Graf Zeppelin-class aircraft carrier

Aircraft carrier Graf Zeppelin
Class overview
Planned	2
Cancelled	2
General characteristics
Displacement	33,550 tonnes
Length	262.5 m (861 ft 3 in)
Beam	31.5 m (103 ft 4 in)
Draft	7.6 m (24 ft 11 in)
Propulsion	Geared turbines, 200,000 hp (150,000 kW), four screws
Speed	35 kn (65 km/h)
Range	14,816 km (8,000 nmi) at 19 kn (35 km/h)
Complement	1,720 crew 306 flight personnel
Armament	16 × 15 cm SK C/28 guns 12 × Flak (10.5 cm) 22 × 3.7 cm SK C/30 (AA) 28 × Flak (2.0 cm)
Aircraft carried	Complement of 43 10 × Messerschmitt Bf 109 fighters 13 × Junkers Ju 87 dive bombers 20 × Fieseler Fi 167 torpedo bombers

The Graf Zeppelin-class aircraft carriers were two German Kriegsmarine aircraft carriers laid down in the mid-1930s as part of the Plan Z rearmament program. Four ships were initially envisioned but reduced to two by Großadmiral (Grand Admiral) Erich Raeder in 1939. Eventually, only the Graf Zeppelin was launched in 1938 but never completed; she was sunk as a target ship by the Soviets in 1947. Construction on the second ship, designated Flugzeugträger B, was halted in 1939, before launching; the ship was scrapped the following year.

A lack of experience in building aircraft carriers led to difficulties in implementing advanced technologies such as aircraft catapults into the Graf Zeppelin class. German designers studied Japanese designs but were constrained by the realities of creating a North Sea carrier versus a "Blue Water" design. For instance, several cruiser-type guns were envisioned to allow commerce raiding and defense against British cruisers. This contrasted with American and Japanese designs, which were more oriented toward a task-force defense and relied on supporting cruisers for surface firepower.

These ships were also the subject of intense political wrangling within the German military. Reichsmarschall Hermann Göring, Commander of the Luftwaffe, was resentful of any incursion on his authority as head of the country's air power and frustrated Raeder at every opportunity. Within his own service, Raeder found opposition in Admiral Karl Dönitz, a submariner. Führer und Reichskanzler (Leader and Reich Chancellor) Adolf Hitler showed a decreasing interest in the carriers and became disappointed with the Kriegsmarine's surface fleet after the Battle of the Barents Sea in December 1942. This disenchantment on Hitler's part led to a stop on completing Graf Zeppelin and the resignation of Raeder.

Planning and construction

Construction work in Kiel, 1938

Wilhelm Hadeler had been Assistant to the Professor of Naval Construction at the Technical University of Berlin for nine years when he was appointed to draft preliminary designs for an aircraft carrier in April 1934. The Anglo-German Naval Agreement signed 18 June 1935 allowed Germany to construct aircraft carriers with displacement up to 38,500 tons. In 1935, Adolf Hitler announced that Germany would construct aircraft carriers to strengthen the Kriegsmarine. A Luftwaffe officer, a naval officer and a constructor visited Japan in the autumn of 1935 to obtain flight deck equipment blueprints and inspect the Japanese aircraft carrier Akagi. The keel of Graf Zeppelin was laid down the next year. Two years later, Großadmiral (Grand Admiral) Erich Raeder presented an ambitious shipbuilding program called Plan Z, in which four carriers were to be built by 1945. In 1939, he revised the plan, reducing the number to two.

The Kriegsmarine has always maintained a policy of not assigning a name to a ship until it is launched. The first German carrier, laid down as "Flugzeugträger A" ("Aircraft carrier A"), was named Graf Zeppelin when launched in 1938. The second carrier — never launched — bore only the title "Flugzeugträger B", but might, if completed, have been called Peter Strasser.

Graf Zeppelin is launched, 8 December 1938

A review of Hitler's conferences on the German Navy, the minutes of which were captured after the fall of the Third Reich, reveals his decreasing interest in the carriers. Reichsmarschall Hermann Göring, Commander of the Luftwaffe, was resentful of any incursion on his authority as head of the country's air power, and he frustrated Raeder at every opportunity. Within his own service, Raeder found opposition in Admiral Karl Dönitz, a submariner.

Having no experience building such ships, the Kriegsmarine had difficulty implementing advanced technologies such as aircraft catapults into the Graf Zeppelin class. German designers were able to study Japanese designs, but were constrained by the realities of creating a North Sea carrier vs. a "Blue Water" design. Several cruiser-type guns were envisioned to allow commerce raiding and defense against British cruisers, for example. This is in contrast to American and Japanese designs, which were more oriented toward a task-force defense, using supporting cruisers for surface firepower.

