Glad that other folks elsewhere can view those links. BFR looks like this: It is not a trivial matter to make a very large mixer/ignitor just upstream from nozzle (see Saturn V). Musk has chosen smaller and more of them. That presents different challenges. All must be synchronized in thrust, and if any one lags, some computer needs to compensate. So much computer. We are perhaps at the point where computers outdo individual thrust-chamber bigness. And yet if this is all we can muster to accelerate large items out of earth's gravity well, we remain rather lightweight in space going. Perhaps 2nd half of this century will provide better technology. If our limits are ~100 tons 'out there', then humans are pretty much a local species.
Sorry about the YouTube links. This may help: The bottom of Falcon heavy is shown with three, Falcon 9 boosters. The Big F*cking Rocket is distinctly different. I'll see if I can find a PDF or better text summary of Elon's presentation. There are more details about the Falcon Heavy: Falcon Heavy | SpaceX I haven't audited this transcript: Part 1 of 4: Transcript – Elon Musk, IAC 2017, “Making Life Multiplanetary” sol3tosol4 September 29, 2017 Based on the copy of the video on the SpaceX website here(length 43:47). Any errors are mine. Lightly edited – some repetition and extraneous remarks removed, some descriptions of slides added for reference, comments are in Part 4 01:45 – Elon Musk walks on stage [applause] I’m going to talk more about what it takes to become a multi-planet species. And just a brief refresher on why this is important: I think fundamentally the future is vastly more exciting and interesting if we’re a space-faring civilization and a multi-planet species than if we’re not. You want to be inspired by things. You want to wake up in the morning and think “the future’s going to be great”. And that’s what being a space-faring civilization is all about. It’s about believing in the future and thinking that the future will be better than the past. And I can’t think of anything more exciting than going out there and being among the stars. That’s why. 02:40 – So let me go into more detail on becoming a multi-planet species. This is the updated design for the – well, we’re sort of searching for the right name, but the code name, at least, is BFR. Probably the most important thing that I want to convey in this presentation is that I think we have figured out how to pay for it. This is very important. In last year’s presentation, we were really searching for the right way…how to we pay for this thing? We went through various ideas, Kickstarter, collecting underpants [South Park reference], these didn’t pan out. But now we think we’ve got a way to do it, which is to have a smaller vehicle – it’s still pretty big, one that can do everything that’s needed in the greater Earth orbit activity. So essentially we want to make our current vehicles redundant. We want to have one system, one booster and ship, that replaces Falcon 9, Falcon Heavy, and Dragon. If we can do that, then all the resources that are used for Falcon 9, Heavy, and Dragon can be applied to this system. That’s really fundamental. 04:37 – What progress have we made in this direction? Last time you saw the giant tank – that’s actually a 12-meter tank [slide showing the carbon fiber tank; Pressure tested to 2.3 atmospheres; New carbon fiber matrix; Volume 1000 m3; Holds 1200 tons of liquid oxygen]. It’s 1000 cubic meters of volume inside. That’s actually more pressurized volume than an A380, to put that into perspective. We developed a new carbon fiber matrix that’s much stronger and more capable at cryo than anything before, and it holds 1200 tons of liquid oxygen. 05:12 – So we tested it [slide – video showing carbon tank under test – white with frost – eventually ruptures and shoots into the air] – we successfully tested it up to its design pressure, and then went a little further. So we wanted to see where it would break, and we found out. It shot about 300 feet into the air and landed in the ocean – we fished it out. We’ve now got a pretty good sense of what it takes to create a huge carbon fiber tank that can hold cryogenic liquid – that’s actually extremely important for making a light spaceship. 05:53 – The next key element is on the engine side – we have to have an extremely efficient engine. The Raptor engine will be the highest thrust to weight ratio of any kind of engine ever made. We already have now 1200 seconds of firing across 42 main engine tests. We’ve fired it for 100 seconds – it could fire much longer than 100 seconds, that’s just the size of the test tanks. The duration of the firing you see [in this video] is 40 seconds which is the length of the firing for landing on Mars. The test engine currently operates at 200 atmospheres (200 bar).The flight engine will be at 250 bar, and we believe that over time we can get that to a little over 300 bar. 06:50 – The next key element is propulsive landing. In order to land on the moon (no atmosphere) or on Mars (atmosphere is too thin to land with a wing), you really have to get propulsive landing perfect. So that’s what we’ve been practicing with Falcon 9 [video of landings]… We now have 16 successful landings in a row [error – it’s 16 total, 12 in a row] – and that’s really without any redundancy. So Falcon 9 – the final landing is always done with a single engine, whereas BFR will always have multi-engine-out capability. So if you can get to a very high reliability with even a single engine, and then you can land with either of two engines, I think we can get to a landing reliability that is on par with the safest commercial airliners. So you can essentially count on the landing… 08:31 – And it can also land with very high precision. In fact, we believe the precision at this point is good enough for propulsive landing that we do not need legs for the next version. It will land with so much precision that it will land back on its launch mounts. 