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if there's one thing that sets SpaceX
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apart from their competition in the
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Aerospace industry it's the courage to
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dream up crazy ideas that no one else
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would even consider to be
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possible if there's a second thing that
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makes SpaceX a very special company it's
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their ability to take those crazy ideas
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and actually make them into a reality
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and the starship's Raptor engine is a
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perfect example of this innovation in
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action the Raptor is more than just
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another rocket engine it is the rocket
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engine
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reinvented let's start at the beginning
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with the first production rocket engine
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from SpaceX the Merlin we saw a few
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different iterations of the Merlin
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design as SpaceX progressed with their
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initial Falcon 1 rocket testing the
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Merlin 1C was the engine that powered
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the first successful Falcon 1 launch and
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went on to be used in the first five
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flights of the Falcon 9 SpaceX is
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currently using the Merlin 1D engine
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across their full line of Falcon 9 and
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Falcon heavy boosters the design of the
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Merlin engine was a product of the
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chaotic early days in the life of SpaceX
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to have a private Tech startup company
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from California enter into the field of
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orbital rocket launches was outrageous
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back in the early 2000s unprecedented no
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one thought they would succeed and
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therefore no one was investing any money
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in the project Elon Musk was self-
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financing the whole thing with his
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Paypal Fortune which was a lot of money
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but SpaceX was burning through cash as
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fast as they were burning Rocket Fuel so
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elon's mission statement for the Merlin
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was to build a rocket engine as simple
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and cheap as possible so what does that
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look like let's talk briefly about how
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rocket engine works just so we're all on
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the same page the basic concept here is
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actually not that hard to grasp inside
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the main body of a rocket there are two
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propellant tanks one is for oxygen the
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other is for fuel the oxygen side is the
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same for every kind of Rocket because
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fire needs oxygen to burn this is like
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blowing air into your campfire to
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intensify the Flames to make oxygen into
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rocket propellant you first have to
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liquefy it you convert oxygen from a gas
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to a liquid state by super cooling it to
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a cryogenic temperature the boiling
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point of oxygen is
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83° C or - 297 F so at any temperature
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below that it will stabilize as a liquid
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it's pretty cool then on the fuel side
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the Merlin uses a chemical called rp1
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which is basically just purified
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kerosene it's cheap and accessible and
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is liquid at ambient temperature when
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the rocket engine starts two pumps will
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move both the oxygen and fuel at very
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high pressure into the combustion
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chamber where the two liquids are
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combined and ignited and that combustion
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is going to release a massive amount of
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energy as the propellants burn and
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expand to create pressure all of this
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energy will exit the combustion chamber
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through the throat this is like blowing
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out a candle by pushing the air in your
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lungs out through a small opening in
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your lips you create a high pressure
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inside your mouth and force the gas to
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exit through a small opening then all of
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that high pressure high temperature
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combustion exhaust exits through the
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nozzle where it expands from the size of
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the throat to the size of the nozzle
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opening this expansion actually
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accelerates the exhaust to an even
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faster speed than when it left the
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throat the greater the expansion ratio
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from the throat to the end of the nozzle
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the greater the acceleration of the
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exhaust this process converts pressure
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into thrust the faster we can throw that
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exhaust gas out of the back of the
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nozzle the faster the rocket will move
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forward every action has an equal and
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opposite reaction in the Merlin engine
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design those twin pumps for the fuel and
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oxygen are powered by something called a
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gas generator this is like a miniature
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rocket engine with its own combustion
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chamber and nozzle except instead of
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pointing straight out the bottom this
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mini engine fires directly into a
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turbine now the pressure from the
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combustion reaction is spinning a
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turbine which is connected to a main
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shaft that power ERS both of the main
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fuel and oxygen pumps after the gas has
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done its work of spitting up the turbine
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the excess is vented out the side of the
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engine through an exhaust pipe this is
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what we call an open cycle gas generator
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and this design goes all the way back to
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1944 and the first longrange ballistic
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missile ever created the German V2
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rocket so when Elon asked for the
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easiest and cheapest rocket engine
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possible this is exactly what he got now
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imagine being able to see this