Design

Hull

The Graf Zeppelin class's hull was divided into 19 watertight compartments, the standard division for all capital ships in the Kriegsmarine. Their belt armor was to vary from 100 mm (3.9 in) over the machinery spaces and aft magazines, to 60 mm (2.4 in) over the forward magazines and tapered down to 30 mm (1.2 in) at the bows. Stern armor was kept at 80 mm (3.1 in) to protect the steering gear. Inboard of the main armor belt was a 20 mm (0.79 in) anti-torpedo bulkhead.

Graf Zeppelin at Kiel, June 1940, displaying her newly rebuilt bow. Notice that the photo is marked Secret (Geheim).

Horizontal armor protection against aerial bombs and plunging shellfire started with the flight deck, which acted as the main strength deck. The armor was generally 20 mm (0.79 in) thick except for those areas around the elevator shafts and funnel uptakes where thickness increased to 40 mm (1.6 in) in order to give the elevators necessary structural strength and the critical uptakes greater splinter protection. Beneath the lower hangar was the main armored deck (or tween deck) where armor thickness varied from 60 mm (2.4 in) over the magazines to 40 mm (1.6 in) over the machinery spaces. Along the peripheries, it formed a 45 degree slope where it joined the lower portion of the waterline belt armor.

The Graf Zeppelins' original length-to-beam ratio was 9.26:1, resulting in a slender silhouette. However, in May 1942, the accumulating top-weight of recent design changes required the addition of deep bulges to either side of Graf Zeppelin's hull, decreasing that ratio to 8.33:1 and giving her the widest beam of any carrier designed prior to 1942. The bulges served mainly to improve Graf Zeppelin's stability but they also gave her an added degree of anti-torpedo protection and increased her operating range because selected compartments were designed to store approximately 1500 tons more fuel oil.

Graf Zeppelin's straight-stemmed prow was rebuilt in early 1940 with the addition of a more sharply angled "Atlantic prow", intended to improve overall seakeeping. This added 5.2 m (17 ft) to her overall length.

Machinery

The Graf Zeppelin class's power plant was to consist of 16 La Mont high-pressure boilers, similar to those used in the Admiral Hipper-class heavy cruisers. Their four sets of geared turbines, connected to four shafts, were expected to produce 200,000 shp (150,000 kW) and propel the carrier at a top speed of 35 knots (40 mph; 65 km/h). With a maximum bunkerage capacity of 5000 tons of fuel oil (prior to the addition of bulges in 1942), the Graf Zeppelins' calculated radius of action was 9,600 miles (15,400 km) at 19 knots (35 km/h; 22 mph), though wartime experience on ships with similar powerplants showed such estimates were highly inaccurate. Actual operational ranges tended to be much lower.

Two Voith-Schneider cycloidal propeller-rudders were to be installed in the forward bow of the ship along the center-line. These were intended to assist in berthing the ship in harbor and also in negotiating narrow waterways such as the Kiel Canal where, due to the carrier’s high freeboard and difficulty in maneuvering at speeds below 8 knots (15 km/h; 9.2 mph), gusting winds might push the ship into the canal sides. In an emergency, the units could have been used to steer the ships at speeds under 12 knots (22 km/h; 14 mph) and, if the ships' main engines were rendered inoperable, could propel the vessel at a speed of 4 knots (7.4 km/h; 4.6 mph) in calm seas. When not in use, they were to be retracted into their vertical shafts and protected by water-tight covers.

Flight Deck & Hangars

The Graf Zeppelins' steel flight deck, overlaid with wooden planking, was 242 m (794 ft) long by 30 m (98 ft) wide at its maximum. It had a slight round down right aft and overhung the main superstructure but not the stern; being supported by steel girders. At the bow, the carriers were to have an open forecastle and the leading edge of her flight deck was uneven (mainly due to the blunt ends of her catapult tracks), but it did not appear likely that would have caused any undue air turbulence. Careful wind-tunnel studies using models confirmed this. However, their long low island structure did generate a vortex over the flight deck in these tests when the ship yawed to port. This was considered to be an acceptable hazard when conducting air operations.

The Graf Zeppelin class's upper and lower hangars were long and narrow with unarmored sides and ends. Workshops, stores and crew quarters were located outboard of the hangars, a design feature similar to that of British carriers. The upper hangar measured 185 m (607 ft) x 16 m (52 ft); the lower hangar 172 m (564 ft) x 16 m (52 ft). The upper hangar had 6 m (20 ft) vertical clearance while the lower hangar had 0.3 m (1 ft 0 in) less headroom due to the ceiling braces. Total usable hangar space was 5,450 m² (58,700 sq ft) with stowage for 41 aircraft: 18 Fieseler Fi 167 torpedo-planes in the lower hangar; 13 Junkers Ju 87C dive-bombers and 10 Messerschmitt Bf 109T fighters in the upper hangar.

