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BATTLESHIP BISMARCK ARTILLERY TESTING REPORT

(This document was translated from the German by Ulrich H. Rudofsky)

Updated 02 October 2020

Kiel, 31 May 1941.

Artillery Testing Command
for Ships [AVKS]
Report Number 700 Secret

Control Number 45

Secret

Final report

AVKS Report No. 700/41 secret

AVKS Tests aboard Battleship “Bismarck”

Distribution.

Office
No. copies
Control No.
High Command of the Kriegsmarine [OKM]
Inspection of Naval Artillery
Fleet Command
Commander of Cruisers
Command of Battleship “Tirpitz”
Testing Command for New Warship Construction [EKK]
Ship Artillery School
Artillery Testing Command – Land
Naval Anti-aircraft and Coastal Artillery School
Navy Shipyard, Kiel
Navy Shipyard, Wilhelmshaven 		20
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In house:
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TABLE OF CONTENTS.

I. Introductory remarks for the conduct of the tests.

II. Surface target artillery.

III. Flak – artillery.

IV. Rangefinder [Em] facility.

V. Concluding remarks.

I. INTRODUCTORY REMARKS FOR THE CONDUCT OF THE TESTS.

1. Tests in port.

The originally scheduled date for the AVKS time allotment for the battleship “Bismarck” was planned for the period from 3 February until 1 March 1941. This time frame could not be kept because the ship could not leave Hamburg until 6 March 1941 due to ice obstructions and closure of the Kaiser Wilhelm canal.

In order to take proper advantage of the enforced layover in Hamburg, the AVKS already boarded “Bismarck” on 29 January 1941.

In as far as the operational conditions and the circumstances allowed, tests were conducted during this time; in particular, investigations of the remote control for elevation of the heavy artillery (accuracy measurements, sluggishness [retardation, delay] and acceleration measurements of the hydraulics), the pre-ignition [fuse setting] mechanisms and Flak remote controls, the traversing directional devices of the Flak fire control stations, the drive controls of the rangefinder rotary domes, etc. Furthermore, the AVKS was substantially helpful to the ship’s command for training (switching exercises, rapid transport exercises).

It has to be pointed out that important segments of the artillery installation would not have been ready for the AVKS tests, if the prolonged delay in port had not come to the rescue (e.g., elevation remote controls of the heavy artillery and Flak remote controls had not yet been accepted; the radar [Em-II] instrument had not yet been installed as well as some other items).

2. Tests at sea.

It was feasible to begin the tests at sea on 19 March 1941. At the start of the tests, a duration until 11 April was anticipated. Due to a new order from the High Command of the Kriegsmarine [OKM], which was sent only to the ship’s command, the AVKS time, however, had to be cut short and to end on 2 April.

Under these complicating conditions, a considerable portion of the intended tests had to be abruptly dropped. More or less, only the conduct of those firing exercises remained intact that had immediate relevance for the training of the ship and the establishment of the physical readiness of the artillery installations. All tests that went beyond this, as those that primarily involved further technical development [fine tuning], such as shot-group [dispersion pattern] firing to determine the battery scatter as well as all measuring surveys of a technical nature, had to be regrettably stricken. The shot-group firing at anchor, to determine the battery scatter of the 38 cm battery have since then been obtained by a remedial make-up onboard “Tirpitz”.

For the conduct of the firing tests themselves, the following is noted:

II. SURFACE TARGET ARTILLERY [Seeziel-Artillerie].

A. 38 cm battery.

3. General aspects.

4. Sight system.

5. Main traversing machinery [mechanism].

6. Elevation machinery.

In order to alleviate the load stress on the gear drives by the hydraulics, a cataract [hydraulic brake, dashpot] was built into the elevation aligning hand-wheel that is supposed to prevent the abrupt closing of the control sliders. This design severely impedes the alignment operations. Performance of alignment exercises has demonstrated that the upper limit for alignment of roll amounts to roll angles of about +/- 3 to 4 degrees. At 4 degrees angle of roll the alignment errors on average are about +/- 6/16 degrees, with outriders of up to +/- 10/16 degrees. At +/- 6 degrees angle of roll a realigning adjustment is impossible. In view of the alignment actions it would, therefore, be quite desirable to have a cataract that operates more smoothly.

On the other hand, it appears that the cataract does not fulfill its function anyway, since during hand alignment even harder knocks occur in the hydraulics than [would take place], for example, during elevation alignment done by remote control. It cannot be determined at present if these harder demands on the hydraulics could lead to damaging the hydraulics. At the start of the tests erosion wear was found on the tooth flanks of the elevation alignment rack and the elevation alignment pinion, and this was [found to be] the case in several turrets. Although these signs of erosion wear were noticed only in the loading position, it is suspected that there could be some other causes involved. (see also item 9.)

7. Alignment for elevation and azimuth.

The limits decrease also with increasing caliber, since the ship’s motions during alignment for elevation and azimuth as well as the adjustment for the directional pointer, is dependent on the direct alignment procedure. [not sure of meaning here]. The maximal limit of the alignment [deviation?] of a 38 cm turret can be assumed to be about 4 degrees for the tilt angle for the elevation alignment device and about 3 degrees for the azimuth angle of the traversing mechanism. [not sure what that means].

It is not to be assumed that in the near future a noticeable progress can be expected by further improvement of the alignment systems per se.

This leads to the notion that even in the turret guns of the surface target artillery, the azimuth as well as the elevation alignment must be tested [calibrated]. According to experience with the Flak artillery, the expectation is that even here a simplified directional pointer is more suitable then the commonly used accelerated alignment. First of all, this applies to the constant compensating turns during yawing, i.e., while hobby-horsing [pitching]. Undoubtedly, the more compliant directional alignment will reduce the demands on the hydraulics and ship’s electrical systems.

The on-board installed controls for azimuth and elevation could be improved with more simplified devices, e.g., with reversing differentials [?] for final alignment. A test is proposed to do just that.

8. Auxiliary elevation mechanism.

The required testing of the auxiliary elevation mechanism that was mandated by the testing procedure directive for the firing of actual shots could no longer be accomplished because of the curtailment of the testing period.

9. Characteristics of the hydraulic drive.

The calibration of the barrel elevation controls was difficult because the controls were very susceptible to oscillations. In order to determine the causes, detailed examinations of the hydraulic drive of the turrets were undertaken. The presumption was that the reason for the oscillation was the mechanical play [looseness] in the elevation drive, and that could be seen with bare eyes. In the investigations, both the static and the dynamic looseness were found. The following results were obtained:

10. Performance rating of the electro-hydraulic remote control mechanisms.

During the layover in the harbor of Hamburg the opportunity arose to conduct a thorough investigation of the barrel elevation remote control. The investigations concerned themselves mainly with the determination of the relation [connection] between the hydraulic and electric systems and the elucidation of basic questions related to future improvements. The experimental results will be presented in a separate special report.

The following can be stated regarding the remote control:

11. Vo muzzle velocity settings for elevation by remote control.

The requirement for taking into account the Vo variation of the individual turrets during alignment of elevation by remote control has been repeatedly pointed out and it also applies to the 38 cm turrets. To accomplish this requirement, there are basically two alternatives:

12. Azimuth – Velocity-at-target [impact velocity] mechanism.

13. General items regarding the ammunition transport equipment.

The ammunition transport equipment could be tested only during rapid transport exercises in port and during firing in calm waters. A test while the ship was rolling was not possible [due to weather conditions]. A judgment as to the effectiveness of the ammunition transport equipment during swells [motion of the seas] cannot be submitted.

14. Main elevators.

The transport performance of the main elevators was determined with a stopwatch. It consisted of about 23 to 25 shots/minute [in total for all 4 turrets]. In addition to several failures of minor consequence, there occurred two elevator failures of fundamental relevance, and these require an in-depth retesting. The parking of the cartridge elevator in the cartridge loading station proceeds one-sided, i.e., the elevator has a support with a guide pin only on one side, while the other side is suspended freely in the elevator shaft. Disregarding the fact that this type of uneven load places stress conditions on the loaded elevator that are problems in themselves, but during operational failures, the one-sided support could lead, for example, due to particular external influences (trapping or seizure of a cartridge lid), to the inability of the elevator to park at the cartridge loading station and completely pass by and seat itself at the shell elevator at the shell loading station. This failure did occur aboard “Bismarck” and this led on each occasion to a complete and prolonged shut-down of the elevator. It is proposed that the construction design be changed in such a manner that the elevator is caught on both sides at the cartridge loading station. First of all, this would provide a better momentum distribution and it would especially achieve greater assurance for the flawless parking of the elevator.

15. By-pass of the hoist and transport winches.

The by-pass position of the hoist and transport winches of the shell chamber leads to serious failures because they did not open properly when the overhead trolley passed through, resulting in the crash of the trolley into the partially lifted stop [bed?]. The cause was the large amount of play in the by-pass drive.
Furthermore, the investigations revealed that the entire set of safety bolts in the adjustment connector [clutch?] had their nuts missing. [The play in the drive] led to the loosening of the nuts and disconnection of the drive parts so that the by-passes no longer worked effectively. Since the entire transport of ammunition depends on the flawless functioning of the hoist and transport winches, a great deal of emphasis must be placed on sturdy construction and reliable installation.
Details are separately pursued.

