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Thread: SpaceX BFR/BFS SuperHeavy vehicles (space jogging?)

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    Moderator Dr Mordrid's Avatar
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    Default SpaceX BFR/BFS SuperHeavy vehicles (space jogging?)

    And here we go....

    The systems new name: Interplanetary Transport System

    Why a new name? Because it'll be capable of missions well beyond Mars; deltaV based candidates should include the asteroid belt (Ceres, Vesta etc.), Venus orbit, the Moon, and possibly Callisto - an outer moon of Jupiter the size of Mercury.

    Booster name during development was BFR: Big F'ing Rocket

    Spacecraft name during development was BFS: Big F'ing Spaceship

    Both are likely to get new names before or during Musk's speech.

    Earth to Mars: 100 tonnes of cargo

    Mars to Earth: 25 tonnes of cargo

    Passengers: up to 100

    The Raptor engine to power these monsters is on the test stand at McGregor Texas.

    YouTube Live Event: September 27, 2016

    1330 Central, 1430 Eastern, 1930 UT

    International Astronautical Council (IAC) 2016 in Guadalajara, Mexico

    Making Humans a Multiplanetary Species

    Scheduled for Sep 27, 2016

    SpaceX Founder, CEO, and Lead Designer Elon Musk will discuss the long-term technical challenges that need to be solved to support the creation of a permanent, self-sustaining human presence on Mars. The technical presentation will focus on potential architectures for sustaining humans on the Red Planet that industry, government and the scientific community can collaborate on in the years ahead.
    Last edited by Dr Mordrid; 20th September 2016 at 19:51.
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    Moderator Dr Mordrid's Avatar
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    YAY!!!! An engine designed for human interplanetary travel.

    Propellants: liquid methane and superchilled liquid oxygen (66° Kelvin)

    @elonmusk
    SpaceX Propulsion just achieved first firing of the Raptor Interplanetary Transport Engine https://t.co/vRleyJvBkx

    @elonmusk
    Production Raptor goal is specific impulse of 382 seconds and thrust of 3 MN (~310 metric tons) at 300 bar

    (note: 310t = 694,400 lbf)



    Mach diamonds

    Last edited by Dr Mordrid; 25th September 2016 at 22:48.
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    Moderator Dr Mordrid's Avatar
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    @elonmusk
    Chamber pressure is almost 3X Merlin, so engine is about the same size for a given area ratio

    @elonmusk
    @rocketrepreneur 382s is with a 150 area ratio vacuum (or Mars ambient pressure) nozzle. Will go over specs for both versions on Tues.
    Dr. Mordrid
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    Moderator Dr Mordrid's Avatar
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    @davidkyoon
    @elonmusk Sweet Jesus, that means you are pumping to 45-50 MPa... Surely this will be using multiple stage pumps?

    @elonmusk
    @davidkyoon yes

    @williamwinters
    @elonmusk @rocketrepreneur based on your other specs, is that like a ~14 foot diameter nozzle?

    (14 ft = ~4.2m)

    @elonmusk
    @williamwinters @rocketrepreneur pretty close
    Dr. Mordrid
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    Moderator Dr Mordrid's Avatar
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    SpaceX Interplanetar Transport System

    @elonmusk
    12m rocket booster diameter, 17m spaceship diameter, 122 m stack height



    Looks to be 42 engines, so about 28 million pounds of thrust.

    Dr. Mordrid
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    Dr. Mordrid
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    Elon Musk Reddit AMA

    My notes & quotes

    Early missions?

    EM: We are still far from figuring this out in detail, but the current plan is:

    Send Dragon scouting missions, initially just to make sure we know how to land without adding a crater and then to figure out the best way to get water for the CH4/O2 Sabatier Reaction.

    Heart of Gold spaceship flies to Mars loaded only with equipment to build the propellant plant.

    First crewed mission with equipment to build rudimentary base and complete the propellant plant.

    Try to double the number of flights with each Earth-Mars orbital rendezvous, which is every 26 months, until the city can grow by itself.

    Habitation construction?

    EM: Initially, glass panes with carbon fiber frames to build geodesic domes on the surface, plus a lot of miner/tunneling droids. With the latter, you can build out a huge amount of pressurized space for industrial operations and leave the glass domes for green living space.

    Materials challenges

    EM: It used to be developing a new metal alloy that is extremely resistant to oxidation for the hot oxygen-rich turbopump, which is operating at insane pressure to feed a 300 bar main chamber.

    Anything that can burn, will burn. We seem to have that under control, as the Raptor turbopump didn't show erosion in the test firings, but there is still room for optimization.

    Biggest question right now is sealing the carbon fiber tanks against cryo propellant with hot autogenous pressurization. The oxygen tank also has an oxidation risk problem as it is pressurized with pure, hot oxygen. Will almost certainly need to apply an inert layer of some kind. Hopefully, something that can be sprayed. If need be, will use thin sheets of invar welded together on the inside.

    What's been mastered?

    EM: Not sure that we've really mastered anything yet. Maybe starting engines...

    Sea level Raptor performance?

    EM: Approx 360 sec vacuum Isp and 290 metric tons of thrust. It had to be 42 for important scientific and fictional reasons! The dense packing is just to max out thrust to weight, but it would be cool if there was a virtual nozzle side effect.

    Can ITS booster hover?

    EM: A high acceleration landing is a lot more efficient, so there wouldn't be any hovering unless it encountered a problem or unexpected wind conditions. A rocket that lands slowly is wasting a lot of fuel.

    Max re-entry acceleration for booster?

