Stealth technology

[sav112]

Watched a program on one of the documentary channels and they were investigating the disappearance and finding and diving on U480. It seems it was invisible to sonar and only sunk because the brits had laid a trap of mines in the channel.

I know it’s later in the War being end of 1944-45 but I did not realise these U-boats had this Rubber coating with various small holes that trapped the frequencies. Stealth technology


I take it this would be totally out of the game if you made it to 1945, I remember playing SH III on some Dx sub I'm sure it was and it was more or less like this and very fast.

Having missed SH IV I’m looking forward to this new game.

[karamazovnew]

http://www.uboataces.com/sonar-coating.shtml

(viii) Counter-measures against British Asdics
The Petty Officer Telegraphist stated that tests had been carried out on a U-Boat with a rubber coating over the whole boat, the rubber being stated to have been 1/2 inch thick. These tests had not proved successful, as the rubber covering had considerably decreased the speed of the boat.

taken from http://www.uboatarchive.net/U-574INT.htm

Also: http://www.history.navy.mil/branches/org12-5.htm

Since some types of Hydrophones, radars and why not, the Walter boats were all experimental and played little part in the overall battle, you might expect the devs to omit them. But they add a nice touch to the game and let's face it, we've all started a 39 campaign with the Type XXI at least once just to see "how it could've been".

[mookiemookie]

The Alberich and Tarnmatte rubber coatings were indeed an upgrade in SH3. As I recall, each would reduce your sonar signature by 10%.

[sav112]

Unfortunately the crew were all but lost on this U-480 except for one that missed the outing due to him having bad feelings about a Woman that had been shown round the sub while back in base, The commander had given him the option to stay behind for training and saved his life.

It was his insight I found really interesting as he had said they had sunk four targets in the English channel and all hell had broke lose and they counted eighty-nine depth charges and only one was close and that was just luck. The coating was working 100% they could not be found.

Hope you get options to upgrade and have to fight to save your boat, I hated that Death screen you got in SHIII although I appreciate some times it would have been quick.

[karamazovnew]

Having 100% sonar dispersion would be cheating. But I agree that 20% wasn't much in SH3 . Anyway, it's not like you become invisible to sonar. At close range they can still pick you up but very imprecise. And since they don't know where you are, they might mistake those small pongs for a very far away sub. Pings sent by one escort can even be received by another escort so imagine their confusion. And as soon as you reduce your profile by turning away from the hunters and put a bit of space, then you become invisible.

[sav112]

To me that was always the Joy of SH games, the attack then the ever so slowly creep away from the pursuers. I really can emit I never really enjoyed the Torpedo hits so much as the fight to escape that Destroyer that has it in for you.

Although I never had confidence in the Ai, always felt that the destroyer was cheating a bit.

Agreed. It's trying to escape or evade an ASW ship that knows his stuff, that makes SHIII exciting. I only see torpedo hits during surface attacks. For submerged attacks, I'll listen if curcumstances allow.

[Platapus]

Alberich - which used a synethic rubber compound called Oppanol, Oppanol pannels were glued to the sides of the submarine as a way of both hindering active sonar by absorbing the active sonar pulses and reducing the sound signature of the submarine against passive hydrophones.

It was first used operationally (1940) on the U-67 Type IXC. The problem with Alberich was in the adhesive used. Gluing synethic rubber to steel alloys under water that can withstand the current effects as well as the temperature effects is difficult. Many experments showed that the tiles would strip away.

By 1944, improvements in adhesives were implemented on the U-480 Type VII successfully. Testing during the war and after showed that the Alberich tiles only reduced the active sonar signal (by absorbtion and redirection) by about 15%. Nice, but ultimately probably not worth the effort and expense.

http://www.uboataces.com/sonar-coating.shtml

[NZsnowman]

I am do a drawing U-1308 which had Alberich, here a drawing of the Schorchel head, with and without Tarnmatte


Also you are see real pictures of Alberich from U-480

[Edwin]

Testing during the war and after showed that the Alberich tiles only reduced the active sonar signal (by absorbtion and redirection) by about 15%. Nice, but ultimately probably not worth the effort and expense.

