Heinkel Salamander

Heinkel Salamander

 

The He 162 had its genesis in a demand by the Jägerstab (Fighter Staff) for a Volksjäger (People's Fighter) that was simple, inexpensive and suitable for production by semi-skilled and unskilled labour out of non-strategic materials such as wood. It was to be powered by a single BMW 003 turbojet, weigh no more than 2000 kg (4410 lbs) fully loaded, carry an armament of one or two 30mm cannon, fly faster than 750 kph (466 mph), possess an endurance of 30 minutes at sea level and be able to take off in a distance less than 500 meters (1640 feet). This requirement was distributed to all the major aircraft companies on 8 Sep 1944 with responses due by 20 September so that mass production could commence 1 January! The Volksjäger concept was pushed by Party Leader Otto Saur, director of the Jägerstab and a protégé of Albert Speer, head of the Ministry of Armaments, over the vociferous objections of Adolf Galland, General der Jagdflieger (General of Day Fighters). Galland believed that all of Germany's remaining aircraft production facilities should be concentrated on proven aircraft such as the Me 262. He also didn't believe that pilots could be trained quickly enough to fly the aircraft in the numbers envisioned. Designers such as Kurt Tank and Willy Messerschmitt also objected to the project on the more technical grounds of a totally unrealistic specification and an absurdly short amount of time for design and preparations for production. Despite this opposition the submission date was actually advanced by 6 days to 14 September!

 

A Heinkel He 162A-2 of 1./JG 1 based at Leck airfield - Germany 1945

Proposals were received from Blohm und Voss, Arado, Focke-Wulf, and Heinkel when the first evaluations were made on 15 September, Messerschmitt having refused to submit a proposal. Focke-Wulf's proposal was deemed unrealistic, Arado's was completely rejected and Heinkel's was deemed unsuitable; while Blohm und Voss's was judged the best submitted. The Heinkel proposal unacceptable on 5 counts: a sea-level endurance of only 20 minutes; the unusual location of the engine on top of the fuselage would undoubtedly result in maintenance problems; it failed to meet the stipulated take-off requirement; it would take too long to dismantle for rail transport; and it was designed to carry 20mm cannon rather than the 30mm specified. Heinkel's representative protested that their proposal was being evaluated by standards other than those applied to the other proposals to the detriment of Heinkel's proposal. Another meeting was scheduled for 19 September to make a decision after all the proposals were re-evaluated.

By this time new proposals had been received from Junkers, Focke-Wulf, Siebel and Fiesler, but the result was much the same. Blohm und Voss's Projekt 211 was judged the best with Heinkel's as second-best.

It may well have been second-best, but it possessed one major advantage over the Blohm und Voss proposal; it was much further along in the design process. Heinkel had been working on a simple and unsophisticated jet fighter, the Spatz (Sparrow), since the early part of the summer and had even test-flown the BMW 003 in July to obtain necessary performance data. The effort to convert the Spatz into the Volksjäger was not inconsiderable, but it was far easier and faster than working from a clean sheet of paper as the others had to do.

On 23 September Heinkel showed a mock-up of their Volksjäger to officials while the decision was made to proceed with the Volksjäger concept in a meeting at Göring's headquarters that same day. It was decided that pilots would be recruited from the ranks of the Hitlerjugend (Hitler Youth). The boys would be taught to fly on the Volksjäger if they didn't already know how to fly and would finish their training by flying operational missions! Party Leader Saur favored Heinkel's Projekt 1073 over the Blohm und Voss Projekt 211 and ordered construction of the first prototype the next day on his own authority.

Heinkel had nearly carried the day, but it wasn't until two aerodynamicists were consulted that the partisans of the P.211 were finally defeated. They ventured the opinion that there might be a problem with the airflow of the engine inlet and this was enough that the Heinkel proposal was ordered into production at an initial rate of a thousand aircraft per month. The aircraft was originally designated the He 500, but this was quickly changed to the He 162, a number previously used by Messerschmitt's contender for the Schnellbomber (fast bomber) competition that had been won by the Ju 88. The project was code-named 'Salamander', this being often confused for the name of the aircraft itself.

The final drawings were complete by 29 October, one day ahead of schedule and the first prototypes were in an advanced stage of construction. The He 162 was unique in the history of aviation as the only aircraft in which development, pre-production prototypes and main production lines were started almost simultaneously and proceeded in parallel.

The production arrangements were quite complex and are an excellent example of the effort Germany had to make to minimize the vulnerability of her aviation industry. Little was it realized that this decentralization plan would play right into the hands of the Allies as the 8th Air Force executed its plan to destroy all German means of transport from railcars to river barges.

Final assembly was to be at 3 plants, Heinkel-Nord at Rostock-Marienhe, Junkers at Bernburg and Mittelwerke at Nordhausen; the first two being expected to assemble a thousand machines a month and the latter, two thousand. All wooden components were to be produced by two groups of wood-working and furniture-manufacturing firms specially organized the Erfurt and Stuttgart areas. Metal fuselages were to be built by Heinkel factories at Barth in Pomerania, Pütnitz in Mecklenburg, Stassfurt in Saxony and at Berlin-Oranienburg as well as the Junkers factories in Schönbeck, Ascherleben, Leopoldshall, Halberstadt and Bernburg. In addition fuselages were to be built in former salt mines at Eglen and Tarthun. The Heinkel factory at Wien-Schwechat was to handle construction of the prototypes and later to begin production in a converted chalk mine outside Vienna at Hinterbühl. Another salt mine near Urseurg housed the machinery from the Berlin-Spandau and Basdorf-Zülsdorf engine factories for the production of the BMW 003 engines. The production schedule called for the first thousand aircraft to be ready by the end of April 1945 and output to reach two thousand per month the following month. The He 162A was one of the most distinctive aircraft ever designed with its engine mounted above the fuselage and downward-drooping wing tips. The Heinkel design team had placed the engine in this unusual position to minimize any difficulties with the inlet and exhaust ducting, the aerodynamics of which were poorly understood.

In line with the semi-expendable nature of the Volksjäger, the He 162 was a rather spare design, but it did include a simple ejection seat as pilots were considered rather more valuable than the aircraft itself. It was essential as the chances of bailing out in the usual manner were considered less than optimal with the jet intake mounted right behind and above the cockpit.

The first prototype, the He 162 V1, made its initial flight on 6 December, 90 days from the receipt of the requirement! A record unparalleled for a modern combat aircraft. The flight was mostly uneventful except that a wooden landing-gear door was torn away during the high-speed portion of the flight. Four days later, the second flight ended in tragedy as the starboard wing leading edge separated from the aircraft which caused it to crash in front of large crowd of VIPs. The pilot did not survive. An investigation determined that the bonding agent for the wood was defective. It was a new adhesive that had to be used as the factory producing the usual bonding agent had been bombed out. The Ta 154 Moskito was cancelled because of this type of problem, but the He 162 program had too much political weight behind it to suffer a similar fate.

The second prototype flew on 22 December and others rapidly followed. It was initially to be armed with 2x 30mm MK 108 cannon, but the airframe proved to be too lightly built for such a heavy armament. Flight test revealed problems with lateral instability, snaking at high speeds and severe instability during left-hand high G turns. It also proved to need much more runway for take-off and landing than allowed by the specification. The tail surfaces were enlarged and the wing tips extended and drooped on the V3 and V4 prototypes in a successful effort to resolve most of these problems. Had time permitted the wing would have undoubtedly been fully redesigned rather than the expedient wing tip drooping.

Very few He 162A-1 aircraft were built with the 30mm cannon before production switched to the A-2 model armed with 2x 20mm MG 151 cannon. The A-2 also incorporated a number of aerodynamic changes to increase stability, but these were not fully successful as it remained very unforgiving of abrupt movements of the controls. The 162 had a very high rate of roll, but much care had to be taken as full rudder induced a lot of shudder and buffeting. Only three-quarters rudder could be used if a smooth turn was desired, such as when trying to shoot at an enemy! Experienced piston-engine pilot had to unlearn their habit of throwing themselves around the sky if they wished to master the 162 as it demanded smooth, flowing motions from its pilot. In brief the He 162 was a handful for experienced pilots and would have been a death-trap for the average Hitlerjugend pilot fresh from glider training.

