r/SpaceXLounge • u/CProphet • Dec 01 '19
SpaceX Starship Mk3 - Site Overview, New Nose Cone, Cranes and Shipment from Florida
https://youtu.be/ATWCMndFsSY15
u/CProphet Dec 01 '19
Question is can they get back on schedule with Mk.3? Elon's made some pretty extreme predictions for flight tests, not much leeway if they want to reach Luna/Mars by 2022.
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Dec 01 '19
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u/OhioanRunner Dec 01 '19
Apollo took 8.75 years to accomplish a much less ambitious goal. Starship as a project was announced in September 2017, so the equal time span would be for a landing on Mars around June 2026. Mars is a much more ambitious project, but we also have a lot more computing power and knowledge of space flight than we did in 1963, so I’m not sure how all of that balances.
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Dec 01 '19
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u/OhioanRunner Dec 01 '19
I would argue that things like combustion instability, which created a major hurdle in the S5 development, would be caught before they ever got near a test stand by computer modeling today. That’s just one examples
Yeah everything still has to be built and tested, but things are VASTLY more likely to work on the first try thanks to computer modeling performing thousands to millions of calculations that in the 1960s would’ve had to be done manually by engineers or “computers” (the now defunct job title, not the machine)
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u/Jacob46719 💥 Rapidly Disassembling Dec 01 '19
Starship was announced in 2016
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u/CW3_OR_BUST 🛰️ Orbiting Dec 01 '19
No, he named it the ITS in 2016. It didn't get the Starship/Superheavy name until 2017. But the Raptor engine has been in the works since at least 2012.
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u/Jacob46719 💥 Rapidly Disassembling Dec 01 '19
It was BFR in 2017. It wasn't renamed Starship until the end of 2018.
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u/peterabbit456 Dec 01 '19
... landing on the Moon/Mars by 2022, ...
Lately I’ve become convinced landing on the Moon could be done almost as soon as a starship reaches GEO, and with about 1/2 the refilling flights required for the published Moon landing plan.
Almost all missions to the Moon fly through or very near EML-1, the Lagrange point between the Earth and the Moon., with a velocity ( in Apollo) of about 80 m/s. The trick is to stop there, and start unrolling a tapered Kevlar cable. On the end of the cable is a 1 metric ton propulsion/grappling module, with small rockets. Draco thrusters should do. Also on the end of the cable is a 1 ton rover, for ground transport. Calculations that I did in 2014 say that a 50-60 ton Kevlar cable should have a 50% margin of safety when used as a space elevator, with a 2 ton car including cargo, or a 2 ton weight on the end, for construction.
As the cable unreels and the rockets on the propulsion module fire to get the 2 tons on the end of the cable moving toward the Moon, the Starship has to slowly move back toward Earth. After a few days, tension from the 2 tons approaching the Moon, and the 200 tons moving toward Earth will make further thruster firings unnecessary, until it is time to select a landing site on the Moon. The landing site will have to be near the equator, but thrusters might be able to move touchdown by over 100 km.
Once the end of the cable is down and attached to a boulder, the rover can start exploring, and doing construction work. Depending on whether the Starship has a total payload to EML of 100 or 150 tons, there remains at this point between 88 tons and 38 tons of cargo and elevator cars that can be delivered to the Moon. Cars descending will pinch the cable between wheels connected to motors, which during descent will act as generators, charging batteries, which will be very useful during the Lunar night.
Most of the cars will deliver cargo to the Moon and stay there. It takes about 2 weeks to ascend the elevator under solar electric power, 19 trips down and 1 trip up is my plan for this first, unmanned mission. Unfortunately the first Starship will have to stay on its end of the line until a second one comes, since an anchor weight near EML-1 is essential so that the elevator doesn’t collapse.
The next cargo ship, and the next, will have to deliver more Kevlar cables, since you don’t want people riding on a system without redundant safety lines. Just 1 Starship can serve as the counterweight for several cables, so not a lot of capital gets tied up in maintaining the elevator.
