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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466 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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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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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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1answer
120 views

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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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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3answers
473 views

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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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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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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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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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?

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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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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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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Space Shuttle and SSME Servicing Procedures for Re-Launch

There's been a lot of discussion about SpaceX's ~30% price reduction from re-use of the first stage, which got me to wondering: why exactly was the Space Shuttle so expensive to service and prep for ...
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Was the third shuttle engine any different from the others?

The space shuttle used three SSME, organized in a triangle with two next to each other closest to the external tank, and one on top of those. I am pretty sure the first two engines were close to ...
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How do they simulate the SLS engine environment?

I was reading an Aviation Week article about the restart of SSME (RS-25E) production for SLS. There is a paragraph in it that is interesting to me. On the SLS, the engine inlets will receive ...
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How will the SLS first stage be supplied with engines? Copy manufacturing the RS-25 or replacing it?

The SLS is a very opinionated subject among bloggers. I'm looking for what substance there might be behind the following general claim (without specific source). Is it truthful and if so, what is the ...
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Was the notion of using an air-started SSME on Ares-1 a reasonable idea?

For whatever reasons, it seems like the standard upper stage engine in the U.S. inventory is the RL-10. A high performance engine with nice specific impulse (Isp = 450-465 s), but very low thrust (25 ...
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What are the costs of the various different engines in current use?

This may be impossible to answer, since the data is often not disclosed. But in an article, about ULA getting RD-180's from Russia it claims: Each engine reportedly costs between \$11 to \$15 ...
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Have SRBs or SSMEs ever launched without a space shuttle?

It seems to me that the April 12, 1981 launch of Columbia (STS-1) was the manned spaceflight with the most untested hardware of any manned space launch. Even the Vostok and Mercury launch systems had ...
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Can I drink the water from the plumes of SSME?

Shuttle's SSME uses cryogenic Hydrogen(LHX) and Oxygen(LOX) as their propellent to give hot water vapour. If I somehow manage to get the exhaust plume and condense it to liquid, Can I drink it ...
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Why not use Sparklers on Delta-4 Heavy launches to burn off the hydrogen?

With three CBC (Common Booster Core) modules firing their RS-68A engines simultaneously, a Delta 4 Heavy launch is an impressive sight. The RS-68 is a LOX/LH2 engine. As part of the launch sequence, ...
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In a cryogenic fuel rocket, at what pressure is the fuel injected into the engine?

The pressure in the Space Shuttle's main engines must be very high to get the vehicle off the ground (with the SRB assist, of course). With such high pressures inside the engine, how do you inject ...