LuftWolf and Amizaur's Realism Mod Poll #4: Active Sonar

[LuftWolf]

[This is primarily a free response poll]

Amizaur and I are wondering if the current cones of the active sonar systems are too wide in terms of realistic parameters, 300 degrees from the front of the ship, leaving only a 60 degree baffle for the active sonar at the rear.

This makes stalking convoys and escorts very difficult and if it were strictly a gameplay decision, we would reduce it. However, we want to check this against real world data.

[PeriscopeDepth]

Stalking convoys guarded by modern warships SHOULD be very difficult, I would think. And I see no reason why the sonar wouldn't be capable of such a wide scan area. Keep it realistic, I hate gameplay compromises.

[Amizaur]

Realistic, sure ! But is 300deg cone realistic ? :hmm:

Anyone knows what's the cone of surface ship active sonar, in general or any specific ?

[PeriscopeDepth]

Active sonar is basically sending out sound impulses and listening for returns. So why wouldn't you be able to listen to those returns in the same cone as a spherical passive sonar does?

[LuftWolf]

Well, there is some issue about whether the hull/sphere passive sonar cones are correct with only 60 degree baffle, so they would be changed together in the mod (all active sonars are hull/sphere sonars, I believe, so they would be the same as the hull passive sonar for any given platform).

[PeriscopeDepth]

And the subs too?

[LuftWolf]

The subs would probably have a greater restriction in sphere act/pas sonars because there is no "lookdown" angle increase.

But these kinds of changes are extremely preliminary, we don't have any good data at this point. :-?

[PeriscopeDepth]

Links!

Fish finding sonar:
http://www.humminbird.com/generic.asp?ID=407

More fish finding sonar:
http://www.eaglegps.com/Support/Tutorials/Sonar/coneangles.htm

Related subsim thread:
http://www.subsim.com/phpBB/viewtopic.php?p=274313&highlight=&sid=bd135438e02bd046ece11b499b3324ae

This is probably the best if you have the background to understand it:
http://casa.colorado.edu/~danforth/science/sonar/sonar1.html

Canadian sonar stuff:
http://jproc.ca/sari/asd_mod.html

Wikipedia:
http://en.wikipedia.org/wiki/Sonar

[LuftWolf]

Going back to our active sonar, if you look down on the ocean surface, then the zone of detection (the "ensonified" area around the ship) forms a solid circle centered on the ship with a notch cut out behind the ship since the propellers and engines mask the sonar returns.

Well, there we have it from the Canadian Sonar Link.

Thanks A LOT PD! :up: :sunny:

I'm sure it's not the "final word", but a "notch" sounds like about 60 degrees to me... :hmm: WOOT SCS! :-j ;)

[SeaQueen]

[This is primarily a free response poll]

Amizaur and I are wondering if the current cones of the active sonar systems are too wide in terms of realistic parameters, 300 degrees from the front of the ship, leaving only a 60 degree baffle for the active sonar at the rear.

This makes stalking convoys and escorts very difficult and if it were strictly a gameplay decision, we would reduce it. However, we want to check this against real world data.

I've never really worried about it. As I said in another thread, different sonars have different modes of operation, each with it's own beam pattern. If you REALLY wanted to get deep into this stuff, you'd have to get some very specific data (which would almost certainly be classified), and also change some of the sonar controls in the sim. You'd also have to worry about which direction you've pointed your sonar beam, because you can point a lot of sonars in different directions. It'd also vary by sonar type and other things. Is it a cylindrical array or a spherical array? There's only so much detail that's useful and I'm not sure this is the way to go.

As it stands, I think what we have is fine. The essentials are there. Here's why:

A submarine approaching a convoy is probably limited in his approach options less by the sensor coverage of the opposing forces and more by kinematics. If the submarine is outside of the limiting lines of a approach for the convoy (the width of which are dictated by a combination of the maximum silent speed of the submarine, and the convoy's speed of advance), then it doesn't matter that all the convoy's active sonars are pointing forward, because in order for the sub to get close enough to shoot a torpedo, he's going to have to go so fast that he'd be easy to pick up on passive sonar. A fast moving convoy can't be approached from the side or rear by a submarine moving silently.

Depending on the environmental conditions, the formation of the screening combattants, and the target type, there might be big holes in the convoy's sonar screen. So, for a submarine located somewhere in front of the convoy, it's up to him to guess how far the screens can see in that environment (maybe only two miles in a bottom limited case.. maybe ten.. in a surface duct or bottom limited with bottom bounce... maybe 30 in a CZ who can say?) and if they can cover the full arc in front of the unit they're screening. Based on that, he might decide the best thing to do is snap some photos and slink away, waiting for more heavily armed and survivable forces (surface combattants and aircraft) to attack the convoy. In this case, the submarine functions less as a silent stalker and more a silent scout for the fleet.

If the surface commander puts the screens too close, then YEAH the submarine is going to be detected if he approaches WAY close, but he might not have to in order to shoot a torpedo. Similarly, if the screens are too far out, for the range they can see, there might be big holes. Regardless, they still might not have enough time to launch a helo and get a shot off at the sub. If they're closing at 20 kts, then the whole scenario is going to play out really fast.

So... ya know.. it's a competitive process, and there's a lot of unknowns. It's actually a really difficult problem from both sides. That's the important thing. I don't see that the game would benefit a whole lot from worrying about the beam patterns of individual sonars. There's probably other things that would be more important to look at, if we're super concerned with realism.

One should not envision submarines as these invulnerable platforms capable of attacking any target in any conditions. That's not realistic. Against a fast-moving convoy, a submarine is basically an intelligent mine. The submarine, concerned with hiding, has to stay relatively slow, so the convoy has to almost run over him. The geometry dictating where the holes in the sonar screen are, comes from this fact, and the environment. The beam patterns have a relatively small impact.

Just my two cents...

[Fish]

Links!

Fish finding sonar:
http://www.humminbird.com/generic.asp?ID=407

More fish finding sonar:
http://www.eaglegps.com/Support/Tutorials/Sonar/coneangles.htm

Related subsim thread:
http://www.subsim.com/phpBB/viewtopic.php?p=274313&highlight=&sid=bd135438e02bd046ece11b499b3324ae

This is probably the best if you have the background to understand it:
http://casa.colorado.edu/~danforth/science/sonar/sonar1.html

Canadian sonar stuff:
http://jproc.ca/sari/asd_mod.html

Wikipedia:
http://en.wikipedia.org/wiki/Sonar

Your looking for me? :hmm: :up: