notes on the L2 SLS section [...] have revealed a Block 1B configuration, one that continues to use RSRMV (solid) boosters, an 8.4m core with four RS-25D/E engines, an 8.4m Cryogenic Propulsion Stage with four RL10A-4-2 engines, and either an Orion MPCV or a payload under a 8.4m fairing. This vehicle would also be aiming to launch 105mt to LEO. However, the new stage can perform part of the ascent as well as TLI (Trans Lunar Injection).The notes add that there are enough RS-25D engines in stock to support four missions, and enough RSRMV material (casings, etc.) to support 10 missions.Selecting the SLS Block 1B over the Block 1A would result in delaying the advanced boosters until the 2030s, depending on the flight rate that is to be determined by the currently undefined Exploration Roadmap.
I'm curious, in Chris's article, it states there are enough SRB material to support 10 missions. Does that mean using the existing 4 seg material for the new 5 seg boosters?
Quote from: Khadgars on 12/21/2012 01:17 amI'm curious, in Chris's article, it states there are enough SRB material to support 10 missions. Does that mean using the existing 4 seg material for the new 5 seg boosters?My understanding is yes. There are at least 100 casing segments available, but less than 110. Two boosters X 5 casings each = 10 casings per launch x 10 launches = 100 casings required. This is casing, not propellant. The casings are refurbished and refilled. My understanding is that the internal configuration of the propellant differs between the 4 segment STS booster and the 5 segment Ares/SLS booster.
Quote from: TomH on 12/21/2012 03:36 amThere are at least 100 casing segments available [...] The casings are refurbished and refilled.I thought the SRBs for the SLS is not going to be recovered?
There are at least 100 casing segments available [...] The casings are refurbished and refilled.
My understanding is that the internal configuration of the propellant differs between the 4 segment STS booster and the 5 segment Ares/SLS booster.
Thought it might be prudent to create a thread for the SLS Block 1B since it often strays off topic in others. After hearing lots of discussions about other variants it seems like this is the most straight forward path to creating the most capable LV. How much more cost effective is it when compared to the 1A? Does it free up enough funding for other payloads?-Khad
So 1B means a delay in any competitive procurement for SLS. The upper stage would be designed and built under the Boeing "stages" contract. RS-25 engines would come from PWR; there is no other supplier. Ditto (presumably) for RL-10 engines. RSRMV can only come from ATK. Only 1A involves a competitive procurement of an "advanced" booster. (I place "advanced" in scare quotes because IMHO it would be fine if ATK offered new steel cases for additional boosters.)But maybe you wanted to discuss 1B without discussing how it would be procured?
Yea, I’ve wondered why NASA seems to be putting so much money/time into both Block 1B and 1A. If the advanced boosters would be put off so far, why award the study contracts for advanced liquid boosters they have? Seems like they’d wait until they’ve finished their evaluations on which path forward before they started doing that.But maybe there’s some organizational reason they need to pursue 1A to a certain point, and those awards are a part of that?
Anyway, just wild speculation here, if they go with Block 1B, I figure liquid advanced boosters would be put off for like 10 years, while they develop the 1B stage.
I thought the SRBs for the SLS is not going to be recovered?
I think it makes sense to quote the article Chris Bergin wrote regarding the definition of "Block 1B."Quotenotes on the L2 SLS section [...] have revealed a Block 1B configuration, one that continues to use RSRMV (solid) boosters, an 8.4m core with four RS-25D/E engines, an 8.4m Cryogenic Propulsion Stage with four RL10A-4-2 engines, and either an Orion MPCV or a payload under a 8.4m fairing. This vehicle would also be aiming to launch 105mt to LEO. However, the new stage can perform part of the ascent as well as TLI (Trans Lunar Injection).The notes add that there are enough RS-25D engines in stock to support four missions, and enough RSRMV material (casings, etc.) to support 10 missions.Selecting the SLS Block 1B over the Block 1A would result in delaying the advanced boosters until the 2030s, depending on the flight rate that is to be determined by the currently undefined Exploration Roadmap.....
