One Hundred Years of U.S. Navy Air Power (40 page)

Particularly if carriers did not use torpedo bombers, it was not clear how effective they could be against other ships. An American attempt to multiply naval aircraft within the treaty limit shows how tricky this question could be. In the run-up to the 1930 London Naval Conference, Admiral William A. Moffet of the Bureau of Aeronautics suggested building a flight-deck cruiser, which could add to the fleet's air strength without counting against carrier tonnage. At the conference, the chief American naval adviser, CNO Admiral William V. Pratt, managed to get the flight-deck cruiser into the newly limited total cruiser tonnage, of which the United States had a great deal available (the British, with whom the United States had parity, had a far larger cruiser fleet). However, when the flight-deck cruiser was tested at Newport, it failed. Its aircraft just did not have enough offensive power to balance off the reduction in cruiser guns; in duels the flight-deck cruiser was generally sunk. The
design effort, which had gone to the point of preparing plans for bids by shipbuilders, was abandoned.

The Second Vinson-Trammell Act provided enough tonnage to build a slightly improved
Yorktown
(USS
Hornet
). Her construction seems to have been pushed through by Congress against some naval staff opposition; the General Board felt that it was more urgent to build modern battleships. That did not necessarily mean that the senior navy was against carriers: one role of modern fast battleships was as escorts for carriers. Existing battleships could not keep up with carriers, and in a preradar era there was a real possibility that enemy capital ships would catch carriers—as actually happened in 1940, when the German
Scharnhorst
and
Gniesenau
sank HMS
Glorious
.

In the late 1930s there was also a fear, at least on the General Board, that the best land-based aircraft grossly outperformed modern naval aircraft, hence that carriers might be moving toward obsolescence.
²⁶
That turned out to be a temporary consequence of the level of engine development. The most powerful engines suited to fighters produced about a thousand horsepower. The British and the Germans achieved high performance effectively by wrapping airplanes like the Spitfire around these engines, providing far too little fuel for naval purposes as then understood. The U.S. Navy found that similar power applied to a fully navalized airplane like the Wildcat (F4F) produced much less performance (the Japanese solved the performance problem in the A6M Zero by adopting a very light structure, limited armament, and no armor at all). Spitfire speed was limited more by what a propeller could handle than by engine output. By 1938 the Bureau of Aeronautics understood that the coming generation of two-thousand-horsepower engines would solve the problem. Aircraft could not gain much more speed, but they could achieve maximum speed with acceptable range and other features. The resulting fighters, like the Hellcat and Corsair, were quite the equal of their land-based contemporaries. It is not clear how quickly the conclusions reached at the technical end of the Navy reached the policymakers.

U.S. naval exercises show how current fears played out. In the early 1930s, U.S. carriers regularly practiced attacking land targets, raiding Los Angeles and Pearl Harbor. In the mid-1930s the U.S. Navy adopted the high-performance (for the time) Catalina (PBY) flying boat. In line with the policy of using large numbers of flying boats (not limited by treaty) to provide an important component of naval air power, the Navy hoped that the Catalina could function not only as a scout but also as a bomber (hence the B in its designation). It seemed that Catalinas or their equivalents patrolling from Pearl Harbor could find an enemy carrier force before it got within attack range. The comment that land-based aircraft were reaching superiority meant that such detection would be fatal; the U.S. carriers stopped raiding Pearl Harbor in their exercises. This shift may have played into disbelief, in 1941, that
Japanese carriers (presumably operating under the same limitations as U.S. ships) would attack Pearl Harbor. It turned out that scouting was far more difficult than had been imagined prewar, and that carrier attacks on land targets were generally entirely practicable; but that took time to learn. Again, the perceived vulnerability of carriers was key to U.S. naval thinking.