The Graf Zeppelin class had three electrically-operated elevators positioned along the flight-deck's center-line: one near the bow, abreast the forward end of the island; one amidships; and one aft. They were octagonal in shape, measuring 13 m (43 ft) x 14 m (46 ft), and were designed to transfer aircraft weighing up to 5.5 tons between decks.

Two Deutsche Werke compressed air-driven catapults were installed at the forward end of the flight deck for power-assisted launches. They were 23 m (75 ft) long and designed to accelerate a 2,500 kg (5,500 lb) fighter to a speed of approximately 140 km/h (87 mph) and a 5,000 kg (11,000 lb) bomber to 130 km/h (81 mph).

A dual set of rails led back from the catapults to the forward and midship elevators. In the hangars, aircraft would have been hoisted by crane onto collapsible launch trollies. The aircraft/trolley combination would then have been lifted to flight deck level on the elevator and trundled forward to the catapult start points. As each plane lifted off, its launch trolley would have been caught in a metal "basket" at the end of the catapult track, lowered to the forecastle on "B" deck and rolled back into the upper hangar for re-use via a secondary set of rails. When not in use, the catapult tracks were to be covered with sheet metal farings to protect them from harsh weather.

Eighteen aircraft could have theoretically been launched at a rate of one every 30 seconds before exhausting the catapult air reservoirs. It would then have taken 50 minutes to recharge the reservoirs. The two large cylinders holding the compressed air were housed in insulated compartments located between the two catapult tracks, below flight deck level but above the main armored deck. This positioning afforded them only light protection from potential battle damage. The insulated compartments were to be electrically heated to a temperature of 20 °C (68 °F) in order to prevent ice from forming on the cylinder piping and control equipment as the compressed air was vented during launches.

It was intended from the outset that all of the Graf Zeppelins' aircraft would normally launch via catapult. Rolling take-offs would be performed only in an emergency or if the catapults were inoperable due to battle damage or mechanical failure. Whether this practice would have been strictly adhered to or later modified, based on actual air trials and combat experience, is open to question, especially given the limited capacity of the air reservoirs and the long recharging times necessary between launches. One advantage of the system, however, was that it would have allowed Graf Zeppelin to launch and land aircraft simultaneously.

To facilitate rapid catapult launches and eliminate the necessity of time-consuming engine warm-ups, up to eight aircraft were to be kept in readiness in the hangar by the use of steam pre-heaters. These would keep the aircraft engines at an operational temperature of 70 °C (158 °F). In addition, engine oil was to be kept warmed in separate holding tanks, then added via hand-pumps to the aircraft engines shortly before launch. Once the aircraft were raised to flight deck level via the elevators, aircraft oil temperature could be maintained, if need be, through the use of electric pre-heaters plugged into power points on the flight deck. Otherwise the aircraft could have been immediately catapult-launched as their engines would already have been at or near normal operating temperature.

Four arrester wires were positioned at the after end of the flight deck with two more emergency wires located afore and abaft of the amidships elevator. Original drawings show four additional wires fore and aft of the forward lift, possibly intended to allow recovery of aircraft over the bows, but these may have been deleted from the ship's final configuration. To assist with night landings, the arrester wires were to be illuminated with neon lights.

Two 4 m (13 ft) high, slitted steel wind barriers were installed afore the midships and forward elevators. These were designed to reduce wind velocity over the flight deck to a distance of approximately 40 m (130 ft) behind them. When not in use they would have been lowered flush with the deck to allow aircraft to pass over them.

The Graf Zeppelins' starboard-side island housed the command and navigating bridges and charthouse. It also served as a platform for three searchlights, four domed stabilized fire-control directors and a large vertical funnel. To compensate for the weight of the island, the carrier's flight deck and hangars were offset 0.5 m (1 ft 8 in) to port from her longitudinal axis. Design additions proposed in 1942 included a tall fighter-director tower, air search radar antennas and a curved cap for her funnel, the latter intended to keep smoke and exhaust gases away from the armored fighter-director cabin.

Armament

The Graf Zeppelins were to be armed with separate high and low angle guns for AA and anti-ship defense at a time when most other major navies were switching to dual-purpose AA weapons and relying on escort ships to protect their carriers from surface threats. Her primary anti-shipping armament consisted of sixteen 15 cm (5.9 in) guns paired in eight armored casemates. These were mounted, two each, at the four corners of the carriers' upper hangar deck, positions that raised the possibility the guns would be washed out in heavy seas, especially those in the forward casemates.

