RA mod 1.41 with Patch #1 and #2

[jaop99]

I have the latest RA mod 1.41 with both Patchs.

I was playing in an Akula vs an Oscar II and looks like he detected me and launched two Shkval torpedoes, because the where "flying" at 189 knots underwater, ok, no ping from them only a lot of noise, but both torpedoes exploded more than 200 yards from my sub and they crippled me, unless the torpedoes were carrying a nuclear warhead, the standard 210kg warhead should not damage my sub from this distance, any idea? (post video below)

https://www.youtube.com/watch?v=NjW0abwl7Ac

[ikalugin]

If Shkvals were not pinging you they were nuclear.

[FPSchazly]

I did a back-of-the-envelope calculation of this at one point, and yes, 210 kg of conventional warhead at that distance shouldn't really do any damage to you. It seems they do model the damage from Shkvals at nuclear energy levels.

[p7p8]

Shkval have only MAD sensor - it not pinging.

On map you have positon center of your sub, so second shkval almost hit you directly.

For distance measuring (and bearing) press "r" on map. Works also in replay window.

BTW vanilla campaign is not compatibile with RA

[p7p8]

I did a back-of-the-envelope calculation of this at one point, and yes, 210 kg of conventional warhead at that distance shouldn't really do any damage to you.

Can you describe methodology of your calculations?

[jaop99]

Hi guys, my calculation method is very simple, in the replay map there is a scale in the bottom left corner, the scale was 500 yards, then both torpedoes exploded about the 200 yards far, period!, thats why I'm asking if the Oscar II had nuclear warheads in any of the vanilla missions. The second torpedoe exploded about 150-180 yards, a 210kg warhead is not enough to do anything to a big sub from this distance!.

[p7p8]

I asked about calculations for those:
210kg warhead is not enough to do anything to a big sub from this distance!
and
210 kg of conventional warhead at that distance shouldn't really do any damage to you

I think DW have very simple model of damages (you can still run with 99%). Your sub had only 45% of damage - it means many systems needed a lot of time to repair.

Your sub had course 010 deg. and shkval exploded near 175 deg from center of your sub. Akula III have aprox. 123 yd of lenght, so you should subtract 60 yds from first measurement (200 yds)

I think it is close enough for damaging of some systems.

BTW: For accurate range measurement you can use "r" key on map.

[jaop99]

Take any calculation of a bigger airborne warhead IRL, for example FAB-250 or RBK-250, in the air where there is not almost no density, the shrapnel can reach about 400+ meters away, but the blast and expansive wave's real damage is about the range of 200-300 yards. Now, any explosion in the water, is more difficult to reach farest targets due the density of the water, and the pressure depending the depth where the bomb exploded.

In WWII the depth charges had from 400-3000 pounds (400 pounds were the used in mortars) but even with this payload, the explosion should be close to the sub to make a real damage.

http://www.engr.psu.edu/cde/Short/MPS_course/newpage/Exp-Dam-Ass-1.pdf

[jaop99]

I asked about calculations for those:

and


I think DW have very simple model of damages (you can still run with 99%). Your sub had only 45% of damage - it means many systems needed a lot of time to repair.

Your sub had course 010 deg. and shkval exploded near 175 deg from center of your sub. Akula III have aprox. 123 yd of lenght, so you should subtract 60 yds from first measurement (200 yds)

I think it is close enough for damaging of some systems.

BTW: For accurate range measurement you can use "r" key on map.

Yeah I agree it could take damage, but in the game they were massive!, I think that Crazy Ivan changed something in the damage model of the Shkval from the previous version.

[FPSchazly]

Can you describe methodology of your calculations?

