User avatar
Tugger
Topic Author
Posts: 7518
Joined: Tue Apr 18, 2006 8:38 am

RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Mon Feb 26, 2018 4:19 pm

I have been in love with the SSME for a looong time. They work, and work. and have kept working through all the other problems the shuttle had. Now they have tweaked them and improved the power by 9% (constant). They just tested them at 114% for 4 minutes.

https://www.youtube.com/watch?v=hFEJuC_4IVY
Image

Here's an older picture but shows some more of her beauty:
Image

And here is the RS25 doing what it was designed to do:
Image

These engines are right up there with the Saturn F1 in my mind for being incredible engines that worked as designed and performed fantastically in their job.

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 
TheSonntag
Posts: 4414
Joined: Wed Jun 15, 2005 7:23 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Mon Feb 26, 2018 4:38 pm

Fantastic machines. It feels a bit sad to fly them up as loss-articles. SpaceX is showing the way, but that would be a bit Overkill for SLS possibly.

Those engines just h a d to work. A loss during most times of the ascent would have lead to loss of Crew and vehicle during STS times...
 
User avatar
Dutchy
Posts: 5216
Joined: Sat Nov 03, 2007 1:25 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Mon Feb 26, 2018 4:52 pm

On what program are they going to be used?
Many happy landings, greetings from The Netherlands!
 
User avatar
Tugger
Topic Author
Posts: 7518
Joined: Tue Apr 18, 2006 8:38 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Mon Feb 26, 2018 5:22 pm

This is for NASA's Space Launch System:
Image


And I must admit, what disgusts me about this program and its plan for the RS-25 is that they will become single use.... That is a travesty.

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 
parapente
Posts: 2426
Joined: Tue Mar 28, 2006 10:42 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Mon Feb 26, 2018 9:53 pm

I wonder how much water gets evaporated during such a long duration test such as that.

Making them disposable-soooo 1970's.Shame
 
ZaphodHarkonnen
Posts: 535
Joined: Sun Jan 04, 2015 10:20 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Tue Feb 27, 2018 10:30 am

Let's be honest. The chance of them having more than one SLS test launch is pretty slim. The thing costs half a billion per launch and NASA funding is a disgusting mess of pork barrelling.

And on top of that the launch tower is already leaning and may only be used for that one test flight.

If Blue Origin and SpaceX get their big rockets working then the SLS will be out of a job. New Glenn and BFR respectively.
 
estorilm
Posts: 226
Joined: Fri Jan 16, 2009 3:07 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Tue Feb 27, 2018 5:12 pm

Considering the complexity and performance of that engine, it has proven to be essentially bullet-proof to the very end (maybe not the end after all?) I'm definitely a huge fan of it, but as a human-rated design from the ground up, it's always been incredibly expensive (combined with US/NASA standards.)

As far as the advanced booster design is concerned, I REALLY REALLY hope Pratt & Whitney Rocketdyne can win a contract for an Apollo-era F-1B booster, though dramatically simpler, cheaper, and rated at 1.8M lb-thrust.

I really hate that I missed seeing the most powerful single-chamber rocket ever before my lifetime - seeing something like take flight could capture the imaginations of millions again.
 
DfwRevolution
Posts: 9116
Joined: Sat Jan 09, 2010 7:31 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Tue Feb 27, 2018 9:48 pm

Tugger wrote:
I have been in love with the SSME for a looong time. They work, and work. and have kept working through all the other problems the shuttle had. Now they have tweaked them and improved the power by 9% (constant). They just tested them at 114% for 4 minutes.


estorilm wrote:
Considering the complexity and performance of that engine, it has proven to be essentially bullet-proof to the very end (maybe not the end after all?) I'm definitely a huge fan of it, but as a human-rated design from the ground up, it's always been incredibly expensive (combined with US/NASA standards.)


That's overlooking some extremely close-calls suffered by the SSME during the Shuttle program. STS-51F and STS-93 could have easily resulted in loss of crew with a different roll of the dice. NASA was still troubleshooting issues with the SSME tank pressurization valves into the early 90s, which were critical safety items.

Just because the SSMEs never caused an Orbiter loss does not make them "bulletproof."
I have a three post per topic limit. You're welcome to have the last word.
 
estorilm
Posts: 226
Joined: Fri Jan 16, 2009 3:07 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 2:16 pm

DfwRevolution wrote:
Tugger wrote:
I have been in love with the SSME for a looong time. They work, and work. and have kept working through all the other problems the shuttle had. Now they have tweaked them and improved the power by 9% (constant). They just tested them at 114% for 4 minutes.


estorilm wrote:
Considering the complexity and performance of that engine, it has proven to be essentially bullet-proof to the very end (maybe not the end after all?) I'm definitely a huge fan of it, but as a human-rated design from the ground up, it's always been incredibly expensive (combined with US/NASA standards.)