Quote from: sdsds on 12/21/2012 12:55 amI think it makes sense to quote the article Chris Bergin wrote regarding the definition of "Block 1B."Quotenotes on the L2 SLS section [...] have revealed a Block 1B configuration, one that continues to use RSRMV (solid) boosters, an 8.4m core with four RS-25D/E engines, an 8.4m Cryogenic Propulsion Stage with four RL10A-4-2 engines, and either an Orion MPCV or a payload under a 8.4m fairing. This vehicle would also be aiming to launch 105mt to LEO. However, the new stage can perform part of the ascent as well as TLI (Trans Lunar Injection).The notes add that there are enough RS-25D engines in stock to support four missions, and enough RSRMV material (casings, etc.) to support 10 missions.Selecting the SLS Block 1B over the Block 1A would result in delaying the advanced boosters until the 2030s, depending on the flight rate that is to be determined by the currently undefined Exploration Roadmap.....Why "an 8.4m Cryogenic Propulsion Stage with four RL10A-4-2 engines" and not six RL10A-4-2 engines like the J-246SH? Will the four RL10A-4-2 engines eventually be replaced by four RL-60s/MB-60s or four Next Generation Engines?
They could probably avoid the need for J-2X engines on the second stage that way if Mars missions required some serious performance upgrades (provided the boosters are upgraded).
A misconception is occuring here. One of the 4 segments cassings of the SRB is a specialized cassing that goes only on the bottom. The other three are basiclly interchangable. So with 104 casings a set of 26 total 4 segment boosters, there are 26 specialized nozzel segments and 78 generic segments. That is only enough generic segments to create 19 complete 5 segment boosters or 9 flight sets of 2 (one spare booster).Another 4 segment booster added to the total a 27th booster for a total of 108 segments would allow the creation of 20 5 segment boosters. Normally these guys come in pairs not singles.9 flights would be one flight 2017 another in 2019 and then 1 per year through 2026. A new advanced SRB or LRB development must (using NASA's long development cycle of 8 years for such things) start in 2018 to allow for flights in 2027. From a budget point of veiw easily doable. A side note is that four more sets of flight hardware can be done if 10 generic steel casings are manufactured before 2026 (there are four additional sets of nozzel cassings and caps not used with the first 9 sets of 5 segment SRB's as well as 6 generic cassings not used), alowing flights through 2030.
Quote from: Hyperion5 on 12/22/2012 09:10 pmThey could probably avoid the need for J-2X engines on the second stage that way if Mars missions required some serious performance upgrades (provided the boosters are upgraded).I keep seeing this point come up over and over again - using the RL-10 and derivatives to power the upper stage of the SLS as was recommended by Direct, but after investing millions and millions of dollars developing J-2X, which I have the impression of being a powerful and capable rocket engine, why on earth wouldn't NASA want to use it for the upper stage of the SLS?
Well, as I understand it (which could be wrong) the J2X is really a 2nd stage engine powerful enough and designed to do a significant amount of the ascent through the atmosphere.
As I understand it, the vehicle is pretty much in vacuum by the time the J-2 kicks in, but it is still fighting gravity losses, so velocity rather than atmosphere seems to be the variable. Remember that the S-IV on Saturn I had 6 RL-10s with a total of 90k lb. thrust and ISP of 410. The Saturn I could put 19,800 lb. in LEO. The S-IV was replaced with the S-IVB which had a single J-2 @ 232K lb. thrust @ ISP of 421 and could place 41,000 lb. in LEO. On Saturn I-B the single J-2 on the S-IVB was able to place well more than twice the payload to LEO as 6 RL-10s on the S-IV of the Saturn I.<additional helpful stuff that's truncated for reasons of length>
Read this:http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20110015783_2011016690.pdf
Quote from: RotoSequence on 12/23/2012 02:25 amQuote from: Hyperion5 on 12/22/2012 09:10 pmThey could probably avoid the need for J-2X engines on the second stage that way if Mars missions required some serious performance upgrades (provided the boosters are upgraded).I keep seeing this point come up over and over again - using the RL-10 and derivatives to power the upper stage of the SLS as was recommended by Direct, but after investing millions and millions of dollars developing J-2X, which I have the impression of being a powerful and capable rocket engine, why on earth wouldn't NASA want to use it for the upper stage of the SLS?Well, as I understand it (which could be wrong) the J2X is really a 2nd stage engine powerful enough and designed to do a significant amount of the ascent through the atmosphere. It's almost 300K lbs of thrust, and weighs 2.5mt. The RL-10 is a higher isp engine, lighter, and better for in-space propulsion where isp is king, and not a lot of thrust is needed.
