..... Quote from: TomH on 03/22/2013 10:10 pmThe core should use the sustainers all the way to disposal orbit. If only assembly components are atop the core, only circularization is required. If the hardware atop the core will depart LEO for deep space, the mass and thrust of J-2X are unnecessary and its lower ISP a disadvantage. With little gravity loss to counter, RL-10 is the right choice.You don't necessarily have to use a J-2X, which has inferior Vac Isp compared to the RS-25. As I'm sure HappyMartian will remind you, the MB-60 might be an even better choice for that job. Regardless, won't the SLS Bloc IB have such a large upper stage that it'll be straining this possibility of the core doing all but the circularization burn? Given the SLS Bloc I will only put around 95 mt into LEO, I don't think the Bloc IB will be able to not have its upper stage do the latter part of the ascent burn. If that's the case, then we're arguing over a matter of degrees, not some fundamental difference.
The core should use the sustainers all the way to disposal orbit. If only assembly components are atop the core, only circularization is required. If the hardware atop the core will depart LEO for deep space, the mass and thrust of J-2X are unnecessary and its lower ISP a disadvantage. With little gravity loss to counter, RL-10 is the right choice.
Someone suggested that we put the current configuration in the first entry, so here goes:AJAX is a means of achieving the goals of the Congressionally mandated Space Launch System while reducing overhead costs by sharing resources with other United States launch systems. ...
Quote from: TomH on 03/22/2013 10:10 pmSLS [...] at least for Mars, must use LEOR to assemble components.What rules out Lagrange point assembly?QuoteWhat would you do with three to seven half fueled upper stages while assembling Mars components in LEO?That's not a problem ... for Lagrange point assembly!
SLS [...] at least for Mars, must use LEOR to assemble components.
What would you do with three to seven half fueled upper stages while assembling Mars components in LEO?
once a vehicle reaches orbital V, any ΔV beyond that can be done at low thrust very high ISP, i.e. SEP tug.
Quote from: TomH on 03/23/2013 04:52 amonce a vehicle reaches orbital V, any ΔV beyond that can be done at low thrust very high ISP, i.e. SEP tug.Perhaps that would be true if a tug were available. Have you seen its development listed on the SLS Top Level Milestone charts? They extend out through 2025....
We won't be going to Mars within that time frame. In the meantime, building the rocket such that the core can reach disposal orbit gives maximum versatility to SLS. You can put a chemical EDS atop it for Luna or an EML point. You can assemble components for an asteroid, Phobos rendezvous, or Mars orbit mission and use a chemical EDS. Later, when we want to land on Mars, several assemblies can be put together and flown by SEP tug in sequence. Building the rocket so that it can accommodate all these profiles without the rocket itself needing modifications along the way is the wisest path forward. Payloads change, but the rocket doesn't. Build it once in a manner that will accommodate this full spectrum of missions, then leave the design alone.
Quote from: TomH on 03/23/2013 02:27 pmWe won't be going to Mars within that time frame. In the meantime, building the rocket such that the core can reach disposal orbit gives maximum versatility to SLS. You can put a chemical EDS atop it for Luna or an EML point. You can assemble components for an asteroid, Phobos rendezvous, or Mars orbit mission and use a chemical EDS. Later, when we want to land on Mars, several assemblies can be put together and flown by SEP tug in sequence. Building the rocket so that it can accommodate all these profiles without the rocket itself needing modifications along the way is the wisest path forward. Payloads change, but the rocket doesn't. Build it once in a manner that will accommodate this full spectrum of missions, then leave the design alone.I agree with everything you wrote there ... and I believe Boeing does too. They are designing a core that will only be used in a four RS-25 configuration. Configured with 5-seg boosters, a small upper stage (i.e. ICPS) and payload, that core reaches an almost-orbital disposal trajectory and the ICPS sends about 24 tonnes through TLI.That exact same core, assisted at lift-off by the exact same boosters, but augmented by a larger upper stage, could do much better. With a ~200 tonne upper stage it could put ~45 tonnes through TLI. That's a capability that could be used to great benefit for decades.When the time comes for a Mars surface mission, one option would be to use the exact same core, maybe with advanced boosters but no upper stage, for an LEOR assembly architecture. But we don't know that will be the architecture chosen. (Just for example, a lunar-derived abundant-chemical architecture with EML assembly might be chosen instead.)The ~200 tonne upper stage enables a truly flexible path. Advanced boosters ... don't.
For Block 1B can the US be 5.5m?If so then if they choose the LRB's then they could first start them out as the single stick with a (4) RL-10 US ( US to be used then as the SLS US ). Later change the engine mount for a J-2X for greater mass to LEO for the single stick, same tanks for the US.
losing one of four RL-10A-4-2 engines would see the remainder exceed their maximum burn time.
Quote from: RocketmanUS on 03/24/2013 02:54 amFor Block 1B can the US be 5.5m?If so then if they choose the LRB's then they could first start them out as the single stick with a (4) RL-10 US ( US to be used then as the SLS US ). Later change the engine mount for a J-2X for greater mass to LEO for the single stick, same tanks for the US.Btw, I did some checking as to how you could max your LEO figures on a 5.5 meter stage. Although I profess it would be ridiculously overpowered, you could stuff four J-2S engines, complete with gimbals, into a 5.5 meter stage. Heck, you might even be able to add a nozzle extension on each one to improve their Isp modestly. Those engines are only 2.01 meters in diameter after all. I personally would only use a pair of them to keep things less ridiculous, but they'd give you a huge helping of power out of what is otherwise a modest diameter HLV stage. A pair or trio of J-2S engines on a super-sized version of the 8.4 m CPS with large nozzle extensions would likely do even better. It's too bad the J-2S never saw service, because it appears just as well suited, with help from a nozzle extension, as the J-2X.
