SUBSIM Radio Room Forums - View Single Post

Sniper297 · 03-13-19, 07:32 PM

"In real life, i always thought a DD couldn’t detect a sub when all stopped below the thermal layer"

In real life you couldn't stop and "hover", you had to keep moving fast enough for the diving planes to be effective in order to maintain level depth. Trim dive TRIED to balance fore and aft and get as close as possible to neutral buoyancy, but it was very rare to get even close enough that you were rising or descending slowly at a full stop.

The game ignores those physics and allows you to stop dead even at periscope depth, in real life you could only do that for a minute or two before you'd be 10 feet deeper or shallower.

As for thermal layers, the game doesn't model those very well either. In real life they're like clouds in the sky, some higher some lower, some with sharply defined edges and some wispy, some with flat bottoms and some sloping. A sub cruising at 200 feet can enter a layer at the edge, top of the layer is at 100 feet, then it slopes downward to 500 feet 2 miles later so you move from under the layer to on top of the layer horizontally, the sub doesn't change depth but the layer boundary moves down, or even peters out altogether so there's no sudden temperature change. The thermal spike can also be strong or weak, a 10 degree change in 5 feet versus a 2 degree change in 50 feet, a weak layer won't help that much when hiding from active sonar.

The OP mentioned "800/900M", 900 meters is about about 990 yards, state of the art active sonar had about 1500 to 2000 yards effective range, so within that range the ping will pong. Aspect plays a big part, if you're broadside (the escort pinging is on either beam) he has a nice wide target to get an echo off of. He'll actually get the same strength echo if you're facing directly toward or away, the difference is it's a narrower target, so the focused ping misses 3 degrees left and the next misses 3 degrees right as he's sweeping, but if he happens to have it pointing directly at your bow or stern he gets an echo. Advantage to keeping your stern toward him is (1) it reduces the odds of a direct hit from the ping as he sweeps back and forth and (2) you're opening the range from his search circle. Reason that's important is because the ping goes out at 041, next goes out at 042, then 043, the space between the degrees becomes wider the further away you are. The pinger can get lucky and get a strong echo at 10 thousand yards if you happen to be right on the exact bearing, but the further away the less chance of a direct "hit" with the center of the sound wave.

In game, below the layer is the place to be, deeper is better.

03-13-19, 07:32 PM	#9
Sniper297 The Old Man Join Date: Dec 2005 Location: Philadelphia Shipyard Brig Posts: 1,386 Downloads: 160 Uploads: 19	"In real life, i always thought a DD couldn’t detect a sub when all stopped below the thermal layer" In real life you couldn't stop and "hover", you had to keep moving fast enough for the diving planes to be effective in order to maintain level depth. Trim dive TRIED to balance fore and aft and get as close as possible to neutral buoyancy, but it was very rare to get even close enough that you were rising or descending slowly at a full stop. The game ignores those physics and allows you to stop dead even at periscope depth, in real life you could only do that for a minute or two before you'd be 10 feet deeper or shallower. As for thermal layers, the game doesn't model those very well either. In real life they're like clouds in the sky, some higher some lower, some with sharply defined edges and some wispy, some with flat bottoms and some sloping. A sub cruising at 200 feet can enter a layer at the edge, top of the layer is at 100 feet, then it slopes downward to 500 feet 2 miles later so you move from under the layer to on top of the layer horizontally, the sub doesn't change depth but the layer boundary moves down, or even peters out altogether so there's no sudden temperature change. The thermal spike can also be strong or weak, a 10 degree change in 5 feet versus a 2 degree change in 50 feet, a weak layer won't help that much when hiding from active sonar. The OP mentioned "800/900M", 900 meters is about about 990 yards, state of the art active sonar had about 1500 to 2000 yards effective range, so within that range the ping will pong. Aspect plays a big part, if you're broadside (the escort pinging is on either beam) he has a nice wide target to get an echo off of. He'll actually get the same strength echo if you're facing directly toward or away, the difference is it's a narrower target, so the focused ping misses 3 degrees left and the next misses 3 degrees right as he's sweeping, but if he happens to have it pointing directly at your bow or stern he gets an echo. Advantage to keeping your stern toward him is (1) it reduces the odds of a direct hit from the ping as he sweeps back and forth and (2) you're opening the range from his search circle. Reason that's important is because the ping goes out at 041, next goes out at 042, then 043, the space between the degrees becomes wider the further away you are. The pinger can get lucky and get a strong echo at 10 thousand yards if you happen to be right on the exact bearing, but the further away the less chance of a direct "hit" with the center of the sound wave. In game, below the layer is the place to be, deeper is better.