295. Electronic Scales and Precise Weight Determination

Paper

Abstract

This paper was presented at the 20th Annual National Conference of the Society of Aeronautical Weight Engineers at Akron, Ohio, May 15-18, 1961. In aircraft and space vehicles, precise information must be obtained concerning the actual weight and center of gravity of vehicles and components, in order to exercise control of these factors commensurate with the requirements of the vehicle and mission. The use of electronic scales in accomplishing these objectives is reported, together with information on the operation of the equipment, its maintenance and calibration. Data on the degree of precision with which actual weights have been determined is included, with procedures found necessary in calibration and use of electronic scales. The equipment reported on has been in daily use for several years. During the first few months” use, each system was found to have undergone a seasoning process in which significant shifts in calibration occurred. These shifts were contributed partly by the strain gage load cells and partly by the electron tube computers. Each load cell displayed a shift of different value, up to half a percent of the point reading. These shifts were compensated for by making changes in resistors in the circuits. This was done in the users’ instrument maintenance and calibration facility and proved by the use of National Bureau of standards certified test weights. Electronic scales may be used successfully in obtaining actual weight data at minimum cost, data which is consistent and accurate. Electronic scales should undergo an initial seasoning with frequent calibration. After stability has been demonstrated the time between calibrations may be lengthened to a period consistent with the amount of weighing being done.