CHAPTER 3 – U-900
14:36 (Berlin Time)
Thursday, March 25, 1943
Covered boathouse, Germaniawerft Shipyard
Kiel, German Baltic coast
Unlike the U-800, which Ulrich had first seen while it was still on its construction slip, the U-900 was already in the water, floating inside a completion boathouse that hid it from indiscrete eyes and cameras. Another nine similar boathouses, complete with gantry cranes and rail sidings along the quays, were either already built or under construction at the Germaniawerft Shipyard, the same shipyard that had built the U-800. That alone showed to Ulrich that the Kriegsmarine was giving a high priority indeed to the mass production of the new Type XXI submarines, of which the U-900 was the first to be completed. The other thing that was different was the fact that the civilian engineer leading him and his crew towards the gangway linking the quay of the boathouse to the deck of the submarine was not the late Otto Premingen, the genius who had designed the U-800 all by himself. Instead, it was another genius, Professor Hellmuth Walter, who was guiding him today. Walter was in fact talking about his predecessor as he walked beside Ulrich towards the gangway.
‘’I should have listened to Otto and helped him then to design the U-800, but I was fixed on my own projects at the time. However, when my prototypes showed the potential dangers of using perhydrol as a fuel at sea, I embraced Otto’s ideas and did my best to incorporate some of my better concepts to his own concepts. The U-900 is the result of that fusion of minds, Kapitän von Wittgenstein, and I can say without a doubt that it is even better than the U-800.’’
One look at the long, smoothly profiled shape of the U-900 was enough to make Ulrich believe the naval designer.
‘’I bet it is, Professor Walter. As much as the U-800 looked like a BMW sports car, the U-900 looks like a Maserati racer. The lines of the sail in particular look extremely efficient in hydrodynamic terms. The sail in fact looks as if it grew out of the hull and blends with it, rather than looking as if it was simply dropped on top of the hull.’’
‘’Indeed! Like Doctor Premingen, I was inspired by the body shape of sea mammals. Tests in both wind tunnels and water basins further helped us refine the shape of the U-900. I can tell you from the results of those tests that the U-900’s shape is eight percent more efficient hydro-dynamically than the shape of the U-800, while it is a full 56 percent more efficient than the shape of a Type IX submarine when submerged.’’
‘’But we did find that there was a price to pay for that in terms of top speed on the surface, Professor Walter. The sea trials of the U-800 showed us that its hull shape, while highly efficient when submerged, limited its speed on the surface, due to the water flowing over and around the forward top deck. As a result, the U-800 could not go faster than 13.5 knots on the surface, even though it could attain 31 knots when dived.’’
‘’True! Me and my design team worked long and hard to find a way to improve the top surface speed of the design. The breakthrough came from a young engineer who had watched his son make paper planes out of a folded sheet of paper.’’
Ulrich stopped in his tracks and did a double take on hearing that.
‘’Paper planes? I don’t understand.’’
‘’It is actually devilishly simple, Herr Kapitän. In fact, many of the best ideas are devilishly simple. What my young engineer realized while watching his son play was that two-dimensional flat surfaces, like a sheet of paper, can easily be folded to form a multitude of possible three-dimensional shapes, like the vertical rudder of a plane. In this case, we took that idea and designed a system of two very slightly curved steel plates of the appropriate shape and size that married smoothly into the bow outer top casing of the hull of the U-900 when it navigated submerged. However, once on the surface and ready to proceed at speed, those two plates, which are hinged at their base, pivot up and come together along their forward edges, essentially forming a classic surface ship’s ‘Atlantic’ bow shape. When speeding on the surface, the water pushed by the massive bow of the U-900, instead of running over the outer top deck and making the boat pitch down, is split apart by this ‘false bow’ and flows along the sides, like in the case of a surface ship. The tests in water basins showed us that our false bow should allow the U-900 to attain about fifteen or sixteen knots on diesel power on the surface, or over twenty knots on electric motor power.’’
Ulrich couldn’t help fix Walter in disbelief.
‘’Twenty knots on the surface? That would be truly fantastic!’’
‘’Isn’t it?’’ replied Hellmuth Walter, smiling, before resuming his walk. ‘’Anyway, you will find plenty of other incredible things about the U-900 during this tour.’’
More than two hours later, the group of 65 men emerged back on the top deck of the U-900, coming out of a water-tight steel door at the front of the sail. While the enlisted men and junior officers of his crew were chatting enthusiastically about what they had seen and learned inside, Ulrich was nearly stricken dumb by the fantastic capabilities of his new submarine. He then smiled warmly to Walter while shaking vigorously his hand.
