Ships of Plan Z:
Flight Deck Cruisers
by Mike Bennighof, Ph.D.
November 2019

During the 1930’s, naval architects working for most major powers sketched cruisers and battleships with flight decks in an attempt to merge the weapons systems of big guns and aircraft. Most of the designs were fanciful and utterly impractical, ignoring the effects of gun turrets and smokestacks on air flow, providing a flight deck far too short for actual operations, or both. No such ship would ever actually be built.

As others abandoned the concept, German designers embraced it: as with a number of trends in warship design, Nazi Germany was well behind the international curve. Having no experience with aircraft carriers beyond some sporadic advice from the Japanese, the Kriegsmarine’s ship designers plowed ahead blindly in their efforts to draft aircraft-carrying ships.

While their wartime conversion designs were more reasonable in terms of gunnery armament, carrying only anti-aircraft weapons, German architects never abandoned the idea of including heavy guns in Germany’s only actual aircraft carrier, Graf Zeppelin. So the mix of guns and aircraft was not a new concept to the Germans.

Adolf Hitler appears to have suggested to Admiral Erich Raeder in July 1940 that an aircraft-carrying cruiser would make an effective commerce raider. The naval construction office replied to Raeder’s inquiries that the hull of an M-class light cruisers could be converted into such a ship. Two of the cruisers had been laid down in November 1938 with construction suspended in September 1939; they had been ordered scrapped but this work apparently had not yet been done at the time of Raeder’s request.

The M class conversion, designated Flight Deck Cruiser E, would have created a light carrier somewhat smaller than the American Independence class light carriers, built on hulls laid down for Cleveland-class light cruisers. The flight deck would have been about 160 meters long, a little longer than that of an American escort carrier. Between the small hull and the German practice of placing workshops and crew quarters around the edge of the hangar deck, the ship would have only carried about 10 aircraft.

The “cruiser” part of Flight Deck Cruiser E would have come from four 150mm (5.9-inch) guns mounted in the gunhouses intended for Cruiser M, one mount with two guns each placed fore and after of the starboard-side island. The tiny carrier would have also mounted eight 88mm anti-aircraft guns and 20 light automatic anti-aircraft weapons, and least according to the design sketch - actually fitting that many weapons on the small ship would have proved a difficult problem.

She would have retained the unusual combined turbine/diesel engines of Cruiser M, as well as the cruiser’s extraordinary range – though she would not have been able to stow sufficient aviation fuel and munitions to operate her aircraft for a cruise of that duration.

The limited capabilities of Flight Deck Cruiser E led to design studies for a much larger ship. Germany was in no position to build such a vessel by the time the proposals were completed in 1942, but like the Kriegsmarine’s other fantasy paper projects the work kept young naval architects engaged in “vital war work” and therefore out of the draft pool.

Large Aircraft Cruiser AII, presented in April 1942, was indeed large, weighing in at 40,000 tons’ displacement. She had a wider flight deck than the Flight Deck Cruiser, but about the same length, so pilots would not have had any easier time landing on the bigger ship. The forward part of the deck was given over to a much heavier armament, laid out like a traditional battle cruiser (and greatly resembling the Scharnhorst design).

Several variants presented different arrangement for the heavy guns: six 280mm (11-inch) guns in two triple turrets similar to those of Scharnhorst (and probably intended to be the turrets ordered removed from the damaged Gneisenau a few weeks earlier so that she could be rebuilt with larger guns) or four of them in one quadruple turret apparently based on French design sketches captured in 1940. While gun turrets from Gneisenau could be scavenged, the hull itself was off-limits for carrier conversion as the Führer had decided on her repair and re-armament.

In addition to the big guns, the ship would have eight 150mm guns in antiquated casemate mountings along her hull, and sixteen 105mm anti-aircraft guns in dual mountings along either side of the ship (Germany had no dual-purpose secondary gun available until very late in the war). She had all-diesel propulsion for a rated speed of 34 knots, and an oddly-placed port-side island. Yet despite her vastly larger size, Large Aircraft Cruiser AII only carried 23 aircraft.

Other designs presented in the spring of 1942 offered larger air groups. Large Aircraft Cruiser AIII displaced 70,000 tons, with the same armament as AII and combined turbine/diesel propulsion. All of that additional size raised her air group to 32 planes. A variation on the design brought back the quadruple turret, and another gave the ship a traditional battleship-style superstructure sited on the center line, with catapults placed at angles to either side of it.

Another design presented sometime afterwards, Large Aircraft Cruiser C, displaced 56,000 tons with six 280mm guns and an air group of 80 aircraft. Just where the guns would be sited is not clear, and the reasonable match of air group to the ship’s size implies that one or the other may be a misprint as the results are clearly not insane enough to be an actual Kriegsmarine design proposal.

R.D. Layman and Stephen McLaughlin imply that the lunacy of these designs may have been intentional, to dissuade Hitler from wasting German resources on these useless vessels. That’s a tempting theory if one looks at these designs in isolation, but in the context of the broader Plan Z the inanity is only heightened by a matter of degree: many other ships in the program were designed with almost as little contact with reality.

The Layman-McLaughlin thesis does get some traction if one considered Flight Deck Cruiser E V, a ship built on the incomplete hull of the heavy cruiser Seydlitz, then scheduled for conversion to a light aircraft carrier. This design offers a little firepower – eight 150mm guns – in exchange for a smaller air group than the “pure” carrier conversion. This one does seem intended to steer Hitler and/or Raeder toward the carrier rather than the flight-deck cruiser.

In Ships of Plan Z we’ve included one example of the one slighty reasonable design (at least when compared with those that followed), the tiny Flight Deck Cruiser E IV. She’s not a very capable ship, balancing her weak protection with a tiny air group and miniscule firepower. But on the other hand, Cruiser M was not a very good warship either, and she does give the Germans one more flight deck in the wide North Atlantic.

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Mike Bennighof is president of Avalanche Press and holds a doctorate in history from Emory University. A Fulbright Scholar and award-winning journalist, he has published over 100 books, games and articles on historical subjects. He lives in Birmingham, Alabama with his wife, three children and his dog, Leopold.