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Old 01-31-2011, 09:05 PM   #3
Join Date: Apr 2004
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In real submarines, you can determine the depression/elevation of the sound hitting your array. With a spherical array, the tracker automatically tracks both bearing and d/e angle. The towed array has conical beams, so the angle measured by the tracker is always a mix between vertical and horizontal components. But if you put the contact on your beam, you get his bearing, and if you put him on your bow, you get the d/e angle. Because sound bends and bounces so much in the water, the vertical angle is ignored a lot of the time, but under certain conditions, it can help you determine the range to the contact. If you knew the exact path the sound is taking and you knew the exact range to the target, you could in theory estimate the depth of the contact. However, passively derived information is seldom anywhere near accurate enough to predict target depth. In relatively shallow water with the right bottom type, the d/e angle can be used to estimate range assuming bottom bounce path with a single bounce. The inability to determine the depth of the target is not very critical except in two circumstances: close aboard contact and torpedo presets. With close aboard contacts, the bearing rate is so high that you don't care about the d/e angle, you just maneuver as best as possible to avoid a collision. Torpedoes with wire guidance can let you know where the target is if they can acquire it, but their beams are somewhat narrow, so if your best guess at the target depth is wrong, or the target changes depth, you may never find it with the seeker. Fortunately, most sub captains respond to torpedo shots with all-ahead flank, allowing passive means to be used to continue tracking the target even if the depth is wrong. The hardest targets to find and kill are those that are dead quiet, aren't moving relative to the line of sight, and are masked by surface clutter (stormy waves, heavy rain, etc.) or bottom clutter (especially bottoms that reflect active frequencies). Having the courage to come to a stop near the surface or bottom while a torpedo is coming is something few sub captains have, but there isn't a torpedo in the world that can find and hit such a target except by luck. Of course, if aircraft are around, hanging out near the surface is a death wish due to visual and MAD detection risks. In "blue water" combat with fair weather, there is no bottom or waves to mask the sub, so playing depth and course change games are about all you can do to foil an opponent that has detected you. The Baton Rouge came up with a great way to completely solve the range, depth, and classification problems encountered during cold war sub chases. Point at the contact until you hear the ring of steel hulls bouncing off each other (range 0, depth within 20 to 40 feet of yours), then go to periscope depth to classify the contact visually when he surfaces to assess the damage.
former STS1(SS) on USS Dolphin AGSS-555 1994-1997
STS2(SS) on USS Richard B Russell SSN-687 1990-1994
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