16. Reloader in the shell chambers [Granatkammern].

The redesign of the reloading [transfer] head in the shell chambers of “Bismarck” has prevented damage to the lifter [pestle, ram?] screw on the head of the shell during transfer. But if the “Ringwagen” [ring cart, carrousel, carriage?] has already been pivoted, before the reloader is backed away (which is certainly an operator’s error), then the lifting screw can still be damaged by the reloader [transfer] head. The guide on the head is attached in a way that, in its final position, is lateral to the lifting screw (i.e., at the carrousel). In order to prevent damage to the lifting screw, even in this case, the manufacturer ought to ascertain if there is a simple solution to correct this potential problem.

It seems appropriate to provide the reload transfer device with an additional second, reverse head for restacking projectiles in the rear storage area.

17. Turntables in the lateral cartridge chambers [Kartuschkammern]. Turret D.

For the transport of cartridges in the cartridge chambers, a turntable is provided for the upper chambers in turret D. The table is very space-robbing. The table is a real impediment for cartridge transport from the lower to the upper chamber. In order to improve the poor spatial arrangements that occur in the fully loaded cartridge chamber, the command [AVKS] has extended the planned cartridge pass-through table used for passing cartridges from the upper cartridge chamber to the carrousel cart far enough so that cartridges can be placed on it while still in the cartridge chamber. This measure has proven itself to be superior. The turntable is therefore superfluous and can be dismantled.

18. Capstan [windlass] machinery in the shell chambers [Geschoßkammern].

A windlass is available for transporting shells from the anterior shell stores of the chambers in turrets A and B. This arrangement is adequate. No operational difficulties arose.

19. Reloader [transfer loader].

The diameter of the transfer loader head is too small. During the pushing-out of cartridges from the elevator into the loading locker [cabinet] the lid of the main cartridges was dented because the contact surface of the transfer head is so small that the lid was dislodged. In order to avoid such problems, it is urgently recommended that the diameter of the transfer head be enlarged.

20. Blocking between the rammer and the loading conveyor.

At present, there is no blocking between the guide [rammer] and the loading conveyor [bail, crane]. Therefore, it is possible that an operator error could damage the guide with the loading conveyor. Although this blocking is desirable in the 38 cm turret, it is not considered absolutely vital. A blocking device seems only justified when it is necessary for operational safety and can be built without a major effort.

21. Shell casing ejection.

The drum ejector, with its shell casing ejector lid, which has been built into turret A, appears to be a considerable improvement over the customary ones in the other three heavy artillery turrets. Testing in heavy seas, however, was not possible. The present design, however, does not prevent the influx of water at the moment of casing ejection, because the drum has two diametrically-positioned locations on the drum that have cutouts for weight saving reasons. In order to achieve good water-tightness during casing ejection, it is proposed that the drum be provided with a housing that has a hinged cover on its front side for the insertion of the spent shell casings. The hinged covers should be attached in such a manner so that they can only be opened in the direction of the casing ejector and closed against seawater spray.

22. Shell casing receiving [catcher]device [Hülsenfangvorrichtung].

The present construction of the shell casing receptacle is useless. The shell casing net is too small. During case ejection the casings often pop up so that they obstruct the catching device. The attachment was furthermore made in such a manner that the device did not freely transport the casings to the removal chute located at the barbette armor. Also, it happened repeatedly that this device, particularly at turret B, was bent by wind and water forces; and therefore, it had to be removed. A considerably stronger and more functional fabrication is necessary.

23. Auxiliary [accessory] elevators.

24. Smoke evacuation.

The smoke evacuation in the turrets is still entirely unsatisfactory. This evaluation is dependent on constantly different and changing environmental factors occurring in each individual turret, since the smoke conditions are heavily influenced by external factors (the ship’s superstructures, turret orientation, wind direction, etc.).
Based on the few and comparatively brief firing exercises with full caliber ammunition during the brief AVKS testing period, a final judgment and more detailed proposals for improvement cannot yet be made. The ship commands must report further observations.
N.E. [?] must attack the problem of designing and testing a fume-evacuating [blow-out] system in the barrel in order to obtain a radical solution to this problem.
As far as could be determined at present, a special fresh air supply duct for the machinery platform is considered unnecessary.

25. Smoke baffle lids.

The smoke baffles made by “Isola”, which were taken aboard for testing, were not proven useful. The testing has already been reported in AVKS Report No. 511 secret, of 16 April 1941.

26. Water-tightness of turrets.

At present, the barrel embrasure sealing gaskets are inadequate. It was observed that during spraying with fire-extinguishing water, water does enter the turret. This point was already followed up in OKM Report A Wa A Ib 4452 secret/41. In the case of the cartridge shell ejector openings, see cipher 21.
The water-tightness of the bearing telescopes and their sealing gaskets against the turret armor plating was presently observed to be unsatisfactory. Already at moderate seas, water seeps through the gaskets of the bearing telescopes into the turrets as well as into the bearing telescopes themselves, fogging them; this is particularly noticeable in the forward turrets.
Reference in this matter is made to the relevant reports from ships now deployed in the Atlantic. Remedial action is urgently required.
A final evaluation of the barbette gaskets and the barrel gaskets cannot be made, since the there was insufficient wave action during the testing period.

27. Warning equipment.

28. Turret operations telecommunications loudspeaker system.

The noise levels in the 38 cm turret are considerably higher than in the 28 cm and 20.3 cm turrets. That pertains particularly to the machinery platform. Despite the fact that there are 3 loudspeakers with an output of 10 W each, this speaker volume does not penetrate to all locations of the machinery platform. Experiments with the a 4th loudspeaker, selectively positioned in various locations, showed that a substantial improvement could not be achieved, although echo effects were generated which distorted speech. In order to achieve an improvement, it is suggested that the now present directional loudspeakers in place, be replaced by mushroom-type omni-directional loudspeakers. An obviously better sound distribution will thereby be achieved that will more likely require speakers of lesser output.

29. Manual crank operation of the breech mechanism.

The manual crank handle of the breech mechanism should snap out of the way automatically as soon as the breech is closed so that it will not get hung up on the gun mount during elevation adjustment of the barrel. At present, the folding-away of the handle does not occur with absolute reliability. It repeatedly occurred that the cranking handle did not fold in the final end-position, and then broke off during elevation alignment. The cause apparently lies in the fact that the locking pin does not freely engage in the seating. A more functional design is necessary.

30. Azimuth drive of the bearing telescope.

The hand-wheels of the azimuth alignment of the bearing telescopes are at present located on the ceiling of the turrets. Since the bearing telescopes are often very sluggish in their lateral adjustment and can be moved laterally only by using a hand-wheel, it is proposed that a hand-wheel of similar design be attached right next to the bearing telescope, just as is the case with the artillery observation scope in the fire control stations.

31. Turret position indicator.

The degree increments are missing on the mechanical turret position indicators at the gun platform. Therefore, it cannot be determined in which lateral direction a particular turret is facing.

The attachment of electric turret position indicators, at present, is not very useful and logical. In order for the turret personnel to get an instant picture of its own turret position and that of the turret group itself, without rethinking, the turret position receivers are to be modified by turning them 90 degrees and adding an arrow, or some sort of mark, to the housing that indicates the ship’s own axial position. The two receivers must then be logically mounted on the housing and calibrated to be truly analogous to the position of the turrets on the ship, i.e., to be observable side-by-side and fore and aft with the ship’s longitudinal axis, and not as now, athwartships.

32. Availability of connections for dynamic tachometers and potentiometers.

As had already been requested in AVKS report no. 1455 T I of 1 August 1939, connections (flange couplings, etc.) for dynamic tachometers and potentiometers were to be provided in all new turret constructions [designs]. The availability of such connectors for testing instruments has proved to be useful in the systematic investigations of the traversing machinery and elevation adjustment machinery. The measuring instruments can then be connected at the testing locations as needed, without a great deal of preparation. This considerably speeds up turret inspections.

Since these installations were not available in the 38 cm turrets, and since the testing equipment that was originally built for AVKS tests by the ordnance technical group at the Wilhelmhaven proving grounds had been destroyed in an air raid, adequate measuring equipment could not be obtained due to time constraints.

The proposal is renewed that, in the future, the installation of receptacles for testing equipment within the turrets be accomplished during construction and that the required testing equipment is made ready in sufficient quantity.

33. Heating in the turrets.

The necessity concerning heating in the turrets has been previously reported in AVKS report no. 317 secret TI of 8 March 1941. In regard to the dimensional volume of the heating capacity, it is concluded that the capacity of 50 kw in turret A is quite adequate, while the thermal capacity of only 13.5 kw in turret C is a considerable improvement, although it is not considered sufficient for all conditions.
Therefore, it is requested that all heavy turrets will be equipped with a heating capacity that is of the size of the one in turret A.

