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Acoustic torpedo

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Hello everybody,


in World of Warships has been always discusion about submarines and if it is possible for submarines to be in this game.
With the Halloween event Terror of the Deep in 2018, there has been opinion that this fun mode is just a test.
This was confirmed 2 days ago on Gamescom 2019. Wargaming is planning to create German and US Submarine tech tree branch for WoWs.
They showed us early-stage gameplay of submarines and DDs against each other.
In these gameplays, after torpedo from submarine is fired, you can try to mark the ships bow or stern, so the torpedo can become homing torpedo.

I have been reading forum for 2 days and many people are concerned about homing torpedoes in this gameplay (and rightfully so).
So let's take a closer look at these homing torpedoes to understand them more.


Torpedoes are the main source of damage for submarines, therefore if are homing torpedoes available for them or not is a huge thing for their success.


Please keep in mind that this article is ONLY about homing torpedoes, their history and possible implementation in game.
In this article, just after historical part, there will be few ideas of implementation of homing torpedoes in game.


This article IS NOT about: 
-submarines in game would be good/ bad
-Anti-submarine warfare
-balance of submarines and their implementation in game
Keep this in mind.


Also I apologize for any grammar mistakes, english is not my native tongue.

Acoustic torpedoes


Acoustic torpedoe is a torpedo that aims itself by listening for characteristic sounds of its target or by searching for it using sonar (acoustic homing).
Acoustic homing torpedoes are equipped with a pattern of acoustic transducers on the nose of the weapon.
By a process of phase delaying the signals from these transducers a series of "acoustic beams" (i.e. a variation of acoustic signal sensitivity 
dependent on the incident angle of the noise energy).
In early homing torpedoes the "beam patterns" were fixed whereas in more modern weapons the patterns were modifiable under 
on-board computer control. These sensor systems are capable of either detecting sound originating from the target itself i.e. engine and 
machinery noise, propellor cavitation, etc., known as passive sonar , or responding to noise energy reflections as a result of "illuminating" 
the target with sonar pulses, known as active sonar.


Acoustic torpedoes in World War II.

    The first passive acoustic torpedoes were developed nearly simultaneously by the United States Navy and the Germans during World War II. 
The Germans developed the G7e/T4 Falke, which was first deployed by the submarines U-603 , U-758 and U-221 in March 1943.
Few acoustic torpedoes were actually used and quickly phased out of service in favor of the T4's successor, the G7es T5 Zaunkönig torpedo 
in August 1943. The T5 first saw widespread use in September 1943 against North Atlantic escort vessels and merchant ships in convoys.
    The German U-boats now had an effective "fire and forget" weapon capable of homing-in on attacking escorts and merchant ships 
and doing so in close quarters of only three or four hundred yards. By summer of 1943, the German U-boat campaign was experiencing 
severe setbacks in the face of massive anti-submarine efforts integrating Coastal Command attacks in the Bay of Biscay, 
the deployment of merchant aircraft carriers in convoys, new anti-submarine technologies such as hedgehog and improved radar, 
and the use of dedicated hunter-killer escort groups.


    On the Allied side, the US Navy developed the Mark 24 mine, and was actually an aircraft launched, anti-submarine passive acoustic 
homing torpedo. The first production Mk. 24s were delivered to the U.S. Navy in March 1943, and it scored its first verified combat kills in May 1943. 
About 204 torpedoes were launched against submarine targets, with 37 Axis submarines being sunk and a further 18 damaged.



    The German T5 torpedoes were countered by Allied introduction of the Foxer noise maker. Foxer was the code name for a British built 
acoustic decoy used to confuse German acoustic homing torpedoes. A US version codenamed FXR was deployed at the end of September 1943 
on all transatlantic escort vessels but was soon replaced by the more effective Fanfare noisemaker.
    The device consisted of one or two noise-making devices towed several hundred metres astern of the ship.
The noise makers mechanically generated a far more louder cavitation noises than the ships propellers.
This noise distracted the acoustic torpedoes away from the rear of the ship into a circling pattern around the noise maker until the torpedo ran out of fuel.
The downside of the Foxer was that it also rendered the own ship's ASDIC ineffective and concealed any other U-boat nearby that could 
home in on the convoy. Nevertheless, the FXR countermeasure proved to be highly effective in decoying German acoustic torpedoes. 
Of the c. 700 fired G7es torpedoes about only 77 had found their aim.


