Hovercrafts:

A Demonstration of Air Flow and Pressure

Submitted to:

Professor Susan Finger

Carnegie Mellon University

Submitted By:

Suman Grandhi

Sophomore, Electrical & Computer Engineering

Amy Ng

Junior, Mechanical Engineering

Armando Morreale

Senior, Mechanical Engineering

April 7^th, 1998

Introduction

Stimulating the imaginations of young students involves associating engineering concepts with a fun and interesting activity. By bringing innovative activity boxes into student classrooms, we generate interest in engineering and scientific concepts. The proposed project teaches students about the principles of frictionless surfaces, airflow patterns, and pressure. After a demonstration of these principles, the students will then be engaged in a lightly competitive game.

Problem & Objectives

An activity box is the ideal setup for an instructor to coordinate an outreach project with students in Elementary and Junior High Schools. The materials in the box are safe, durable, and suitable for an indoor classroom. The activity engages up to 30 students in the 5^th to 6^th grades, and introduces the concepts of pressure, airflow patterns, and frictionless surfaces.

The instructor demonstrates these concepts by using the manufactured prototype of the hovercraft. Glitter is placed onto the surface so that as the air flows out of the hovercraft, the patterns are visible to the students. As the instructor demonstrates the working concepts of the hovercraft, he will also ask the students to consider several questions as to why certain things are happening. With this question and answer session, students will develop an understanding of the engineering principles of air flow.

Plan

The design and activity concepts have been developed and agreed upon. The remaining tasks to be accomplished include (by order of importance):

• Rapid manufacturing the instructor’s demonstration prototype
• Rapid manufacturing the Board-Cutters
• Creating a list of instructions for the outreach coordinator or teacher
• Creating the props or targets for the game
• Perform user testing with a nine year old child
• Present the final project to the class.

Solution

The game that the young children will play will be very straightforward and will also be very fun. The game itself is very similar to curtling, bocce, and shuffleboard. First, the child will be supplied with the materials to manufacture his/her own hovercraft. After the hovercraft has been assembled from the given parts, the child will proceed to blow up a balloon and place it on the hovercraft. Now the child is ready to play the game.

The game itself consists of a playing surface similar to the one in the sport of curtling. That is, there exists a bulls-eye at the end of the playing surface. This bulls-eye will have a variety of different colored rings, each corresponding to a certain point value. Naturally, the center of the bulls-eye will be worth the most.

Picture of the bulls-eye board!

The playing surface will be made of a roll of transparent vinyl, similar to the transparency rolls used by professors while lecturing with an overhead projector. The transparency roll would suffice, but it is only 11" wide. The vinyl rolls are approximately 3" wide. This provides for a spacious playing surface. Also, the surface of the vinyl roll is very smooth, creating an almost frictionless interface between it and the hovercraft. The roll of vinyl will be unraveled on top of a table in order to play the game. The bulls-eye will be drawn on a large piece of paper and will be placed underneath the end of the playing surface.

The picture above shows a rough image of what the game surface might look like. The rules of the game are to slide the hovercraft down the game board onto the bulls-eye. As stated before, the center of the bulls-eye will be worth the most points, while each larger ring represents a smaller point value. Each child will be able to slide his/her own hovercraft down the playing surface two times. The total score will be the sum of the two different point scores for each of the individual turns taken. The child with the highest score at the end of the game will win.

PARTS LIST:

Rapid Manufactured Items

• Balloon Clips (Qty. 31): Used to prevent air leaking out of fully inflated balloon. These ease the skill required to attach the mouth of the balloon to the hovercrafts base when the balloon is inflated.

• Cardboard Cutters (Qty. 3): Helps children cut out symmetric figures from the cardboard allowing them to have the most optimal working hovercrafts.

• Clear Demonstration Hovercraft (Qty. 1): Allows children to visualize how the air released from the balloon forms a cushion of air between the hovercraft and the surface top. They will be able to see the airflow by watching the movement of colored dust placed under the clear hovercrafts.

Purchased Items

Hovercraft Items:

• Glue – to glue spools to cardboard base
• Balloons – acts as an air reservoir
• Wood spools – hole controls air flow from balloon
• Cardboard – used to act as a base for hovercraft
• Colored Powder – used in demo to help visualize air flow
• Glass Rods – helps prevent air hole from being clogged with glue

Bulls-eye Items:

• Colored Markers – for coloring the bulls-eye
• Poster Board – for coloring on to make the bullseye

COST:

Glue: $ 0.80 * 15 = $ 12.00

15-pack 12" Balloons: $ 1.29 * 2 = $ 2.58

18-pack Wooden Spools: $ 2.00 * 2 = $ 4.00

Cardboard: $ 2.00 * 1 = $ 2.00

Colored Powder: $ 3.00 * 1 = $ 3.00

Glass Rods: $ 0.50 * 15 = $ 7.50

Colored Markers: $ 5.00 * 1 = $ 5.00

Poster Board: $ 1.00 * 1 = $ 1.00

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TOTAL: $ 37.08 + tax