The Luftwaffe formed Erprobungskommando (Evaluation Unit) 162 under Heinz Bär, the 8th leading ace of all time with 220 kills, in January '45 to evaluate the He 162 at the Rechlin test centre. By April Erprobungskommando 162 had joined Adolf Galland's band of disgruntled fighter pilots, JV 44, with its Me 262s at their base near München, but had little opportunity for combat as the 162 wasn't yet considered ready for action.

On 8 February I/JG 1 was ordered to turn over its Fw 190s to II/JG 1 and proceed to Parchim to begin conversion to the He 162, but their first aircraft didn't arrive until the end of the month. Later joined by the Geschwaderstab they stayed there until bombed out by the British on 8 April. They moved to a number of different airfields in North Germany to avoid being overrun by the advancing Allies ending the war at Leck in Schleswig-Holstein. II/JG 1 left their Fw 190s behind on 8 April as they transferred to Rostock to begin the conversion to the He 162, but joined the first Gruppe at Leck on 2 May to escape the Soviet advance. The conversion of III/JG 1 was planned to begin in mid-April, but it was disbanded on 24 April and its personnel were distributed to other units. On 3 May JG 1 was reorganized into two Gruppen, I (Einsatz [Combat]) and II (Sammel [Replacement]). They totalled some 50 pilots and aircraft in 6 staffeln.

I/JG 1 was declared combat-ready on 23 April, after it had already claimed one British fighter on 19 April. Feldwebel Günther Kirchner was credited with shooting down a fighter when the captured pilot admitted he'd been shot down by a jet. Unfortunately Kirchner himself was shot down shortly thereafter by another British fighter. At least two other claims were made by He 162 pilots before the end of the war, although only one Tempest V can be confirmed from British records since a number of British aircraft were lost to unknown causes at times and places that match these other claims. At least one and possibly three He 162s were lost to enemy action.

The BMW engine proved to be far less sensitive to throttle movements than those of the Me 262, though still prone to flameouts. This allowed the He 162 to be flown up to the limits of the pilot's confidence in the aircraft, unlike the Me 262 whose engines restricted much in the way of manoeuvres.

The He 162's primary drawback was its very short endurance of 30 minutes at sea-level. This forced the pilot to pay close attention to his fuel gauge and allowed little leeway for bad weather or enemy aircraft over the pilot's home airfield. In fact several of the operational losses can be attributed simply to running out of fuel.

Other problems were the lack of visibility above and to the rear and the inability of the tail to handle the maximum stress that the rudder could generate. The former would only really have been a problem if the 162 was at a low enough speed that it could be bounced by piston-engined fighters since the area obscured by the engine is the most vulnerable of any aircraft. The weakness of the tail instilled a lack of confidence in its pilots that the 162 could withstand extreme manoeuvres and they, therefore, were reluctant to do so lest it break-up in mid-air.

Despite all these caveats, the He 162 would have been a effective fighter in the hands of a trained pilot if the war had continued, easily superior to the best fighters fielded by the Allies, possibly even including the P-80A.

Specifications (Heinkel He 162A-2 Salamander)

Type: Single Seat Interceptor

Design: Ernst Heinkel Design Team.

Manufacturer: Ernst Heinkel AG. First batch Vienna-Schwechat. Production totally dispersed with underground assembly at Nordhausen (Mittelwerke), Bernberg (Junkers) and Rostock (Heinkel).

Powerplant: One 1,764 hp (800 kw) thrust BMW 003A-1 or E-2 Orkan single shaft turbojet engine.

Performance: Maximum speed 522 mph (840 km/h) at 19,685 ft (6000 m); service ceiling 39,500 ft (12040 m). Endurance 57 minutes at 35,990 (10970m). Climb rate 3,780 ft/min (19.2m /sec) at sea level - 1,950 ft/min (9.9m /sec) at 19,690 ft (6000 m) - 315 ft/min (1.6m /sec) at 36,090 ft (11000 m).

Range: 410 miles (660 km) at 35,990 ft (10970 m).

Weight: Empty 4,520 lbs (2050 kg) with a maximum take-off weight of 5,941 lbs (2695 kg).

Dimensions: Span 23 ft 7 1/2 in (7.20 m); length 29 ft 8 1/4 in (9.05 m); height 8 ft 7 1/2 in (2.55 m); wing area 120.56 sq ft (11.20 sq m).

Armament: (Early) Two 30 mm Rheinmetall MK 108 cannon with 50 rounds per gun. (Late) Two 20 mm Mauser MG 151/20 cannons with 120 rounds per gun.

Variants: He 162A-0 (pre-production), He 162A-1, He 162A-2.

Avionics: FuG 24 R/T (radio) FuG 25a IFF.

History: First flight 6 December 1944; first delivery January 1945.

Operators: Germany (Luftwaffe).

 Source;www.century-of-flight.net,with necessary changes.

Messerschmitt ME 264 America

Me.264 AMERICA

The Messerschmitt Me 264 Amerika (America) was a long-range strategic bomber aircraft developed during WW2 for the Luftwaffe under the Reichsluftfahrtministerium's "Amerika Bomber" programme.

The bomber was to be capable of flying from Germany to New York City and back. One prototype was made but production was abandoned to allow Messerschmitt to concentrate on fighter production and because the Junkers Ju 390 had been selected in its place for the Amerika Bomber.

The Me 264 had little armour and guns in the interest of increasing fuel capacity. The heavy bomber would have had a crew of 5-6.

It had four 1,700 HP BMW 801D 14-cylinder radials with GM-1 (nitrous oxide-laughing gas) boost on its 141 foot wings.  The smooth fuselage measured 68.5 feet in length and it could weigh as much as 123,460 lbs. when fully loaded.  75-79,000 lbs. was normal.  A 4,400 lb. bomb load could be carried at maximum range configuration.  Four 13 mm Mg 131s and two 20 mm MG 151s were mounted for defensive purposes.  Normal cruise was 217 MPH but at 75,000 lbs. it could haul at 351 MPH with the GM-1 on at its 27,230-foot ceiling.

Specifications

Year deployed Wing span, m Length, m Height, m Wings area, m2 Weight, kg empty aircraft maximum take-off Engine Power, hp Maximum speed, km/h Cruising speed, km/h Range, km Rate of climb, m/min Service ceiling, m Crew Armament:

1944 43.00 20.90 4.30 127.80 21150 56000 4 PE BMW 801D or G 4 У 1700 560 14900 120 - 8000 6-9 2 20-mm cannon MG 151 up to 2000 kg bombs

Messerschmitt ME 110

Messerschmitt Me 110

 

The Messerschmitt Bf 110 was an aircraft of mixed success. While a failure during the Battle of Britain as a fighter (for which it was initially designed as), it did enjoy success in other roles. Yet, this aircraft that did not match up to Luftwaffe expectations managed to serve Germany throughout the Second World War in long-range escort fighter, fighter-bomber, reconnaissance, ground attack and night fighter roles.

The long-range multi-seat escort fighter is possibly the most difficult of combat aircraft to design. Certainly no entirely successful machine in this category emerged from the Second World War, and when Professor Willy Messerschmitt began design studies for such a warplane towards the end of 1934 at the Bayerische Flugzeugwerke at Augsburg his problems would have seemed insurmountable had he possessed a full knowledge of interceptor fighter development trends abroad. Such a machine as was required by Marshal Goering to equip the elite "Zerstorer" formations that he envisaged had to be capable of penetrating deep into enemy territory, possessing sufficient range to accompany bomber formations. The fuel tankage necessary presented a serious weight penalty and called for the use of two engines if the "Zerstorer" was to achieve a performance approaching that of the lighter interceptor fighter by which it would be opposed. Yet it had to be manaoeuvrable if it was to successfully fend off the enemy's single seaters.

Messerschmitt possessed no previous experience with twin-engined military aircraft when he commenced work on the Bf 110. Indeed, his first warplane, the single seat Bf 109 , had been conceived only the previous summer. At the time, the most powerful aero engine of national design available was the Junkers Jumo 210A of 610 hp (455 kw). It was obvious from the outset that a pair of such engines would be inadequate to provide the power needed for the relatively large and heavy fighter envisaged. However, the Daimler-Benz Aktiengesellschaft was actively engaged in developing a new 12-cylinder liquid-cooled inverted-vee engine, the DB 600 , which held promise of 1,000 hp (746 kw) and on the premise that such engines would be available for his prototypes, Messerschmitt began the design of the Bf 110.

