Quote:
Originally Posted by Edwin
I've always wondered why the 15% percent figure keeps getting quoted as there's no real source behind it. The German tests came up as follows (from Cold War, Hot Science Applied):
"Meyer and Oberst had undertaken theoretical, laboratory and full-sized trials to develop a coating that could be applied to U-boat hulls which would reduce the reflectivity of the hull to impinging sonar pulses. Their experiments demonstrated that the parameters of concern were the thickness of the hull plating and whether air or water was behind it. On this basis they developed a two-ply rubber sheet 4 mm thick, with the inner ply perforated by 2- and 5-mm holes which determined the resonant nature of the system. Although the theory proved useful, the material was developed in an empirical fashion involving the testing of some tens of thousands of different materials. Trials were carried out with a full-sized U-boat in the Skagerrak late in the war which seemed to show the efficacy of the system, with a claimed reduction in reflectivity of 20 per cent. As this was accompanied by a reduction in detection range of 60 per cent, these claims were treated sceptically by the report's translators."
60 percent is certainly a dramatic and worthwhile reduction IMO (even if it only applies to certain depths or acoustic conditions)
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But from what I've read about the system is that the adhesive was flawed. Once the rubber coating was applied, the boat would submerge and the adhesive would fail in places, causing the rubber tiles to flap in the current, actually increasing the noise signature of the boat. This is why the idea was good in theory but flawed in practice.