Quote from: ZachF on 11/07/2017 04:36 pmQuote from: oldAtlas_Eguy on 11/04/2017 04:48 pmProbable realistic launch plan schedule for SLS:EM-1 May 2020SM-1 July 2023EM-2 June 2024EM-3 June 2025SM-2 2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)EM-4 2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)Unless the engine build rate is increased there is no more launches in the 2020's.Assumptions:a) That ML-1 is modified to be a cargo only SLS-1B support.b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin. c) That EC is ready for launch by 6 months prior to its launch date in July 2023.d) That Europa Lander is ready for launch 6 months prior to its window in 2026.6 launches by 2028.... By then we would have spent >$40 billion on the SLS program.good god$6.7 billion per flight. That's $20 from every man, woman, and child in America to throw one of these up.A LEO flight of ~3 mT of logistics or crew costs every man, woman and child in the U.S. about $1 on average. SLS is almost an order of magnitude bigger(70-130 mT vs 7 mt - 22 mT LEO).
Quote from: oldAtlas_Eguy on 11/04/2017 04:48 pmProbable realistic launch plan schedule for SLS:EM-1 May 2020SM-1 July 2023EM-2 June 2024EM-3 June 2025SM-2 2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)EM-4 2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)Unless the engine build rate is increased there is no more launches in the 2020's.Assumptions:a) That ML-1 is modified to be a cargo only SLS-1B support.b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin. c) That EC is ready for launch by 6 months prior to its launch date in July 2023.d) That Europa Lander is ready for launch 6 months prior to its window in 2026.6 launches by 2028.... By then we would have spent >$40 billion on the SLS program.good god$6.7 billion per flight. That's $20 from every man, woman, and child in America to throw one of these up.
Probable realistic launch plan schedule for SLS:EM-1 May 2020SM-1 July 2023EM-2 June 2024EM-3 June 2025SM-2 2026 (whenever the launch window in this year occurs) (plus this is the first flight of the RS-25Es, ASAP will want a unmanned flight of these engines first before a manned one) (this engine set will not be available to support a flight until this time anyway so it could not be done any earlier)EM-4 2028 (it takes 2 years to deliver 4 RS-25Es on the current contract) (It will require a bigger budget and a new contract to increase the build rate to deliver 4 engines per year instead of the current contract delivery rate of 2 engines per year)Unless the engine build rate is increased there is no more launches in the 2020's.Assumptions:a) That ML-1 is modified to be a cargo only SLS-1B support.b) That an ML-2 is constructed with lessons learned to make a crew version of the ML with a budget funded at a level allowing it to be constructed in 5 years starting Oct 2018. This gets a ML available to support the June 2024 EM-2 date at better than 6 months prior to launch date plus a few months of margin. c) That EC is ready for launch by 6 months prior to its launch date in July 2023.d) That Europa Lander is ready for launch 6 months prior to its window in 2026.
Also, use of EUS and the matching-size PLF would allow a more massive (larger propellant tanks = more propellant = longer mission/greater mission flexibility at mission target), taller, and wider spacecraft, to accommodate the radiation shielding and multiple-instrument payload, would it not?
There seems to be an assumption peeking out behind most of the negative posts here -- that the SLS will almost inevitably fail on its first flight.
Quote from: the_other_Doug on 11/07/2017 03:45 pmThere seems to be an assumption peeking out behind most of the negative posts here -- that the SLS will almost inevitably fail on its first flight.I'm a critic of SLS, but I don't expect it or EUS to fail on first, but surely it's beyond dispute that launching the very expensive EC on SLS is much riskier than launching it on the very well proven Atlas V.
They are really going to redesign the entire mobile launchers because it will end up with a safety factor of 3.75 instead of 4.0 for the block 1B configuration? Seriously? And that's going to take 3 years?
Plus, it's not like this structure is going to see a high number of duty cycles where additional structural margin is required to actually build a safe structure with launches taking place off of it once every two years at best.
And every launch vehicle built in the US has been designed to 1.25 and not 1.4
Quote from: zubenelgenubi on 11/05/2017 09:11 pmAlso, use of EUS and the matching-size PLF would allow a more massive (larger propellant tanks = more propellant = longer mission/greater mission flexibility at mission target), taller, and wider spacecraft, to accommodate the radiation shielding and multiple-instrument payload, would it not?(One of our resident experts would be able to express this better than me, I think.)The spacecraft size is already fixed. It is dual compatible with SLS and other existing launch vehicles.
