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OP 1586
TORPEDO FIRE CONTROL EQUIPMENT
(DESTROYER TYPE)
TORPEDO DIRECTOR MARK 27
TELESCOPE MARK 50
FIRING KEY MARK 19
TORPEDO COURSE INDICATOR MARK 1
A BUREAU OF ORDNANCE PUBLICATION 27 FEBRUARY 1947

RESTRICTED OP 1586

TORPEDO CONTROL EQIUPMENT
(DESTROYER TYPE)

----

TORPEDO DIRECTOR MARK 27
TELESCOPE MARK 50
FIRING KEY MARK 19
TORPEDO COURSE INDICATOR MARK 1

Department of Navy, Bureau of Ordnance Seal

27 FEBRUARY 1947


This publication is RESTRICTED and shall be safeguarded in accordance with the security provisions of U. S. Navy Regulations 1920, Article 76.


 
NAVY DEPARTMENT
BUREAU OF ORDNANCE
WASHINGTON 25, D. C.

27 February 1947

RESTRICTED

ORDNANCE PAMPHLET 1586

TORPEDO DIRECTOR MARK 27 MODS 1 TO 9
WITH TELESCOPE MARK 50 MODS 0 AND 1,
FIRING KEY MARK 19 MODS 0 AND 1,
AND THE TORPEDO INDICATOR MARK 1 MODS 0 TO 4

1. This Ordnance Pamphlet contains information on the description, operation, installation, maintenance, and overhaul of destroyer type fire control equipment. The equipment includes the Torpedo Director Mark 27 Mods 1 to 9 with Telescope Mark 50 Mods 0 and 1 and Firing Key Mark 19 Mods 0 and 1 installed and the Torpedo Indicator Mark 1 Mods 0 to 4.

2. The description of the torpedo director includes the alterations which were authorized by the following NAVORD ORDALTS:

ORDALT 1255-Instructions for installing centering device for sight angle motor follow-up
ORDALT 1787-Installation of red illumination for dials
ORDALT 2107-Installation of relative target bearing receiver
3. This publication supersedes Ordnance Pamphlet 585 (Second Revision), which should be destroyed

4. Ordnance Pamphlet 1586 is RESTRICTED and shall be safeguarded ordnance with the security provisions of U. S. Navy Regulations, 1920, Article 76.

Signature of G.F. Hussey, Jr.
G. F. HUSSEY, JR.
Vice Admiral, U. S. Navy
Chief of Bureau of Ordnance

CONTENTS

CHAPTER PAGE
1 Terminology 1
Computing Latitude Correction 4
 
2 Introduction 5
How the Director Solves the Torpedo Fire Triangle 7
Inputs and Outputs 8
Differences Between Mods of the Director 12
Differences Between Mods of the Indicator 13
 
3 Functional Description 15
How the Director Works 15
How the Indicator Works 17
How the Telescope Works 19
 
4 Operation 21
Personnel Required 21
How to Read the Dials 23
Source of Information for Inputs 29
Operation Routine 29
 
5 Description 31
Director 31
  Computer Assembly 35
  Own Ship Course Assembly 45
  Transmitter Assembly or Unit 52
  Back Post Assembly 54
  Bearing Receivers 54
  Rheostat Assembly 61
  Telescope Pivot Assembly 61
  Hand Cranks 61
  Dials 64
  Stand 66
System Electrical Components 68
  Circuits 70
  Signals and Firing 72
  Wiring 72
Indicator 73
Telescope 81
CHAPTER PAGE
Firing Key 84
  Portable Contact Maker 85
 
6 Installation 86
Director 86
  Test Problems (figures 89 and 90) 96-97
Indicator 89
Telescope 92
  Firing Key 92
 
7 Installation Checks and Adjustments 93
Director 93
  Test Problems (figures 102 and 103) 112
Indicator 97
 
8 Maintenance 98
Director 98
  Periodic Checks and Lubrication 98
  Trouble Shooting Chart 101-102
Probable Operation Difficulties of System 103
Indicator 100
  Periodic Checks and Lubrication 100
  Trouble Shooting Chart 104
Telescope 100
 
9 Replacement of Electrical Units 105
 
10 Disassembly, Overhaul, Assembly, Adjustment 111
Disassembly and Overhaul 111
  Director 111
  Indicator 124
  Telescope 124
Assembly and Adjustment 126
  Director 126
  Indicator 141
  Telescope 141
 
APPENDIX-
General Information 142
Principal Drawings 145
Element Numbers 146

Figure 146-Functional diagram showing course of inputs and outputs through the Torpedo Director Mk 27 Mods 1,3,4,5,7,8 and 9. 147
Operation Routine 148
Figure 147-Diagram of suggested operation routine. 149
Figure 148-Schematic mechanical diagram of computer shafting and gearing. 150
Figure 149-Mechanical diagram of Torpedo Director Mk 27 Mods 1, 3, 4, 5, 7, 8 and 9. 151
Figure 150-Mechanical diagram of Torpedo Director Mk 27 Mod 2 153
Figure 151-Torpedo control system-circuit GA, elementary wiring diagram. 155
Figure 152-Torpedo firing and ready light system-circuit 6PA and 6R, elementary wiring diagram. 157
Figure 153-Torpedo Director Mk 27 Mods 1,2,3,4 and 5-internal wiring diagram. 159
Figure 154-Torpedo Director Mk 27 Mods 7,8, and 9-internal wiring diagram. 161
Figure 155-Torpedo Director Mk 27 Mod 2-interal wiring diagram. 163
 
iii

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Photo of Torpedo Director Mk 27 installed on the bridge .
Figure 1-Torpedo Director Mk 27 Mods 1 to 9 is a torpedo fire control instrument. This view shows the director installed on the bridge of a modern destroyer.
 
iv

Chapter I

TERMINOLOGY
 

This section defines the basic torpedo fire control terms used in this manual. A thorough understanding of these terms at the start will help clarify the principles and operation of the torpedo director.
Firing Point: This is the point where the torpedo begins its run; broadly, the position of own ship when the torpedo is fired.
Line of Sight: The straight line from the axis of rotation of the torpedo director to the point of aim on the target.
Point of Aim: The desired point on the target to be hit with the torpedo.
Torpedo Track: The path along which the torpedo proceeds through the water.

Usually, when a torpedo is fired, it travels in a straight line for a certain distance called the reach. At the end of this period of straight line travel, it may be caused to start on a circular course. The arc of the circular path is determined by setting the gyro in the torpedo. At the end of the circular path, the torpedo proceeds to the target in a straight line. This final straight line of the torpedo is called final track of the torpedo.

The various torpedo fire control symbols and terms, defined below, are illustrated in figure 2.

Symbol Definition
B True Target Bearing: The angle between the north-south line and the line of sight to thetarget, measured clockwise from the north (measured from 0 degrees to 360 degrees).
Bgy Gyro Angle: The angle between the axis of the torpedo tube and the final track of the actual torpedo, measured clockwise from the torpedo tube (measured from 0 degrees to 360 degrees). Gyro Angle Order is the value of gyro angle which is ordered to be set into the torpedo. In the torpedo fire control system described in this manual, gyro angle order is transmitted electrically at two-speed from the torpedo director to the torpedo course indicators at the torpedo tube mounts.
 
Bt Target Angle: The angle between the fore and after axis of the target and the line of sight to the target, measured clockwise from the target's bow (measured from 0 degrees to 360 degrees).
Bs Relative Target Bearing: The angle between the fore and after axis of own ship and the line of sight to the target, measured clockwise from the own ship's bow (measured from 0 degrees to 360 degrees).
Bto Torpedo Course: In this manual reference is made to torpedo course. This term should be called Relative Torpedo Course because it is torpedo course angle measured relative to own ship.

TorpedoCourse (relative) is the angle between fore and after axis of own ship and the final track of the actual torpedo, measured clockwise from the ship's bow (measured froth 0 degrees to 360 degrees).

Torpedo Course Order is the value of torpedo course computed by the director.

Btr Track Angle: The angle between the final track of the torpedo and the fore and after axis of the target measured clockwise from the bow of the target.
Btu Basic Tube Train: The computed angle between the fore and after axis of own ship and the axis of the torpedo tube mount measured clockwise from the ship's bow (measured from 0 degrees to 360 degrees). Basic tube train does not include tube offset.
B'tuActual Tube Train: The angle between the fore and after axis of own ship and the axis of the torpedo tube mount, corrected for tube offset, measured clockwise from the ship's bow (measured from 0 degrees to 360 degrees). In this manual, actual tube train does include tube offset and is equal to the algebraic sum of torpedo course (corrected for tube offset) and gyro angle. Figure 2 illustrates the case where actual tube train is equal to torpedo course minus gyro angle.
 
1

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) - OP 1586
 
Graphic showing all of the terms described in the text
Figure 2-Graphic explanation of terminology.
 
2

TERMINOLOGY
 
  Thus, actual tube train is the angle that the torpedo tubes make with the fore and After axis of own ship when torpedo course and gyro angle dials of the torpedo course indicator are matched. For a complete description of how actual tube train is produced, see page 11.
Co Own Ship Course: The angle between the north-south line and the fore and after axis of own ship, measured clockwise from the north to the bow of own ship (measured from 0 degrees to 360 degrees).
Ct Target Course: The angle between the north-south line and the fore and after axis of the target, measured clockwise from north to the bow of the target (measured from 0 degrees to 360 degrees).
Ds Basic Sight Angle: The computed angle from the line of sight to the final track of the torpedo measured clockwise.
Dsk Corrected Sight Angle: This is basic sight angle with latitude correction and intercept offset correction applied.
H Target Run: Distance run by target during the time of torpedo run.
Kla Latitude Correction: The correction required to compensate for the error due to proving (balancing) a torpedo gyro in one latitude and firing it in another. In other words, this correction is a change in sight angle to compensate for the inherent tendency of the torpedo to creep to the right in northern latitudes and to the left in southern latitudes, due to the earth's rotation. This quantity depends upon latitude and duration of the torpedo run.
Osi Intercept Offset: This is an arbitrary change in sight angle, right or left, to produce an offset angle, thus changing the point of intercept.
Otu Tube Offset: The angle between the tube mount axis and the basic tube train measured right or left from the basic tube train.

In other words, tube offset is the angle by which torpedo course orders, transmitted from the director to the two torpedo tube mounts, are diverged

 
  symmetrically about the basic (computed) torpedo course to obtain a spread between the mounts. In the torpedo director, tube offset is the angle between basic torpedo course and actual torpedo course.
Q Spread Angle: The angular difference between the final track of two adjacent torpedoes fired from the same tube mount exclusive of any change in basic gyro angle of the torpedoes.
So Own Ship Speed: Speed of own ship in knots.
St Target Speed: Speed of target in knots.
Sto Torpedo Speed: The average speed, in knots, of the actual torpedo from the muzzle of the tube to the point of intercept.
Xt Target Deflection: This is the component of target speed, perpendicular to the line of sight. In the torpedo director, this term is computed according to the equation,

Xt = St Sin Bt. Target deflection equals target speed times the sine of target angle.

Xto Torpedo Deflection: This is the component of torpedo speed, perpendicular to the line of sight. In the torpedo director, this term is computed according to the equation,

Xto = Sto Sin Ds. Torpedo deflection equals torpedo speed times the sine of basic sight angle.

Speed Ratio: The term speed, such as one-speed or 36-speed, is used to indicate the ratio between a dial or shaft and the basic quantity with which it is associated. It has no relation to the sense of velocity. A clock, for example, measures the rotation of the earth. The small hand makes two revolutions per day, and thus operates at two-speed, while the big hand makes 24 revolutions to one revolution of the earth, operating at 24-speed.

Thus, if a torpedo course dial or shaft turns at one-speed, it makes one complete revolution for each 360 degrees of torpedo course. If the dial or shaft operates at 36-speed, it makes 36 revolutions for each revolution of the one-speed dial or 360 degrees. Therefore, one revolution of the 36-speed, dial or shaft represents 10 degrees.

 
3

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
In this manual the term speed will also be used in relation to the sense of velocity. Thus, in the term target speed or torpedo speed, speed means the velocity of the target or the torpedo and is usually expressed in knots.

COMPUTING LATITUDE CORRECTION

Latitude correction, Kla, is calculated and introduced, as a hand input, in the Torpedo Director Mk 27 Mods 1 to 9.

Several U. S. Navy publications develop the theory which underlies gyroscopic creep and latitude correction. One particular publication is OP 627 (A), "U. S. Navy Torpedo Gyroscopes, Non-Tumble Type". For the present purpose, it is sufficient to state that when the latitude in which torpedoes are fired differs from that for which the gyro balance nuts are set, a latitude correction to sight angle should be applied.

Either formula (1) or formula (2) given below should be used, as appropriate, to calculate the latitude correction

Kla = (0.0037 X R X (Sin L2-Sin L1)) / Sto (1)

or

Kla = (0.0037 X R X (Sin L2+Sin L1)) / Sto (2)

where Kla = latitude correction in degrees
R = =torpedo run in yards

  L2 = firing latitude
L1 = balance latitude
Sto = torpedo speed in knots

Note: When L2 and L1 are on the same side of the equator, formula (1) applies; when L2 and L1 are on opposite sides of the equator, formula (2) applies.

The latitude correction, Kla is read on the outer dial of the intercept offset dial group against a fixed index and is introduced into the director in two steps

(1) By turning the latitude correction hand knob adjacent to dial group; each click of the hand knob represents one-sixth degree (ten minutes) correction. If L2 is north of L1, set the computed correction in the direction of the "N" as marked on the dial. This is equivalent to indexing the tube to the left and corrected sight angle will read less than basic sight angle. If L2 is south of L1, set the correction in the direction of "S" on the dial. This is equivalent to indexing the tube to the right and corrected sight angle will read more than basic sight angle.

(2) By turning the intercept offset hand crank. Rotation of this crank positions the inner dial of the intercept offset dial group. Since the intercept offset index on the ring dial is moved in setting latitude correction, it is always necessary to set intercept offset after latitude correction is set. If no offset is used, reset the inner dial to zero.

 
4

Chapter 2

INTRODUCTION
 

This manual describes the operation, installation, repair, and maintenance of the Torpedo Director Mk 27 Mods 1 to 9, the Torpedo Course Indicator Mk 1 Mods 0 to 4, the Telescope Mk 50 Mods 0 and 1, and the Firing Key Mk 19 Mods 0 and 1. The construction and description of the Torpedo Director Mk 27 Mods 4 and 5 are covered in detail, but only the differences of the other mods from the Mods 4 and 5 are   given.

The torpedo fire control problem and how the torpedo director solves this problem to supply torpedo course and gyro angle is also described. A typical torpedo fire control system installed on a modern destroyer is explained in this manual to show the application of the director and related torpedo fire control mechanisms. See figure 3.

