Quote from: ThereIWas3 on 05/30/2016 04:01 pmAn affordable launcher that can lift smaller payloads is more useful than a big one that is too expensive to operate. In times of tight money, you can scale back to fewer loads, but at least you are making some progress. I disagree with your assertion that SLS is "too expensive to operate". It is being designed to operate on less than the Shuttle budget, involving far fewer workers. Shuttle flew for three decades. - Ed Kyle
An affordable launcher that can lift smaller payloads is more useful than a big one that is too expensive to operate. In times of tight money, you can scale back to fewer loads, but at least you are making some progress.
SLS (and NASA) is not in competition with SpaceX.
Quote from: Dasun on 05/30/2016 09:10 pmSLS (and NASA) is not in competition with SpaceX.Except that SLS *is* in competition with SpaceX.By law, NASA can't compete with commercially available products.As soon as FH flies, some difficult questions will be asked, "why do we pay these insane money for SLS?"
Sigh, and SLS is not competing for missions with FH, Dragon, CST-100 and Dream Chaser!!!
SLS was designed, based on NASA requirements...
...to support likely Mars mission architectures at relatively low flight rates.
...in fact SpaceX is just another aerospace contractor that can meet NASA needs.
Congress seems to have some firm ideas what SLS is going to do...
...lets us see if the money flows and the next POTUS agrees.
Quote from: AncientU on 05/30/2016 02:45 pmFirst, SLS is implied as the 'world's most capable rocket.' FH (with either the 1.7M or 1.9Mlbf thrust booster version) will lift more payload than SLS's first 'block' as shown by your and others' calculations. This is simply incorrect. SLS Block 1 will boost 24.5 tonnes toward the Moon. (It could, if needed, lift more than 90 tonnes to low earth orbit (70 tonnes is an artifact of the old SLS Block 0 design), but SLS is never going to LEO so that number is irrelevant.) Falcon Heavy, even in full-expendable mode, would boost probably about 15 tonnes (plus or minus) toward the Moon. (Falcon Heavy is also listed at only 54.4 tonnes to LEO in full-expendable mode.)It would take three fully-expendable Falcon Heavies to match the payload of one SLS Block 1B trans-Mars. It would take four Falcon Heavies to match one SLS Block 2. I expect that Falcon Heavy and/or others like it will be needed to support deep-space missions, but the missions will be built around the unparalleled deep space throw-weight offered by SLS. - Ed Kyle
First, SLS is implied as the 'world's most capable rocket.' FH (with either the 1.7M or 1.9Mlbf thrust booster version) will lift more payload than SLS's first 'block' as shown by your and others' calculations.
54.4 tonnes to LEO is simply not consistent with three 1.7-1.9Mlbf stages -- that's 2/3rds to 3/4ths of Saturn V liftoff thrust -- even a single core (skinny) F9 outperforms Saturn V in PMF (and delivers double the PMF of SLS). FH outperforms F9 by a significant margin. Then cross feed and Raptor powered second stage can be added just as Block 2 will eventually get a better second stage and new boosters.
Quote from: gospacex on 05/30/2016 09:30 pmQuote from: Dasun on 05/30/2016 09:10 pmSLS (and NASA) is not in competition with SpaceX.Except that SLS *is* in competition with SpaceX.By law, NASA can't compete with commercially available products.As soon as FH flies, some difficult questions will be asked, "why do we pay these insane money for SLS?"For the moment NASA can claim FH does not have a large enough fairing...
The key number is Falcon Heavy's 13.6 tonnes trans-Mars (full-expendable). That's impressive, and can be exploited any number of ways, but it isn't 40 tonnes or 46 tonnes (SLS Block 1B Cargo or SLS Block 2).
When and if BFR starts flying, SLS is dead.
54.4 tonnes is what the manufacturer says Falcon Heavy can do. If would lift half that, give or take, if the booster and first stages were recovered. Your Saturn 5 liftoff thrust comparison doesn't add up because Saturn 5 used high energy liquid hydrogen fueled upper stages. Falcon Heavy uses lower energy hydrocarbon engines on all of its stages. It has to carry a heavier upper stage, relatively speaking, to make up the difference. More liftoff thrust, relatively speaking, is needed to lift the extra mass. The key number is Falcon Heavy's 13.6 tonnes trans-Mars (full-expendable). That's impressive, and can be exploited any number of ways, but it isn't 40 tonnes or 46 tonnes (SLS Block 1B Cargo or SLS Block 2).
Quote from: IRobot on 05/30/2016 09:50 pmQuote from: gospacex on 05/30/2016 09:30 pmQuote from: Dasun on 05/30/2016 09:10 pmSLS (and NASA) is not in competition with SpaceX.Except that SLS *is* in competition with SpaceX.By law, NASA can't compete with commercially available products.As soon as FH flies, some difficult questions will be asked, "why do we pay these insane money for SLS?"For the moment NASA can claim FH does not have a large enough fairing......large enough *for what*? Can NASA point us to a funded payload which can't fit into FH's fairing?
How about projected payloads needed for a Mars mission. That's a more realistic comparison.
Something as large as a lander would need 8.4 m or 10 m fairings.
It will take a combination of SLS and commercial rockets to assemble a Mars mission in a reasonable amount of time.
Or, if SpaceX is successful in their Mars endeavors, NASA can just buy a ride to Mars with them. Regardless, a NASA HLV of any type won't be needed for quite a while to support trips to Mars.
FH does not compete with SLS - It throws much more upstairs !!!! And I think you will be waiting quite awhile for your "difficult" questions to be asked at the appropriate level for influence to happen!!