Questions tagged [ssme]

SSME is the acronym for the Space Shuttle Main Engine. Sometimes called the RS-25, or RS-25D.

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Will the Artemis I SLS do a static fire on the pad following rollout?

Following the rollout for the Artemis I wet dress rehearsal, or the rollout for launch, will the core stage perform a static fire on the pad?
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Are there any plans on replacing the shuttle-era RS-25D's during the Artemis III/IV missions?

The last two Artemis missions which use the shuttle-era RS-25D engines will fly in 2025 and 2026. Is there ever a possibility that, in the case that Aerojet Rocketdyne delivers their RS-25Es (or at ...
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9 votes
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Two-Stage Fully-Reusable Shuttle

In chapter 6 of SP-4221 "The Space Shuttle Decision" they are talking about the fall of the "Two-Stage Fully Reusable Shuttle". In one paragraph they talk about how this Two-Stage ...
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Does anybody have a contact for the Docents for the Space Shuttles? [closed]

I would like to pass along the following information to the Docents for Enterprise (Intrepid Sea, Air & Space Museum in New York) and Endeavour (Los Angeles Science Center). Documents describing ...
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Why aren't ejectable engine blocks in use today?

Related to my previous question regarding expending the RS-25s. Why aren't engine blocks, especially those expensive RS-25s on the SLS, made ejectable from the fuel tank assembly and parachute to be ...
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Why isn't NASA planning on saving some of the RS-25Ds due to their historical significance?

A while ago, Scott Manley made a video about the Artemis program and how NASA will expend all its Block II RS-25D engines through the SLS's first four launches. Why isn't NASA planning on putting some ...
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3 votes
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From which NASA publication originates/where can I find the color version of this SSME flow diagram?

Sorry to ask such a similar question as the last one, but I already marked that one as answered. My friend who works at the Endeavour exhibit in LA found this diagram left on the ground after a ...
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From which NASA publication originates/where can I find a higher resolution version of this SSME flow diagram?

This came up when I was taking a look at Endeavour over in LA. Where can I find a readable version of this full flow diagram (valves, control systems, and everything)?
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RS-25E cost estimate but sentence confusing (approximately: help; maybe)?

So recently someone found out that the industry studies for SLS had been FOIAed by a site called government attic. While the other studies are interesting in their own right (check them out honestly), ...
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What specific device failed, causing engine #4 in the Core Stage Green Run to report a Failure Identification?

(See this Q&A for context if needed: What is a "Major Component Failure" referred to in news reports about the unsuccessful Space Launch System core stage test firing?) In the post-test ...
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What is a "Major Component Failure" referred to in news reports about the unsuccessful Space Launch System core stage test firing?

In reporting about the unsuccessful green run of the SLS core stage, Ars Technica mentions About 50 seconds into what was supposed to be an 8-minute test firing, the flight control center called out, ...
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Which RS-25s are on the Artemis 1 rocket?

The SLS core to be used for the Artemis 1 flight will use four RS-25 engines. These reusable engines were used on the Space Shuttle Orbiter previously. Is there a listing of which SSMEs are planned ...
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If rocket engines only need fuel and oxidizer, then why there are so many pipe lines on the engines?

If fuel and oxidizer are pumped by turbines to the combustion chamber, then why there are so many pipes around? It should only have a two-cylinder shaped turbine assembly. I doubt there are other ...
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7 votes
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Which are good resources to learn more about the components of a rocket engine?

A detailed and annotated image of a SpaceX raptor engine (found on a SpaceX website) illustrates that in addition to the major components (e.g. pumps, inlets, combustion chamber, nozzle), there are ...
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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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How long did it take to remove or install an SSME on the Space Shuttle?

Not knowing the steps involved, I am curious how long it took to remove or install an SSME (Space Shuttle Main Engine) in real life.
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Looking for a document that describes SSME test failures

At some point in the last 5 years I put together this matrix of Space Shuttle Main Engine test failures. The last 6 columns are documents which describe some of the incidents in more or less detail. ...
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Why did the SSMEs gimbal during ignition?

During Shuttle ignition sequence: the engines always slightly gimbal closer together as they reach full combustion (I'm guessing, from the plume appearance). Why?
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Why was the reusability of the SSMEs so poor, and why was this considered acceptable given their purpose to launch a reusable vehicle?

The Space Shuttle Main Engines operated for around 8.5 minutes in every Shuttle launch, yet were removed from the orbiter after each flight and went through an overhaul, parts often being traded from ...
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2 votes
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Shuttle main engines RS-25, material damage on parts that needed replacement/refurbishment

Since other members wrote, that my my original question here Shuttle main engines RS-25 refurbishment/material damage was too broad I modified it to asked just one thing, while the other questions I ...
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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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What (if anything) could have caused all three shuttle main engines to stop at the same time?

From my previous question, you'd have a bad time if it happened. What could cause it to happen, if anything? My parameters are: The engines must STOP, but not destroy the vehicle simply by having ...
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18 votes
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In a shuttle launch, what would have happened if all three SSMEs failed during flight?

I'm certain there are several flight regimes where this could happen, and that the procedures should be different for each one. For instance, this is a very different question before lift off than it ...
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3 votes
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What was the minimum throttle setting a SSME could be operated at while in Flight?

A very informative article on the RS-25 (SSME) indicates that it could be throttled from 67% to 109%. (http://en.wikipedia.org/wiki/Space_Shuttle_Main_Engine) I know on 51L the data indicates the ...
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8 votes
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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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3 votes
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How would the STS have differed if it used J-2's as the main engine?