34. Ammunition transfer winches.

During the transfer of ammunition difficulties arose, since the Demag winches are installed separated from the elevator shafts. The signaling device for controlling the winches is inadequate. Insofar as the winches cannot be installed in the immediate proximity of the elevator shafts, it is in the interest of flawless operations to equip the winches with a remote handling [operating] control. Reference is made to Kriegsmarine Shipyard [Kriegsmarinewerft] Wilhelmshaven report no. secret 638 of 5 April 1941.

A simple proposal is to install a push-button switch that is attached to the Demag winch by a flexible electrical cable, which the operator, located near the elevator shaft, can hang around his neck.

35. Ammunition failures.

B. 15 cm battery.

36. General aspects.

37. Sight equipment.

38. Alignment indicator for the manual operation of traversing mechanism.

The present design of the alignment indicator of the manual traverse mechanism, with which manual operation of the manual traverse mechanism is displayed and in which direction it is to be traversed [rotated], appears to be quite inadequate. The drive adjustment for the alignment mechanism is done with a hand-wheel located at the left, i.e., right aiming position, and its turns are transmitted to the alignment indicator via flexible shafts. The repeated severe kinking of these shafts led to jamming of the transfer mechanism and, therefore, to the failure of the alignment indicator.

It is proposed to replace the alignment indicator with the installation of a battery-free telephone. In order to do this, all that is needed for the lateral adjustment crew is to attach a microphone to the sight. Furthermore, a “spy” [repeater] speaker needs to be placed at the machinery platform so that the crew of the manual traverse mechanism can overhear the orders that are given.

39. Elevation – velocity-at-target [Vz] [impact velocity] mechanism.

40. Turret operations loudspeaker system.

The amplifier boxes on the gun platform for the turret operations loudspeaker system in the short turrets (II and III turret) are attached to the turret ceiling between the barrels. This mounting method is in dire need of change. During firing of the heavy Flak guns at low barrel elevation the amplifier tubes in the box blew up. The mounting must either be much better cushioned or the box must be mounted in a more protected location in the turret.

41. Ready-report lighted display panel.

The ready-report lighted display panels for the Chief Gunner are located at the left corner of the back-wall of the turret. In order to be able to observe them, the Chief Gunner must turn around. It is more functional, if the panel were mounted to the left of the firing switch box or obliquely on the turret ceiling immediately in front of the Chief Gunner.

42. Electrical turret position indicator.

Even the electrical turret position indicator is mounted disadvantageously for the gunnery chief. It is located on the turret’s left side at the level of the left lock [closure, breech]. After the mounting of the rangefinder in the middle turrets, it will no longer be seen from the gunnery chief’s position. A transposition to the most advantageous proximity of the gunnery chief’s position is requested.
The requirement for receivers is, in a sense, the same as is listed in cipher 31.

43. Main elevators.

44. Ammunitions transport installation outside the turret.

45. Shell ejection.

The design of the shell ejector on the turret’s floor appears awkward. In order to prevent surging seawater entering the turret from below, more functional shell ejection shoots should be attached to the backside of the turret.

46. Fume exhaust.

The evacuation of fumes is not sufficient. During extended periods of firing it is only possible to operate the turret by opening the turret portholes [for ventilation], and especially from the residual after-burn of flare ammunition that generates a large amount of fume accumulation on the gun platform.

47. Heating in the turrets.

Even for the 15 cm turrets, heating is absolutely necessary. See AVKS report no. 317 secret of 8 March 1941.

48. Warning systems.

The proposed warning system planned for turrets I and III for preventing firing “against each other” - one half year after commissioning – is still not operationally ready. The warning devices are still missing. In addition, a few installation jobs of cable re-routings, i.e., the switchboard system, had not yet been accomplished by the shipyard. Since the warning system for prevention of “self inflicted attack” by the secondary artillery is of particular importance, such a work delay is intolerable for any reason whatsoever.

49. Access to connections for testing equipment.

Even in the 15 cm turrets it is desirable to have built-in devices installed during construction for the necessary measuring instruments used in conducting measurement tests of the traversing and elevation machinery. Compare with cipher 32 in regard to the 38 cm turrets.

C. Surface target fire control facility.

50. Layout and construction of the artillery command posts [Artillerieleitstände].

51. Arrangement of the operations switchboard and computer stations.

The room size in the artillery computer stations [Rechenstellen] is quite adequate. Operational conflicts do not even arise when the computer station is fully staffed. At any time, the command transmitter officer [BÜ-Offizier] can obtain a sufficient overview over the activity of the individual crew members.

The artillery switchboard stations [Schaltstellen] are also provided with ample space. The switching panels’ design are clearly arranged. Therefore, the engineering personal has the opportunity to rapidly accomplish the ordered switching, and to obtain a clear overview of their present switch settings.

Artillerie Rechenstelle
Artillery computer station (Artillerie Rechenstelle).

52. Artillery gunnery data computer [Schußwertrechner].

Nothing substantially noteworthy to report.
In the interest of design simplification of individual computer components, it must be reiterated that it has been proven once again that they are superfluous aboard the battleship “Bismarck”. This concerns, in particular, the entire equipment arrangement for setting command transmission switches and the equipment for manually setting sight angles at the gunnery data computer itself.

It seems important that in the future the opponent’s data, which are displayed on the photoelectric board [screen], are instantly transmitted from the gunnery computer to the photoelectric board. It has been demonstrated again that the settings on the gunnery computer display of the opponent indicator are very unsatisfactory. This produces an awkward effect on the firing evaluation.

Schußwertrechner
Gunnery data computer (Schußwertrechner).

53. Firing signal indicator [Feuersignalgeber].

54. The star shell guide unit [Lg-Leitgerät].

55. Control circuits of the surface target fire control center.

56. Average settings for the surface target fire control center.

In comparison with the original design of the average settings aboard the battleships “Scharnhorst” and “Gneisenau”, the switch settings on “Bismarck” have been designed so that in addition to the overall average settings, a partitioned average setting can be made for the stations, i.e., the guns, for the heavy artillery as well as for the secondary artillery.

No difficulties related to switching occurred during the use of average settings. It can be accomplished quite rapidly.

57. Current-gate controls [Stromtorsteuerung].

D. Telephone facilities of the surface target artillery.

58. Speaking buttons on the head-set telephone equipment.

The presently available telephone equipment has certain problems in that the wrong operation of the speaking lever can considerably disrupt fire control by producing additional noise interference. Very often, the telephone gear that is connected, but not in use, has the microphone lever in a constantly open position because of how it was hung on the wall. Since the microphone lever of the present design does not always prevent this, it is proposed that the microphone lever be replaced by a push-button. The attachment of the push-button should be made in such a way as to make its unintentional activation impossible.

59. Radar [Em-II] telephone.

The “Em-II-telephone”, with its special rerouting work and telephone outlets, is superfluous. At all locations where telephone outlets for this telephone have been placed, there are connections for the “Em-telephone”. The demands of the Em-II-telephone can certainly be assumed by the regular rangefinder [Em] telephone.

60. Telephone units without batteries.

The battery-less telephone units that proved themselves as a last resort communication already aboard “Gneisenau” have been permanently installed on “Bismarck” as single wall-mounted units. The units have proved themselves because of their low functional delay and their simple operation. A further development of these telecommunication units for future new constructions is recommended.

61. Switchboard rerouting of the gunnery telephone system.

The simultaneous switching of the gunnery telephone facility has been changed according to a proposal by the AVKS (AVKS final report battleship “Gneisenau”) so that the switching of the gunnery telephone no longer depends on the fire signal axis (Fs-axis), but rather the target indicator axis (heavy artillery, i.e., secondary artillery). The change is still missing on the labels on the switch-boxes regarding the co-activated settings.

E. Searchlight system.

62. Splinter protection cowls for searchlights.

The present splinter cowls on searchlights 2 and 3 do not have their own power-assisted aids for opening and closing. The movement of the splinter cowls is presently very cumbersome and requires a great deal of time. It is proposed that fleet command take the position that further observations be made on the necessity of a power-assisted operating device.

63. Average switch settings for the searchlight facility.

The fire control settings related to the searchlight average settings are partitioned in such a manner that the primary guidance values transmitted to the searchlight director device [Scheinwerferrichtgerät] are separated from the primary data provided by the aiming device of the searchlight’s own [local] alignment mechanism. The transmission switch-over of the guidance values to the searchlight director device is made separately by verification conducted via the searchlight buttons in the remote control box. Since the searchlight and the searchlight director device are a single unit, it is deemed more logical and simpler to combine the entire searchlight installation in such a manner that the average settings of the unit can be conducted with a common button, i.e., the present searchlight button that is presently on the remote control box.

F. Master [mother] gunnery aiming system [Muttererrichtanlage].

64. Layout of the master aiming facility.

The master aiming facility is arranged functionally. The available space is quite ample.
The subdivision of the rooms into one component room and one special switchboard room is convenient. The overview of the facility is thereby considerably improved and the maintenance is simplified.

