Quote from: arachnitect on 02/26/2015 09:36 pmTheoretical LRBs out perform SRMs.Theoretical is nice, but it isn't sitting on a test stand in Utah right now. - Ed Kyle
Theoretical LRBs out perform SRMs.
Quote from: notsorandom on 02/25/2015 01:30 pmI have a feeling that the advanced boosters may get moved further into the future. There are a good number of steel cases left. I am not sure how many are around today but a few years ago there were enough to support 10 SLS flights.That is very old information. After careful inspection, they said the number passing inspection was enough for only 4 flights. This has been about 2 years ago that this was announced. The other 60 something casings were not in flyable condition.
I have a feeling that the advanced boosters may get moved further into the future. There are a good number of steel cases left. I am not sure how many are around today but a few years ago there were enough to support 10 SLS flights.
Quote from: notsorandom on 02/26/2015 05:08 pmQuote from: RanulfC on 02/26/2015 01:07 pmIt has always been about making sure that solids and only solids will be used for boosters. Period There are solid (pun intended) reasons for sticking with solid boosters with out having to ascribe any political reasons. Advanced solids represent the lowest cost upgrade to Block 1B SLS. For liquids a lot of modifications to the pad and ground support equipment would be required. There is no room on the MPL for any more connections so a new one would have to be built. The existing RP-1 lines date from the Saturns and would be of no use. New piping, and storage tanks would be needed.Oh I don't "need" to assign political reasons, but they are right there and up front about it being THE reason the payload requirements was chosen Hatch and the rest of the Utah delegation were quite proud of getting that exact number specified in the legislation because THAT number (they were assured by "experts") would require solid rocket boosters and nothing else would do. It's all on record. The whole LRB fiasco came along when it looked like Hatch might not be re-elected or might retire and a window of opportunity was seen but it was never a realistic option for the reasons you've given even if for no others. Personally I'm thinking we might be missing an opportunity for international cooperation by asking the Brits to resurrect their HTP program and building us some new boosters but that's probably only me Randy
Quote from: RanulfC on 02/26/2015 01:07 pmIt has always been about making sure that solids and only solids will be used for boosters. Period There are solid (pun intended) reasons for sticking with solid boosters with out having to ascribe any political reasons. Advanced solids represent the lowest cost upgrade to Block 1B SLS. For liquids a lot of modifications to the pad and ground support equipment would be required. There is no room on the MPL for any more connections so a new one would have to be built. The existing RP-1 lines date from the Saturns and would be of no use. New piping, and storage tanks would be needed.
It has always been about making sure that solids and only solids will be used for boosters. Period
Quote from: TomH on 02/25/2015 04:20 pmQuote from: notsorandom on 02/25/2015 01:30 pmI have a feeling that the advanced boosters may get moved further into the future. There are a good number of steel cases left. I am not sure how many are around today but a few years ago there were enough to support 10 SLS flights.That is very old information. After careful inspection, they said the number passing inspection was enough for only 4 flights. This has been about 2 years ago that this was announced. The other 60 something casings were not in flyable condition.I'd *really* like to see a reference or link for that. It's not my understanding of the situation. Cheers, Martin
From the article, it seems like there is actually no advanced booster competition. That that it is only between black knights and F1b, and that the outcome between these two is known.Am I getting it right?Or can there still be other participants?The obvious question is, for instant, can a certain company X offer their planned huge reusable rocket as a booster?
Quote from: edkyle99 on 02/27/2015 12:14 amQuote from: arachnitect on 02/26/2015 09:36 pmTheoretical LRBs out perform SRMs.Theoretical is nice, but it isn't sitting on a test stand in Utah right now. - Ed KyleNeither is an advanced solid.
I'd *really* like to see a reference or link for that. It's not my understanding of the situation.
Quote from: TomH on 02/27/2015 05:33 pmQuote from: edkyle99 on 02/27/2015 12:14 amQuote from: arachnitect on 02/26/2015 09:36 pmTheoretical LRBs out perform SRMs.Theoretical is nice, but it isn't sitting on a test stand in Utah right now. - Ed KyleNeither is an advanced solid.Sorry. Somebody said that we have SRBs because of the infamous "130t requirement" I was trying to point out that it's more like we have SRBs in spite of said requirement.We have SRBs because of the "shuttle derived" and schedule desires. But when it comes to the "130t requirement" they need either 1. a new core or 2. LRBs or 3. ignore 130t language.
