Quote from: AncientU on 09/13/2015 02:16 pmI wouldn't be surprised to see horizontal landing based upon Shuttle, X-37B, and Dreamchaser technology... would also be way to protect the vac engine and nozzle. Sierra Nevada would jump at a partnership.I would not be surprised, I would be shocked. This is SpaceX and they use landing tech they can use on Mars. No way they do horizontal landing.
I wouldn't be surprised to see horizontal landing based upon Shuttle, X-37B, and Dreamchaser technology... would also be way to protect the vac engine and nozzle. Sierra Nevada would jump at a partnership.
By this logic if a Methalox FH reusable upper stage is developed I expect it to have methane RCS and super RCS (ie landing engines).
In the 1950's von Braum and many others foresaw a slower approach to space exploration that involved first orbiting the Earth and successfully returning, then building one or more orbital habitats, then assembling lunar and Martian expeditions at these stations and having those expeditions in turn start by digging in and setting up bases. While the actual cost to do this would have been high it would have seen an economy of scale with the numbers of common systems being built.Musk has a stated goal that includes making that economy of scale exist so that his goal of sustainable of Earth settlement happens. If there is to be a new 2nd stage for the Falcon family, it needs to be part of that, and any development that happens for it would also have to translate to the next family. Falcon 1 saw the Merlin (and saw it evolve fairly significantly - 3 versions). While I can't rule out a Raptor FH 2nd stage, nor can I rule out a ~5meter Raptor 1st stage, statements by SpaceX (Musk, Shotwell, etc) all suggest I should.
I just hope that SX has sufficient R&D money to develop its satellite constellation, re-useable cores and Raptor engine never mind extra for exotic F9 2nd stages. Hardware engineering & prototyping is expensive.
Quote from: nadreck on 09/13/2015 03:54 pmIn the 1950's von Braum and many others foresaw a slower approach to space exploration that involved first orbiting the Earth and successfully returning, then building one or more orbital habitats, then assembling lunar and Martian expeditions at these stations and having those expeditions in turn start by digging in and setting up bases. While the actual cost to do this would have been high it would have seen an economy of scale with the numbers of common systems being built.Musk has a stated goal that includes making that economy of scale exist so that his goal of sustainable of Earth settlement happens. If there is to be a new 2nd stage for the Falcon family, it needs to be part of that, and any development that happens for it would also have to translate to the next family. Falcon 1 saw the Merlin (and saw it evolve fairly significantly - 3 versions). While I can't rule out a Raptor FH 2nd stage, nor can I rule out a ~5meter Raptor 1st stage, statements by SpaceX (Musk, Shotwell, etc) all suggest I should.Credible estimates of the Raptor sea level nozzle diameter are 1.6-1.8m from the previous thread. 5 meters is not big enough for seven such nozzles; Nine nozzles would require something on the order of 7-8m.A 2-nozzle or 3-nozzle launch vehicle would, as I understand it, not be able to land on its main engines.
Quote from: Burninate on 09/13/2015 03:59 pmQuote from: nadreck on 09/13/2015 03:54 pmIn the 1950's von Braum and many others foresaw a slower approach to space exploration that involved first orbiting the Earth and successfully returning, then building one or more orbital habitats, then assembling lunar and Martian expeditions at these stations and having those expeditions in turn start by digging in and setting up bases. While the actual cost to do this would have been high it would have seen an economy of scale with the numbers of common systems being built.Musk has a stated goal that includes making that economy of scale exist so that his goal of sustainable of Earth settlement happens. If there is to be a new 2nd stage for the Falcon family, it needs to be part of that, and any development that happens for it would also have to translate to the next family. Falcon 1 saw the Merlin (and saw it evolve fairly significantly - 3 versions). While I can't rule out a Raptor FH 2nd stage, nor can I rule out a ~5meter Raptor 1st stage, statements by SpaceX (Musk, Shotwell, etc) all suggest I should.Credible estimates of the Raptor sea level nozzle diameter are 1.6-1.8m from the previous thread. 5 meters is not big enough for seven such nozzles; Nine nozzles would require something on the order of 7-8m.A 2-nozzle or 3-nozzle launch vehicle would, as I understand it, not be able to land on its main engines.Scaling up to say 5.2m while maintaining V1.1 fineness and going to methalox propellant would suggest a take off mass around 1,200 - 1,400t which would be best served by 7 Raptors in the 225t thrust range. As long as you were not planning on strapping 3 of these together to make a 'heavy' version the 7 engines could be arranged similar to the 9 on an F9 with the outboard engines having about half their diameter outside the cross section of the core.
Huh!Could I get a second opinion on whether this 'outboard engine' arrangement, with nozzles protruding beyond the edge of the vehicle, is workable? It would make a separate design exercise I've been doing that much easier.
