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#42
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BFR early next year.
In article ,
says... JF Mezei wrote on Fri, 16 Mar 2018 17:05:50 -0400: On 2018-03-16 03:16, Niklas Holsti wrote: I hope that SLS is also a transitional temporary project, and that BFR will replace it. In this ephemeral role, too, Falcon Heavy competes with SLS. Since SLS has no commercial goals, has limited set of test flights with no planned use beyond one crewed flight around the moon, it is not in any competition except for sucking up government funding away from from more productive uses. I'm sure we've covered this before. While of course stuff out more than half a dozen years tends to get tentative, there are certainly 'planned uses' for SLS beyond one flight around the Moon. That flight is EM-2 (EM-1 is the same mission but unmanned) currently scheduled for 2022. I see 9 more missions planned after that, mostly involved with putting together the Lunar Orbital Platform - Gateway. Is any of this sounding at all familiar to you or have you once again lost all memory of anything that was told to you before lunch? I don't believe that date for EM-2. NASA recently decided to not build a new MLP for EM-2 and instead modify the one to be used for EM-1. This means they simply can't shorten the 33 month gap between EM-1 and EM-2. They really can't start the MLP modifications until after EM-1 flies. So EM-2 will keep slipping to the right by the amount that EM-1 slips to the right. NASA no longer seeking to develop second mobile launcher for SLS by Jeff Foust ? February 28, 2018 http://spacenews.com/nasa-no-longer-...second-mobile- launcher-for-sls/ If EM-1 slips into 2020, as some sites are reporting, I don't see how EM-2 could realistically fly by 2022 with a minimum of 33 months between them. NASA expects first Space Launch System flight to slip into 2020 November 20, 2017 Stephen Clark https://spaceflightnow.com/2017/11/2...-space-launch- system-flight-to-slip-into-2020/ SLS slips are constant and always moving to the right. I have zero faith in the 2022 date for EM-2. Between now and EM-2 we're looking at about $15 to $18 billion to be spent on SLS/Orion (depending on when it actually flies). That does not include any money spent before today, only money we're going to spend. It's absurd how much we're spending on a vehicle that will almost certainly be obsolete before it starts flying "routinely" at a cadence of at most 2 flights per year at a cost to the US taxpayer of well over $1 billion a flight. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#43
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BFR early next year.
Jeff Findley wrote on Sat, 17 Mar 2018
10:04:19 -0400: In article , says... JF Mezei wrote on Fri, 16 Mar 2018 17:05:50 -0400: On 2018-03-16 03:16, Niklas Holsti wrote: I hope that SLS is also a transitional temporary project, and that BFR will replace it. In this ephemeral role, too, Falcon Heavy competes with SLS. Since SLS has no commercial goals, has limited set of test flights with no planned use beyond one crewed flight around the moon, it is not in any competition except for sucking up government funding away from from more productive uses. I'm sure we've covered this before. While of course stuff out more than half a dozen years tends to get tentative, there are certainly 'planned uses' for SLS beyond one flight around the Moon. That flight is EM-2 (EM-1 is the same mission but unmanned) currently scheduled for 2022. I see 9 more missions planned after that, mostly involved with putting together the Lunar Orbital Platform - Gateway. Is any of this sounding at all familiar to you or have you once again lost all memory of anything that was told to you before lunch? I don't believe that date for EM-2. NASA recently decided to not build a new MLP for EM-2 and instead modify the one to be used for EM-1. This means they simply can't shorten the 33 month gap between EM-1 and EM-2. They really can't start the MLP modifications until after EM-1 flies. So EM-2 will keep slipping to the right by the amount that EM-1 slips to the right. NASA no longer seeking to develop second mobile launcher for SLS by Jeff Foust ? February 28, 2018 http://spacenews.com/nasa-no-longer-...second-mobile- launcher-for-sls/ If EM-1 slips into 2020, as some sites are reporting, I don't see how EM-2 could realistically fly by 2022 with a minimum of 33 months between them. NASA expects first Space Launch System flight to slip into 2020 November 20, 2017 Stephen Clark https://spaceflightnow.com/2017/11/2...-space-launch- system-flight-to-slip-into-2020/ NASA is managing to a launch of EM-1 just before Christmas of 2019. Schedule risk puts the length of the slide at a maximum of 6 months (June 2020). SLS slips are constant and always moving to the right. I have zero faith in the 2022 date for EM-2. EM-2 is currently predicated on the managed date for EM-1 for launch in June of 2022. IF EM-1 takes the maximum expected slide and they are unable to compress the 'stick' between the two launches EM-2 launches just before Christmas of 2022. Between now and EM-2 we're looking at about $15 to $18 billion to be spent on SLS/Orion (depending on when it actually flies). That does not include any money spent before today, only money we're going to spend. It's absurd how much we're spending on a vehicle that will almost certainly be obsolete before it starts flying "routinely" at a cadence of at most 2 flights per year at a cost to the US taxpayer of well over $1 billion a flight. NASA's current long range plan puts the first Mars mission (with no landing) out in like 2033. I think it's pretty obvious that even with the expected schedule slides Musk will beat them there. -- "The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man." --George Bernard Shaw |
#44
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BFR early next year.
