FaT Guidance system
A new direction control system was ready at the end of 1942, the FaT (Federapparat Torpedo, but some sources also refer to this as the Flächenabsuchender Torpedo). This system allowed the torpedo runs to be set before the torpedo launch, in fact, programming a pattern of direction. For instance, you could set a torpedo, so that after an primary run of 1200 meters, it changed direction for 400 meters, and then returned back to its original course, creating in this manner, a search pattern. If no impact occurred after the primary run, the torpedo turned back, and then again, until any vessel was hit, or until the maximum run lenght was achieved. The ideal was for this torpedo to be launched behind a convoy. The FAT device was installed first in the G7a torpedos, and since they left a visible bubble trail, its use was limited to night attacks. As light modification of the FAT device, the FATII, was installed first in the G7e torpedos, that were then renamed, TIII G7e FaTII, from March 1943. These should be launched from the stern, to attack an escort chasing an uboat. After the first run, the torpedo would run circles, always turned to the left. The FaTII entered service in May 1943, but it didn't had good results, thanks to its short autonomy (5000m), and thanks to this, a new version was built, the TIIIa FaTII (G7e), that, with a larger battery capacity, allowed a range of 7315 meters.
LuT Guidance system
In March 1944, a new torpedo guidance device appear, the LuT (Lagenunabhängiger Torpedo), which was developed from the FaT design, but that incorporated some improvements in the search pattern. Now it was possible to set a new course, after a primary run, this new course , allowed the torpedo to follow the course of the convoy, to then start a zigzag search pattern. This zigzag distance, would be set to be anything from 0 to 1600 meters, while on the original FaT only 2 options were available. The velocity of the torpedo was also improved, and its speed could be set
between 5 to 21 k nots. The LuT was installed in the G7a (TI LuTI G7a), and in the electric version of the same (TI LuTI G7e), with increased autonomy. A new version, the LuTII, allowed changes of course of 180°. The LuT wasn't used in combat until 1944, and only some 70 of them were used operationally.
TI G7a "Ato"
Geräte -Nr.: 12
Diameter: 533,4mm
Weight: 1538Kg
Length: 7163mm
Charge: Ka, or Kc280 warheads , 280Kg (Hexanite).
Pistol: Pi1 or TZ3 with Pi3 (contact or contact coupled with passive magnetic).
Arming: 250m (pre 1943)
150m (post 1943)
Buoyancy(%): 21
Range /Speed: 6000m /44Kn (not used in early war)
7500m /40Kn (early war)
12500m /30Kn (early war)
6000m /44Kn (later in the war)
8000m /40Kn (later in the war)
14000m /30Kn (later in the war)
Power: Decahydronaphthalene (Decalin) Wet-Heater, 4 cylinders
108hp at 9 40U/min (early war)
241hp at 1270U/min (early war)
300hp at 1500U/min (early war)
255hp at 1280U/min (later in the war)
350hp at 1470U/min (later in the war)
Notes:
44k knots settings were found to overload the engine and weren't used during the early years of the war.
The early models used in 1939 had ranges about 20% less than the standard specified of 6000m /44Kn, 8000m /40Kn, 14000m /30Kn, being in fact of 7500m /40Kn and 12500/30Kn.
Power also changed, from
108hp/940U/min,
241hp/1270U/min,
300hp/1500U/min,
to
255hp/1280U/min, and 350hp/1470U/min.
The warhead was a Ka280 or Kc280, with 280Kg of Hexanite. Explosive charge was usually
60% TNT and 40% hexanitrodiphelylamine, in various mixes:
SW18: 50% TNT, 24% HND, 15% aluminium.
SW36: 67% TNT, 8% HND, 25% aluminium.
SW39: 45% TNT, 5% HND, 30% amonium nitrate , 20% aluminium.
SW39a: 50% TNT, 10% HND, 5% amonium nitrate, 35% aluminium.