    EM: Aiming for 20 g's. The spaceship would be limited to around 5 g's nominal, but able to take peak loads 2 to 3 times higher without breaking up. Booster would be nominal of 20 and maybe 30 to 40 without breaking up.

    ITS spaceship habitation layout?

    EM: I think we need a new name. ITS just isn't working. I'm using BFR and BFS for the rocket and spaceship, which is fine internally, but...

    Will aim to release details of the habitation section when we have actual live mockups. Maybe in a year or two.

    Configuration for large v small crew?

    EM: Probably just pack the pressurized space with cargo. Early missions will be heavily weighted towards cargo. First crewed mission would have about a dozen people, as the goal will be to build out and troubleshoot the propellant plant and Mars Base Alpha power system.

    Purpose of those spherical tanks?

    EM: The liquid oxygen transfer tube serves as the header tank for oxygen.

    Those are the header tanks that contain the landing propellant. They are separate in order to have greater insulation and minimize boil-off, avoid sloshing on entry and not have to press up the whole main tank.

    ITS booster v F9 landings, and coming F9 upgrade?

    EM: The big booster will have an easier time of things than Falcon, as the mass ratio of the stages is lower and it will have lower density. Net result is that it won't come in quite as hot and fast as Falcon, so Falcon should be a bounding case on the big booster.

    Final Falcon 9 has a lot of minor refinements that collectively are important, but uprated thrust and improved legs are the most significant.

    Actually, I think the F9 boosters could be used almost indefinitely, so long as there is scheduled maintenance and careful inspections. Falcon 9 Block 5 -- the final version in the series -- is the one that has the most performance and is designed for easy reuse, so it just makes sense to focus on that long term and retire the earlier versions. Block 5 starts production in about 3 months and initial flight is in 6 to 8 months, so there isn't much point in ground testing Block 3 or 4 much beyond a few reflights.

    With sub-cooled propellant, I think we can get the Falcon 9 upper stage mass ratio (excluding payload) to somewhere between 25 and 30. Another way of saying that is the upper stage would be close to 97% propellant by mass.

    [Merlin engine lifetime?] There is no meaningful limit. We would have to replace a few parts that experience thermal stress after 40 cycles, but the rest of the engine would be fine.

    Big LOX tank?

    EM: The flight tank will actually be slightly longer than the development tank shown, but the same diameter.

    That was built with latest and greatest carbon fiber prepreg. In theory, it should hold cryogenic propellant without leaking and without a sealing linker. Early tests are promising.

    Will take it up to 2/3 of burst pressure on an ocean barge in the coming weeks.

    Spaceship/tanker flipperons?

    EM: Good question -- that wasn't shown at IAC. The spaceship and tanker would have split body flaps for pitch and roll. Probably just use the attitude control thrusters for yaw.

    Favorite teacher?

    EM: The best teacher I ever had was my elementary school principal. Our math teacher quit for some reason and he decided to sub in himself for math and accelerate the syllabus by a year.

    We had to work like the house was on fire for the first half of the lesson and do extra homework, but then we got to hear stories of when he was a soldier in WWII. If you didn't do the work, you didn't get to hear the stories. Everybody did the work.
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    Moderator Dr Mordrid's Avatar
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    The ITS spaceship alone will have almost as much max thrust as the Saturn V booster.

    Composite spaceship LOX development tank



    Placement



    vs Saturn V

    Dr. Mordrid
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    Are they considering some shielding against radiation?

    Not so long ago there were articles linking galactic radiation with dementia, paranoia, etc..
    http://phys.org/news/2016-10-mars-bo...-galactic.html
    pixar
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    Mars has small magnetic field and bad shielding.

    Venus would have been better if you could change it's spin as it has more similar gravity to Earth and has the magnetic field.

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    How does one fill a carbon container with oxygen and not have it explode?
    Edit: Oh, I see that's sort of answered above. I wonder what they will go with.
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    Quote Originally Posted by cjolley View Post
    How does one fill a carbon container with oxygen and not have it explode?
    Edit: Oh, I see that's sort of answered above. I wonder what they will go with.
    The tank liner (called a bladder) is made from forged lithium metal or aluminium, then it wrapped with Carbon Fiber and resin. The really critical part is the resin; it needs to have a wide temperature range and good resistance to radiation. Not all materials can be made radioactive, but the stability of those materials when exposed to radiation can be compromised.
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    Quote Originally Posted by Dr Mordrid View Post

    Placement


    I couldn't help think it odd that they'd place the humans in that illustration (for scale) inside the fuel tank instead of in the passenger section of the ship. Surely you'd think it'd serve the same purpose.

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    Quote Originally Posted by MultimediaMan View Post
    The tank liner (called a bladder) is made from forged lithium metal or aluminium...
    The pure liquid oxygen directly contacts one of those metals?
    Seems like that would be far worse than even carbon.
    Chuck
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    Super MURCer MultimediaMan's Avatar
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    Quote Originally Posted by cjolley View Post
    The pure liquid oxygen directly contacts one of those metals?
    Seems like that would be far worse than even carbon.
    Happens every day... Lithium Tanks are ultra lightweight ultra-high pressure (8000-22000PSI+) developed in the late 1980's. Fiber-Wrapped Aluminum tanks have been used for decades... I have three of them myself I use for my Air Rifles. There are lifespan and inspection requirements which have to be met (a 15 year lifespan from the date of manufacture {required only in the USA}, a visual and hydro inspection every 5 years), but these tanks are common.... Firefighters have been using Fiber-wrapped tanks for 20 years and more.
    Hey, Donny! We got us a German who wants to die for his country... Oblige him. - Lt. Aldo Raine

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