Quote from: MikeAtkinson on 06/12/2016 04:25 pmWe don't know the development status of MCT. It could be anywhere from a few powerpoints which seem to hang together as an architecture, to having passed PDR (or the SpaceX equivalent) several months ago. About the only thing known in public is that the Raptor has had component level tests which have gone quite well. It is now 8 months since Chris Bergin made that tweet https://forum.nasaspaceflight.com/index.php?topic=38593.0 and things will have moved on a lot since then. Chris has shared some of the information that he received in L2, I cannot say what that is, but just given the fact that things were far enough advanced for Chris to be shown data means that they were far enough advanced for the basic factory and launch site specs to be determined (not the detailed ones, but such things as floor area, overhead crane height, access requirements, thrust levels and landing pad requirements). These are enough to start looking for a factory and launch site, and if they have been at it for 8 months SpaceX probably have a pretty good idea about the possibilities.And to tie it together to other "signs and indicators," for those who have been following the "Where will BFR launch from?" thread, if you look at SpaceX planning on building and launching BFRs in six years, the only place where they are currently beginning construction on new facilities is Boca Chica.If y'all are saying that SpaceX needs to be building the BFR factory and launch facilities right now, well -- maybe they are.
We don't know the development status of MCT. It could be anywhere from a few powerpoints which seem to hang together as an architecture, to having passed PDR (or the SpaceX equivalent) several months ago. About the only thing known in public is that the Raptor has had component level tests which have gone quite well. It is now 8 months since Chris Bergin made that tweet https://forum.nasaspaceflight.com/index.php?topic=38593.0 and things will have moved on a lot since then. Chris has shared some of the information that he received in L2, I cannot say what that is, but just given the fact that things were far enough advanced for Chris to be shown data means that they were far enough advanced for the basic factory and launch site specs to be determined (not the detailed ones, but such things as floor area, overhead crane height, access requirements, thrust levels and landing pad requirements). These are enough to start looking for a factory and launch site, and if they have been at it for 8 months SpaceX probably have a pretty good idea about the possibilities.
Quote from: the_other_Doug on 06/12/2016 05:39 pmQuote from: MikeAtkinson on 06/12/2016 04:25 pmWe don't know the development status of MCT. It could be anywhere from a few powerpoints which seem to hang together as an architecture, to having passed PDR (or the SpaceX equivalent) several months ago. About the only thing known in public is that the Raptor has had component level tests which have gone quite well. It is now 8 months since Chris Bergin made that tweet https://forum.nasaspaceflight.com/index.php?topic=38593.0 and things will have moved on a lot since then. Chris has shared some of the information that he received in L2, I cannot say what that is, but just given the fact that things were far enough advanced for Chris to be shown data means that they were far enough advanced for the basic factory and launch site specs to be determined (not the detailed ones, but such things as floor area, overhead crane height, access requirements, thrust levels and landing pad requirements). These are enough to start looking for a factory and launch site, and if they have been at it for 8 months SpaceX probably have a pretty good idea about the possibilities.And to tie it together to other "signs and indicators," for those who have been following the "Where will BFR launch from?" thread, if you look at SpaceX planning on building and launching BFRs in six years, the only place where they are currently beginning construction on new facilities is Boca Chica.If y'all are saying that SpaceX needs to be building the BFR factory and launch facilities right now, well -- maybe they are.In my opinion Boca Chica is not suitable for the MCT manufacturing site. Other places in the Brownsville area maybe. That we have not seen an environmental impact statement is perhaps an indication that SpaceX have found a site that does not need one (existing large factory or facility?) or that they think an environmental impact statement will be a formality (contaminated land, brownfield site?).If Musk thinks 2024 MCT is possible, then he must see a way forward, but I have no clue about what that path is.
Also, the "local manufacturing site" is likely going to be at least partially an assembly site. They likely won't want to truck BFR stages around -- too large -- but I bet the engines and whatever serves as an octaweb (the thrust and plumbing structures) could still be made at one primary site, like Hawthorne, and shipped out to the tank manufacture/stage assembly sites.It's not like there would be no manufacturing happening near the BFR launch sites, but the only things that, it would seem, are required to be built near the launch site are the tanks/stage structures. A lot of pieces will be sub-assemblies that are manufactured elsewhere and shipped to the BFR sites in by conventional means...