My methodology is very simple. Let me start by saying I know nothing specific about how explosions work, but I was intrigued by this passage on a Wikipedia article on depth charges:

The killing radius of a depth charge depends on the depth of detonation, the proximity of detonation to the submarine, the payload of the depth charge and the size and strength of the submarine hull. A depth charge of approximately 100 kg of TNT (400 MJ) would normally have a killing radius (hull breach) of only 3–4 meters (10–13 ft) against a conventional 1000-ton submarine, while the disablement radius (where the submarine is not sunk but put out of commission) would be approximately 8–10 meters (26–33 ft). A larger payload increases the radius only relatively little because the effect of an underwater explosion decreases as the cube of the distance to the target.

Using this information, I used an equivalence to determine the kill and disablement ranges for a 5 kt nuclear warhead. 100 kg of TNT ~ 0.1 ton.

0.1 ton / (3 meters)^3 = 5000 / (X meters)^3

(I'm basically saying 0.1 ton divided by 3m^3 is equivalent to "kill", so I set 5000 ton / X meters ^3 equal to that and solving for X. This is nothing more than a simple extrapolation.)

Solving for X produces a killing range of approximately 110 - 150 m and a disablement range of approximately 300 - 370 m.

Let's discuss my assumptions. I'm assuming a large nuclear sub (~7000-10000 t displacement) behaves similarly to a 1000 t conventional sub in response to explosive damage. This is probably not a good assumption, as smaller objects tend to be stronger than larger objects due to the square-cube law; however, the larger nuclear submarines also have more mass to absorb explosion energy. I am not sure which would be the dominant effect.

These numbers on Wikipedia also have no citation, so I'm not sure where these kill and disablement ranges come from. However, assuming the numbers are correct, I was just curious to see what the numbers would be assuming a nuclear-sized warhead and extrapolating using a simple method. It's an interesting result, it's not one I would expect, and suggests more investigation.

That Wikipedia article also discusses more effects, such as primary and secondary shockwaves, the depth of the explosion, explosion shockwave reflections off the bottom of the ocean, and other things that are not considered in my simple calculation.

Yeah I agree it could take damage, but in the game they were massive!, I think that Crazy Ivan changed something in the damage model of the Shkval from the previous version.

Based on my experience in vanilla and RA, the Shkvals are about equal in damage in both versions. I haven't seen anything to suggest the RA Shkvals are more damaging.

[jaop99]

I agree with you, if the Oscar used nuke torpedoes, the damage I received is fair!, and I remarked this from my first post! :Kaleun_Salute: and by the way, most of the russians subs have double hull with materials that were a dream in the WWII.

Wiki about Akula:

"The Akula incorporates a double hull system composed of an inner pressure hull and an outer "light" hull. This allows more freedom in the design of the exterior hull shape, resulting in a submarine with more reserve buoyancy than its western analogs. This design requires more power than single-hull submarines[citation needed] because of the greater wetted surface area, which increases drag."

[p7p8]

Thx for explanation Chazly :Kaleun_Salute:
Yeah I agree it could take damage, but in the game they were massive!
45% of damages are not "massive". Like I said before, in DW 99% of damages allows you play well after repairing (1-2.5 hours). I think 100% of damages means that your sub is not controlable anymore ...and from that moment is sinking. This is something different than "completly destroyed".

BTW double hull is not inner hull + external "armor".

[FPSchazly]

Thx for explanation Chazly :Kaleun_Salute:

You're welcome! :Kaleun_Cheers:

BTW double hull is not inner hull + external "armor".

Yes, the internal hull is the pressure-bearing hull. The outer hull is for hydrodynamics, and also forms the outer boundary of the ballast tanks.

[ikalugin]

The increased strength of the hull structures and the boyancy reserves typical for Soivet desighns (not all of them, but such reserves were standard) improve survivability.

For example if a single compartment is flooded on LA class you are dead, if a single compartment is flooded on Akula you may still have a chance.