But...if they go with a Block 1B stage as the PoR for a decade or more, [J-2X is] just not need, nor even a good choice. It'd work, but RL-10, which exists and in current production, is a -better- choice. The'd probably have to throttle it down so it wouldn't accelerate too fast.RL-10 will cost share with USAF as well.
Quote from: Lobo on 12/23/2012 02:56 amWell, as I understand it (which could be wrong) the J2X is really a 2nd stage engine powerful enough and designed to do a significant amount of the ascent through the atmosphere.As I understand it, the vehicle is pretty much in vacuum by the time the J-2 kicks in, but it is still fighting gravity losses, so velocity rather than atmosphere seems to be the variable. Remember that the S-IV on Saturn I had 6 RL-10s with a total of 90k lb. thrust and ISP of 410. The Saturn I could put 19,800 lb. in LEO. The S-IV was replaced with the S-IVB which had a single J-2 @ 232K lb. thrust @ ISP of 421 and could place 41,000 lb. in LEO. On Saturn I-B the single J-2 on the S-IVB was able to place well more than twice the payload to LEO as 6 RL-10s on the S-IV of the Saturn I.Even on Saturn V, the S-IVB still had to contribute a Delta Vee of over 3000 mph to reach temporary parking orbit before its restart as an EDS, so during that first burn, it was fighting more severe gravity losses than during its TLI burn.I think the main issue on the Saturn I-B version of the S-IVB is that as an US, its purpose was to reach LEO, not to be an EDS. The single J-2 was able to fight gravity loss much better than the combined 6 RL-10s. On lunar mission Saturn Vs, if the S-II had been able to place the payload into LEO, perhaps the third stage could have employed an RL-10 as that EDS would not have to fight gravity loss very much during TLI.
It seems to me that what has not been well defined on SLS is whether a second stage would be used A.) solely for reaching LEO.B.) solely as an EDS.C.) as a restartable stage which has a substantial first burn to reach LEO prior to a 2nd (Earth Departure) burn.D.) as a restartable stage which has a short first burn for circularization prior to a 2nd (Earth Departure) burn.If the objective is A or C, then the J-2X (ISP 448) would seem better in fighting gravity losses. If the objective is B or D, then the RL-10B2 (ISP 462) has a 14 sec ISP advantage.
This was to the detriment of the engine's use on the Ares V US. Again, if memory is correct, when CxP was cancelled, but J-2X kept alive, there was some discussion about reversing those parameters to that in its use primarily as an Earth Departure engine, J-2X could be pushed back to its earlier specs with a higher ISP. If anyone has details on this, please advise.
Elsewhere Quote from: edkyle99 on 01/27/2012 01:42 pm Ed Kyle has made a compelling case for an SLS derived launcher with a single J-2X powering an appropriately sized middle stage topped by a DIVH derived iCPS. For a single launch that's going to be difficult to beat. The engine count is low (leading to high reliability) and the performance would be darn awful good.
Quote from: Lobo on 12/23/2012 02:56 amWell, as I understand it (which could be wrong) the J2X is really a 2nd stage engine powerful enough and designed to do a significant amount of the ascent through the atmosphere.As I understand it, the vehicle is pretty much in vacuum by the time the J-2 kicks in, but it is still fighting gravity losses, so velocity rather than atmosphere seems to be the variable..............Even on Saturn V, the S-IVB still had to contribute a Delta Vee of over 3000 mph to reach temporary parking orbit before its restart as an EDS, so during that first burn, it was fighting more severe gravity losses than during its TLI burn.
Of course any discussion of an upper stage must consider what booster is being used: 5-seg solid, ATK adv. SRB, AJ adv. LRB, Dynetics adv. LRB. ATK just said their advanced SRB could not meet the high profile Mars objectives unless the core uses 5 RS-25Es. The latest from NASA was an intent always to use 4 RS-25s on the core. The more powerful Dynetics booster may have the ability to make any US purely an EDS, thereby enabling a low number of RL-10B2s.
So basically the Bloc II SLS could simply be an SLS Bloc IB with Dynetics or Aerojet boosters and still be hugely capable. That's a very nice evolution path for NASA given how much less expense it'd require versus developing an enlarged core or an all-new stage. Perhaps ATK will have more difficulties selling NASA on advanced SRBs than I thought.
the reliability vs the 4-engine CPS currently envisioned on the SLS Bloc IB is likely to be lower
the core stage is nearly at orbital speed when stage separation would occur.