Note, wake was much more visible at 40Kn, since air consuption changed from 13.6 atü
at 30Kn, to 24.3 atü at 40Kn.
TI G7a "Ato" FaTI
Geräte-Nr.: 12
Diameter: 533,4mm
Weight: 1538Kg
Length: 7163mm
Charge: Ka, or Kc280 warheads, 280Kg (Hexanite).
Pistol: Pi1 or TZ3 with Pi3 (contact or contact coupled with passive magnetic).
Arming: 250m (pre 1943)
150m (post 1943)
Buoyancy(%): 21
Range/Speed: 6000m /44Kn (not used in early war)
7500m /40Kn (early war)
12500m /30Kn (early war)
6000m /44Kn (later in the war)
8000m /40Kn (later in the war)
14000m /30Kn (later in the war)
Power: Decahydronaphthalene (Decalin) Wet-H eater, 4 cylinders
108hp at 940U/min (early war)
241hp at 1270U/min (early war)
300hp at 1500U/m in (early war)
255hp at 1280U/min (later in the war)
350hp at 1470U/min (later in the war)
Notes:
44knots settings were found to overload the engine and weren't used during the early
years of the war. The early models used in 1939 had ranges about 20% less than the
standard specified of 6000m /44Kn, 8000m /40Kn, 14000m /30Kn, being in fact of
7500m /40Kn and 12500/30Kn. Power also changed, from
108hp/9 40U/min,
241hp/1270U/min,
300hp/1500U/min,
to
255hp/1280U/min, and 350hp/1470U/min.
The warhead was a Ka280 or Kc280, with 280Kg of Hexanite. Explosive charge was usually
60% TNT and 40% hexanitrodiphelylamine, in various mixes:
SW18: 50% TNT, 24% HND, 15% aluminium.
SW36: 67% TNT, 8% HND, 25% aluminium.
SW39: 45% TNT, 5% HND, 30% amonium nitrate, 20% aluminium.
SW39a: 50% TNT, 10% HND, 5% amonium nitrate, 35% aluminium.
Note, wake was much more visible at 40Kn, since air consuption changed from 13.6 atü
at 30Kn, to 24.3 atü at 40Kn.
FaT stands for "Flächenabsuchenden Torpedo" or for "Federapparat Torpedo". After a
primary run of between 1600m to 3200m , if nothing was hit, it would turn 90 or 180
degrees to the left or to the right, and make secondary runs of either 800m or 1600m,
until either a target was hit, or batteries were exausted.
On the firing of a FaT torpedo, other uboats had to be warned, otherwise they would risk
being hit by friendly FaT torpedos .
Standard procedure was to dive to 50 meters depth.
Note that the FaTI guidance system was only coupled to the TI G7a torpedo, while the
FaTII guidance system, was only coupled to the TIII G7e torpedo.
TI G7a "Ato" LuTI
Geräte-Nr.: 12
Diameter: 533,4mm
Weight: 1538Kg
Length: 7163mm
Charge: Ka, or Kc280 warheads, 280Kg (Hexanite).
Pistol: Pi1 or TZ3 with Pi3 (contact or contact coupled with passive magnetic).
Arming: 250m (pre 1943)
150m (post 1943)
Buoyancy(%): 21
Range/Speed: 6000m/44Kn (not used in early war)
7500m/40Kn (early war)
12500m/30Kn (early war)
6000m/44Kn (later in the war)
8000m/40Kn (later in the war)
14000m/30Kn (later in the war)
Power: Decahydronaphthalene (Decalin) Wet-Heater, 4 cylinders
108hp at 9 40U/min (early war)
241hp at 1270U/min (early war)
300hp at 1500U/min (early war)
255hp at 1280U/min (later in the war)
350hp at 1470U/min (later in the war)
Notes :
44 knots settings were found to overload the engine and weren't used during the early
years of the war. The early models used in 1939 had ranges about 20% less than the
standard specified of 6000m /44Kn, 8000m /40Kn, 14000m /30Kn, being in fact of
7500m /40Kn and 12500/30Kn. Power also changed, from
108hp/940U/min,
241hp/1270U/min,
300hp/1500U/min,
to
255hp/1280U/min, and 350hp/1470U/min.
