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modemeagle
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« Reply #240 on: 08/19/2012 02:26 AM » |
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Can the RS-68 be air started or will the CBC need to use two J-2s instead?
It would need to be modified, requiring a development effort. A pair of J-2X engines would be a better match than RS-68 for a serial-staged design.
Going back today and taking the time to do the parallel burn calculations, I've figured that a Delta 4 CBC core topped by a standard Delta 4 Heavy 5-meter upper stage, boosted by four Atlas 5 CCBs with the core burning throttled down to 58% much of the way up, would lift 55 tonnes to LEO at least. At liftoff this conglomeration would produce 1,861 tonnes (4.1 Mlbf) of thrust. The boosters would have to throttle near the end of their burns to keep g-forces down.
A slight upper stage enlargement, from 30.5 tonnes to 36 tonnes GLOW, would improve performance to 60 tonnes to LEO.
With no upper stage, this rocket might lift nearly 35 tonnes to LEO, but it would be a hot, fast ride on a rocket that would probably cost $1.0 to 1.5 billion.
- Ed Kyle
I crunched the numbers on this earlier today. With two CCB and using an SSME on the CBC, no upper stage, I am finding 32 metric tons. With four CCB, 55 metric tons. With the original CBC running an RS-68A I am finding it needs an upper stage. I'll try the dual J-2X later, although that would cost more than the single SSME.
Here is my simulation without upper stage. * only to be used as a guide, not final analysis
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oldAtlas_Eguy
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« Reply #243 on: 08/19/2012 09:53 PM » |
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The old link to the Steve Cook story is dead.
Here it is again.
http://www.wtov9.com/news/ap/aerospace/nasa-might-use-saturn-v-engines-on-mars-rocket/nP6j7/
18ft diameter tank built in Huntsville? 
The tank "will be the biggest structure built for a launch vehicle in Huntsville since Saturn Apollo," Cook said. Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's: 100mt non-crossfeed 130mt crossfeed Althogh the payload can easily be 20mt lower due to a lot of odds and ends which are unknown and which are needed to produce an optimized vehicle.
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TomH
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« Reply #244 on: 08/19/2012 11:42 PM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H 2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H 2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
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Downix
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« Reply #245 on: 08/20/2012 02:29 AM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
And losing a ton of performance, unless you are limiting us to LEO-only. SLS being hydrolox will crush this to TLI.
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TomH
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« Reply #246 on: 08/20/2012 04:30 AM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
And losing a ton of performance, unless you are limiting us to LEO-only. SLS being hydrolox will crush this to TLI.
O.K. I am no rocket scientist, and I know that you are. Here's what I honestly don't get. Assuming that any earth departure stage on top of this theoretical rocket or atop SLS is HydroLox, (the US mentioned above was for reaching LEO, not an EDS) powered by RL-10 class engines, and that this EDS is part of the 130 mT placed in LEO prior to TLI, why would it matter which of the two rockets places the 130 mT into initial LEO?
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Downix
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« Reply #247 on: 08/20/2012 05:05 AM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
And losing a ton of performance, unless you are limiting us to LEO-only. SLS being hydrolox will crush this to TLI.
O.K. I am no rocket scientist, and I know that you are. Here's what I honestly don't get. Assuming that any earth departure stage on top of this theoretical rocket or atop SLS is HydroLox, (the US mentioned above was for reaching LEO, not an EDS) powered by RL-10 class engines, and that this EDS is part of the 130 mT placed in LEO prior to TLI, why would it matter which of the two rockets places the 130 mT into initial LEO?
You'd be increasing costs then. You now have not saved any money, due to retaining of the hydrolox, while you did not gain the advantage of hydrolox for the upper part of the burn. Your kerolox core would stage at a lower delta-v than a comparable hydrolox system, which means you would need a more capable EDS. Compare the J-246 to the Saturn V. The J-246 could throw about 50% more to TLI, despite having less thrust on every stage. Or use the Energia, which again could throw more to TLI despite having less thrust. The point of an all-kerolox design is to save on costs. Once you put Hydrolox into the mix, the cost savings are gone, and you'd be smart to exploit the Hydrolox's strength. Using the hypothetical Delta IV core w/ US and Atlas V boosters, you can get performance greater than either two alone, ~34 metric tons to LEO, or ~9 tons to TLI (AVH has LEO of ~28 metric tons, TLI of ~7 metric tons, for comparison). There is a reason why.
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RocketmanUS
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« Reply #248 on: 08/20/2012 05:33 AM » |
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SLS EDS is not part of the US ( CPS as EDS )
Using the three core system we still can launch it with just one core for lighter payloads, higher flight rates.
Does not need both F-1 and SSME's.
EDS could be the common US planned for Delta IV and Atlas V ( ACES or wide body Centaur ). It is payload to orbit, not needed for the orbital burn.
SLS only advantage is a wider payload fairing and I don't see a need for that wide of a fairing.
If they do replace the SRB's with LRB's then best to just go with the FX concept from SpaceX ( a larger Delta IV/H ).
For the low flight rates in the triple core they could have more flights to fill in with the single core.
And the single core both stage RP-1/LOX would get what mass to LEO?
For GTO there should soon be a reusable space tug plus a type of depot ( low cost and expendable )
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Downix
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« Reply #249 on: 08/20/2012 06:26 AM » |
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SLS EDS is not part of the US ( CPS as EDS )
Using the three core system we still can launch it with just one core for lighter payloads, higher flight rates.
