ABSTRACT:

A depth and roll controllable towed vehicle, DRAKE, was developed to measure the ocean currents, and its structure and performance are described in this paper. The performance confirmed in on-site experiments on an observed course across the Kuroshio are compared with the theoretical estimations obtained using a three dimensional numerical simulation method. Comparison indicates that the performance of DRAKE obtained In experiments was In good agreement with theoretical estimations.

INTRODUCTION

Many kinds of underwater vehicles have recently been developed for various purposes Towed vehicle systems are most appropriate for ocean measurements over wide areas because of their high speed mobility and reliable mechanism We developed "DRAKE" (Depth and Roll Adjustable Kite for measuring Energy flux of the Kuroshio), this -is a towed Vehicle system which carries an acoustic Doppler current profiler and CTD (conductivity, temperature and depth) sensor The current profiler demands a high level of stability In the pitch, roll and heave of the towed vehicle, therefore, the main wings and the tall wings of DRAKE are controlled automatically to maintain the operation at a stable submerged depth and roll The towing point is selected so that the trim and pitch angles are minimized under any conditions Excellent theoretical studies on dynamics of a towed vehicle and towing cable were done at the University of Bath (Chapman, 1984), but, they were not fully three-dimensional An outstanding study In connection with- the development of the" Batfish" was carried out by Dessureault (1976), but he was not Interested In theoretical work on the dynamics of a towed vehicle. Four kinds of tests were carried out the first was a towing test at various submerged depths to investigate the static characteristics of DRAKE, such as the main wing angle, trim angle and cable tension versus the command depth.

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