Designed to a 1934 requirement for a long range escort fighter, the first prototype Bf 110 made its initial flight on May 12, 1936. A key factor in the design was the use of two Daimler-Benz DB 600 engines; subsequent difficulty in obtaining enough of these to power development aircraft meant that the Bf 110 could not be tested during the Spanish Civil War. Nevertheless, one aircraft was tested at the Rechlin evaluation centre in 1937 and proved to be very fast, although not as manoeuvrable as hoped. Despite obvious shortcomings, the Bf 110 entered service in 1939 as the Bf 110C, powered by two 1100 hp (820 kw) DB 601A engines. Production was set up on a massive scale, and by the end of the year some 500 Bf 110s were flying operationally.

By the time Germany invaded Poland on September 1,1939, ten Luftwaffe Gruppen had been equipped with the heavy fighter. Owing to the limited aerial opposition the Bf 110C was largely employed in the ground-support role, and after the fall of Poland little was heard of this much-vaunted machine until, on December 14, 1939, it was encountered by a formation of twelve Wellingtons over the Heligoland Bight. But it was not until it was to come up against R.A.F. fighters in 1940 that the Bf 110C was to receive its first real trial in combat and to be found wanting.

As a long-range escort fighter the Bf 110C received a disastrous mauling at the hands of the more nimble Hurricane and Spitfire during the "Battle of Britain". Rather than protecting the bombers under escort, the Bf 110C formations usually found that they were hard put to defend themselves, and the farcical situation developed in which single-seat Bf 109E fighters were having to afford protection to the escort fighters. The complete failure of the Bf 110C in the role for which it had been conceived led to its eventual withdrawal from the Channel coast but did not result in any reduction in its production priority.

Against Polish PZL fighters and other European countries the aircraft fared well, but when used during the Battle of Britain to escort German bombers, Royal Air Force fighters dealt heavily with the aircraft, forcing the Luftwaffe to switch to short-range Bf 109s for escort duties. Although the Bf 110s had failed in this primary task, production continued at a high rate; by 1945 no fewer than 6,150 had been built, ranging from Bf 110As to Gs. As later models became available, the early Bf 110Cs and Ds were transferred to the Middle East and Eastern Front.

Both the "C" and "D" models had almost disappeared from the European theatre by the summer of 1941, although they were being used extensively on the Russian front and in the Middle East. Production during 1940 had risen to 1,083 machines, but with the impending introduction of the Me 210 only 784 machines were produced in the following year.

By the end of 1942, in which year 580 Bf 110s were produced, production of this aircraft had again been stepped up as, on April 17, production of the Me 210 was canceled after numerous accidents, thus leaving a serious gap in the Luftwaffe's fighter and fighter bomber production program. To fill the gap an improved version of the Bf 110 was introduced, the G-series with the DB 605 engine which provided 1,475 hp (1100 kw) for take-off and 1,355 hp (1011 kw) at 18,700 feet. The pre-production Bf 110G-0 fighter-bomber was delivered for service evaluation late in 1942, and from early in 1943 G-series machines were encountered in increasing numbers. Apart from its engines the first production model, the Bf 110G-1, was similar to earlier fighter-bomber variants, and the G-2 differed principally in the armament installed: two or four 20 mm. MG 151 cannon and four 7.92 mm. MG 17 in the nose plus two 7.92 mm. MG 81 in the rear cockpit.

The Bf 110Es were capable of carrying a respectable bomb load of 4,410 lbs (2000 kg) as fighter-bombers, while straight fighter and reconnaissance versions were also built. These, and later versions, were operated with a fair degree of success in many war zones. The Bf 110F was basically similar to the E, but two new variants were produced - the 110F-2 carrying rocket projectiles and the F-4 with two 30 mm cannon and an extra crew member for night fighting. The last version, the Bf 110G, was intended for use originally as a fighter-bomber but, in view of the success of the F-4 and the increasingly heavy attacks on Germany by Allied bombers, was employed mostly as a night fighter.

From time to time Bf 110G night fighters were used on day operations. They were first employed as close escort to the Scharnhorst and the Gneisenau off the Dutch coast and Heligoland Bight, and in the summer of 1943 they fought American day-bomber formations whenever the latter flew unescorted. The Bf 110G groups sustained heavy losses during these actions owing to their pilots, trained in night-fighting tactics, going in close before attacking and being met by the heavy defensive fire of the bombers. They were no match for American fighters escorting American B-17 and B-24 bombers over Berlin.

It was in a Bf 110 that Rudolf Hess, Deputy Fuhrer of Germany, flew solo to Scotland on the night of May 10, 1941 in the hope of negotiating peace terms with Britain, without Hitler's knowledge.

A Messerschmitt Bf 110G-4/R3 8th Staffel 3rd Nachtjagdgeschwader Belgium 1944

Specifications (Messerschmitt Bf 110G-4/R3)

Type: Two or Three Seat Night Fighter
Design: Willy Messerschmitt
Manufacturer: Bayerische Flugzeugwerke (after 1938 Messerschmitt AG)
Powerplant: Two 1,475 hp (1100 kw) Damlier-Benz DB 605B inverted V-12 piston engines.
Performance: Maximum speed 342 mph (550 km/h) at 22,900 ft (6980 m); cruising speed 317 mph (510 km/h) at 19,685 ft (6000 m); service ceiling 26,245 ft (6780 m); initial climb: to 18,045 ft (5500 m) in 8 minutes.
Range: 1,305 miles (2100 km) with two 66 Imperial Gallon drop tanks mounted under the wing outboard of the engines.
Fuel: (C-4/B) Fuel was provided in four tanks, located in the inner wings either side of the main spar. The forward tanks each held 373 litres (82 Imperial gallons), while the rear tanks each held 264 litres (58 Imperial gallons). Later versions could carry two drop tanks to increase range.
Weight: Empty 11,222 lbs (5090 kg) with a maximum take-off weight of 21,805 lbs (9890 kg).
Dimensions: Span 53 ft 3 3/4 in (16.25 m); length 42 ft 9 3/4 in (13.05 m); height 13 ft 8 1/2 in (4.18 m); wing area 413.35 sq ft (38.40 sq m).
Armament: Two 30 mm MK 108 cannon (135 rounds per gun) and two 20 mm MG 151 cannon (300 rounds (port) and 350 rounds (starboard)) in the nose, and two 20 mm MG 151 cannon in a trainable Schrage Musik mount in the rear cockpit. An option was the installation of a Waffenwanne 151Z ventral tray, housing two forward firing 20mm MG 151 cannon. Some aircraft had two 7.92 mm (0.31 in) MG 81 machine guns instead of the two 20 mm MG 151 in the rear cockpit. A small number of aircraft had provisions for 210 mm Wfr Gr 21 rockets under the wings. On models designated for fighter bomber service, ETC 50 racks were installed under the wings capable of carrying 2,645 lbs (1200 kg) of bombs.
Variants: Bf 110A-0 (three production aircraft), Bf 110B, Bf 110B-1/B-2/B-3 (initial production), Bf 110-C, Bf 110C-1 to Bf 110C-4, Bf 110C-4/B, Bf 110C-5 (reconnaissance), Bf 110C-6, Bf 110C-7 (fighter bomber), Bf 110D, Bf 110D-1/R-1 & Bf 110D-1/R-2 (long range escort fighters), Bf 110D-1/U-1 (night fighter), Bf 110D-2 (long range fighter bomber), Bf 110D-3 (convoy escort), Bf 110E (pre-production), Bf 110E-1 (production aircraft), Bf 110E-2 (fighter bomber), Bf 110E-3 (long range reconnaissance), Bf 110F (engine and armor upgrades), Bf 110F-0 to Bf 110F-1, Bf 110F-2 (converted to fire rockets but proved unsatisfactory), Bf 110F-3 to Bf 110F-4, Bf 110G, Bf 110G-0 to Bf 110G-4, Bf 110H, Bf 110G-0 to Bf 110G-4.
Avionics: FuG 10P R/T Set, FuB1 2F Airfield blind approach reciever, FuG 227/1 Flensburg Homing System (used to home in on British Monica tail warning radar emissions - only fitted to some aircraft), FuG 212 Lichtenstien C-1 Radar, FuG 220b Lichtenstien SN-2 Radar.
History: First flight (Bf 110V-1 prototype) 12 May 1936; (pre-production Bf 110C-0) February 1939; operational service with Bf 110C-1, April 1939; final run down of production (Bf 110H-2/H-4) February 1945.
Operators: Germany (Luftwaffe), Hungary, Italy, Romania.
Source:www.century-of-flight.net,with necessary changes. 