[p7p8]

Yeah, Russian/Soviet nuclear submarines are much more stronger and safer than american subs but they just have "bad luck"

sunken nuclear submarines (https://en.wikipedia.org/wiki/List_of_sunken_nuclear_submarines)

[ikalugin]

Yeah, Russian/Soviet nuclear submarines are much more stronger and safer than american subs but they just have "bad luck"

sunken nuclear submarines (https://en.wikipedia.org/wiki/List_of_sunken_nuclear_submarines)
How many of those losses were due to a hit by a lightweight torpedo?

If they were not due to the combat dammage or simmilar dammage incured, then how is it relevant?

[p7p8]

I doesent matter because subs sunken by LwT = ZERO

But submarines with:
(...)strength of the hull structures and the boyancy reserves typical for Soivet desighns (...)
...should not be a leader in infamous list of sunken one.


In quantities of accidents where sub was not sunk finnaly, they have also "first place" - it is sad truth.


I am big fan of soviet submarines but i think "boyancy reserve" was repercussion of huge numbers of accidents (in comparsion to "west" subs). In other hand stronger structure was necessary because they operate close to polar region.

[ikalugin]

Ok, let me explain. The only example on your list between two countries where the sub was lost due to a combat-hit-like cause was Kursk. Others Soviet/Russian were due to other reasons, not related to the torpedo hit survivability, ie


1/7 lost due to scutling.
3/7 lost during towing.
1/7 lost due to flooding (but as I note below Charlie series did not have boyancy reserves).
1/7 due to flooding (after a fire, so not relevant to this specific scenario)

The US losses on the other hand were both due to their hull weakness, which may be viewed as relevant in this context.

Kursk had an internal detonation of a carrier-killer 650mm torpedo, which lead to flooding of 3 compartments. Soviet desighn standard (with exceptions that did not follow it) states that submarine must maintain positive boyancy with single compartment flooding, this is where boyancy reserves come from (the submarine desighns that did not follow that standard may have less boyancy reserves - Charlie series or more reserves - Typhoon class).

That desighn standard implies that if hit by a lightweight torpedo that would flood one compartment would allow a Soviet patern submarine (with exceptions) survive while would lead to a certain death of a USN patern submarine.

p.s. the reason why Charlie (Charlie-I and Charlie-II) series of SSGNs were not desighned with standard reserves (speed/dive depth or any number of other things viewed as standard in Soviet practice at the time) was due to the desire to build those submarines at an inland shipyard. Sierra series SSNs (Sierra-I, Sierra-II, Sierra-III) managed to get their standard reserves via extensive use of titanium and other displacement saving measures.

[jaop99]

I managed to complete the mission yesterday, with this new ROE in mind after install RA mod 1.41, of enemy subs using Shkval torpedoes with nuke warheads. I will edit the mission and upload it tonight or maybe tomorrow!, but was a tense situation, evading not only the Shkvals, but multiple STALLIONS or Sizzler ASW launched from the surface vessels!

The best way to evade the Shkval: launch an active decoy and run at flank speed far from the possible detonation area (I could evade four in this way, exploding near the decoys, because was the only object they found with their MAD!), and at the same time I sank an Oscar and a Victor subs with a mixed combination of one Shkval and one USGT for each one, the first crippled many of their systems, and the second was the shot of grace.

What really saved me, was the use of voice commands and not the keyboard to give orders.

[p7p8]

All countries (Russia, USA, UK) had nuclear submarines accidents but most loses were on russian/soviet side. I don't care about reasons.

If russians subs have that high standards for survivability, why they have much more loses than any other country?

That desighn standard implies that if hit by a lightweight torpedo that would flood one compartment would allow a Soviet patern submarine (with exceptions) survive while would lead to a certain death of a USN patern submarine
I think that is still dangerous because flooded compartment is not equal "destroyed" compartment. And why you are so sure that LWT can destroy only one compartment?

Kursk was one of the biggest sub in the world with greatest bouyancy reserve and theoretically should survive that explossion. The main problem is word "therotically".

