In a helical drive tape apparatus, a rotary head drum is disposed between two sections of a split cylindrical mandrel about which a magnetic tape is guided. The head drum supports at least one magnetic transducer at its periphery, so that the total diameter of the head drum and projecting transducer is greater than the diameter of the adjacent mandrel sections. The projecting transducer has a spherical contoured portion and is configured at its leading edge, relative to the moving tape, to form an air bearing between the head and the tape. The spherical contoured portion and configured leading edge both project beyond the outer surface of the mandrel relative to the tape.
A tape recording/retrieving system includes a tape helically-wrapped about a cylindrical headwheel. When the headwheel rotates, the tape is hydrodynamically lifted above the rotating surface of the headwheel. A plurality of tape edge guides, illustratively three, disposed about the circumference of the headwheel, provide support surfaces for the tape. The edge guides include surfaces adjacent the cylindrical headwheel surface which are also subject to hydrodynamic forces when the headwheel rotates, causing the edge guides to "fly" away from the rotating surface, thus reducing wear problems on the headwheel and the guides. Using a knowledge of the system parameters, the edge guides are fabricated with a prestress so that they fly at a particular distance above the rotating surface which provides a supporting surface for the flying tape.