Also, use of EUS and the matching-size PLF would allow a more massive (larger propellant tanks = more propellant = longer mission/greater mission flexibility at mission target), taller, and wider spacecraft, to accommodate the radiation shielding and multiple-instrument payload, would it not?(One of our resident experts would be able to express this better than me, I think.)
Quote from: Proponent on 11/07/2017 09:58 pmI'm a critic of SLS, but I don't expect it or EUS to fail on first, but surely it's beyond dispute that launching the very expensive EC on SLS is much riskier than launching it on the very well proven Atlas V.Were you this adamant that the billion dollar New Horizons probe not use the first Atlas 551(7th Atlas V overall) and instead use a smaller flight tested vehicle even if it took longer? And that was a nuclear payload.
I'm a critic of SLS, but I don't expect it or EUS to fail on first, but surely it's beyond dispute that launching the very expensive EC on SLS is much riskier than launching it on the very well proven Atlas V.
Quote from: ncb1397 on 11/07/2017 10:46 pmQuote from: Proponent on 11/07/2017 09:58 pmI'm a critic of SLS, but I don't expect it or EUS to fail on first, but surely it's beyond dispute that launching the very expensive EC on SLS is much riskier than launching it on the very well proven Atlas V.Were you this adamant that the billion dollar New Horizons probe not use the first Atlas 551(7th Atlas V overall) and instead use a smaller flight tested vehicle even if it took longer? And that was a nuclear payload.By the time an Atlas V 551 launched New Horizions, the Atlas V core had already flown 6 times, as you point out, the SRBs had been flown 7 times, and the Centaur had flown many times. Flying 5 with 5 SRBs when at most 3 had flown before was a risk factor, but a small one compared to flying on the second ever SLS and first ever EUS.
Quote from: Proponent on 11/10/2017 01:16 amBy the time an Atlas V 551 launched New Horizions, the Atlas V core had already flown 6 times, as you point out, the SRBs had been flown 7 times, and the Centaur had flown many times. Flying 5 with 5 SRBs when at most 3 had flown before was a risk factor, but a small one compared to flying on the second ever SLS and first ever EUS.By the same logic, the RS-25 & solid boosters will have flown on 136 missions (135 STS, 1 SLS), and the core stage will have been flight proven one (1) SLS mission. The RL-10 engines on the EUS have been flown since 1963.
By the time an Atlas V 551 launched New Horizions, the Atlas V core had already flown 6 times, as you point out, the SRBs had been flown 7 times, and the Centaur had flown many times. Flying 5 with 5 SRBs when at most 3 had flown before was a risk factor, but a small one compared to flying on the second ever SLS and first ever EUS.
I buy the logic for the RS-25s, but they are not the same engines that have flown previously. Designs and details are different (and I think even from the previously flown engines to be used on the SLS).The SRBs are a new 5 segment design, different chemical make up (as I recall), and a different nozzle, with only 2 test firings, not under flight conditions plus 2 for the first flight of SLS.The RL-10s are not the same as flown in 1963, but do have more recent flight heritage.
Quote from: mike robel on 11/10/2017 02:32 pmI buy the logic for the RS-25s, but they are not the same engines that have flown previously. Designs and details are different (and I think even from the previously flown engines to be used on the SLS).The SRBs are a new 5 segment design, different chemical make up (as I recall), and a different nozzle, with only 2 test firings, not under flight conditions plus 2 for the first flight of SLS.The RL-10s are not the same as flown in 1963, but do have more recent flight heritage.Just a correction, 5-segment SRBS have been test fired 5 times, 3 development test fires (in 2009, 2010, and 2011) and 2 qualification test fires (in 2015 and 2016).
1. If you see the various presentations that Papalardo has done on Europa Clipper, Atlas V is both weight and volume limited. It is not just that it will take a series of flybys to get to Jupiter and Europa, Clipper is running into the maximum weight limit of Atlas V and into the volume limit of its shroud.
Thanks -- can you give me a pointer to the relevant presentations?
Quote from: Proponent on 11/12/2017 08:52 pmThanks -- can you give me a pointer to the relevant presentations?Check out the link below. I don't know if all the trajectory options are still valid with the current masshttps://sites.nationalacademies.org/cs/groups/ssbsite/documents/webpage/ssb_172023.pdf