In this topic main problem is 45% of damages on Akula III class from explosion of 210 kg from 120-180 yds. Because in DW you can still run your sub with 99% damages i think this is NOT overall "health". In my opinion 100% of damages means "bouyancy reserve" is exceeded (no matter how many compartments are flooded) and you can't longer control your boat.

in mind after install RA mod 1.41, of enemy subs using Shkval torpedoes with nuke warheads
I think it is not true. Nuke warhead would be much more destructive to your Akula III from 120-180 yds. 45% of damage is not "massive".

[ikalugin]

Because those losses were due to non-combat like causes (scuttling during decomission, loss turing towing etc) they are irrelevant to the discussion of combat survivability.
You can make an argument regarding reliability and safety of the Soviet designs, but it is again irrelevant to this specific discussion.

Because with double hull and high strength pressure hull it is unlikelly that a hit by a lightweight torpedo would lead to flooding in multiple compartments. If anything Kursk shows that in order to achieve flooding of multiple compartments you need a very big explosion.

Technically no, Typhoons are both larger and have larger reserves. Kursk sank due to internal (and thus more dammaging) explosion of multiple 650mm torpedos which are by far more potent than a lightweight torpedo or even the classical heavyweight torpedoes.
Thus even that case is not illustrative of the expected combat survivability.

[p7p8]

Because those losses were due to non-combat like causes (scuttling during decomission, loss turing towing etc) they are irrelevant to the discussion of combat survivability.
Why you think that. Is russian/soviet subs have greater buoyancy only during combat?
USN/UK subs have same "low" buoyancy reserve all the time. Statistically they should be sunken in accidents more often than russian subs.

[ikalugin]

Why you think that. Is russian/soviet subs have greater buoyancy only during combat?
USN/UK subs have same "low" buoyancy reserve all the time. Statistically they should be sunken in accidents more often than russian subs.
That is a faulty assesment, because if you look at the losses of the subs they were due to the causes that were independent from boyancy reserves where those were availiable (ie excluding charlie class for example).

In fact in one such case (loss of the Mike class) the loss can be attributed to a feature that improves survivability to combat dammage (solid fuel gas generators for emergency blow), that feature is currently standard on Soviet/Russian desighns.

To recap my point - double hull and boyancy reserves allow the submarine to survive certain types of combat dammage (lightweight torpedo hit with a single compartment flooding) unlike the classical single hull, poorly compartmentalised US desighns without reserves, but does not magically make that sub unsinkable (though Oscars and Typhoons are as close to that as possible).
Nor does it affect the reliability and safety of the desighn, which is a separate matter entirely.

[jaop99]

I think it is not true. Nuke warhead would be much more destructive to your Akula III from 120-180 yds. 45% of damage is not "massive".

Simple maths, ot they are nukes or they cant damage my boat at all with a 210kg conventional warhead explotion at 120-180 yds. Period. Have you read any of the posts about the damage of the depth charges in the WWII in this thread?.

Citing Wikipedia:

"Although the explosions of the standard United States 600 lb (270 kg) Mark 4 and Mark 7 depth charge used in World War II were nerve-wracking to the target, an U-boat’s undamaged pressure hull would not rupture unless the charge detonated closer than about 15 ft (4.6 m). Placing the weapon within this range was entirely a matter of chance and quite unlikely as the target maneuvered evasively during the attack. Most U-boats sunk by depth charges were destroyed by damage accumulated from a long barrage rather than by a single charge. Many survived hundreds of depth charges over a period of many hours; U-427 survived 678 depth charges fired against it in April 1945."

https://www.reddit.com/r/AskHistorians/comments/5tg03u/how_effective_were_depth_charges_in_wwii/

[p7p8]

Here is link to interesting document - link (http://www.amw.gdynia.pl/library/File/ZeszytyNaukowe/2015/ZN%20AMW_2015_2/Szturomski.pdf)

and here are some graphics:

http://i.imgur.com/H7tLTaU.jpg

Descriptions about pressure:

http://i.imgur.com/MOrDlIf.jpg?1
http://i.imgur.com/RQoIX6z.jpg?2

Document and graphics are about "Underwater explosion on a ship" - not submarine but i think it gives us some good reference.