Chief Engineer Hadeler had originally planned for only eight such weapons on the carriers, four on each side in single mountings. However, the Naval Armaments Office misinterpreted his proposal to save space by pairing them and instead doubled the number of guns to sixteen, resulting in a need for increased ammunition stowage and more electrically-operated hoists to service them. Later in Graf Zeppelin's construction, some consideration was given to deleting these guns and replacing them with 10.5 cm (4.1 in) guns mounted on sponsons just below flight deck level. But the structural modifications needed to accommodate such a change were judged too difficult and time-consuming, requiring major changes to the ship’s design, and the matter was shelved.

Primary AA protection came from 12 10.5 cm (4.1 in) guns, paired in six turrets positioned three afore and three aft of the carrier’s island. Potential blast damage to planes sited on the flight deck when these guns fired to port was an unavoidable risk and would have limited any flight activity during an engagement.

The Graf Zeppelin class's secondary AA defenses consisted of 11 twin 37 mm (1.5 in) SK C/30 guns mounted on sponsons located along the flight deck edges: four on the starboard side, six to port and one mounted on the ship's forecastle. In addition, seven 20 mm (0.79 in) MG C/30 guns were installed on single-mount platforms on either side of the carrier: four to port and three to starboard. These guns were later changed on Graf Zeppelin to quadruple mountings.

Travemünde

In 1937, with Graf Zeppelin’s launch scheduled for the end of the following year, the Luftwaffe’s experimental test facility at Travemünde (Erprobungsstelle See or E-Stelle See) on the Baltic coast began a lengthy program of testing prototype carrier aircraft. This included performing simulated carrier landings and take-offs and training future carrier pilots.

The runway was painted with a contoured outline of Graf Zeppelin’s flight deck and simulated deck landings were then conducted over an arresting cable strung width-wise across the airstrip. The cable was attached to an electromechanical braking device manufactured by DEMAG. Testing began in March 1938 using the Heinkel He 50, Arado Ar 195 and Ar 197. Later, a stronger braking winch was supplied by Atlas-Werke of Bremen and this allowed heavier aircraft, such as the Fieseler Fi 167 and Junkers Ju 87, to be tested. After some initial problems, Luftwaffe pilots performed 1,500 successful braked landings out of 1,800 attempted.

Launches were practiced using a 20 m (66 ft) long barge-mounted pneumatic catapult, moored in the Trave River estuary. The Heinkel-designed catapult, built by Deutsche Werke Kiel (DWK), could accelerate aircraft to speeds of 145 km/h (90 mph) depending on wind conditions. Test planes were first hoisted by crane onto collapsible launch carriages in the same manner as intended on Graf Zeppelin.

The catapult test program began in April 1940 and, by early May, 36 launches had been conducted, all carefully documented and filmed for later study: 17 by Arado Ar 197s, 15 by modified Junkers Ju 87Bs and four using a modified Messerschmitt Bf 109D. Further testing followed and by June Luftwaffe officials were fully satisfied with the catapult system’s performance.

Aircraft

The expected role of the Graf Zeppelin class was that of a sea-going scouting platform and her initial planned air group reflected that emphasis: 20 Fieseler Fi 167 biplanes for scouting and torpedo attack, 10 Messerschmitt Bf 109 fighters, and 13 Junkers Ju 87 dive-bombers. This was later changed to 30 Bf 109 fighters and 12 Ju 87 dive-bombers as carrier doctrine in Japan, Great Britain and the United States shifted away from purely reconnaissance duties towards offensive combat missions.

Messerschmitt Bf 109 T

In the fall of 1938, the Technische Amt RLM (Technical Office of the Reichsluftfahrtministerium or State Ministry of Aviation) requested that Messerschmitt’s Augsburg design bureau draw up plans for a carrier-borne version of the Bf 109 E fighter, to be designated Bf 109 T (the "T" standing for Träger or Carrier). The resulting aircraft, nicknamed 'Toni' by its pilots, was powered by a Daimler-Benz DB 601N 1,175 PS engine, giving it a maximum speed of 568 km/h (353 mph) at 20,000 feet (6,100 m). Armament comprised two fuselage-mounted 7.92 mm (0.312 in) MG 17 machine guns with two additional MG 17s or 20mm MG FF/M cannons in the wings.

Wing area was increased through the addition of two 0.6 m (2 ft 0 in) outer panels, extending overall span to 11 m (36 ft), and retractable spoilers were fitted to the upper wing surfaces. This significantly shortened the aircraft’s normal take-off and landing runs, improved low-speed stability and allowed for steeper glide angles.

Bf 109T-1

Four catapult attachment points were added to the fuselage and an arrester hook to the tail. The arrester hooks were later widened to minimize bending of the arresting cables when landing. The hooks also tended to bounce against the fuselage, causing dents. This problem was remedied by incorporating a metal spring into the design and adding a rubber buffer pad to the rear fuselage.