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incredible view of outer space through
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today the Merlin engine continues to be
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a fantastic product for SpaceX right up
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until this day and it will probably
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continue on like that for several years
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but when it came time to begin
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development on the next generation of
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SpaceX vehicle it was going to require
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the next generation of SpaceX Engine
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with the Starship Elon Musk had a new
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mission statement for his engineers
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build the most complex rocket engine
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ever made give it the highest thrust to
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weight ratio of any engine in existence
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and power it with a new rocket fuel that
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no one has ever used before so the time
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to just fall back on classic designs
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from the 20th century was now long gone
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this was time to reinvent the rocket
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engine so let's start with the new fuel
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source instead of kerosene the Raptor is
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now burning methane Just Like Oxygen
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methane needs to be liquefied at a
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cryogenic temperature to make it into a
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suitable Rocket Fuel so that adds an
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extra layer of complexity to the system
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but it's worth the trouble let me
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explain kerosene is a longchain
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hydrocarb carbon which means that it is
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very difficult to fully combust and
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convert into gas you're going to end up
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with a lot of solid matter Left Behind
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as a byproduct of the combustion even
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inside an environment like the
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combustion chamber of a rocket that
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leftover carbon solid is what we would
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typically refer to as soot just black
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dust and the same as the inside of a
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chimney that soot has a tendency to
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cling onto the inside of a rocket engine
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and cause a buildup known as cing now
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since a typical rocket engine goes
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straight to the bottom of the ocean
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after being used once that typically
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doesn't matter but in a reusable engine
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like the Merlin that cing all needs to
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be scrubbed out in between launches and
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that's just not going to cut it with the
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Rapid reusability schedule that Elon has
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in mind for Starship he wants these
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things launching multiple times per day
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methane is mostly hydrogen with one
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single atom of carbon for every four
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atoms of hydrogen so it's pretty easy to
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fully combust that carbon and leave
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nothing behind as a byproduct for
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example if you have natural gas in your
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home that's almost entirely methane and
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you can burn it all day in your furnace
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or stove without having to worry about
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carbon residue so that's fuel now how
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does the internal system of a Raptor
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engine compare to the old Merlin the
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design of the Raptor is called a full
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flow staged combustion cycle and it's an
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exceptionally complex layout of pumps
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turbines and plumbing let's go back to
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our engine diagram in the Raptor cycle
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the liquids move from the tanks to the
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main pumps and then directly into a pair
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of gas generators both the fuel and
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oxygen hit their own individual turbines
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so unlike every previous engine which
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has used a single turbine either on the
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oxygen side or in rare cases the fuel
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side the Raptor is the only Engine with
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dual gas turbines now instead of
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everything rotating on one main shaft we
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have independent turbines and pumps for
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each tank when the cryogenic liquid
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reaches these turbines the first thing
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it will encounter is a pre- burner
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that's a miniature rocket engine and the
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pre- burner combusts the liquid just
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enough to transform it into a gas but
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since neither the oxygen or the methane
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can combust on their own there needs to
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be a cross connection between the two
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pre-burners that allows a little bit of
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oxygen to join the methane flow and a
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little bit of methane to join the oxygen
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flow once combustion is achieved the
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exhaust gas is blasted into the turbine
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housing where it spins the blade the
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turbine blade spins the pump and that
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sends our now gaseous propellants into
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the combustion chamber at extreme
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pressure but wait a second if the
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turbine spins the pump and the pump
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sends the liquid into the turbine then
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how does the process get started in the
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first place well SpaceX uses equipment
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on the launch Mount to externally spin
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start the turbines this is why the
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Starship launch Mount is considered to
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be a stage zero for the main rocket it
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is integral to the successful ignition
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of the booster two things to note here
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number one this system has no exhaust
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pipe for the gas to escape after the
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turbine that's why we call the Raptor a
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closed cycle as opposed to the Merlin's
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open cycle so in a raptor all of the
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pressure from both of the gas generators
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is held inside the system making this an
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extremely high pressure operation this
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is also another area where methane
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shines as a clean burning fuel source
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because we are not venting the exhaust
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from the pre-b burner if you tried this
