As for RS-25E on SLS versus RS-68, remember a few things: 1. Ares V with RS-68 necessitated an increase in core diameter, dramatically increasing the overall costs of the core. 2. Eventually it required a sixth engine on the core due to the performance of the rS-68.3. Ultimately Constrllation was working a switch back to the SSME versus RS-68
As for RS-25E on SLS versus RS-68, remember a few things: 1. Ares V with RS-68 necessitated an increase in core diameter, dramatically increasing the overall costs of the core. 2. Eventually it required a sixth engine on the core due to the performance of the rS-68.3. Ultimately Constrllation was working a switch back to the SSME versus RS-68RS-25E always has a backup configuration in the D model, which in large block buys will decrease per unit costs. Any changes for E will have little performance gains but will focus on lowering costs. Any changes to the RS-68 to work for SLS in the thermal environment of the RSMV will dramatically increase its cost, so better for ULA/USAF ect to leave it be. Besides, j-2x has used RS-68 components, and it has been stated the -25E will as well.
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.
simply using three SLS core stages in a Delta-IV heavy configuration.
Quote from: hydra9 on 03/29/2012 10:36 pmIronically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.Not true
Quote from: hydra9 on 03/29/2012 10:36 pm simply using three SLS core stages in a Delta-IV heavy configuration. That is nonsense. The forward SRB attach fittings and the lack of aft support structure means the SLS cores can not be used in that fashion without a complete redesign.
The first SLS core stage is some five years away from its first launch configuration which still gives NASA time to develop a core stage that can be flexibly used with or wthout SRBs or side-mounted rockets
Quote from: Jim on 03/30/2012 02:18 amQuote from: hydra9 on 03/29/2012 10:36 pmIronically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized.Not truePlease elaborate!
Quote from: edkyle99 on 02/26/2012 05:57 pmQuote from: mikegi on 02/26/2012 05:47 pmQuick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.You would need about 1.5 to 1.6 RS-25 engines to replace each RS-68 - which from a practical standpoint of course means that you would need two RS-25 engines for each Delta IV core. The cost comparison would have to take that into account, along with the significant cost of re-engineering Delta IV to handle the new propulsion. - Ed Kyle Yea, this really begs a few questions.Within a couple years, assuming F9, FH, and Antaries get flying ok, does ULA need two redundant launchers in A5 and D4? Those two LV’s were born of the DoD wanting backup LV’s so they wouldn’t be hosed if one was grounded for some reason like they were with STS after Challenger. Two companies, two LV’s. But now that they are merged, and there’s other similar class LV’s about to come on line, I’m not sure the need for ULA to maintain two separate LV’s that do essentially the same thing. I think the advantage of D4, is if the launch rate was high enough, it’s costs could be very cheap. But ULA will never get that splitting their work between two launchers. Especially if SpaceX and Orbital cut into their DoD work at all.A5 has better growth potential into larger capacity LV’s visa vi A5P2. So what does ULA do going forward? Eliminate one or the other? If so, which one? Personally, I don’t think having hydrolox as a first stage is a good way to go, so I’d probably look at eliminating D4 all together, and using that tooling to make A5P2 to replace D4H. So ULA has two CCB’s, but common engines, probably common avionics, and if they developed ACES, common upper stages. LC-37B could be modified, fairly easily I would think, to take a 5m kerolox core instead of the 5m hydrolox D4 core. And it should even be able to handle a future A5P2-Heavy, which would have the same footprint as the current D4H (although much greater thrust). LC-41 would continue to launch A5’s as normal for the normal EELV-class payloads.Centralize around the A5 platform, fold up the D4 platform, and try to get those flight rates up and costs down. Which would mean eliminating the need for the RS68 completely. Going the other way and eliminating the A5, then you could look at centralizing around the single 5m hydrolox core, with RS25E engines. Each core would need two RS25’s throttling, so the ultimate price per core would go up, but perhaps the price of the RS25E’s could come down enough with the shared SLS and D4 volume to be similar to current RS68 prices. The economics of scale at work, especially if they can trim down the RS25E enough since it doesn’t need to be reused anymore. A D4H could have two RS25E’s on each booster CCB, and then one on the central core. Your total thrust should be about the same as three RS68’s, but the core should be able to put the payload directly into LEO without the need for a 2nd stage burn. Or at least just a brief one as will be the case with SLS 1 and 1A. That should gain you some BLEO performance on the D4H. (But I’m not expert, so this is just gut feeling).However, I think Downix or someone said at one point that even if PWR is making both the RS68 and RS25E, though they are not the same engine, they do share a lot of the same infrastructure, so increasing use of one brings the cost of both down. The same facilities, personnel, and equipment and such would be used for both, as well as J2X. Even though that’d be 3 engines, the economies of scale are shared. Again, I just remember that being said, no sure if it’s true. But if it is, Then ULA could just stick with RS68’s on their D4 LV’s (and save redesign costs), and those prices will come down due to all ULA launches being on D4, so twice as many RS68’s being produced and not split between two LV’s, and with the RS25E’s being produced for SLS. As well as J2X eventually…maybe…
Quote from: mikegi on 02/26/2012 05:47 pmQuick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.You would need about 1.5 to 1.6 RS-25 engines to replace each RS-68 - which from a practical standpoint of course means that you would need two RS-25 engines for each Delta IV core. The cost comparison would have to take that into account, along with the significant cost of re-engineering Delta IV to handle the new propulsion. - Ed Kyle
Quick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.