G. Gyroscope rotation electric power supply.

65. The output of the gyroscopic power supply is, as is the present case aboard “Prinz Eugen”, quite sufficient. The available power reserves, as well as those of the forward and aft gyroscopic power supplies, are more than 100% [of the required power].
The interconnections of the facility within the ship are logical.

H. Vo [muzzle velocity] measuring system.

66. Cathode-ray tube oscillograph.

Since the Vo measuring system had only been partially completed, no final judgment can be rendered.
As far as the brief testing period allows, it can be said that the quadruple cathode graph recorder, which is the first of its kind ever to be installed, proved effective from a purely technical and operational perspective. A deficiency has surfaced anew that the quadruple cathode graph instrument, just as had been in use in the former single cathode tube scopes aboard the battleship “Gneisenau”, has no selectively adjustable locking device for the reversible moving part that allows several rapid salvoes to be photographed on single film [plate].

The system could only be tested during the firing of the secondary artillery. The measurement results obtained are attached in the special report of the AVKS – caliber firing “Bismarck”.

67. Connection for the Vo measuring system to the central firing device.

The connection of the Vo measuring system to the central firing device was originally designed so that the actuating impulse for the deployment of the cathode graph scope and for the initiation of the timing device in the turret would be connected by “S clamps”. Consequently, the entire additional electrical load of the Vo measuring system (14 relays, approx. 6 amps) had to be absorbed by the central firing device. Since the central firing device, however, is only fused for 2 amps, the fuses burned out when the initial operating sequence of the Vo measuring system was begun during the firing start-up. This led to serious disruptions during firing. In order to continue Vo measuring, the connection with the central firing device was done via attachments on the “D clamps”, i.e., in back of the firing relays. Since the turret’s electric firing circuit is considerably more heavily fused than the central firing circuit, no more failures occurred due to the connection of the Vo measuring system.

68. Drilling access ports into the barrels [for data collection probes].

Now, since the cathode graph scope has become a permanently installed onboard system, it is incomprehensible why, at the same time, the barrels were not drilled to accept the measuring probes.

If there is any hesitation about permitting the drilling of the barrels, then the cathode graph scopes, which have now been even provided with their own rooms, are simply carried aboard ship as dead ballast.

Aboard “Bismarck”, only the 15 cm barrels had been drilled for the planned shot group [strike picture] firing; while the 38 cm barrels had not been drilled at all. Presently, the same applies to “Tirpitz”, so that, unfortunately, no shot group [strike pictures] of the heavy artillery could be made by the AVKS, despite both completely installed cathode graph systems, and thus, no Vo, nor sequential total measurements, could be carried out at all.

III. FLAK ARTILLERY.

A. Flak deployment.

69. Configuration of the Flak battle stations [Flakeinsatzstände].

70. Layout of the target designation device [Zag = Zielanweisegerät].

Equipping the entire Flak deployment with only two Zag units is inadequate. During attacks from various directions a rapid deployment is only possible if there is a Zag for each heavy Flak group. A selective changeover of the Zag to individual stations using the telecommunication box of the main Flak deployment station is not feasible during radial-concentric attacks and rapidly appearing targets, especially because the switch box is only present on one side.

For the finalized Zag equipment configuration, four Zags are to be requisitioned. Each Flak group must be permanently assigned one Zag.

It is proposed that 2 Zags be installed at the main Flak battle station [in the foretop gallery] and 2 Zags at the aft reserve Flak battle station. The normal settings for the Zag: forward Zag for the forward group, aft Zag for the aft group. Since the Zag alignment number is connected via the command telephone of a particular group to the main Flak command post, there is no difficulty in issuing orders and target designation for the aft Zag.

Advantages of this arrangement:

71. Construction of the Zag.

The construction of the Zag has already been dealt with in detail in the final report of the cruiser “Prinz Eugen”. Overall, the Zag has also been proven a useful equipment aboard “Bismarck”. The following deficiencies are again pointed out:

72. Bearing [azimuth] discs [compass] instrument with auxiliary sight.

The azimuth discs with auxiliary sights that are installed in the main Flak command station have proven themselves as very useful target designation instruments in the hands of the Flak commander. They are simple in construction and operation. It is proposed that each reserve Flak deployment station be equipped with 2 such bearing discs.

B. Flak fire control facility [Flakfeuerleitanlage].

73. Layout of the Flak command stations [Flakleitstände].

The question arises as to whether the two Flak command stations put onboard would have been better positioned at the starboard and port sides of the [fore]mast or amidships aft. This cannot be solved decisively and has become outdated anyway. The advantages and disadvantages of both arrangements in regard to the sweep angle and susceptibility to hits are both important considerations.

74. Construction of the Flak command stations.

As an addendum to the final report of the Cruiser “Prinz Eugen”, it must be added that the basic remodeling proposals concerning the construction of the spherical Flak command stations, type SL 8, have proven effective anew aboard the battleship “Bismarck”; the local separation of the rotary ring compartment and the mechanical operations compartment of the Flak command stations A and B are not efficient. In case of failures, the mechanical personnel are required to climb out of their normal battle stations (rotary compartment) and enter the operations compartment by a detour in order to get at the remote control equipment of the operations compartment. In order to perform maintenance and repairs, a direct entrance way from the rotary compartment to the mechanical operations compartment is required.

75. Operational reliability of the Flak command stations.

The operational reliability of the remote-controlled Flak command stations in contrast to the directly stabilized Flak command stations has undoubtedly become better. However, during the brief time of the AVKS tests at sea, failures occurred repeatedly, that resulted, in part, in total shut-down of the Flak command stations. However, this concerns failures that in principle have nothing to do with stabilization.

The causes that led to major failures can be found below:

76. Stabilization of the Flak command stations.

77. Switchboard of the tilt and edge angle remote controls.

The direct current feed for the Flak command stations aboard the battleship “Bismarck”, in contrast to the cruiser “Prinz Eugen”, no longer comes from the switchboards of the gyro current control room, but directly from the ship’s circuit. The automatic switchover is located in the rotary compartment.

The feed for the remote controls and the gyro is dependent on the setting of the operating switch in the gyro current room. At the “start-up” and “operation” setting, the gyro, as well as the main switch box for the rotary current bus bar, from where the feed for the remote controls and the support motor controls are tapped, are operated on a three phase current. The former setting “reverse operation” – which involved a breaking of the gyro, is no longer required – the harbor operation setting is now used. At this setting, the gyros are no longer powered; and thus the bus board in the main switchbox is only connected to two phase outputs; since the alignment value remote control operates on two phase. However, three phases are required for the operations of the tilt and edge angle remote controls and the support motor controls.

Hence, the contingency does not exist that would allow operating the remote controls without also operating the gyros. However, this contingency must be made available. During shipyard completion, various facilities must often be made operationally ready at different times, and it is necessary to test completed facilities without interfering with work on other facilities.

The possibility of separating the gyro and remote controls is imperative for fine tuning the remote controls for accurate symmetry; and this can only be done when certain components are ‘lashed down’, i.e., with stopped gyros.

An asymmetric calibration of the remote controls creates a constant error. It occurs because the asymmetry’s specific fault current voltage is counterbalanced. During an interruption of the fault current (e.g., burn-out of the fuse in the bridging circuit), the remote control becomes single-sided. Therefore, each time the fault current was lacking, the instrument of Station A aboard the battleship “Bismarck” returned to the tilt angle final [stop] position. A correct recalibration of the remote control was not possible due to the impossibility of activating the remote control while the gyros were immobile.

Therefore, it must be requested that the rotary current bus board of the main switchbox be provided with three-phase current in order to facilitate the separation of the gyro and remote control units.

Since the gyros used in the ADE [?] component are displacement current flow devices, a step-up of the gyros with a step-up transformer is no longer required. Therefore, it becomes unnecessary to activate the operation switch from the rotary current location. It is proposed that in future new constructions, the operation switch be relocated from the gyro rotary current compartment to the rotary ring compartment, and to incorporate it in parallel into the feed switches present in the main switch box. The advantage of this layout is that all switching procedures are concentrated in the hands of the command post mechanic, thus, providing a more rapid operational readiness of the post.

A schematic outline of the proposed switching change is proposed separately.

78. Harbor [shore] power supply switchboard with remote control.

As was first noted onboard, there exists a difference between the harbor operation switchboard of the Flak command stations of the cruiser “Prinz Eugen” and the battleship “Bismarck”. Now the Flak command stations can go into action in port when the gyros are shut-down and while the alignment remote control is still functioning. It is now possible to align the guns with the alignment data unit while the gyros are down since the port switchboard can be directly linked to the Flak command station and no longer needs a target alignment that involves the gyro.

79. Reciprocal interference between Rw [Richtwinkel] alignment angle and Sv [Seitenvorhalt] lateral lead remote controls.

In order to determine quantitatively the reciprocal interference of the Rw and Sv remote controls, the investigations, initiated aboard the cruiser “Prinz Eugen” and continued aboard the battleship “Bismarck”, required some testing equipment that had to be installed to obtain the desired results.