Quote from: the_other_Doug on 06/12/2016 06:28 pmAlso, the "local manufacturing site" is likely going to be at least partially an assembly site. They likely won't want to truck BFR stages around -- too large -- but I bet the engines and whatever serves as an octaweb (the thrust and plumbing structures) could still be made at one primary site, like Hawthorne, and shipped out to the tank manufacture/stage assembly sites.It's not like there would be no manufacturing happening near the BFR launch sites, but the only things that, it would seem, are required to be built near the launch site are the tanks/stage structures. A lot of pieces will be sub-assemblies that are manufactured elsewhere and shipped to the BFR sites in by conventional means...Possibly, but Hawthorne will be at or near capacity with F9/FH, as reusability reduces the need for first stages, an increased flight rate would increase second stage production*. It is much easier to build on a greenfield site than trying to cram production for completely different (and bigger elements). That said the avionics is probably going to be similar so could be produced at Hawthorne with little difficulty.[*] in future a reusable raptor based second stage might reduce Hawthorne production requirements, but probably not until the early 2020's.
Quote from: philw1776 on 06/12/2016 01:00 pmQuote from: Robotbeat on 06/12/2016 03:13 amQuote from: philw1776 on 06/12/2016 12:37 amQuote from: Impaler on 06/11/2016 11:40 pmphilw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.2 good observations.First, the tanks. You're on target. What I did was simply compute volume and weight of cylinders to estimate the mass of the rocket, etc. I do NOT mean that the propellant tank is really18m for example, My bad. There is a big O2 tank and a separate methane tank. They have rounded ends in reality, making them longer. A 15m wide rocket does not really have a 15m wide tank. Again the simplification is used to estimate mass, thrust, etc. and not length of rocket which however I believe will still be squat under 100m. Engines, interstage, whatever. I needed to add prose to be clear on that.Mike A observed that there is excess Km/sec capacity in that the craft can arrive in LEO with extra tons of fuel. I believe there will be an upper stage BFS configuration used as a fuel truck with less dry mass. I get 8-10 refueling trips for one 120 day or less transit. I think that's too many refueling trips. Rest assured SX has a much better solution as I'm just a EE and not an aerospace engineer.One final point. This is a brute force all chemical approach. SX will be more imaginative.Your dry mass is too high.4.5% for 1st stage may be high. I'm in the camp of those who say minimum 6 legs. I hope it's high, but I think the BFR has to be more robust, read heavier, if it really is a quick turn around, only very minor refurbishment vehicle. I think today's F9 has unresolved issues there.As to the BFS, with all the exotica of engines placed high for Mars landing & takeoff, cargo arrangement complications and robust TPS that lasts many re-entries at interplanetary velocities, I don't buy the dry mass under 100mT thinking for such a complex, lightly serviced vehicle.And so you have 14 refuelings. That's not going to happen. That is definitely not what SpaceX is planning. Your dry masses are too high.
Quote from: Robotbeat on 06/12/2016 03:13 amQuote from: philw1776 on 06/12/2016 12:37 amQuote from: Impaler on 06/11/2016 11:40 pmphilw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.2 good observations.First, the tanks. You're on target. What I did was simply compute volume and weight of cylinders to estimate the mass of the rocket, etc. I do NOT mean that the propellant tank is really18m for example, My bad. There is a big O2 tank and a separate methane tank. They have rounded ends in reality, making them longer. A 15m wide rocket does not really have a 15m wide tank. Again the simplification is used to estimate mass, thrust, etc. and not length of rocket which however I believe will still be squat under 100m. Engines, interstage, whatever. I needed to add prose to be clear on that.Mike A observed that there is excess Km/sec capacity in that the craft can arrive in LEO with extra tons of fuel. I believe there will be an upper stage BFS configuration used as a fuel truck with less dry mass. I get 8-10 refueling trips for one 120 day or less transit. I think that's too many refueling trips. Rest assured SX has a much better solution as I'm just a EE and not an aerospace engineer.One final point. This is a brute force all chemical approach. SX will be more imaginative.Your dry mass is too high.4.5% for 1st stage may be high. I'm in the camp of those who say minimum 6 legs. I hope it's high, but I think the BFR has to be more robust, read heavier, if it really is a quick turn around, only very minor refurbishment vehicle. I think today's F9 has unresolved issues there.As to the BFS, with all the exotica of engines placed high for Mars landing & takeoff, cargo arrangement complications and robust TPS that lasts many re-entries at interplanetary velocities, I don't buy the dry mass under 100mT thinking for such a complex, lightly serviced vehicle.
