One Hundred Years of U.S. Navy Air Power

by Smith, Douglas V.

  By July 1921 the U.S. government was planning an international naval disarmament conference in Washington, which it held in November 1921. Apparently an influential senator (William Borah, R-ID) had demanded that the government seek an international agreement to end new naval construction before asking for money to complete the 1916 ships, and the Harding administration called the conference to forestall him. Many in Congress saw the conference as an opportunity to discard the expensive 1916 program. It seemed at the time that a capital shipbuilding competition was beginning among Britain, Japan, and the United States; it was widely imagined that the pre-1914 competition between Germany and Britain had helped cause the ruinous war recently ended (this idea now seems much less convincing). The main outcome of the conference was that the United States achieved naval parity, at least in capital ships, with Great Britain—in the past by far the dominant naval power. Japan was forced to accept a limit of 60 percent of U.S. or British tonnage, creating the famous 5:5:3 ratio. The Washington Naval Treaty that emerged from the conference dominated warship design—including carrier design—during the interwar period. In July 1921 one senator linked naval disarmament with a proposal to convert two of the incomplete battle cruisers into carriers.10 They were the closest the Navy could hope to come to the General Board’s preferred 35,000-tonner.

  Although they were new, the Washington Treaty treated carriers as capital ships, subject to the same 5:5:3 ratio as battleships. With preliminary designs for the converted battle cruisers in hand, the U.S. delegation secured a clause that allowed any of the three main signatories to convert two existing or incomplete capital ships into carriers, displacing up to 33,000 tons (battleships could displace up to 35,000).11 New carriers could displace up to 27,000 tons, a figure based on a contemporary U.S. design study. The U.S. position was to seek enough tonnage for the two battle cruisers plus Langley. The British, who were already using carriers, believed that a fleet needed a substantial number. This position in turn reflected the British belief that no single carrier could operate very many aircraft (see below). The effect of this British concern was to set a much higher total, 135,000 tons, than might have been expected for what many still imagined was an entirely experimental type of ship (the battleship total was set at 525,000 tons). Clauses in the treaty allowed replacement of existing ships after a set lifetime, but the British were allowed an escape clause: their World War I ships were classed as experimental and hence could be replaced much earlier. However post-1918 Royal Navy could never convince the British government to do so.

  The U.S. delegation was determined to obtain enough tonnage to complete the two battle cruisers. Chief Constructor David W. Taylor knew that preliminary designs for the huge converted battle cruisers would require about 36,000 tons, and it was impossible to demand more for a carrier than for a battleship (when the U.S. delegation tried, the British demanded that the limit be raised to 45,000 tons, which would have allowed them to complete some entirely new ships that would have outclassed all existing ones). On the other hand, the treaty allowed navies to rebuild existing battleships (to reduce incentives to build new ones) to improve their protection against the threats of bombs and underwater weapons, which had not really been taken into account when most existing ships had been built. Navies were allowed 3,000 tons per ship for this purpose. The U.S. interpretation of the treaty treated the two huge ex–battle cruisers as existing ships that could be so modified (several attempts to redesign them without the extra 3,000 tons showed just how necessary that tonnage was). Like the United States, Japan converted two new capital ships, as yet incomplete, into large carriers. Unfortunately for the Royal Navy, in 1921 it had just ordered new ships, but none had yet been laid down, so it had to make do with conversions of two much smaller “large light cruisers,” HMS Courageous and HMS Glorious, plus further reconstruction of HMS Furious.

  The treaty provided the U.S. Navy with the two largest carriers in the world, USS Lexington and USS Saratoga. A distinctive U.S. way of operating carriers (see below) gave the nation the largest Carrier Air Wings in the world, and experience with those air wings showed the U.S. Navy what carriers could do. Second, the generous tonnage allowance encouraged the U.S. Navy to build a substantial carrier force during the interwar period. The designs of this time became the basis for the fleet carriers the U.S. Navy built during World War II.

