Quote from: Prettz on 03/14/2016 07:59 pmWhat was so wrong with using the F-1B?Congress has determined that the AR-1 shall exist, ye, verily.That's not to rule out a future such decree on behalf of the F-1B, which I think would have given me more joy, as arbitrary declarations go. Perhaps when SpaceX and/or Blue get around to fielding a really great big rocket, Congress will hold hearings on why the USA doesn't have one yet.
What was so wrong with using the F-1B?
For Block IB, its just under 1g at SRB separation. Actual acceleration is 9.5 m/sē.
Quote from: daveklingler on 03/15/2016 05:15 amQuote from: Prettz on 03/14/2016 07:59 pmWhat was so wrong with using the F-1B?Congress has determined that the AR-1 shall exist, ye, verily.That's not to rule out a future such decree on behalf of the F-1B, which I think would have given me more joy, as arbitrary declarations go. Perhaps when SpaceX and/or Blue get around to fielding a really great big rocket, Congress will hold hearings on why the USA doesn't have one yet.USA will have two (or three, if VulcanHeavy is built, too) -- Congress will have to decide whether to follow their own law, or change it to keep their pet project(s) relevant.To the maximum extent practicable, the Federal Government shall plan missions to accommodate the space transportation services capabilities of United States commercial providers. US law http://goo.gl/YZYNt0-- Robotbeat's signature lineNOTE: The USG is not the USA.
Do not forget SLS is a political beast. Congress can change their minds as to what they want. As in a 200+mt launcher for Mars not just a 100mt maybe a 130mt launcher. Such as liquid boosters, 5 engine RS-68A core, J-2X second stage and a RL-10 EDS. Plus use something else (commercial LV) to get Orion into LEO where it docks with the rest of the Mars stack. Constellation resurrected.
Steven, are you set up to easily simulate an AR-1-based SLS? I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.
Quote from: daveklingler on 03/15/2016 04:44 pmSteven, are you set up to easily simulate an AR-1-based SLS? I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.Its relatively easy, but each simulation takes me half a day to perform. I use my own custom coded Pascal software. Its not a spreadsheet. I have already simulated liquid boosters with three AJ1E6 dual nozzle engines. I could use that to simulate six AR-1 engines.
Quote from: Steven Pietrobon on 03/16/2016 03:07 amQuote from: daveklingler on 03/15/2016 04:44 pmSteven, are you set up to easily simulate an AR-1-based SLS? I'm assuming you've long since set up a spreadsheet, since you've done several simulations at this point.Its relatively easy, but each simulation takes me half a day to perform. I use my own custom coded Pascal software. Its not a spreadsheet. I have already simulated liquid boosters with three AJ1E6 dual nozzle engines. I could use that to simulate six AR-1 engines.I could be mistaken, but I think he means AR-1 on the core, not AR-1 boosters.
I did mean the core, but I recognize that the boosters have a slightly better chance of seeing AR-1s than the core does. It sounds like you're saying that the code you already wrote is applicable to either one?
I just found your 2013 SLS/F1B/AJ1E6 paper and reread it. It seems like you might be able to take AJR at their word and basically plug in RD-180s, since they have said emphatically that they are doing their best to duplicate the RD-180 in every significant way. I don't think they can come in much less or much above the RD-180's thrust level, nor can the Isp vary much, which means identical chamber size and pressure, bell dimensions, etc. Somewhere I did see something to the effect that every significant physical aspect of the RD-180 has been copied.So in other words, you might be able to use an RD-180 in simulations. Not sure whether that helps.