Quote from: notsorandom on 02/26/2015 05:08 pmQuote from: RanulfC on 02/26/2015 01:07 pmIt has always been about making sure that solids and only solids will be used for boosters. Period RandyThere are solid (pun intended) reasons for sticking with solid boosters with out having to ascribe any political reasons. Advanced solids represent the lowest cost upgrade to Block 1B SLS. For liquids a lot of modifications to the pad and ground support equipment would be required. There is no room on the MPL for any more connections so a new one would have to be built. The existing RP-1 lines date from the Saturns and would be of no use. New piping, and storage tanks would be needed.IMHO the EUS was the right call. Advanced boosters in the Block 1A configuration could put 105 mt in LEO or more depending on the booster chosen. Beyond LEO is where SLS is needed and Block 1A isn't very much of an upgrade when the only upper stage is the ICPS. Block 1B without any advanced boosters can also do 105 mt to LEO but also around 40mt to TLI and similar trajectories. With the flat and limited funding SLS has it was either advanced boosters or EUS. The EUS enables more missions more quickly.
Quote from: RanulfC on 02/26/2015 01:07 pmIt has always been about making sure that solids and only solids will be used for boosters. Period RandyThere are solid (pun intended) reasons for sticking with solid boosters with out having to ascribe any political reasons. Advanced solids represent the lowest cost upgrade to Block 1B SLS. For liquids a lot of modifications to the pad and ground support equipment would be required. There is no room on the MPL for any more connections so a new one would have to be built. The existing RP-1 lines date from the Saturns and would be of no use. New piping, and storage tanks would be needed.
It has always been about making sure that solids and only solids will be used for boosters. Period Randy
More steel casing could be made. This was the plan for constellation which would have used 15 casings and two half casings for every lunar mission. Also recovery could be added back in. Its not like the limited number of casings is a brick wall, more like a very high speed bump. It may be the cost to upgrade to dark knights is low enough and the per unit savings is high enough that it just makes more sense to just go ahead and do them.
Quote from: notsorandom on 02/27/2015 07:41 pmMore steel casing could be made. This was the plan for constellation which would have used 15 casings and two half casings for every lunar mission. Also recovery could be added back in. Its not like the limited number of casings is a brick wall, more like a very high speed bump. It may be the cost to upgrade to dark knights is low enough and the per unit savings is high enough that it just makes more sense to just go ahead and do them.Supposedly they are cheaper, yet more profitable at the same time. I remember other threads where those with direct information said ATK moved quickly to shut down that kiln because there was more money to be had in the composites.
Regarding re-start of steel casing manufacture - see the document referenced in the following post (and comments in the post that follows):http://forum.nasaspaceflight.com/index.php?topic=27714.msg1212409#msg1212409(This was the situation as viewed in 2005.)
RAC-2 won all of the competitions vs. RAC-1 SDHLV...except the political competition.
In conducting its analysis and while maintaining a threshold safety requirement, the MSFC team performed an analytical hierarchy process and used weighted FOMs as follows:Affordability: 55 percentSchedule: 25 percentPerformance: 10 percentProgrammatic: 10 percentThe findings of the MSFC study showed that the 27.5-foot LOX/LH2/SSME HLV and 2Mlbf GG RP vehicles were highest rated across all of the FOMs. The 2.0 Mlbf RP engine vehicle scored better than the 1.25 Mlbf RP common engine because of its higher reliability (more engines would be required for 1.25 Mlbf). However, the LOX/LH2 RS-68 vehicle and the combined vehicles (LH core and RP strap-on boosters) did not fare well due to high potential costs and underrated performance.
The overarching goal of the SLS is to enable human exploration at the highest possible safety standards and the lowest life-cycle costs for beyond-LEO missions. Based on current information and analysis, the Reference Vehicle Design represents the lowest near-term costs, soonest available, and the least overall risk path to the development of the next, domestic heavy lift launch vehicle. Selecting this SLS architecture would mean that a new liquid engine in the near term would not need to be developed, thus shortening the time to first flight as well as likely minimizing the overall DDT&E cost of the SLS. However, the Reference Vehicle Design may not be affordable within expected budget levels. These issues are being considered in NASA’s ongoing trades and analyses, as outlined below.
What's your definition of "political"?
Quote from: MP99 on 02/27/2015 06:52 amI'd *really* like to see a reference or link for that. It's not my understanding of the situation.How about you? Would you consider your own self to be a reliable source?http://forum.nasaspaceflight.com/index.php?topic=30862.msg1202276#msg1202276http://forum.nasaspaceflight.com/index.php?topic=30862.msg1203715#msg1203715Don't feel bad though. I'm in my 60s now and forget all kinda stuff. Sometimes I think need an Alzheimer's test.
Quote from: Oli on 03/02/2015 07:39 pmWhat's your definition of "political"? A member of this site who was part of the RAC-2 told me directly RAC-2 won all technical and economic criteria vs. RAC-1. They even had a celebratory pizza party which the winning RAC team would get ( as a little friendly fun for the winner). Then they were told that RAC-1 would win because of political pressures which were inisting on shuttle derived/Ares V-ish. Of course, he could have been making all of that up...but...I'll opt to go with a direct source vs. the various thumb-on-the-scale official rationale...the same that got us Ares 1/5 vs. various other better options in ESAS and thus has already given us reason to be skeptical of their official rationales.