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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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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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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60 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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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
672 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, ...
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1answer
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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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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
51 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 ...
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1answer
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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 ...
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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 ...
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335 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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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 ...
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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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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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3answers
69 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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476 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
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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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100 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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54 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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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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168 views

What are some of the important parameters to scaling a liquid rocket engine

Liquid Rocket Engines can be clustered together on a stage but their performance, weight and size largely decide and constrain the design of the launcher. Data on the newer smaller launcher engines ...
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1answer
68 views

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

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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103 views

Kerosene engine film cooling

So it is clear that kerosene fueled engines use two fluids for film cooling via injection in the combustion chamber, throat, or nozzle. (That is "true film cooling" and not just a fuel rich outer ring ...
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2answers
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Whats the difference between cryogenic and cryo storable rocket engines

I've read about cryogenic storable liquid rocket engine but since it doesn't refer to its fuel, I want to understand the difference between a cryogenic and a cryo-storable engine. The term cryo-...
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1answer
84 views

Where are the 6 22-N OSIRIS-REx engines?

Does anyone could link an image/3D model/photo that shows the 6 22-N engines? Related question: OSIRIS-REx engines location.
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OSIRIS-REx engines location

I'm trying to locate all the OSIRIS-REx engines. Here: http://spaceflight101.com/osiris-rex/osiris-rex-spacecraft-overview/ (Propulsion System) I read that there are: 4 x 275 N, 6 x 22 N, 16 x 4.5 N ...
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What is the status of the F-1B engine development?

In this article https://arstechnica.com/science/2013/04/new-f-1b-rocket-engine-upgrades-apollo-era-deisgn-with-1-8m-lbs-of-thrust/ and in several answers on this site a modernized F-1 engine is ...
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142 views

What factors determine the altitude at which rocket exhaust plumes start blooming hugely?

The images below are from a much larger set of photos in Spaceflight Now's August 8, 2019 article Photos: Atlas 5 paints the sky with spectacular sunrise launch. They show several effects related to ...
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118 views

How does a Hall effect ion thruster have a sea-level Isp of 800? Operates at 1 atmosphere?

Astronatix's SPT-100 lists the following: Stechkin electric rocket engine. Used on Meteor and Gals satellites. In Production. 1.35 kW Hall thruster. Thrust variable 2 to 20 kgf. ...
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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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How was sky crane (used on Mars Science Laboratory's Curiosity) tested?

This is sky crane: Mars has 1/3 of Earth's gravity, so how was sky crane tested on Earth? Did they even test it at all? Did they repeatedly do the math, and make sure everything works so that they ...
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189 views

Does central Merlin have a different specific impulse?

On a Falcon 9 booster, does the central engine experience unique variations of its ISP due to its plume bordering the eight other plumes? If there is any influence, how does the ambient relative ...
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555 views

Does static fire reduce reliability?

I do understand that static fire helps discovering malfunctions, as explained in this answer. A launch exerts an important stress on rockets' engines (high temperature and pressure, vibrations,...) ...
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502 views

What is the job of the acoustic cavities inside the main combustion chamber?

I am new to rocket engines. I was looking at an image of RS-25 engine's MCC and found these acoustic cavities, and I want to know how they work. Can somebody please explain their working principle? ...
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635 views

Compressed gas thruster for an orbital launch vehicle?

Is it possible for a compressed gas thruster to be used to launch a spacecraft into orbit? Let's say, it's already moving at 250MPH(111.7 meters/second) relative to the planets surface. Planets ...
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Would a nuclear turbojet with a chemical afterburner be a suitable intermediate between a pure nuclear turbojet and a nuclear thermal rocket?

NOTE: This is not the place to question the fundamental veracity of nuclear propulsion in aircraft and spacecraft. For context, in a spaceplane, the higher speeds you can attain under air-breathing ...
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183 views

Are there any rocket engines in current or former use that aren’t normally restarted in flight, but have the capability for an emergency restart?

(Inspired by my earlier question about restarting a flamed-out RS-25 SSME in flight.) Most rocket engines are not designed to be lit more than once.1 Most first-stage rocket engines, for that matter,...
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166 views

Are rocket engine feed pipes flexible?

Let's restrict this question to rockets whose first stage : run on liquid propellant use turbopump (this may be too restrictive for this question, but it still restrict to many rockets in use today -...
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101 views

Oxidizer Line Pressure of DIY Hybrid Rocket Engine Limits Thrust?

So I’ve seen engines like these which use gaseous oxygen as an oxidizer and then a solid tube as a fuel. But do these types of hybrid engines have any possibility of creating a useful amount of thrust?...
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Why did the manned Mercury-Redstone flights carry and use retrorockets?

The Mercury-Redstone programme, a subset of the Mercury human spaceflight programme, used a modified version of the Redstone missile for suborbital flights in space. It culminated in two manned ...
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Apollo CSM RCS maximum number of simultaneously active engines?

Reading the RCS subsystem manual, it seems like each RCS quad of the Apollo SM consisted of four hypergolic engines. Am I correct in saying that all four engines of each of the four quads could be ...
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Apollo CSM mass, inertia and RCS parameters?

Is there a document specifying the total mass, the 3-by-3 inertia tensor of the Apollo CSM assembly, as well as the geometry of the service module and command module RCS assemblies (in other words, ...
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Why could the Lunar Ascent Engine be used only once?

The Lunar Ascent Engine was used during the Apollo missions to ascent from the lunar surface back to the Command and Service Module. There was one risky aspect of that engine: it was not possible to ...
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139 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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Can the ISS boost maneuver engine be heard by the astronauts on board?

In the extremely cool demonstration video Demonstration of Acceleration Inside the International Space Station During a Reboost ISS Expedition 22 Commander Jeffry Williams says near the end at ...
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Why doesn't Rocket Lab use a solid stage?

I was just reading about the Scout, an all-solid rocket, and thought of Rocket Lab's Electron, which seems to have a similar mission of deploying small payloads to orbit. I understand the engines to ...
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What kind of methane-fueled rocket engines exist?

I have heard of methane being a strong contender for Mars and beyond. Methane is a cryogenic fuel and is said to have a high specific impulse, and work with closed- and open-expander cycles. I have ...
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343 views

Why don't all SSME turbopumps gimbal with the engine?

The SSME low-pressure pumps (both fuel and oxidizer) are mounted to the vehicle structure and don't gimbal. The high-pressure pumps are gimbaling with the engine, so the propellant lines between low-...
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Why does the Superdraco exhaust seem so under-expanded in this photo?

The Ars Technica articles From zero to 100mph in 1.2 seconds, the SuperDraco thruster delivers Dragon was destroyed just before the firing of its SuperDraco thrusters both include this "file photo" ...
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Why aren't air breathing engines used as small first stages?

I am wondering why we don't use jet engines as first stages. Most small rockets, like the Electron, can lift off with a small thrust. In the Electron's case, 192 kN. Why can't we replace the 9 ...