Photo of destroyer showing location of torpedo director,
torpedo course indicator and bench mark.
Figure 3-View of modern destroyer showing location of torpedo director, torpedo course indicator and bench mark.
 
5

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Front right photo of Torpedo Director.
Figure 4-Front right view of Torpedo Director Mk 27 Mod 5.

What the Instruments Are

The torpedo director, see figure 4, is a fire control instrument which computes torpedo course relative) and transmits electrical torpedo course orders and gyro angle orders to the torpedo course indicators at the torpedo tube mounts. A firing key at the director when closed completes the firing circuit which launches the torpedo on its run to the target.

Where the Instruments Are Used.

The torpedo director and the torpedo course indicators are used in the torpedo fire-control

 

Front left photo of Torpedo Director.
Figure 5-Front left view of Torpedo Director Mk 27 Mod 5.

system of modern destroyers. On destroyers having only one director, the director is mounted on the centerline of the signal bridge forward of the Gun Director Mk 37. When two torpedo directors are used, they are mounted in the wings of the signal bridge, one on the port and one on the starboard side. A torpedo course indicator is mounted on each of the torpedo tube mounts. See figure 3.

What the Instruments Do

The Torpedo Director Mk 27 produces, by electrical and mechanical means, torpedo

 
6

INTRODUCTION
 
course and transmits torpedo course orders and gyro angle orders electrically to the torpedo course indicators. See figure 11. At the torpedo tube mount, the torpedo tubes are trained until the torpedo course and gyro angle dials of the indicators are matched. When these dials are matched, the tubes are trained correctly and actual tube train can be read directly from the tube train dial of the torpedo course indicator.

In actual operation, the torpedo director mechanically computes basic sight angle from the torpedo-speed triangle, corrects it for torpedo creep (latitude correction) and then combines the corrected sight angle with relative target bearing to produce basic torpedo course. The basic sight angle can be modified at the director to change the point of intercept without changing the problem set-up. The basic torpedo course can also be modified at the director for tube offset to produce torpedo course.

The tube offset provides a spread angle between the two torpedo tube mounts on the ship and should not be confused with the spread gyro angle set on the torpedoes of a given tube mount.

Synchro generators in the torpedo director continuously transmit (electrically) torpedo course at one-and 36-speed and gyro angle at two-speed to the torpedo course indicators at the torpedo tube mounts. Dials at the torpedo director show the values of all the quantities entering in the torpedo fire control problem and the values of torpedo course and gyro angle transmitted to the torpedo course indicators.

The torpedo course and gyro angle signals are received by synchro motors in the torpedo course indicators. These motors position the inner dials of follow-the-pointer dial groups. The gyros in the torpedoes are set properly by turning the basic-gyro-setting hand crank at the tube mount until the gyro angle dials are matched. The torpedo tube mount is properly trained by turning the training hand crank at the torpedo tube mount until the one-and 36-speed torpedo course dials are matched. The torpedo tubes are correctly aimed when the torpedo course and gyro angle dials are matched with the signals transmitted from the torpedo director.

  HOW THE DIRECTOR SOLVES THE TORPEDO FIRE TRIANGLE

Basically, the job of the director is to solve or produce the required relative torpedo course for firing torpedoes to hit the target. As shown in figure 146, torpedo course (relative) depends upon two quantities: (1) relative target bearing and (2) basic sight angle corrected for

Photo of Torpedo Course Indicator installed on torpedo course attachment, quintuple tube mount.
Figure 6-Torpedo Course Indicator Mk 1 Mod 4 installed on torpedo course attachment, quintuple tube mount.

Photo of Telescope.
Figure 7-Telescope Mk 50 Mods 0 and 1.

 
7

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 

Photo of Firing Key
Figure 8-Firing Key Mk 19 Mod 0.

latitude correction. Of these quantities, basic sight angle is the only unknown one, therefore, the director must solve for this basic sight angle before torpedo course can be determined.

Theoretically, the problem involved is to solve the triangle of torpedo fire.* See figure 9. In this triangle, the line of sight from own ship to target forms the base of the triangle. The length of this line is proportional to the range of the target. The target track and torpedo track form the other two sides of the triangle. Since the lengths of torpedo track and target track are proportional to the torpedo and target speeds respectively, these lines may be considered as representing torpedo and target speeds. Therefore, for a given target angle, the torpedo will intercept the target at point M. (This occurs, as shown in figure 9, when Xt (target deflection) is equal to Xto (torpedo deflection).

Xt = St Sin Bt
Xto = Sto Sin Ds
Thus, to secure a hit, Xt must equal Xto, when St Sin Bt Sto Sin Ds. From the above equation, Ds (basic sight angle) can be found, since the three remaining quantities (St, Bt and Sto) are known.

The torpedo director handles the problem in the form of the equation given above. Basic

  sight angle is computed in the director by the operation of the two component solvers, front and back, see figure 10. The front solver (target solver) from inputs of target course, target speed, own ship course and relative bearing produces Xt (target deflection component). The back solver (sight angle solver), with an input of torpedo speed, is rotated through an angle of Ds (sight angle) by the sight angle follow-up motor or the sight angle hand crank, until its output Xto (torpedo deflection) equals Xt. When Xt equals Xto, the high-and low-speed zero reader dials in the torpedo director are at zero. If these dials are off, they indicate that the Xt and Xto are not equal and that the correct sight angle has not been produced. For a more detailed description of how the torpedo director works, see chapter 3.

*To simplify the explanation and understanding of the torpedo fire-triangle problem, gyro angle, latitude correction, intercept offset and tube offset were omitted. However, in actual solution of the problem in the torpedo director, these quantities are taken into consideration in producing torpedo course orders.

INPUTS AND OUTPUTS

The Torpedo Director Mk 27 has two electrical inputs, ten hand inputs, and two electrical outputs. See figure 146.

Electrical Inputs

One electrical input received by the director is own ship course (Co). It is received continuously at one-speed from the gyro compass system, and positions the one-speed own ship course zero reader dial. In case of power failure, own ship course can be introduced into the director by hand, see Hand Inputs below.

The other electrical input, relative target bearing (Bs), is received at one-and 36-speed by the bearing receiver on the right side of the torpedo director. This electrical signal positions the inner dials of the one-and 36-speed follow- the-pointer dial group of the bearing receiver. The ring dials of the two dial groups are turned mechanically to match the inner dials by manually rotating the training handwheel of the torpedo director.

 
8

INTRODUCTION
 
Hand Inputs

The 11 hand inputs to the torpedo director are:

(1) Own ship course (Co) is introduced by hand at 180-speed or 2 degrees per revolution of the hand crank. This quantity is introduced manually when there is power failure to the servo motor of the own ship course follow-up unit. In this case, the own ship course hand crank is turned to keep the zero reader dial matched at zero.

  (2) Target speed (St)is introduced by hand at 10-speed or 2 knots per revolution of the hand crank. The director personnel receive this quantity by telephone from the ship's main plot or CIC. This quantity positions the speed spiral of the front solver (target solver). The target speed dial indicates the amount set into the director.

(3) Target course (Ct) is set in by hand at 90-speed or 4 degrees per revolution of the hand crank. The director operators also receive this quantity

Drawing showing the triangle of torpedo fire defining all the angles.
Figure 9-The triangle of torpedo fire.
 
