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Unformatted text preview: Unified Systems Problem 3 WATER BOTTLE ROCKET PERFORMANCE ANALYSIS Learning Objectives: After completing this systems problem you will have: • Applied material from 8.01, Unified thermodynamics and Unified fluid mechanics to develop a model for a single stage water rocket. • Explored how external aerodynamics, structural weight, propellant mass fraction, internal fluid mechanics and thermodynamics jointly determine the dynamic behavior of a single stage water rocket. • Demonstrated an ability to describe conceptually how the performance of the water rocket changes as a function of important design parameters. • Demonstrated an ability to integrate a system of ordinary differential equations using a spreadsheet. • Developed a preliminary design for a water rocket that you and a partner may build and test. Overview In this systems problem, you will estimate water rocket performance and analyze the impact of two design parameters on the maximum altitude achieved by the rocket. For the analysis, you will begin with a baseline rocket system that uses a standard 2-litre soda bottle for the rocket structure and fuel storage. The bottle will be partially filled with water and mounted on a rocket launch mechanism as shown in Figure 1. The air in the bottle will then be pressurized, and the launch will be executed. The launching mechanism uses a 7-inch-long rod to provide stability and to ensure that the rocket proceeds in a straight line. The bottle is inverted onto the rod, and the launcher is staked to the ground. A metal launch restraining pin is inserted over the lip of the bottle-neck to keep the bottle on the launcher until it is ready for blastoff. Air is then pumped through the rod to pressurize the bottle (slowly – assume an isothermal process); a small rubber o-ring on the launch rod provides an airtight seal at the mouth of the bottle. Figure 1. Water Bottle Rocket and Launching Mechanism The rocket launch consists of three stages. The first stage covers the period between the start of the launch until the rocket nozzle (bottle mouth) just reaches the top end of the launch rod. The second stage involves the compressed air forcing the water out of the bottle at high speed as the bottle rises into the sky....
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- Fall '05
- Dynamics, rod, vi, Vcharge