Quote from: philw1776 on 06/12/2016 12:37 amQuote from: Impaler on 06/11/2016 11:40 pmphilw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.2 good observations.First, the tanks. You're on target. What I did was simply compute volume and weight of cylinders to estimate the mass of the rocket, etc. I do NOT mean that the propellant tank is really18m for example, My bad. There is a big O2 tank and a separate methane tank. They have rounded ends in reality, making them longer. A 15m wide rocket does not really have a 15m wide tank. Again the simplification is used to estimate mass, thrust, etc. and not length of rocket which however I believe will still be squat under 100m. Engines, interstage, whatever. I needed to add prose to be clear on that.Mike A observed that there is excess Km/sec capacity in that the craft can arrive in LEO with extra tons of fuel. I believe there will be an upper stage BFS configuration used as a fuel truck with less dry mass. I get 8-10 refueling trips for one 120 day or less transit. I think that's too many refueling trips. Rest assured SX has a much better solution as I'm just a EE and not an aerospace engineer.One final point. This is a brute force all chemical approach. SX will be more imaginative.Your dry mass is too high.
Quote from: Impaler on 06/11/2016 11:40 pmphilw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.2 good observations.First, the tanks. You're on target. What I did was simply compute volume and weight of cylinders to estimate the mass of the rocket, etc. I do NOT mean that the propellant tank is really18m for example, My bad. There is a big O2 tank and a separate methane tank. They have rounded ends in reality, making them longer. A 15m wide rocket does not really have a 15m wide tank. Again the simplification is used to estimate mass, thrust, etc. and not length of rocket which however I believe will still be squat under 100m. Engines, interstage, whatever. I needed to add prose to be clear on that.Mike A observed that there is excess Km/sec capacity in that the craft can arrive in LEO with extra tons of fuel. I believe there will be an upper stage BFS configuration used as a fuel truck with less dry mass. I get 8-10 refueling trips for one 120 day or less transit. I think that's too many refueling trips. Rest assured SX has a much better solution as I'm just a EE and not an aerospace engineer.One final point. This is a brute force all chemical approach. SX will be more imaginative.
philw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.
If y'all are saying that SpaceX needs to be building the BFR factory and launch facilities right now, well -- maybe they are.
Quote from: Robotbeat on 06/12/2016 05:58 pmQuote from: philw1776 on 06/12/2016 01:00 pmQuote from: Robotbeat on 06/12/2016 03:13 amQuote from: philw1776 on 06/12/2016 12:37 amQuote from: Impaler on 06/11/2016 11:40 pmphilw1776: It seems that your design would require 14 refueling flights to be ready for TMI, and then at Mars a staggering amount of propellant to return. I'm incredibly doubtful of these fast LEO departures and direct returns because the launch count necessary to do a mission will run up costs and the Mars surface refueling will stress ISPP too far.Also the vehicle dimensions seem incredibly squat, with tanks that are nearly hockey-pucks in shape, whats the total stack height at launch, it seems like it would be shorter then F9 given the numbers your providing. I don't see the motivation for such squatness unless you believe Raptor has terrible thrust density, but Russian staged combustion hydrocarbon engines (our best analogs for Raptor) have great thrust density which should easily support a vehicle of 80-100 m of height at liftoff.2 good observations.First, the tanks. You're on target. What I did was simply compute volume and weight of cylinders to estimate the mass of the rocket, etc. I do NOT mean that the propellant tank is really18m for example, My bad. There is a big O2 tank and a separate methane tank. They have rounded ends in reality, making them longer. A 15m wide rocket does not really have a 15m wide tank. Again the simplification is used to estimate mass, thrust, etc. and not length of rocket which however I believe will still be squat under 100m. Engines, interstage, whatever. I needed to add prose to be clear on that.Mike A observed that there is excess Km/sec capacity in that the craft can arrive in LEO with extra tons of fuel. I believe there will be an upper stage BFS configuration used as a fuel truck with less dry mass. I get 8-10 refueling trips for one 120 day or less transit. I think that's too many refueling trips. Rest assured SX has a much better solution as I'm just a EE and not an aerospace engineer.One final point. This is a brute force all chemical approach. SX will be more imaginative.Your dry mass is too high.4.5% for 1st stage may be high. I'm in the camp of those who say minimum 6 legs. I hope it's high, but I think the BFR has to be more robust, read heavier, if it really is a quick turn around, only very minor refurbishment vehicle. I think today's F9 has unresolved issues there.As to the BFS, with all the exotica of engines placed high for Mars landing & takeoff, cargo arrangement complications and robust TPS that lasts many re-entries at interplanetary velocities, I don't buy the dry mass under 100mT thinking for such a complex, lightly serviced vehicle.And so you have 14 refuelings. That's not going to happen. That is definitely not what SpaceX is planning. Your dry masses are too high.I don't get 14 refuelings as there is excess capacity in the Km/sec budget which as I responded above to another poster translates into propellant to LEO.The dry mass listed for the BFS is for the Mars transport vehicle. I assume a lesser dry mass for the stripped down tanker to LEO version. I ran the numbers again and get 6-7 tanker trips which I agree is too many for a cost effective campaign. SX will do better.