9

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Diagram of computer angle solver position.
Figure 10-Diagram of computer angle solver position after computing fire control problem.
 
10

INTRODUCTION
 
by telephone from the ship's main plot or from CIC. The target course input positions the angle gear of the front solver and the target angle dial.

(4) Torpedo speed (Sto) is introduced by hand at 10-speed or 2 knots per revolution of the hand crank. This is an arbitrary speed chosen for the torpedo problem set-up. The director is designed to solve for torpedo speeds from 0 to 50 or 60 knots. This quantity positions the speed spiral of the back solver and the torpedo speed dial.

(5) Torpedo course (relative) (Bto) is produced in the director by turning the training handwheel at 180-speed or 2 degrees per revolution for Mods 1, 2, 3, and 7 and at 120-speed or 3 degrees per revolution of the handwheel for Mods 4, 5, 8, and 9. Rotation of the handwheel positions the torpedo course synchro generators and the director computing mechanism.

(6) Relative Target Bearing (Bs) (director train plus sight angle) is introduced manually by turning the director train handwheel until the inner follow-the-pointer dials of the bearing receiver are matched. Relative target bearing can be obtained optically by training the director until the telescope bears on the target.

(7) Latitude Correction (Kla) is introduced by hand at 180-speed or 2o per revolution of the knurled latitude correction wheel. One click equals 10 minutes. The magnitude of the correction depends upon the duration of the torpedo run and the latitude in which the torpedo is fired. The latitude correction dial indicates in degrees the amount of the correction introduced in the director.

(8) Intercept offset (Osi) is introduced by hand at 180-speed or 2 degrees per revolution of the hand crank. This input, an arbitrary correction, is introduced when it is desired to change the basic sight angle by some pre-determined value to take care of unexpected target maneuvers. The changes are made in the basic sight angle directly without altering the problem set-up. Intercept offset is generally introduced after one or more torpedoes have been fired. The intercept offset dial indicates the amount of offset introduced in the director.

  (9) Tube offset (Otu) is introduced by hand at 180-speed or 2 degrees per revolution of the hand crank. Tube offset modifies the torpedo course order so that the forward tube mount is trained forward and the after tube mount is trained aft, or vice versa through an angle equal to the tube offset angle with respect to the basic torpedo course. The tube offset dial indicates in degrees the amount of offset introduced in the director.

(10) Gyro angle (Bgy) is introduced by hand at 72-speed or 5 degrees per revolution of the hand crank. This input positions the gyro angle dial and the two-speed synchro generator marked "E". This generator transmits gyro angle electrically at two-speed to the torpedo course indicator at the forward and after torpedo mounts.

(11) Sight angle (Ds) is introduced by hand at 180-speed or 2o per revolution of the hand crank. This quantity is introduced manually when there is power failure to the sight angle servo motor. In this case the hand crank is turned to keep the high-and low-speed zero reader dials at zero.

Outputs

The two electrical outputs of the torpedo director are:

(1) Torpedo course order (Bto) transmitted at one-and 36-speeds by the two sets of synchro generators. The generator "C" and the generator "A" transmit one-and 36-speed signals respectively to the torpedo course indicator on the forward torpedo tube mount, generators "B" and "D" transmit torpedo course to the after torpedo tube mount. See figure 146.

(2) Gyro angle (Bgy) is also transmitted to the torpedo course indicators at the torpedo tube mounts. It is transmitted at two-speed by the synchro generator "E".

Note: When the operators at the tube mounts turn their hand cranks to match the torpedo course dials and the gyro angle dials of the torpedo course indicators, they train the mounts correctly to hit the target and thus produce tube train.

 
11

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Table I

DIFFERENCES BETWEEN MODIFICATIONS OF THE TORPEDO DIRECTOR MK 27

Mod Maximum Torpedo Speed Number of sets of one-and 36-speed Torpedo Course Synchro Generators Training Handwheel Speed Type of Bearing Receiver Used Remarks
1 50 knots 2 sets 180-speed 2o/Rev. External lighting type (ORDALT 2107)  
2 50 knots 3 sets 180-speed 2o/Rev. External lighting type (ORDDALT 2107) No tube offset provided for set of torpedo course generators controlling center torpedo tube mounts. Construction same as Mod 1.
3 60 knots 2 sets 180-speed 2o/Rev. External lighting type (ORDALT 2107) Construction same as Mod 1.
4 60 knots 2 sets 120-speed 3o/Rev. External lighting type (ORDALT 2107) Similar in appearance and construction to Mod 1. For description of bearing receiver see pages 54 to 61.
5 60 knots 2 sets 120-speed 3o/Rev. External lighting type (ORDALT 2107) This is the production instrument. Similar to Mod 4. For bearing receiver see pages 54 to 61.
6 60 knots 2 sets 120-speed 3o/Rev. None Experimental director, only one manufactured. Same as Mod 5 except contains square race dial gears.
7* 50 knots 2 sets 180-speed 2o/Rev. Internal lighting type Mod 1 torpedo director with a bearing receiver attached, see pages 54 to 61.
8* 60 knots 2 sets 120-speed 3o/Rev. Internal lighting type Mod 4 torpedo director with a bearing receiver attached, see pages 54 to 61.
9* 60 knots 2 sets 120-speed 3o/Rev. Internal lighting type Mod 5 torpedo director with a bearing receiver attached, see pages 54 to 61.

*NOTE: Mods 7, 8, and 9 were assigned after internal lighting type bearing receivers were installed. All ships having these instruments are now in inactive status. Instrument nameplates are to be changed from Mods 1, 4, and 5 to 7, 8, and 9, respectively, by the ship's force at the time the ships are activated.

 
12

INTRODUCTION
 
When tube offset has been set into the director, synchro generators "A" and "C" send out torpedo course modified for tube offset for the forward tube mount; synchro generators "B" and "D" transmit torpedo course modified for tube offset for the after tube mount.

DIFFERENCES BETWEEN MODS OF TORPEDO DIRECTOR

The Torpedo Directors Mk 27 Mods 1 to 9 are similar in purpose, function, and operation. They all require the same type of inputs and all have the same outputs, torpedo course, and gyro angle. The main differences between the various mods are: (1) the maximum torpedo speed that can be set in the director, (2) the number of sets of one-and 36-speed torpedo course synchro generators, (3) the speed of the training handwheel and telescope drive and (4) the type of bearing receiver used. The main differences between the various mods of the torpedo director are listed in table 1, page 12.

NavOrd Ordalts Applicable

1255-Instructions for installing centering device for sight angle motor follow-up.

  1787-Installation of red illumination for dials.

2107-Installation of relative target bearing receiver.

DIFFERENCES BETWEEN MODS OF THE TORPEDO COURSE INDICATOR

The Torpedo Course Indicator Mk 1 Mods 0 to 4 are somewhat similar in design, purpose, and function. All the instruments have dials which indicate torpedo course at one-and 36speed, torpedo course order at one-and 36speed, gyro angle and gyro angle order at two-speed, except Mod 3, and tube train at one-speed.

The major difference between the various mods are: (1) the type of supply used for dial illumination (separate six-volt supply or six-volt supply from transformer in instrument), (2) the number of synchro motors used, (3) the type of gyro angle dials used, (4) the use of plug boards in the lightwell wiring, and (5) the use of a three-ampere fuse in the lightwell wiring. These differences are summarized in table 2, page 13 for the various mods of the torpedo course indicator.

