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BTEC SCIENCE UNIT 16 ASSIGNMENTS ACD
- Institution
- PEARSON (PEARSON)
These are fully referenced assingments A, C and D of Unit 16. I got a distinction on every one
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Assignment CSpacecraft Design
Material and Properties
Rockets are constructed to endure incredibly strong forces during flight and take-off. These
said forces are; thrust, weight, drag and lift. The structure and frame of the rocket must be
strong but at the same time light weight so that the rocket can have as much lift and thrust as
possible while remaining intact. The materials which allow this are titanium and aluminium
alloys. The frame is constructed of long "stringers'' which surround the length of the rocket
from top to bottom. These are attached to "hoops'' which circle the width/circumference of
the rocket. Upon this basic frame the skin of the rocket is attached, forming the rudimentary
shape of the rocket. During takeoff and flight the rocket is attacked by the heat of air friction,
and in order to keep this heat out the rocket skin is equipped with a thermal protection
system. This system also keeps in cold temperatures that are needed for oxidizers and fuels.
At the bottom of the rocket, fins are attached to the frame so that stability is maintained while
the rocket is in flight. (“NASA Science”)
Power Supply
The power supply of a rocket is its engines. These provide thrust to the rocket which allows
it to lift off the launch pad and take flight. The engine provides this thrust via the propulsion
system within. This happens due to Newton's third law of motion which states: for every
action there is an equal and opposite reaction.
The most powerful single combustion chamber liquid propellant rocket engine that exists is
known as the F-1 rocket engine. This engine was developed in the 1950s by Rocketdyne in
the United States. It was used most notably in the Saturn V rocket, which was the Apollo
programs main launch vehicle. A total of five of these F-1 engines were used in the first
stage of the Saturn V. (“NASA Science”)
Oxidiser and Fuel
Liquid oxygen, aka oxidiser, is carried into the rocket because there is no oxygen in space.
Oxygen is required for combustion to take place, which is needed for the engines to work and
generate thrust. The previously mentioned Saturn V rocket in particular had three stages of
fuel burning.
The first stage is at the bottom of the rocket and carries 203, 400 gallons of kerosene fuel and
318, 000 gallons of liquid oxygen (oxidiser). The second stage is located in the middle and
carries 260,000 gallons of liquid hydrogen fuel and 80,000 gallons of liquid oxygen. The
third and final stage, located at the top of the rocket, carries 66,700 gallons of liquid
hydrogen fuel and 19,359 gallons of liquid oxygen. (“ NASA Science”)
,Ceramic and carbon-carbon compound properties for protection
The universe is full of radiation, however the Earth’s atmosphere protects us from it. Space
radiation is divided into different kinds but all of these represent ionizing radiation, which is
dangerous to our health. The different kinds of space radiation are three:
1. Van Allen belts, which are particles trapped in the Earth’s magnetic field
2. Particles shot into space during solar flares and during coronal mass ejections
3. Galactic cosmic rays, which are high-energy protons and heavy ions from outside our
solar system.
The Apollo spacecraft had a thin aluminium hull. This blocks some of the radiation, but not
much. They didn't, which is why the Apollo astronauts saw blinding flashes inside their eyes
during the mission and then had a much higher probability of suffering from cataracts later in
life. (Kohlhase and Hovland)
Fuel Cells for electrical supply
Electric power for spacecraft is provided via fuel cells. This was what happened with the
Apollo command Module. It's primary source of electric power was from a set of three fuel
cells which were placed inside the service module. Every individual fuel cell combines
hydrogen and oxygen to produce water and electricity. The normal power output for each of
the power plants is 563 watts to 1420 watts, hitting a maximum of 2300 watts.
Hazards - heat, cold, micro-meteorites, fuel
components, radiation
Many accidents can and have occured when engaging in spaceflight due to the various
hazards present. The most well known or these took place on april 11, 1970. The Apollo 13
lunar landing was aborted after an oxygen tank in the service module (SM) failed two days
into its mission. This happened when a stir of an oxygen tank set alight damaged wire
insulation inside it. This triggered an explosion which caused the contents of both of the
SM's oxygen tanks to spill into space. Without oxygen the SM's propulsion and life support
systems could not operate. The CM's systems had to be shut down to conserve its remaining
resources for re-entry, this forced the crew of Apollo 13 to transfer to the LM as a lifeboat.
Now the lunar landing was cancelled and the mission controllers had to work on bringing the
crew back to earth.
Daytime on one side of the moon is about 13.5 days long, similarly darkness lasts 13.5
nights. When the sunlight hits the moon's surface during daytime, the temperature reaches up
, to 127oC. When the sun goes down and night arrives, temperatures can dip down to -280oC.
Due to this, the trips to the Moon’s surface are planned to land during lunar dawn, to ensure
the surface hadn’t had time to heat up fully to its daytime temperature. Research by NASA
found that by layering multiple metalized sheets of lightweight mylar and Kapton film, you
could make a reflective insulation which is much more effective for weight and smaller
surface area.
The Apollo lunar landers’ lower parts were wrapped in a multi-layer radiant barrier
insulation made of aluminized Mylar and Kapton film. This is a polyimide that is stable
across a large range of temperatures, from −269 to +400c.
Micrometeorites are a threat to space exploration as if long term exposure and impact by
them occurs it can threaten the functionality of spacecraft systems. These meteorites strike
the spacecraft with extremely high velocity, at around 10 kilometres per second. In order to
combat this terminal ballistics are under research. In order to protect the inner structure of the
Apollo spacecraft from micrometeoroids, it was covered in several materials. Blankets of
plastic films coated thinly with aluminium protect the spaceflight with layers of it reaching
up to 25.
A heat shield covered in titanium truss and an additional skin of carbon fibre layers was used
on the Apollo command module. This protected the capsule from the heat of re-entry. This
heat can usually melt most metals. When the Apollo capsule re-enters, the titanium truss and
composite substitute shield becomes charred and melts away which absorbs the heat. The
heat shield has several outer coverings: a pore seal, a moisture barrier, and a silver Mylar
thermal coating that looks like aluminium foil. The heat shield varied in thickness from 5.1
cm in the aft portion, which is the base of the capsule. The total weight of the shield was
around 1400kg. (“Risks of space exploration - Space exploration - National 5 Physics
Revision”)
Practicalities of Physics of Spaceflight
Lift Off principles
Newton’s laws of motion are required to understand lift off principles. Newton's first law is
the following; if the forces acting on a body are balanced then there will be zero resultant
force - the body will hence either remain at rest or move at a constant speed in a straight line.
What this means to a rocket is that it will remain on the launch pad due to the forces acting
on it remaining balanced.
Normal reaction = weight
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