08:53 – The launch rate is also increasing exponentially [slide: 2012 – 2; 2013 – 3; 2014 6; 2015 – 7; 2016 – 8; 2017 – 13 + 7 projected = 20; 2018 – 30 projected]. Particularly when you take refilling on orbit into account, and taking the idea of establishing a self-sustaining base on Mars or the moon or elsewhere seriously, you need thousands of ships, and tens of thousands of tanking / refilling operations, which means that you need many launches per day… [At present] approximately 60 orbital launches occur per year. Which means that if SpaceX does do something like 30 launches next year, it’ll be approximately half of all orbital launches that occur on Earth. 10:10 – The next thing – a key technology is automated rendezvous and docking. In order to retank or refill the spaceship in orbit, you have to be able to rendezvous and dock with the spaceship with very high precision, and transfer propellant. That’s one of the things that we’ve perfected with Dragon. Dragon [2] will do an automated rendezvous and docking without any pilot control, to the Space Station. Dragon 1 currently uses the Canadarm for final placement onto the Space Station. Dragon 2, which launches next year, will not need to use the Canadarm. Dragon 2 will directly dock with the Space Station, and it can do so with zero human intervention – just press “Go”, and it will dock. Dragon has also allowed us to perfect heat shield technology. When you enter at high velocity, you melt almost anything… so you have to have a sophisticated heat shield technology that can withstand unbelievably high temperatures. And that’s what we’ve been perfecting with Dragon. And also a key part of any planet colonizing system. 11:50 – So Falcon 1, this is where we started out… [slide: 1.7m diameter, 21.3m high]. We started with just a few people, who really didn’t know how to make rockets. The reason I ended up being the chief engineer or chief designer was not because I wanted to, it’s because I couldn’t hire anyone… I messed up the first 3 launches, the first 3 launches failed. Fortunately the fourth launch – that was the last money that we had – worked, or that would have been it for SpaceX. But fate liked us that day. Just think – today is the ninth anniversary of that launch [applause]. I didn’t realize that until I was told that just earlier today. This is a pretty emotional day, actually. Falcon 1 was quite a small rocket – …trying to figure out what is the smallest useful payload that we could get to orbit – something around half a ton… 13:50 – It’s really quite small compared to Falcon 9 [slide: 3.7m by 70m, 15 tons to orbit with partial reuse]. Falcon 9 is ~30 times more payload than Falcon 1. And Falcon 9 has reuse of the primary booster, which is the most expensive part of the rocket, and hopefully soon reuse of the fairing. We think we can probably get to somewhere between 70 and 80 percent reusability with the Falcon 9 system. 14:35 – And hopefully towards the end of this year we’ll be launching Falcon Heavy. FH ended up being a much more complex program than we thought [slide: FH 12m by 70m, 30 tons to orbit with partial reuse]. It sounds easy, 2 stages of Falcon 9 strapped on as boosters. It’s actually not – we had to redesign almost everything except the upper stage in order to take the increased loads. So FH ended up being much more a new vehicle than we realized. So it took us a lot longer to get it done, but the boosters have all now been tested, and they’re on their way to Cape Canaveral. 15:30 – And we are now beginning serious development of BFR. So you can see the payload difference is quite dramatic [slide: 9m by 106m, 150 tons to orbit with full reuse]. BFR in fully reusable configuration, without any orbital refueling, we expect to have a payload capability of 150 tons to LEO… Where this really makes a tremendous difference is in the cost, which I’ll come to in some of the later slides. 16:22 – [slide: Falcon 9 ~22 tons to LEO expendable, FH ~63 tons to LEO expendable, BFR ~250 tons to LEO expendable] 16:28 – [slide: BFR including booster, shown horizontal, with a human to scale, “31 Raptor engines produce liftoff thrust of 5400 tons, lifting total vehicle mass of 4400 tons”] It’s really quite a big vehicle. The main body diameter is about 9 meters or 30 feet. The booster is lifted by 31 Raptor engines that produce a thrust of about 5400 tons, lifting a 4400 ton vehicle straight up. This link may also help. I see the "transcript" looks to be some "media". Mars | SpaceX Bob Wilson
Wow. 27 sets of pumps / chambers / nozzles. For a human rated booster, that certainly raises the per-component reliability requirement. At least at lift-off. Though higher up, when they can (or must) start shutting down individual engines to limit g forces, the computer need not be limited to a fixed sequence and timing, but ought to gain considerable flexibility in which engines to shut down, and when. This should lead to greater fault tolerance.