Table 2

DIFFERENCES BETWEEN MODS OF THE TORPEDO COURSE INDICATOR MKI MODS 0 TO 4

Instrument Number of synchro motors Receives gyro angle order electrically Has separate six-volt dial illumination supply Has dial illumination transformer Has plug board in lightwell wiring Has three-ampere fuse in lightwell wiring
Mod 0 3 yes no yes yes no
Mod 1 3 yes no yes no no
Mod 2 (original) 3 yes no yes no yes
Mod 2 (later) 3 yes yes no no no
Mod 3* 2 no no yes no yes
Mod 4 3 yes yes no no no

*The major difference between the Mod 3 and the other indicators is that the Mod 3 is not provided with the two-speed gyro angle synchro motor and the gyro angle follow-the-pointer dials. In the Mod 3, the follow-the-pointer dials are replaced with a single gyro angle dial which indicates gyro angle in degrees set into the gyros of the torpedoes.

735193-47-2

 
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TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Functional diagram showing course of inputs and outputs through the Torpedo Course Indicator.
Figure 11-Functional diagram showing course of inputs and outputs through the Torpedo Course Indicator Mk 1 Mods 0, 1, 2 and 4.
 
14

Chapter 3

FUNCTIONAL DESCRIPTION
 

HOW THE TORPEDO DIRECTOR MK 27 WORKS

In this section, the overall internal operation of the Torpedo Director Mk 27 Mods 1 to 9 is described. For information on how each individual unit of the torpedo director works, refer to the particular section describing the unit in the Description Chapter.

Figure 146, functional diagram for the torpedo director, shows the path of the various quantities through the torpedo director. In order to simplify the description of how the director works, each quantity will be discussed to show its travel through the director and what part it contributes in producing torpedo course.

Relative Target Bearing

This quantity is received electrically by the one-and 36-speed synchro motors in the bearing receiver. As shown in figure 146, this quantity positions the inner dials of the follow-the-pointer dial groups. To get the director on the designated target, these dials are matched against the ring dials by turning the training handwheel.

If all the dials of the director are set at zero, rotation of the training handwheel will: (1) train the director case and the telescope as a unit, (2) position the middle dial of main dial group "A" via differential DF-3 to indicate relative target bearing, (3) position the rotors of two sets of one-and 36-speed torpedo course synchro generators an amount equal to relative target bearing, and (4) position the torpedo course dials to indicate this bearing.

In actual operation, this is not the case. Briefly, the input of relative target bearing, introduced by the training handwheel, is combined with corrected sight angle and tube offset to produce the torpedo course necessary to hit the target. Therefore, before the correct torpedo course can be produced, all the necessary

  quantities or known factors of the torpedo control problem must be introduced into the torpedo director.

Own Ship Course

This quantity, received electrically at one-speed, positions the own ship course zero reader dial. In normal operation, rotation of the rotor of the own ship course synchro motor operates the follow-up mechanism which controls the operation of the servo motor. Rotation of the servo motor, positions the own ship course dial and sends own ship course (Co) to differential DF-2. Here, own ship course is combined with relative target bearing (Bs) to produce true target bearing (B).

For a complete description of how the own ship course receiver works, see page 45.

True target bearing positions the outer ring dials of the main dial groups "A" and "B" and goes through differential DF-2.

Target Speed

The target speed crank is turned to introduce the proper target speed in the torpedo director. Rotation of this crank does two things: (1) it positions the target speed dial which indicates the amount of target speed set in, and (2) positions the speed gear (spiral-cam plate) of the front solver. Rotation of the spiral plate positions the pin (cam follower) away from the center of the plate, a distance proportional to target speed. The intermittent gear limit stop limits target speed input from 0 to 50 knots.

Target Course and Target Angle

Target course (Ct) is introduced into the director by rotation of the target course knob. This input goes to differentials DF-1 and DF-2 where it is combined with true target bearing to produce target angle (Bt).

 
15

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Target angle positions the middle dial of the main dial group "A" and the angle gear of the front solver. Rotation of the angle gear drives the output rack, by means of the pin, to produce target deflection (Xto) which goes to differential DF-6.

Target angle also positions the spiral gear via the compensating differential DF-4. The purpose of this differential is to prevent the position of the pin from changing as the angle gear is rotated. For a complete description of the component solver and the compensating differential, see page 35.

Torpedo Speed

The torpedo speed crank is turned to introduce, through DF-5, the proper torpedo speed (Sto) into the torpedo director. Rotation of this crank does two things: (1) it positions the torpedo speed dial which indicates the amount of torpedo speed set in, and (2) it positions, through DF- 5, the speed gear (spiral-cam plate) of the back solver. Rotation of the spiral plate positions the pin (cam follower) away from the center of the plate a distance proportional to torpedo speed.

The limit stop limits torpedo speed input from 0 to 50 knots for Mods 1, 2, and 7 and from 0 to 60 knots for Mods 3, 4, 5, 6, 8 and 9.

Torpedo Deflection and Target Deflection

Assuming that the angle gear of the back solver is at its zero position, the output of the solver, torpedo deflection (Xto) would be zero. If it were at any other position a certain amount of torpedo deflection would be produced. This quantity Xto is sent to differential DF-6 where it is compared with target deflection (Xt). If both quantities are equal, there is no output of the differential and the high-and-low-speed zero reader dials remain zeroed.

If the two quantities are unequal, the differential algebraically adds the two quantities to form an output. This output does two things: (1) it displaces the zero reader dials from their zero position, and (2) it operates the follow-up mechanism which controls the sight angle servo motor (telescope train motor) which restores

  the zero-reader dials to zero. In other words, the algebraic sum of Xt and Xto equals zero.

Sight Angle

Rotation of the sight angle servo motor produces sight angle which does three jobs: (1) sight angle via differential DF-9 trains the telescope away from the target an angle equal to the sight angle, (2) positions the basic sight angle dials, and (3) positions the angle gear of the back solver, until a value of Xto is produced that is equal to Xt. When Xto equals Xt, the follow-up mechanism is zeroed and the servo motor stops rotating.

Note: In case of power failure to the servo motor, the sight angle hand crank can be used to take the place of the servo motor. In this case, the crank must be turned to keep the high-and-low-speed zero reader dials zeroed.

The limit stop switch shown in figure 35, controls the operation of the servo motor when sight angle is at its extreme limits.

Torpedo Course

Torpedo course is produced when the director trainer turns the training handwheel to bring the telescope back on the target. Rotation of the handwheel positions the rotors of the two sets of one- and 36-speed torpedo course synchro generators, the torpedo course dials, and the check dials.

This torpedo course does not include latitude correction, intercept offset or tube offset. These corrections are introduced into torpedo course as follows:

Latitude Correction

Latitude correction is produced when the latitude knob is turned to set the latitude correction dial. The correction is introduced in the instrument, when the intercept offset crank is turned to match the intercept dial with the latitude correction dial.

Intercept Offset

When the intercept offset crank is turned to introduce either latitude correction or intercept offset, it trains the telescope via differential

 
16

FUNCTIONAL DESCRIPTION
 
DF-9 an additional amount equal to the correction and also positions the front and back solvers. Thus, differential DF-9 combines basic sight angle with this correction to produce corrected sight angle.

Corrected Sight Angle

This corrected sight angle trains the telescope, and positions the corrected sight angle dial and the inner dials of the main dial group "A" and "B"

Here again, when the training handwheel is turned to bring the telescope back on the target, the torpedo course corrected for latitude correction and intercept offset is produced.

