U-boat targeting calculation

Discussions on all (non-biographical) aspects of the submarine forces of the Kriegsmarine.
ametzeaala
Member
Posts: 7
Joined: 05 Nov 2013 12:41

U-boat targeting calculation

Post by ametzeaala » 11 Nov 2013 15:30

Hello!I am new to the forum so hello everyone!
I am passioned by submarines and navy and i was always a fan of submarine simulation games:).
I was always wondering how they were estimated the ship position.
I know that to be able to hit a ship,they needed to be at a distance of 1km-500 m at a 90 degrees angle.They needed to calculate the distance,angle on bow and speed of the target.
Some people told me that they used stadimeter for range,some told me they used some sort of ring attached to the periscope to estimate the angle on bow and range,and i think they used a chronometer for the speed.But i really want to be sure.So if you guys can explain me how they did all this calculations i would be very happy.:D

P.S.:here is a photo of that "ring" i was told they used-http://www.subsim.com/radioroom/showthread.php?t=147667

SnakeDoc
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Posts: 20
Joined: 21 Oct 2013 11:29
Location: Warsaw, Poland

Re: U-boat targeting calculation

Post by SnakeDoc » 12 Nov 2013 10:42

Hi,

to be strict, to aim the torpedo, you only need enemy speed and enemy angle on bow (and torpedo speed, but it's not problem, of course). And to determine these, you may need to estimate distance.
The distance may be determined in many ways: by eye, by means of stadimeter or graticule in periscope, by radar or sonar. The ring you have linked is so called "Doppelbild-Entfernungs-und Zielkurswinkelschätzer"
(look here: http://uboat.net/forums/read.php?3,8788 ... #msg-87890).
Germans in their periscopes did not embed stadimeters - the fixed-eye-level periscope used on type VII and IX U-Boats, as well as air-periscope did not have such devices - they only used graticule. Americans used stadimeters, radar and sonar.
Generally, you could estimate enemy speed and angle on bow by eye - the accuracy depended on your experience. The advantage of this method was speed - you could have these value immediately.
If you want more accurate data, you have to plot - in regular periods of time you get bearings and distance (with any methods mentioned above) to the enemy and plot them (together with your own speed and course) on the map. After some observations, you can clearly see the course and speed of enemy. Of course, plotting takes some time, and this is main disadvantage.

--
Regards
Maciek

ametzeaala
Member
Posts: 7
Joined: 05 Nov 2013 12:41

Re: U-boat targeting calculation

Post by ametzeaala » 12 Nov 2013 16:53

Thank you very much for the reply:)

Simon Gunson
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Posts: 718
Joined: 23 Mar 2004 00:25
Location: Wellington, New Zealand

Re: U-boat targeting calculation

Post by Simon Gunson » 08 Mar 2014 14:05

There was a device which worked as a clockwork calculating computer whiconstantly updated firing solutions once the range and angle to target were imputted

The UZO (Underwasserzieloptik) on the bridge was mounted on a pedestal generally located forward. It was comprised two parts; a set of large, pressure resistant watertight heavy binoculars and a rotatable bracket set in a degree-marked ring.

This was linked to a mechanical analog attack computer (Vorhaltrechner, A Siemen's-built electromechanical deflection calculator) in the U-boat's conning tower which fed attack headings into the torpedo launch receiver (Torpedo Schuss- Empfanger "T-Schu").

These were located in both forward and after torpedo rooms. They received the fire control solution (gyro angle) and fed it into the guidance system of the tube-loaded torpedoes, via retractable "spindles" inserted through the torpedo propeller hubs.

In U-boats, the attack periscope and UZO were linked to the Vorhaltrechner, and when the target was properly aligned, the mechanical connections between the boat's gyro-compass and the attack periscope (or the UZO), provided the "attack computer" with data about the current course and speed of the U-boat and the bearing to the target. The target's range, speed, heading and rate of turn of the U-boat, had to be inserted for calculations to work. After the required data was inserted, a firing solution was achieved and the FAT torpedoes would be instructed before launch which way to turn and at what rate. Thus a U-boat could travel surfaced on a parallel course and still fire at a target beside the U-boat.

When the u-boat was submerged at periscope depth and thus much slower waiting in ambush for example, the Officer in charge would climb to the small cabin side the conning tower above the control room and moving aft would sit in a cupola ring which he could drive around the attack periscope shaft with foot pedals. Firing solutions were also indicated on a translucent under-lit plotting table in the control room assisting the navigator to monitor and plot the action.

From then on, any change in the course or speed of the U-boat, or in the target bearing received by the attack computer, a new solution was calculated automatically, and the gyro angle was passed automatically to the tube-loaded torpedoes.

The U.S. Navy used a Target Bearing Transmitter (TBT) mounted on the open bridge, which sent the same data to theTorpedo Data Computer (TDC) located in the Conning Tower. The solution was transmitted to the Gyro Angle Regulator ( one in each torpedo room) mounted between the torpedo tubes. Electrical inputs from the TDC were constantly transmitted to the regulator, and an operator matched the "bugs" on the mechanism's dials as the gyro angle is being fed to the torpedo's gyroscope via suitable linkage and spindles attached to the tubes.

Hope this helps?

ametzeaala
Member
Posts: 7
Joined: 05 Nov 2013 12:41

Re: U-boat targeting calculation

Post by ametzeaala » 01 Jun 2014 20:17

Thank you Simon Gunson and i am really sorry for this abnormaly late reply!Unfortunately i have had problems with my computer!Yes this really helps me thank you very much!

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