For Block 1B can the US be 5.5m?If so then if they choose the LRB's then they could first start them out as the single stick with a (4) RL-10 US ( US to be used then as the SLS US ). Later change the engine mount for a J-2X for greater mass to LEO for the single stick, same tanks for the US.So we could test the boosters out before even launching a SLS.Would it be possible to use one of the shuttle hangers to process the 1st and 2nd stages of the single core?So develop the LRB's and US.Test it out as the single stick.Then put the boosters on the SLS core for it's first launch.They say they need seven years to develop the advanced boosters.That brings us to around 2020. If they delay the first two test flights till 2020 as there does not seem to be any missions for the SLS yet, then they could skip using the 5 segs SRB's that they don't plan on using for the SLS BLEO future missions.Only an idea.Edit:The single stick could test Orion in LEO with a test crew before sending it on later missions BLEO.
I’d probably suggest going with building the Block 1B upper stage now, and launching that 8.4m upper stage on a single booster core (maybe with a partial prop load) and making that your common upper stage. Especially if there’s no sharing with any other LV other than SLS and the SLS LRB.But, better than any of that I think, is back to my concept of the FH booster. Mount two FH’s as SLS boosters. No need to develop a new upper stage other than the Block 1B stage then. It can launch and test Orion before putting a crew on the SLS stack.
Quote from: Lobo on 03/25/2013 04:47 pmI’d probably suggest going with building the Block 1B upper stage now, and launching that 8.4m upper stage on a single booster core (maybe with a partial prop load) and making that your common upper stage. Especially if there’s no sharing with any other LV other than SLS and the SLS LRB.But, better than any of that I think, is back to my concept of the FH booster. Mount two FH’s as SLS boosters. No need to develop a new upper stage other than the Block 1B stage then. It can launch and test Orion before putting a crew on the SLS stack. Lobo, the engine count we're talking about with two Falcon Heavies mounted onto the side of the SLS is off the charts. To my knowledge, the highest engine count for simultaneous firing was 30 on the N-1, and that failed spectacularly. I've seen Mythbusters struggle with simultaneous ignition with just a few dozen fireworks for goodness sakes. Now imagine trying to fire up some 54 Merlin 1D engines at the same time alongside the four RS-25 engines on the central core. That's 58 rocket engines going at the same time. It sounds like an engineering nightmare. Ed Kyle and Jim are skeptical enough of the Falcon Heavy's design as it is. Now imagine their reactions if you were their boss and said this was the way forward.
If we're talking a common 8.4 m upper stage for the booster LV & SLS, the RL-10 is not going to be the most ideal. Even supposing the LRBs had three AJ-1-E6 engines or a pair of RD-170 engines, the booster LV is going to be staging much earlier than the SLS core. If however we're talking about a quartet of RL-60 engines or NGEs, I'd be more enthusiastic about this common upper stage.
Well obviously if the 8.4m upper stage were to be used as a common upper stage, that would be incorporated into it’s design. Which would include RL-60’s, or NGE’s or whatever, as necessary. It might even mean that a single J2X is used on both so it could do double duty, even if it isn’t the most ideal for SLS. I –think- that’s why the S-IVB had the J2, so that it could do double duty on the Saturn 1B as well. I don’t think a J2 was necessary for it as the Saturn V’s 3rd stage. But RL-10’s wouldn’t work on the S-IVB on the Saturn 1B.
Well obviously if the 8.4m upper stage were to be used as a common upper stage, that would be incorporated into it’s design. Which would include RL-60’s, or NGE’s or whatever, as necessary. It might even mean that a single J2X is used on both so it could do double duty, even if it isn’t the most ideal for SLS. I –think- that’s why the S-IVB had the J2, so that it could do double duty on the Saturn 1B as well. I don’t think a J2 was necessary for it as the Saturn V’s 3rd stage. But RL-10’s wouldn’t work on the S-IVB on the Saturn 1B. Maybe I’m in error on that though. RL-60 or MB-60 would probably be the best engine for a double duty 8.4m upper stage though. As good of ISP as the RL-10, and about the same size, but over twice the thrust. And that for only double the mass…which is only 0.5mt. When used as the SLS upper stage, it would only need maybe two RL-60’s. And then it could mount four when used as a booster upper stage. It would also mean the booster would launched as a single stick could use the same PLF’s as SLS, as they’d mate with the same upper stage for both LV’s. And Maybe with the development of an MB-60 or RL-60, ULA might consider going to it for the EELV’s for cost sharing.
"While the SLS Block 2 – with advanced Solid Rocket Boosters – is estimated to provide a capability of 130mt to orbit, Dynetics claim that by using the vehicle assumptions for the fully evolved SLS, their proposed booster delivers 150mt, 'providing a 20mt (15 percent) margin, even with a conservative, affordability-focused booster.'"From: Dynetics and PWR aiming to liquidize SLS booster competition with F-1 powerBy Chris Bergin November 9, 2012 At: http://www.nasaspaceflight.com/2012/11/dynetics-pwr-liquidize-sls-booster-competition-f-1-power/If you add the margin of "20mt" to the "150mt" "to orbit" you get an SLS with a 170 mt to orbit. Let's see, that would be about 170,000 kilograms, and that would be about 374,785 pounds or around 187 tons into orbit.
The evolved SLS with F-1 powered LRBs could put about 170,000 kgs to LEO and is obviously a powerful Nova class launcher. As a Nova launcher it might even have more capability to LEO than the "Nova N-M1".The name Nova sounds good. A Nova launcher could be around for many decades. See also: Nova (rocket) WikipediaAt: http://en.wikipedia.org/wiki/Nova_%28rocket%29