Full stop sonar signature with LWAMI 3.08
 

What is the sonar signature of a completely stopping vessel like in LWAMI 3.08? As a vessel is at full stop they don't emit screw noise hence making the vessel stealthier than it is at 3 knots.

Is it possible to reduce the sonar signatre significantly at full stop with LWAMI. Or is this already done. I know that at full stop some machinery onboard are still operating like the electric generator, etc. but the engine sound signature should disappear altogether imo. No more engine harmonics. Luftwolf i'm asking this because with your realistic mod i have a very hard time successfully completing the first stock campaign mission. Perhpas a full stop would better hide my vessel/boat. Besides this was what made Sub command loses some relism point in gameplay. And i got the feelin that this persists even after DW.:damn:

Not much can be done to customize SL's at specific speeds. Since the hotfix, we've been able to set a base SL and a fixed rate of increase. That's it.

A lot of what you are asking here is dependant on the type of sub involved. A diesel/electric will be essentially a hole in the water when the boat is not moving. You might have some fan noises and such but as far as propulsion related sounds, well.. they become essentially non-existant.

A nuclear powered boat on the other hand will ALWAYS have a base noise level regardless of how slow you spin the screw. This is due to how the propulsion plant operates. The trick answer here is at what speed does the noise level increase?

I wish we COULD control more aspects of the sonar model and baselines for noise levels. Then we could REALLY have some fun with folks as what does not change is the ability to be detected by an increase in speed but rather the ability of the sub to detect OTHER subs due to degregation of sonar capability as speed increases.

So why not set the base sound signature at 0-zero db(nonexistent) for diesel subs as now we know that diesel subs don't emit sound signature at full stop.

So from the game perspective the nuclear subs are already realistically(pretty much) modelled regarding their noise(sound signature) level. Guess the nuclear generator is still at work all the time.

Though this doesn't help with winning the first stock campaign mission.

EDIT: What about ships. With the exception of those ships with nuclear propulsion, any other ships would not emit sound signature during a full stop right?(I mean engine sound signature). Too bad there's only fixed noise increment implemented for each(or is that every/shared noise increment:dead:) vessel in game. Otherwise we could play on the numbers beacuse every sub is optimized for specific speed range only imho. Above that noise increment would increase subtantially:88).

Because then the SL's for every speed other than 0 would make no sense. As it stands now, the SL's are about as good as they can get for the Kilos. Eariler in the week, I randomly found some information about comparative SL's...I immediately grabbed the LW/Ami SL chart to see if something needed changing, but sure enough, the chart lined up with what the reported real-world result was supposed to be. Getting 0 right (assuming it's right) isn't worth losing that.

Actually, this assumption is incorrect. Most of the systems still actually turn, even at Full Stop. On a ship, the boilers, reactors and turbines still work, because they have to turn the turbo-alternators to produce electrical power. There is an emergency diesel generator somewhere, but you tend to only start that up if the main generators that are tied to the main engines fail, and since those are emergency toys, they are probably not made for silence, just for being as small and unobtrusive while providing minimal capabilities as possible.

Even the screw often rotates at a slow speed. Some designs actually leak if the shaft is completely stopped (in port there's a stopper you put around the shaft seals). At slow speeds, a well-designed screw should be very quiet and make only an incremental increase over no rotation, not a well-defined jump.

Further, in real life, AFAIK most subs and ships like to maintain at least one or two knots (steerageway) so that they can determine their course in the face of currents underwater. We like to Full Stop, but that's actually a wee-bit unrealistic in realistic conditions.

That's not to say I won't want a more dynamic noise increase model. It can model a nuke sub's nat-circ going to main circulation and all that. Several extra noise coefficients could fix that. But I wouldn't waste one of them trying to model the difference b/w 0 and 1 knot.

LOL.. yet another of my pet peeves that I feed on a regular basis.

OHP is a GREAT case. It is powered by gas turbines with a varaible bladed prop.

The gas turbine has a minimum rotational speed that it MUST maintain in order for the turbine to stay 'lit off'. This means the screw is ALWAYS turning, even at all stop. Now, here is where the variable pitch comes in. You neutral out the pitch and you have NO thrust vector. Meaning the thing is spinning but you ain't moving. As you start increasing the bell you are only increasing pitch till you max it out (being simple here folks) , THEN you are increasing the actual speed of the gas turbine to go any faster. What this means is that ships speed can increase without any increase in shaft RPM's. Where is this breakpoint from increasing pitch to increasing RPM's? Honestly I do not know.

Here is the kicker. You CAN decouple shaft speed from pitch in the game. Right click the throttle on the right side and you can move pitch independent of shaft (turbine) speed on the left side. With the left throttle quardrant at ahead full, I slammed the pitch in full reverse and guess what? The ship stops and then backs up.

I ran 2 machines here and performed a test. Guess what? It does not accurately model (at least from what I could tell) the fact that you can move these independantly. Imagine the hard time you can give a submariner in trying to get a solution on you. If he is relying on TPK from Demon...well you could make his life hard. He can hear you but how fast are you REALLY moving?

Well i agree on this. I was suggesting whether a modification to simulate full stop is viable without degrading the overall realism. Well everybody seems to be suggesting it's not or even if it's possible there's not much difference between a 1 knots or a full stop sound signature and as even at full stop the screws are still rotating hence giving out sound signature. Good to know that LWAMI noise level model is close to reality as what Molon Labe suggests. I'm obsessed with realism according to my therapist :rotfl:.

Here's the catch to this one:

The primary frequency for screw noises is in the single digit Hertz range with higher frequency harmonics. That low a frequency sonar is not modelled in DW, which starts at 50Hz. I suspect the reason for that is that at that point, your predominant sources of noise are geologic in origin and poor Sonalysts doesn't want to have to model the tectonic plates scraping against each other and underwater volcanoes too. :D

Well... ya know... one should take a simulation for what it is. It is a simulation, not real life, and it has limitations. Depending on the depth of the water, once you get into the tens of Hz range, the origins of your transmission loss may be totally different from in the hundreds or thousands of Hz bands. The DEMON display is trying to capture of some the idea of blade rate and it does an adequate job I think. The thing is, if you wanted to really get down into the single Hz range and actually be accurate, you'd probably have to rewrite the sonar model for DW. It's not so simple as a database change.

My wish list:

1) Non-linear or multi-point curves for PSL vs. Speed. :damn:

Cheers,
David

Last time I checked, the blade rate on a demon display was essentially finding the current turn speed value by doing speed/tpk. Doing a full stop would kill the demon signature immediately* instead of gradually compacting to the left. And when that is so, never mind the variable tpk you should be able to achieve in the ohp...

* since the DW simulation of demon is 'no minimum rotation speed' - another thing that should be added to the thrust db if they decide to add it.

I believe these values are, like masts, not transmitted to other players in a multiplayer session in the first place, but even if they were, they probably wouldn't be used for it as DW is now.

Well... apparently, nukes HAVE to keep their props spinning at some rate to maintain the seal between the shaft and the hull, which means this is only really an issue with diesels, and diesels tend to be quiet enough that DEMON data is pretty hard to come by.

You are correct and this should be modelled in DW, however, it's not really a huge deal as things stand now.

Cheers,
David