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with kerosene fuel the soot would very
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quickly build up inside the system and
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ruin everything number two there is no
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direct path from the fuel or oxygen pump
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to the combustion chamber that means all
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of the methane and all of the oxygen
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have to pass through a pre-b burner
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before they reach the chamber this is
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why we call the Raptor cycle full flow
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staged combustion so now we have both
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our oxygen and methane exiting their
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turbines as very hot and very high-press
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gases and that gas on gas reaction when
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they hit the combustion chamber is going
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to produce the most efficient combustion
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possible significantly more energy is
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going to be generated by gas on gas than
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by liquid on liquid Elon Musk claims
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that this reaction is over 99% efficient
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the maximum that physics will allow Elon
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says that only God himself could
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possibly do a better job at combining
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molecules than the Raptor combustion
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chamber now if that all sounded very
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complicated that's because it is it's
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rocket science after all Elon has
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referred to igniting the Raptor engine
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as a delicate dance between the fuel
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system and the oxygen system everything
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is interconnected and everything affects
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everything else so if anything goes
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wrong or even if the methane and oxygen
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cycle gets even slightly out of sync
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with each other then the whole engine
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will explode or at the very least parts
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will melt so we know how the Raptor does
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what it does let's talk about what all
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that means for the performance and power
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of this engine the Raptor is a
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relatively small engine that produces a
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relatively massive amount of thrust the
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current Raptor version 2 is creating 230
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metric tons of thrust at sea level this
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is not the most powerful rocket engine
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that title goes to the F1 engine that
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lifted the Saturn 5 rocket it had more
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than twice the thrust of a Raptor but it
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was also an absolutely humongous engine
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that you could park a Jeep inside of by
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comparison the Raptor is super compact
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at 3 m tall and 1.5 M wide at the nozzle
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this allows SpaceX to pack 33 of them
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into the 9 M diameter booster raptor is
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much smaller than a close equivalent
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such as the rs25 engines that powered
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the space shuttle and have also been
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adapted to the SLS Moon rocket but the
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rs25 only produces about 1990 metric
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tons of thrust so Raptor has an
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unmatched power to weight ratio the
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Raptor weighs in at just 1,600 kg while
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the rs25 is nearly 3200 kg and Raptor
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accomplishes this by running the
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combustion chamber at significantly
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higher pressure than any other rocket
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engine in the world the Raptor 2 chamber
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pressure is currently 300 bar which
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converts to about
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4,351 lb per square in for comparison
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the old Merlin engine chamber pressure
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is down at around 100 bar remember that
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the rocket engine uses the throat and
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the nozzle to convert pressure into
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thrust so more pressure means more
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thrust Elon Musk says that the work
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going forward on the Raptor design will
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be primarily to make the engine more
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simplified and therefore cheaper and
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faster to produce this comes back to one
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of elon's favorite sayings the best part
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is no part which is at the core of his
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first principles philosophy the steps
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that Elon follows when he's designing
00:14:42
something are to first question the
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constraints and requirements and make
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them less dumb AKA don't follow any rule
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that doesn't make sense then second
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delete any part of the design process
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that isn't necessary if you aren't
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forced to put back at least 10% of the
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things that that you deleted then you
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didn't delete enough step three optimize
00:15:04
step four accelerate step five automate
00:15:07
and we can already see that in action
00:15:09
with the transition from raptor 1 to
00:15:11
Raptor 2 there are significantly fewer
00:15:14
Parts visible on the new engine Elon
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says that he wants to delete all of the
00:15:18
fiddly bits from the engine that means
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integrating more of the small pipes and
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wiring into larger conduits and
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replacing bolted fanges and solid welds
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Elon says that by integrating more
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components of the engine they can
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actually remove the shrouds which are
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essentially protective heat shields
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obviously removing anything from a
00:15:38
rocket ship design is going to make it
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lighter and cheaper which is absolutely
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critical for sustainable space flight
00:15:46
this process will also continue to make
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Raptor cheaper and more production
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friendly which is the ultimate main goal
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you may wonder why do they need so many
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engines if the rocket is going to be
00:15:57
fully reusable well we've got to think
00:16:00
longer term here that's where elon's
00:16:02
head is at his end goal with Starship is
00:16:04
to make these Rockets as common as jet
00:16:07
airliners are today a fleet numbering at
00:16:10
least 1,000 ships or more these ships
00:16:13
would be in constant operation for
00:16:15
Transit between the Earth and Mars the
00:16:18
Earth and the moon or even using the
00:16:20
ship as a point-to-point transport on
00:16:22
the Earth itself the endgame of the
00:16:25
Starship is to become one of the most
00:16:26
important vehicles ever created in human
00:16:29
history this is right up there with the
00:16:32
first sailing ships that crossed the
00:16:33
ocean and connected the globe the
00:16:36
Starship can connect the solar system