It shows that 210 kg of TNT can't sink ship from distance 120-180 yds. In other hand, your damages was not massive. I think they responds 2-6 MPa.

I can't find information how strong nuclear warhead had shkval, but i think nuke explosion from that distances should sink your sub immediatly.

Conclusions:

- In RA shkval does little too powerfull damages from distances 120-180 yards but i think it is acceptable for "game purposes".
- damages you took definitely was not from nuke warhead

[FPSchazly]

Document and graphics are about "Underwater explosion on a ship" - not submarine but i think it gives us some good reference.

It shows that 210 kg of TNT can't sink ship from distance 120-180 yds. In other hand, your damages was not massive. I think they responds 2-6 MPa.

I can't find information how strong nuclear warhead had shkval, but i think nuke explosion from that distances should sink your sub immediatly.

Conclusions:

- In RA shkval does little too powerfull damages from distances 120-180 yards but i think it is acceptable for "game purposes".
- damages you took definitely was not from nuke warhead

I agree that a nuke at that distance would result in immediate sinking. I also agree with both of your conclusions. The Skhval's current explosion would be consistent with a rather small nuke (<0.1 kiloton), but I feel the Shkval would have a much larger nuke (or at least it could) because it is a rather large torpedo. It seems likely Sonalysts modeled Shkvals this way for gameplay purposes, which I'm fine with.

EDIT: By the way, the stuff you posted is very cool :up:

[jaop99]

I do not agree, we are talking of a WAR VESSEL!. Are a superb charts, but looking the distance and payload, the category falls to 2-4 (for a 300 kg payload, the Shkval only have 210Kg), for a ship is lighting lamps cracking and electronics, but THIS IS AN AKULA (Project 971), in the scale of less than 4 MPa it should not receive any damage at all, only a simple push. And by the way, the voices only reflected a small part of the damage I received, in fact the damage screen in the first test was complete full of red text, will repeit the test. If my radio antenna, radar and all the electronics broken were deployed is ok, but they were secured inside the sub tower.

[p7p8]

In DW damages are completly random. I am sure with 45% most of them needs about 1 hour (max) for repair.

but THIS IS AN AKULA
Sorry for joke but i cannot resist :)

...but:
http://i.imgur.com/Un1Wtxp.jpg?2

Yes, this is Akula, so?

we are talking of a WAR VESSEL

Yes, I know that. Did you look to linked document?

Civilian vessels are safe with pressure 0-0,4 MPa
Warship are safe with pressure 0-2 MPa
(this is on second picture)

All time you said "damages was massive" but on YT you did not check list of damages and how many minutes takes repairing. You just quit mission!

From my experience i know that 45% of damages is not too much. Probably your submarine still was able to gain max speed, depth etc.

[jaop99]

:haha: GREAT PIC!, but yes the Akula is something similar to Sparta in the sub world! :Kaleun_Cheers: and yes, I read the whole document is great!

[ikalugin]

2 MPa is ~ 20 atm or ~ pressure at 200m depth.

Ofc there is a difference between static and dynamic loads, but on low depths such a change in pressure that doesnt sound as all that lethal considering the crash dive depth of the desighn.

Morever, more or less post Alfa class the Soviet SSN/SSGN desighns were optimised (in terms of hydrodynamic shaping and structural desighn) to improve survivability against (nuclear) depth charges.

[FPSchazly]

Ofc there is a difference between static and dynamic loads

That is the key right there. :up: In the case of a localized explosion, such as a depth charge or conventional torpedo, as the shockwave moves, one part of the sub will be seeing this transient increase in pressure while another part will not. That pressure gradient is what creates damage.