The testing results again indicated that the interference on the Rw remote control system by the Sv remote control is considerable. The lateral deviations of the range finder platform from the target position were derived from photographs of practice firing, depending on the given velocity with which the Sv value is changed, in amounts to +/- 1 degree. Since the rangefinder has at total field of vision of only 1.5 degrees, when the rangefinder has been set at 40x magnification, the target is completely pushed out of the rangefinder’s field of vision by the oscillations of the two remote controls. The deviations occur at very sporadic intervals making a lateral realignment impossible and the rangefinder is, therefore, considerably impaired in its effectiveness.

A separate report will deal in detail with the testing results and proposals for changes.

80. Azimuth alignment devices of the Flak command posts.

Of the present four aiming possibilities:

... the path guidance is recommended for use, when possible, because of its well-known operational advantages.

The speed guidance control, whose two speed levels are accessed via an intermediate gear shaft, at a ratio of 1:4, is burdened with considerable operational difficulties. The rapid stop of the high speed operating mode, from maximum to zero, requires 7 full manual wheel cranks and 28 in the normal gear mode. Since the transition from “change target” to “pursue target” most often involves an abrupt change of speed (for target change high, for target pursuit lower speed), the reverse turns of the hand-wheel always consumes considerable time and also causes great difficulties for target acquisition.

The same difficulties arise during the transition from speed alignment to path alignment. In this procedure, the speed control must first be turned down to zero, otherwise the station’s lateral bearing is always off at one side.

The difficulties are even more pronounced since the speed control drive (Heinau-drives) has no tactile zero position. There is small, barely visible pointer attached to the control steering column. In order to recognize the zero setting, the lateral aligning man has to turn away from the optics and interrupt the target observation. This can lead to the loss of the target due to the alignment telescopes’ poor field of vision. The path alignment in the present configuration, however, does not permit achieving the necessary alignment speed for target acquisition. This has already been described in the AVKS final report of cruiser “Prinz Eugen”.

The further follow-up and appropriate modifications according to the final report of “Prinz Eugen” are encouraged. This involves the addition to the present path alignment control of two speed levels of approximate ratios of 1:4 and 1:5. The shifting for the choice of the two speed levels is activated most effectively by a foot pedal and in such a manner that the high gear, i.e., the high gear ratio, is activated by depression. When the foot pedal is released, the normal gear setting will be automatically activated by the force of a spring.

The path speed gear shaft can then be deleted, whereby the source of the error is also deleted.

81. Periscopic-leveling telescope C/9.

The inaccessibility of the periscopic-leveling telescope C/9 in the Flak command posts has already been reported in the final report “Prinz Eugen”. The present auxiliary sights have proven themselves to be sufficient for the target designation by the Flak commander.

82. Design of the Flak computer and switching stations.

The space of the Flak computer stations [Flak-Rechenstellen] is quite sufficient.
Since there are only four Flak command stations and since the calculators [Regs = Rechengerät] are permanently assigned to the Flak command stations, final equipping with 4 Regs (2 Regs for each computer station) is considered sufficient. The preliminary equipment of only 2 Regs, one for the forward and one for the aft computer stations appears to be effective.

The layout of the switching cabinets in the Flak switching stations [Flak-Schalstellen] is concise and the operation is greatly facilitated.

83. Computer/calculator Reg C/VI.

Nothing new in regard to Reg C/VI.
During the performance of the tests on the Flak elevation remote control, a second 10 degree elevation value differential pick-up [?] was found (gyro system) that was nowhere described in the available switchboard settings. It is mechanically and electrically connected to the remote control tack of the 10 degree Siemens differential pick-up system that is installed in the Reg. According to the gyro instruments [Kreiselgeräte] firm’s representative, the system is provided with enough adaptability to be updated, for example, when the Flak elevation remote controls, which are now Siemens controls, are later replaced by controls from the Firma Kreiselgeräte. Since it is assumed that the Siemens controls will remain onboard because their entire equipment has been properly installed, it is proposed to remove the superfluous and unnecessary displays [Geber = pick-ups?].

84. Steam influx into the forward regulator machinery compartment.

In order to prevent steam influx, none of the steam pipelines may be routed through the weapons operation compartments. However, aboard “Bismarck”, there are steam pipelines routed right through the anteroom of the forward regulator machinery compartment in which the circulating cooling system for the regulator machinery is housed. During one night, a flange of this steam pipeline became leaky without being immediately noticed, and thus, steam forced its way through the airshaft of the circulating cooling system that leads from the access room to the forward regulator machine room. This resulted in a total loss of the entire current gate controls of the forward regulator machinery compartment for the duration of several days. After the clean-up and drying-out of the control cabinets, almost all remote controls had to be recalibrated and that required a long time.

It must be guaranteed that no steam pipes are laid into the access rooms that are connected to the weapon compartments via ventilation, cooling etc.

85. Designation changes of the regulator machinery compartments.

The compartments which at this time house the amplifier equipment for the Flak and rangefinder remote controls, are designated: “Regulator Machinery Compartment”.

This designation is not appropriate. The main purpose of these compartments is the housing of the amplifier cabinets (current gate amplifiers). The still present GV [?]-aggregates [transformers], which are also considered amplifier equipment, are presently in separate adjacent rooms.

It is proposed that, for the entire compartment, analogous to the surface target artillery, be given the following chosen designation: “Forward, i.e., Aft Flak-Amplifier Compartment”.

In this compartment, all amplifier equipment for the Flak is to be housed in a convenient manner, that is, also those that are still in the Flak computer station (elevation transfer) and in the Flak switching station (targeting control, lateral lead control).

C. Flak telephone system.

86. Basic layout of the Flak telephone system.

The basic layout and allocation of the individual Flak telephone facilities for the individual battle-stations and their intended use overall, does not reflect military needs in many cases.

It has been repeatedly observed aboard ships that Flak telephone facilities, in particular the automatic systems, are used for entirely different purposes than for what they were originally intended. For example, aboard the battleship “Bismarck”, the Flak command telephone equipment is used as the Flak deployment telephone unit, since the weapons deployment telephone system is completely occupied by the surface target artillery system. Consequently, the weapons traffic telephone system is still being used as the Flak command telephone system. Since the distribution was done according to a plan for the stations based on the originally intended purposes of the individual installations, the present distribution of the connectors only partially meets military demands.

Often, the present remedy was to accommodate the wishes of the individual commands as far as possible. Therefore, the installations aboard individual ships are no longer uniform.

The basic structure of the modern Flak telephone system relates back to the prior proposal (The Flak Primer manual) that was previously made in AVKS report no. 200 secret, RI of 20 February 1935. Since conditions have changed considerably in the interim, and new insights have been obtained from war experiences, the re-evaluation of this important question is definitely required.

The AVKS must refrain from taking a comprehensive position because it does not have a Flak expert with sufficient onboard experience at its disposal. Nevertheless, it is proposed to submit the entire bulk of questions to a panel of experts with frontline experience and of professional authorities so that they can conduct a new comprehensive analysis.

87. Expansion of the weapons telephone-traffic facility [Waffenverkehrsfernsprechanlage].

It has become necessary to provide a connection at the foretop gallery for the weapons telephone traffic system. At this time, it is impossible for the Flak deployment commander and the technical personnel present on the foretop gallery to communicate instantly with the weapons operation rooms in case of a malfunction report.

Furthermore, it is deemed necessary to install an auxiliary connection for the weapons telephone traffic system in the operational compartments of the Flak stations A and B. The present telephone connection of the Flak command posts is now in the rotary ring compartment. Since both compartments are spatially separated, there is at present no manner of communication between them.

88. Telephone jacks for the aft reserve Flak battle station.

Since the aft reserve Flak command station is separated physically from the aft night command post, the telephone connections that are present there cannot be used. Therefore, an additional connection in the aft reserve Flak deployment station must be made to connect the weapons deployment with the ship’s command, artillery command, and for the weapons telephone traffic to the weapons operation rooms.

89. Signal facility for Flak deployment.

The humming sound system proposed in the final report of “Prinz Eugen” that would superimpose humming sounds on the Flak command telephone at “Cease, battery cease” i.e., at “Change, target change” was put aboard the battleship “Bismarck” as an experimental device for the AVKS tests. During the conduct of the Flak firing tests this system basically proved itself. However, the humming sound must be increased in intensity so that it can be more easily differentiated from voice sounds.

D. Heavy Flak guns.

90. Battery layout.

The layout of the battery into 4 groups of 2 x 10.5 cm twin Flak mounts each is advantageous and is overall proper for the demands of combat.
The Flak protective screen facing forward is relatively weak.
The spatial accommodations at the guns are, in part, quite tight, especially in the abeam firing direction.
The completed enlargement of the platforms of the 4 aft Flak positions (twin mount C/37) has proved itself as being necessary.
The fitting-out with two different types of mounts (twin mount C/31 and C/37), due to special conditions, has considerable operational disadvantages.
For more information, see cipher 92. and 93. An early compliance to arms uniformity is urgently requested.