Quote from: Hyperion5 on 12/25/2012 12:14 amthe core stage is nearly at orbital speed when stage separation would occur. True for Block I. But for Block IB? The attached (crudely drawn) map shows an alternative. Launching to an orbit with a 28.5 degree inclination the Block I core might end up in the Pacific, as did the external tanks for Shuttle launches to Hubble. That's shown as the red marker with the square. I assert without proof that for Block IB, mass sent through TLI would be greater if the core were dropped in the Indian Ocean (plain red marker) with some CPS propellant used to reach orbit.
Quote from: sdsds on 12/25/2012 06:03 amQuote from: Hyperion5 on 12/25/2012 12:14 amthe core stage is nearly at orbital speed when stage separation would occur. True for Block I. But for Block IB? The attached (crudely drawn) map shows an alternative. Launching to an orbit with a 28.5 degree inclination the Block I core might end up in the Pacific, as did the external tanks for Shuttle launches to Hubble. That's shown as the red marker with the square. I assert without proof that for Block IB, mass sent through TLI would be greater if the core were dropped in the Indian Ocean (plain red marker) with some CPS propellant used to reach orbit.Well obviously Bloc IB is going to stage lower and slower than Bloc I due to having a bigger stage up top and probably a bigger payload. I would think the Indian Ocean would be a quite reasonable place for the core to drop. Add some LRBs onto the Bloc IB to make it the Bloc 2 and we may see the core drop into the Pacific once again unless it's a particularly heavy payload.
Quote from: Hyperion5 on 12/25/2012 06:23 amWell obviously Bloc IB is going to stage lower and slower than Bloc I due to having a bigger stage up top and probably a bigger payload."CPS Gamma" with "5x MB-60" Page 29From: A Study of CPS Stages for Missions beyond LEO By Mark Schaffer May 16, 2012
Well obviously Bloc IB is going to stage lower and slower than Bloc I due to having a bigger stage up top and probably a bigger payload.
Quote from: HappyMartian on 12/25/2012 08:10 amQuote from: Hyperion5 on 12/25/2012 06:23 amWell obviously Bloc IB is going to stage lower and slower than Bloc I due to having a bigger stage up top and probably a bigger payload."CPS Gamma" with "5x MB-60" Page 29From: A Study of CPS Stages for Missions beyond LEO By Mark Schaffer May 16, 2012Schaffer's work is great, but his CPS Gamma is going to be a long way out on the timeline. As you suggest, he assumes something else put a bunch of propellant into orbit! Back as 2011 others at NASA suggested an iCPS-2. It would carry 57.8 tonnes of usable propellant, compared with iCPS-1 which is reported as carrying 27.2 tonnes.If I understand that plan correctly, the core would deliver iCPS-1 and payload into a -87 km x 241 km target orbit. After coasting to apogee, iCPS-1 would provide the 100 m/s orbit circularization delta-v.In contrast, I'm estimating the core could deliver iCPS-2 and payload into an orbit that requires a circularization delta-v of about 700 m/s.I'm sensitive to the "garbage in, garbage out" criticism, but my estimates are that iCPS-1 would deliver 36 tonnes through TLI and iCPS-2 would deliver 41 tonnes.In both cases I assumed the iCPS Isp was 462 s, like RL10. J2X is never going to have an Isp like that. So I used what seemed like a worst case: 438 s. But I also assumed it had enough thrust to contribute more than just a circularization burn; indeed I assumed it provided 1250 m/s of ascent delta-v. The propellant mass of the stage would grow to 89 tonnes, but even with its poor Isp, it still looks like it delivers 42 tonnes through TLI.These results suggest that for an SLS second stage, having enough engine thrust to materially participate in ascent can overcome even a fairly severe Isp penalty.
A J-2X doesn't provide more than four starts. Two starts would be the norm.
A single J-2X doesn't provide engine out capability.
A J-2X isn't capable of small and precise correction burns
A J-2X Isp (vac.) 448 seconds is less
Our most likely choice becomes the MB-60
I'm sensitive to the "garbage in, garbage out" criticism, but my estimates are that iCPS-1 would deliver 36 tonnes through TLI and iCPS-2 would deliver 41 tonnes.
