German Aircraft Carrier of WW2
By Stephen Sherman, June, 2011. Updated March 1, 2012.
The Graf Zeppelin was the ultimate white elephant, a huge and expensive naval vessel that her owners (Nazi Germany) never knew what to do with, never finished, and never really wanted in the first place. While inter-service rivalries have always complicated military planning and procurement, the rivalry between the Luftwaffe and the Kriegsmarine was unmatched. Goering had not risen to be Hitler's Number Two for no reason, and the less political Admiral Raeder was out of his depth in inter-service politicking. There were endless difficulties with the carrier.
It was a ship that was filled with contradictions and compromises from the start. She was outfitted with six-inch guns that had no business on an aircraft carrier, which were ultimately sent to Norway for coastal defense. Her aircraft were half-hearted modifications of land-based planes, most of which never reached production. Her propulsion was vastly overpowered: 200,000 HP for a ship with 40 airplanes. (American Essex-class carriers of the era were rated at 150,000 HP and carried almost 100 aircraft.)
In 1935, Germany signed a naval treaty with Britain which permitted it to build two carriers of just under 20,000 tons each. While Germany was not a naval power like Britain, Japan, or the United States, and had no real strategic need to project naval air power, Hitler's grandiose ambitions embraced all big, new, powerful weapons, and two aircraft carriers were authorized that same year: identified as Flugzeugträger "A" and Flugzeugträger "B" (Carrier A and Carrier B), per Kriegsmarine practice of not naming ships until launching. The German contractors, Deutsche Werke Kiel A.G, had no experience with aircraft and their unique requirements like flight elevators, catapults, open hangars, etc.. They did consult with the Japanese, and were licensed flight deck equipment from the carrier Akagi.
As the Kiel shipyard was committed to building other ships, Flugzeugträger "A," was not laid down until December, 1936. Two years later, on December 8, 1938, she was launched and christened Graf Zeppelin, in honor of the great German airship pioneer. The second authorized carrier Flugzeugträger "B," never proceeded very far.
When the war started in September 1939, submarines became the priority, and while Graf Zeppelin had been launched and was 85% complete, work on her slowed. On April 29, 1940 after the occupation of Norway, Admiral Raeder re-evaluated the aircraft carrier program. He recommended to Hitler that Flugzeugträger "B" (notionally the "Peter Strasser") be abandoned and broken up. As for Graf Zeppelin, he proposed that her 6-inch guns be dispatched to Norway for use as coastal artillery. Hitler agreed. Her 4-inch anti-aircraft guns had already been re-assigned to other ships. And her fire control system was sold to the Soviet Union. There was to be no further work on the ship, which would be moved from Kiel to Gotenhafen in East Prussia (now Gdynia, Poland), where it would be less exposed to British air attacks. On July 6, 1940, in "Operation Zugvogel" (migratory bird) Graf Zeppelin was towed to the Baltic port.
Hitler's penchant for invading other countries kept the Graf Zeppelin moving, although not as a functional aircraft carrier. She stayed at Gotenhafen for almost a year, but June, 1941, with the invasion of Russia imminent, she was moved to Stettin, to be a little farther away from the Russians. By November, the Germans had pushed deep into Russia, and it was deemed safe enough for Graf Zeppelin to return to Gotenhafen. During this time, her capacious hangar decks served as a storehouse for the Kriegsmarine's supply of wood. (My Dad served in the US Navy in World War Two, and I was surprised at his mention of lumber, carpenters, and wood-working shops that were aboard his ship.)
In April, 1942, Hitler and Raeder had occasion to revive the aircraft carrier program. Japan's stunning attack on the American base naval at Pearl Harbor and on the British capital ships HMS Prince of Wales and HMS Repulse had made a strong impression. And in March, 1942, British naval aircraft had thwarted the Tirpitz' attack on PQ-12 and forced that battleship back to port. Clearly, naval air power was going to be a major factor in the war. They decided to finish construction of the Graf Zeppelin and she was towed back to Kiel in December 1942 for that purpose.
But the proposed completion of the carrier after three years had its own complications. The lessons of the war called for changes in her design. Germany's strained aviation industry would be hard-pressed to develop new airplanes dedicated to naval aviation. At Goering's insistence, modified land-based aircraft would have to suffice. These would be heavier than desirable, which required more changes to the carrier.
All these factors required many changes to Graf Zeppelin's original design:
- modernized catapults;
- stronger winches needed for the arresting gear;
- reinforced flight deck, elevators, and hangar floors;
- new air search radar sets and antennas;
- upgraded radio equipment;
- an armored fighter director cabin (FDC) mounted on the main mast;
- a stronger mast to accommodate the FDC;
- more armor on the bridge and fire control center;
- a funnel cap to shield the FDC from smoke;
- new quadruple Flakvierling 38 guns for better anti-aircraft protection;
- additional bulges on both sides of the hull to preserve stability under the extra weight.
The revised plan was to modify the hull, modernize the catapults, and make half of the mechanical changes by June, 1943. Then, after sea-trials, she would be ready by the winter of 1943-44. The remaining mechanical changes and all-new catapults would be fitted at a late date.