Could I get a second opinion on whether this 'outboard engine' arrangement, with nozzles protruding beyond the edge of the vehicle, is workable? It would make a separate design exercise I've been doing that much easier.
Quote from: Burninate on 09/13/2015 04:20 pmHuh!Could I get a second opinion on whether this 'outboard engine' arrangement, with nozzles protruding beyond the edge of the vehicle, is workable? It would make a separate design exercise I've been doing that much easier.Falcon 9 1.0 with the tic tac toe engine arrangement did just that, if not so extreme.
Quote from: Burninate on 09/13/2015 04:20 pmCould I get a second opinion on whether this 'outboard engine' arrangement, with nozzles protruding beyond the edge of the vehicle, is workable? It would make a separate design exercise I've been doing that much easier.Look at the F1 arrangement on the Saturn V
1) Having two different fuel types on one rocket complicates launch operations.
2) Having a completely new engine type for just one upper stage would mean considerable cost increases, due:2.1) Cost to design an engine they would not otherwise need2.2) Cost to prepare the manufacturing of an engine they would not otherwise need2.3) Manufacturing only small number of those new upper stage engines and not being able to share most parts with first stage engine would mean considerably higher unit costs for the engines(compared to Merlin 1dVac)
Why is everyone assuming reusability? I thought that had been given up on Falcon S2.
Quote from: hkultala on 09/12/2015 08:29 am1) Having two different fuel types on one rocket complicates launch operations.The majority of LV use two different types of fuel on each stage. Quote from: hkultala on 09/12/2015 08:29 am2) Having a completely new engine type for just one upper stage would mean considerable cost increases, due:2.1) Cost to design an engine they would not otherwise need2.2) Cost to prepare the manufacturing of an engine they would not otherwise need2.3) Manufacturing only small number of those new upper stage engines and not being able to share most parts with first stage engine would mean considerably higher unit costs for the engines(compared to Merlin 1dVac)SpaceX is already developing a methane engine. It isn't a huge leap to expect that SpaceX might want to switch to a Methane upper stage engine. If you combine 3rd printing, Modern CNC machines, and 2nd stage re-usability, a different upper stage from the boost stage engine doesn't have to equal considerable higher costs.
Quote from: hkultala on 09/12/2015 08:29 am1) Having two different fuel types on one rocket complicates launch operations.The majority of LV use two different types of fuel on each stage.
Quote from: hkultala on 09/12/2015 08:29 am2) Having a completely new engine type for just one upper stage would mean considerable cost increases, due:2.1) Cost to design an engine they would not otherwise need2.2) Cost to prepare the manufacturing of an engine they would not otherwise need2.3) Manufacturing only small number of those new upper stage engines and not being able to share most parts with first stage engine would mean considerably higher unit costs for the engines(compared to Merlin 1dVac)SpaceX is already developing a methane engine. It isn't a huge leap to expect that SpaceX might want to switch to a Methane upper stage engine. If you combine 3rd printing, Modern CNC machines, and 2nd stage re-usability, a different upper stage from the boost stage engine doesn't have to equal considerable higher costs.
Ok a little bit of history on the discussion of CommX. (See the various SpaceX satelite threads for more details of the discussion on costs, and engineering)1) Satelites will weigh <180kg each.2) As many as 128 of them can be packed into a dispenser that will even fit in the current F9/FH size fairing. Weight with dispenser about 30-32mt 3) Cost of manufacture of each sat estimated at $500K4) Target cost of launch of each sat at $500K ($70M on an FHR including cost of the expendable dispenser)5) Cost to deploy 1st generation CommX (4096 sats and 32 launches) = $4-5BNow for the economics of a reusable US.1) current cost of the US is ~$16M.2) reusing the stage will save ~$10M3) over the deployment of using the FHR with this reusable US is $320M (32 FHR flights dispensing 128 sats each)Question is $320M enough to equal the development cost of this reusable US?Otherwise the business case will not close for this upgrade within the lifetime of the use of F9 and FH before the BFR/MCT take over the delivery of large quantity of sats, people and bulk cargo (including prop) at almost the same cost per flight as the FHR with 3 times the payload.2nd generation CommX sats would be deployed in the 2025 or later timeframe by which time BFR/MCT will be flying. A 50% heavier sat with 3-4X the data rate throughput upgrade (smaller spot sizes) launch at 256 of them at a time for half the cost each $250K will reduce the cost of deployement of this 2nd generation of CommX sats to $3-5B a savings of $1B. F9R or FHR cannot compete economically with this no mater what you do to the US.If BFR/MCT will be significantly delayed then there may be an economic incentive to make the current F9/FH US reusable. But that is the only thing that would make such a project even considerable.