Design Graf Zeppelin-class aircraft carrier

1 design

1.1 hull
1.2 machinery
1.3 flight deck & hangars

1.3.1 hangars
1.3.2 elevators
1.3.3 launch catapults
1.3.4 arresting gear
1.3.5 wind barriers
1.3.6 island


1.4 armament

design
hull

the graf zeppelin @ kiel, june 1940, displaying newly rebuilt bow. visible 15 cm casemate guns, before removal defend occupied norway. photo marked geheim ( secret ).

the graf zeppelin class s hull divided 19 watertight compartments, standard division capital ships in kriegsmarine. belt armor vary 100 mm (3.9 in) on machinery spaces , aft magazines, 60 mm (2.4 in) on forward magazines , tapered down 30 mm (1.2 in) @ bows. stern armor kept @ 80 mm (3.1 in) protect steering gear. inboard of main armor belt 20 mm (0.79 in) anti-torpedo bulkhead.

horizontal armor protection against aerial bombs , plunging shellfire started flight deck, acted main strength deck. armor 20 mm (0.79 in) thick except areas around elevator shafts , funnel uptakes thickness increased 40 mm (1.6 in) in order give elevators necessary structural strength , critical uptakes greater splinter protection. beneath lower hangar main armored deck (or tween deck) armor thickness varied 60 mm (2.4 in) on magazines 40 mm (1.6 in) on machinery spaces. along peripheries, formed 45 degree slope joined lower portion of waterline belt armor.

the graf zeppelins original length-to-beam ratio 9.26:1, resulting in slender silhouette. however, in may 1942, accumulating top-weight of recent design changes required addition of deep bulges either side of graf zeppelin s hull, decreasing ratio 8.33:1 , giving widest beam of carrier designed prior 1942. bulges served improve graf zeppelin s stability gave added degree of anti-torpedo protection , increased operating range because selected compartments designed store approximately 1500 tons more fuel oil.

graf zeppelin s straight-stemmed prow rebuilt in 1940 addition of more sharply angled atlantic prow , intended improve overall seakeeping. added 5.2 m (17 ft) overall length.

machinery

the graf zeppelin class s power plant consist of 16 la mont high-pressure boilers, similar used in admiral hipper-class heavy cruisers. 4 sets of geared turbines, connected 4 shafts, expected produce 200,000 shp (150,000 kw) , propel carrier @ top speed of 35 knots (40 mph; 65 km/h). maximum bunkerage capacity of 5000 tons of fuel oil (prior addition of bulges in 1942), graf zeppelins calculated radius of action 9,600 miles (15,400 km) @ 19 knots (35 km/h; 22 mph). however, wartime experience on ships similar power plants showed such estimates highly inaccurate, , actual operational ranges tended lower.

two voith-schneider cycloidal propeller-rudders installed in forward bow of ship along center-line. these intended assist in berthing ship in harbor , in negotiating narrow waterways such kiel canal where, due carrier s high freeboard , difficulty in maneuvering @ speeds below 8 knots (15 km/h; 9.2 mph), gusting winds might push ship canal sides. in emergency, units have been used steer ships @ speeds under 12 knots (22 km/h; 14 mph) and, if ships main engines rendered inoperable, propel vessel @ speed of 4 knots (7.4 km/h; 4.6 mph) in calm seas. when not in use, retracted vertical shafts , protected water-tight covers.

flight deck & hangars

the graf zeppelins steel flight deck, overlaid wooden planking, 242 m (794 ft) long 30 m (98 ft) wide @ maximum. had slight round down right aft , overhung main superstructure not stern; being supported steel girders. @ bow, carriers have open forecastle , leading edge of flight deck uneven (mainly due blunt ends of catapult tracks), did not appear have caused undue air turbulence. careful wind-tunnel studies using models confirmed this, revealed long low island structure generate vortex on flight deck in these tests when ship yawed port. considered acceptable hazard when conducting air operations.

hangars

the graf zeppelin class s upper , lower hangars long , narrow unarmored sides , ends. workshops, stores , crew quarters located outboard of hangars, design feature similar of british carriers. upper hangar measured 185 m (607 ft) x 16 m (52 ft); lower hangar 172 m (564 ft) x 16 m (52 ft). upper hangar had 6 m (20 ft) vertical clearance while lower hangar had 0.3 m (1 ft 0 in) less headroom due ceiling braces. total usable hangar space 5,450 m (58,700 sq ft) stowage 43 aircraft: 20 fieseler fi 167 torpedo bombers, 18 in lower hangar, 2 in upper hangar; 13 junkers ju 87c dive bombers in upper hangar , 10 messerschmitt bf 109t fighters in upper hangar.

elevators

the graf zeppelin class had 3 electrically operated elevators positioned along flight-deck s center-line: 1 near bow, abreast forward end of island; 1 amidships; , 1 aft. octagonal in shape, measuring 13 m (43 ft) x 14 m (46 ft), , designed transfer aircraft weighing 5.5 tons between decks.

