The calibration rig for internal balances of the NAL-TWT (Transonic Wind Tunnel) is a system which uses component loading. In terms of the need for combination loading in the calibration of single-piece balances, it is expected that the old system must be replaced by a new one. In this paper, a description is given of a newly developed balance calibration system for the NAL-TWT. The main features of the new system are as follows: (1) full combination loading; (2) automatic operation system to reduce manpower and to realize all-night operation; (3) easy operation using menu system on the CRT (Cathode-ray Tube) display; (4) loading ranges are +/- 2,000 N, +/- 20,000 N, +/- 20,000 N, +/- 400 Nm, +/- 4,000 Nm and +/- 4,000 Nm for axial force, side force, normal force, rolling moment, pitching moment and yawing moment, respectively; (5) repositioning system; (6) double safety system for the balances against overloading; (7) four calibration bodies are equipped for the application to various sizes of the balances; (8) three formulations for balance characteristics are available: linear, second order and third order expressions; (9) electric servo motor system for safe operation and a clean room; (10) room temperature for the balance calibration rig is kept constant within +/- 1 C between 10 C and 35 C; (11) the forces applied to a balance are measured with highly accurate load cells. Calibration of these load cells is possible by using dead weight; and (12) the balance matrices after calibration are transferred to the NAL-TWT instrumentation system through a local area network at the NAL. Operation method, problems encountered and experimental data in the course of preliminary operation are also included.
内挿式6分力天秤の較正について 第2報:複合荷重式自動天秤較正装置の開発
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