91. Assembly of the 10.5 cm rapid loading gun C/33 in the 10.5 cm twin mount C/37.

The twin mount C/37 offers more space within the protective shield in contrast with the C/31. The operation and overview of the gun is therefore improved.
The design of the sequential indicator systems is more clearly visible.

The newly constructed sights (suspended alignment disc [circle]) achieved a simplification in the aiming system. It provides larger viewing apertures for the alignment crew. The capture of the target during direct aiming is facilitated considerably in comparison with the C/31 twin mount. The flip-in of the auxiliary sight from the outside by a special operator is no longer required.

By contrast, the large sighting notches have a disadvantage in that the sensitive parts of the gun’s fire command facility and the alignment machinery are exposed to heavier amounts of boarding sea spray and that the aligners, namely during direct alignment, are severely impaired in their work by the apparent wind.

The sight design with a moveable ocular requires that the alignment crew must constantly alter their body position during changes in elevation angle. The oculars move a distance of 21 cm during the raising of the barrel from the lower to the upper extreme position. Since the seats do not have springs, the aligner has to compensate for this large movement with his body contortions. It must be requested that the pivot of the sight optics viewer be relocated to the level of the neck of the aligner.

92. Missing lateral lead converter.

On the twin mount C/37, the slider hand-wheel on the gun moves the aiming telescope in the suspended aiming circle according to the dialed-in slider value that is indicated on the slider receiver. Since no lateral lead converter is present, the computed value for the horizontal plane obtained from the Reg calculator is erroneously entered as the slider value in the slant range plane in the sighting device.

This indicates that it is presently impossible to fire by “slider indicator” at aerial targets when switching the twin mount C/37 from the Reg and Flak command stations. This means that after failure of the alignment angle and elevation angle, these guns can only be fired by direct aiming methods according to the “correction indicator and slider via the telephone”. Remediation by the installation of a lateral lead converter on the guns for the recalculation of the horizontal slider into the slant slider is urgently necessary.

This matter has already been further investigated in AVKS report no. 185 secret TI of 13 February 1941.

93. Sight end-position switching [Visierendlagenschalter] of the 10.5 cm twin mount C/37.

As has already been reported in AVKS report no. 191 secret TI of 28 February 41, very serious deficiencies were found in the sight end-position of the switches of the 10.5 cm twin mount C/37 that severely restrict the elevation range of the guns during remote control operation.

The sight end-position switches are set with such great reliability (large switch handle) that they deactivate the elevation remote control over a wide range of settings. The following data for the switch settings on the gun were determined: A setting of 0 degrees in the lower sight end-position represents actually - 4 degrees. After activation of the lower sight end-position switch, a movement of the barrels by the remote control systems (i.e., at fully automatic, at semi-automatic and manual mechanical control) was only possible in the upward position, since the downward mobility is being blocked. In order to put the end-position switch back into the “number one” position, and to achieve a remote control operation into both directions, the barrels must first of all be raised up to a considerable elevation angle. This angle amounted to 28 degrees. This indicates that at the setting of an angle correction of say 15 degrees, the lower sight end-position switch is already at +11 degrees and the barrel must first be raised to more than 39 degrees in order for the gun to be under remote control operation and so that it can again work in both directions of movement. Since the upper sight end-position switches have similar problems, the elevation range is even more impaired, although the remote control operation in both directions is unaffected.

Based on the faulty conditions described, firing at sea targets or firing against low-flying aircraft with the 10.5 cm S.K. C/33 in the C/37 twin mount is practically impossible by direct aiming of the guns with the available mechanical elevation alignment devices.

Measures of amelioration have already been issued by the OKM A Wa [ordnance section] B d 4442/41 of 25 March 1941. The contemplated modifications could not be tested, since they had not been conducted before the end of the AVKS testing time.

94. Edge angle drive [Kantwinkelantrieb] of the 10.5 cm rapid-loading gun C/33 in the 10.5 cm twin mount C/37.

Repeated failures of the edge angle drive of the twin mount C/37, led to complete jams of the guns in the edge angle axle. [“Kantwinkel” or edge angle is the angle that is parallel with the gun’s “bedding” on the ship and is perpendicular to the elevation angle].

The initiated investigations led to the following results:

The edge-angle alignment mechanism of the twin Flak in the C/37 mount is, in contrast with the twin Flak in the mount C/31, mounted in such a way that in the manual alignment drive there is a worm-gear (for absorption of the recoil); while in the remote control drive, there is a direct transmittance of the edge-angle via cog drives. The transition from manual operation to remote control operation, and in reverse, is done by an operator throwing a recoil-spring coupling lever. However, this does not activate the final connection itself. The activation of the coupling lever causes only the tensioning of the spring in the coupling drive. Only the force of the spring causes an on or off engagement of the coupling device, and only then, when coupling jaws are in the proper position. In order to perform the coupling operation properly, the hand-wheel must first be moved back and forth so that the coupling can properly engage before throwing the recoil spring lever for tensioning of the spring.

The coupling equipment consists of a total of 2 different couplings, of which one is in the drive train for manual alignment and the other is seated in the remote control drive train. The coupling positions overlap so much that, for example, during the transition from manual alignment to remote control operation, the coupling in the remote control drive is already engaged when the coupling for the manual operation is not yet disengaged.

The remote control motor is equipped with a spring brake which has the purpose of effectively braking the control motor and thus the entire edge-angle mechanism in case of a current loss in the remote control drive. The brake also “speaks” when the safety switch is open, i.e., when shifting from manual to remote operation is not yet completely done.

In the event that the coupling rods are very stiff, the possibility exists that the coupling is only engaged up to the overlap, and then the spring does not have the power to complete the shifting. Thus, both drives are engaged, and since the motor brake is fully engaged as long as the safety switch is open, both drives are blocking each other.

On the other hand, if the safety switch is not calibrated so that closes only after the coupling is securely engaged in the drive train for manual alignment, and when the operating switch is engaged before shifting, then the remote control motor works in reverse against the worm-gear and freezes it up so completely that it cannot be moved by hand nor by remote control. The reactivation of the edge-angle alignment drive is only possible after the motor brake has been loosened.

In order to prevent further problems with the gun, first of all, the magnetic brake of the control motors and the spring in the coupling rods was removed. No further problems occurred after the removal of the brakes.

Further remedial measures have been decreed in the meantime with OKM A Wa Ba 6401 secret of 21 March 1941.

95. Performance rating of the Flak elevation remote control [Flak-Höhenfernsteuerung].

In a continuation of testing the Flak elevation remote control, which had been started aboard the cruiser “Prinz Eugen”, oscillographic measurements were made. Since tests could not be conducted in a rolling ship due to a lack of sea motion, the tests were limited by using an artificial rolling motion device [???].

The actual results indicate that aboard “Bismarck” the performance rating of the elevation remote control alone is better than the score that was given at the time of the cruiser “Prinz Eugen” tests, based on the entire remote control errors. The average error band [tracing?] of the remote control consists of about 25/16 degrees when the sine transmitter is set at the maximal speed of 8 degrees per second. No adverse influences were detected during the power system control for target elevation. It can, therefore, be concluded that the noisy process of stabilization that occurred aboard the cruiser “Prinz Eugen’s” Flak gun, (see AVKS special report, report no. 1260 secret TIII of 20 December 1940), can be traced back to the inadequate control characteristics of the controls for tilt and edge angle in the Flak command post itself.

The precise test results that were recorded in oscillograms will be presented in a special report AVKS report n. 721 secret/41.

96. Performance rating of the Flak edge angle remote control [Flak-Kantwinkelfernsteuerung].

Tests with the sine scope showed that the error of the Flak edge angle remote control amounts to an average of +/- 1/16 degree at a maximal speed of 6 degrees/second.

In regard to the progression of the error and the influence on the edge angle remote control by the preset remote control at the Flak command station, basically, the same problem is present as was described for the Flak elevation remote control (see #95 above).

The final results will be presented in a special report AVKS report no. 722 secret/41.

97. Examination of the behavior of the edge angle mechanical movement [Kantrichtwerkes] of the 10.5 cm twin mount C/37 during a unilateral shot.

In order to determine the behavior of the edge angle mechanical movement under remote control operation during firing with a single barrel at high elevation, oscillographic test were made during the firing with battle charges.

A preliminary assessment of the results show that the cant of the gun under remote control operation doesn’t occur until the projectile has left the barrel. The ascertained cant angle amounts to +/- 2/16 degrees. These oscillation events start to fade just 1 second after the instant of firing.

The simultaneously maximal motor current during the test was 21 Amp.
The presentation of the recorded oscillograms will be made in the special report referred to in cipher 95.

98. Interdependency of switching the elevation value receiver [Hw-Empfängers] on the mode of alignment.

During the switchover, using the remote control selector switch on the gun, from “Automatic Operation” (barrel elevation remote control) to “Superimposed [override] Operation” and “Auxiliary Operation”, the elevation value receiver is turned off via a relay that is located in a switching cabinet in the Flak switching station.