CARRIERS FOR A TWO-OCEAN NAVY

The story of the World War II carriers began when Germany, Italy, and Japan became Axis allies in the fall of 1938. By this time the Japanese attack on China, and German pressures for territory in Europe made war seem likely. Until this time U.S. national strategy was shaped by the requirements of the most likely war, a war against Japan. Once Germany had created the Axis, it was no longer possible for the United States to contemplate a war fought entirely in the Pacific. Too, Germany and Italy now clearly threatened to penetrate South America; the United States needed the naval strength to prevent any armed assault in the Western Hemisphere. The two problems were linked in that the United States seemed to need access to southeast Asian resources in order to maintain sufficient strength to beat off any Axis attack in the Western Hemisphere. By October 1938 the OpNav War Plans Division was investigating the building program required in a “war of maximum effort,” corresponding to the World War II mobilization. In spring 1939 U.S. naval planners began to lay out the requirements of a “Two-Ocean Navy” capable of fighting simultaneous wars in the Atlantic and in the Pacific. The United States began secret staff talks with the British, who would probably also be involved in such a war.

A two-ocean Navy would clearly require more ships, including more carriers. Battleship numbers were set by the need to match all potential enemy navies in both oceans. It did not yet seem that carriers could be dominant—and neither Germany nor Italy had a large carrier fleet the United States would have to match. It is striking in retrospect that this analysis did not take into account the possibility that carrier superiority would change the rules, as when a British carrier strike sank much of the Italian battleship fleet at Taranto in November 1940—or when the Japanese did the same thing to the United States at Pearl Harbor.

The new ships were the
Essex
(CV-9) class designed during the fall of 1939. Because work began after the outbreak of war on 1 September, the previous treaty limit (23,000 tons) did not apply.
²⁷
However, it was possible to work quickly because the new carrier embodied many design features of the earlier 20,000-ton type; thus it was still somewhat limited by the defunct treaties (it displaced 27,200 tons). In drawing up characteristics for the new carrier, the General Board considered and rejected alternative proposals for relatively small carriers with armored flight decks, which would have supported many fewer aircraft. The way in which carrier flight
decks had to provide sufficient length for landing-on, parking, and taking off dramatically limited the aircraft capacity of small ships.

As conceived in January 1940, the
Essex
had a long enough flight deck to operate all four squadrons in a single operation. Compared to
Yorktown
, she had a quarter more aviation gasoline. The new carrier had new lightweight efficient high-temperature high-pressure machinery, which dramatically reduced the size of the uptakes in her island structure. Power increased from 120,000 to 150,000 SHP, more than making up for the effect of considerably increased displacement (26,500 rather than 20,000 tons; ultimately 27,200 tons). The machinery was rearranged so that it could not be knocked out by a single hit. Shrinking the island made it possible to place defensive twin 5-inch guns on the flight deck forward and aft of it (the
Yorktown
s had a few flight-deck machine guns). The new design retained four of the eight deck-edge 5-inch guns of the earlier class, those on the island side being eliminated.

Compared to previous carriers, the
Essex
class showed two great innovations. One was reliable powerful hydraulic catapults (H4 type), which by 1945 were often used to launch heavily loaded aircraft. Since rolling takeoffs were no longer necessary, a carrier could place aircraft much closer to her bow: she could operate many more aircraft. Toward the end of the war, because the Japanese used kamikazes against the U.S. fleet, carriers were provided with more fighters, and the ability to use the flight deck more fully became far more important. Catapults also made it possible to launch aircraft under worse sea conditions, because they provided positive control as the airplane ran down the deck. An unusual feature of early
Essex
-class carriers was a cross-deck catapult on the hangar deck. It was intended to launch reconnaissance aircraft even when the carrier's bow was packed with a strike that had recently landed (and had not yet been re-spotted aft). Hangar deck catapults were little used, and they were removed so that more light anti-aircraft guns could be fitted at hangar deck level. The other major change was the deck-edge elevator described above.