Tube Offset

Tube offset is introduced when the tube offset crank is turned. Rotation of the crank positions the tube offset dial and is transmitted to differentials DF-7 and DF-8 where torpedo course is modified for tube offset. The outputs of DF- 7 and DF-8 position the torpedo course synchro generators which transmit the torpedo course corrected for tube offset to the torpedo course indicators.

Gyro Angle

Gyro Angle is produced when the gyro angle crank is rotated to position the gyro angle dials. Rotation of the crank is transmitted to position the rotor of the gyro angle synchro generator. This generator transmits gyro angle electrically at two-speed to the torpedo course indicators.

In actual operation of the torpedo director, several of the above operations are going on at the same time. Therefore, torpedo course is being produced continuously by the torpedo director as the problem progresses.

HOW THE TORPEDO INDICATOR MK I WORKS

The Torpedo Course Indicators Mk 1 Mods 0 to 4 are similar in purpose and operation. Each indicator is secured to a torpedo course attachment which is mounted on the top of the torpedo tube mount. See figure 6.

  The purpose of the torpedo course indicator is to enable the tube mount personnel to train the tube mount and set the gyro angle on the torpedoes in accordance with the electrical torpedo course and gyro angle orders from the director.

Inputs

The indicator has four inputs: (1) torpedo course received electrically at one- and 36-speed, (2) gyro angle received electrically at two-speed, (3) tube train received mechanically at 18-speed and, (4) gyro angle received mechanically at 36-speed. See figure 11.

The indicator is equipped with dials to show torpedo course, gyro angle, and tube train.

The Torpedo Course Indicator Mk 1 Mod 3 is equipped with only two synchro motors which receive torpedo course. The Mod 3 indicator does not receive gyro angle electrically.

Figure 11, functional diagram of the Torpedo Course Indicator Mk 1 Mods 0, 1, 2, and 4, illustrates the path of inputs through the instrument.

1. Torpedo course received electrically at one- and 36-speed, positions the inner dials of the torpedo course follow-the-pointer dials.

2. Gyro angle received electrically at two-speed positions the inner dial of the gyro angle follow-the-pointer dial.

3. Gyro angle received mechanically at 36speed from the gyro setting mechanism performs two actions: (1) it positions the ring dial of the gyro angle follow-the-pointer dials to match the inner dial, and (2) it forms one input to the differential. When the gyro angle dials are matched the gyros in the torpedoes are properly set.

4. Tube train received mechanically at 18speed from the tube mount rack as the mount is trained, also results in: (1) positioning the tube train dial to indicate the actual train of the tube mount, and (2) forming the other input to the differential. The differential algebraically adds gyro angle to tube train to produce torpedo course.

Torpedo course, output of the differential, mechanically positions the ring dials of the

 
17

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Illustration of Torpedo Course Indicator dials
Figure 12-Appearance of Torpedo Course Indicator dials alter torpedo course and gyro angle orders have been received from the torpedo director.
Illustration of Torpedo Course Indicator dials.
Figure 13-Appearance of Torpedo Course Indicator dials after tube mount has been trained to execute torpedo course order and gyro angle has been properly set on torpedoes.
 
18

FUNCTIONAL DESCRIPTION
 
torpedo course follow-the-pointer dials to match the inner dials. When the torpedo course dials are matched, the torpedo tube mount is properly trained. See figure 13. To operate the indicator properly the gyro angle dials and the torpedo course dials must be kept matched at all times in order to launch the torpedoes on the correct course.

How to Read the Dials of the Indicator

The Torpedo Course Indicator Mk 1 Mods 0, 1, 2, and 4 is equipped with three sets of dials: (1) the one- and 36-speed torpedo course follow-the-pointer dials, (2) gyro angle follow-the-pointer dials, and (3) the tube train dial.

The Torpedo Course Indicator Mk 1 Mod 3 is also equipped with three sets of dials. However, unlike the other mods the gyro angle dial is a single mechanically driven dial that indicates the amount of gyro angle set into the torpedoes.

Torpedo Course Dials. The torpedo course dials consist of an inner dial, positioned by torpedo course received electrically from tie torpedo director, and a ring dial positioned mechanically by the output of the differential in the torpedo course indicator.

Figure 12 illustrates how the dials appear when the torpedo course indicator is receiving a typical torpedo course order from the director. Observe that the inner dials have moved away from their zero position and that their indexes are not in alignment with the indexes of the ring dials. This indicates that the torpedo tube mount has not been trained to carry out the order.

Figure 13 illustrates how the dials appear when the torpedo tube mount has been trained to execute the torpedo course order. The indexes of the ring dials match the indexes of the inner dials. The ring dials when read against the fixed indexes show that the torpedo course order received from the torpedo director is 126 degrees. As illustrated, the one-speed dial indicates approximately "120" degrees and the 36speed dial indicates "6" degrees. Therefore, the exact reading is 126 degrees.

Gyro Angle Dials. The gyro angle dials of the Torpedo Course Indicator Mk 1 Mods 0, 1,

  2, and 4 consist of an inner dial, positioned by gyro angle order, received electrically from the torpedo director, and a ring dial positioned mechanically by the basic gyro setting hand crank.

Figure 12 illustrates appearance of the dials when the indicator is receiving a typical gyro angle order from the torpedo director. Observe that the inner dial is away from its zero position and that the index of the inner dial is not in alignment with the index of the ring dial.

Figure 13 shows how the dials appear when the basic gyro setting hand crank has been turned to match the index of the ring dial with the index of the inner dial. When the dials are matched, the gyros are properly set in the torpedoes. The reading of the ring dial against the fixed index indicates the gyro angle is 16 degrees.

The single gyro angle dial of the Mod 3 indicator is positioned mechanically by the rotation of the basic gyro angle hand crank of the gyro setting mechanism. The graduations on this dial are the same as those on the gyro angle dial for Mods 0, 1, 2, and 4. The Mod 3 dial indicates in degrees the gyro angle set on the gyros in the torpedoes.

Tube Train Dial. This dial is positioned mechanically, degree for degree, as the torpedo tube mount is trained. The tube train dial indicates the actual train of the torpedo tube mount relative to own ship.

Figure 13 illustrates the appearance of the dial when the torpedo tube mount is trained 110 degrees.

HOW THE TELESCOPE MK 50 WORKS

The main purpose of the telescope is to enable the director trainer to train the director on a visible target and to keep the director trained on the target as corrected sight angle is being produced in the director. See figure 7.

The Telescope Mk 50 Mod 0 and 1 is of the tilting mirror type. As the ship rolls and pitches the line of sight is kept on the target by means of the mirror elevating knob which positions the mirror in the telescope. Figure 14 is a schematic diagram of the telescope. This view shows the path of light through the lens system.

 
19

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
The ray filters in the telescope are shifted by rotation of the ray filter knob mounted on the top of the telescope. The ray filters provided are "CLEAR", "RED", "YELLOW", "LIGHT NEUTRAL", and "DARK NEUTRAL". The crosslines of the telescope are illuminated by   means of a lamp. The intensity of the crossline illumination is controlled by the crossline illumination rheostat mounted on top of the torpedo director case. This rheostat provides for three conditions "DIM", "OFF", and "BRIGHT".
Telescope Mk 50 optical diagram.
Figure 14-Telescope Mk 50 optical diagram.
 