The warhead was a Ka280 or Kc280, with 280Kg of Hexanite. Explosive charge was usually
60% TNT and 40% hexanitrodiphelylamine, in various mixes:
SW18: 50% TNT, 24% HND, 15% aluminium.
SW36: 67% TNT, 8% HND, 25% aluminium.
SW39: 45% TNT, 5% HND, 30% amonium nitrate, 20% aluminium.
SW39a: 50% TNT, 10% HND, 5% amonium nitrate, 35% aluminium.
LuTI ("Lagenunabhängiger Torpedo") version of TI G7a torpedo.
TI LuTII G7a
Geräte-Nr.: 29
Diameter: 533,4mm
Weight: 1538Kg
Length: 7163mm
Charge: Ka, or Kc280 warheads, 280Kg (Hexanite).
Pistol: Pi1 or TZ3 with Pi3 (contact or contact coupled with passive magnetic).
Arming: 250m (pre 1943)
150m (pos t 1943)
Buoyancy(%): 21
Range/Speed: 6000m /44Kn (not used in early war)
7500m /40Kn (early war)
12500m /30Kn (early war)
6000m /44Kn (later in the war)
8000m /40Kn (later in the war)
14000m /30Kn (later in the war)
Power: Decahydronaphthalene (Decalin) Wet-Heater, 4 cylinders
108hp at 940U/min (early war)
241hp at 1270U/min (early war)
300hp at 1500U/min (early war)
255hp at 1280U/min (later in the war)
350hp at 1470U/min (later in the war)
Notes:
44knots settings were found to overload the engine and weren't used during the early
years of the war. The early models used in 1939 had ranges about 20% less than the
standard specified of 6000m /44Kn, 8000m /40Kn, 14000m /30Kn, being in fact of
7500m /40Kn and 12500/30Kn. Power also changed, from
108hp/940U/min,
241hp/1270U/min,
300hp/1500U/min,
to
255hp/1280U/min, and 350h p/1470U/min.
The warhead was a Ka280 or Kc280, with 280Kg of Hexanite. Explosive charge was usually
60% TNT and 40% hexanitrodiphelylamine, in various mixes:
SW18: 50% TNT, 24% HND, 15% aluminium.
SW36: 67% TNT, 8% H ND, 25% aluminium.
SW39: 45% TNT, 5% HND, 30% amonium nitrate, 20% aluminium.
SW39a: 50% TNT, 10% HND, 5% amonium nitrate, 35% aluminium.
LuT II ("Lagenunabhängiger Torpedo") version of TI G7a torpedo.
TII G7e "Eto"
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1608Kg
Lenght: 7163mm
Charge: Ka280, 280Kg
Pistol: Pi1 (Pi G7a AZ contact pistol)
Arming: 250m
Buoyancy(%): 21
Range/Speed: 5000m /30kn at 1700U/min, preheated at 30'C
3000m /28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 13T210 batteries
91V/950A 72KW at 1755U/min (preheated at 30'C)
83V/885A 60KW at 1590U/min (not preheated)
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 5000m /30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated range is 3000m /28Kn. Some sources mention a 300Kg charge.
TIII G7e "Eto"
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1608Kg
Length: 7163mm
Charge: Ka280, 280Kg
Pistol: Pi2 (Pi G7H AZ /MZ (contact pistol coupled with passive magnetic pistol)
Arming: 150m
Buoyancy(%): 21
Range/Speed: 5000m /30kn at 1700U/min, preheated at 30'C
3000m /28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 13T210 batteries
91V/950A 72KW at 1755U/min (preheated at 30'C)
83V/885A 60KW at 1590U/min (not preheated)
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 5000m /30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated ranges are 3000m /28Kn. This version used an influence pistol, the Pi2 (Pi G7H AZ /MZ), which had an impact pistol, similar to the Pi1 impact pistol, coupled with an
passive magnetic TZ3 pistol.