...Though I first suggested it as fantasy, I think something much easier than this would be to replace RS-25 with J-2X, strengthen the core with strong-backs, and place it on top of BFR (S1 of MCT). What was the SLS core becomes the most powerful ever US atop the most powerful ever S1.You get a stupendous initial boost from a reusable S1. Your SLS based US is air startable with an engine that has been fully developed and paid for. No longer needed are RS-25E, advanced boosters, or EUS. The SLS core could likely handle the remainder of ΔV to Earth orbit, TLI, LOI, and finish as a crasher stage for a robust Lunar lander. I know it won't fit in the VAB, but it would mean NASA could simply lease S1 service from SpaceX, eliminate development of the three components listed above, begin developing other needed systems, and perhaps focus primarily on Luna while SpaceX focuses primarily on Mars.Some have stated it would be better to build a Metholox US whose diameter matches the S1. The thing is, SpaceX is not planning that, but the BFS instead. This would be a way to leverage what is already in design by both entities. NASA is building the SLS core, but can't afford to do much else at the present time. SpaceX is in the middle of designing Raptor and MCT. Under this scheme, NASA would simple lease S1 launch service on BFR that is headed toward development. NASA could do relatively modest changes to SLS, forget advanced boosters, RS-25E, and EUS, and turn its attention to a lander. Mars is explored by SpaceX with some help from NASA and Luna is explored by NASA with some help from SpaceX.....
No need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.
Quote from: Zed_Noir on 03/18/2016 03:29 pmNo need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.That would require extra refueling launches. This approach also acknowledges the realpolitik of keeping pork flowing to particular states/districts and satisfying high ranking congresspersons.
Quote from: TomH on 03/18/2016 03:35 pmQuote from: Zed_Noir on 03/18/2016 03:29 pmNo need. Adopt the the rumored SX Raptor powered reusable upper stage as a lander. Just stick a HAB or cargo module on top of the upper stage.That would require extra refueling launches. This approach also acknowledges the realpolitik of keeping pork flowing to particular states/districts and satisfying high ranking congresspersons.Might be a bit of misunderstanding. The SX upper stage devised lander will go on top of your fantasy stack. So the lander's prop tanks should be fully filled for Lunar descend from LLO.
I just think that modifying the core to accommodate having a booster under pushing rather than above it pulling probably would be about as extensive as switching it to kerolox or whatever, by the time it's all said and done.
...just switching to use MCT outright and buying launch services from SpaceX and cancelling SLS and Orion....will likely be what happens eventually anyway, but if it happened sooner, it could mean MCT is ready to fly sooner too.)
Might be a bit of misunderstanding. The SX upper stage devised lander will go on top of your fantasy stack. So the lander's prop tanks should be fully filled for Lunar descend from LLO.
Quote from: Lobo on 03/18/2016 04:46 pmI just think that modifying the core to accommodate having a booster under pushing rather than above it pulling probably would be about as extensive as switching it to kerolox or whatever, by the time it's all said and done.My friend Lobo!I remember the time when you proposed ganging three F9s with strongbacks and sticking a cluster on each side of SLS to act as the boosters. That's actually where I got the idea that I stated above of just strengthening the sides of the core with strongbacks only, no actual modifications of the walls. If clustering a trio of F9s on each side with strongbacks is possible, then it seems a strongback alone for structural reinforcement should also be possible.I'm trying to think of the cheapest way to preserve certain congressmen's pork interests and yet still make it possible for NASA to do something with what otherwise is a boondoggle.
Quote from: Lobo on 03/18/2016 04:46 pm...just switching to use MCT outright and buying launch services from SpaceX and cancelling SLS and Orion....will likely be what happens eventually anyway, but if it happened sooner, it could mean MCT is ready to fly sooner too.)This is what I expect will indeed happen. OTOH, those particular congresspersons have proven remarkably able to keep this pork line flowing. Though far from ideal, this preserves the pork currently in place, but perhaps could allow NASA to actually cook that pig and serve some food.
Steven, if you have any interest in running calculations on this monster, I would be greatly interested in the results.
What will be the steady state SLS flight rate?SLS Block 2 will be 50% more massive than shuttle.Shuttle launched on average about 4 times a year. So SLS should launch at least 2 to 3 times a year.But I have heard on many occasions that SLS will be launched once every two years, or maybe but unlikely once a year.This does not make sense to me. Why would the SLS launch rate be so low?