Please keep in mind, that characteristics of acoustic torpedoes (speed,...) are historically accurate and will be (most likely) in game changed.


Mark 24 mine
    The Mark 24 mine (also known as FIDO or Fido) is an air-dropped anti-submarine warfare weapon (ASW) incorporating passive acoustic 
homing system and torpedo integration. It was used by the United States, the British and Canadian forces 
during the Second World War and entered service in March 1943 and remained in use with the US Navy until 1948.
The deceptive name of "Mark 24 Mine" was deliberately chosen for security purposes, to conceal the true nature of the weapon.


Designed: 1942

Number of acoustic torpedoes built: 4000
Length: 84 inches (213,36 cm) 
Diameter: 19 inches (48,26 cm)
Mass: 680 pounds (308,44 kg)

Effective firing range: 4000 yards (3,657 km)
Search duration: 10 minutes
Speed: 12 knots

Warhead weight: 92 pounds (41,73 kg)
Detonation mechanism: Mk 142 Fuse- contact exploder


Upon water entry, FIDO performed a circular search at a predetermined depth controlled by a bellows and pendulum system
(acoustic torpedo could change it's direction not only horizontally but also vertically).
This continued until the potential target's 24 kHz acoustic signal detected by the hydrophones exceeded a predetermined threshold level, 
at which point control was then shifted to the passive acoustic proportional homing system. 
Initially the torpedoes were set to search for a target at a depth of 50 feet (15 m), this was later changed to 150 feet (45 m).
To prevent the torpedo accidentally attacking surface ships, it resumed its circling search if it rose above a depth of 40 feet (12 m).
The torpedo's relatively low speed was kept secret because, although U-boats could not outrun the torpedo when submerged, 
they could outrun it on the surface.




Mark 27 torpedo
    The Mark 27 torpedo was the first of the United States Navy 19-inch (48-cm) submarine-launched torpedoes.
The torpedo employed a passive acoustic guidance system and was intended for both submarine and surface targets.
Nicknamed "Cutie" by submarine crews, the Mark 27 entered service in 1943 as a defensive weapon. 
The torpedo was classified as obsolete in the 1960s.

The Mark 27 was essentially a Mark 24 mine which had been modified for submarine launching in a 21-inch submerged torpedo tube 
by the addition of 1" wood guide studs mounted on the torpedo's outer shell.

The Mark 27 Mod 4 torpedo was designed by the Ordnance Research Laboratory of Pennsylvania State University in 1946 
as an improved version of the Mark 27 torpedo.Fully compatible with electrical setting fire control systems through the use of the standard 
65-pin umbilical cable, this weapon was in service on submarines for about ten years. 
It was withdrawn from service use in 1960 with the introduction of the Mark 37 torpedo.


Mark 27 torpedo characteristics:
Designed: 1943

Number of acoustic torpedoes built: 1000
Length: 90 inches (228,5 cm) 
Diameter: 19 inches (48,26 cm)
Mass: 720 pounds (326,586 kg)

Effective firing range: 5000 yards (4,572 km)
Search duration: 12 minutes
Speed: 12 knots

The Mark 27 Mod 4 torpedo characteristics:
Designed: 1946

Number of acoustic torpedoes built: 3000
Length: 125.75 inches (319,405 cm) 
Diameter: 19 inches (48,26 cm)
Mass: 1175 pounds (532.97 kg)

Effective firing range: 6200 yards (5,6693 km)
Search duration:  12 minutes
Speed: 15,9 knots

Warhead weight: 128 pounds (50,05 kg)
Detonation mechanism: Mk 11 Mod 2 - contact exploder



