Some brief info on PRINZ EUGEN

[Byron Angel]

Some KM data re PRINZ EUGEN
The following is a fragment from an unidentified USNI article on Prinz Eugen passed onto me by a friend a few years ago. I forgot I had it and just tripped over it a few minutes ago while hunting something else –


During a refit after her February 1942 return to Germany, Prinz Eugen’s foretop FuMo 26 range finder was topped by an additional unit, above the 2 x 4 meter mattress and below the slightly smaller “Timor” frame, both bearing in the same direction, while the screen of the foretop platform carried passive “Sumatra” antennas, bearing in all four directions. Prinz Eugen was, moreover, unique in having a special height finder set with an aerial consisting of two rectangular frames that could be switched in elevation. The left one carried active dipoles, the right passive ‘butterfly’ dipoles with vertical polarization. This may have been an experimental set for air search or for AA fire control.

When she was taken over by the United States, Prinz Eugen had a FuMo 26 on the foretop, a FuMo 81 at the foremast truck, a FuMo 25 on a platform abaft the mainmast, and an (sic) FuMo 23 as the after rangefinder. Prinz Eugen also carried a sophisticated hydrophone system called the Gruppenhorchgerat (Ghg). This consisted of two groups of sixty receivers in Compartment X. Each group was connected to a highly trained operator. This system detected the approach of Hood and Prince of Wales at 32,000 meters.

FIRE CONTROL
In the main batteries the ship carried four 7-meter range finders, in the foretop, the after fire-control position, and in B and C turrets. There was also a 6-meter range finder in the forward fire-control position. At night, fire control was conducted by four night-target “columns” on each side of the forward command post on the bridge. These positions were equipped with specialized light-gathering optics.

Turrets and guns could be fired individually. The range finders were linked to forward and aft main- battery plotting rooms (or control centers). The C/38 K fire-control computers continuously received the range from the range finders and displayed it on graphic time charts. Range rate (the rate of change of range over time0 was calculated from the slope of a range-time graph and put into the computer. The computer then calculated the range and deflection and transmitted that information to the gun-control units. There were also inputs for wind speed and direction, own course and speed, and target course and speed. There were three command posts, and each turret had auxiliary gear to enable fire to be maintained in the event of a breakdown in the main plotting rooms or a rupture in the cable connectors.

The Prinz Eugen was equipped with two stabilizing units, Rw Hw-Geber C/38 tilt-correction devices. These supplied stabilized bearing and direction values to compensate for pitch, roll and changes of own course. This allowed the guns to maintain continuous aim and to engage two targets simultaneously.


Hope this is (a) correct; (b) useful.

Byron

[TTTT]

I posted this on a different post, but I take the liberty to post it here, too.

US evaluation of Prinz Eugen, comments on radars etc.

The cruiser Prinz Eugen was the largest and most modern German surface ship to survive WWII intact. Allocated to the United States, the ship briefly served as USS Prinz Eugen (IX-300), having some equipment stripped off for study and then being expended as an atomic bomb target.

Here are some comments from the americans on radar etc.

The FuMo 25 radar
This rectangular antenna was carried on the aft mast. It was just a general-purpose radar with a range of about 10NM.
FuMo25This system was already obsolete even when compared to WWII-era American radars, let alone the first postwar models, and little was done in the way of exploiting it’s technology.

The FuMo 26 radar
This was the most visible of Prinz Eugen‘s radars, being carried on the rangefinder atop the conning tower. It was a ship-to-ship gunnery radar. The basic model had a range of 13 NM.
The German sailors told the Americans that their ship’s FuMo 26 was an upgraded, even more advanced model with a short 4 microsecond pulse and a range of 21NM. This upgraded model had accuracy of ±55 yards and the Germans considered it sufficient for “blind” targeting of enemy cruisers or battleships. Perhaps due to it’s sophisticated nature, the US Navy personnel never quite mastered the FuMo 26 in the short time the cruiser was on the East Coast. It was decided to leave it aboard to witness the effects of a nuclear blast upon a high-end foreign radar.

The FuMo 27 radar
This radar was carried on the aft rangefinder. It’s only function was to measure the distance to a targeted ship.
This radar had constant technical problems when the cruiser was in American service. Little was done to study it.

The FuMo 81 Berlin-S radar
This small antenna was carried atop the main mast. It was a high-frequency radar used to localize targets detected by other radars. It was judged inferior to existing US Navy radars.

The FuMB 4 Sumatra ESM system
These small antennas on the conning tower intercepted enemy radar transmissions and warned the captain if Prinz Eugen was “being painted” (targeted by an enemy gunnery radar). The US Navy personnel considered it of average abilities.

Other equipment

The GHG sonar system
For certain, this was the greatest prize of all taken off the German cruiser. The GHG sonar was, by WWII standards, very advanced. It had a spaced array of multiple crystal hydrophones with electric signal delays. This radar could detect a ship out to 10NM in quiet conditions, and because of the signal delaying, it was possible to determine a contact’s bearing and course.

The americans were impressed with the accuracy and range of the main guns, and viewed the AA guns as comparable with their own.

https://wwiiafterwwii.wordpress.com/201 ... inz-eugen/

[Thorsten Wahl]

This upgraded model had accuracy of ±55 yards

reading accuracy was in 50 m steps that doesnt mean that accuracy was 50 m. As the signal was represented by a analogue zag with a distinct summit a experienced operator could refine that.

A Würzburg with the same transmitting tube but different ranging unit had improved accuracy up to 10 m independend of range.

The reference to absoelete equipment may be correct, as there were cheaper technical solutions available to improve performance of radar with magnetrons by sheer poweroutput.

The german approach was somewhat different. Magnetrons didnt produce uniform signals. The signals produced by the TS tubes were of extreme uniformity.
Such signals could be manipulated to extract the required information. Modern radars use Klystrons exactly for this reason.