An under-fuselage ETC rack was fitted for carrying a 300 litres (66 imp gal; 79 US gal) center-line drop-tank. The undercarriage oleo legs were also strengthened to better absorb the higher descent rates and greater stresses associated with carrier landings. Thicker head and armrest padding in the cockpit improved pilot comfort when making catapult launches. No provision was made for wing-folding on the Bf 109 T as it was considered unnecessary since the aircraft easily fit within the 14 m (46 ft) width of Graf Zeppelin's elevators.

After acceptance by the RLM in early 1939, the project was turned over to Fieseler-Werke for final details and the conversion of 60 Bf 109E airframes into T-1s. This order was progressively increased to 155 machines by September but, with work on Graf Zeppelin's sister carrier, Flugzeugträger B, suspended that same month, planned production reverted to an initial batch of 70 aircraft. By December 1940, the RLM decided to complete only seven carrier-equipped Bf 109 T-1s and to finish the remainder as land-based T-2s since work on Graf Zeppelin had ceased back in April and there appeared to be little likelihood she would then be commissioned any time soon.

Due to delays in production of the Bf 109 E series in mid-1940, design alterations to the plane's wing spar and Daimler Benz's slow delivery of the promised DB 601N engines, the first Bf 109 T-1 was not delivered until January 1941. By June, however, all 70 machines were completed. One T-1 was sent to E-Stelle See in Travemünde for evaluation and six more were reserved for further testing. The remaining 63 T-2s were then ferried to Norway via Denmark and served in I/JG 77 and JGr Trondheim where their short take-off and landing characteristics made them ideally suited to that country’s small windswept airstrips.

At the end of 1941, when interest in completing Graf Zeppelin revived, the surviving Bf 109 T-2s were withdrawn from front-line service in order to again prepare them for possible carrier duty. Seven T-2s were rebuilt to T-1 standards and handed over to the Kriegsmarine on 19 May 1942. By December, a total of 48 Bf 109 T-2s had been converted back into T-1s. 46 of these were stationed at Pillau in East Prussia and reserved for use aboard the carrier. By February 1943, however, all work on Graf Zeppelin had ceased and the aircraft were returned to Luftwaffe service in April.

Fieseler Fi 167

In competition with Arado, Fieseler Werke submitted a design in 1937 at the request of the Technische Amt for a two-seater multi-purpose carrier plane capable of performing bombing, torpedo bombing and reconnaissance duties. Fieseler’s submission, the Fieseler Fi 167 (nicknamed “Dragonfly”) was a lean-looking biplane powered by an inline 1,100 PS Daimler-Benz DB601B engine. This gave it a maximum speed of 320 km/h (200 mph) and a much sleeker appearance than Arado’s radial-engined entry, the Ar 195. Fieseler's plane featured folding wings for carrier stowage, an arrester hook, an enclosed cockpit for a crew of two, a fixed undercarriage (which could be jettisoned in the event of an emergency water landing by electrically triggering two sets of spring-loaded bolts) and full-span automatic leading edge slats along the upper and lower wings, with the lower wings also sporting large trailing edge flaps. These latter features gave the plane unparalleled stability at low speeds.

A Fieseler Fi 167, the fifth of 12 pre-production machines, banks through the clouds on a test flight.

Armament consisted of a maximum bomb load of one 1,000 kg (2,200 lb) bomb or a standard 764 kg (1,684 lb) LT F 5b torpedo plus one forward-firing 7.92 mm (0.312 in) MG 17 machine mounted over the engine cowling and one 7.92 mm MG 15 machine gun on a flexible mount in the rear cockpit to be operated by the observer/navigator. Normal operating range (with bomb load) was1,300 km (810 mi) but this could be extended to 1,500 km (930 mi) for reconnaissance missions with the addition of a 300 L (66 imp gal; 79 US gal) external drop-tank.

Comparative testing at the Luftwaffe's Erprobungsstelle Rechlin test facility quickly demonstrated the Fi 167's superiority to the Ar 195 in all respects, so much so that Fieseler opted to forego constructing a third prototype in order to begin assembly of twelve pre-production machines. Since Graf Zeppelin would not be ready for sea trials until summer 1940, however, work on the pre-production order proceeded at a desultory pace and it was not until spring 1940 that the first example, Fi 167 A-01, began flight testing.

When work on Graf Zeppelin was suspended in May 1940, the 12 completed Fi 167s were organized into Erprobungsstaffel 167 for the purpose of conducting further operational trials. By the time work on the carrier resumed two years later in May 1942, the Fi 167 was no longer considered adequate for its intended role and the Technische Amt decided to replace it with a modified torpedo-carrying version of the Junkers Ju 87D.

