Author Topic: RS-25 testing/development at Stennis for SLS - DISCUSSION  (Read 45402 times)

Online Chris Bergin

That was super!

Online DaveS

  • Shuttle program observer
  • Senior Member
  • *****
  • Posts: 7864
  • Sweden
  • Liked: 382
  • Likes Given: 14
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #81 on: 10/19/2017 08:06 PM »
Epic, certainly, but why on Earth are they firing this thing for so long? It will never approach this in flight.
500 seconds = 8.33 minutes, roughly how long they fired on a nominal shuttle ascent. So it is a perfectly valid test.
"For Sardines, space is no problem!"
-1996 Astronaut class slogan

"We're rolling in the wrong direction but for the right reasons"
-USA engineer about the rollback of Discovery prior to the STS-114 Return To Flight mission

Offline Stardust9906

  • Global Moderator
  • Full Member
  • *****
  • Posts: 1260
  • Durham, UK
  • Liked: 20
  • Likes Given: 903
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #82 on: 10/19/2017 08:14 PM »

Offline FutureSpaceTourist

  • Senior Member
  • *****
  • Posts: 6199
  • UK
    • Plan 28
  • Liked: 5654
  • Likes Given: 1615
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #83 on: 10/20/2017 03:02 PM »


Quote
Published on 19 Oct 2017
Engineers at NASA’s Stennis Space Center in Mississippi on Oct. 19 completed a hot-fire test of RS-25 rocket engine E2063, a flight engine for NASA’s new Space Launch System (SLS) rocket. Engine E2063 is scheduled to help power SLS on its Exploration Mission-2 (EM-2), the first flight of the new rocket to carry humans.

This video is available for download from NASA's Image and Video Library: https://images.nasa.gov/#/details-NAS...
« Last Edit: 10/20/2017 03:03 PM by FutureSpaceTourist »

Offline Hog

  • Full Member
  • ****
  • Posts: 1232
  • Woodstock
  • Liked: 314
  • Likes Given: 902
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #84 on: 06/20/2018 01:06 PM »
I just rewatched STS-31 Discover-HST on Youtube and I noticed something about the TAL abort calls.


At 35:35 of the video we get the "Droop Banjul-109" call meaning that Discovery could reach it's TAL site under 2 engine out conditions with a single SSME thrusting at 109%.
Then 40 seconds later, at about 36:15  we get the "Single engine Banjul 104" call, meaning that Discovery could now reach the Banjul TAL site in a 2 out case with a single engine thrusting at 104%.

I find it fascinating that a mere 5% of extra throttle, on a single RS-25 engine, can buy a crew/payload an extra 40 seconds of margin in reaching a Trans Atlantic Landing site back in the "Shuttle days".

Though this extra "throttle" won't be used to reach "Abort Sites" just imagine what a constant 109% throttle x 4 engines will do for SLS?  Extra push, when called for is never a bad thing.

Let's not forget the recent 113%RPL that one of the workhorse Development Engines- DE-0528 was tested at for 50 seconds of the 260 second test at Stennis back in Feb.

Article by Phillip Sloss about the test
https://www.nasaspaceflight.com/2018/02/rs-25-hot-fire-sls-engine-113-percent/
Paul

Offline johnfwhitesell

  • Full Member
  • ***
  • Posts: 301
  • Liked: 96
  • Likes Given: 191
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #85 on: 06/21/2018 04:21 AM »
If the engine goes up to 109% thrust, why dont they make that 100% thrust?  And why dont they just make 10 louder instead of adding 11?  And why wont these kids get off my lawn?

Online hopalong

  • Full Member
  • *
  • Posts: 110
  • Milton Keynes
  • Liked: 53
  • Likes Given: 36
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #86 on: 06/21/2018 05:14 AM »
If the engine goes up to 109% thrust, why dont they make that 100% thrust?  And why dont they just make 10 louder instead of adding 11?  And why wont these kids get off my lawn?

Short answer - Mission Planning.
The SSME increased in thrust after its introduction into service, but the missions were based on the baseline thrust (100%), so to avoid confusion about which '100%' the engines were rated at, they kept the same baseline thrust rate as 100% and the up rated engines ran at 104% on the normal missions and 109% on an abort.

Offline daveklingler

  • Full Member
  • ****
  • Posts: 502
  • Liked: 151
  • Likes Given: 16
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #87 on: 07/10/2018 02:39 PM »
There's something I've wondered about for the past 10- or 15-odd years, and maybe someone here knows the answer.

The SSME underwent many years of development, some of it at the hands of Pratt engineers who were asked to come in and quietly fix Rocketdyne's design issues, and some of it by engineers who came well after.  The AR-22 seems to provide evidence that the RS-25 is a much better engine than the one that first flew in 1981.