That's overlooking some extremely close-calls suffered by the SSME during the Shuttle program. STS-51F and STS-93 could have easily resulted in loss of crew with a different roll of the dice. NASA was still troubleshooting issues with the SSME tank pressurization valves into the early 90s, which were critical safety items.

Just because the SSMEs never caused an Orbiter loss does not make them "bulletproof."

You're not speaking relatively here - those engines were applied to a REUSABLE space program the likes of which has never been seen before (or since). Space-X is doing amazing things, but the thrust and efficiency levels, combined with a non-human-rated design makes it completely unrelated - even then we're talking about 60's-70's tech.

I'm well aware of STS-51 and the well-known "limits to inhibit" radio call. There's a million parts in that engine, and I have no clue how you're questioning the success of the design based on a bad batch of sensors from a random contractor. This is precisely why the engine is "human-rated" and has redundant backups, internal health monitoring, etc including the ability of the flight controller to inhibit automatic shut-downs of the remaining engines. Obviously it's a lot easier today with high-bandwidth data links and more elaborate plausibility protocols and engine management software, etc.

400+ "engine-missions" and a single in-flight failure on one of the most complex liquid-fueled rocket engines (and first reusable) ever made? A design out of the 70s? It's a spectacular piece of engineering, and your "with a different roll of the dice" comment is ridiculous. You're flying 1/4 million-pound aircraft into space - everything is a "calculated" roll of the dice.
To say that engine achieved a 99.7% reliability rating and a 100% mission-success rating (ie. most abort protocols require multiple engine failures anyways) speaks for itself.

I mean if you had to be strapped to an engine (even near that thrust class) and sent into space, name ONE other design you'd feel safer on?
 
WIederling
Posts: 5904
Joined: Sun Sep 13, 2015 2:15 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 3:15 pm

estorilm wrote:
I mean if you had to be strapped to an engine (even near that thrust class) and sent into space, name ONE other design you'd feel safer on?


RD-107 family? :-)
Murphy is an optimist
 
ZaphodHarkonnen
Posts: 535
Joined: Sun Jan 04, 2015 10:20 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 3:34 pm

From memory didn't the SSME's need what was essentially a full teardown and rebuild after every flight? It isn't like they got to the point where SpaceX appear to be with a minor check on the engines and only some parts replaced between flights.

Amazing engine, but still essentially single use between flights.
 
LightningZ71
Posts: 392
Joined: Sat Aug 27, 2016 10:59 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 3:39 pm

A LOT of the reason for the full tear-down was the Human Space Flight Rating requirements. While, yes, they did need servicing between flights, the level of service applied to them was beyond what was required for normal operation and went into a level of detail that was likely "extreme". NASA had the time and budget to give them that sort of attention. While I will concede that they were certainly not to the level of re-usability of the modern Merlin's on the F9, given the era that they were developed in, they were arguably extremely re-usable comparatively. As a modern engine, yes, they do have some issues. The updates going into this revision should be addressing many of those. And, no, I don't remember those issues individually and don't have the time to site sources. There is a wealth of information out there on them online.
 
WIederling
Posts: 5904
Joined: Sun Sep 13, 2015 2:15 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 3:48 pm

ZaphodHarkonnen wrote:
It isn't like they got to the point where SpaceX appear to be with a minor check on the engines and only some parts replaced between flights.


That is on the horizon. But SpaceX definitely is not there yet.
Murphy is an optimist
 
parapente
Posts: 2426
Joined: Tue Mar 28, 2006 10:42 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 4:19 pm

Well I guess this 'new'idea of a moon orbiting space station will give it something to do.But they ought to get on and build whatever it is they want to put out there.The present lack of commitment other than pictures is somewhat strange-is there any real commitment?
Clearly Spacex are saying they will just land their BFR second stage directly on the moon (cargo/people).
So no need for either a cisluna space station or lander for them.
Also (as I understand it) their BFR refuling (for Mars missions) is going to take place in LEO so again no need for a space station.

2 very different routes it seems.
 