Much of the extra tonnage of the new carrier went into more armor. Compared to a
Yorktown, Essex
added armor on her hangar deck—which limited the effect of any explosions there (it could resist a 1,000-pound bomb). It was still impossible to provide flight-deck armor. The flight deck was flimsy, but that meant that it could quickly be repaired at sea or in a forward area—and U.S. naval strategy envisaged staging the fleet through the Western Pacific, where it might not have any sort of prepared base. Armor would be fine if it kept bombs out, but any that did penetrate would do damage that could be repaired only in a shipyard. The ships proved remarkably tough, none being sunk. By way of comparison,
Yorktown
(CV-5) and
Hornet
(CV-8) were sunk as well as the huge
Lexington
and the small
Wasp
. Much of the superiority of the new carriers could be traced to much improved damage control measures, such as changed aviation gasoline practices (
Lexington
was fatally damaged by a gasoline vapor explosion). Too, by the time the
Essex
class was
in service the United States had sufficient superiority to be able to tow badly damaged ships out of the battle area rather than scuttling them (as with
Yorktown
at Midway) to avoid their seizure by the Japanese. Even so, the survival of ships such as USS
Franklin
and USS
Bunker Hill
was remarkable, a great tribute both to their crews and to their construction. The wartime record of the
Essex
class was later used to show that carriers could survive multiple cruise missile hits, a Japanese kamikaze being quite equivalent to the later anti-ship missiles.

Late in September 1939 OpNav sketched a “two-ocean navy” including thirty-six battleships (of which the U.S. Navy already had twenty-two built and building) and eighteen carriers (of which eight had been either built, laid down, or ordered, including
Essex
). The thinking of the time shows in the proposed initial annual building program: two battleships and one carrier, plus lesser ships (it seemed necessary to expand building capacity before a larger program could be ordered). A March 1938 General Board memorandum written to help lay out a ten-year program argued that “in view of the arising questioned value of aircraft carriers relative to increasing improvement in characteristics of land planes, it is believed that if more carriers are desired they should be built as soon as possible, consequently they are listed for the next two building programs.” Congress was more positive: for 1940–1941 it authorized an additional 30,000 tons of carriers, boosting the total to 215,000 tons. The new tonnage was applied to USS
Essex
(CV-9) of the FY41 program. Because carriers were assigned a twenty-year lifetime (by treaty), replacements could not begin until 1945 (the
Lexingtons
would become overage in 1947).

In November 1939 Congress passed a 25 percent increase in underage tonnage in each category. That seemed sufficient to build four more 24,000-ton
Essex
-class carriers (CV 10–13). Because designed tonnage had risen to 26,500 tons by May 1940, the number fell to three, leaving a four-ship class (CV 9–12). These ships would bring the total U.S. carrier force to eleven. At this point CV-9 was expected to complete in January 1944, CV-10 in June 1944, CV-11 in July 1944, and CV-12 in February 1945. Once war began, the shipyards did infinitely better, so that CV-9 (
Essex
) was completed in December 1942. The others quickly followed, in April, August, and November 1943.

France collapsed in June 1940. This was far worse than the “two-ocean navy” case considered in 1938–1939, because the United States had relied on Britain and France for a degree of protection against aggression by Germany. In the worst case the Royal Navy might fall into Axis hands. The United States could not possibly, it seemed, quickly build a fleet sufficient for offensive action in both oceans, but the General Board recommended starting at once on a fleet sufficient to maintain a defense in one ocean while mounting an offensive in the other. The recommended fleet gives an idea of the value then being placed on carriers: thirty-two battleships and fifteen carriers. Of these, however, the existing fifteen U.S. battleships were slow
and obsolescent, whereas all seven existing carriers were fast, modern ships. To meet the desired force level the General Board asked for another four carriers (CV 13–16), which would more than double the existing carrier force. The “Two-Ocean Navy” Act Congress passed envisaged a 70 percent increase in tonnage, equivalent to seven rather than four more carriers (the Navy did not need 70 percent more battleships, so much of the newly available battleship tonnage went into cruisers and destroyers—but not into carriers). Thus by December 1940 ten new carriers (CV 10–19) were under contract beyond
Essex
.