  While U.S. naval aviation developed in the decade after World War I, U.S. naval planners worked out the details of a war against the most likely future enemy, Japan, code-named “Orange.” By 1929 it was clear that an Orange war would involve large numbers of airplanes, far beyond what the treaty-limited carrier force could possibly accommodate. The Orange war plan therefore envisaged converting merchant ships into auxiliary carriers (XCV, the X indicating conversion) as well as into numerous other types of auxiliaries. Conversion plans were drawn up for several large U.S. liners. The relatively anemic U.S. Merchant Marine of the time offered too few suitable ships (even the largest liners were relatively slow), and the conversion plan was eventually dropped because the plans envisaged would have taken far too long to carry out. In 1936 a new U.S. Maritime Commission was created to revive the U.S. merchant fleet, and specifically to build fast merchant ships that might be suited to wartime conversion. Within a few years it had designed a passenger ship (P4-P) specifically suited to carrier conversion (it was never built). The Maritime Commission did develop the C3 freighter, which became the basis for World War II escort carriers, and it created the industrial base that built, among many other things, fifty Casablanca-class escort carriers during World War II. Merchant ship conversion was considered by the other two carrier navies, the Royal Navy and the Imperial Japanese Navy. Only the Japanese took it really seriously, subsidizing merchant ships specifically intended for wartime conversion—including some that became World War II carriers.

  The Lexington design was undoubtedly influenced by the British designs for their first two fleet carriers, HMS Eagle and HMS Hermes. In both ships the flight deck was integral with the hull, the hangar a cavity scooped out of the hull. The hangar was a closed space without side openings. That in itself limited hangar capacity for a hull of a given size (estimated capacity was seventy-two aircraft).12 Unlike the British ships, the U.S. carrier was given a powerful surface gun battery, eight 8-inch guns in four twin mounts. They were intended to defend her in the event she was caught by cruisers, but they consumed valuable flight-deck space (and the ships’ flight decks narrowed forward because they were blended into the hull). These were the most powerful guns allowed on board carriers by the Washington Treaty, and presumably they were considered essential because the treaty encouraged creation of a new kind of 8-inch gun cruiser. The initial sketch showed two turrets forward of the island and two more alongside the flight deck aft, but ultimately the ship had all four turrets on deck, and her flight deck was widened aft. The new Bureau of Aeronautics resisted the idea of this kind of encroachment from the beginning of the new carrier design. No other navy placed heavy guns on the flight deck; the bureau did succeed in killing the proposed torpedo tubes, on the grounds that the ship’s own torpedo bombers should suffice, and also succeeded in moving the 5-inch guns down to cuts in the flight deck rather than, as planned, on the flight deck itself. On the eve of World War II modernization plans included removal of the heavy gun battery, which was to be replaced by twin 5-inch dual-purpose guns (Lexington was sunk after her 8-inch guns were removed but before new flight-deck guns could be installed). Because the ships were expected to operate not only wheeled aircraft but the floatplanes otherwise launched by cruiser and battleship catapults, the design included a flywheel-powered catapult (one forward and one aft in the original design, only the bow one as built). This catapult was not intended to launch the ship’s wheeled aircraft (the British later adopted much the same approach). Catapults became important only later.

  The USS Saratoga (CV-3), recovering her aircraft, June 1935.

