remotely by telemotors, early servomechanisms operated electrically or by hydraulics. Maintaining depth in a submarine is a sophisticated task. The planesman was provided with a prominent depth gauge to monitor this, usually a circular Bourdon gauge. For precise maintenance at periscope depth an additional shallow-depth manometer, a transparent vertical pipe, would be provided too. With the development of active sonar, depth control became even more complex. Rather than maintaining a simple depth, the planesman must now keep the boat beneath a thermocline in order to hide from sonar. To this end, the helm position may also show external water thermometers and salinometers. Early submarines had separate controls for each pair of planes, bow and stern. Together with the helmsman, this required three ratings in the already-crowded control room. By the 1960s, combined controls were introduced. These incorporated all planes onto a single aircraft-style control wheel. Cars In automotive terms, dive planes (which physically resemble submarine diving planes) are aerodynamic devices fitted on cars just ahead of the front wheels. They are most commonly found on racing cars such as the Le Mans Prototype Series and are used to create additional downforce and channel airflow to help balance the car. The 2012 Mercedes-Benz C63 AMG Black Series is one of the first road cars to feature these devices. References Submarine design Submarine components