But Hitler's mercurial personality interfered again. In January 1943, in a fit of pique against the perceived failures of the Kriegsmarine, he ordered all its large surface ships to be scrapped and all new construction halted. Admiral Raeder shortly resigned, and was replaced by the submariner, Admiral Dönitz. Dönitz got the most of the order rescinded, but the Graf Zeppelin was over. Work on her stopped in February, 1943, never to be resumed.
From April, 1943 to April, 1945 she sat at Stettin, with only a forty-man skeleton crew. When the Red Army approached, the crew scuttled her and set off explosives destroying her machinery and puncturing her hull, thus rendering her useless to the Russians for nearly two years.
The German designers had no experience with aircraft carriers, so they came with a mixed design, incorporating ideas from various navies and various other ships. She measured 820 feet in overall length, 850 feet at the waterline. Her beam was 88 feet 7 inches, and her maximum draft was 18 feet 4 inches. Like most German capital ships, she was divided into nineteen watertight compartments. The hull bulges proposed in 1942 widened her beam at the waterline, from 88 feet to 98 feet, thus changing her length-to-beam ratio from 9.26:1 to 8.33:1, broader than any other carrier at the time. The bulges not only provided greater stability, but afforded some anti-torpedo protection and allowed more fuel to be carried. Her straight prow was modified in 1940, to a so-called "Atlantic bow," adding 17 feet to her overall length.
The flight deck was 794 feet long, 98 feet at its widest point, with wooden planking covering the steel armor. (Aircraft carriers had wooden flight decks in World War Two; steel would have been hard on the airplanes' rubber tires.) She had two hangar decks, upper and lower. The upper was 607 feet long and 52 feet wide; the lower 564 feet by 52 feet. Note that these hangars were up to 46 narrower than the flight deck. Workshops, crew quarters, and storage occupied the space (up to 23 feet on each side) outboard of the hangars and their aircraft. An interesting design statement, in that crew quarters were located outside the aircraft hangars. Whether this layout implied that expendable crew should serve to protect more valuable aircraft, or merely that the crew should enjoy access to fresh air and sunlight, I do not know. Altogether the two hangar decks had almost 60,000 cubic feet of space, enough to accommodate 41 aircraft.
The Graf Zeppelin featured twin catapults on the forward flight deck. These were 75 feet long and could accelerate her airplanes to 85 MPH. In concept, she would launch her all aircraft with the catapult, rather than by deck take-offs like most other carriers of the day. This idea had some advantages: she could launch aircraft without the necessity of turning into the wind (frequently a tactical problem); she could launch even in a dead calm; and she could launch and recover aircraft simultaneously. Her air-powered catapult was designed to launch up to eighteen aircraft, at a rate of two per minute, before needing to recharge her air compressors. Since the airplanes were intended to be thrown into the air suddenly, the Graf Zeppelin had arrangements to keep both engines and and a supply engine oil hot (158° Fahrenheit). Again, since these designs were never implemented, it cannot be known how well they would have worked in practice.
Light armor covered the flight deck; heavier armor protected the hangar deck and machinery, and the waterline had a belt of varied thickness, 4 inches (100mm) at its thickest.
For an aircraft carrier, the armament was overdone: six twin 4.1 inch anti-aircraft mountings forward and aft of the island, backed up by sixteen 6-inch guns in twin casemates just below the flight deck as protection against surface attack. She also carried eighteen 1.46 inch AA pieces.
Her 6-inch guns (15 centimeter, which is more precisely 5.9 inches) typify the problems of the Graf Zeppelin. Firstly, they seem to have been completely out of place for a carrier designed in the late 1930s. The idea was that they could serve as protection against attack by surface ships, cruisers and destroyers; they also could have been used in commerce raiding if the carrier's airplanes had been used up. It seems like an odd idea in hindsight, but Japan, the United States, and Great Britain all included heavy guns on their earliest carriers. Secondly, the guns were mis-specified. The ship's original included eight guns in single casemates, and Chief Engineer Hadeler suggested they be doubled up to save weight, two guns in four casemates. His request was mis-interpreted, and the total number of guns was doubled to sixteen, which added additional weight to the carrier. Thirdly, as the ship languished and its construction halted in 1940, the guns were stripped, and sent to Norway.
For her size (23,000 tons) she was greatly overpowered, with 200,000 shaft horsepower, capable of making 33.75 knots, while she only carried 40 aircraft. She had 16 LaMont boilers, firing 4 turbines, which powered four propeller shafts, at top speed of 35 knots. Her 5,000 ton supply of fuel oil gave her a theoretical cruising range of 9,600 miles. Actual experience for both speed and range probably would have been less, but since she never put to sea, all we have are the design specifications.
Since Germany had no ongoing naval aviation program and no naval aircraft in 1935, all of Graf Zeppelin's airplanes would have to be developed concurrently, either as modifications of existing land-based aircraft or as all-new naval designs.
Graf Zeppelin's original plans called for twenty Fieseler Fi 167 scout/torpedo biplanes, ten Messerschmitt Bf 109T fighters, and thirteen Junkers Ju 87C/E dive-bombers. This was later changed to 30 fighters and 12 Stuka dive-bombers, as wartime experience had suggested.