Does not need both F-1 and SSME's.
EDS could be the common US planned for Delta IV and Atlas V ( ACES or wide body Centaur ). It is payload to orbit, not needed for the orbital burn.
SLS only advantage is a wider payload fairing and I don't see a need for that wide of a fairing.
If they do replace the SRB's with LRB's then best to just go with the FX concept from SpaceX ( a larger Delta IV/H ).
For the low flight rates in the triple core they could have more flights to fill in with the single core.
And the single core both stage RP-1/LOX would get what mass to LEO?
For GTO there should soon be a reusable space tug plus a type of depot ( low cost and expendable )
Ok, I went over this, assuming an AJ-26 US (as the sole air-startable US kerolox engine available from a US company: Single Stick: 12 metric tons Heavy configuration: 45 metric tons Now, let's have fun, a Delta IV using these as boosters for Heavy: 58 metric tons Eliminate the upper stage: 49 metric tons Same, now with a single SSME instead of RS-68, no US: 61 metric tons In no configuration is the pure-kerolox version able to match the kero/hydro parallel staged configuration, even if you eliminate a stage on the kero/hydro setup.
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MP99
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« Reply #250 on: 08/20/2012 12:53 PM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
And losing a ton of performance, unless you are limiting us to LEO-only. SLS being hydrolox will crush this to TLI.
If block 2 uses multiple J-2Xs, it will basically be LEO-only. Requires CPS or SEP stage for TLI, etc. This is the advantage of Block 1B. cheers, Martin
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WulfTheSaxon
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« Reply #251 on: 08/20/2012 03:27 PM » |
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Put three of those 5.5m cores together with an US and what mass to LEO would we get ( US RP-1/LOX or LH/LOX )?
Quick estimate for RP-1 US using a pair of SpaceX MVacD's:
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130mt crossfeed
In other words, replace the SLS core with another booster and add the US, get the same mass to LEO. May as well just build this booster and use 3 of it per launch and not build the H2lOx core. The 3 CCBs and the US all would use RP1 and lOx, no H2 needed. More efficiency on one assembly line (plus the possibility of additional launches using a single core) while closing the very slow SLS core line. Hmmmm.
And losing a ton of performance, unless you are limiting us to LEO-only. SLS being hydrolox will crush this to TLI.
If block 2 uses multiple J-2Xs, it will basically be LEO-only. Requires CPS or SEP stage for TLI, etc. This is the advantage of Block 1B.
cheers, Martin
How so? I get fantastic payload through TLI with an F-1A Block 2 and 3× J-2X US. Or are you suggesting that a large upper stage would never be built?
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Lobo
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« Reply #252 on: 08/20/2012 06:11 PM » |
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Your argument does not add up. By this statement, either the Atlas V or Delta IV could not lift off the pad. They obviously do, and so would this.
I would not do it, not anywhere near the most efficient EELV-derived solution.
Ok, I'll bite. What -is- the most efficient EELV-derived solution then?
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Lobo
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« Reply #253 on: 08/20/2012 06:17 PM » |
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Can the RS-68 be air started or will the CBC need to use two J-2s instead?
It would need to be modified, requiring a development effort. A pair of J-2X engines would be a better match than RS-68 for a serial-staged design.
Going back today and taking the time to do the parallel burn calculations, I've figured that a Delta 4 CBC core topped by a standard Delta 4 Heavy 5-meter upper stage, boosted by four Atlas 5 CCBs with the core burning throttled down to 58% much of the way up, would lift 55 tonnes to LEO at least. At liftoff this conglomeration would produce 1,861 tonnes (4.1 Mlbf) of thrust. The boosters would have to throttle near the end of their burns to keep g-forces down.
A slight upper stage enlargement, from 30.5 tonnes to 36 tonnes GLOW, would improve performance to 60 tonnes to LEO.
With no upper stage, this rocket might lift nearly 35 tonnes to LEO, but it would be a hot, fast ride on a rocket that would probably cost $1.0 to 1.5 billion.
- Ed Kyle
Pricetag aside, what woudl that rocket do with 6 boosters rather than 4? as both the RD-180 and RS-68 can throttle, I assume they can be throttled back to reduce g's during ascent if necessary? And would the price tag come down with the increased volume of the EELV cores? I think that's the assumtion here with looking at LV's based on existing EELV hardware.
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Lobo
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« Reply #254 on: 08/20/2012 06:27 PM » |
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I crunched the numbers on this earlier today. With two CCB and using an SSME on the CBC, no upper stage, I am finding 32 metric tons. With four CCB, 55 metric tons. With the original CBC running an RS-68A I am finding it needs an upper stage. I'll try the dual J-2X later, although that would cost more than the single SSME.
I think the idea is that we don't won't to need an upper stage to get to LEO, hence the D4 sustain stage. Otherwise, we could just use all Atlas V's on the first stage, with a large 2nd stage to get to LEO. What would be the issues with either air starting the RS-68? Or keeping it throttled back? Or will it just burn up too much fuel at it's lowest throttle point? Going with RS-25 would then loose the advantage of commanlity with "off-the-shelf" EELV hardware, even if it's the more ideal engine for the purpose. As an aside, what about a cluster of RL-10's on the D4 core that could be air lit? Not quite off-the-shelf with EELV, but it would be an active engine used with the EELV program. If EELV derived were used instead of SLS, then the need for RS-25 goes away.
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