‘’Professor, you have designed a true masterpiece. With such an instrument in the hands of my crew, we will be able to cut Great-Britain off from its maritime supply lifelines.’’
‘’Well, if you can achieve that and force the British to sue for peace, then I will consider myself plenty happy, Herr Kapitän. I will follow closely the results of your sea trials. If you encounter any kind of problem, tell me at once.’’
‘’I certainly will, Professor Walter.’’ promised Ulrich before leaving the boathouse with his crew and heading towards the barracks building that had been assigned to them on arrival in Kiel.
The next five weeks were busy ones for Ulrich and his men, with three weeks of familiarization training on the U-900’s systems, followed by two weeks of condensed sea trials to test the various parts of the new submarine and its actual performances. Those last two weeks pointed at a handful of small problems that took only a few days to correct, but also revealed quite a few pleasant surprises. For one thing, the so-called ‘false bow’ system more than fulfilled its promises, with an actual top speed on the surface and in moderate seas of sixteen knots on diesel power and of 22 knots on electric motors, a performance that left Ulrich truly ecstatic. Top submerged speed also proved exceptional, beating even the U-800’s own performance with a record-breaking speed underwater of 32 knots. However, the greatest surprise had come when, on Admiral Dönitz’ request, a Luftwaffe maritime reconnaissance bomber equipped with one of the new centimetric radars flew in the area where the U-900 was sailing, in order to assess its vulnerability to aerial radar detection. To everybody’s shocked surprise, that bomber wasn’t able at first to see the U-900 on its radar, even though the submarine was on the surface and going at twelve knots. The aircraft had to get as close as four kilometers from the U-900 before it could start to detect it on its radar. Even then, that radar signature was no bigger than that of a periscope head sticking out of the water. Many German radar experts scratched their heads about that but could not figure out how that could be possible. What they couldn’t know was that the racy, smooth lines of the submarine, with its sail blending with the hull, did a lot more than simply cut underwater drag: they also mimicked the radar-avoiding shapes of what was going to be called decades later ‘stealth technology’, with smooth hull and superstructure surfaces canted inward and with no right angle corners that would reflect strongly radar waves. The final result was a radar signature cut by 84 percent compared to that of a Type IX navigating on the surface, something that made Admiral Dönitz very happy indeed. Then came the time to prepare for the first war patrol of the U-900.
10:05 (Berlin Time)
Saturday, May 8, 1943
U-900’s boathouse, Germaniawerft Shipyards
Kiel, German Baltic coast
Ulrich was standing on the forward weather deck of his submarine, watching his men help load a huge 610mm diameter Japanese Type 93 LONG LANCE torpedo into its launch tube, situated outside of the submarine’s pressure hull, when Admiral Dönitz showed up with a staff officer, making Ulrich and his men come to attention and salute. Dönitz, returning first their salute, then made a dismissive gesture.
‘’Please, at ease, men! Continue your work as if I was not there.’’
The admiral and his aide then stood to one side of Ulrich, watching like him the loading of the big torpedo.
‘’I must say that adopting and then producing under license the Japanese Type 93 and Type 96 torpedoes was one smart move on our part. Thank God that the Fuhrer immediately accepted the idea of adopting those Japanese designs: that cut a lot of opposition to it. Now, your submarine will be the first one designed from the start to be able to use all models of German and Japanese torpedoes.’’
‘’It won’t be alone in that for long, Admiral: the second boat of the class is now afloat and completed, while the third and fourth ones are also afloat but still under completion.’’
‘’True! But those Type 93 and Type 96 torpedoes will give you weapons that are fast enough to catch even destroyers. With some of our first T5 ZAUNKÖNING acoustic homing torpedoes also aboard your submarine, you should be able to create some serious mayhem in the enemy’s maritime lines of communication.’’
‘’I am confident that I will be able to make the next few weeks quite unpleasant indeed for the enemy, Admiral.’’
‘’That’s the spirit! By the way, here are your sealed mission orders: you will depart on patrol as soon as all your supplies and munitions have been loaded aboard.’’
‘’Danke, Herr Admiral!’’ said Ulrich at the same time he took the large but thin envelope offered by Dönitz. ‘’May I ask in which area of the World you are sending me?’’
The admiral had a sarcastic smile as he answered him.
‘’You will be close enough to England to smell Fish and Chips from your boat, my dear Wittgenstein.’’