The torpedo could be set via a switch, to either use only the impact pistol (AZ), or the
impact + magnetic (MZ).
The warhead used TNT+ HND (Trinitrotoluene + Hexanitrophenylamine)
TIII FaTII G7e
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1620Kg
Length: 7163mm
Charge: Ka280, 280Kg
Pistol: Pi2 (Pi G7H AZ/MZ (contact pistol coupled with passive magnetic)
Arming: 150m
Buoyancy(%): 21
Range/Speed: 5000m /30kn at 1700U/min, preheated at 30'C
3000m /28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 13T210 batteries
91V/950A 72KW at 1755U/min (preheated at 30'C)
83V/885A 60KW at 1590U/min (not preheated)
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 5000m /30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated range is 3000m /28Kn.
This version used a influence pistol, the Pi2 (Pi G7H AZ /MZ).
The warhead used TNT+ HND (Trinitrotoluene + Hexanitrophenylamine).
This was the FaT version of the TIII G7e.
TIIIa FaTII G7e
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1760Kg
Length: 7163mm
Charge: Ka280, 280Kg
Pistol: Pi2 (Pi G7H AZ/MZ (contact pis tol coupled with passive magnetic pistol)
Arming: 150m
Buoyancy(%) : 32
Range /Speed: 7500m /30kn at 1700U/min, preheated at 30'C
4500m /28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 17T210 batteries, 125A/hour
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 7500m /30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated range is 4500m /28Kn. This version used an influence pistol, the Pi2 (Pi G7H AZ /MZ),
which had an impact pistol, similar to the Pi1 impact pistol, coupled with an
passive magnetic TZ3 pistol.
The torpedo could be set via a switch, to either use only the impact pistol (AZ), or the
impact+ magnetic (MZ).
The warhead used TNT+HND (Trinitrotoluene + Hexanitrophenylamine)
This was the FaTII version of the TIII G7e (note that TIII G7e 's only had FaTII guidance
devices, FaTI were only used on TI G7a torpedos).
This torpedo used two 17T210 batteries , with a larger capacity of 125 Amperes /hour,
compared to the 13T210 batteries, which had a capacity of 93 Amperes/hour.
TIIIa LuTI G7e
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1760Kg
Length: 7163mm
Charge: Kb280, 280Kg
Pistol: Pi2 - Pi G7H AZ /MZ (contact pistol coupled with passive magnetic pistol)
Arming: 150m
Buoyancy(%): 32
Range/Speed: 7500m /30kn at 1700U/min, preheated at 30'C,
4500m/28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 17T210 batteries, 125A/hour
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 7500m /30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated range is 4500m/28Kn. This version used an influence pistol, the Pi2 (Pi
G7H AZ /MZ), which had an impact pistol, similar to the Pi1 impact pistol, coupled with an
passive magnetic TZ3 pistol.
The torpedo could be set via a switch, to either use only the impact pistol (AZ), or the
impact+magnetic (MZ).
The warhead used TNT+HND (Trinitrotoluene + Hexanitrophenylamine)
This was the LuTI version of the TIII G7e torpedo.
This torpedo used two 17T210 batteries , with a larger capacity of 125 Amperes/hour,
compared to the 13T210 batteries , which had a capacity of 93 Amperes/hour.
TIIIa LuTII G7e
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 1760Kg
Length: 7163mm
Charge: Kb280, 280Kg
Pistol: Pi2 - Pi G7H AZ/MZ (contact pistol coupled with passive magnetic pistol)
Arming: 150m
Buoyancy(%): 32
Range/Speed: 7500m /30kn at 1700U/min, preheated at 30'C
4500m /28Kn not preheated.