Yes, I am saying that SpaceX would have to be building the production facilities and launch site right now, and much much more. I don't think there is any evidence of that, and it would all be much too large to keep secret. The factory will have to have a welding tool that is twice the diameter of the vertical welding facility for SLS, and probably much taller. The launch site will have to be qualified for launching a vehicle with twice the thrust of the Saturn-V. The transporter/tilt-up gantry will have to be the length of a football field. The MCT itself will dwarf anything launched to space except for ISS, how could it possibly be far enough along (in total secrecy) to be ready to launch in six years?I'm not saying all of this is impossible. I'm saying that I do think it would be impossible for it all to be ready for launch in six years, with no one hearing a peep of any such activity already under way.I would love to be proven wrong, though.
Any attempt to throw 'computing power' and 'manufacturing' into the same improvement over time comparison is insane and shreds your credibility, the differences are astronomical. Concrete cures at the same speed now as it did in 1950, if anything launch pads and related construction is slower now.
Can I get the numbers for your Tanker dry mass and the expected propellant delivery per trip, I don't see how it can get the BFS vehicle full in the 7 trips your proposing as it would need to offload ~200 mt per flight. Between landing propellant reserves and the dry mass of something that is basically just a 2nd stage I don't think you have that much propellant offload capacity, 10 flights seems more reasonable.All that said I agree even 6-7 refueling flights is not viable, and no amount of Dry mass shaving on RB's part is going to make it work. This is why I belive the only viable architecture is a SEP tug based system in which propellant is pre-placed into high Earth orbit and Mars orbit. The BFS is radically smaller and goes from LEO to EML-2, refuels, goes to Mars, refuels, launches to LMO, refuels and then returns to Earth, all the DeltaV legs are ~4 km/s and allow fast transit times and only requires a vehicle carry around 300 mt of propellant.
So I expect that if the resources and will are there, MCT is **barely** doable to have a first launch in 2022. If you claim it's impossible, you're wrong, it's not impossible. (show your work if you disagree!!). If you claim it's improbable, you're probably right.
Quote from: mme on 06/10/2016 04:56 pmQuote from: starsilk on 06/10/2016 04:02 pma few more teasers before the september reveal:https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...Bold mine.From the article:QuoteThen in 2022, Musk said he hoped to launch what the company now sometimes refers to as the Mars Colonial Transporter, designed to bring a colony to Mars.I'm sorry, but this is nuts somewhat optimistic. You all realize that 2022 is only six years away, right? Regardless of the fact that Dragon v2 hasn't flown yet, and regardless of the fact that FH hasn't flown yet; NOTHING concrete about BFR/MCT has even been released, and Musk is talking about launching one in six years. Six. Years.Six years to get BFR off the ground, literally. To build a factory on the scale of Michoud (only bigger) for fabrication and assembly of BFR and MCT. To build a huge HIF to handle the 12.5m or 15m cores, or heck even to lease one of the VAB high bays and get it fitted out for BFR. To build all of the ground support infrastructure and ground transportation. To get the entire Raptor engine (not just components) off of the drawing board and into the test stands and validated.Heck, you guys are still arguing over where the thing will be built and launched from. Do you think that would really be the case if they were going to be rolling off the assembly line in less than six years?I like SpaceX and they are doing amazing things. But come on. Please apply a little common sense when these kinds of pronouncements are made. Two days after the article was published and three pages on in this thread, I would expect to see some kind of discussion about how that would even be possible.Cheers!
Quote from: starsilk on 06/10/2016 04:02 pma few more teasers before the september reveal:https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...Bold mine.
a few more teasers before the september reveal:https://www.washingtonpost.com/news/the-switch/wp/2016/06/10/elon-musk-provides-new-details-on-his-mind-blowing-mission-to-mars/1 red dragon in 2018, 'at least 2' in 2020, then first flight of MCT in 2022...
Then in 2022, Musk said he hoped to launch what the company now sometimes refers to as the Mars Colonial Transporter, designed to bring a colony to Mars.
Your only allowing 900 m/s for all drag and gravity losses which looks to be too low by around 300 m/s as I can't find any vehicle with total losses of less then around 1200 m/s. That would drop your mass in LEO by about 25 mt and put the flight total at an even 8 which is roughly meeting in the middle of our earlier estimates. Alternatively stretching your vehicle will likely make up the difference.I'm willing to accept 8 as the best estimate for refueling flights needed to perform this all-chemical brute-force mission architecture when performing a fast crew transfer. Do you have an estimate for what could be sent on a slow cargo flight?P.S. Oops, 300 m/s is what you get from Earth rotation so looks good.