Quote from: sdsds on 12/27/2012 08:29 amI'm sensitive to the "garbage in, garbage out" criticism, but my estimates are that iCPS-1 would deliver 36 tonnes through TLI and iCPS-2 would deliver 41 tonnes.Oops! I somehow allowed "iCPS-1" to hold way too much propellant. (The 5m Delta stage holds only 27 tonnes.) But I'm pleased to see the 41 tonne through TLI estimate for "iCPS-2" is more or less validated by Jim Chilton's October 18, 2012 presentation. (Thanks to Steven Pietrobon for the link: https://info.aiaa.org/Regions/SE/HSV_AIAA/Downloadable%20Items/AIAA-Chilton_18Oct2012_Final2.pdf)Chilton shows 43 tonnes through TLI for this configuration.
Actually I think "Beyond Earth Orbit" means beyond the earth's gravity entirely. If, as I suspect, they mean that's the maximum escape velocity payload, then the TLI number should be around 45 mt according to Lobo, a near exact match for the Saturn V. Only the later Saturn Vs, which were optimized for greater TLI mass in order to carry the lunar rover (Apollo 15-17), surpassed 45 mt through TLI. They pushed 47 mt through TLI. While it doesn't surpass the Saturn V, clongton was right that the IB could single-launch Apollo missions, or at least the early ones. I know it's bigger than what he wants, but I say, heck, if we're going to have a big launcher, we might as well get more than just 70 mt to LEO & 19 mt BEO out of it.
Quote from: sdsds on 12/27/2012 08:29 amQuote from: HappyMartian on 12/25/2012 08:10 amQuote from: Hyperion5 on 12/25/2012 06:23 amWell obviously Bloc IB is going to stage lower and slower than Bloc I due to having a bigger stage up top and probably a bigger payload."CPS Gamma" with "5x MB-60" Page 29From: A Study of CPS Stages for Missions beyond LEO By Mark Schaffer May 16, 2012Schaffer's work is great, but his CPS Gamma is going to be a long way out on the timeline. As you suggest, he assumes something else put a bunch of propellant into orbit! Back as 2011 others at NASA suggested an iCPS-2. It would carry 57.8 tonnes of usable propellant, compared with iCPS-1 which is reported as carrying 27.2 tonnes.If I understand that plan correctly, the core would deliver iCPS-1 and payload into a -87 km x 241 km target orbit. After coasting to apogee, iCPS-1 would provide the 100 m/s orbit circularization delta-v.In contrast, I'm estimating the core could deliver iCPS-2 and payload into an orbit that requires a circularization delta-v of about 700 m/s.I'm sensitive to the "garbage in, garbage out" criticism, but my estimates are that iCPS-1 would deliver 36 tonnes through TLI and iCPS-2 would deliver 41 tonnes.In both cases I assumed the iCPS Isp was 462 s, like RL10. J2X is never going to have an Isp like that. So I used what seemed like a worst case: 438 s. But I also assumed it had enough thrust to contribute more than just a circularization burn; indeed I assumed it provided 1250 m/s of ascent delta-v. The propellant mass of the stage would grow to 89 tonnes, but even with its poor Isp, it still looks like it delivers 42 tonnes through TLI.These results suggest that for an SLS second stage, having enough engine thrust to materially participate in ascent can overcome even a fairly severe Isp penalty.A J-2X doesn't provide more than four starts. Two starts would be the norm.A single J-2X doesn't provide engine out capability. A J-2X isn't capable of small and precise correction burns to adjust TLI or other mission delta-v corrections. This implies the need for a smaller rocket engine. A J-2X Isp (vac.) 448 seconds is less than the MB-60 Isp (vac.) 465, or RL10-A4-2 Isp (vac.) 451 sec.The RL10-A4-2 isn't powerful enough unless we go to twenty engines and that would not fit under the CPS. The NGE isn't powerful enough unless we go to ten engines and that would be difficult to fit under the CPS. Our most likely choice becomes the MB-60 which is a modern, compact, and efficient rocket engine and has a useful thrust of 60,000 lbf. Five MB-60s give 300,000 lbs of thrust which is slightly more than the 294,000 pounds of thrust of the J-2X. Five MB-60s, with multiple restarts, also allow for engine out capability, and the ability to make precise small delta-v corrections for TLI, TMI, or other missions. The CPS as arrives in LEO with a payload and almost no propellant. Hopefully