Junkers Ju 87 C

In 1938 the Technische Amt decided to include a squadron (Staffel) of dive-bombers in the Graf Zeppelins' air groups, the obvious choice being the combat-proven Junkers Ju 87 Stuka. Work on converting the Ju 87 B into the carrier version Ju 87 C began later that year. Pre-production Ju 87Cs had manually folded wings, reducing carrier stowage width to just 5 m (16 ft); production series aircraft featured an electrically-actuated wing folding mechanism. Overall wingspan was 0.6 m (2 ft 0 in) shorter than the Ju 87 B. Catapult attachment points were added to the lower fuselage and an arrester hook was installed just forward of the tail wheel. The fuselage and landing gear were also strengthened to better withstand the stresses of carrier landings. The two propeller-driven sirens normally mounted on the Stuka’s fixed undercarriage legs were deleted, which helped reduce drag.

The Ju 87 C’s fixed landing gear could be jettisoned via explosive charges in the event it had to ditch over water. This would help minimize the likelihood of the plane flipping over as it touched down. Flotation bags in the body and wings of the plane were installed and sealants applied to seams and openings to delay the aircraft’s sinking should it be forced to make a water landing, thereby giving the crew sufficient time to exit the cockpit and deploy the inflatable rubber dinghy stowed on board for just such emergencies.

Internal fuel stowage was increased with the addition of two auxiliary wing tanks and could be further augmented by attaching two 300 litres (66 imp gal; 79 US gal) external drop-tanks to the wing undersides. This extended the aircraft’s maximum range to over 1,100 kilometres (680 mi). In an emergency, all fuel could be dumped in approximately one minute.

Powered by a Junkers Jumo 211D 1,200 PS engine, the Ju 87 C had a top speed of 332 km/h (206 mph). Armament comprised a maximum bomb load of 700 kg (1,500 lb), two fixed forward-firing 7.92 mm (0.312 in) MG 17 machine guns in the wings and one flexible 7.92 mm MG 15 machine gun mounted in the rear cockpit, manned by the navigator/radio operator.

Ten Ju 87 C-0 pre-production aircraft were built and sent to the testing facilities at Rechlin and Travemünde where they underwent extensive service trials, including catapult launches and simulated deck landings. But of the 170 Ju 87 C-1 ordered, only a few saw completion, suspension of work on Graf Zeppelin in May 1940 resulting in cancellation of the entire order. Existing aircraft and those airframes in process were eventually converted back into Ju 87 B-2s.

Junkers Ju 87 E

Work on developing a torpedo-carrying version of the Ju 87 D for anti-shipping sorties in the Mediterranean had already commenced in early 1942 when the possibility again arose that Graf Zeppelin might be completed. As the Fieseler Fi 167 was now considered obsolete, the Technische Amt requested that Junkers modify the Ju 87 D-4 into a carrier-borne torpedo-bomber/recon plane to be designated Ju 87 E-1. Production aircraft would have electrically-actuated folding wings and receive the same carrier fittings as applied to the Ju 87 C as well as attachment points for a 764 kg (1,684 lb) LT F 5b torpedo. Consideration was also given to fitting the aircraft with rocket-assisted take-off gear (RATOG) in order to shorten its take-off run on the carrier.

Testing was conducted in the spring and summer of 1942 at Erprobungsstelle See in Travemünde and the results were sufficiently satisfactory that the RLM issued an order for 115 machines. But when all further work on Graf Zeppelin was halted for good in February 1943, the entire order was canceled. None of the Ju 87 Ds converted to carry a torpedo were used operationally.

Messerschmitt Me 155

By May 1942, when work was ordered resumed on Graf Zeppelin, the older Bf 109T carrier-borne fighter was considered obsolete. Consequently, the Technische Amt invited Messerschmitt A.G. to submit new design proposals for a shipboard fighter designated Me 155. Emphasis was placed on using current Bf 109 components for ease of manufacturing and to limit the workload on Messerschmitt's busy design staff. By September 1942 detailed plans were completed.

The Me 155 utilized a standard Bf 109 G airframe wedded to a newly-designed wing, capable of folding for carrier stowage. The wing retained the same span as that of the Bf 109 G, 11 m (36 ft), however the designers replaced the Bf 109 G's narrow outward-retracting main landing gear with a wide-track inward-retracting undercarriage, giving the plane more stable landing characteristics. This was especially desirable in an aircraft expected to negotiate the restricted width of a pitching carrier deck. Catapult attachment points, an arrester hook and flotation gear were also added. Proposed armament consisted of an engine-mounted 20 mm (0.79 in) MG 151 cannon plus two 20 mm MG 151s and two 13 mm (0.51 in) MG 131 machine guns in the wings. Powered by a DB 605A-1 engine rated at 1,475 PS, the aircraft was expected to attain a top speed of 649 km/h (403 mph) with a calculated endurance of 1.16 hours (minus external drop-tank).

When it became apparent Graf Zeppelin would not be commissioned for at least another two years, Messerschmitt was unofficially told to shelve the projected fighter design. No prototype of the carrier-borne version of the plane was ever constructed.

