Comparison of Flight Dynamics of Dropsondes

GPS dropwindsondes (dropsondes) have long been used to obtain observations of tropical cyclones (TCs). The three primary dropsondes used in TC research and observations are the Vaisala RD-94, Vaisala mini-dropsonde (mini-sonde), and the Yankee Environmental Systems eXpendable Digital Dropsonde (XDD). All three dropsondes have differences in body style and only the RD-94 and the mini-sonde use a parachute. Unfortunately, the flight dynamics of these three dropsonde types are not well understood. Specifically, the impacts of the body style, mass, and the use of a parachute on the dropsonde flight dynamics are not known. In this study, the flight dynamics of the RD-94, mini-sonde, and XDD are examined and compared in quiescent conditions. The circuit boards and instruments on each dropsonde will be comparable to ensure that there is not a bias or difference in the results due to electronics. A multi-axis inertial measurement unit will be included to fully measure the dropsonde flight dynamics. The dropsondes will be dropped from an aircraft and the flight tests will be repeated. The flight tests are crucial in order to understand and interpret the kinematic wind fields observed from dropsondes.