A MODERNIZED CUTDOWN/LETDOWN MECHANISM FOR MOBILE BALLOON LAUNCHES

Abstract

Mobile balloon launches at The National Oceanic and AtmosphericAdministration (NOAA) National Severe Storms Laboratory (NSSL) are vital for upper air data sources and in situ observations. Instruments such as the Electric Field Meter and the Particle Size, Imaging and Velocity probe are attached to balloons to investigate the local electric field and microphysical properties in storms where direct observations are sparse. To constrain the distance flown by the package, as well as limit potential damage sustained to sensors, a cutdown mechanism releases the instrument package from the balloon. The package also features a letdown system to increase the distance between the sensor package and balloon once in flight to reduce the influence of the balloon on the measurements. To enhance reliability and ensure compliance with Federal regulations, the existing system requires modernization. This research project presents a prototype hook and latch mechanism for the cutdown application ensuring ease of use and improved operational capabilities. The reverse engineering of a gear based spool mechanism for letdown application was carried out for ease of manufacturing and optimization of recovery efforts. Additionally, the project outlines the development process of a shear pin aligned with Federal guidelines to break at a given impact force of approximately 222 N (50 pounds). A comprehensive analysis of all designed geometries was carried out using Ansys engineering software for finite element analysis (FEA), SOLIDWORKS modeling, drop testing of parts, video analysis, and theoretical force calculations. The methodology presented in this study produces a successful mechanism optimized for deployment in various severe weather field applications.