1940–1945

Graf Zeppelin moored at Stettin, summer 1941. Note the improved "Atlantic prow", the two empty openings for the 15cm gun casemates (just below and forward of the funnel), the telescoping masts and the ends of the twin catapult tracks on the flight deck.

Construction on the Kriegsmarine's two aircraft carriers had been fitful from the start due to a shortage of welders and delays in obtaining materials. Work on Flugzeugträger B was finally halted on 19 September 1939 because, now that Germany was at war with Great Britain and France, priority had shifted to U-boat construction. The hull, completed only up to the armored deck, sat rusting on its slipway until 28 February 1940, when Admiral Raeder ordered her broken up and scrapped.

Meantime, Germany’s conquest of Norway in April 1940 further eroded any chance of completing Flugzeugträger A (Graf Zeppelin). Now responsible for defending Norway’s long coastline and numerous port facilities, the Kriegsmarine urgently required large numbers of coastal guns and AA batteries. During a naval conference with Hitler on 29 April 1940, Admiral Raeder proposed halting all work on Graf Zeppelin, arguing that even if she was commissioned by the end of 1940, final installation of her guns would require another ten months or more (her original fire control system had been sold to the Soviet Union under an earlier trade agreement). Hitler consented to the stop work order, allowing Raeder to have Graf Zeppelin’s 15 cm guns removed and transferred to Norway. The carrier’s heavy flak armament of twelve 10.5 cm guns had already been diverted elsewhere.

On 12 July 1940, Graf Zeppelin was towed from Kiel to Gotenhafen (Gdynia) and remained there for nearly a year. Just prior to Germany's invasion of the Soviet Union in June 1941, the carrier was again moved, this time to Stettin, in order to safeguard her from Soviet air attacks. By November, the German army had pushed deep enough into Russian territory to remove any further threat of air attack and Graf Zeppelin was returned to Gotenhafen where she briefly served as a floating warehouse for the Navy's hardwood supply.

By the time Admiral Raeder met with Hitler for a detailed discussion of naval strategy in April 1942, the usefulness of aircraft carriers in modern naval warfare had been amply demonstrated. British carriers had crippled the Italian fleet at Taranto in November 1940, critically damaged the German battleship Bismarck in May 1941 and prevented battleship Tirpitz from attacking two convoys bound for Russia in March 1942. In addition, a Japanese carrier raid on Pearl Harbor had devastated the American battlefleet in December 1941. Raeder, anxious to secure air protection for the Kriegsmarine's heavier surface units, informed Hitler that Graf Zeppelin could be finished in about a year, with another six months required for sea trials and flight training. On 13 May 1942, with Hitler's authorization, the German Naval Supreme Command ordered work resumed on the carrier.

But daunting technical problems remained. Raeder wanted newer planes, specifically designed for carrier use. Reichsmarschall Goering, head of the Luftwaffe, replied that the already overburdened German aircraft industry could not possibly complete the design, testing and mass production of such aircraft before 1946. Instead, he proposed converting existing aircraft (again the Junkers Ju 87 and Messerschmitt Bf 109) as a temporary solution until newer types could be developed. Training of carrier pilots at Travemünde would also resume.

The converted carrier aircraft were heavier versions of their land-based predecessors and this required a host of changes to Graf Zeppelin's original design: the existing catapults needed modernization; stronger winches were necessary for the arresting gear; the flight deck, elevators and hangar floors also required reinforcement. Changes in naval technology dictated other alterations as well: installation of air search radar sets and antennas; upgraded radio equipment; an armored fighter director cabin mounted on the main mast (which in turn meant a heavier sturdier mast to accommodate the cabin's added weight); extra armoring for the bridge and fire control center; a new curved funnel cap to shield the fighter director cabin from smoke; replacing the single-mount 20mm AA guns with quadruple Flakvierling 38 guns (with a corresponding increase in ammunition supply) to improve overall AA defense; and additional bulges on either side of the hull to preserve the ship's stability under all this added weight.

The German naval staff hoped all these changes could be accomplished by April 1943, with the carrier's first sea trials taking place in August that same year. Towards that end, Chief Engineer Hadeler was reassigned to oversee Graf Zeppelin's completion. Hadeler planned on getting the two inner shafts and their respective propulsion systems operational first, giving the ship an initial speed of 25-26 knots, fast enough for sea trials to commence and for conducting air training exercises. By the winter of 1943/1944 she was expected to be combat-ready.

