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86 Show report | Ocean Business 2021 and attitude above the seabed. “A key driver of this active control requirement was to enhance measurement quality when using a sidescan sonar,” he said. “Sidescan sonars need high stability in altitude, pitch and roll, especially when they are run at high frequency.” Roll is controlled to within ±1 º by a flaperon on each wing and pitch by an elevator on the tail surface, while the ROTV maintains an altitude of a few metres above the seabed. The FlipiX’s unusual configuration is a result of iXblue’s desire to escape the limitations of a traditional tow body, Vannuffelen explained. “It was very important to get the sonar rigidly attached to the FlipiX so that when you tow it you have very good control of its attitude,” he said. He added that iXblue cooperated closely with sonar maker EdgeTech, who helped greatly with integration, design optimisation and measurement quality. The FlipiX is largely of composite construction, to minimise the risk of interfering with towed magnetometers and compromising the accuracy of their readings. The structure also has to be strong, have positive buoyancy and be able to minimise hydrodynamic self- noise, Vannuffelen said. Another challenge, he said, was to determine the shape and profile of the FlipiX’s wing. “We went through numerous design iterations involving CAD calculations and sea tests to find the best compromise in terms of hydrodynamic performance.” Much of this testing took place at iXblue’s autonomy centre in the south of France, which provides easy access to the water, he noted. When towed behind a DriX, the FlipiX is attached to a comms-over-power cable that is winched out to a distance of between 150 and 200 m, a length that iXblue found to be a good compromise that minimised cable drag while avoiding any unwanted upward force that a steep cable angle would impose on the ROTV. Tow depth is usually 40-50 m, as the DriX-FlipiX combination is aimed at shallow water operations. In addition to the ROTV itself, iXblue has also developed a compact, rugged launch & recovery system that can be fitted to small vessels including RHIBs. Vannuffelen said this illustrates the system’s small operational footprint and minimal need for support. While it has been designed to partner with a DriX, the FlipiX can also be operated from a traditional survey vessel like any other towed body using a traditional coaxial cable, he said. Similarly, the FlipiX has an integrated ultra-short baseline (USBL) transponder designed to work with the company’s own USBL positioning system, but it can also use third-party USBL networks to allow iXblue’s systems to be as open as possible. Vannuffelen said the FlipiX’s r&d phase is complete, the system has been demonstrated internally – and publicly at the show via a video link to a live over-the-horizon demonstration – and extensively tested at iXblue’s autonomy centre. It is now being operated on behalf of clients. Oceanographic and hydrographic sensors and equipment developer Valeport chose Ocean Business to showcase four new instruments – the miniIPS2, uvSVX, SWiFT CTD and SWiFT CTDplus – and give a preview of an integrated sensor suite to be introduced later this year. The miniIPS2 is a 6000 m rated pressure sensor designed to provide vehicle pilots with real-time depth information accurate to within 0.01%, Guy Frankland told us. It features a pressure module that can be changed quickly in the field and without tools to optimise it for different depth brackets. The uvSVX calculates salinity and density data plus sound velocity profiles as standard in a compact package intended for underwater vehicles with limited internal volume, and has the same depth rating and accuracy as the miniIPS2. Available in versions rated at 10, 20, 30, 50, 100, 200, 300, 400 and 600 bar, the uvSVX features a pressure transducer that can be changed in a couple of minutes without opening the instrument. Designed to measure water conductivity, temperature and depth, the SWiFT CTD is designed for use in offshore, coastal, harbour and inland environmental and hydrographic surveys, works down to 500 m and features a new quick-response temperature probe. The CTDplus variant adds a turbidity sensor and combines direct CTD and February/March 2022 | Unmanned Systems Technology The FlipiX, from iXblue, is a remotely operated towed vehicle