Trial requirements are reasonably complete, but available information indicates that trials were made considerably more exhaustive on the type XXI vessels then on earlier types such as the IXC vessels.  
          There is not very much information available as to the method for conducting tests.  
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          Trials and tactical data of the German submarines are outlined in trial books prepared for each class.  Trials of the ship were segregated from trials of torpedo tubes, guns, and electronic gear.  
          Available information consists of two trial books: one for types VII B and C and IX B and C, and one for type XXI.  
          The book for the VII and IX types is divided into several sections:  
          a)  A summary giving the dates on which each of the inspection and test items was conducted.  
          b)  A description of the preliminary survey items:  
                  1.  Inspection to determine compliance with specifications, with a list of documents to be presented at the time of inspection.  
                  2.  Docking inspection.  
                  3.  General inspection.  
                  4.  Preliminary surface trials.  
          c)  Final acceptance.  
                  1.  Preliminary trim experiment.  
                  2.  Final trim experiment.  
                  3.  Surface measured mile runs.  
                  4.  Submerged measured mile runs.  
                  5.  Four hour surface run with main motors.  
                  6.  Fuel oil consumption runs.  
                  7.  24-hour endurance runs, and related fuel oil measurement, lub oil measurement.  
                  8.  Maneuvering on diesel engines, and related  
                               reversing time  
                               test of safety devices on sudden release of load.  
                  9.  Maneuvering on main motors.  
                  10.  Determination of mechanical losses, in main propulsion systems  
                               in main propulsion systems, and  
                               determining lowest main engine rpms.  
                  11.  Starting engines, and tightness test of exhaust valves, test of hand reversing gear.  
                  12.  Underway dive without negative tank.  
                  13.  Underway dive with negative tank.  
                  14.  Tightness inspection at 30 meters.  
                  15.  Pressure dock test to 120 meters, with related deflection and bending measurements, inspection of water closets, pressure tanks etc., hand operation of rudder and shafts.  
   - 1 -


                  16.  Fuel ballast tank leak test.  
                  17.  H.P. blow test at 12 meters.  
                  18.  L.P. blow (exhaust gas blow test).  
                  19.  Flooding time for regulating tanks.  
                  20.  Flooding time for WRT tanks.  
                  21.  Blowing time for regulating tanks.  
                  22.  Blowing time for WRT tanks.  
                  23.  Trimming time with compressed air.  
                  24.  Drain system operations from regulating tanks and bilges with main and auxiliary pumps.  
                  25.  Drain system pump tests against 100 meter discharge head for main pump, and 30 meters for auxiliary pumps.  
                  26.  Auxiliary trim and drain pump tests.  
                  27.  Auxiliary trim and drain pump test against a discharge head of 100 meters.  
                  28.  Trim rating of auxiliary trim and drain pump.  
                  29.  Unused.  
                  30.  Rating test of standby C.W. and standby lub oil pump.  
                  31.  Operation of standby lub oil pump as a fuel oil transfer pump.  
                  32.  Fine adjustment of regulating tank flooding.  
                  33.  Submerged suction test of drain and trim pumps from trim tanks.  
                  34.  Same as 33, but from WRT tanks.  
                  35.  Power rudder operation.  
                  36.  Hand rudder operation.  
                  37.  Power plane operation.  
                  38.  Hand plane operation.  
                  39.  Compressor test.  
                  40.  Distilling plant test.  
                  41.  Periscope system operation.  
                  42.  Anchor handling test.  
                  43.  Towing arrangements test.  
                  44.  Torpedo and mine handling test.  
                  45.  Rapid loading of torpedo tube.  
                  46.  Not used.  
                  47.  Compartment ventilation.  
                  48.  Emergency blow test.  
                  49.  Test of secondary blow connections.  
                  50.  Emergency compartment air test.  
                  51.  Air renewing test.  
                  52.  Test of signal buoy and marker buoy release.  
                  53.  Report of tests on auxiliary motors under operating conditions.  
                  55.  Test of control of emergency lamps.  
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          d)  Signatures of officials certifying the tests.  
          e)  A group of curves, tables and charts bearing on the following:  
                  1.  Trimming experiment.  
                  2.  Surface measured mile data.  
                  3.  Surface fuel consumption.  
                  4.  Submerged measured mile data.  
                  5.  Submerged power requirements.  
                  6.  Speed-power curve.  
                  7.  Surface power data.  
                  8.  8-hour full power run data.  
                  9.  Engine maneuvering data.  
                  10.  Motor maneuvering data.  
                  11.  Diving data without negative.  
                  12.  Diving data with negative.  
                  13.  Ballast tank blowing data.  
                  14.  Regulating tank flooding data.  
                  15.  WRT flooding tank.  
                  16.  Blowing data on regulating tank and WRT.  
                  17.  Trimming with compressed air.  
                  18.  Surface and submerged operations, of trim and drain pumps.  
                  19.  Rudder maneuvering.  
                  20.  Plane handling.  
                  21.  Junkers compressor.  
                  22.  Periscope hoist operation.  
                  23.  Anchor handling data.  
                  24.  Towing release mechanism.  
                  25.  Auxiliary motor data.  
                  26.  Vibration dampening tests.  
                  27.  Summary of gun firing tests.  
           It will be seen that the detailed information does not cover the entire range of the tests.  The remainder of the trials are shown in the book merely as having been carried out on such and such a date.  
          Returning momentarily to part (a) above), this part also lists torpedo tube tests, torpedo target arrangements on the periscopes, compass and communications system tests as having been carried out on given dates by other agencies.  
          The trial book indicates that the trials are complete, but does not provide much detail as to the manner of conducting the trials.  These are apparently to be found in other text material and directives, according to the forward of the trial book.  
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