June 26, 2011
June 26, 2011
June 29, 2011
Division Experimentation & Lab-Oriented Studies
22.1076.1 - 22.1076.11
Modeling Rockets in Instrumentation LabAbstractA final project for an instrumentation laboratory course was developed involving the predictionof the maximum altitude of a model rocket. The course is part of a mechanical engineering corecurriculum. The final rocket project is intended to integrate a number of methods used in thepreceding eight experiments included in the course. The rocket lab is conducted over the finalfour weeks of the semester, with one laboratory meeting per week. In the first week, the studentsassemble the rockets from kits and find the drag coefficient for each rocket using a wind tunnel.The speed of the wind tunnel is varied from 10 MPH to 100 MPH in ten steps and the drag forceis plotted as a function of the square of the velocity. The drag coefficient is then calculated fromthe slope of this plot.On the second week of the rocket sequence, the engine thrust is measured using a strain gagemounted on a ¼” x ¼” aluminum cantilever beam fitted with a machined cylinder sized for therocket motor. Using a data acquisition system, the strain on the beam is measured as a functionof time during the rocket engine ignition sequence while the rocket motor discharge is directed toa metal drum. From the data file generated from this experiment, the students calculate the thrustof the rocket motor as a function of time, employing their skills learned in their solid mechanicscourse.On the third week of the laboratory, the instructor assists the students with the development of anumerical solution, incorporating the data measured during the previous two weeks. Thestudents are required to incorporate the curve generated for thrust as a function of time, theweight of the rocket and the drag coefficient, which is to calculate the drag force as a function ofvelocity. Using this information, the students develop a computer code to numerically integratethe net force on the rocket twice as a function of time. This allows them to calculate theexpected maximum height of the rocket, based on the experimental data obtained in thelaboratory.The final experiment in the fourth week of the project involves launching the rocket andmeasuring the angle of the rocket with respect to the horizon at a known distance from thelaunch pad when the rocket reaches its highest point. This allows the actual maximum height tobe calculated and compared with the prediction from the numerical model.
McMasters, R., & Taylor, R. (2011, June), Modeling Rockets in Instrumentation Lab Paper presented at 2011 ASEE Annual Conference & Exposition, Vancouver, BC. https://peer.asee.org/18678
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