Torpedoes

The Torpedoes

Type

Propulsion

Range/Speed

G7a

T1

Compressed air (wet heater)

6000m/44kts 8000m/40kts 14000m/30kts

The pre-war issue torpedo, it had the disadvantage of leaving a visible trail of bubbles on the surface on its way to the target.

G7e

T2

Electric

5000m/30kts *

The standard torpedo of the war. It suffered from early problems with its internal depth-keeping equipment, and its firing pistol, but these were solved after the Norwegian Campaign.
In mid 1942 an improved version was introduced with an icreased battery capacity. The increased battery capacity increased the range 50%. The improved G7e was designated T3a. Range was 7500m at 30 knots (preheated state - 4500m at 28 knots).
* data for preheated state. Full effectiveness was obtained when the T2 was preheated electrically to 30 degrees Cent (86 F) before firing. Not preheated figures are 28 knots for 3000m.

T3

Electric

5000m/30kts

As for T2 but fitted with an influence fuse.

T4

Electric

7500m/20kts

Falke, the first homing torpedo, was fitted with a passive acoustic homing device. It was introduced in March, 1943 and used by U-603 (Oblt. Bertelsmann), U-758 (Kptlt. Manseck) and U-221 (Kptlt. Trojer) against convoys HX-229 and SC-122. Few were used as it was replace by the T5 which was faster, had a greater range and could be used with either magnetic or contact detonators.

G7s

T5

Electric

5700m/24kts

The Zaunköning (Wren) came into service during the autumn of 1943. Intended to be an escort-killer, it achieved some early minor success only to be countered by the allied Foxer noise-making decoy. It was scoring hits against escort and merchants to the end of the war though.
The weapon was designed to lock onto the loudest noise after a run of 400m from its launch. This often proved to be the U-boat itself and standard issue-orders were to dive immediately to depth of 60m after launch froma bow tube while a stern shot was to be followed by a complete silence in the boat. Two U-boats were almost certainly lost when hit by one of their own T5 torpedoes, U-972 in Dec 1943 and U-377 in Jan 1944.

T11

Electric

5700m/24kts

A modified T5, less affected by Foxer. Never used in battle conditions although late test results were promising.

Variants

All the German U-boat torpedoes were 53.3cm (21 inch) in diameter and had a warhead of 280kg (The T5 had 274kg). There were also two important pattern-running devices which could be applied to various torpedo types. These were FAT and LUT.
The FAT (Federapparat Torpedo) ran a wandering course with regular 180-degree turns, was useful against convoys, and was fitted to both G7a and G7e T3s. From the end of 1942 onwards it was manufactured at the rate of roughly 100 per month.
LUT was a more sophisticated version of the FAT, with more variable patterns, but was only used operationally towards the end of the war.
Source:www.uboat.net,with necessary changes

Magnetic Anomaly Detection

As early as 1917, alternatives to the detection of submarines by hydrophones were being studied. One such area for consideration was the use of magnetism. In 1918 the U.S experimentally tried a ship towed magnetic detection device. This device was found to have too limited a detection range and also suffered from the presence of the magnetic signature of the towing ship. For the time being, magnetic detection was abandoned as impractical.
With the outbreak of WW II, renewed interest occurred in alternative detection systems for anti-submarine warfare. For aircraft there was a pressing need to devise a means for them to be able to detect a submerged submarine. One of the devices that received renewed attention was the use of magnetic anomaly detection.
As early as 1941 magnetic detection devices (which measure changes in the Earth's magnetic field) had been developed in both Britain and the U.S. The first airborne use of these devices was in U.S. K type blimps. This was followed by much wider installation of MAD devices in ASW patrol aircraft. By 1943 most ASW aircraft were equipped with MAD.
Initially, the U.S. thought that MAD would be a primary means of detecting submerged submarines. In use MAD was found to be a system of limited usefulness. This was due to its very limited range and, its inability to distinguish between sources of magnetic variance. Frequently, wrecks or local magnetic disturbances were classified as submarines. This was particularly true earlier in the war before experience with the system had discovered its limitations.
By late war, MAD in combination with sonobuoys proved more useful. In combination, MAD allowed an aircraft to localize a contact made with sonobuoys and, the sonobuoys provided confirmation that the contact was, indeed, a submarine. In this combination MAD became the secondary system to the sonobuoy, the reverse of what was originally expected and it double the threat for a u-boat.
Source:www.uboat.net,with necessary changes.

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If we run a professional site, and do not use graphics / pictures are fun, so do not expect people will want to linger on our website. People have come to seek information. Not to click on an ad or have their brain scrambled. Make your website a pleasant environment for visitors to enjoy. Think about when you go to the mall. We want to get a clean shop, which is prepared, have a great customer service and product that is being sought. Your website should reflect this. If there is what we expect in it like the shopping experience, visitors will enjoy what they are looking for on our website.
3. Color
Color is an individual choice, but studies show that color has an influence on the public's emotions. If we have a financial investment location, choose a conservative color. Or if we sell the material the beach, then choose soft colors.
4. About Us
People usually want to know basic things before they do business with us. Who we are, how they get a hold of us, what our product guarantee or warranty, when they will get the product, and others. We must answer these questions to create trust between us and potential customers.
5.Sitemap
Suppose we have a lot of resources and pages or products. A sitemap helps visitors to find what they're looking for quickly without having to search the entire site. This is especially useful for large sites, because it helps search engines to know what you are about very quickly.
6. Rapid loading
Nothing worse than a slow loading web pages. We can optimize your graphics for the website. People hate to wait. You can check the load time of pages and pages belonging to the Alexa.Com. Slow pages equal death to an online business.
7. Shopping Cart
If you are selling items or services, we need something that can be organized well and can trusted.We see some websites have a lot of products to register and email for reservations. What a nightmare! Yes, shopping carts will charge you a fee, but it is worth it to handle the transaction. There are many shopping carts available and we will research them based on business needs.
8.Templates or Original Design
People often think that to have a website designed is going to cost thousands. So they opt for the templates and arrange the location. There is nothing wrong with this approach except I can tell the difference between what I call "canned" site and that was created from scratch. While I do not think a website that uses templates will reduce the visitors, we think may not be appealing.
 9.Customer Service
Ok,and therefore how the customer service of a website designed? well, customer service should be writing our location. From the tips, free reports, collateral, to speed up and shop . People want to know a lot about what we are talking about and send their goods and guaranteed we will get ten times that.

ASDIC

ASDIC / Sonar

ASDIC, developed through the work of the Anti-submarine Detection Investigation Committee , from which its name is derived, was the primary underwater detection device used by Allied escorts throughout the war.
The first versions, crude to say the least, were created near the end of World War One and further developed in the following years by the Royal Navy.

How it works

The ASDIC, known to the Americans as Sonar, was basically a transmitter-receiver sending out a highly directional sound wave through the water. If the sound wave struck a submerged object it was reflected back and picked up by the receiver. The length of the time from transmission until the echo was received was used to measure the range, which was shown as a flickering light on the range scale. By mounting the transmitter head so that it could be directed almost like a searchlight, the bearing of the target could be read from the compass receiver.
The transmitter (sound) head extended beneath the ship, and was encased in a large metal done to minimize the noise of the water rushing past the ship while at moderate speed. This dome was filled with water, through which the sound passed, although this water was stationary and acted almost like a bumper. Noise level remained relatively low at moderate speeds, but anything above 18 knots resulted in too much noise and good contacts were difficult to find. The same results also resulted from bad weather when the ships were rolling, pitching and heaving.

