SpaceX First Land Landing
In December, 2015, the Falcon 9 rocket delivered
11 communications satellites to orbit, and
the first stage returned and landed at landing
zone 1, the first ever orbital class rocket
landing.
Making the commercial spaceflight a reality;
curious to know more about Falcon 9 and reusable
launch systems?
KEEP WATCHING!!
It’s crucial to understand how rockets really
work along with their launch stages in order
to appreciate the significance of reusable
launch systems.
First of all, there are four major systems
in a full scale rocket, the structural system,
the payload system, the guidance system and
the propulsion system.
The structural system or frame, is similar
to the fuselage of an airplane.
The frame is made from very strong but lightweight
materials, like titanium or aluminium and
usually employs long stringers that run from
the top to the bottom and they are connected
to hoops which run around its circumference.
The skin skin is then attached to the stringers
and hoops to form the basic shape of the rocket.
It may be coated with a thermal protection
system to keep out the heat of air friction
during flight and to keep in the cold temperature
needed for certain fuels and oxidizers.
Additionally, fins are attached to some rockets
at the bottom of the frame to provide stability
during the flight.
The payload system of a rocket depends on
the rocket’s mission.
Most of the rockets are specified to launch
satellites with a wide range of missions;
such as communications, weather monitoring,
spying, planetary exploration and observatories
like the Hubble Space Telescope.
Moreover, Special rockets were developed to
launch people into earth orbit and to the
surface of the moon.
The guidance system of a rocket may include
very sophisticated sensors, on-board computers,
radars and communications equipment in order
to maneuver the rocket in flight.
Many different methods have been developed
to control rockets in flights.
For example, the V2 guidance system included
small vanes in the exhaust of the nozzle to
deflect the thrust from the engine.
However, Modern rockets typically rotate the
nozzle to maneuver the rocket.
The guidance system must also provide some
level of stability so that the rocket does
not tumble in flight.
The propulsion system constitutes most of
the full scale rocket’s body.
There are two main classes of propulsion systems,
liquid rocket engines and solid rocket engines.
For example, the V2 used a liquid rocket engine
consisting of fuel and oxidizer or propellant
tanks, pumps, a combustion chamber with nozzle
and the associated plumbing.
On the other hand, the space shuttles Delta
II and Titan III all use solid rocket strap-ons.
These various rocket parts have been grouped
by function into structure, payload, guidance
and propulsion systems.
However, there are other possible groupings
where engineers often group the payload, structure,
propulsion structure and guidance into a single
empty weight parameter for the purpose of
weight determination and flight performance.
The remaining propellant weight then becomes
the only factor that changes with time when
determining rocket performance.
Secondly, rockets don’t work by “pushing
against the air” since they also function
in the vacuum of space.
Alternatively, rockets take advantage of momentum
or how much power a moving object has.
To picture this in your head, You can make
a simple analogy, imagine yourself standing
on a skateboard, if you throw a basketball
in one direction, you and the skateboard will
roll in the opposite direction to conserve
momentum.
And the faster you throw the ball, the faster
you roll backward!
Rockets work by expelling hot exhaust that
acts in the same way as basketball.
The exhaust gas molecules don’t weigh much
individually, but they exit the rocket’s
nozzle very fast; giving them a lot of momentum
as a result; the rocket moves in the opposite
direction of the exhaust with the same total
oomph.
A rocket makes exhaust by burning fuel in
its engine.
Unlike airplanes’ jet engines, rockets are
designed to work in space; they don’t have
intakes for air and they bring along their
own oxidizers which are substances that play
the role of oxygen in burning fuel.
The rocket’s fuel and oxidizer are called
propellants.
Thirdly, there are at least two stages in
the launch system of space-bound rockets,
they are sections stacked in a shared cylindrical
shell and each stage has its own engines which
can vary in number, for example, the first
stage of SpaceX’s Falcon 9 rocket has nine
engines, while the first stage of Northrop
Gruman’s Antares rocket has only two engines.
You may wonder why do rockets have stages
in the first place?
And the answer is simply because the amount
of fuel it takes to launch a rocket is so
high, therefore modern rockets use staging
launch system and once the stage has emptied
out all of its fuel, it detaches and returns
to earth so that the second stage can keep
going without having to drag along the extra
weight of the empty fuel tanks.
The first stage gets the rocket out of the
lower atmosphere, sometimes with the help
of extra side boosters.
It’s considered to be the biggest and most
powerful section of the rocket since it must
lift the entire rocket with its cargo or payload
and any unused fuel.
The faster a rocket goes, the more air resistance
it encounters.
However, the higher the rocket goes, the thinner
the atmosphere gets.
These two factors combined, mean that the
stress on a rocket rises and then falls during
a launch, peaking at a pressure known as max
q.
For SpaceX's Falcon 9, max q occurs at 80
to 90 seconds after liftoff, at altitudes
between seven and nine miles.
Once the first stage has done its job, the
rocket drops that portion and ignites its
second stage.
The second stage has a lot less to transport
and it doesn’t have to fight through the
thick lower atmosphere, so it usually has
just one engine.
At this point, rockets also let go of their
fairings, the pointed cap at the rocket’s
tip that shields what the rocket is carrying
aka the payload during the launch’s first
phase.
