Improvements on the Control, Data Acquisition and Processing System for the Roll Damping Rig of 1.2m Wind Tunnel

The control system was developed to control, acquire and process the data from the specially designed Roll Damping Rig to measure the roll damping derivatives of aerospace vehicle models. Steady roll technique was used for these measurements in the NAL 1.2m wind tunnel. The earlier control system was configured on two separate computers, viz. one for speed control and the other for data acquisition and processing of the rolling moment data. The system required certain important parameter entries to be duplicated exactly in both the computers for synchronization of speed and acquisition of the rolling moment data. Certain other data related to the speed information were needed to be transferred from one PC to the other after the blowdown for data processing. In the new approach some modifications were made to the existing control, data acquisition and processing programs to run simultaneously in one PC. Additional features were incorporated for better performance and easy handling of the programs, and the necessary data for processing is internally transferred from one program to the other. A feature is incorporated to automatically control and acquire the data for both pre-tare and wind-on and store them with separate filenames for processing. Emergency signals from motor controller, ITCS and manual emergency were provided to stop the motor and to stop the blowdown. The control, acquisition and processing programs are integrated together to automatically control, acquire and process the data to get the roll damping derivative (Clp) values soon after the blowdown without much user intervention. The performance of the system was initially validated from bench tests and later used for the roll damping measurements on the Basic Finner and DMRJ models at various Mach Numbers in the 1.2m trisonic wind tunnel. The results of the roll damping derivatives of the Basic finner model agreed well with the previous results