  REEVES’ CARRIER RE
VOLUTION

  The U.S. Navy of that era was very fortunate in that it tested its ideas on the game floor of the Naval War College, that is, not only at sea (more generally, the War College acted as the Navy’s think tank). Although such experimentation might seem the obvious way to develop new technology, the U.S. Navy seems to have been unusual in emphasizing it. The ships and aircraft involved could adopt whatever characteristics seemed relevant to future warfare. Officers could see what the aircraft of the future (rather than existing relatively primitive ones) might contribute to a naval battle. The games showed how important it was to mass aircraft (and also to launch them quickly, as a carrier might easily be put out of action by enemy attack). Captain (later Admiral) Harris Laning encouraged games involving large numbers of aircraft, far beyond what the existing carrier Langley could support, and emphasized the need to put the enemy’s carriers out of action at the outset. Captain (later Admiral) Joseph M. Reeves took this lesson with him when he assumed command of the aircraft of the Battle Force, which at the time meant mainly the few assigned to Langley.13 He had attended the War College in 1923–1924, became head of its tactics department in 1924, and on 1 June 1925 was assigned to the Bureau of Aeronautics. A few days later he went to Pensacola for the aviation observer’s course, which would fit him to command an air unit. Once graduated, he was assigned in September 1925 to command Battle Fleet Aircraft Squadrons as senior officer aboard the prototype carrier, Langley. Reeves saw Langley as the essential school in which U.S. naval air doctrine would be created. She first went to sea, with Reeves aboard, in December 1925.

  It was assumed that the aircraft capacity of any one carrier was limited because the Royal Navy, the most experienced carrier navy by far, had reached that conclusion after trials in 1918. Just as aircraft landing ashore would taxi off the runway before the next aircraft landed, the British stowed their aircraft in the carrier’s hangar upon landing. That made for lengthy intervals between landings. It also meant that a ship’s aircraft capacity was set by her hangar capacity, which in early carriers was very limited. Hence the British insistence on a large total carrier tonnage at Washington in 1921.

  Coming from the War College, Reeves understood that he had to pack more air power into the small Langley. He found that airplanes did not need the whole deck on which to land. Instead of being stowed below upon landing, they could simply be wheeled forward, protected from landing aircraft by a wire barrier. In this way aircraft could be taken on board much more quickly.14 Once all were aboard, they could be moved aft and be massed at the after end of the flight deck. They could take off again, en masse, to attack. In contrast to the British, in this view the hangar was mainly a workshop; many aircraft would spend very little time under cover. By March 1926 it was understood that an American carrier deck should be divided into three areas, all working simultaneously: a landing-on area aft, equipped with arresting gear; a rearming and servicing area roughly amidships, to prepare a follow-on strike; and a launch area forward. It became clear that launching tempo depended on landing tempo; if the landing interval was too long, aircraft would run out of fuel. Reeves therefore pressed his pilots to fly more precisely so that landings would be much quicker and much safer, with innovations like a circular formation feeding aircraft continuously into the landing area and like the division of the flight deck (aircraft handling) crew into teams with distinctively colored uniforms. As aircraft performance improved, it became impossible to operate the flight deck continuously. Instead, carriers spotted all or most of their strike aircraft aft, launched them, and spotted them forward (in front of the barrier) when they returned. After all had landed, they were all re-spotted back aft for a new strike. This change probably occurred in the mid-1930s.

  The use of one end of the ship for landing, the other for taking off, and the area between for parking and servicing, encouraged BuAer to suggest in 1926 that future carriers should be truly double-ended, for greater flexibility, with arresting gear and catapults at both ends. The Yorktowns of the late 1930s had arrester wires at both ends, with four barriers between them, but they had only a limited ability to sustain high speed running astern. In theory this made it possible for the ship to launch fighters or scouts even when the bow was full of strike aircraft just recovered and not yet re-spotted. Similarly, scouts might be recovered over the bow when the usual landing area was full of aircraft spotted for a strike. The World War II Essex class did have the ability to sustain high astern speed. A few surviving photographs show Essex-class carriers recovering aircraft over their bows, running astern. Another means of launching when most aircraft were spotted forward was a hangar deck catapult firing athwartships, a feature of the Ranger and later designs (though not installed on board many of these ships).

  Langley ultimately operated about four times as many airplanes as she had before Reeves arrived. From a ship design point of view, Reeves’ innovation meant that carrier operating capacity depended on the size of the flight deck and the length of deck airplanes needed to take off, rather than on the capacity of the hangar. It took some years for that to become obvious, because at first the assumption was that aircraft would be placed on the flight deck only when they were about to fly, or had landed. Probably the U.S. Navy took time to realize that aircraft could survive prolonged exposure there (it helped that the U.S. Navy operated mainly in temperate climates). Neither the British nor the Japanese (who began their naval air arm with British tutelage) ever understood this use of the flight deck, to the extent that even many decades later a senior British warship designer asked this author how it was that American carriers packed in so many more aircraft with less hangar space than did British carriers. The radical difference in operating practice was why numbers of aircraft at the Battle of Midway were fairly equal, even though the Japanese had six carriers to the U.S. Navy’s three.