Power: Siemens GL231/75 E-Motor, 100hp, 2x 17T210 batteries, 125A/hour
Notes:
This unit used a 100hp Siemens GL231/75 electric motor, that drove two contra-rotating
propellers. The above range and speed of 7500m/30Kn could be reached only if the
batteries were preheated to 30'C. These torpedoes had to be serviced every 3 to 5 days
in order to maintain their reliability.
Not preheated range is 4500m /28Kn. This version used an influence pistol, the Pi2 (Pi
G7H AZ /MZ), which had an impact pistol, similar to the Pi1 impact pistol, couple with an
passive magnetic TZ3 pistol.
The torpedo could be set via a switch , to either use only the impact pistol (AZ) , or the
impact+magnetic (MZ).
The warhead used TNT+HND (Trinitrotoluene + Hexanitrophenylamine).
This was the LuTII version of the TIII G7e torpedo.
This torpedo used two 17T210 batteries, with a larger capacity of 125 Amperes/hour,
compared to the 13T210 batteries, which had a capacity of 93 Amperes/hour.
TIIId G7e "Dackel"
Geräte-Nr: 20
Diameter: 534,6mm
Weight: 2220Kg
Length: 11000mm
Charge: Kb280, 280Kg
Pistol: PiZ
Arming: 150m
Buoyancy(%): 1,5
Range/Speed: 57000m /9Kn at 505U/min
Power: Siemens GL231/75 E-Motor, 100hp, 4x 17T210 batteries
5KW at 505U/min
Notes:
This was a very long range , slow speed, version of the TIII G7e torpedo, intended for use
in harbours , or restricted bays. It could be programmed with a specific circling, or legs at
the end of a straight run.
It had four 17T210 bateries. Due to the extremely long runs, torpedo preheating was not so important.
TIV G7e s "Falke"
Geräte-Nr: 37
Diameter: 534,6mm
Weight: 1937Kg
Lenght: 7163mm
Charge: Kd280, 274Kg
Pistol: Pi4a
Arming: 150m
Buoyancy(%): ?
Range/Speed: 7500m /20kn at 1125U/min, preheated at 30'C
4500m/16Kn not preheated.
Power: Siemens GL?/? E-Motor, 32h p, 1x 13T210 batteries
24KW at 1125U/min (preheated at 30'C)
20KW at 985U/min (not preheated)
Notes:
The first passive homing torpedo. Homing was made by a simple noise measurement.
Intended to use against merchant ships, so the low speed was acceptable.
The T4 Model was the adjunct of the earlier T3 model in nearly every way. However, this
was no ordinary straight running torpedo, but the world's first acoustic homing torpedo.
In early 1933, Germany started development and testing of acoustic homing mechanisms
for torpedoes. From the outset of submarine warfare, it had been a dream to be able to
aim and fire torpedoes without the aid of a periscope, because the periscope gives away
the location of a submarine, and because a hull-penetrating periscope greatly weakens a
submarine's pressure hull and lim its the depths to which it can dive. U-boats also had to
come to very shallow depths to use their periscopes, generally about 15 m , leaving them
greatly exposed to bombing, depth charging, and even gunfire .
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 theirs crews. Rather than
aiming with a periscope, the torpedo could be roughly aimed at a sound contact as
detected by a U-boat's hydrophones, and the homing mechanism could be trusted to find
the target without the need for precise aiming.
Falke worked much like a normal straight running torpedo for the first 400 m of its run,
whence its acoustic sensors became active and searched for a target. The sensitive
sound sensing equipment in Falke required the torpedo to be as quiet as possible, hence it
ran at only 20Kn; in addition, the firing U-boat was forced to stop its motors. Falke was
intended to home on merchant targets, however, so Falke 's slow speed was not a great
hindrance .
