The Emperor’s Sword:
The U.S. Flying Deck Cruiser

By Randy York
October 2023

In 1931, the U.S. Navy was actively designing the flying deck cruiser. The restrictions of the Washington Naval Treaty on fortifying Pacific bases meant that the Navy knew that aviation would be ship borne during the cross Pacific trek of War Plan Orange. Seeking a way to bring aviation into the fleet at a faster pace than the limited funding for new carrier construction allowed and to circumvent the restriction on total allowed carrier tonnage in the treaty, the Navy came up with a cruiser with significant aviation capability.

At the time, Lexington (CV-2) and Saratoga (CV-3) were new to the fleet after protracted conversion times caused in large part by limited funding. There was still debate by the theorists on whether carriers should be large like Lady Lex and Sara or smaller. Ranger (CV-4), built small for the maximum possible air fleet, was still in the future to prove larger is better. Yorktown (CV-5) and Enterprise (CV-6) would be larger than Ranger with Wasp (CV-7) built small to use up the remaining allowed carrier tonnage.

December 1939 drawing of a proposed flight deck cruiser.


The Washington Naval Treaty of 1922 restricted U.S. Navy total carrier tonnage to 135,000 tons and defined a carrier as a vessel designed for the specific and exclusive purpose of carrying aircraft and between 10,000 and 27,000 tons. Article IX also included a provision for two carrier conversions not exceeding 33,000 tons (U.S. Lexington, Saratoga. Japanese Akagi, Kaga. No other signatory utilized the provision, though the British converted three smaller battle cruisers).

Article XIX provided for status quo in the Pacific and no new fortifications or naval bases nor increases to naval facilities for the repair and maintenance of naval forces. The U.S. Navy was most affected because the cross Pacific trek would not have a fleet base. U.S. Navy began the Mobile Base Project and to design/modify ships with longer cruising ranges in the next decade, but that is another story. To understand this article, when a seaplane arrived in the Philippines it had to be based on a seaplane tender and not use land facilities. If the seaplane used land facilities, Japan could file a protest. The Navy could not get seaplane tenders or anything else built in the frugal administrations of the 1920s.

Rear Adm. William A. Moffett, head of the Bureau of Aeronautics 1921-33 and a great proponent of naval aviation, began to push for a cruiser that had aviation power to get more airplanes into the fleet by 1928. At British insistence there were no restrictions on the number of cruisers in the treaty. Moffett also advocated using large dirigibles as airborne aircraft carriers.

The risk of losing fleet air power concentrated in a few large decks concerned Navy planners: in the 1929 Fleet Problem IX Sara was “lost.” The cruiser, being smaller, cheaper and more numerous, would get aviation spread onto more decks. Also important, cruisers might actually get funded. Moffett through the Navy secretary requested five small carriers and only one received funding. Moffett planned to ask for seven flying deck cruisers to be built by 1936.

First designated as Light Aircraft Carrier (CLV) for Naval War College war games, the flying deck cruiser ended up designated as CF because the Chief of Naval Operations the felt that CLV would be confusing when compared to Light Aircraft Carrier (CVL). It was since CLV is understood today as a light cruiser with significant fixed wing capability. An apt description but CF is the historical designation. (Also, calling this a light carrier rather than a cruiser would seem to be a good way to bring protests from the other signers of the treaties.)

At the London Naval Conference of 1930 the U.S. had clauses added to the London Treaty to allow for the flying deck cruiser. During late 1930 the various Navy bureaus presented design studies. The main contention was whether the cruiser would be a flush deck design or have an island superstructure. The superstructure won since fire control needed to be mounted on something and without it the ship looked like a carrier.

By June 1931 the design was a 637-foot, 11,580-ton cruiser with nine 6-inch guns forward in triple turrets and eight 5”/25 along the sides. Two of the 5-inch were designated as anti-aircraft guns. Even this was considered overkill by some. A faction favored deleting all the 5-inch entirely since the 0.50 caliber machine guns would be more effective against attacking dive bombers! A folding funnel and the first angled flight deck (an innovation that would wait until well after World War II) were included in the design. The teeth of the ship would have been the 350 foot flight deck with 24 aircraft; a squadron of fighters and a squadron of observation/dive bombers. With 32-knot speed this design gives a new meaning to “commerce raiding cruiser.” The hunting cruiser would find itself the hunted instead as the CF turns into the wind. Add one of these to a World War II cruiser force with two squadrons of fighters and it has combat air patrol. Some of these in the Asiatic Fleet in 1941 would have made things interesting.

The final Navy plan, styled CF-2 and dated January 1940.


The Great Depression was a large part of the death of the flying deck cruiser. Congress funded a ship in 1930 before the design was ready. But by 1932 new ships could not be laid down while existing ships were being laid up because there was no money. The additional time allowed the design to devolve into a real hybrid ship that could not operate aircraft very well; the angled flight deck went away replaced by a flying platform like the unsuccessful British Furious of 1917. Furthermore, Rear Admiral Moffett died in the crash of dirigible U.S.S. Akron (ZRS-4) on April 4, 1933. As part of the New Deal, funding became available for large scale new construction in 1933. Carriers and cruisers were built instead of the flying deck cruiser (not a bad idea).

The closest thing the Navy would get was the Independence class carrier conversions from cruiser hulls during World War II — ships not recommended for a surface action.

The flying deck cruiser appears in the upcoming Second World War at Sea: The Emperor's Sword.

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