  It may have been key that Reeves was not a pilot (he had trained as an observer); he understood what naval aviation could provide to the fleet, but he was not viscerally aware of just how dangerous carrier operation could be. To a pilot, it must have seemed unnatural to land an airplane into a mass of parked aircraft, relying on arresting gear and a barrier to keep from crashing into them. The British based their own estimates of carrier capacity (and their operating practices) on pilots’ views, because from 1 April 1918 on, their naval aircraft were operated by the new Royal Air Force. It is striking that the U.S. Navy often discussed—and accepted—the dangers of carrier operation, to the point that films of the classic era of carrier aviation seem incomplete without numerous crashes, many of them fatal. A memoir of interwar British carrier aviation was titled It’s Really Quite Safe, You Know. American observers were surprised by how casual British carrier landings seemed. U.S. landings were highly disciplined because they had to be so precise to engage the arresting gear in the right place (for many years the Royal Navy did not even use arresting gear). About 1930 the Royal Navy finally realized that it could operate a lot more aircraft by adopting U.S.-style deck parking. Nothing happened, because by that time the British Air Ministry feared that total British aircraft numbers would be limited by a future disarmament treaty; it did not want the Royal Navy to consume too much of that limited pie.

  Reeves’ operating technique shaped U.S. carrier aircraft. Carriers had catapults, but they were not considered very effective, so aircraft generally rolled down the flight deck to take off. Carrier capacity was determined by how far aircraft had to roll, because when the carrier launched all her aircraft for a strike the first airplane had to start out from just ahead of a mass of aircraft parked on the after part of the flight deck. Generally the requirement was that the airplane be able to take off in four hundred feet in the twenty-knot wind the ship could generate. It turned out to be quite acceptable until the end of World War II. Among other things, it meant that a ship with a relatively short deck could operate modern carrier aircraft as long as she was assigned a small enough air group that they left the necessary four hundred feet of deck.
That became very important during World War II.

  Given U.S. operating practice, carrier deck capacity could be set either by the required landing area plus the spotting area used by aircraft once they landed, or by spotting area plus the takeoff space needed by the first airplane. Between 1930 and 1939 takeoff run increased by 93 percent—but average carrier deck length increased by only 7 percent. Higher aircraft performance required higher wing loading, which in turn increased the takeoff run—which was one reason catapults became increasingly important during World War II. They were disliked because they greatly increased the interval between launches, but without catapults the need to match increasingly powerful land-based aircraft would make it more and more difficult to operate enough aircraft on a carrier; ultimately airplanes might need the whole flight deck merely to take off. That is what happened as jets entered service; they became usable only as powerful enough catapults entered service.

  Landing space depended on the airplane’s stall speed, which rose by about 13.5 percent in 1930–1939. High lift devices were applied from 1935 on, and this reduced stall speed and enabled a slower approach speed. To the landing area had to be added the run-out of the arresting wire, which absorbed the energy of the landing airplane (in 1939 this distance was 40 to 100 feet). The overall length devoted to landing was about 315 feet, including the run-out. If this length were not increased as landing speed increased, then the rate of barrier crashes would rise; the rate for 1937 was 1.11 per 1,000, cut to 0.96 in 1938 but increased to 1.23 in 1939. Since carriers could not grow to keep pace with the higher performance airplanes introduced during and after World War II, it was not surprising that crashes became more common—that the existing form of flight deck was perceived as more and more dangerous. The number of aircraft that could park on deck depended on the area per airplane, which until 1936 fell as biplanes became more compact, with higher wing loading, but then grew as monoplanes entered service.15