Quote from: Lobo on 02/28/2012 05:06 pmQuote from: edkyle99 on 02/26/2012 05:57 pmQuote from: mikegi on 02/26/2012 05:47 pmQuick, and probably stupid, question from a non-rocket scientist: if the RS-25E actually approaches the cost of the RS-68, could it replace the RS-68 as our all-purpose H2 engine? It seems like it would be a good idea to, as the saying goes, put all our wood behind one arrow.You would need about 1.5 to 1.6 RS-25 engines to replace each RS-68 - which from a practical standpoint of course means that you would need two RS-25 engines for each Delta IV core. The cost comparison would have to take that into account, along with the significant cost of re-engineering Delta IV to handle the new propulsion. - Ed Kyle Yea, this really begs a few questions.Within a couple years, assuming F9, FH, and Antaries get flying ok, does ULA need two redundant launchers in A5 and D4? Those two LV’s were born of the DoD wanting backup LV’s so they wouldn’t be hosed if one was grounded for some reason like they were with STS after Challenger. Two companies, two LV’s. But now that they are merged, and there’s other similar class LV’s about to come on line, I’m not sure the need for ULA to maintain two separate LV’s that do essentially the same thing. I think the advantage of D4, is if the launch rate was high enough, it’s costs could be very cheap. But ULA will never get that splitting their work between two launchers. Especially if SpaceX and Orbital cut into their DoD work at all.A5 has better growth potential into larger capacity LV’s visa vi A5P2. So what does ULA do going forward? Eliminate one or the other? If so, which one? Personally, I don’t think having hydrolox as a first stage is a good way to go, so I’d probably look at eliminating D4 all together, and using that tooling to make A5P2 to replace D4H. So ULA has two CCB’s, but common engines, probably common avionics, and if they developed ACES, common upper stages. LC-37B could be modified, fairly easily I would think, to take a 5m kerolox core instead of the 5m hydrolox D4 core. And it should even be able to handle a future A5P2-Heavy, which would have the same footprint as the current D4H (although much greater thrust). LC-41 would continue to launch A5’s as normal for the normal EELV-class payloads.Centralize around the A5 platform, fold up the D4 platform, and try to get those flight rates up and costs down. Which would mean eliminating the need for the RS68 completely. Going the other way and eliminating the A5, then you could look at centralizing around the single 5m hydrolox core, with RS25E engines. Each core would need two RS25’s throttling, so the ultimate price per core would go up, but perhaps the price of the RS25E’s could come down enough with the shared SLS and D4 volume to be similar to current RS68 prices. The economics of scale at work, especially if they can trim down the RS25E enough since it doesn’t need to be reused anymore. A D4H could have two RS25E’s on each booster CCB, and then one on the central core. Your total thrust should be about the same as three RS68’s, but the core should be able to put the payload directly into LEO without the need for a 2nd stage burn. Or at least just a brief one as will be the case with SLS 1 and 1A. That should gain you some BLEO performance on the D4H. (But I’m not expert, so this is just gut feeling).However, I think Downix or someone said at one point that even if PWR is making both the RS68 and RS25E, though they are not the same engine, they do share a lot of the same infrastructure, so increasing use of one brings the cost of both down. The same facilities, personnel, and equipment and such would be used for both, as well as J2X. Even though that’d be 3 engines, the economies of scale are shared. Again, I just remember that being said, no sure if it’s true. But if it is, Then ULA could just stick with RS68’s on their D4 LV’s (and save redesign costs), and those prices will come down due to all ULA launches being on D4, so twice as many RS68’s being produced and not split between two LV’s, and with the RS25E’s being produced for SLS. As well as J2X eventually…maybe…So for SLS and RS25es - SRMs can meet the metric tonne requirements - incorporating solids drastically increase crew LAS mass (not common to multiple LVs ) - new liquid boosters still *requires* RS25s (regen)-base heating - 8-10 launches per year provides 1000 mT significantly exceeds need - economics of 4-6 launches per year significantly favors smaller LVs - RS-68R not worth the dollars (?) not common with other configs - P&W are modernizing plant to reduce costs - still loses economically to a smaller LV to service ISS - Studies indicate US should launch crew at least two vehicles - US and world has excess launch capacity - J2X - has no commonality with any other element - the whole exercise is comes across as trying to fit square pegs... - SLS its just not viable economicallySo since this is the RS-25 E thread, your discussion above on the go-forward plan without SLS ( Atlas Delta Falcon Russia etc) is spot on and should be discussed on an existing thread or new one. Suggestions?But to continue the discuss with SLS is counterproductive.Actually, the time spent on SLS hardware may actually be providing the advantage of other COTS LVs vs Human Rating Atlas and Delta
NASA anticipates a re-start of theproduction line for the RS-25 engine that it plans to use to power theBlock IA/B and Block II vehicles [...] but it has not yet finalized acquisition plans tomanufacture them. According to agency officials, re-starting theproduction line would entail at least 3 years, whereas development ofa new engine would require a minimum of 8 years.