The search pattern

During screening operations the ASDIC operator searched through an arc of roughly 45 degrees each side of the base course of the vessel. The ASDIC had to be stopped at regular intervals on this arc long enough to allow the relatively slow underwater sound waves to return should they locate a submerged target. Normally the head would be stopped on a bearing and a sound pulse would be transmitted, which would be heard as a "ping" noise. If no echo was received after several seconds the head would be rotated a few degrees (usually 5) and the process repeated throughout the watch.
If the outgoing impulse stuck a submerged target the echo would be heard as a distinct "beep". If this occurred the ASDIC operator would sound the alarm, feed the range and bearing to the bridge and then immediately start left and right cuts to try to determine the width of the target and trying to see if it was moving from one side to another. He could also determine if the target was closing or opening the range.
Echoes would bounce back from many things besides the U-boats such as whales, schools of fish, vertical sea currents and ship's wakes. This caused many false alarms, especially with the inexperienced operators. The veteran operator was much better at figuring out these bad signals and hunting down the intended target. The commanding officers quickly learned which operators were reliable.
Another problem was that often a real U-boat could not be detected due to water conditions. ASDIC was not very reliable in rough water, nor when layers of different temperature deflected the sound waves. U-boats could dive beneath such layers to avoid detection. Modern submarines use this tactic to this day.

ASDIC in a passive role

The device could also be used to listen as well as pinging. The propeller noises of the U-boat would sometimes be heard as well as its operation of various machinery and its use of compressed air in the ballast tanks to change depths. This was not very usual as one of the standard German tactics, when located, was to dive deep, rig for silent running and hide beneath a thermal layer at speeds slow enough to eliminate any cavitation from the propellers.

The attack

When the U-boat was located the attacking vessel would rush directly towards contact, usually at the speed of 15 knots. This run was used to determine the final movements of the target and further plot the final attack. The attacking vessel had to very sure where the boat was and estimate where it would be when the depth charges (or Hedgehogs) would reach its depth. Thus the attacking vessel would have to take a lead on the U-boat much as a hunter does on a bird. At 500 yards the allied commander hoped to know what the U-boat was doing and then he finalized his attack.
As the range closed the U-boat would pass under the beam of the ASDIC and be lost to the escort. The deeper the U-boat was the longer the range of the lost contact and thus more difficult to attack accurately. Normally a good and firm contact was lost at 300 yards. This did not affect the forward-throwing Hedgehogs as much as the depth charges.
Even if the attack was delivered with the correct lead angle and firing time there was no guarantee of damage to the U-boat since its depth could differ from the settings at which the depth charges were set to explode. The correct depth of the U-boat could only be guessed or estimated based on the range at which contact was lost.

U-boat's evasive maneuvers

The U-boats of course used tactics to evade the depth charges and Hedgehogs. The best time to act was when the attacking vessel had taken its lead angle and the ASDIC contact was just lost.
A very common German move was to run away from the escort and force it on a stern chase pinging through the wake of the U-boat which could give the ASDIC a hard time. Then at the moment of the ASDIC loosing contact the U-boat took a radical turn to left or right and more often than nor escaped out of the attacking pattern.
Another one was to turn radically with great power and disturb the water in order to confuse the ASDIC sometimes causing the attacker to be shaken off. The Germans also often released chemical pellets, which would produce clouds of bubbles to reflect the sound waves of the ASDIC.
Yet another tactic was to dive very deep and under a thermal layer or beneath the depth at which depth charges were normally set to explode. From 1942 onwards depths of 200 meters (600 feet) were not uncommon in an evasive tactic.

Source : www.uboat.net ,with necessary change.

The Deck guns

        
               The 88mm deck gun of Type VIIC boat U-486 seen in front of the tower.

The German U-boats of types I, VII, IX and X had a very powerful secondary weapon which was the deck gun. Each boat had one in front of the conning tower and with a good crew they could fire 15-18 rounds a minute. Often used to finish off damaged vessels or sink smaller ships the gun normally had a crew of 3 to 5 and was usually commanded by the second watch officer (IIWO).

                         
                                                Close-up of the 88mm deck gun.

In order to use the weapon the U-boat had to be on the surface naturally and it was normally not used when aircraft were suspected to be around. It required a line of men (3 which on the deck) to transport the ammunition from the main locker below the control room to the gun. The used rounds were taken back into the boat. The U-boats had a small water-proof ammunition locker for the gun on the deck in order to be able to start firing almost immediately when the order was given.
The smaller Type II coastal U-boats had no deck gun.
In 1937 plans were drawn up for type XI U-boat cruisers. Those huge boats would have had 4 pieces of 12,7cm guns in two separate towers. They were not built (see our "U-boat projects and proposals" page).

The 8,8cm gun

The type VII U-boats had the 8,8cm gun. This weapon is not to be confused with the famous German Army 8,8 anti-tank / anti-aircraft gun which was probably the best weapon of the war, they did not even use the same ammunition. The 8,8cm gun fired a 12-14 kilogram round (9kg warhead), on board were usually 250 rounds. From June 1943 the Atlantic-boats left their bases without the deck gun. Only in the Mediterranean and the Northern Sea boats kept their guns for a few months longer. In July 1944 some of the VIIC boats from the 8th Flotilla in Königsberg got their guns back for the patrols in the Baltic Sea against the Russians.
The 88mm naval deck gun was not capable of anti-aircraft fire since its maximum elevation was only 30 degrees.

The 10,5cm gun

The much wider deck of the larger I, IX, and X U-boats could accomidate the much more powerful 10,5cm/45 gun than 8,8 cm /45 on the narrow deck of the VII boats. These larger boats normally had 110 rounds of ammunition, although the IXD variant had 150 rounds, and one boat, the U-196, had 240 rounds.

The crew of U-124 during a drill.

Examples of use

Few commanders used the deck gun with better results than Reinhard Hardegen of U-123 did on his first 2 missions off the American coast in early 1942. His boat was of type IXB and thus had the larger 10,5cm version of the gun.

U-123 during a deck gun attack, note the merchant ship ahead.

The crews had some problems using the guns. There were several instances of barrel detonations, which killed or wounded some crew members. Often the reason was that the gun crew forgot to take away the muzzle protector from the gun - resulting in cartoon like blown up barrel if the gun gun was fired like that.
Sometimes the gun was used to shell shore-based targets like in the Caribbean where they fired at various installations like oil storage's and alike or in the Northern Sea where they damaged some radio stations. An excellent hit was landed by U-242 on 10 Oct, 1944 when it shot down a Russian aircraft with her 8,8cm deck gun!
19 Apr, 1942 In the Caribbean Sea U-130, under Korvkpt. Ernst Kals, successfully bombarded the oil refinery and storage on Curacao with his 105mm deck gun.
18 Sept, 1943 In the Northern Sea U-711, under Kptlt. Hans-Günther Lange, destroyed with the 8,8cm gun the Russian radio station "Pravdyi" near by the town Indiga, approx. 68.00N, 49.00E.
24 Sep, 1943 U-711 destroyed a few days later the Russian radio station "Blagopolncija" on the east of the island of Waigatsch, approx. 70.00N, 60.00E.

The end of the deck guns

After the massive anti-submarine build-up by the allies in 1942 and 1943 the deck guns were removed from almost all the boats in 1943 and 1944. A few commanders were allowed to retain them though, esp. the ones who commanded the boats in the Indian Ocean (the Monsun boats). But, in effect, from 1943 the deck gun was, for most boats, a thing of the past.

Source : www.uboat.net ,with necessary change.

The Electroboats

The Origins and Development of The Wonder U-boat

                               
                                       Type XXI Elektro boats after the surrender.

In the very last moments of the Second World War new U-boats, based on a completely new concept, saw action. Had they arrived earlier, they might have changed the outcome of the Battle of the Atlantic and more. The concept itself inspired the submarine design for the next two decades. Even more, the hull design of one of the Electroboats was adopted and used in the development of the world first nuclear submarine.