User avatar
Tugger
Topic Author
Posts: 7518
Joined: Tue Apr 18, 2006 8:38 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Wed Feb 28, 2018 8:27 pm

WIederling wrote:
estorilm wrote:
I mean if you had to be strapped to an engine (even near that thrust class) and sent into space, name ONE other design you'd feel safer on?


RD-107 family? :-)

Another great engine and design. :yes: But they are only half the rated trust of the RS-25 and are single use (which is also arguably a huge accomplishment it that alone, being able to be as reliable for as long as they have been. Modern single use engines certainly do meet that but still for the time the RD-107 has been active it is still impressive).

Tugg
I don’t know that I am unafraid to be myself, but it is hard to be somebody else. -W. Shatner
 
DfwRevolution
Posts: 9116
Joined: Sat Jan 09, 2010 7:31 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Thu Mar 01, 2018 3:39 am

estorilm wrote:
I'm well aware of STS-51 and the well-known "limits to inhibit" radio call. There's a million parts in that engine, and I have no clue how you're questioning the success of the design based on a bad batch of sensors from a random contractor. This is precisely why the engine is "human-rated" and has redundant backups, internal health monitoring, etc including the ability of the flight controller to inhibit automatic shut-downs of the remaining engines. Obviously it's a lot easier today with high-bandwidth data links and more elaborate plausibility protocols and engine management software, etc.

400+ "engine-missions" and a single in-flight failure on one of the most complex liquid-fueled rocket engines (and first reusable) ever made? A design out of the 70s? It's a spectacular piece of engineering, and your "with a different roll of the dice" comment is ridiculous. You're flying 1/4 million-pound aircraft into space - everything is a "calculated" roll of the dice.

To say that engine achieved a 99.7% reliability rating and a 100% mission-success rating (ie. most abort protocols require multiple engine failures anyways) speaks for itself.


These paragraphs can be summarized with three words: normalization of deviance.

You're taking a small sample size of data and reducing the outcome to "it didn't go boom." You're not considering how close to "boom" the SSME came on other missions. I used the phrase "roll of the dice" for a reason. The right SSME during STS-93 could have suffered catastrophic failure and loss-of-crew had the liberated LOX pin taken a different trajectory after it broke off.

I never said the SSME wasn't an amazingly high-efficiency machine. I never compared the SSME to anything SpaceX has developed. It doesn't particularly matter when they were developed. I am taking issue with the claim that they are "bulletproof." They aren't.
I have a three post per topic limit. You're welcome to have the last word.
 
angad84
Posts: 1978
Joined: Mon Nov 05, 2012 3:04 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Thu Mar 01, 2018 10:53 am

DfwRevolution wrote:
These paragraphs can be summarized with three words: normalization of deviance.

You're taking a small sample size of data and reducing the outcome to "it didn't go boom." You're not considering how close to "boom" the SSME came on other missions. I used the phrase "roll of the dice" for a reason. The right SSME during STS-93 could have suffered catastrophic failure and loss-of-crew had the liberated LOX pin taken a different trajectory after it broke off.

I never said the SSME wasn't an amazingly high-efficiency machine. I never compared the SSME to anything SpaceX has developed. It doesn't particularly matter when they were developed. I am taking issue with the claim that they are "bulletproof." They aren't.

Indeed. Read Feynman's appendix to the Rogers Commission Report, it's fantastic - https://science.ksc.nasa.gov/shuttle/mi ... ndix-F.txt
 
WIederling
Posts: 5904
Joined: Sun Sep 13, 2015 2:15 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Thu Mar 01, 2018 11:57 am

angad84 wrote:
DfwRevolution wrote:
These paragraphs can be summarized with three words: normalization of deviance.

You're taking a small sample size of data and reducing the outcome to "it didn't go boom." You're not considering how close to "boom" the SSME came on other missions. I used the phrase "roll of the dice" for a reason. The right SSME during STS-93 could have suffered catastrophic failure and loss-of-crew had the liberated LOX pin taken a different trajectory after it broke off.

I never said the SSME wasn't an amazingly high-efficiency machine. I never compared the SSME to anything SpaceX has developed. It doesn't particularly matter when they were developed. I am taking issue with the claim that they are "bulletproof." They aren't.

Indeed. Read Feynman's appendix to the Rogers Commission Report, it's fantastic - https://science.ksc.nasa.gov/shuttle/mi ... ndix-F.txt

cite:
"The Space Shuttle Main Engine was handled in a different manner,
top down, we might say. The engine was designed and put together all
at once with relatively little detailed preliminary study of the
material and components."

which could be seen as less surprising:
IMU the SSME is the licensed upscale from a design developed by Ludwig Bölkow in Germany ( and based on his patent ).