I've always wondered why the 15% percent figure keeps getting quoted as there's no real source behind it. The German tests came up as follows (from Cold War, Hot Science Applied):

"Meyer and Oberst had undertaken theoretical, laboratory and full-sized trials to develop a coating that could be applied to U-boat hulls which would reduce the reflectivity of the hull to impinging sonar pulses. Their experiments demonstrated that the parameters of concern were the thickness of the hull plating and whether air or water was behind it. On this basis they developed a two-ply rubber sheet 4 mm thick, with the inner ply perforated by 2- and 5-mm holes which determined the resonant nature of the system. Although the theory proved useful, the material was developed in an empirical fashion involving the testing of some tens of thousands of different materials. Trials were carried out with a full-sized U-boat in the Skagerrak late in the war which seemed to show the efficacy of the system, with a claimed reduction in reflectivity of 20 per cent. As this was accompanied by a reduction in detection range of 60 per cent, these claims were treated sceptically by the report's translators."

60 percent is certainly a dramatic and worthwhile reduction IMO (even if it only applies to certain depths or acoustic conditions)

[mookiemookie]

Originally Posted by Edwin

I've always wondered why the 15% percent figure keeps getting quoted as there's no real source behind it. The German tests came up as follows (from Cold War, Hot Science Applied):

"Meyer and Oberst had undertaken theoretical, laboratory and full-sized trials to develop a coating that could be applied to U-boat hulls which would reduce the reflectivity of the hull to impinging sonar pulses. Their experiments demonstrated that the parameters of concern were the thickness of the hull plating and whether air or water was behind it. On this basis they developed a two-ply rubber sheet 4 mm thick, with the inner ply perforated by 2- and 5-mm holes which determined the resonant nature of the system. Although the theory proved useful, the material was developed in an empirical fashion involving the testing of some tens of thousands of different materials. Trials were carried out with a full-sized U-boat in the Skagerrak late in the war which seemed to show the efficacy of the system, with a claimed reduction in reflectivity of 20 per cent. As this was accompanied by a reduction in detection range of 60 per cent, these claims were treated sceptically by the report's translators."

60 percent is certainly a dramatic and worthwhile reduction IMO (even if it only applies to certain depths or acoustic conditions)

But from what I've read about the system is that the adhesive was flawed. Once the rubber coating was applied, the boat would submerge and the adhesive would fail in places, causing the rubber tiles to flap in the current, actually increasing the noise signature of the boat. This is why the idea was good in theory but flawed in practice.

[Kaleun_Endrass]

Originally Posted by mookiemookie

But from what I've read about the system is that the adhesive was flawed. Once the rubber coating was applied, the boat would submerge and the adhesive would fail in places, causing the rubber tiles to flap in the current, actually increasing the noise signature of the boat. This is why the idea was good in theory but flawed in practice.

I read somewhere that this was the reason why the first coating tested in early 1940 was withdrawn and and second approch to introduce a rubber coating was made in late 1944.

[java`s revenge]

I think that the modders of the great mod gwx3 has looked too much to das boot.

Nowadays a uboat is still difficult to track. I do remember an incident nearby the swedish coast. The swedish navy was searching for a russian sub but it was
never been tracked.

You can`t tell me that as in gwx3 that you were so easily to be found by
destroyers.

1 point, laying on the seabed with your sub. In real life you were unfindable.
You know what happens when you try it in sh3.

[sav112]

All I can say to on the subject of the resin to attach the Coating was that in the TV programme they discussed that U480 had to go in to get it repaired when the Captain bottomed the boat and it moved across the seabed under Ocean currents.

But the guy who survived said the boat Coating was strong after they got there act together in first blasting the hull in dry-dock with metal ball Barings to give a an ultra smooth and clean surface then painted with bonding coat.

But I’ll tell what that was crystal clear that when they dived on the boat the Coating was fantastically intact after being on the sea bed for over 60 years.