G7e/T4 Falke
    Early in 1933 Germany started development and testing of acoustic homing mechanisms for torpedoes.
With the introduction of Falke, U-boats could remain more deeply submerged and fire at convoys with nothing to give away 
their position but the noise of their screws. 
    Falke worked much like a normal straight-running torpedo for the first 400 m of its run, after which its acoustic sensors 
became active and searched for a target. The sensitive sound-sensing equipment in Falke required the torpedo be as quiet as possible, 
hence it ran at only 20 knots (37 km/h); in addition, the firing U-boat was forced to stop its motors. Falke was intended to home on merchant targets.
Only known to have been fired in action by three U-boats, U-221, U-603 and U-758.
    Although regarded as successful, Falke was rapidly phased out of service. It was replaced by the G7es/T5 "Zaunkönig" ,
which was faster and better able to home onto the sound of fast moving warships as well as merchant traffic.


G7e/T4 Falke torpedo characteristics:
Designed: about 1940

Length: 7.186 m
Diameter: 533 millimetres (21.0 in)

Effective firing range: 7500 m
Search duration: 12,16 minutes
Speed: 20 knots

Warhead weight: 440 lbs. (200 kg) Hexanite





G7es (T5) Zaunkönig
    When compared to G7e/T4 Falke, the Zaunkönig was faster, had more range, possessed a magnetic or contact detonator 
and could be equipped with a percussion pistol. The homing system consisted of two hydrophone receivers and altered the direction 
of the rudder via an electropneumatic device. The acoustic homing torpedo was specifically designed as to be attracted by the pitch of 
an escort's proppellors and would — even if aimed inaccurately — explode under the ship's stern.
    The acoustic homing torpedo required a minimum distance of 400 metres (1,300 ft) to lock onto the target after launch.
After at least two unconfirmed instances of U-boats (U-972 and U-377) sinking after being allegedly hit by their own torpedoes, 
the BdU ordered the submarines to dive to 60 metres (200 ft) and go completely silent after launching acoustic torpedoes to minimize the risk.
The first 80 T5s were delivered on 1 August 1943, and the weapon was first used in a large-scale maneuver against the North Atlantic 
convoys ONS 18/ON 202 in late September 1943. Despite some initial success, in particular sinking destroyers and corvettes, 
the Zaunkönigs effectiveness was quickly nullified by the introduction of a decoy known as Foxer noise maker.
In spite of highly effective Allied countermeasures, a total of over 700 T5s were fired in combat, sinking 77 ships.


G7es (T5) Zaunkönig torpedo characteristics:
Designed: 1933

Length: 7.186 m
Diameter: 533 millimetres (21.0 in)

Effective firing range: 5,750 meters
Search duration: 7,6 minutes
Speed: 24.5 knots

Warhead weight: 274kg




G7es (T11) Zaunkönig II
    Realizing what was happening, the Germans introduced the second generation of acoustic torpedoes which were more accurately tuned to 
a ship’s propeller noise. The G7es Zaunkonig II also had an improved range and sensitivity.
The Zaunkonig II could also be launched from up to depths of 50 meters (164 feet), compared to 15 meters (49 feet) for Zaunkonig I.
    G7es (T11) Zaunkönig II has basically the same characteristics as G7es (T5) Zaunkönig.




Acoustic torpedoes in WoWs

Historically, acoustic torpedoes were only meant as a weapon against surface ships (with the exception of the Mark 24 mine) and 
I would like to keep it that way.
Homing torpedoes should always have lower speed, when compared to torpedoes of DDs.


1) Highly reduce torpedo turning capabilities
This way torpedoes would be only slightly enhanced in comparison to normal torpedoes. The torpedoes would be able to adjust their course but 
with such minimum affect, that it will be only slightly harder for the targeted ship to avade the homing torpedo.


2) Torpedoes homing capabilities would be active after certain distance
G7e/T4 Falke torpedo and G7es (T11) Zaunkönig II had their acoustic searching activated after 400 meters.
In naval combat 400 meters is a short distance. So why don't take this distance, where torpedo is not adjusting its direction, and make it longer.
It could be activated after torpedo travelled for example 10-50% of its maximum range (only testing will say if it is too much/ little or alright...).