1. Origins

The development of the German U-boat fleet in 1935-39 was based entirely on the First World War principles. However, it had already been known that England was in possession of the underwater location device ASDIC(Anti Submarine Detection Investigate Comitee) which was to counter the submarine threat. Not surprisingly, the Second World War started with great speculations about the effectiveness of the U-boats.
Soon it had become apparent, that ASDIC was not so effective as claimed and certainly it was of no use against a surfaced U-boat. And it was a surfaced group attack at night, known as Rudeltaktik, that proved itself so lethal to convoys. Without a surface location device the escorts were not able to see a narrow silhouette of the surfaced U-boat at night or in bad weather. The same applied to aircraft.
The U-boat training programme was adopted to the principle of Rudeltaktik. The emphasis was on the skills of the commander and crew as it was believed that the experience was the main decisive factor in the battle.
The technical development was somewhat left behind. Doenitz got acquainted with Professor Walter and was quite impressed with the idea of a closed circle engine. Such an engine required no air intake and therefore could run when a submarine was submerged and at the same offered enough power to achieve speed around 25 knots. The idea was further developed and in 1940 the prototype V80 indeed travelled submerged at the speed of 26 knots! Therefore, the concept was regarded as the right answer for the need of high underwater speed. The amount of technical difficulties made it clear that it would take a long time to convert the prototype into an ocean-going attack U-boat. At that time, however, no one seemed to be worried as the conventional U-boats still enjoyed a high rate of success when operating on the surface at night.
However, there were early warnings that this situation might change dramatically. On the pitch black night 30th November - 1st December 1941 while attempting to penetrate the Straits of Gibraltar, U-96 was accurately located and bombed by the radar-equipped Sqdn. 812 Swordfish. Her commander, Heinrich Lehmann-Willenbrock, insisted that the aircraft must have been using a new location device. In spite of the fact this statement was made by one of the most experienced U-boat commanders, no one believed it was the case. In particular, no one believed an accurate radar set can be so small, it could fit in an aircraft.
Another warning came also in December 1941. It was the convoy battle around HG-76. The convoy was protected by an aggressive support group including an aircraft carrier,  lead by an ASW expert, Capt. Walker. Although a total of 14 U-boats were assembled in the area, only 5 ships were sunk at a cost of 4 U-boats directly involved in the operation (U-131, U-434, U-574 and U-567). A shocking exchange rate which later became normal. In fact a few more were sunk in the area at the same time. U-567 was commanded by Engelbert Endrass, an experienced Knight Cross Holder, while other boats by relatively inexperienced commanders. BdU was convinced that the success was entirely depending on the experience of attacking U-boats. This is why when Doenitz was sending Endrass, in whom he had great confidence, he had also signalled: "Hold on to that convoy. I'm sending Endrass". In vain.
There were a few more warnings. It was clearly demonstrated that with the arrival of the radar-equipped aircraft and escorts, especially when put together in a support group with a carrier, the conventional U-boats may achieve nothing but heavy losses. Unfortunately for the Germans, these warnings were not taken into consideration serious enough to affect the development plans for new U-boats, their weapons and electronic equipment. It was almost a year later, when the loses in the North Atlantic convoy battles became alarmingly high, when something finally happened.
November 1942 was the best month in the in terms of tonnage sunk during the U-boat War. The majority of sinkings happened along the North Atlantic convoy routes, in the so-called Atlantic Gap, out of the reach of land-based Allied aircraft. U-boats returned to the North Atlantic in the second half of 1942, when gradually stronger US anti-submarine forces made operations in the Western Atlantic and the Caribbean impossible. However, the British had enough time to increase the number of escorts, aircraft and develop new techniques. The Germans also increased the number of U-boats and in the second half of 1942 on average a hundred were at sea every day. All these factors inevitably lead to fierce convoy battles of previously unknown proportions.

2. Development

The scope of the November 1942 meeting was to examine the progress of the Walter U-boat which was the only possible solution to the situation that developed in the North Atlantic. Although the Walter concept and the first prototype V80 initially demonstrated remarkable performance, it had also delivered a whole range of new technical problems. These were particularly related to fuel required by the closed circle Walter engine - highly flammable Perhydrol. Due to the high rate of Perhydrol consumption a combat Walter U-boat would require a massive fuel tank, otherwise the underwater performance would not be satisfactory. The existing hull designs could not offer adequate fuel bunkerage. Therefore, Professor Walter presented a new double-hull design, forming a figure 8 in section. The upper part accommodated the crew, engines and torpedoes. The lower part used entirely as a fuel tank. The design was later known as Type XVIII.
However, it became clear that in spite of the advanced planning, the new Walter U-boat was not going to be operational in any foreseeable future. Moreover, any prospect on the Walter project would require a diversion of the shipyard resources from Type VII and IX building, which was at that time out of question. Therefore, it was decided to carry on the Walter projects but still on a limited research scale.
The meeting would end up in disappointment if it was not 2 engineers, Schuerer and Broecking, who realized a very simple solution, utilizing the new Walter hull design. Instead of using the lower section for Perhydrol, the idea was to install additional batteries there. This would effectively triple the battery capacity of the boat. Initial calculations showed that the performance of the new concept is far better than of the conventional U-boat, although not as good as of the Walter one. This however fully satisfied Doenitz and the development went ahead. The only problem was that the displacement of the boat was around 1600 tons - and at that time smaller boats around 1000 tons were preferred as much easier too handle and more resistant to depth-charges.
By the end of January 1943 detailed theoretical calculations were finished and by the end of June 1943 a preliminary design was completed. The following are the the most important features of the Type XXI design:

• Displacement of 1620 tons
• Streamlined hull with 6 forward torpedo tubes
• Full submerged speed of 18 knots for 1.5 hours
• Submerged speed of 12-14 knots for 10 hours
• Silent submerged speed of 5 knots for 60 hours
• Water-pressure controlled depth keeping equipment
• Semi-automatic hydrolic torpedo reload system
• New improved underwater listening device
• Sonar
• Radar-search receivers (to detect enemy radar)
• Radar
• Deep freezer
• No deck gun
• No external torpedo storage containers
• Schnorkel

The Type XXI design was presented to Hitler at a conference on the 8th July 1943 in order to obtain his approval for additional demands on the industry. The approval was given and on 13th August 1943 an order was given for the transition to building Electroboats. At the same time the building programme of the conventional boats was to be carried on, in order to make up for the expected losses till the arrival of new boats. The development of Walter boat was to continue, and in addition to 4 prototypes being built and order for additional 24 Type XVIIB and 2 Type XVIII boats was given.
Together with the development of Type XXI work had started on a small Electroboat for coastal operation. The large Electroboat was initially supposed to replace Type IX boats but after the May 1943 disaster it was obvious that it should also replace Type VII convoy attack boat. However, because of the size, Type XXI boat was not suitable for shallow water operations, particularly the North Sea, Black Sea and the Mediterranean. Therefore, a small Electroboat was proposed with the following features:

• displacement of 234 tons
• streamlined hull with 2 forward torpedo tubes (torpedoes in the tubes, no reloads)
• full submerged speed of 12 knots
• new improved underwater listening device
• easy to control
• Schnorkel

The plans for the small Electroboat, Type XXIII, were presented together with Type XXI and got approved.
Author could not positively established wether the Schnorkel was the inherent part of the Electroboat design from the very beginning or was added later, after experience was gained from the heavy losses in the first part of 1943. Certainly, Schnorkel was studied and added to the Walter U-boat concept at about that time. However, whenever the Schnorkel was considered, the final design of both Electroboats were equipped with the most modern telescopic device and were able to use it at much greater speeds than conventional Schnorkel U-boats.
A detailed production plan was worked out between July and December 1943.
At least 18 months were required to build a Type XXI U-boat under a conventional construction procedure (with boats built from start to finish on a single slip). This effectively meant that prototypes would be ready only in November 1944 and regular production boats would be ready for operational use in 1946. This was not acceptable.
Therefore the Minister for Armaments, Albert Speer, decided to consult the matter with Otto Merker, with experience in the mass production gained in the car industry. Eventually, an alternative production method was proposed with the following assumption:

• no prototypes
• pre-fabricated sections manufactured in parallel, in distributed works around the country
• sections to be transported to the shipyard by water (big Type XXI sections) or rail (smaller Type XXIII sections)
• final assembly of sections at the shipyard

The detailed building plan for the Type XXI consisted of the following stages:

acquisition of raw materials and transport to steel works	16 days
steel work	40 days
transport to the section building plant	5 days
section building	50 days
transport to the yard	4 days
assembly at the yard	50 days
final work after launching	6 days
total building time per boat	171 days (6 months)

The method eliminated the bottleneck caused by the limited shipyard resources. Instead of occupying a slip for the entire building process (18 months mentioned) it was required only for approximately 80 days of final completion (as it turned out to be). Hence the shipyard building effectiveness was multiplied by almost 7.
The following are the detailed descriptions of Type XXI and XXIII sections.