launch catapults

two deutsche werke compressed air-driven telescoping catapults installed @ forward end of flight deck power-assisted launches. 23 m (75 ft) long , designed accelerate 2,500 kg (5,500 lb) fighter speed of approximately 140 km/h (87 mph) , 5,000 kg (11,000 lb) bomber 130 km/h (81 mph).

a dual set of rails led catapults forward , midship elevators. in hangars, aircraft hoisted crane - method proposed essex-class carriers of united states navy, rejected time-consuming - onto collapsible launch trolleys. aircraft/trolley combination lifted flight deck level on elevator , trundled along rails catapult start points. when catapults triggered, burst of compressed air propel moveable slideways within catapult track wells forward.

as each plane lifted off, launch trolley reach end of slideway remain locked in place until tow attachment cables released. once slideways retracted catapult track wells , tow cables unhooked, launch trollies manually pushed forward onto recovery platforms, lowered forecastle on b deck, rolled upper hangar re-use via secondary set of rails. when not in use, catapult tracks covered sheet metal farings protect them harsh weather.

eighteen aircraft have theoretically been launched @ rate of 1 every 30 seconds before exhausting catapult air reservoirs. have taken 50 minutes recharge reservoirs. 2 large cylinders holding compressed air housed in insulated compartments located between 2 catapult tracks, below flight deck level above main armored deck. positioning afforded them light protection potential battle damage. insulated compartments electrically heated temperature of 20 °c (68 °f) in order prevent ice forming on cylinder piping , control equipment compressed air vented during launches.

it intended outset of graf zeppelins aircraft launch via catapult. rolling take-offs performed in emergency or if catapults inoperable due battle damage or mechanical failure. whether practice have been strictly adhered or later modified, based on actual air trials , combat experience open question, given limited capacity of air reservoirs , long recharging times necessary between launches. 1 advantage of such system, however, graf zeppelins have launched aircraft without need turning ship wind or under conditions prevailing winds light provide enough lift heavier aircraft. have launched , landed aircraft simultaneously.

to facilitate rapid catapult launches , eliminate necessity of time-consuming engine warm-ups, 8 aircraft kept in readiness aboard german carriers on hangar decks use of steam pre-heaters. these keep aircraft engines @ operational temperature of 70 °c (158 °f). in addition, engine oil kept warmed in separate holding tanks, added via hand-pumps aircraft engines shortly before launch. once aircraft raised flight deck level via elevators, aircraft oil temperature maintained, if need be, through use of electric pre-heaters plugged power points on flight deck. otherwise, aircraft have been catapult-launched engines have been @ or near normal operating temperature.

arresting gear

four arrester wires positioned @ after end of flight deck 2 more emergency wires located afore , abaft of amidships elevator. original drawings show 4 additional wires fore , aft of forward lift, possibly intended allow recovery of aircraft on bows, these may have been deleted ship s final configuration. assist night landings, arrester wires illuminated neon lights.

wind barriers

two 4 m (13 ft) high, slitted steel wind barriers installed afore midships , forward elevators. these designed reduce wind velocity on flight deck distance of approximately 40 m (130 ft) behind them. when not in use lowered flush deck allow aircraft pass on them.

island

the position of graf zeppelins superstructure in relation flight deck.

the graf zeppelins starboard-side island housed command , navigating bridges , charthouse. served platform 3 searchlights, 4 domed stabilized fire-control directors , large vertical funnel. compensate weight of island, carrier s flight deck , hangars offset 0.5 m (1 ft 8 in) port longitudinal axis. design additions proposed in 1942 included tall fighter-director tower, air search radar antennas , curved cap funnel, latter intended keep smoke , exhaust gases away armored fighter-director cabin.

armament

the graf zeppelins armed separate high , low angle guns aa , anti-ship defense @ time when other major navies switching dual-purpose aa weapons , relying on escort ships protect carriers surface threats. primary anti-shipping armament consisted of sixteen 15 cm (5.9 in) sk c/28 guns paired in 8 armored casemates. these mounted, 2 each, @ 4 corners of carriers upper hangar deck, positions raised possibility guns washed out in heavy seas, in forward casemates.

chief engineer hadeler had planned 8 such weapons on carriers, 4 on each side in single mountings. however, naval armaments office misinterpreted proposal save space pairing them , instead doubled number of guns 16, resulting in need increased ammunition stowage , more electrically operated hoists service them. later in graf zeppelin s construction, consideration given deleting these guns , replacing them 10.5 cm (4.1 in) sk c/33 guns mounted on sponsons below flight deck level. structural modifications needed accommodate such change judged difficult , time-consuming, requiring major changes ship s design, , matter shelved.

primary aa protection came 12 10.5 cm (4.1 in) guns, paired in 6 turrets positioned 3 afore , 3 aft of carrier s island. potential blast damage planes sited on flight deck when these guns fired port unavoidable risk , have limited flight activity during 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 flight deck edges: 4 on starboard side, 6 port , 1 mounted on ship s forecastle. in addition, 7 20 mm (0.79 in) mg c/30 guns installed on single-mount platforms on either side of carrier: 4 port , 3 starboard. these guns later changed flakvierling mountings.

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