Final design of the SSME required fixing the detailing issues from scaling.
Murphy is an optimist
 
WIederling
Posts: 5904
Joined: Sun Sep 13, 2015 2:15 pm

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Thu Mar 01, 2018 11:58 am

Tugger wrote:
WIederling wrote:
estorilm wrote:
I mean if you had to be strapped to an engine (even near that thrust class) and sent into space, name ONE other design you'd feel safer on?


RD-107 family? :-)

Another great engine and design. :yes: But they are only half the rated trust of the RS-25 and are single use (


Actually the Vulcain II engine for the Ariane V main stage is up there too.
The new engine for the Ariane 6 seems to be a predominantly manufacturability evolution.
Murphy is an optimist
 
estorilm
Posts: 226
Joined: Fri Jan 16, 2009 3:07 am

Re: RS-25 Tested - SSME modified, upgraded for SLS - Beauty is a beast!

Thu Mar 01, 2018 2:52 pm

DfwRevolution wrote:
estorilm wrote:
I'm well aware of STS-51 and the well-known "limits to inhibit" radio call. There's a million parts in that engine, and I have no clue how you're questioning the success of the design based on a bad batch of sensors from a random contractor. This is precisely why the engine is "human-rated" and has redundant backups, internal health monitoring, etc including the ability of the flight controller to inhibit automatic shut-downs of the remaining engines. Obviously it's a lot easier today with high-bandwidth data links and more elaborate plausibility protocols and engine management software, etc.

400+ "engine-missions" and a single in-flight failure on one of the most complex liquid-fueled rocket engines (and first reusable) ever made? A design out of the 70s? It's a spectacular piece of engineering, and your "with a different roll of the dice" comment is ridiculous. You're flying 1/4 million-pound aircraft into space - everything is a "calculated" roll of the dice.

To say that engine achieved a 99.7% reliability rating and a 100% mission-success rating (ie. most abort protocols require multiple engine failures anyways) speaks for itself.


These paragraphs can be summarized with three words: normalization of deviance.

You're taking a small sample size of data and reducing the outcome to "it didn't go boom." You're not considering how close to "boom" the SSME came on other missions. I used the phrase "roll of the dice" for a reason. The right SSME during STS-93 could have suffered catastrophic failure and loss-of-crew had the liberated LOX pin taken a different trajectory after it broke off.

I never said the SSME wasn't an amazingly high-efficiency machine. I never compared the SSME to anything SpaceX has developed. It doesn't particularly matter when they were developed. I am taking issue with the claim that they are "bulletproof." They aren't.


How is the shuttle program a small sample size? The Merlin comes to mind because there's 5 of them each flight, but still - has exponentially fewer parts, less thrust and first flew 30 years later. Even then, with simple design and smaller thrust, the Merlin has had multiple catastrophic failures and the RS-25 has had zero. The RD-107 is indeed an incredible engine, though at half the thrust its design would have been incompatible with the shuttle and SLS designs, and has a bearing on reliability - in addition to being expendable.

Normalization of deviance doesn't apply when you're talking about a mind-boggling number of parts that all have to work perfectly or you get a "failure" and the statistical hit to match, yet again after over 400 "engine" missions, there was a single "failure" - those numbers speak for themselves, I don't know why you keep saying "well it almost blew up" - given the context of our discussion, that comment seems out of place. Normalization of deviance implies that every mission was a near failure and after 400+ engine flights, they just happened to remain lucky? Negative. You don't really get "lucky" with space programs, just ask the Russians about the N1. ;)

No one is mentioning that this is a staged-combustion / closed-loop design, in addition to a twin-shaft design with independent control of each turbo pump. There really isn't anything like this - the RD-180 is similar, though single-shaft, and had its first flight two decades after the RS-25 and is neither reusable nor human-rated.

And yes, though requiring significant overhauls and inspections - there were 405 engine launches (combined) and only 46 RS-25 engines ever built.

In summary - it's not a Honda Civic - you're going to have sensor/component faults, etc. and given its unprecedented design (first operational staged-combustion engine) human-rating, efficiency level, reusability, and era in which it was designed/developed, along with the fact that it achieved a 100 % mission success rate, factoring in complexity levels and variables.. personally, I believe this engine defines bullet-proof. In space flight context it's a relative term, not a blanket-statement.

Who is online

Users browsing this forum: cpd, petertenthije and 9 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos