The air gap between tape and drum in a video recorder

Lubrication with ambient air is not quite generally applied. The best known application is the "oil bearing" in tape recording systems for audio, video and computer applications; where the gap height that is needed for effective lubrication may quite easily be attained. This air gap reduces tape friction and wear of tape and recording head substantially. On the other hand, though, the air gap for effective magnetic recording is very small. These conflicting demands on the lubrication conditions ask for an accurate calculation of the air gap distribution. The multigrid method — a fast, iterative equation solver — will be applied to calculate the film thickness in foil bearings on a fine grid. The results for a simple but adequate model for the air lubrication between the tape and the drum in a VHS-recorder will be presented, including details about the narrow gap between recording head and tape.