On the night of 27–28 August 1942, Graf Zeppelin underwent the only Allied air attack ever specifically targeting her for destruction. Nine RAF Lancaster bombers from 106 and 97 Squadrons were despatched against Gotenhafen, each one carrying single "Capital Ship" bombs, a 5,500 lb device with a shaped charge warhead intended for armoured targets. One pilot was unable to see the carrier due to haze and instead dropped his bomb on the estimated position of the German battleship Gneisenau. Another believed he scored a direct hit on Graf Zeppelin but there is no known record of the ship suffering any damage from a bomb strike that night.

On 5 December 1942, Graf Zeppelin was towed back to Kiel and placed in a floating drydock. It seemed she might well see completion after all. By late January 1943, however, Hitler had become so disenchanted with the Kriegsmarine, especially with what he perceived as the poor performance of its surface fleet, that he ordered all of its larger ships taken out of service and scrapped. To Admiral Raeder, who had often clashed with Hitler on naval policy, this was a stunning setback. In a long memorandum to Hitler he called the new order "the cheapest sea victory England ever won". Raeder was shortly relieved of command and replaced with former Commander of Submarines Karl Dönitz. Though Admiral Dönitz eventually persuaded Hitler to void most of the order, work on all new surface ships and even those nearing completion was halted, including Graf Zeppelin. As of 2 February 1943, construction on the carrier ended for good.

In April 1943 Graf Zeppelin was towed eastward, first to Gotenhafen, then to the roadstead at Swinemünde and finally berthed at a wharf in the Parnitz River, two miles (3 km) from Stettin. There she languished for the next two years with only a 40-man custodial crew in attendance. When Red Army forces neared the city in April 1945, the ship's Kingston valves were opened, flooding her lower spaces and settling her firmly into the mud in shallow water. A ten-man engineering squad then rigged the vessel's interior with demolition and depth charges in order to hole the hull and destroy vital machinery. At 6pm on 25 April 1945, just as the Russians entered Stettin, commander Wolfgang Kähler radioed the squad to detonate the explosives. Smoke billowing from the carrier's funnel confirmed the charges had gone off, rendering the ship useless to her new owners for many months to come.

See also

• List of aircraft carriers
• List of World War II ships
• List of naval ships of Germany
• List of naval ship classes of Germany
• List of Kriegsmarine ships
• List of ship launches in 1938
• Flugzeugträger B - Graf Zeppelin's sister ship

Bibliography

• Barker, Lt. Cmdr Edward L. (1954). "War Without Aircraft Carriers". United States Naval Institute Proceedings. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |month= ignored (help)
• Breyer, Siegfried (1989). The German Aircraft Carrier Graf Zeppelin. Atglen, Pennsylvania: Schiffer Publishing Ltd.
• Breyer, Siegfried (2004). Encyclopedia of Warships 42: Graf Zeppelin. Gdansk: A.J. Press.
• Brown, David (1977). WWII Fact Files: Aircraft Carriers. New York: Arco Publishing.
• Burke, Stephen (Sept 2007). Without Wings: The Story of Hitler's Aircraft Carrier. Trafford Publishing. ISBN 1425122167. {{cite book}}: Check date values in: |year= (help)
• Green, William (1979). The Warplanes of the Third Reich. New York: Doubleday and Company, Inc.
• Green, William (1994). The Complete Book of Fighters. Salamander Books. ISBN 0-8317-3939-8. {{cite book}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
• Israel, Ulrich H.-J. (1994). Graf Zeppelin: Einziger Deutscher Flugzeugträger. Hamburg: Verlag Koehler/Mittler.
• Israel, Ulrich H.-J. (2003). ""Flugdeck klar!" Deutsche Trägerflugzeuge bis 1945". Flieger Revue Extra. {{cite journal}}: Cite journal requires |journal= (help)
• Lake, Jon (2002). Lancaster Squadrons 1942-43. Osprey. ISBN 1841763136.
• Marshall, Francis L. (1994). Sea Eagles - The Operational History of the Messerschmitt Bf 109T. Walton on Thames, Surrey, UK: Air Research Publications.
• Reynolds, Clark G. (1967). "Hitler's Flattop: The End of the Beginning". United States Naval Institute Proceedings. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |month= ignored (help)
• Smith, Peter C. (1998). Junkers Ju 87 Stuka. Ramsbury: The Crowood Press.
• Whitley, M.J. (1984). "Warship 31: Graf Zeppelin, Part 1". London: Conway Maritime Press Ltd. {{cite journal}}: Cite journal requires |journal= (help); Unknown parameter |month= ignored (help)
• Whitley, M.J. (1985). Warship 33, Vol IX: Graf Zeppelin, Part 2. London: Conway Maritime Press Ltd.

External links

• Graf Zeppelin images from Bundesarchiv Freiburg (text in German but lots of images)
• Maritimequest Graf Zeppelin photo gallery
• "Graf Zeppelin Rediscovered—Hitler's Showpiece Aircraft Carrier Found." Spiegel Online International article dated 27-7-2006. Retrieved 20-9-2010.