In article ,
says... On 2018-03-17 02:59, Fred J. McCall wrote: What are you gibbering about now? Enterprise was built in another era. No CAD/CAM and no experience in building a flying rocket. Irrelevant. The A-12, SR-71 Blackbird, X-15, XB-70, and a host of other aircraft and rocket powered winged vehicles were designed before CAD/CAM. You don't seem to have a point here. CAD isn't a panacea or silver bullet. It's a design tool, nothing more. CAM is the same. Very skilled machinists can do almost everything that CAM can do. Again, it's a manufacturing tool, nothing more. Enterprise was needed not only use to test gliding/landing but also to develop/test mounting on the full stack, as well as firing SRBs to measure vibration. The knowledge gained from it resulted in a production design sufficiently different that it wasn't worth retrofitting Enterprise. You're misrepresenting the facts here. The fact was that it was going to be more work to dismantle Enterprise and refit it than to build upon STA-99 which was nothing more than structure anyway (structural test articles are like that you know). Plus they had not yet gained the sensor data from flying Columbia to orbit and back. That gave them the information they needed to lighten the structure, not Enterprise's relatively mild glide landings. Columbia's data covered launch (including being shaken by the SRBs), max-Q, and reentry. Enterprise only provided subsonic flight data and landing data. BFS, on the other hand tests a fully functioning rocket capable of taking off and landing. Engines, tanks, software, aerodynamic controls/paddles, landing gear ad its deployment using real actuators (Enterprise used explosive bolts) etc. (not sure if it will have side thrusters for attitude control) Sure, it will lack a payload, crew compartment, ECLSS etc. But from the rocket point of view, it should be a fairly functional system. Furthermore, it is an evolution from experience gained from Falcon 9 whereas the Shuttle was truly the "undiscovered Country" since it was not an evolution from Apollo systems/designs. You must be completely forgetting the myriad of research vehicles between the USAF and NASA which were targeted at eventually making an operational spacecraft that could reenter and land on a runway. Several of these designs flew on top of launch vehicles and performed unmanned reentries. There are a few sitting in the USAF Museum in Dayton Ohio. Check their website. They'll have pictures and summaries of each online. You might learn something. The fact is that the space shuttle orbiter design was *not* created in a vacuum. You don't need the vacuum engines to lift off and land. You do need some if you're planning on going clear to space, but even then you probably don't need all of them until you start flying heavy cargos. Montréal got some new Métros about 2 years ago. Previous generation was designed in early 1970s. Alstom got the contract for the bogies/motors and went with a fancy pneumatic suspension as well as the tires for our métro. All built to fit the existing tunnel dimensions, platform height and loading gauge. BUT... during testing, the STM (transit company)discobered that if the tires blew AND the penumatic suspension lost pressure, a car could sway enough to rub against tunnel walls in some areas. (previous generation had spring suspension, so failure of suspension had not been something they worried about when defining the specs of the vehicle). WTF does any of this have to do with a VTVL TSTO? They may very well make the first BDF launch without vacuum engines. But this would not validate things very well. If the goal is to validate the design, and if the vacuum engines are Raptor engines with different bells, they may want to load them up. (or peruaps load early production Raptors with vacuum bells to occupy the space and weigfht. Maybe. Or they could test incrementally (like they always seem to do). Grasshopper certainly wasn't equipped with 9 Merlin engines. It wasn't even equipped with the final design of the landing legs. It didn't need either of them to fly and gather the data they needed. I'm sure the SpaceX engineers understand the trades with the first BFR/BFS stages better than we do. Prior to launch, they can then test that interaction between engine bells is within specs in all failure modes, and that a vacuum bell stuck in the worng orientation won't prevent a launch engine from gaving full gimball movement. (expecially needed for landing when rapid changes are needed). Not sure what you're yammering on about. If you don't need the heat shield then you don't need the vacuum engines. The heat shield is just fancy outside skin. Vacuum engines are mounted amongst launch/landing engines so ensuring the whole engine "pod" works even when half the engines are not fired is important. You don't have anything to back up this hand waving. Also, assuming BFS 1,0 does not result in fireworks, the work done to assemble a more complete vehicle would be of use for its second flight. (and one would have to do risk management to decide wether to mount good vacuum engines, or duds from early production but with proper vaccum bells.) SpaceX will no doubt do many small hops with version 1 of the vehicle. They're not going to do one small hop and declare they're ready to go to orbit. That's not how they work. Build a little, test a little, fly a little. Iterative. That's how they work. Version 2 won't fly until they've gathered all the data they need from version 1. So, version 1 may or may not be equipped with a full compliment of Raptor engines, a combination of real and dummy engines. That's up to the SpaceX engineers to decide. And depending on software, I could see a case for needing the vaccum engines in the event that sea leavel engines fail during landing. (depending on where in teh cluster those engines are located). No, you can't fire the vacuum engines and use them for landing. You'd get flow separation and the bells might very well destroy themselves, which wouldn't make for a very safe landing when your engines are literally falling apart. Besides, that's why there will be three Raptor engines in the center, for redundancy during landing. So just because the grasshoper tests doesn't require vacuum engines on paper doesn't mean that they won't want to have them on for the test because integrating as many compotents as possible is a better test. We'll see, but I seriously doubt that they'd bolt a bunch of engines that aren't needed on the test vehicle. Those engines aren't free you know. Why risk millions of dollars in engines you don't need on a test flight? Makes no sense unless you really do need them, which they don't. I don't know why you're so wrapped around the axle about the damned tank, since we all know that's done. Enterprise didn't have fully functioning tanks. Didn't have its real fuel cells and O2/H2 tanks, didn't have hypergolics. BFS will have fully functional tanks. So it is far ahead in terms of moving from "idea" to "product" then Enterprise was. All those systems you mention on Enterprise weren't needed for subsonic flight of the vehicle. Not including them on Enterprise made sense. If the first BFR/BFS test vehicle is only making "short hops" it won't need vacuum engines. Not including real vacuum engines on the test vehicle might make sense in the very same way. And this is why advancing first flight is significant because first flight really needs to have a lot of the final systems finalized. Depends on how high the "hop" is. If it's not high enough to need vacuum engines, why include them in the test? No, it was designed as a test article, which is not the same thing. Test article for something that had never been done before. And with many changes made as it was being developped (liquid fltyback boosters abandonned etc). This is gobbledygook. The configuration of the STS was finalized long before any metal was bent. That included the SRBs and drop tank (ET). The size of the orbiter's payload bay and payload mass was set as well. While the payload of BFS (aka: crew compartment for 100 passengers) is likely going to change a lot from early concepts, the propulsion/tanks portion as lower structures are likely to be fairly close to final designs with tweaks over time. (as has happened with Falcon 9). Untrue. Block 5 Falcon 9 has many significant differences when compared to Falcon 9 V 1.0. Not all are visible from the outside but things like the height of the vehicle, changing the engine configuration from a square to the "octoweb", and the inclusion of landing legs and grid fins are externally visible. https://en.wikipedia.org/wiki/Falcon_(rocket_family) Most important is the sheer size of the vehicle and engine improvements. Improvements to Merlin allowed tank stretches and overall performance improvements over V 1.0. Part of the reason Falcon Heavy kept getting delayed is that Falcon 9 kept getting higher payload capacity and could therefore launch some payloads originally intended for Falcon Heavy. Horse****. They didn't design the thing using bearskins and stone axes, you know. When you look at the history of the shuttle, there was a lot that wasn't predicted while it was being designed. Understanvbly so since this was something that had never been done before. Re-usable design, totally different stack at launch pad, totally different landing, HUGE crew cabin from before, new materials, new heat shield etc etc. With each delay, each incident and the 2 losses, failure modes that had not been predicted during design crept up. This is nonsense. As I said before, the overall configuration was fixed long before metal was bent. You really need to read this book: Space Shuttle: The History of the National Space Transportation System The First 100 Missions Hardcover - May 11, 2001 by Dennis R. Jenkins (Author) https://www.amazon.com/Space-Shuttle...ransportation- Missions/dp/0963397451 In the case of BFR/BFS, Musk is scaling the experience of Falcon 9 as a core, and adding new stuff like heat shield, and re-usable second stage (BFS). landing and re-usability have already been tested. (and Falcon 9 learned from the experience of the difficult re-usability of Shuttle). So first flight of BFS will incorporate systems/experience that will make it a far more complete ship compared to eventual production than Enterprise was compared to the production Shuttles. That's because Enterprise was only the orbiter. The SRBs and the ET made up 95% of the launch part of the system. The orbiter only contained the flight computers, SSMEs, and the OMS pods. Everything else needed for launch dropped off before the shuttle got to orbit. BFR/BFS isn't going to dispose of any parts. It's quite different than the space shuttle in that regard. So some of the shuttle experience simply won't apply because it's just not the same. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#45
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BFR early next year.
In article ,
says... On 2018-03-17 09:33, Jeff Findley wrote: If it is able to propulsively land on Earth, doesn't that more or less imply ability to land on Mars? Block 1 might not be able to be refueled, so it couldn't get to Mars in the first place. I was asking in terms of design/concept, not about early production models. Huh? If the vehicle built is missing key components needed for a Mars mission, it can't really be said to be capable of such "in concept". Earth has stronger gravity, but also denser atmosphere. So if you have enough thrust to decererate and land on Earth, would this imply that you have enough thrust to land on Mars? (less gravity, but also much less atmosphere to slow you down) Yes, you need less thrust to land on Mars. In a "Pan Am flight 006 to Mars and back, would the mass of the vehicle making the drop from space and land to surface be roughly the same ? Or would landing at one planet require much more fuel? You'd need a lot more fuel and oxidizer to land on Mars since Mars atmosphere is so thin you won't get anywhere near as much aerodynamic braking as you get on earth. So shedding velocity will require a much longer burn from the engines than on earth (where the engines only need to perform a relatively short landing burn). So far, Falcon 9 stage 1 landed mostly enpty without payload and with just enough fuel to land. But BFS will land with full payload of people and 6 months worth of garbage. So onlike Falcon 9 stage 1, BFS is likely to require a far greater percentage of its engines to land. Right ? (hence question of whether the number of engines needed is dictated by the eventual landing with 100 passengers on Earth or on Mars). https://ourplnt.com/making-life-multiplanetary/bfs/ BFS will have three sea level engines for landing. But the extras are mostly there for redundancy. Depending on the payload, I'd think one would be sufficient in most cases, even on earth. Raptor will have about 400,000 lbf thrust at landing. Dry mass of BFS is reported to be about 200,000 lbs. A "typical" payload at landing is reported to be 110,000 lbs. So one Raptor is all that's needed for a "typical" landing. Of course, these numbers might change over time with block upgrades, just as they did for Falcon 9. Jeff -- All opinions posted by me on Usenet News are mine, and mine alone. These posts do not reflect the opinions of my family, friends, employer, or any organization that I am a member of. |
#46
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BFR early next year.
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#47
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BFR early next year.
Le Mar/18/2018 Ã* 9:56 AM, Jeff Findley a écritÂ*:
In article , says... On 2018-03-17 09:33, Jeff Findley wrote: If it is able to propulsively land on Earth, doesn't that more or less imply ability to land on Mars? Block 1 might not be able to be refueled, so it couldn't get to Mars in the first place. I was asking in terms of design/concept, not about early production models. Huh? If the vehicle built is missing key components needed for a Mars mission, it can't really be said to be capable of such "in concept". Earth has stronger gravity, but also denser atmosphere. So if you have enough thrust to decererate and land on Earth, would this imply that you have enough thrust to land on Mars? (less gravity, but also much less atmosphere to slow you down) Yes, you need less thrust to land on Mars. In a "Pan Am flight 006 to Mars and back, would the mass of the vehicle making the drop from space and land to surface be roughly the same ? Or would landing at one planet require much more fuel? You'd need a lot more fuel and oxidizer to land on Mars since Mars atmosphere is so thin you won't get anywhere near as much aerodynamic braking as you get on earth. So shedding velocity will require a much longer burn from the engines than on earth (where the engines only need to perform a relatively short landing burn). So far, Falcon 9 stage 1 landed mostly enpty without payload and with just enough fuel to land. But BFS will land with full payload of people and 6 months worth of garbage. So onlike Falcon 9 stage 1, BFS is likely to require a far greater percentage of its engines to land. Right ? (hence question of whether the number of engines needed is dictated by the eventual landing with 100 passengers on Earth or on Mars). https://ourplnt.com/making-life-multiplanetary/bfs/ BFS will have three sea level engines for landing. But the extras are mostly there for redundancy. Depending on the payload, I'd think one would be sufficient in most cases, even on earth. Raptor will have about 400,000 lbf thrust at landing. Dry mass of BFS is reported to be about 200,000 lbs. A "typical" payload at landing is reported to be 110,000 lbs. So one Raptor is all that's needed for a "typical" landing. According to the numbers you give one Raptor engine isn't enough unless you have a lot of fuel for landing. One Raptor has enough thrust for about 1.3 g. The first g only compensates for gravitation so you have 0.3 g of deceleration. If you are coming in at say 100 m/s, you would need a 34 second burn. That isn't a problem, but it isn't the way the Falcon rockets land. If you have three Raptor engines, that gives you 3.9 g - 1 g for gravitation = 2.9 g of deceleration. So now instead of a 34 second burn you now need a 3.5 second burn. Three engines for 3.5 seconds burn less than one third what one engine burns in 34 seconds. So again, landing with one engine isn't really a problem but you need to keep more fuel for landing if you want to do that. Alain Fournier |
#48
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BFR early next year.
JF Mezei wrote on Sun, 18 Mar 2018
07:19:06 -0400: On 2018-03-17 02:59, Fred J. McCall wrote: What are you gibbering about now? Enterprise was built in another era. No CAD/CAM and no experience in building a flying rocket. False. And I note you 'cleverly' removed your original comments. Enterprise was needed not only use to test gliding/landing but also to develop/test mounting on the full stack, as well as firing SRBs to measure vibration. False. Enterprise was never mated to live SRBs The knowledge gained from it resulted in a production design sufficiently different that it wasn't worth retrofitting Enterprise. False. BFS, on the other hand tests a fully functioning rocket capable of taking off and landing. Engines, tanks, software, aerodynamic controls/paddles, landing gear ad its deployment using real actuators (Enterprise used explosive bolts) etc. (not sure if it will have side thrusters for attitude control) Again, you only need the three sea level engines for all of that. PAY ATTENTION!!!!!! Sure, it will lack a payload, crew compartment, ECLSS etc. But from the rocket point of view, it should be a fairly functional system. Why would it lack most of those things? If you're going to test handling and flight, you need the moment arms and CGs to be as close as possible to the intended final article. You can't add all that stuff as an afterthought. It's part of dry structure. You can add engines and heat shield later, since those things are intended to be removable so they can be refurbished/replaced. Furthermore, it is an evolution from experience gained from Falcon 9 whereas the Shuttle was truly the "undiscovered Country" since it was not an evolution from Apollo systems/designs. Well, not so much. BFR Spaceship is a totally new kind of thing using totally different engines. You don't need the vacuum engines to lift off and land. You do need some if you're planning on going clear to space, but even then you probably don't need all of them until you start flying heavy cargos. Montréal got some new Métros about 2 years ago. Previous generation was designed in early 1970s. Alstom got the contract for the bogies/motors and went with a fancy pneumatic suspension as well as the tires for our métro. All built to fit the existing tunnel dimensions, platform height and loading gauge. BUT... during testing, the STM (transit company)discobered that if the tires blew AND the penumatic suspension lost pressure, a car could sway enough to rub against tunnel walls in some areas. (previous generation had spring suspension, so failure of suspension had not been something they worried about when defining the specs of the vehicle). BFR Spaceship isn't a subway train. They may very well make the first BDF launch without vacuum engines. But this would not validate things very well. If the goal is to validate the design, and if the vacuum engines are Raptor engines with different bells, they may want to load them up. (or peruaps load early production Raptors with vacuum bells to occupy the space and weigfht. Why? Prior to launch, they can then test that interaction between engine bells is within specs in all failure modes, and that a vacuum bell stuck in the worng orientation won't prevent a launch engine from gaving full gimball movement. (expecially needed for landing when rapid changes are needed). Mayfly, engineers don't just build **** and hope it works. Yes, some things only come out with full up testing but this is not one of those things. If you don't need the heat shield then you don't need the vacuum engines. The heat shield is just fancy outside skin. Vacuum engines are mounted amongst launch/landing engines so ensuring the whole engine "pod" works even when half the engines are not fired is important. Do you have any conception at all of how engineering works? Also, assuming BFS 1,0 does not result in fireworks, the work done to assemble a more complete vehicle would be of use for its second flight. (and one would have to do risk management to decide wether to mount good vacuum engines, or duds from early production but with proper vaccum bells.) You think they're going to have a lot of 'dud' engines, do you? And depending on software, I could see a case for needing the vaccum engines in the event that sea leavel engines fail during landing. (depending on where in teh cluster those engines are located). There are 3 sea level engines. You need ONE in order to land. So just because the grasshoper tests doesn't require vacuum engines on paper doesn't mean that they won't want to have them on for the test because integrating as many compotents as possible is a better test. So you think you know more than Elon Musk about BFR Spaceship, do you? The things SANE engineers would leave off the vehicle are things that are intended to be easily removable and replaceable. That's things like engines and heat shield. It is certainly NOT major structural components. I don't know why you're so wrapped around the axle about the damned tank, since we all know that's done. Enterprise didn't have fully functioning tanks. Didn't have its real fuel cells and O2/H2 tanks, didn't have hypergolics. BFS will have fully functional tanks. So it is far ahead in terms of moving from "idea" to "product" then Enterprise was. I repeat - I don't know why you're so wrapped around the axle about the damned tank, since we all know that's done. You do love removing your original remarks, don't you? And this is why advancing first flight is significant because first flight really needs to have a lot of the final systems finalized. 'Advancing first flight'? What the **** are you talking about now? No, it was designed as a test article, which is not the same thing. Test article for something that had never been done before. And with many changes made as it was being developped (liquid fltyback boosters abandonned etc). Again you remove your original comment, WHERE YOU WERE ONCE AGAIN WRONG. Then you argue with being told you were wrong. While the payload of BFS (aka: crew compartment for 100 passengers) is likely going to change a lot from early concepts, the propulsion/tanks portion as lower structures are likely to be fairly close to final designs with tweaks over time. (as has happened with Falcon 9). Why would it 'change a lot'? Static dry structure is the EASY part of the vehicle. elide remaining nonsense -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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BFR early next year.
JF Mezei wrote on Sun, 18 Mar 2018
07:29:26 -0400: On 2018-03-17 09:33, Jeff Findley wrote: If it is able to propulsively land on Earth, doesn't that more or less imply ability to land on Mars? Block 1 might not be able to be refueled, so it couldn't get to Mars in the first place. I was asking in terms of design/concept, not about early production models. Earth has stronger gravity, but also denser atmosphere. So if you have enough thrust to decererate and land on Earth, would this imply that you have enough thrust to land on Mars? (less gravity, but also much less atmosphere to slow you down) Asked and answered. Let me make it clear for you. *********************** N O *********************** Get it now? In a "Pan Am flight 006 to Mars and back, would the mass of the vehicle making the drop from space and land to surface be roughly the same ? Or would landing at one planet require much more fuel? So far, Falcon 9 stage 1 landed mostly enpty without payload and with just enough fuel to land. But BFS will land with full payload of people and 6 months worth of garbage. So onlike Falcon 9 stage 1, BFS is likely to require a far greater percentage of its engines to land. Right ? (hence question of whether the number of engines needed is dictated by the eventual landing with 100 passengers on Earth or on Mars). The most important difference is that you probably use vacuum engines to land on Mars, given the lack of atmospheric pressure. -- "Some people get lost in thought because it's such unfamiliar territory." --G. Behn |
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BFR early next year.
JF Mezei wrote on Sun, 18 Mar 2018
07:36:58 -0400: On 2018-03-17 10:48, Fred J. McCall wrote: NASA's current long range plan puts the first Mars mission (with no landing) out in like 2033. I think it's pretty obvious that even with the expected schedule slides Musk will beat them there. When must NASA start to get funding to develop whatever will travel between Earth and Mars and back? They can probably just buy a B330 module. Eventually, NASA will have to stop pretending that Orion is big enough to carry people to and from Mars on a 1 year mission, and perhaps have to fess up that it needs to develop a Mars lander and take-off vehicle if it intends to put humans on Mars surace and bring them back. No plans to land through 2033. -- "Ignorance is preferable to error, and he is less remote from the truth who believes nothing than he who believes what is wrong." -- Thomas Jefferson |
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