This way captains will have to make a choice: 
a) fire at longer distances- torpedo will be adjusting its direction towards target longer but it will take much longer to get to target and thus having
much higher chances that the target will change course (he is evading enemy shells, torpedoes, wants to cap, etc. ...) and torpedo
will miss the target, because of its limited turning capabilities
b) fire at medium distances- torpedo will be adjusting its direction towards target only for a while, shorter time of travelling
c) fire at short distances- homing torpedo will act just like any other in game- it will go in a straight line


3) Torpedoes homing radius
Torpedoes will become homing only after they are in certain distance from target.
What I mean by this is a folowing example:
Submarine fires torpedo. Torpedo goes in a straight line. When the torpedo detects enemy ship in 1 km radius (for example), then it will
starts to hunt down the enemy ship.
This way, you can't alter the target for torpedo, creating sometimes situations, where you aimed for BB, but your torpedo starts chasing enemy DD, 
which is closer to the trajectory of the torpedo and having worse chances to hit. Once the torpedo starts chasing, the target cannot be changed.


4) Firing at lower speeds 
Just like with G7es (T5) Zaunkönig, your submarine doest want to be targeted by it own homing torpedoes.
This gives captains 2 choices:
a) fire torpedo at a straight line, but maintaining higher speed
b) significantly slow down and fire homing torpedoes (being slower=less noise)
Slowing down, while being chased down by a DD can decide your fate.


5) Give other ships and planes noise makers
This could be consumable with 3-4 charges given to ships to defend themselves from homing torpedoes.
Planes would have this to assist their team at front lines of the battle.


6) Targeting friendly ship
Acoustic torpedoes lacked ability to tell friend from foe. If you mark friendly ship by mistake, torpedo will target the friendly vessel.
This is a terrible idea and I hope we won't see it .



Historical part
Acoustic torpedoes were slow (although German torpedoes are faster), couldn't change depth (exept for Mark 24 mine) 
and lacked ability to tell friend from foe. They were meant as a weapon against surface ships (exept for Mark 24 mine).


Possible implementation in game:
By highly reducing torpedo turning capabilities, delaying their homing abilities, reducing submarines speed while firing or giving all other
ships defensive consumables. They also should be against surface ships (not submarines).
Their speed would be higher than in real life (I assume) but lower then other torpedoes.


Submarines have still a long way, before they get to the random battles and maybe we even won't see any homing torpedoes at all.
Who knows, all is a subject that could be changed.

One way or another, Wargaming should be careful about this...


I will be glad if you leave your comment below. I hope you enjoyed this article and have a nice day.
I apologize for any grammar mistakes, english is not my native language.







Book- Německé válečné ponorky 1939-1945- Svojtka a Co.


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9,794 battles

So you want to discuss acoustic torpedoes when Wargaming has already made up their minds and announced that submarine torpedoes will have a kind of homing system via active sonar pings that will expose the position of the submarine?


And what's the point? WG can't implement realistic acoustic torpedoes without the game becoming World of German Submarines. Thus they already figured a fantasy way to deal with it.


- fire torpedo, it goes straight and unguided. It might hit or don't as any regular torpedo.

- blow one sonar ping, torpedo acquires a homing on the target and will try to track it within its maneuverability, but the ping reveals the position of submarine

- second ping will make the torpedo dive to hit under the keel for extra damage and/or home on a submerged enemy submarine, but again will reveal the submarine position


Also pings only are possible at persicope depth with reduced velocity and subject to spalsh damage from close hits (plus depth charges)



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Am 23.8.2019 um 15:55, Bartleby74 sagte:

Thus they already figured a fantasy way to deal with it.

They already figured fantasy ways to deal with quite a lot of things, so at least they remain consistent within World of Balans.

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Beta Tester
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in the real life acoustic torpedoes weren't as good as one would think against warships.


The torps homing on cavitation, but the slow speed  most allied  sailors knew that if you travelled at less than 7 or over 25 knots you were relatively immune to gnats.  They also blew up early many times due exploding in the wake of a cativating ship, and could be easily deceived by foxers and cats.


Added to the fact that less inexperienced crews fired them indiscriminately from distance they were a bit crap.  more for green crews to kill civilian targets.


At that time in the war, escort CVs, hedgehogs and squids had more of an influence.

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