In the spirit of counterfactual rocket design questions such as this one - how would the STS have differed from its actual design if it used J-2's as the main engine? What would be the loss in payload ...
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Why were the SSMEs so much more fragile than the J-2 engines?

This answer mentions that the J-2 engines used by the Saturn V's second and third stages were substantially more resilient than the "extremely complex and sensitive" Space Shuttle main engines. What ...
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What was the maximum thrust the RS-25 was capable of producing?

The Rocketdyne RS-25, a large hydrolox engine best-known in its role as the main engines (SSMEs) of the space shuttle orbiter, was originally certified to a thrust level of 1.67 meganewtons (mN) at ...
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Why is SpaceX's Raptor's design so simple in comparison to SSME?

What is especially striking to me is how simple Raptor is in configuration compared to SSME. The Raptor doesn't have an LP fuel or oxygen pump. What's even more surprising, if we are to compare the ...
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10 votes
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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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How much fuel/oxidizer was held in the piping of the Shuttle orbiter?

The space shuttle main engines were in the orbiter portion of the vehicle, but fed fuel (LH2) and oxidizer (LOX) from the external tank. Suppose the external tank is ejected before the LH2 and LOX ...
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Would the Space Shuttle External Tank have made orbit as a VT SSTO with 6 SSMEs?

Dropping the external boosters and also the entire 75-100 ton orbiter from the picture, would the tank all by itself have made orbit? This would require bolting at least 5, better 6, perhaps even 9 ...
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5 votes
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NASA's RS-25 Engines shut down time

As a follow up to my other question about RS-25's ramp-up time, I was wondering what would be the ramp-down times for the RS-25, i.e. what would be the time that takes to go from 100% thrust to 0% ...
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NASA's RS-25 Engines

I am developing a FSX-based space flight simulator FSX SpacePort. I've been trying to get the detailed specs on NASA's RS-25 engine, namely, what were the ramp-up times for this engine? As in, how ...
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Actuators for gimbaling of engine in rockets and launch vehicles

For controlling the rockets to stay on course, continuous engine control is require which is done by using gimbal actuators. What type of gimbal actuators have been used on SSME, Rocketlab's ...
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What is the geometric dimensions of turbo pumps present in SSME?

Here is a really well documented and detailed explanation of the SSME engine. Looking through this, one can notice that there are no details of the dimensions. I would like to know about the ...
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What is the purpose of the "shaft" and "block" in these two different engine gimbal joints?

This question refers to the device which transfers the thrust force from the engine to the vehicle while allowing the engine to swivel - the "gimbal joint". Both the F-1 and SSME have a bolt- or ...
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8 votes
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STS: How much thrust did the nominal post-MECO LOX dump produce?

Following up to some questions asked in comments to the answer to this question: With pressure-fed engines, is any measurable thrust generated by venting the pressurant out the engine bell after ...
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6 votes
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SSME propellant duct routing

The low pressure propellant ducts in SSME are routed around the engine in a somewhat complicated way. Both fuel and oxidizer lines leave the low-pressure turbopump, go around, down and then turn back ...
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How does the Space Shuttle's SSME engine's thrust vary after ignition?

After writing the question Do Blue Origin's BE-3 engines need to run for 7 seconds to “warm up”?, I took a look at the YouTube video SSME ignition sequence (found in What are the small gas jets at the ...
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Disposal pool during RS-25 engine test?

Nasa recently did a test firing of an RS-25 rocket, and released a video of it. Here's a frame grab: Note that pool of water at the bottom right, with a pipe leading to it, and clouds of steam coming ...
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7 votes
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RS-25 Hot Fire Test

Yesterday, NASA Stennis successfully completed a hot fire test of Aerojet Rocketdyne RS-25 a.k.a SSME. It was noted in the webcast before the test started that they were testing the 'engine controller'...
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6 votes
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Theoretical Max G forces on Shuttle Launch?

Reading this question Why are rocket engines operating above 100% often considered nominal? leads me to a question about throttling back the SSMEs in the later stages of a Shuttle Launch to limit G ...
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Why does the shock wave in this new 2017 RS-25 test also have a "bump" on one side? [duplicate]

In last year's question Why does the luminous blue shockwave from the RS-25 engine appear to be rectangular? I showed images of an RS-25 engine test from 2015, and what I believe to be a test of the ...
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Can SLS use subcooled LOX?

The SpaceX Falcon 9 FT is using subcooled liquid oxygen. I understand that LOX gets significantly denser at lower temperatures so more propellant can be filled in the rocket's tank. Can NASA SLS RS-...
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4 votes
1 answer
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Is it possible to estimate the nozzle characteristics of the Rocketdyne HG3 engine?

Boeing and the Marshall Space Flight Centre brought to pass many studies of improved Saturn V launch vehicles. The rockets proposed under the MLV and ELV projects would feature longer stages for more ...
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22 votes
3 answers
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How was fuel crossfeed achieved, between the main tank and the Shuttle?

Whenever a fan of Kerbal Space Program mentions the super-efficient 'asparagus staging' in any professional context, the automatic response is 'That won't work. KSP fuel pipes are pure magic.' The ...
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Which STS mission raised the normal engine throttle above 100%, and what change to the SSME made that possible?

As indirectly stated in an answer to How long does Max-Q last?, during later Space Shuttle launches the main engines were operating at above 100% of their nominal maximum thrust. Specifically from ...
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What does "in the bucket" mean?

I've heard this expression a couple of times before. It seems related to the engines, but I can't find any information on it, except in the context of testing them. Here's two videos where it occurs: ...
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What are the small gas jets at the rims of the Space Shuttle Main Engines?

As can be seen in close-up footage of SSME ignition, such as the video below, there are small jets of an unknown gas/vapor emanating from specific points around the ...
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