The German TDC

[joegrundman]

Does anyone know what the capabilities of the historical Vorhaltrechner actually were?

[Letum]

Much as in game.
It was little more than an instant angle calculator that could update in real time.

[looney]

What do we know about the other countries TDC?

English, dutch, Russian, japanese etc etc??

[Hitman]

British report about the captured U-570 Fire control computer:

Torpedo Control


71. Torpedo fire is controlled from the conning tower or from the bridge; electric firing pistols are fitted in both these positions.
72. There are three sighting positions - the two periscopes and the night director fitted on the bridge. Each of these is fitted with an electrical relative bearing transmitter. The position in use is connected to a receiver in the calculating instrument by a selector switch on the control panel.
73. The night sight consists of a pair of very good pressure-tight binoculars on a revolving mounting. It is a line of sight transmitter only and has no means of calculating the director angle other than the calculating instrument. Torpedo control by night is the same as by day.

The Calculating Instrument

74. The calculating instrument is in the conning tower close to the attack periscope. It is considerably more elaborate than the British Submarine Torpedo Director and has a large number of dials but it does not give a clear picture of the relative position of own and enemy ships as does the British instrument.
75. The calculator performs the following functions:

A. Calculation of Director Angle

Settings

(i) Torpedo speed. Three positions 44, 40 or 30 knots set by hand.
(ii) Enemy speed. 0 to 40 knots set by hand.
(iii) Inclination. Set by hand in the first instance and then corrected automatically for change of bearing. This gear must be switched off when resetting inclination by hand.
76. The resultant director angle is shown on a dial on the face of the instrument.

B. Calculation of Gyro Angle

77. The instrument generates the gyro angle from the formula G.A. = Line of sight (relative bearing) + Director angle + Convergence. Settings (i) Line of sight. Received electrically from the sight in use. A hand follow-up applies it to the instrument. When the sight is not being kept continually trained on target a switch is made which burns a blue lamp in the calculator to indicate "Do not follow." (ii) Bow or stern tubes. Set by hand switch on the instrument and ensures gyro angle and convergence are applied in the right direction. (iii) Range. Set by hand. (iv) Rate of swing. Set by hand (degrees/second). The purpose of this setting is to apply a correction to the gyro to allow for swing when firing a salvo with the submarine under helm. Note. There is no indication that hydrophones or other detecting devices are used to give a "line of sight" for firing blind. 78. The gyro angle generated is shown on the face of the instrument and is transmitted to the receivers at the bow or stern tubes through a selector switch on the control panel.

C. Calculation of Spread Angle

79. Settings (i) Range. As above. (ii) Inclination. As above. (iii) Length of target. Set by hand. 80. The total angle of spread is shown on a dial on the face of the instrument and is transmitter to the receiver at the bow tubes.

The Control Panel


81. The control panel is in the control room, it forms a junction box for the torpedo control circuits and carried the following selector switches:
(i) Line of sight. Two periscopes or night sight.
(ii) Gyro angle. Bow or stern tubes.
(iii) Firing circuit I. Each tube separately or "salvoes."
(iv) Firing circuit II. Various combinations of 2-, 3-, and 4-tube salvoes.

Gyro and Spread Angle Receivers


82. The gyro and spread angle receivers at the bow tubes are mounted in a gear box with hand or automatic follow-up gear. Following the pointer in the gyro angle receiver operated a mechanical drive to the external angling gear on each tube. Any angle between 0° and 90° R. or L. can be set in 1° steps.
83. The spread angle receiver is fitted with a selector switch which can be set for three different "spread methods." Following the spread angle pointer applies a correction to the mean gyro angle transmitted to each tube.
84. The gyro angle receiver at the stern tube is fitted with a hand-operated follow-up, which works a mechanical drive to the external angling gear on the tube.

Firing Methods

85. Three methods of firing are used. Salvoes, multiple shots and single shots.
86. In salvo firing No. 1 selector switch is set to "salvoes" No. 2 to the particular combination of tubes to be fired. On pressing the firing pistol the first torpedo is fired and an automatic timing relay is energised which fires the remainder in succession with the minimum firing interval. This interval is stated to be 3 seconds, but it is known that later instructions have been issued that the firing interval is to be not less than 8 seconds.
87. In "multiple" shot firing torpedoes are fired singly on the same course at 8 seconds interval. The first shot is aimed ahead of the centre of the target a distance equal to two times enemy speed, in metres.
88. In single shot firing each torpedo is aimed and fired separately.

[Letum]

What do we know about the other countries TDC?

English, dutch, Russian, japanese etc etc??

The American TDC could track the target's predicted heading from the u-boat
without a visual contact. You put in all the data, set it off and then it constantly
updated the heading to target.
This had the advantage of telling you how good your solution was. i.e. if it
is a good solution then the predicted heading will match the visual one. However,
it was not much use for no-visual attacks as it multiplied any error in the initial
inputs by the time since the last visual check.

[looney]

As I'm playing SH4 now I have left map updates on.. Cause I want to make sure my solutions are correct.. How to double check the solution in an American TDC.. The german only solves the giro angle so you can set it b4. This can't be don in an american sub cause the tdc isn't linked directly to the scope.

[UnderseaLcpl]

What do we know about the other countries TDC?

English, dutch, Russian, japanese etc etc??


I recently learned that Poland's TDC required 20 Poles to operate. Still looking into to the reason.