Type XXI section description

Section	description	weight (tons)	length (meters)
1	Stern with stern compartment	65	12.7
2	Electric motor room	130	10
3	Diesel engine room	140	8.4
4	Aft living quarters	70	5.3
5	Control room and galley	140	7.6
6	Forward living quarters	165	12
7	Torpedo stowage room	92	6.8
8	Bows with torpedo tubes	110	14
9	Conning tower superstructure		14.1

Type XXIII section description

Section	description	weight (tons)	length (meters)
1	Stern, steering installation, silent speed motor, gearing	11.5	9.2
2	Main engines and motors	14	6
3	Control room, forward living quarters (part)	18	7.5
4	Bows with torpedo tubes, forward living quarters (part)	16.25	10

On 30 September 1943 the building of some already obsolete boats was stopped (selected boats were already stopped on the 10th July). Subsequently, these boats were cancelled on the 6th November 1943 (the majority) or later (some particular boats). This applied to all Type VII C/42 boats and selected Type VII C/41, IX C/40, IX D/42, XVII B and XVII G boats.
Also, on the 6th November 1943 a final order for the construction of Type XXI boats was submitted to the following 3 shipyards:

Blohm & Voss, Hamburg	130 U-boats (U-2501 onwards)
Deschimag AG Weser, Bremen	87 U-boats (U-3001 onwards)
Schichau, Danzig (Gdansk)	70 U-boats (U-3501 onwards)

An order for the construction of Type XXIII boats was submitted slightly earlier, on 20th September 1943 to Deutsche Werft AG, Hamburg (U-2321 onwards) and later on 7th July 1944 to Germaniawerft, Kiel (U-2332-3, U-4701 onwards).
It is interesting to note that there had been some preliminary orders for Type submitted earlier, to other shipyards (e.g. order dated 6th July 1943 to Deutsche Werft AG for 24 Type XXI boats, cancelled on 30th September 1943).
From February 1944 onwards separate sections became systematically available. The first Electroboat to be laid down was a Type XXIII boat U-2321 on 10th March 1944. She was launched on the 17th April (after 38 days in the yard) and commissioned on 12th June 1944. The first Type XXI boat to be laid down was U-2501on 3rd April 1944. She was launched on 12th May 1944 (well ahead of the schedule) and commissioned on 27th June 1944.
The commission progress of Type XXI and XXIII boats is presented below:

Electroboat commission progress

Time	Type XXI	Type XXIII
June 1944	1	1
July 1944	3	3
August 1944	7	4
September 1944	8	6
October 1944	12	4
November 1944	13	7
December 1944	20	6
January 1945	22	12
February 1945	11	7
March 1945	18	6
April 1945	4	4
May 1945	-	1
Total	119	61

Type XXI commission progress

Time	Blohm&Voss	AG Weser	Schichau	Total
June 1944	1		-	1
July 1944	1	1	1	3
August 1944	3	3	1	7
September 1944	5	1	2	8
October 1944	6	3	3	12
November 1944	6	3	4	13
December 1944	6	6	8	20
January 1945	5	11	6	22
February 1945	5	6	-	11
March 1945	6	7	5	18
April 1945	4			4
May 1945				-
Total	48	41	30	119

Type XXIII commission progress

Time	Deutsche Werft AG	Germaniawerft	Total
June 1944	1	-	1
July 1944	3	-	3
August 1944	4	-	4
September 1944	6	-	6
October 1944	4	-	4
November 1944	6	1	7
December 1944	5	1	6
January 1945	9	3	12
February 1945	4	3	7
March 1945	3	3	6
April 1945	3	1	4
May 1945	-	1	1
Total	48	13	61

It is interesting to compare the technical data of both types of Electroboat and The Type XVIIB Walter U-boat:

	Type XXI	Type XXIII	Type XVIIB
Displacement surfaced (tons)	1621	232	312
Displacement submerged	1819	256	345
Dimensions (meters) - length	76.7	34.1	40.9
beam	6.6	3.0	3.4
draught	6.3	3.7	4.7
Machinery	2-shaft 6-cylinder MAN diesel/electric motors 4500/5000 bhp/shp silent speed electric motors 226 shp	1-shaft 6-cylinder MWM diesel 576 bhp AEG main electric motor 580 shp BBC silent speed electric motor 35 shp	Walter single-shaft turbines 2500 shp 8-cylinder Deutz diesel motor 210 bhp electric motor 77 shp
Fuel Capacity (tons)	250	18	75 (Perhydrol)
Batteries		62 double-cell 2x21MAL 740 E/23 5400Ah	4560 Ah
Maximum speed (knots) - surfaced	15.5	10.0	8.5
submerged	17.0	12.5	21.5 Walter 4.5 electric
max schnorkel speed		10.75
max silent speed		4.5
Endurance (miles) - max surfaced	15,500 @ 10 knots	4,450 @ 6 knots
surfaced	11,500 @ 12 knots	2,600 @ 8 knots	3,000 @ 8 knots
max sustained surfaced	5,100 @ 15.5 knots	1,350 @ 10 knots
max schnorkel endurance		3100 @ 6 knots
Endurance (miles) - max submerged	365 @ 5 knots	194 @ 4 knots
submerged	110 @ 10 knots	43 @ 10 knots	150 @ 20 knots
max sustained submerged		21 @ 12 knots	40 @ 4.5 knots electric
Diving depth - safe
Diving depth - max
Armament	6 bow tubes 23 torpedoes 2 twin 20 cm AA (3cm on later models)	2 bow tubes 2 torpedoes no guns	2 bow tubes 4 torpedoes no guns
Crew	57	14	19

It is important to remember that although the Walter U-boat possessed greater maximum speed and range, it was only of single use. Once the Perhydrol fuel was burn out, the boat could only bank on the conventional diesel-electric propulsion. The Electroboats could always recharge the batteries and therefore could benefit from the high underwater speed many times. On the other hand, the maximum speed was needed only for an attack - and with just 2 torpedoes the Walter U-boat indeed could practically attack only once. But having an ability to sprint away in the event of danger is always an advantage in the submarine warfare and therefore the Electroboats offered steady safety in comparison to the Walter ones.

3. Getting ready

The initial trials with the first available Type XXIs showed that the theoretical performance was almost met. The full submerged speed was slightly lower (17 instead of 18 knots) and could be maintained for a shorter time (60-80 minutes instead of 100). Overall, the performance was outstanding and offered much better prospects for attacking convoys and evading escorts than conventional U-boats.
At the silent submerged cruising speed the Type XXI had to schnorkel for only 3 hours a day to keep the batteries charged. This speed of 5 knots with a range of 365 miles meant that a U-boat would pass the dangerous waters between Norway and Iceland in 5 days schnorkeling shortly only 5 times. The radar-search receiver Tunis fitted to schnorkel and anti-radar rubber coating offered additional safety. Even when located, an alteration of speed and course would help to evade escorts or aircraft-dropped sonar buoys. When escaping at high speed, the Type XXI was almost as fast as most of the Allied escorts and bubbling of water rushing along the hull would make ASDIC location difficult. The potential area where a hunted Type XXI, escaping at the silent speed of 5 knots, would be forced to raise the schnorkel again was some 10-13 times greater than an area for conventional U-boat (escaping at 2 knots with a range of 100 miles). With the existing anti-submarine forces search abilities a chance for a kill was therefore greatly reduced.
The attack tactics was based on the following principles:

• location of a convoy by the listening device
• high-speed approach to the convoy
• penetration of the escort screen at silent speed and maximum depth
• getting underneath the convoy
• collecting firing data for the LUT looping torpedoes by echo-ranging
• firing spreads of torpedoes in order to cover the whole convoy