TV G7e s "Zaukönig I"
Geräte-Nr: 45
Diameter: 534,6mm
Weight: 1495Kg
Lenght: 7163mm
Charge: Ke 1, 274Kg
Pistol: TZ 5, Pi4b, Pi4c
Arming: 150m with Pi4c and TZ5, 400m with Pi4b.
Untertrieb(% ): 11
Range/Speed: 5750m/24.5kn at 1125U/min, preheated at 30'C
3750m/20Kn not preheated.
Power: Siemens GL?/? E-Motor, 55hp, 1x13T210 batteries
40KW at 1350U/min (preheated at 30'C)
32KW at 1175U/min (not preheated)
Notes:
This torpedo was meant to be used against convoy escorts. Designed to home in on the
caviation noise of around 24.5KHz which was equivalent to propellers on an escort
travelling at 10 to 18Kn. First sucess full combat use was made in September 1943.
There were two main variants:
Flat-nosed version which contained two sets of magnetos triction hydrophones.
Round-nosed version which contained two magnetos triction hydrophones inside a
funnel shaped baffle.
The TV also introduced the TZ5 (active) magnetic pistol, which was basically a metal
detector with two coils, and solved much of the problems of early magnetic pistols. An
improved TZ6 pistol could be fitted to any G series torpedo (53.3cm diameter), but was
only approved for use as the war ended.
Most torpedos used whis ker-type impact pistols, but these could not be used on hom ing torpedos. Therefore these types of torpedos used an inertial pistol in the rear of the
warhead, and the TV could use a coupled magnetic and inertial impact pistol.
The acoustic homing device would only lock to the loudest noise after a run of 400m from its launch with a Pi4b pistol, and 150m from its launch with a Pi4c pistol, to avoid locking on the launching uboat. In such cases, standard orders were to dive imediately to a depth of 60 meters after launch, if the launch was made from a bow tube. If the launch was made from a stern tube, complete uboat silence was required.
TVb G7e s "Zaukönig I"
Geräte-Nr: 45
Diameter: 534,6mm
Weight: 1495Kg
Lenght: 7163mm
Charge: Ke 1,274Kg
Pistol: TZ5, Pi4b, Pi4c
Arming: 150m with Pi4c and TZ5, 400m with Pi4b.
Untertrieb(%): 11
Range/Speed: 8000m/21.5kn at 1210U/min, preheated at 30'C
5750m/20Kn not preheated.
Power: Siemens GL?/? E-Motor, 40hp, 1x 17T210 batteries
30KW at 1210U/min (preheated at 30'C)
26KW at 1050U/min (not preheated)
Notes:
This torpedo was meant to be used against convoy escorts. Designed to home in on the
caviation noise of around 24.5KHz which was equivalent to propellers on an escort
travelling at 10 to 18Kn. First sucess full combat use was made in September 1943.
Th e TV also introduced the TZ5 (active) magnetic pistol, which was basically a metal
detector with two coils, and solved much of the problems of early magnetic pistols. An
improved TZ6 pistol could be fitted to any G series torpedo (53.3cm diameter), but was
only approved for use as the ware nded.
Most torpedos used whis ker-type impact pistols, but these could not be used on homing torpedos. Therefore these types of torpedos used an inertial pistol in the rear of the warhead, and the TV could use a coupled magnetic and inertial impact pistol.
The acoustic homing device would only lock to the loudest noise after a run of 400m from its launch with a Pi4b pistol, and 150m from its launch, with a Pi4c pistol, to avoid locking on the launching uboat. In such cases, standard orders were to dive imediately to a depth of 60 meters, after launch, if the launch was made from a bow tube. If the launch was made from a stern tube, complete uboat silence was required.
This variant had an increased range, thanks to a larger capacity battery, the 17T210,
and 2 auxilliary boosters ("Zusatztröge"). The TVa was th e S-boot version of this torpedo.
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