QuoteNASA anticipates a re-start of theproduction line for the RS-25 engine that it plans to use to power theBlock IA/B and Block II vehicles [...] but it has not yet finalized acquisition plans tomanufacture them. According to agency officials, re-starting theproduction line would entail at least 3 years, whereas development ofa new engine would require a minimum of 8 years.http://www.gao.gov/assets/670/663071.pdfIs GAO talking about RS-25E or something else entirely when they say, "development of a new engine?"
A "minimum of 8 years" for RS-25E? Crazy.
Ironically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized. And as previous posters have noted, this would be an extremely heavy vehicle to transport to the launching pad. But there is a possible scenario that could actually reintroduce the current RS-68 engines back into the mix. The current SSME are limited to only 15 engines and it looks like the RS-25E won't be ready for production until at least 2021. If NASA decided to limit the use of the SSME only to man-rated test and manned flights, only 3 engines would be required with SRBs with the possibility of up to 5 missions (one or two unmanned test missions and three or four manned missions). But that would mean that there would be no engines available to test cargo missions until 2021. However, RS-68 engines could be utilized for unmanned heavy lift cargo missions without SRBs by simply using three SLS core stages in a Delta-IV heavy configuration. Boeing originally proposed such a vehicle, utilizing 8 meter in diameter core stages, each propelled by 4 RS-68 engines. With an upper stage, such a vehicle was argued to able to lift more than 146 tonnes into orbit. The SLS core stage will have an 8.4 meter diameter. So with an upper stage, such a vehicle should exceed the lifting capability of the Delta Super Heavy concept. This would mean that no new side-mounted boosters would have to be developed and no new engines. It could also mean that SLS super heavy cargo boosters could be tested as early as 2017 instead of waiting until perhaps the mid 2020s for a new solid or liquid booster to be ready to be utilized. Marcel F. Williams
Keep in mind , A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.
Quote from: bilbo on 05/12/2014 11:15 pmKeep in mind , A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.... yep, and if only someone from the other party was president, we would all get ponies.
Quote from: hydra9 on 03/29/2012 10:36 pmIronically, the 5-segment SRBs are still not enough to achieve the mandated ultimate goal of being able to lift at least 130 metric tons into orbit-- unless four of the heavy solid rocket boosters are utilized. And as previous posters have noted, this would be an extremely heavy vehicle to transport to the launching pad. But there is a possible scenario that could actually reintroduce the current RS-68 engines back into the mix. The current SSME are limited to only 15 engines and it looks like the RS-25E won't be ready for production until at least 2021. If NASA decided to limit the use of the SSME only to man-rated test and manned flights, only 3 engines would be required with SRBs with the possibility of up to 5 missions (one or two unmanned test missions and three or four manned missions). But that would mean that there would be no engines available to test cargo missions until 2021. However, RS-68 engines could be utilized for unmanned heavy lift cargo missions without SRBs by simply using three SLS core stages in a Delta-IV heavy configuration. Boeing originally proposed such a vehicle, utilizing 8 meter in diameter core stages, each propelled by 4 RS-68 engines. With an upper stage, such a vehicle was argued to able to lift more than 146 tonnes into orbit. The SLS core stage will have an 8.4 meter diameter. So with an upper stage, such a vehicle should exceed the lifting capability of the Delta Super Heavy concept. This would mean that no new side-mounted boosters would have to be developed and no new engines. It could also mean that SLS super heavy cargo boosters could be tested as early as 2017 instead of waiting until perhaps the mid 2020s for a new solid or liquid booster to be ready to be utilized. Marcel F. WilliamsKeep in mind , A new President elect is coming in 2016. Advanced boosters could be ready by 2020-2022, if they made insane progress.