Comparing Rockets and Airplanes

BACKGROUND:

Airplanes and rockets are very important to our society. Humans have invented and improved their design to control movement in the atmosphere and space. Airplanes are important for transportation into the atmosphere and rockets are important to travel in space and for defense.

Humans, to design such machinery, must have a good idea of the physics that will make them work. Airplanes and rockets are an excellent example of how physics is used in our everyday life to control our environment. Humans were not born with wings, but it should never prevent us from flying!

Airplanes uses aerodynamic design and an engine to overcome gravity. The airplane engine uses oxygen from the air to keep the engines working. Rockets must carry their oxygen for the engines to operate.

A rocket is a generic term for a wide variety of jet propelled missiles, research vehicles, thrust devices, and fireworks. Forward motion results from a reaction to a rearward action of hot gases (Newton's

Third Law of Motion). Rocket propellants by combustion provide the hot gases that produce reaction force (thrust) when ejected to the rear.

A rocket engine is unique in that the fuel and oxidizer are self contained. Jet propulsion engines carry fuel only and use air to get oxygen. Use the enclosed picture of a rocket and a jet propulsion engine to aid in your discussion.

Development of rockets has been key to space exploration and has been used both in military and peaceful purposes for hundreds of years. Until 1955 humans were passive observers to the physics of the sky, since then space exploration has recognized no limits except the velocity of light.

At present, the rocket is the only developed engine powerful enough to put a spacecraft into orbit. It is also the only kind that will work in the mini vacuum of space, where there is no air. It carries its own oxygen and burns fuel and oxygen inside a chamber in the motor. Space rockets use a vast amount of fuel to achieve the thrust necessary for space flight. The giant Saturn V moon rocket had a thrust of nearly 8 million pounds at lift off. Each of its rocket motors burned about three tons of kerosene and oxygen each second.

PROCEDURE:

An activity that students love, but takes time and commitment, is to make a rocket and launch it. We highly recommend either having the students make the rockets or have one that you can launch for students to observe. You may find a parent that loves rocketry that might want to demonstrate for the students. If you want to make rockets, this activity is longer than one normal post lab. You may want students to complete this at home.


Go over directions on how to construct a model rocket. If you choose to use the kit model ESTES rockets, each model will have the directions in the appropriate kit.


Draw a diagram of the expected launch on the board and point out that the laws of physics can explain each part. Understanding the laws of physics enables design of machinery that performs better.

powered flight = for every action there is an opposite and equal reaction
coasts upward to peak altitude = the force of the action in our small rocket, is not great enough to free the rocket from the atmosphere, the rocket will come down due to gravitational attraction and frictional forces
recovery system opens - the parachute retards the downward descent, by increasing the air resistance


Launching the student's rockets can not only be an enjoyable experience, but also a learning event for the entire school. Depending on your school situation, you may want to share the launch with the rest of the school. This will allow all students in the school to anticipate this experience when they enter the sixth grade. Safety must be taken if you do a launch.


The launch pad does not have to be a fancy, expensive pad. It can be inexpensively made, or it can be purchased. Blasting off the engines just needs a battery to complete the circuit. You may want to have a parent who has done rocketry before to help in this launch.


Make sure you have a large, open space. Safety is important. ESTES rocket company has an excellent manual that can help your first launch be as successful as your tenth. Note that minor flaws in the rocket assembly or construction can cause large control errors. Things happen very quickly during rocket flight. Warning: Do not attempt launches when winds exceeds 10 m.p.h. Locate launch pad at portion of launch filed from which wind is blowing.


Also check city regulations by calling the local fire marshal. In some cities rockets are not allowed.


OBJECTIVES: Comparing rockets and airplanes. Learning more about rocket technology. VOCABULARY: rocket engine rocket jet propulsion MATERIALS: Estes Rocket kits (or other model rocket) books on space exploration to order: http://www.estesrockets.com	Students make model rockets.