all the claims about hydrolox transfers and LEO propellant depots or buddy tankers are accurate and we will be able to fill the CPS with propellant. Note that the largest CPS without a payload might also serve as a tanker once it is in Lunar orbit and enable multiple flights of a hydrolox reusable Lander. The largest CPS perhaps could also ferry itself back to a high Earth orbit or LEO to be resupplied with propellant for another mission. The main disadvantage of the five MB-60s versus the J-2X is additional engine weight. A J-2X is about: 5,450 pounds (2,470 kg)A MB-60 is about: 1,302 pounds (591 kg )For various versions of the MB-60 CPS see Page 33 of: From: A Study of CPS Stages for Missions beyond LEO By Mark Schaffer May 16, 2012At: http://spirit.as.utexas.edu/~fiso/telecon/Schaffer_5-16-12/Schaffer_5-16-12%20Rev%20A.pdfAlso at: http://www.sei.aero/eng/papers/uploads/archive/SpaceWorks%20CPS%20Study%20Final%20Distribution.pdf
I think the availability of SRB motor casings and RS-25 engines will determine the fate of 1B, and likely the fate of the US HLLV program for many years to come.I hope the powers that be are really looking to Block 1 as a bridge to the preferred LRB + RS-68 powered 8.4 meter core, but in doing this, we run the risk of scuttling the whole deal...That is, would it have been better to take longer to do it right (and risk the prolonged downtime killing the whole effort), or to keep elements flying, however infrequently, to keep the HLLV dream alive (and risk the costs of the interim program killing the whole effort). ATK lobbying clearly has played a big role, and will continue to.
It seems that the "ICPS-2" moniker came from somewhere outside this thread, but it does not correctly describe the proposed 4xRL10 stage, which would not use ICPS tank tooling (it would have 8.4 m ET diameter and 5.5 m Ares I diameter tanks) or engines (or avionics).
Do we think they are even going to go with the 105 ton/1B configuration and not skip right to 2?
Quote from: PahTo on 03/11/2013 01:21 pmActually, the RS-68 won't work with SRBs due to heating. I envision a 2x RS-68 with LRBs as the preferred solution for safety, cost and eficiency. Now that we're firmly on the Block 1 (SRB) path, infrastructure is going in that makes going away from SRBs (either 5-seg or "Advanced") a more costly (and difficult) proposition.This makes the 1B seem like the long term solution, but there are major hurdles, not the least of which is development of the RS-25E. The current batch of SSME will run out. Hence my comment about engine availability.Just building more SSMEs, perhaps while adopting small production efficiency changes, is an option. The low flight rate means that current SSMEs will last until 10-15 years from now, so steady slow build rates of an already developed engine are certainly an option.Same goes for SRB casings. Those on hand will last for many years. In the interim, either a move could be made to composite casings or more steel casings could be fabricated. - Ed Kyle
Actually, the RS-68 won't work with SRBs due to heating. I envision a 2x RS-68 with LRBs as the preferred solution for safety, cost and eficiency. Now that we're firmly on the Block 1 (SRB) path, infrastructure is going in that makes going away from SRBs (either 5-seg or "Advanced") a more costly (and difficult) proposition.This makes the 1B seem like the long term solution, but there are major hurdles, not the least of which is development of the RS-25E. The current batch of SSME will run out. Hence my comment about engine availability.
Quote from: Lobo on 03/11/2013 05:59 pmPah, I think switching to two RS-68A’s could work in place of the four RS-25’s, but that’s require a full redesign of the MPS on the core, as well as man-rating of the RS-68A. Going to RS-68 would mean losing a lot of payload capability. RS-68 is a first stage engine. The SLS core stage is a long-burn "sustainer" type stage that wants high specific impulse. SSME ISP is 455 sec. RS-68 is 407 sec. The math doesn't work, unless one is willing to give up 20 or more tonnes of payload capability. - Ed Kyle
Pah, I think switching to two RS-68A’s could work in place of the four RS-25’s, but that’s require a full redesign of the MPS on the core, as well as man-rating of the RS-68A.