Basically, it is required that switching the elevation value receiver is independent of the selected mode of alignment and that the elevation value receiver always remains switched-on. In addition, the elevation value receiver must still be operational in the “Override Operation” mode. For example, when there is a defect in the remote control selector switch and the fully automatic control is no longer operational, but the tilt angle transmittance is still clear, the gun can still be aligned for tilt angle remotely and the target height + elevation angle can still be superimposed on the tilt angle by the elevation value receiver. This alignment mode is basically the same as used by the Flak elevation remote control type II (small cruisers and armored cruisers), and it has proven to be very effective.

The switch-off of the elevation value receiver aboard the battleship “Bismarck” was reversed, in that the appropriate clamps [terminals] of the remote control selector switch were bridged and the relays present in the switching station were removed. These switching changes make the structure of the remote controls much simpler and clearer. In addition, there is a considerable saving of materials (cables, relays, switch contacts) by the omission of these switches.

99. Starters for the Pittler-Thoma [electro-hydraulic] drives.

A new starter for the Pittler-Thoma drives was experimentally installed on one of the guns. The main difference, in contrast to the past starter design, is that the motor is started in two stages by parallel relays in armature circuits which are turned off by the armature resistance. The zero current relay, which is directly connected to the starter and which resets itself to zero when there is a drop in current, i.e., a drop during the shock from firing, the same as has been previously used in starters, is no longer installed. A motor stoppage due to the breakdown of the starter from firing shocks is no longer a problem with the new starter switch.

100. Switch-over clutch [connectors] in the barrel elevation drive mechanism.

In contrast with the edge angle drive, in the manual drive, i.e., the remote control drive of the barrel elevation drive, the two clutches do not overlap themselves. During shifting from manual operation to mechanical operation or the opposite, one half of the clutch is already completely disengaged before the other clutch engages. If, for example, in shifting to remote control operation both clutch halves are not positioned right across from each other in the remote control drive, and if after disengaging the manual drive, the remote control drive is not immediately engaged, then it is not possible to engage the jaws by turning of the hand-wheel because the manual drive has already been disconnected. If the remote control is switched on at this stage, the elevation alignment motor starts to run with a certain speed. This speed is in most instances so great that the clutch does not have time to engage. Then, both clutch halves slide past each other with a loud buzzing noise.

The engagement of the clutch only then occurs when the motor runs very slowly. To achieve low speed, there is presently a handbrake built along the motor driveshaft. However, this device has not been effective.

As a further aid to facilitate the shifting, a knurled wheel [friction wheel?] has been attached on the drive shaft. However, this is attached very clumsily; the elevation aligner, who has to perform the shifting procedure, can barely operate it and it is never used.

In order to achieve a flawless shifting procedure, it is proposed to plan the attachment and design of a friction wheel in such a manner that easy operation is possible. Furthermore, it is proposed that both clutches receive an overlap similar to the edge angle drive in order to disengage the clutch only when the other is already engaged. In this context, the remote control safety switch must be calibrated so that remote operation can be performed only when it is activated after the shifting procedure has been completed. Since, in contrast to the edge angle drive, the barrel elevation drive has a worm-gear that is located behind the junction of the manual alignment drive and the remote control drive, and thus the clutch overlap presents a danger that can lead to the jamming of the elevation alignment drive; which could not happen with the edge drive.

101. Disassembly [removal] of the SFS switch.

Again, repeated failures of the SFS switches have occurred during Flak firing practice that were traced invariably to the awkwardness of the switch.

The switch is exposed to severe weather and is always very heavily greased. But when the grease hardens after a while, especially in cold weather, the spring in the switch is no longer strong enough to activate the switch effectively.

In order to totally avoid this failure, it is proposed that the SFS switch be removed from the Flak guns. Since the firing is already mechanically secured when the breech is open, such a redundant safety feature of the SFS switch is not considered important. The interruption of the lighting and loading orifice by the SFS switch can be omitted. Even if centralized firing is introduced in the future, the switch is not necessary since a ready report is not used during Flak firing.

E. Light Flak guns.

102. Configuration of the light Flak guns.

The coordination of the light Flak guns into 4 separate groups of 2 x 3.7 cm twin Flak each, and forward 6 x 2 cm each, and aft 3 x 2 cm Flak each, is logical.
The placement of the individual guns itself, however, cannot be considered completely effective.

The placement of the 3.7 cm twin Flak of both forward groups is inadequate. Both port and starboard No. I 3.7 cm twin Flak are severely exposed to the seas. Their sweep angles are, furthermore, considerably impaired in the dead ahead direction by the forward heavy artillery turrets.
Even more unsatisfactory is the location of both No. II 3.7 cm twin Flak. These have such a limited sweep angle due to the rangefinder rotary dome of the forward command post, the spheroid Flak command posts, signal lines etc., that one can count on their effective deployment only on the rarest occasions. The transplanting of these guns to the upper bridge deck has since been approved.

The placement of two quad mounts with 2 cm Flak C/38 on the forward searchlight deck is heartily endorsed. The previously fairly weak forward Flak protection is herewith greatly improved.

In taking into account the great difficulty in finding suitable locations with good sweep angles for light Flak guns, it is proposed that the location of light Flak with multiple mounts be on the higher heavy artillery turrets in all new ship construction.

103. Ammunition transport facility for the light Flak.

Reference is made to EKK [Testing Command for New Ship Construction] G 6236 Wa O of 18 December 1940 regarding the ammunition transport equipment.

The previous and present ammunition transport facility for the new 2 cm quad mounts must be – in view of their rapid firing speed – considered completely insufficient. The transport path is very awkward because the ammunition load must be transferred twice. In addition, the ammunitions elevator, which terminates on the lower mast deck, is impeded by the forward rangefinder. The guide tracks that are mounted to the transport elevator shaft had to be shortened because the rangefinder hit them. The consequence of this is that the elevator's lower level can no longer be unloaded and only the upper level can be still used. An improvement is urgently required.

F. Instructions and drawings.

104. Content and design of the descriptive material.

It has again been noted that the instructions and drawings that were placed onboard were not adequate. Even a half year after commissioning the ship, the documentation for the Flak facilities was still missing in large part.

The request that the ship commands be equipped in a timely manner with sufficient instructions and drawings must be repeated with concern.

Proposed corrections for the instructions and drawings that were placed onboard, have already been submitted with AVKS report no. 371 secret TII of 8 April 1941.

IV. RANGEFINDER [EM] FACILITY.

105. General comments.

The rangefinder equipment has been upgraded compared with “Gneisenau” by the addition of a second foremast instrument as well as two 6.5 m directional rangefinders [REm] in the central 15 cm turrets. This is numerically sufficient.

During the testing period some of the assigned equipment was still missing, i.e., the 6.5 m rangefinders of the 15 cm turrets, and both radar [Em-II] instruments in the rotary dome of the fore and aft command posts were not operationally clear.

The limited usefulness of the 10 m rangefinder [RU Em] in the lower 38 cm turrets, because of their decreased eye-level plane, etc., has been demonstrated again. Basically, the rangefinder [Em] equipment of the lower turrets [Anton, Dora] can be omitted in new constructions. The installation of a rangefinder in turret A, which still had not been done, can certainly be abandoned.

The housing of the radar [Em-II] instrument together with the rangefinder [Em-I] instrument in a single rotary dome, as it is presently the case, is not an ideal permanent solution. It is not logical to combine the radar [Em-II] instrument with its specifications as a tactical search instrument as well as a fully operational artillery measurement instrument, with the 10 m rangefinder [Em-I] instrument, which is the most important optical measurement device. Rangefinder [Em-I] and radar [Em-II] instruments must at least be independent from one another in their deployment in the foretop. Therefore, it is proposed that in future constructions, they would be stacked as two independent rotary domes.

The foremast instrument is heavily impaired in its use, since it has no protection whatsoever against wind and weather. Referral is made to the various frontline reports of the ships with Atlantic experience in this matter.

The rangefinder [Em] equipment of the central 15 cm turrets cannot as yet be judged, since it was not yet aboard.

106. Fundamentals of position-finding.

It is a fact that practically all the position-finding results obtained at the frontline are unsatisfactory and do not meet the expected theoretical performance of the available instruments. There is now no doubt that this problem of the past few years is due to the lack of opportunity for systematic position-finding tests to be carried out in sufficient measure to gain practical experience.

The lack of a designated AVKS ship [research vessel] has proved to be especially disadvantageous. During recent years, the AVKS periods aboard new frontline ships were naturally too brief, and opportunity was lacking to conduct such systematic and thorough position-finding tests as was deemed appropriate. Also, the level of training aboard these newly commissioned ships did not allow for objective comparative experiments.

Unfortunately, there is no opportunity at the schools for the further practical development of solving position-finding questions. Furthermore, there is an arbitrary division in the training of range-finding and position-fixing. This is because the pure rangefinder training is done by the weapon command training group, while training on position-fixing equipment is done elsewhere.