In 1937, the Riechsluftfahrtministerium (German Ministry of Aviation) issued a request for a naval strike aircraft, suitable for operations on the Graf Zeppelin. The specification called for a two-seat, multi-role (torpedo bombing, reconnaissance, and dive-bombing) all-metal biplane, capable of flying 300 km/h (186 MPH) while fully loaded. Fieseler and Arado submitted designs, but Fieseler's 167 was soon determined to be much better. It exceeded the design specs. Powered by a single Daimler-Benz DB 601B liquid-cooled, in-line, 1100HP engine, it was capable of 320 km/h (200 MPH) and could carry a 1,000 kg (2,200 lb.) bomb or a standard 1850 lb. torpedo. It featured folding wings for storage in a carrier's hangar, a tail hook, and a fixed landing gear that could be jettisoned in the event of a water landing. It's large lower wing flaps gave it excellent handling at low speeds, and it seemed to be able to descend almost vertically onto the deck. It carried a single forward-facing 7.92 mm MG 17 machine guns and a MG-15 machine gun in the rear. From 1938, Fieseler produced twelve pre-production examples, which of course, never saw service on the unfinished Graf Zeppelin.
When the Graf Zeppelin project was briefly revived in 1942, it was decided that a modified Junkers Ju-87 Stuka would supplant the Fi 167, which was by then out-dated.
Nine were dispatched to a coastal aviation patrol in Holland and were eventually sold to the Nazi puppet government of Croatia. Their STOL (short take-off & landing) characteristics were very useful in the mountainous Balkan terrain. In an interesting historical footnote, an Fi-167 biplane in Croatian service is credited with shooting down a USAAF P-51 Mustang in October 1944, one of the last recorded biplane kills of the war.
In 1938, it was decided to add Stuka dive-bombers to the Graf Zeppelin's air component. Based on the Ju-87B, the "C" model featured folding wings, jettison-able undercarriage, flotation X in the wings, a tail hook, and a catapult attachment. Powered by a Junkers Jumo 211D liquid-cooled in-line engine, its top speed was 332 km/h (206 MPH). It carried a payload of 700 kg (1500 lbs.), and was equipped with three machine guns (two forward-firing 7.92 mm MG 17 machine guns and one rear-facing 7.92 mm MG 15 machine gun). For naval service, the psychological warfare air sirens were removed from the undercarriage. Two prototypes were converted from "B" models and ten pre-production examples were built.
While 170 were authorized in 1939, as the aircraft carrier program faltered in 1940, nowhere near that many were built.
The Ju-87E was the proposed naval variant of the "D" model, which was proposed in 1942 during the brief resurgence of interest in the aircraft carrier.
Originally, the planned fighter for the carrier was to be a variant of Messerschmitt's highly successful and adaptable Bf-109. The "T" was a modified "E" model, with a larger wing, four catapult attachment points, a tail hook, manually folded wings, and a strengthened landing gear. Its guns consisted of two fuselage-mounted 7.92 mm MG 17 machine guns, with provisions for two MG-17 machine guns or two 20-mm MG-FF cannon in the wings. A Daimler Benz DB 601 engine could power the machine to fly at a top speed of 350 MPH.
After the design was accepted by the Kriegsmarine, because of the demand on production at Messerschmitt's Augsburg plant, the program was transferred to Fieseler. Ten Bf 109E-1s were taken off the assembly line and designated Bf 109T-0, as pre-production machines. Sixty Bf 109T-1s were also ordered from Fieseler. However in April, 1940, work on the Graf Zeppelin was halted, and then finally canceled in early 1943. Fieseler finished making the 60 Bf 109T-1s, but without the catapult hooks and arrester gear. Without these carrier features, they were re-designated Bf 109T-2, and were fitted with a ventral bomb rack for various bomb loads. Bf 109T-2 deliveries started in March, 1941, and most were assigned to Norway, another place where carrier-type aircraft were useful on short airfields and in mountainous conditions.
When the Graf Zeppelin was revived in 1942, Messerschmitt was commissioned to design a current fighter for her. The proposed airplane was designated Me 155, basically a navalized Bf 109G, with a tail hook, catapult attachment points, and provisions for folding wings. The power plant and weapons were the same as on the "Gustav" 109: a nose-mounted 20 mm MG 151 cannon plus two 20 mm MG 151s and two 13 mm MG 131 machine guns in the wings. Powered by a DB 605A-1 engine, its rated maximum speed was 649 km/h (403 mph).
The Russians over-ran the naval base at Stettin in April, 1945 and captured the partially-wrecked Graf Zeppelin. For many years, her fate remained a mystery, shrouded behind the military secrecy of the Iron Curtain. After the break-up of the Soviet Union and the opening of its archives, it was revealed that the Soviets had re-floated her, tested her capabilities for a couple years, and sank her with aerial bombing and torpedoes in August, 1947.
The Polish Navy located the wreckage of the Graf Zeppelin in 2006, off the coast of Poland in the Baltic. In May, 2009, the Unified Diving Team spent four days diving to the wreckage, photographing and documenting the remains of the Germany's only aircraft carrier.