Historically, most of a rocket’s discarded
parts were left to fall back down to Earth
and burn up in the atmosphere.
However, starting in the 1980s with NASA’s
space shuttle, engineers designed rocket parts
that could be recovered and reused.
Private companies including SpaceX and Blue
Origin are building rockets with first stages
that return to Earth and land themselves.
The more that a rocket’s parts can be reused,
the cheaper rocket launches can get.
Before explaining Falcon 9 launch system and
its first land landing mechanism, be sure
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Passage 1
Even as SpaceX became the fIrst private company
to provide a cargo delivery service
to the ISS - a mission that was furthered
in October 2012 as the company launched its
second trip to the station - it was already
at work on its next giant leap: a reusable
orbital spaceship.
An important element in spaceX's reusability
goal is the Grasshopper program, a part of
which is the "hopping" Falcon 9 rocket.
The system was tested in October 2012 and
consists of a standard first stage with a
single Merlin ID engine in its tail and landing
legs added on.
The initial test hop was all of two meters,
but it was the first step in the company's
reusability plan that will give its boosters
the ability to launch payloads into orbit
and then land robotically so they can be refueled
and launched again.
Instead of plunging back.
to Earth and being destroyed.
Each of Falcon 9's two stages would fly back
to Earth in a controlled maneuver, using reserve
propellant to make a gentle touchdown on retractable
legs.
If successful, SpaceX could bring airlino-style
operations into LEO and significantly reduce
the exorbitant cost of leaving the planet.
A LEO reusable system would be nothing short
of a game changer in an industry whose costs
are difficult to fathom by the average person
in the street, so let's put it into some perspective:
imagine if the airline industry threw away
an airliner every time it flew across the
Pacific and you get some idea of the state
of transportation to LEO - small wonder
that space tourists have to pay upwards of
30 million dollars a flight!
But, if SpaceX can
spread the cost of a spacecraft over several
flights, access to LEO could become
much, much cheaper, perhaps even opening the
door to routine and reliable access to Space.
If SpaceX were able to achieve that, then
manned spaceflight takes on a whole new look
and it opens the door to a whole lot of new
users whose business plans suddenly become
practical.
Grasshopper may be on the right track to realizing
reusable flight but, for the system to revolutionize
spaceflight, it will have to be cost-effective
and achieve shorter turn-around times - in
the order of a few days rather than weeks.
Whatever happens in the development of Grasshopper,
the system is in stark contrast to the LEO
vision put forward by Congress.
Managed by NASA, but designed by Congress,
the heavy-lift Space Launch System (SLS) - aka
the Senate Launch System - is a monster rocket
touted as the government vehicle that will
launch astronauts to LEO some time in the
2020s.
Given the history of government designed
spacecraft, it is likely the fIrst manned
launch of the SLS will be later rather than
sooner, but will Grasshopper be operational
any earlier?
Grasshopper will be used to test reusable
vertical takeoff and landing flight regimes,
will consist of a Falcon 9 fIrst stage powered
by a single Merlin ID engine, and be equipped
with a landing structure comprising four steel
legs.
The proposed range of testing will last three
years, beginning with flights to 75 meters
and culminating in flights to a maximum altitude
of 3,500 meters.
By way of comparison, one of Blue Origin's
vertical take-off and landing test vehicles
was lost at 13,700 meters (45,000 feet) while
traveling at Mach 1.2.
Blue Origin's
attempts (and Armadillo Aerospace's among
others) at realizing a similar vehicle
suggest that what SpaceX is trying to achieve
will be anything but easy.
One of the first hurdles will be to recover
the Falcon 9 fIrst stage, which may prove
more difficult than it sounds since the vehicle's
flight profile tends to hit the atmosphere
in a "belly flop" position, severely damaging
the first stage.
One of the solutions to this problem is to
restart three of its engines after stage separation
to slow the fIrst stage, thereby easing the
transition into the atmosphere.
If this procedure were successful, the booster
would descend to a tail-first powered landing.
Assuming SpaceX can recover the fIrst stage
successfully, they then have to return the
second stage safely - a more demanding task
due to the much greater re-entry speeds.
SpaceX plans to deal with these challenges
by firing an extendable engine and adding
a heat shield at the top of the second stage,
followed by a powered landing using small
thrusters on the perimeter of the base.
SpaceX did succeed in landing the first stages
safely, and the key to that success will likely
reflect the company's unique corporate culture
and deliberate manner that enable it to follow
a plan allowing it to pursue reusability through
the normal course of its operations by means
of a parallel development effort.
Another benefIt of SpaceX's business plan
is that as long as the company can launch
its vehicles, it will be able to sequentially
test the components required to reach its
goal without interfering with market activity
and without its customers paying for much
of the effort.
It's a win-win situation that is the direct
result of SpaceX using a simple
vehicle powered by a reusable engine of its
own design that was robust enough to at
least allow the possibility of an upgrade
to reusability.
It took SpaceX a few years to get an expanded
first stage to fly back to the launch site,
but those years were likely to be granted
thanks to the company's unique business plan
and the lack of domestic competition.
Thanks for watching everyone!
Did you really understand anything new about
rockets and their launch systems?
Do you think that spaceflight is a luxury
we should enjoy?
Let me know what you think in the comments
below, be sure to subscribe, and I’ll see
you next time on the channel!