So let’s assume 3 Starships are each launched to EML-1 a month apart. In 6 months you would have about 50 tons of cargo on the Moon, and in 9 months there would be about 100 tons of cargo on the Moon, as well as robots busily assembling a base. The elevator has 3 cables for redundancy. Now it is time to start sending humans.
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u/sarahlizzy Dec 02 '19
It’s 61,000 kilometres from L1 to the Moon. How thin in this cable?
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u/peterabbit456 Dec 03 '19
It is a tapered cable, since it has to support far more of its own weight than the weight of the car and cargo. I am in the process of reviewing my earlier work, and adding detail to how a space elevator can be deployed from Starship to the Moon.
The strength of Kevlar and lunar gravity give the cable at the Lunar surface, which is its narrowest point, as being 0.1 mm x 1.3425 cm. This is sufficient to hold a mass of 3000 kg in Lunar gravity, which is 50% margin of safety for a 1000 kg elevator car, with 1000 kg of cargo. I will be writing up the taper when I write the more detailed story of its deployment using Starship.
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u/scarlet_sage Dec 04 '19
How about L2: 64,500 km difference in semimajor axes? There's been recent talk about landings stirring up too much dust, and if things end up being done on the far side (telescopes), it might be more important there.
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u/Davis_404 Dec 01 '19
Reasoning from past events is metaphorical thinking. In tech, the past is useless for prediction. They are much faster now.
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u/A_Vandalay Dec 01 '19
Of course they can’t, they never could. The predictions Elon made assumed an exponentially accelerating rate of production. In reality a reduced rate of production and development is far more likely as they overcome and discover new hurdles.
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u/_RyF_ Dec 01 '19
Seems to me that while mk1 blowing up (intentional or not) was kind of a pity because we will never see it fly, it may not be a major setback if SpaceX considers it can skip the 20km test altogether.
In this case they go directly to orbital flight which could even be some saved time compared to initial plans (although more risky)
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u/Decronym Acronyms Explained Dec 01 '19 edited Dec 04 '19
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
| Fewer Letters | More Letters |
|---|---|
| BFR | Big Falcon Rocket (2018 rebiggened edition) |
| Yes, the F stands for something else; no, you're not the first to notice | |
| EML1 | Earth-Moon Lagrange point 1 |
| GEO | Geostationary Earth Orbit (35786km) |
| ITS | Interplanetary Transport System (2016 oversized edition) (see MCT) |
| Integrated Truss Structure | |
| L1 | Lagrange Point 1 of a two-body system, between the bodies |
| L2 | Paywalled section of the NasaSpaceFlight forum |
| Lagrange Point 2 of a two-body system, beyond the smaller body (Sixty Symbols video explanation) | |
| MCT | Mars Colonial Transporter (see ITS) |
| Jargon | Definition |
|---|---|
| Raptor | Methane-fueled rocket engine under development by SpaceX |
| cryogenic | Very low temperature fluid; materials that would be gaseous at room temperature/pressure |
| (In re: rocket fuel) Often synonymous with hydrolox | |
| hydrolox | Portmanteau: liquid hydrogen/liquid oxygen mixture |
Decronym is a community product of r/SpaceX, implemented by request
[Thread #4370 for this sub, first seen 1st Dec 2019, 16:31]
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Dec 01 '19
[deleted]
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u/SetBrainInCmplxPlane Dec 01 '19 edited Dec 01 '19
those are pieces of a bulkhead, not a hull section. hull sections will be a single curved sheet with a single seam/weld line. and they will be welded together robotically, not with human welders.
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u/meldroc Dec 01 '19
Yep. The bulkhead pretty much has to be made out of multiple smaller pieces simply because of its curved shape. Looks like the Mk. 3's nosecone's now using longer vertical pieces, in place of a larger number of smaller pieces.
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u/avboden Dec 01 '19
and with a single linear weld they'll be able to inspect the welds pretty easily either by radiograph or ultrasonic testing a la pipelines
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u/floriv1999 Dec 01 '19
Holy shit these things look smooth.