Design And Implementation Of A Computer Data Acquisition And Control System For A Portable Wind Tunnel As A Benchmark Task In A Senior Aerospace Engineering Laboratory Class

Upper division aerospace engineering undergraduates have an introduction to the programming environment LabVIEW, data acquisition, control systems, transducer selection and calibration, and peripheral programming in their initial laboratory class. In the subsequent semester, the ability of the students to implement a complete data acquisition and control system (DACS) is tested by an assignment to develop and implement a LabVIEW program for an existing portable wind tunnel used for student orientations and classroom demonstrations. This assignment includes development of a program for control of the tunnel speed and angle of attack of an airfoil in the test section, and operation of a pressure scanning system, as well as presentation of airspeed, angleof-attack, and airfoil pressure distribution in a user-friendly display. Calibrations of potentio-metric and strain-gage based instrumentation are incidental to the programming assignment, and serve as a review of hardware selection and integration. The standard parallel port is used for digital peripheral control, and a typical data acquisition card is used for logging transducer output. Only six laboratory hours are allowed for the development and testing of the program, in two, three-hour sessions. This paper details success in the development of the current assignment, done by pairs of students, as well as difficulties encountered when larger groups of students attempted to develop the same program in parts, to be assembled during the second lab class. The teaching of basic concepts in DACS is reviewed, and student understanding of those concepts is accurately gauged through the completion of this assignment. Background discussion/motivation Upper division aerospace engineering undergraduates at Mississippi State University (MSU) take a two-course sequence of laboratory classes. In the first of these, they are introduced to the fundamental processes of data acquisition and control systems necessary to conduct various experiments. If they are to properly correlate experimental data with theoretical predictions, an understanding of the methods used to sample data is required in order to be able to properly assess the differences that appear between theory and practice. There are also limitations of equipment that will establish precision of measurements, and factors under the control of the experimenter that may affect the accuracy of the measurements. Students are never allowed to generalize errors as being