20

Chapter 4

OPERATION
 

The operation procedure and related information presented in this chapter are compiled from current standard destroyer doctrine and should serve as a guide which can be varied according to type of ship, personnel available, material conditions and the ship's doctrine set down by the ship's commanding officer.   PERSONNEL REQUIRED

Theoretically, the Torpedo Director Mk 27 Mods 1 to 9 can be operated by two men, but in actual operation three or four men are used. They are: (1) torpedo officer, (2) director trainer, (3) selector switch operator, and (4) telephone talker. See figure 15.

Torpedo officer, director trainer and telephone talker operating torpedo director.
Figure 15-Torpedo officer, director trainer and telephone talker operating torpedo director.
 
21

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Torpedo Officer

The torpedo control officer is responsible, under the commanding officer, for the efficient operation and maintenance of the torpedo control system and the torpedo battery. The torpedo control officer will see that firing and synchro transmission circuits are tested frequently. His station is at the engaged torpedo director. He is usually free to consult with the commanding officer concerning favorable track angles, unmasking the battery, and torpedo speed settings. When firing torpedoes from both sides of the ship, by utilizing both torpedo directors, the officer of the deck and the director trainer man one torpedo director and the torpedo control officer and the selector switch operator man the other.

When the target is designated by the commanding officer, the torpedo officer's usual duties are:

1. Orders "Torpedo action port (starboard)". Designates the target and approximate bearing to the director trainer and tube personnel.

2. Orders type of fire, bridge control or local control. Director control is further indicated by order, "Match pointers".

3. Orders depth setting in feet.

4. Informs director trainer and tube personnel of number of torpedoes in spread, torpedo speed, unit of spread, and tube mount offset.

Note: Speed setting is the commanding officers decision.

5. Informs director trainer of target course and speed.

6. Informs tube personnel of target angle and speed.

7. Checks tube train and gyro angle to insure firing on safe bearing and maintains control of gyro angle at the director. Note: The torpedo officer must know the gyro angle setting so that he can select the proper intercept offset and torpedo speed corrections.

8. Orders re-adjustment, if necessary, for director set-up.

9. Makes sure that the target is within the effective range.

10. Reports, "On target", to commanding officer. When directed by commanding officer,

  orders "stand-by" then "Fire one", "Fire two", etc.

11. Orders "Selective aim, right to left (left to right)" so the director trainer can choose firing points in the order given. In addition to the above, he also keeps the tube personnel informed of:

1. The relative bearing and appearance of the target.

2. The target angle and speed.

Director Trainer

The director trainer mans the torpedo director and its firing key on the engaged director. In actual operation of the torpedo director, the director trainer performs the following duties:

1. Sets torpedo speed, target speed, and target course into the torpedo director.

2. He trains the torpedo director on the target by looking through the telescope and turning the training handwheels until the crosslines bear on the target. He can also train the director on an invisible target by turning the training handwheel to match the dials of the bearing receiver.

3. Sets gyro angle into the torpedo receiver as ordered.

4. Makes any other setting or correction as directed.

5. Makes reports such as: "Director set"; "On target" or "On radar bearing"

6. Fires torpedoes with firing key as directed with three second intervals.

Selector Switch Operator

The selector switch operator, at the director, operates the selector and firing switches. He operates own ship course hand crank in case of power failure. The following duties are performed by the selector switch operator:

1. Maintains immediate contact over the telephone with the torpedo tube mount operators.

2. Relays, by telephone, target designation, target angle, target speed, torpedo speed, depth setting, unit of spread, and tube offset to the torpedo tube mounts.

3. Informs the tube mount operators of the number of torpedoes in salvo.

 
22

OPERATION
 
4. Operates selector firing switches, reporting by telephone, to the tube mounts, "Fire one, fire two", etc.

Telephone Talker

Serves as torpedo control officer's talker and performs duties of trainer and selector switch operator in case of casualties to personnel.

For a complete description of the duties of the various operators used in the torpedo control system, see current D.T.B. (confidential) "Destroyer Torpedo Doctrine and Manual of Torpedo Control".

HOW TO READ THE DIALS OF THE TORPEDO DIRECTOR

To simplify the understanding of the dial readings and what they represent, a typical torpedo control problem is given below. Dial readings are illustrated and an explanation of the values they represent in the torpedo control problem is given.

For example, take the problem of a destroyer, which is on course 40 degrees when an enemy ship is sighted at a range of approximately 6,000 yards. The estimated target course and speed are 210 degrees and 30 knots respectively. See figure 16. The torpedo control officer orders tube mount personnel to "Standby" for curved fire with a spread gyro angle of 4 degrees between torpedoes.

He also may decide to use a 30 degrees gyro angle, a 10 degrees tube offset and a torpedo speed of 40 knots. These values are immediately cranked into the starboard torpedo director by the director trainer.

The director trainer also cranks into the torpedo director the target course (210degrees) and the target speed (30 knots) as relayed to him by the torpedo control officer.

Main Dial Groups

Figure 17 illustrates the torpedo problem as it now appears on the main dial groups. The fixed straight line joining the centers of the main dial groups represents the line of sight. Both outer ring dials have a zero degree graduation which indicates true north. These dials

  are positioned by true target bearing. Note: True target bearing is made up of own ship course and relative target bearing. The outer ring dial of the dial groups "A" when read against the fixed index indicates the true target bearing. In this case, the dial indicates a true target bearing of "90 degrees", that is, the angle between the north and the line of sight to the target, measured clockwise from the north.

Illustration of typical torpedo problem.
Figure 16-Typical torpedo problem.

 
23

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
Main dial group of torpedo director showing target main dial and own ship main dial.
Figure 17-Main dial group of torpedo director.
 
24

OPERATION
 
The middle ring dials of dial groups "A" and "B" have the outline of a ship engraved on them. When the middle ring dial zero index (bow of ship) of the dial group "A" is read against the outer ring dial, it indicates own   ship course; "40 degrees" for this set-up. When the middle dial is read against the fixed index, it indicates a relative bearing of "50 degrees". When the zero index of the middle ring dial of the "B" group is read against the outer ring dial, it
Appearance of tube offset and tube dials.
Figure 18-Appearance of tube offset and tube dials.
 
25

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
indicates a true target course of "210 degrees". When this middle dial is read against the fixed index it indicates a target angle of "60 degrees".

The center dials of the dial groups "A" and "B" are positioned mechanically by the corrected sight angle that is produced within the director. Note: Corrected sight angle cannot be read directly from these dials, but it can be obtained by reading the sight angle dials, see figure 22. The center dial of group "A", when read against the middle ring dial, indicates a relative torpedo course (uncorrected for tube offset of 80 degrees-30'). True torpedo course can be obtained by reading this dial against the outer ring dial. In this case, the reading is 120 degrees-30'. When the center dial of group "B" is read against the middle ring dial, it indicates a track angle of 90 degrees-30'.

Tube Offset and Tube Dials

Figure 18 illustrates the three dial groups to the left of the main dial groups of the torpedo director. The upper dial, the tube offset dial, indicates a reading of "10 degrees" tube offset (starboard) as ordered by the torpedo control officer. The remaining dial groups are for the tubes. The upper group is for the forward torpedo tube mount and the bottom group is for the after torpedo tube mount. The center dial of

  each of these groups is a fixed dial and serves as an index for the middle or gyro angle dial.

The middle dial is positioned mechanically by the gyro angle hand crank and indicates the gyro angle setting to he made on the torpedoes. In this setup, the middle dials when read against the index of the center dial, indicate a reading of "330 degrees". The outer ring dials indicate the torpedo course order transmitted to the torpedo course indicators at the tube mounts. Note: This torpedo course order includes tube offset. Therefore, with a tube offset of 10 degrees (starboard) the torpedo course dial (upper dial group) for the forward torpedo tube mounts reads 70 degrees-30' and the dial for the after torpedo tube mount reads 90 degrees-30'.

