of O2/CH4 (stoichiometric or fuel-rich mix) and CO2/H2O (result of ...
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1answer
144 views

How much power do radiation-based engines produce

I heard that the Voyager satellites used a radioactive source to power the computer and sensor systems. How much power can this technique produce nowadays? Could it power, say, a fighting robot? ...
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59 views

Why are rocket engines shaped like a bell rather than a gun barrel? [duplicate]

When blasting matter out of a spacecraft engine for thrust, it seems like you'd want as much velocity in one direction as possible. Why do spacecraft engines (e.g., Apollo CSM) have big bell-shaped ...
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0answers
50 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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177 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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1answer
118 views

Could New Horizons' thrusters' ISP be as low as 157 sec?

A discussion below How much of a deep space spacecraft's structural mass is useless dead weight after launch? Any plans to shed it in the future? has lead to https://nssdc.gsfc.nasa.gov/nmc/...
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1answer
3k views

How many ion thrusters would be needed to accelerate a 1000 tonne craft at 9.8m/s²?

If we assembled an array of today's best ion thrusters in orbit, (the x3?) how many would be needed to accelerate a 1000 tonne spacecraft at 1g? I'm thinking Space Tug, for repeated Mars missions. ...
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1answer
71 views

Rocket engine with lowest Isp to reach orbit

Which engine with the lowest possible specific impulse has reached orbit propelling a given rocket? There is a page at Wikipedia that compares orbital engines but some engines are missing Isp value ...
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378 views

How can firing a Space Shuttle OMS engine below 21 km cause its nozzle to “collapse”?

This answer to Can the space shuttle use OMS engines during landing? says: No and quotes Section 3.7 of the Orbital Maneuvering System Workbook; OMS 21002 October 10, 2006, Final version, USA006500 ...
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4answers
133 views

How do pressure-fed engines stay cool?

Does anyone know how pressure-fed/hypergolic rocket engines cool themselves down? Do they regenerativly cool themselves? Thanks!
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7answers
3k views

Are there any hand-sized rocket engines?

Are there any rocket engines that are small and light enough to be held in one or both hands? Gas, liquid and hybrid designs are fine but solid motors are excluded (with the exception of solids that ...
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0answers
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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2answers
209 views

Longest static fire?

What is the longest duration for a static fire of a complete rocket stage? Initially I wanted to ask this for Falcon 9 and Falcon Heavy I found a 10 second static fire for Falcon Heavy - https://...
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1answer
128 views

How powerful do cold gas thrusters normally get?

Modern rockets like the Falcon 9 use cold gas thrusters for steering on landing approach when the engines are dead. Cold gas thrusters are common in smaller satellites and spacecraft, which way a ...
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1answer
101 views

How can you calculate a course based on constant acceleration burn and deceleration burn?

In the TV series The Expanse, a sci-fi space-engine called the "Epstein Fusion Drive" is a thruster capable of performing constant acceleration (up to and beyond "20g" (about $200 ...
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1answer
445 views

Is there an acronym for secondary engine startup? SESU?

We have acronyms for main engine cutoff (MECO) and secondary engine cutoff (SECO). Do we have an acronym for secondary engine startup---SESU maybe?
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3answers
193 views

Can liquid rocket engines have the same thrust as solid rocket engines?

Take the Vega rocket launcher for example. Its first three stages are solid rocket engines and burn at a relatively short time. If I were to change its first stage into a liquid rocket engine, can ...
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1answer
78 views

Why isn't the engine's Case-Throat-Nozzle reusable in Virgin Galactic's SpaceShipTwo?

I raed on https://www.smithsonianmag.com/smithsonian-institution/engine-powering-future-civilian-spaceflight-enters-collections-180971493/ (mirror): RocketMotorTwo is a hybrid rocket motor that ...
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2answers
3k views

Was there an anomaly during SN8's ascent which later led to the crash?

In SpaceX'S video, there is a conflagration inside the engine enclosure which seems irregular at around 1:49:49. The engine far left of the engine camera stops working and a few seconds later some ...
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1answer
66 views

What happened to continuously-applied heat barrier coatings in engines?

In Ignition, Clark describes an interesting approach to thermal control in rocket engines using oxygen as an oxidizer and hydrocarbon fuel: A small amount (few percent) of silicone oil or another ...
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1answer
54 views

Small liquid rockets are hard/expensive to build, but what about to use them?

It's become a sad and oft-demoralizing truism that it's quite difficult and expensive to design or build even low-performance liquid-fueled rocket engines, and that amateurs -- even those with skills ...
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2answers
168 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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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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1answer
157 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
121 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
72 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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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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0answers
87 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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0answers
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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2answers
117 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
77 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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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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