I thought base heating issues prevent the RS-68A from being used with the big SRBs (performance notwithstanding). Wouldn't the use of LRBs "make up" for the performance issue by way of altering the burn time for the RS-68 (as well as being higher Isp than SRBs)?
According to the Direct V1 paper, RS-68 regen has a vacuum Isp of 435 s and 5% increased thrust. There was some FUD disputing that value, but this value is correct, as it assumes a design correction implemented in the RS-68A which has an Isp of 414 s.
I don’t think it’ll ever be known, since I’m sure the NASA team working on Ares V only evaluated configurations applicable to Ares V, but I’m of the mind that if you had a two RS-68 core, with no engines under the outline of the core, and none too close to the SRB’s nozzles, and placed at 90 degrees to the SRB’s with tapered flairs so that air can move around them, that LV could perhaps be viable with ablative RS-68’s. Basically, I think maybe a Jupiter-120 could have actually worked, where Ares V ran into problems with the different base heating environment. A Jupiter-232 might have run into a similar problem with the central engine being trapped under the core with SRB’s or other RS-68’s burning on all sides of it. And that’s what I was sort of going with, with two RS-68A’s in place of the four SLS RS-25’s. No way to know for sure, but I’d be very curious to know and see that modeled.
The primary benefit of a regeneratively cooled nozzle RS-68 would be reduced weight (RS-68 is a heavy engine), with some incremental improvement in specific impulse possible, but it would never approach the efficiency of a staged combustion SSME. Think 410-415 sec at most, IMO, though PWR once projected 418 sec as a possible design goal.A regen RS-68 would cost more than standard RS-68 too. An alternative would be six or seven Vulcain 2 or J-2S type engines on the core. They would produce as much thrust as four SSMEs at better ISP than RS-68, but without requiring the staged combustion cycle. - Ed Kyle
Quote from: edkyle99 on 03/12/2013 10:35 pmThe primary benefit of a regeneratively cooled nozzle RS-68 would be reduced weight (RS-68 is a heavy engine), with some incremental improvement in specific impulse possible, but it would never approach the efficiency of a staged combustion SSME. Think 410-415 sec at most, IMO, though PWR once projected 418 sec as a possible design goal.A regen RS-68 would cost more than standard RS-68 too. An alternative would be six or seven Vulcain 2 or J-2S type engines on the core. They would produce as much thrust as four SSMEs at better ISP than RS-68, but without requiring the staged combustion cycle. - Ed KyleWould six J2X engines be enough to ascend the core? I suppose their trhust at sea levelisn't that important with the 5-seg SRB's providing about 7M lbs of thrust. I can't find a SL thrust for J2X, but it's vacuum thrust is about 20% more than J2, so I'll assume it's SL thrust is 20% more than that of J2, so we'll say it's SL is around 140Klbs. RS-25 SL thrust is 415klbs. So 840klbs at lift off for six J2X's, vs. 1660Klbs for the four RS-25's at lift off. Would that be a problem?
At vacuum, it gets closer. six J2X putting out roughly 1750Klbs vs a bit over 2000Klbs for four RS-25's. That's probably the more important number, once the SRB's kick off. Is that enough to propell the rest of the stack to disposal orbit?If so, I kinda like the concept, since J2X will be developed whether there's a need for it or not. If three J2X engiens could be mounted in place of the two RS-25 pairs on SLS without too much headache.Interesting concept. Not sure if it really saves anything vs. just building more RS-25D's, or created RS-25E though, as SLS woudl be the only LV using either. But maybe it'd get the production rate up and I'd think they'd be cheaper than the labor intensive RS-25D's, and save the new development of RS-25E's. But if they aren't being shared with other LV's as RS-68 would, RS-25 might just be the best say to stick with.
Lobo, I do think you're focusing on the wrong area to really improve the SLS Bloc IB's costs. Rather than re-engining the core stage, which might cause all sorts of issues, I'd be looking much more at booster and especially upper stage upgrades. I know RS-25 engines are not cheap, but they're also a known quantity in that role, which is more than I can say for the J-2X. Who knows how much you'd have to re-design to handle replacing the Rs-25 engines on the core stage.
Interesting concept. Not sure if it really saves anything vs. just building more RS-25D's, or created RS-25E though, as SLS would be the only LV using either.
Our audit will examine NASA’s management of the next iteration of its Space Launch System heavy-lift rocket known as Block 1B. This complex and expensive endeavor seeks to use a significantly more powerful upper stage for transporting greater payloads to the Moon.
