Tamaki college

Rocket science – the factsBefore we begin the design and construction of our bottle rockets it is important we understand some of the science behind the fun. The next few pages detail how rockets work and the uses we have for them from entertainment to our exploration of outer space.

How does a rocket work?

If a balloon is filled with air and then released it speeds along – a rocket works in the same way. A mixture of hydrogen and oxygen fuel explodes all the time, pushing hot gas out of the back of the rocket and propelling it along.

Firework rockets are the simplest form of heat engine. They are packed with a propellant, a powder that burns fiercely. The smoke and hot gases stream from the base and drive the rocket upwards, while the long stick keeps the rocket’s flight straight. The propellant is slowly consumed by combustion, and finally the burning powder ignites an explosive charge which expels the glowing stars.

How are spacecraft launched?

Earth’s gravity is so strong that rockets are needed to propel satellites and other spacecraft out of the atmosphere and into space. Many spacecraft are launched by solid-fuel boosters, which are rocket engines that, like firework rockets, contain a solid propellant. Solid-fuel rockets can produce great power but, once ignited, they cannot be shut down; they fly until all the propellant has burned.

Spacecraft that require repeated firings of their engines, often for manoeuvring in space, have liquid-fuel rocket engines. Liquid hydrogen and liquid oxygen are often used.

The space shuttle has five principal rocket engines. These are two huge solid-fuel boosters fixed alongside the orbiter, and three liquid-fuel main engines at the rear of the orbiter. These five engines only take the shuttle into space. Other smaller liquid-fuel engines are used to attain and level orbit and to manoeuvre the shuttle in space.

What happens to rockets after launching a spacecraft?

Rockets are only needed for the first few seconds of a spacecraft’s journey.

They then fall back down to Earth, land in the sea and are recovered by special ships.

How do spacecraft land back on Earth safely?

Spacecraft such as Apollo and Soyuz both land in the sea when they come back to Earth.

However, the Space Shuttle is specially designed to land like a normal aeroplane on a runway.

Design team Organise yourselves into groups of no more than five people.You will need:

Project team supervisor 2 x design engineers

2 x construction team

You will need to collect:

1 plastic pop bottle scissors ruler string duct tape or glue coloured pens coloured card or paper

The Project team supervisor will be responsible for overall control of the rocket design and build process. They will ensure the team works together and co-operates at all stages of the design and build process.

The design engineers will be responsible for the design of the rocket. In particular, the nose cone, tail fins and rocket livery i.e. any external decorations such as flags or names.

Construction The construction team will be responsible for the final assembly of the rocket and at this stage of the project all team members will be involved in completing the rocket under their supervision.

Design information – your missionCreate one bottle rocket that will fly straight and remain aloft for a maximum amount of time.

Part one: the tail finsUse scrap paper to work out the size of fins needed for your rocket. Once you have got the size correct then use this scrap paper as a template and get the coloured card; fins will

be made from it. Cut three shapes out of the folded bottom in the shape that the diagram shows. Your fins will be triangular.

 

 

The next drawing indicates how the fin should look once folded.

Mark straight lines on the bottle by putting the bottle in the door frame or a right angle and trace a line on the bottle with a marker. Use these lines as guides to place the fins on the bottles. 

Make three fins and tape them on the rocket. Be sure that the fins are spaced equally around the rocket body. This can be achieved by using a piece of string and wrapping it around the bottle and marking the string where it meets the end. Mark the string and lay it flat on a metre-stick or ruler. Find the circumference of the bottle by measuring the length of the string to the mark. Once you know the circumference, then you can divide it by three to find the distances the fins should be separated. Secure the fins to your bottle with duct tape.

Part two: the nose coneUse the scrap paper to make a template for your nose cone. Once you have got the size correct then use this scrap paper as a template and get the coloured card; the cone will be made from it. Then, using scissors, cut out the nose cone shape and trim the cone to make it symmetrical. Use your plastic bottle to check your cone will fit properly. (Hint: the diameter of the bottom of the cone should be a little wider than the diameter of your plastic pop bottle).

The picture above gives you an idea of the approximate shape that the nose cone should be. Secure the nose cone to the top of the rocket using glue or duct tape.

Part three: the liveryNow the major parts of construction are completed, it is time to name and decorate your rocket. Use plain or coloured paper and pens to do this.

You may like to include a flag or put the names of your team members on the outside of the rocket. At this stage of the process you can be as creative as you like so have fun!

Important informationIn order to be successful throughout the different stages of this project it is important that all team members contribute and do the following:

listen and respect other peoples ideas and suggestions have sensible discussions when necessary co-operate and work together as a team

On launch dayOnce all rockets are completed and ready for lift off all teams will move to the launch area (the sports field) and from a safe distance will observe the rocket launches taking place that day.

Whilst waiting for your team’s rocket launch you are asked to remain behind the safety barrier and most importantly to wait quietly and behave sensibly.

Stay safe andhave

fun out there!