Special equipment was provided to facilitate the tactics, in particular a special echo-ranging plotting-table and an echo-ranging data converter which automatically calculated and set torpedo firing parameters. Due to the quick reload mechanism the Type XXI would need only one convoy encounter to fire all the torpedoes.
The preparation of the battle instructions for Electroboats was an interactive process with constant feedback and verification coming from the training units. The final battle instructions were written by experienced commanders: Erich Topp (for the Type XXI) and Carl Emmermann (for the Type XXIII). Others contributed though, among them Emil Klusmeier who later volunteered for a command in order to verify his ideas in practice and with U-2336 scored hits.
Although the first Type XXI was launched almost on time, the Electroboat building programme was eventually delayed by various means and the planned production figures had not been met. The following is the summary and status at the end of the war:

	Type XXI	Type XXIII
Planned for delivery by 1/05/45	381	95
Not produced because of the internal organization defects	202	13
Not produced because of Allied bombing on shipyards	60	19
Commissioned	119	61
Destroyed after commission  (trials, training, transit)	20	2
Training, fitting-out or on trials	86	38
Almost ready for combat	12	15
Fully ready for combat	1	6

The failure to achieve the objectives was mainly caused by organization troubles, faulty design and bad workmanship. It was particularly annoying, when sections did not fit to each other because the specified tolerances were exceeded. All these took place mainly in the first half of 1944 and was fixed in the second half of the year. At that time, however, the Allies realized the danger and started regular bombing raids, particularly on shipyards and water transport installations (needed for transportation of massive Type XXI sections).

Training for the new boats

Further delay in the project was caused by the extended training required for crews. The complexity of the design and new tactics meant that 6-7 months of training was required instead of usual 3-3.5 needed for conventional U-boats. Moreover, the training facilities were affected by the Allies actions, particularly the mining of the Bay of Danzig, the primary trial and training waters. The first mines were laid on 26/7 August 1944 by Bomber Command and continued regularly that eventually lead to the total abandoning of the area. The trials and tests were moved to the Bay of Luebeck which was much inferior, particularly because the area was within the range of Coastal Command.
The disruption of training caused that the Type XXI boats with practically one exception could not became fully operational in early 1945. Also, a number of boats that almost finished their training and awaited transfer to the Norwegian bases were lost in the dangerous Bay of Luebeck.

Operational Type XXI boats

The following Type XXI U-boats were almost ready for operations (on passage or in the operational bases, undergoing final preparations):

Place	Flotilla	Boat	Commander
in transit	11th Flotilla Bergen	U-2503 *	Oblt Raimund Tiesler
Bergen	11th Flotilla Bergen	U-2506	Kptlt Horst von Schroeter
Bergen	5th Flotilla Kiel	U-3514	Oblt Guenther Fritze
Stavanger	4th Flotilla Sttetin	U-3035	Oblt Ernst-August Gerke
Kristiansand	31st Flotilla Hamburg	U-2529	Kptlt Fritz Kalipke
Horten	11th Flotilla Bergen	U-2502	Kptlt Heinz Franke
Horten	11th Flotilla Bergen	U-2513	Korvkpt Erich Topp
Horten	11th Flotilla Bergen	U-2518	Kptlt Friedrich Weidner
Horten	4th Flotilla Sttetin	U-3017	Oblt Rudolf Lindschau
Horten	4th Flotilla Sttetin	U-3041	Kptlt Hans Hornkohl
Horten	5th Flotilla Kiel	U-3515	Oblt Fedor Kuscher
Wilhelmshaven	11th Flotilla Bergen	U-3008	Kptlt. Helmut Manseck

* U-2503 was badly damaged by aircraft on 3rd May 1945 and later scuttled.
The following was the only one Type XXI U-boat fully ready for operations at the end of the war:

Bergen

11th Flotilla Bergen

U-2511

Korvkpt Adalbert Schnee

It is sometimes reported that U-3008 also was ready for operations. She indeed sailed from Wilhelmshaven on 3rd May 1945, when the artillery bombardment was already heard. The U-boat may probably been supposed to call in one of the Norwegian ports for final provisioning before the patrol. In the North Sea, shortly after the order to surrender which was issued on 4th May 1945, she encountered a convoy, made a pass under it and sailed away undetected.

First war patrol by type XXI boat, the U-2511

U-2511, with a crack crew, sailed from Kiel on 16 March 1945 for the Norwegian base Horten in Norway. The war patrol was supposed to start on 26 March, but during deep dive test she sustained a periscope damage and was delayed. She sailed from Horten on the 18 April she was forced to put to Bergen on 21 April, due to diesel troubles. At last she sailed on 30 April 1945 with the orders to go to the Caribbean.
The first contact with the enemy was made on 1 May. On the following day U-2511 was detected by an escort group north of Scotland but easily got away with the increased underwater speed. She evaded other ships, too, as her objective was to get to the operation area first. Depth-charges were dropped but were helplessly wide. Soon after receiving the surrender message on 4 May 1945, U-2511 detected a Suffolk class cruiser, HMS Norfolk, with destroyer escort at a long range. She made a text-book approach, closing at high-speed first, then diving deep and passing the destroyer screen at silent-speed. Finally, Schnee had the cruiser in sights 500 meters away with a perfect attacking position inside the destroyer screen and undetected - impossible  to miss. U-2511 did not fire but dived deep again, and still undetected returned to base, arriving at Bergen on 5 May 1945.

4. Aftermath

What may be a sort of surprise is that the technology used in the design was by no means new. To characterize the concept, the following 3 features should be listed:

1. streamlined hull
2. snorchel
3. huge battery capacity

The benefits of the streamlined hull had been known long before the era of Electroboats. In fact, the very first submarines including original Holland's vessel were more streamlined than their WW1 and WW2 successors. Schnorchel was developed in the 30's by the Dutch, but the concept was known to the others. Adding more battery capacity is just a matter of space, not technology.
Therefore, it should be noted that the technology used for Electroboats was actually available already in the 30's. Why it was not exploited? There was no need to do so as long as the U-boat was safer and performed better on the surface at night than under the surface. This was clearly demonstrated in the first few years of the U-boat War. Only when the relative safety of staying on the surface was taken away by radar and aircraft, the German Naval High Command started looking for an alternative solution.
The reason for the late introduction of Electroboats should be primarily related to the underestimation of radar technology. In this particular field the Germans were significantly behind England. Had the German radar technology been more advanced, it would have probably been realized that it was just a matter of time before the small silhouette of the surfaced U-boat was indeed big enough for the radar to be located. And then the Electroboats could have come earlier.
Also, outstanding was the production process of the Electroboats, particularly the larger one. It was one of the few examples of the implementation of mass-production principle by the German industry during the Second World War. Of course, this too was affected by the Allied bombing, but the final number of commissioned Electroboats should be regarded as high. It is again a kind of surprise that the mass-production concept was not adopted earlier, particularly for the conventional U-boat production. A high number of conventional U-boats in the second half 1941, when the British counter-measures were not fully developed yet, instead of 1942, certainly would have made a difference.
The experience of U-2511 clearly demonstrates the outstanding performance of the Type XXI and  it is certain, that the Allied navies had no ready answer to the new threat. The operations of the Type XXIII constitute yet another proof of the fighting qualities of the Electroboats. Had the Allied progress on land been slower, the Type XXI U-boats might have appeared in numbers great enough to paralyze the Atlantic communication routes, even in spite of the increased bombing of production and training facilities.

Electro boat diary:

November 1942	The birth of the Electroboat idea
January 1943	Theoretical calculations finished
June 1943	Design completed
July 1943	Project approved
September 1943	Conventional U-boat building programme limited
November 1943	Orders placed
December 1943	Production design completed
30 April 1944	First Type XXIII launched (U-2321)
12 May 1944	First Type XXI launched (U-2501)
12 June 1944	First Type XXIII commissioned (U-2321)
27 June 1944	First Type XXI commissioned (U-2501)
August 1944	First aerial mines in the Bay of Danzig
29 January 1945	First Type XXIII sailed on war patrol (U-2324)
February 1945	Testing and training transferred to the Bay of Luebeck
14 February 1945	First success by an Electroboat (U-2322)
30 April 1945	First Type XXI sailed on war patrol (U-2511)
7 May 1945	Last success of an Electroboat and in the war (U-2336)

 Source : www.uboat.net ,with necessary change.