I know that this thread is a decade old, but I just noticed that the SLS Block 1B intended for the Artemis 4 mission will use the RS-25D for the core stage engines whereas the Block 1B rockets earmarked for the Artemis 5, 6, 7, and 8 missions will feature RS-25E core stage engines. How does the specific impulse of the RS-25E compare with that of the RS-25D? Does NASA intend to make a decision on which Artemis missions involving the Block 1B will carry cargo?
Teams at #NASAMichoud recently completed a major portion of a weld confidence article for the advanced upper stage of @NASA_SLS.SLS will evolve to its more powerful Block 1B configuration with the advanced upper stage beginning with #Artemis IV.MORE >>
Early Production Continues on Advanced Upper Stage for NASA Moon RocketLee MohonNOV 03, 2023Technicians at NASA’s Michoud Assembly Facility in New Orleans have completed a major portion of a weld confidence article for the advanced upper stage of NASA’s SLS (Space Launch System) rocket. The hardware was rotated to a horizontal position and moved to another part of the facility Oct. 24.The weld confidence article forms part of the liquid oxygen tank for the SLS rocket’s exploration upper stage and is the fifth of seven weld confidence articles engineers are manufacturing for the evolved SLS Block 1B configuration of the SLS rocket. Beginning with Artemis IV, SLS will evolve to its more powerful Block 1B configuration with the advanced upper stage that gives the rocket the capability to launch 40% more to the Moon along with Artemis astronauts inside NASA’s Orion spacecraft.Teams use weld confidence articles to verify welding procedures, interfaces between the tooling and hardware, and structural integrity of the welds. The dome of the liquid oxygen tank weld confidence article was first welded to its structural ring at NASA’s Marshall Space Flight Center in Huntsville, Alabama, using friction stir welding tooling. The hardware was transported to Michoud, where Michoud crews in the Liquid Oxygen Tank Assembly Center (LTAC) finished welding the hardware. Marshall and Michoud engineers simultaneously conducted testing and analysis on the hardware to validate welding parameters.In tandem, NASA and Boeing, the SLS lead contractor for the core stage and exploration upper stage, are producing structural test articles and flight hardware structures for the upper stage at Marshall and Michoud.NASA is working to land the first woman and first person of color on the Moon under Artemis. SLS is part of NASA’s backbone for deep space exploration, along with Orion and the Gateway in orbit around the Moon, and commercial human landing systems. SLS is the only rocket that can send Orion, astronauts, and supplies to the Moon in a single mission.For more on NASA SLS visit:https://www.nasa.gov/humans-in-space/space-launch-system/
Hi there Universal Stage Adapter! The USA is for the @NASA_SLS Block 1B, and will adapt @NASA_Orion to the Exploration Upper Stage, allowing for heavier payloads to be launched to the moon and beyond!
https://twitter.com/planetdeimos/status/1760697311288574006QuoteHi there Universal Stage Adapter! The USA is for the @NASA_SLS Block 1B, and will adapt @NASA_Orion to the Exploration Upper Stage, allowing for heavier payloads to be launched to the moon and beyond!
Mar 25, 2024 #Artemis #NASA #SLSA test version of the universal stage adapter for NASA’s SLS (Space Launch System) rocket has been on the move at NASA’s Marshall Space Flight Center in Huntsville, Alabama, and is now ready for testing. Following its delivery to Marshall by barge from nearby Decatur, teams moved and installed it onto the test stand in Building 4619 on March 12. Standing 32.4 feet tall and measuring 27.6 feet in diameter at its largest point, the universal stage adapter will connect NASA’s Orion spacecraft to the core stage and provide additional cargo space for the future Block 1B configuration of the mega-rocket, beginning with Artemis IV. Leidos is the lead contractor for the adapter, which is a first-time build for the SLS rocket. For more information about SLS, visit https://www.nasa.gov/sls
Technicians at @NASA_Marshall have been busy welding and working on the liquid oxygen forward dome for the Exploration Upper Stage (EUS) Structural Test Article (STA) in preparation for its move to NASA's Michoud Assembly Facility in New Orleans.Both the forward and aft domes will soon be shipped to Michoud, where they will be welded to the EUS liquid oxygen barrel section.