Target Speed Dial

The target speed dial, located to the right of the main dial groups, is graduated every knot and numbered every 5 knots from 0 to 50. Figure 19 illustrates the appearance of the dial when 30 knots target speed has been cranked into the director.

Torpedo Speed Dial

The torpedo speed dial, located to the right of the target speed dial, is graduated every knot and numbered every 5 knots from 0 to 60

Target speed dial, 30 Knots Target Speed.
Figure 19-Target speed dial.
  Torpedo speed dial, 40 Knots Torpedo Speed.
Figure 20-Torpedo speed dial.
 
26

OPERATION
 

10 minutes South Latitude Correction.
Figure 21-Latitude correction and intercept offset dial.

40 degrees-40 corrected sight angle, 40 degrees-30 Basic Sight Angle
Figure 22-Corrected sight angle.

  knots. For Mods 1, 2, and 7 the dials are graduated from 0 to 50 knots. Figure 20 illustrates how the dial appears when 40 knots torpedo speed has been introduced.

Intercept Offset and Latitude Correction Dial Group

The above dials, located beneath the target speed dial, consist of an inner and outer dial.

Relative target bearing dials.
Figure 23-Relative target bearing dials.

 
27

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) 1586
 
The outer dial is the latitude correction dial, and the inner ring dial is the intercept offset dial. Figure 21 illustrates the dial readings when 10' south latitude correction and zero degrees intercept offset have been cranked into the torpedo director.

Sight Angle Dials

The sight angle dials, located beneath the torpedo speed dial, consist of an inner and outer dial. The inner dial is positioned mechanically by basic sight angle. The outer dial is positioned mechanically by corrected sight angle. Figure 22 shows how the dials appear when 40 degrees 30' basic sight angle and 40 degrees 40' corrected sight angle have been produced in the torpedo director.

Relative Target Bearing Dials

The relative target bearing dials, located in the bearing receiver, consist of a one- and 36-speed follow-the-pointer dial group. Each set of dials consists of an inner dial, positioned by the electrical target bearing signal, and an outer dial, positioned mechanically to match the inner dial. Figure 23 illustrates the appearance of the dials when the instrument receives a relative target bearing of 50 degrees and the director has been trained to match the order.

  Zero Reader Dials

The zero reader dials, located on the right side of the director case, consist of high- and low- speed dials which are positioned mechanically by the difference between Xt and Xto. When Xt equals Xto, the dials are zeroed as shown in Figure 24. These dials are automatically zeroed by the follow-up mechanism in the director. In case of power failure to the follow-up mechanism, the dials are maintained at zero by turning the sight angle hand crank.

Own Ship Course Dials

The own ship course dials, also located on the right side of the director case, consist of a zero reader dial mounted on the rotor of the own ship course synchro motor and a one-speed dial which is driven mechanically by own ship course gearing in the director. In normal operation, the zero reader dial and the one-speed dial are positioned automatically by the own ship course follow-up unit in the director. In case of power failure to the follow-up unit, the own ship course hand crank must be turned to keep the zero-reader dial continuously matched at zero. Figure 25 illustrates how the dials appear when the torpedo director is receiving an own ship course signal of 40 degrees.

Zero reader dials.
Figure 24-Zero reader dials.
  Own ship course dials.
Figure 25-Own ship course dials.
 
28

OPERATION
 
SOURCE OF INFORMATION FOR INPUTS

The commanding officer informs evaluators in CIC and the torpedo control officer of: (1) target by type and true bearing, (2) number of torpedoes to be fired, (3) torpedo speed setting to be used, and (4) the firing point.

Evaluators in CIC inform both the commanding officer and the torpedo control officers of: (1) best estimate of target course and speed (from information obtained from DRT, main battery plot, radar, and from other sources or the mean value of all sources), (2) present range, (3) estimate of time when target will come within effective range for each torpedo speed, (4) when target comes within effective range at each torpedo speed, (5) when target has gone outside of effective range for each speed, and (6) furnishes relevant corrections for intercept offset and torpedo speed.

Relative target bearing obtained electrically from CIC is indicated on the inner dials of the bearing receiver. The director is trained on the target when the director trainer turns the training handwheel to match the bearing receiver dials. If the target is visible, the director trainer can pick up the target by turning the training handwheel until the vertical crossline of the telescope intersects the target.

Own ship course is received electrically by the torpedo director where a follow-up mechanism converts it automatically into a mechanical input. In case of power failure, the own ship course zero reader dial must be set at zero by means of the own ship course hand crank.

OPERATION ROUTINE

This section will outline a suggested operation routine for putting the torpedo director into operating condition. This routine may vary somewhat with different ships depending upon ship's doctrine. In the following outline, the numbers in parentheses refer to the hand cranks that are numbered correspondingly in figure 147.

1. After removing the tarpaulin cover, set in latitude correction, each morning, by turning the latitude correction knob (1). This can be done by the officer with the morning watch.

75193-47-3

  2. Turn on the power supply to the director and the torpedo control system at the fire control switchboard. Also, turn on the director heater supply.

3. Turn the bridge transfer switch to "PORT" or "STARBOARD".

4. Turn the director selector switch to "ON" and illumination switch to "TRANSFORMER".

The torpedo director is now ready to track a target. In setting up a problem on the torpedo director, the following procedure is suggested:

1. Train the director on the target by turning the training handwheel (2) to match the dials of the bearing receiver or to bring the telescope sight to bear on the target.

2. Set the sight angle crank (3) and the own ship course hand crank (4) to "OUT" position.

Note: In case of power failure, these hand cranks should be left in the "IN" position. As the problem progresses, the own ship course hand crank must be turned to keep the zero reader dial at "0" and the sight angle hand crank must be turned to keep the high and low speed zero reader dials matched at "0".

3. Introduce tube offset by turning the tube offset crank (5).

(4) Introduce refined latitude correction by turning the knob (1) to correct for torpedo creep.

5. Match the intercept offset dial, with the reading on the latitude correction dial by turning hand crank (6). Set intercept offset as necessary to correct for torpedo turning circle when firing shots with large gyro angles.

6. Crank in torpedo speed by turning the torpedo speed hand crank (7).

7. Introduce gyro angle, as directed by the torpedo control officer, by turning the gyro angle crank (8).

8. Introduce target speed by turning the target speed hand crank (9).

9. Set target course into the director by turning the target course hand crank (10). Then train director on target using the telescope sight or by matching the dials of the bearing receiver.

10. Fire the torpedoes, as directed, by closing the firing key (11).

The following procedure is suggested for securing the torpedo director:

 
29

TORPEDO FIRE CONTROL EQUIPMENT (DESTROYER TYPE) OP 1586
 
1. Train the torpedo director to its stowed position, relative bearing

2. Set all the dials of the torpedo director to zero by turning the various hand cranks.

3. Turn the director selector switch and the illumination switch to "OFF".

  4. Turn the bridge transfer switch and the heater switch to "OFF".

5. Turn off the power to the torpedo director at fire control switchboard.

6. Cover the torpedo director with tarpaulin provided.

Figure 26-Front right view Torpedo Director Mk 27 Mod 5.
Figure 26-Front right view Torpedo Director Mk 27 Mod 5.
 
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