IIRC, the downcomer was next on the redesign list when SSME production was discontinued. Does someone know whether PWR just picked up where they'd left off?  I know it's far more reliable now, but how much? How close is the RS-25 to its original reuseability design goals?

Online whitelancer64

There's something I've wondered about for the past 10- or 15-odd years, and maybe someone here knows the answer.

The SSME underwent many years of development, some of it at the hands of Pratt engineers who were asked to come in and quietly fix Rocketdyne's design issues, and some of it by engineers who came well after.  The AR-22 seems to provide evidence that the RS-25 is a much better engine than the one that first flew in 1981.

IIRC, the downcomer was next on the redesign list when SSME production was discontinued. Does someone know whether PWR just picked up where they'd left off?  I know it's far more reliable now, but how much? How close is the RS-25 to its original reuseability design goals?

The SSME went through several iterations. FMOF [First Manned Orbital Flight] (1981), Phase I (1983), Phase II (1988), Block I (July 1995), Block IA (Oct. 1995), Block IIA (1998), and Block II (2001).

I'm of the understanding, but someone else will probably correct me, that all SSMEs Block I and later could be full-duration fired multiple times with little more than borescope inspections.
"One bit of advice: it is important to view knowledge as sort of a semantic tree -- make sure you understand the fundamental principles, ie the trunk and big branches, before you get into the leaves/details or there is nothing for them to hang on to." - Elon Musk
"There are lies, damned lies, and launch schedules." - Larry J

Offline russianhalo117

  • Senior Member
  • *****
  • Posts: 4460
  • AR USA / Berlin, DE / Moscow, RF
  • Liked: 1056
  • Likes Given: 573
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #89 on: 07/10/2018 03:30 PM »
There's something I've wondered about for the past 10- or 15-odd years, and maybe someone here knows the answer.

The SSME underwent many years of development, some of it at the hands of Pratt engineers who were asked to come in and quietly fix Rocketdyne's design issues, and some of it by engineers who came well after.  The AR-22 seems to provide evidence that the RS-25 is a much better engine than the one that first flew in 1981.

IIRC, the downcomer was next on the redesign list when SSME production was discontinued. Does someone know whether PWR just picked up where they'd left off?  I know it's far more reliable now, but how much? How close is the RS-25 to its original reuseability design goals?
The RS-24 demonstrator engine served as the basis for the operational RS-25. It was originally conceived as expendable but switched to reusable design for the STS programme.

Online AncientU

  • Senior Member
  • *****
  • Posts: 6175
  • Liked: 3964
  • Likes Given: 5459
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #90 on: 07/11/2018 12:39 AM »
Great engine... huge effort to make it truly resuable. 
So, could someone explain to me again why we are throwing four of them away each flight?
"If we shared everything [we are working on] people would think we are insane!"
-- SpaceX friend of mlindner

Offline ulm_atms

  • Rocket Junky
  • Full Member
  • *
  • Posts: 146
  • To boldly go where no government has gone before.
  • Calhoun, LA
  • Liked: 126
  • Likes Given: 54
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #91 on: 07/11/2018 01:22 AM »
Great engine... huge effort to make it truly resuable. 
So, could someone explain to me again why we are throwing four of them away each flight?

To funnel more money to AR?  8)

I kid but it is because this engine was/is the most powerful engine they had at the time when designing SLS and they were trying to do it on the "cheap"....so no engine development money was available.  I do hate seeing that beautiful engine being thrown away though.

I know you knew the answer when you asked however... ;)

Edit: Forgot words...Twice...I'm tired... :-[
« Last Edit: 07/11/2018 01:35 AM by ulm_atms »

Offline johnfwhitesell

  • Full Member
  • ***
  • Posts: 301
  • Liked: 96
  • Likes Given: 191
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #92 on: 07/11/2018 03:18 AM »
I do hate seeing that beautiful engine being thrown away though.

I wonder how much it would cost to develop a SMART system (like Vulcan) to recover them.  They shouldn't even wait for SLS to start trying.  Just make some dummies and put the dummies on a Vega as the payload then try to parachute the dummies.  Vega's only cost 37 million so it should be a lot cheaper then throwing away 4 of those beauties.

But more seriously, it's pretty damn infuriating that they are yanking bits out of the old space shuttles for the SLS.  It's like looting the Parthenon for marble.  If they are going to throw away RS-25s, they should throw away the ones that are made for a single use.  They've had plenty of time to get them ready.

Offline daveklingler

  • Full Member
  • ****
  • Posts: 502
  • Liked: 151
  • Likes Given: 16
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #93 on: 07/12/2018 10:49 PM »
I do hate seeing that beautiful engine being thrown away though.

I wonder how much it would cost to develop a SMART system (like Vulcan) to recover them. 