The reasons for the unsatisfactory results for practical position-finding will be discussed further. Some see the main reason for the problems are in the present range-finding method itself. The need to obtain “running” data by staying in continuous contact is considered to be basically wrong. Currently, the rangefinder observer, first of all, tries to get a good curve [plot]. He is glued to the laboriously adjusted (but only intuitively correct) rangefinder and, as a result, he reacts too late most of the time when the distance differential [EU = Entfernung Unterschied] changes due to a maneuver of his own ship or that of the target. Such a finagled plot [Mogelkurve = finagled curve] may seem to ease the task of the tangent aligner at the firing data computer, but that is at the expense of accuracy. By contrast, rangefinder data derived with spotting [point] contacts, i.e., when only points of optimal measurement are used, results in a more correct plot. The contact point plot allows satisfactory tangent plotting most of the time (this actually occurred aboard “Bismarck” during practical position-fixing exercises) even when no permanent curve arises for the tangent plotter.

Another source considers the main cause for unsatisfactory position plotting to be related to the use of the parallel catch instead of the previous light pointer tangent in the firing data computer, which has now caused an unavoidable separation between the rangefinder indicator and the tangent former [?]. (see e.g., Artillery technical report “Admiral Hipper” report no. secret 951 of 9 March 1941.

For all these questions, there is presently no sufficient and definitive resolution possible. However, as described above, systematic position-fixing tests are mandatory. As long as there is no AVKS-ship made [facility] available, it is suggested that experiments be performed at the rangefinder school, which must be equipped with the latest position-finding equipment (firing value computer).

Regarding the rangefinder testing and position-finding exercises conducted by the AVKS aboard “Bismarck”, which, in the first place, focused on testing the radar [Em-II] instrument, a special report will be made.

107. Equipment of the rangefinder rotary domes.

108. Azimuth control [Seitensteuerung] of the rangefinder [Em] rotary domes.

109. Azimuth drive control of the rangefinder instruments in the turrets.

There was no opportunity for testing the rangefinder manual mechanical drive controls by the recently installed new rotation momentum amplifier.

In general, it can be noted that the operational readiness, and also the workings of the control mechanism installed in the turret rangefinder azimuth drive control, measures up to requirements. Whether a drive control assisted by a rotation momentum amplifier , i.e., this primarily means the mechanical amplification of the azimuth drive control or the built-in electrical amplifiers for the azimuth drive control of the battleships “Scharnhorst” and “Gneisenau”, is preferable, can only be assessed after prolonged operation. Attention is directed to the recommended maintenance of the rotation momentum amplifiers.

Failures in these control components did not arise during the test period.

A reverse [backup] differential setting for the switch-off of turret movement, based on further experience, appears to be unnecessary.

110. Adjustment feasibility for the 3 m rangefinder [REm].

Die an dem 3 m REm vorgeschene Einrichtung zur Ausschaltung des persönlichen Fehlers ist an sich zweckmäßig.

The adjustment permanence of the instrument is sufficient, according to previous and recent experience.

There is currently a lack of opportunity for making adjustments at sea, when no target is present with a known distance, and this uncertainty concerning making adjustments, influenced by the uncertain and changing values of personal prejudices [errors], is considered unacceptable.

111. Elevation stabilization of the 3 m rangefinder [REm].

The elevation stabilization of the 3 m rangefinder already shows a considerable drift at changes of course at slow speed. However, the drift is so steady that a manual re-adjustment of the elevation can be readily accomplished.

The drift resulted in a maximal drift speed deviation of 0.5/16th degrees/second, at a course change of 42 degrees/minute and an average speed of 10 knots.

The recorded stabilization diagrams and other experimental results have already been submitted in a special report of the stabilization tests of the rangefinder stations [Ewastandes?], report no. 619 secret of 10 April 1941.

It was observed that in both Ewa stations [Ewaständen?] the zero setting (coarse feedback) was misadjusted by about 1 ½ degrees. Since the instruction on board gave no directions regarding the calibration methods, no recalibration could be made by the ship’s command.

112. Rw [alignment value or angle] indicator in the tripod chest of the 3 m rangefinder [REm].

The read-off of the Rw indicator is difficult because of the way it is attached. Since the Rw indicator provides the only possibility of determining the particular azimuth direction of the instrument, it is deemed necessary that the Rw indicator be mounted on the upper surface of the tripod chest [support box].

The pointer in the Rw indicator does not meet the general standards of the gunnery command. The already awkward read-off is made even more difficult by its poorly designed shape.

113. Distance transmittal [E-Übertragung].

The transmittal of the rangefinder instrument’s distance data to the computer instruments in the computer station [Rechenstelle], that is, to the other display instruments, is still made by an intermediate switch on the Anschütz amplifier control [Firma Anschütz GmBH, since 1995 part of Raytheon]. As far as is known, this solution was previously chosen because of the load considerations on the measuring hand-wheel by the proposed connection of two E displays to the rangefinder instrument (1 display for surface targets, 1 display for Flak). Now that the connection of the Flak to the surface target instruments has finally been abandoned, the Anschütz intermediate control appears to be superfluous. This deletion would remove one more source of potential breakdowns and make the data flow smoother and more concise.

114. Performance of the [radar] Em-II instrument.

The performance of the radar [Em-II] instrument was tested by measured-distance approaches against the cruiser “Emden” under variable conditions.
The tests were first of all concerned with its range, accuracy of the distance measurements, and the azimuth bearing. Furthermore, the suitability of using this instrument’s data as a basis for the artillery bearing and firing data computations was determined, and this was compared with the optical instrument data.
The results will be presented in a special report.

115. Integration of the radar [Em-II] instrument into the fire-control command.

Based on the experimental results, it is proposed that the radar [Em-II] instrument is to be permanently integrated in parallel with the other rangefinder measuring instruments of the artillery fire-control command.

Presently, aboard “Bismarck”, it was merely planned to transmit the distance data of either the rangefinder [Em-I] instrument or the radar [Em-II] instrument to the artillery fire-control command, depending on the setting of the alignment selector switch in the rotary dome. However, since there is only one Anschütz intermediate amplifier in the rotary dome, there is a necessity during the switch-over to the selected alignment station for the simultaneous re-plugging of a cable leading to the Anschütz intermediate amplifier, in order to select the desired rangefinder transmission [output] from either the Em-I or Em-II instrument. In order to carry out the comparative tests between the Em-I instrument and the Em-II instrument aboard “Bismarck” the AVKS built an experimental switch box. Special Siemens displays were built into the radar [Em-II] instrument and, in addition, the gear ratio was modified to 800:50 hm. This made it possible to lead the distance data via a special circuit cable directly, and also in parallel with the rangefinder [Em-I] data, to the main switchboard station and thus to the gunnery data computer [Schußwertrechner].

Furthermore, a special line was also led to the main switchboard station to facilitate the transmission of the AVKS target alignment data tests of the azimuth bearing instrument to the gunnery data computer.

This switching demonstrated that the radar [Em-II] instrument could be used as a distance measuring instrument as well as an aiming instrument (aiming display), and that it could be optionally switched to the distance and azimuth graphics of the gunnery data computer in a manner similar to that normally used with the optical rangefinders and target indicators.

Particulars of the experimental switching have been reported in AVKS report no. 482 secret TI of 8 January 1941.

The final transmittal of the aiming [target] direction data from the azimuth bearing instrument to the main alignment/elevation indicator [Rw/Hw-Geber] is best routed through the target indicator [Zielgeber], so that he can immediately take over the lateral [azimuth] alignment, as well as enter his own observation, without prior switching.

Special cases come to mind, such as when the commander himself makes out a target which he must engage first after opening fire or after a searchlight illumination [of a target], or that the commander suddenly sees a target himself in the pre-dawn that was previously only visible by radar [Em-II] instrument bearings. In such situations any switch-over must be avoided. The azimuth bearing instrument is, therefore, to be used only for target acquisition by the leading target indicator [Zielgeber]. As long as this target indicator cannot make out the target, he takes the aiming direction from the target direction receiver [ZRw-Empfänger] and transmits it to the leading alignment-elevation indicator [Rw-Hw-Geber], from where it can be picked up as a target designation by other target indicators [Zielgebern], aiming posts [Zielsäulen], and searchlight alignment instruments [Scheinwerferrichtgeräte].

The required switching system is shown in cipher 55.

116. Proposals for the modification of the radar [Em-II] instrument.

V. CONCLUDING REMARKS.

117. The completion of the arming of the battleships “Bismarck” and “Tirpitz” signifies an end of an epoch in the development of the artillery for the great ships.

In the following concluding remarks, a number of questions are listed concerning this era of the development of artillery, and these are briefly summarized; furthermore, the solution, i.e., continuation of development of the following are considered to be particularly important:

As deputy.

[signed]

von Goetze

EDITOR's note: Kapitän zur See (later Konteradmiral) Eberhard von Goetze (1893-1977) was Chief Inspector of Naval Gunnery at the Artillery Testing Command for Ships (AVKS).

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