PowerPoint Presentation · - Influence from sound-velocity gradients are generally larger, meaning that significant refraction occurs. - A submarine can hide near or on the seabed,

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ORUWA / Thomas Petersson | Issue 1

UDT 2020

ORUWA / Thomas Petersson

2020-02-25

ASW using LWTs from Submarines



ASW Using LWTs from Submarines

• Background

• ASW – The Challenge

• ASW from Surface Units

• ASW from Submarines

• LWTs on Submarines

• Current Swedish LWTs

• Summary

2



Background – HWTs in Sweden

3

3

Operational



Background – LWTs in Sweden

4

4

Operational

and New



Background – LWTs in Sweden

5

Surface Ship

Craft of Opportunity

Aircraft

Submarine



ASW – The Challenge

• In blue waters:

- Few problems exist with hydro acoustic disturbancescaused by reverberation and other sources of noise.

- When a target is detected, the possibilities toescape are limited.

- A fire-and-forget torpedo can be used effectively.The launch trajectory and the time required to enter acontrolled and stable run are less critical.

- A torpedo must be dimensioned to sustain the waterpressure when combating deep sea targets.

• In shallow waters:

- Reverberation from the surface and from the seabed,and other sources of noise, are frequent.

- Influence from sound-velocity gradients are generallylarger, meaning that significant refraction occurs.

- A submarine can hide near or on the seabed,in areas where seabed reverberation is high.

- The systems must be designed for shallow watersand a complex hydro acoustic environment.

6

X

Y

Z

X

Y

In deep waters the distance to the target

can be in the same order of magnitude

as the water depth.

This can be generalised into a three

dimensional scenario (X-Y-Z volume).

In shallow waters the combat- and detection

ranges can be much greater than

the depth. Here the majority of actions

take place over a horizontal area.

This can be generalized into a two

dimensional scenario (X-Y plane).



ASW – The Challenge

7

Sound Velocity

Shadow Zone

Distance from the transmitter

Sound VelocityDistance from the transmitter

Baltic Sea - Winter Conditions

Distance from the transmitter

Sound Velocity

Shadow Zone

Shadow Zone

Sound VelocityDistance from the transmitter

Baltic Sea - Summer Conditions



ASW from Surface Units

• In Anti-Submarine Warfare (ASW) from a surface unit

there is an asymmetry between hunter and target:

- The detection range for a Hull Mounted Sonar (HMS)

or a Dipping Sonar (DS) can be extremely reduced.

- The submarine takes advantage of

hydro-acoustic shadow zones.

- The surface units may be affected by adverse weather

conditions and hostile activities.

8



ASW from Submarines

• In Anti-Submarine Warfare (ASW) from a submarine the

asymmetry between hunter and target is reduced:

- The detection ranges for the submarine sensors

(FAS and CAS) are comparable.

- Both submarines can utilize hydro-acoustic shadow zones

to their advantage.

- Both submarines operate in the same environment and are

not affected by the sea state and weather conditions.

9



LWTs on Submarines – Dedicated Tubes

10

VGD Class Arrangement

6 x HWT Tubes

3 x LWT Tubes (x 2 Torpedoes)

Total: 6 + 6 Torpedoes (RTF)

GTD Class Arrangement

4 x HWT Tubes





LWTs on Submarines – 53 cm Tubes

11

For integration of LWTs

on submarines equipped

with HWT tubes.

A tube insert that can be handled as a unit load is used to adapt

the existing 53 cm torpedo tubes to the LWTs.



LWTs on Submarines – Dedicated Tubes

12

Torpedoes are taken

onboard using the same

systems and methods

as used for HWTs.



LWTs on Submarines – Logical Integration

13

GTD Class Arrangement

4 x HWT Tubes





Current Swedish LWTs

14

Torpedo 45 Torpedo 47ASW/(ASuW) ASW/(ASuW)



Current Swedish LWTs - Tp47 Overview

15

FLS

Proximity

Fuse

Stator / Rotor / Duct

Warhead

Computer & Electronics

Battery(Lithium Iron Phosphate)

Wire / Fibre Magazine

ConnectorMotor

Servos / Rudders

FLS Electronics

SAI

Torpedo 47 Key Features

• Homing System Resolution

• Communication by Wire

• Wide Speed Range

• Neutral Buoyancy

• Endurance

• Silent Run



LWTs on Submarines – Benefits

• From an operational perspective

- Optimized solution using a submarine for ASW

- Provides a secondary additional ASuW capability

- Can be used as a self defence weapon

- Evolutionary use as an Anti-Torpedo Torpedo (ATT)

• From a logistics perspective

- Weapon system with smaller on-board footprint

- Increases the number of ready to fire torpedoes

• From a design perspective:

- Robust and can withstand higher shock-loads

16



Summary

• LWTs on Swedish Submarines- Utilizes dedicated smaller torpedo tubes

- Have been operational for decades

• A Tube Insert can be used for integration- Can be handled as a unit load

- Compatible with existing HWT handling systems

- Flexible use of the fixed HWT tubes

• Using LWTs from submarines- Smaller on-board footprint

- Increased number of RTF torpedoes

- Robust system

- Additional self defense capability

17



Thank YouThomas Petersson / ORUWA

Documents

PowerPoint Presentation · - Influence from sound-velocity gradients are generally larger, meaning that significant refraction occurs. - A submarine can hide near or on the seabed,