It may be that Phantom Express will prove to be as helpful to the RS-25's continued existence as SLS. If Phantom Express proves the engine's a safe design choice for reusable vehicles with rapid turnaround, it may pick up other design wins.

Maybe Phantom Express is a smarter recovery system than SMART.  :)

Quote
They shouldn't even wait for SLS to start trying.  Just make some dummies and put the dummies on a Vega as the payload then try to parachute the dummies.  Vega's only cost 37 million so it should be a lot cheaper then throwing away 4 of those beauties.

I confess that I have the attitude toward SMART that many people have after watching a whole bunch of F9 landings: "Huh?"

Quote
But more seriously, it's pretty damn infuriating that they are yanking bits out of the old space shuttles for the SLS.  It's like looting the Parthenon for marble.  If they are going to throw away RS-25s, they should throw away the ones that are made for a single use.  They've had plenty of time to get them ready.

I go back and forth. On the one hand, those are museum pieces.  On the other hand, they're rocket engines, and deserve to be pushing payloads.  On the gripping hand, they're being thrown away????!!!!!!

Offline daveklingler

  • Full Member
  • ****
  • Posts: 502
  • Liked: 151
  • Likes Given: 16
Re: RS-25 testing/development at Stennis for SLS - DISCUSSION
« Reply #94 on: 07/12/2018 11:01 PM »
There's something I've wondered about for the past 10- or 15-odd years, and maybe someone here knows the answer.

The SSME underwent many years of development, some of it at the hands of Pratt engineers who were asked to come in and quietly fix Rocketdyne's design issues, and some of it by engineers who came well after.  The AR-22 seems to provide evidence that the RS-25 is a much better engine than the one that first flew in 1981.

IIRC, the downcomer was next on the redesign list when SSME production was discontinued. Does someone know whether PWR just picked up where they'd left off?  I know it's far more reliable now, but how much? How close is the RS-25 to its original reuseability design goals?

The SSME went through several iterations. FMOF [First Manned Orbital Flight] (1981), Phase I (1983), Phase II (1988), Block I (July 1995), Block IA (Oct. 1995), Block IIA (1998), and Block II (2001).

I'm of the understanding, but someone else will probably correct me, that all SSMEs Block I and later could be full-duration fired multiple times with little more than borescope inspections.

Thanks to you and RussianHalo117.  If that's the case, which is certainly implied by its use in Phantom Express, I'm really looking forward to watching it finally do what it's capable of doing, sigh...even though it's an expensive alternative to a BE-4 or maybe even an AR-1.  In a way, Phantom Express is somewhat like a Shuttle 2.0, a little more-so than Dream Chaser or X-37b.  RS-25 is the late-blooming, somewhat homelier half-sister to the high-pressure hydrolox engines that Pratt developed during the 1960's for passenger use.

Maybe there will be a cost-competitive, scaled-up version of Phantom Express some day with a reusable first stage, designed to be a "space truck".  :)
« Last Edit: 07/12/2018 11:04 PM by daveklingler »

Offline wannamoonbase

  • Elite Veteran
  • Senior Member
  • *****
  • Posts: 3011
  • Denver, CO
    • U.S. Metric Association
  • Liked: 691
  • Likes Given: 1150
Great engine... huge effort to make it truly resuable. 
So, could someone explain to me again why we are throwing four of them away each flight?

To funnel more money to AR?  8)

I kid but it is because this engine was/is the most powerful engine they had at the time when designing SLS and they were trying to do it on the "cheap"....so no engine development money was available.  I do hate seeing that beautiful engine being thrown away though.

I know you knew the answer when you asked however... ;)

Edit: Forgot words...Twice...I'm tired... :-[

The RS-25 is an incredible engine with a long history and great performance stats.  But it is 40+ year old technology at this time.

Throwing away 4 of these expensive wonder machine with each SLS launch is an expensive endeavor.

However, SLS has such a slow and long manifest there won't be too many flights.  (Until the public forces congress to adopt cheaper commercial alternatives.)
SpaceX, just a few things planned for 2018: FH, Starlink Prototypes, Block 5, Dragon 2, Increased launch rate.

Offline johnfwhitesell

  • Full Member
  • ***
  • Posts: 301
  • Liked: 96
  • Likes Given: 191
I confess that I have the attitude toward SMART that many people have after watching a whole bunch of F9 landings: "Huh?"

Vertical landing is the best solution... if you are landing 20 times a year.  The SLS wont be anywhere close to that.

Also for Falcon 9 vertical landing makes more sense because of how early the separation is.  Falcon 9 has a heavy second stage with RP-1 instead of the LH2.  SLS has LH2 in the first stage as well as the second stage plus it has those massive boosters.  All that adds up to the SLS first stage needs to be going pretty darn fast to do it's job so a vertical landing would be tough.

Tags: