U.S. Navy Aircraft Development, 1922–1945 Part II

During the late 1920s flying boat operations in the Navy began to stagnate as increasing emphasis and funding was devoted to aircraft carrier development. Though over the course of the ensuing years new designs appeared, they were, in the words of Rear Admiral A. W. Johnson in a paper on the development and use of patrol planes, “of no useful purpose except for training and utility services.” In contrast to the seagoing force that had demonstrated so much the potential of the flying boat in fleet operations in the immediate postwar years, Johnson, who commanded Aircraft, Base Force, noted that “patrol plane squadrons became in reality a shore based force,” with cruising reports of seaplane tenders during the late 1920s and early 1930s proof of the diminished employment of flying boats in fleet operations. Even the Consolidated Aircraft Company’s P2Y, which achieved fame when it equipped Patrol VP Squadron 10F in a record-setting non-stop flight between California and Pearl Harbor, Hawaii, in January 1934, had limitations: “[It] must operate from sheltered harbors, and can do nothing in the way of scouting and bombing that cannot be as equally well done by large land planes operating from established shore bases equipped with good flying fields.” Yet, landplanes for distant overwater flights were the exclusive domain of the Army Air Corps, a 1931 agreement between Army Chief of Staff General Douglas MacArthur and Chief of Naval Operations Admiral William V. Pratt preventing the Navy from operating long-range land-based aircraft.

Johnson’s comments came at a critical juncture for both the development of flying boats and the strategic requirements for their employment in the event of war. By the early 1930s, those officers working on War Plan Orange, the constantly evolving American strategy in the event of war with Japan, had begun to more appreciate the role of air power in a fleet engagement. With ships able to engage at greater distances, advance scouting, particularly in the open expanses of the Central Pacific, could prove a deciding factor between victory and defeat.35 For proponents of patrol aviation, this tactical and strategic requirement for flying boats coincided with the introduction of a plane that represented a tremendous advance in flying boat technology—the PBY Catalina.

With a maze of struts and wires between wings limiting the performance of earlier biplane designs, Consolidated Aircraft Company engineers drew up a flying boat built around a high-mounted parasol wing with minimal struts necessary because of internal bracing; this reduced drag, as did wing floats that retracted once airborne to form wingtips. Despite a gross weight that exceeded that of the P2Y it replaced, the PBY boasted a top speed nearly 40 miles per hour faster than that of the P2Y. Deliveries of the PBY began in 1936, and two years later fourteen Navy patrol squadrons operated the type. “I feel very strongly that when the PBY’s [sic] come into service, the Fleet will begin to realize the potentialities of VP’s [sic] [patrol planes],” wrote Rear Admiral Ernest J. King on the eve of the aircraft’s delivery, “and will begin to demand their services.”

Performance in fleet exercises validated the PBY’s capabilities as a long-range scout. Comments on patrol plane activities in Fleet Problem XVIII held in early 1937 concluded that they were capable of locating an enemy force within a five hundred- to one thousand-mile radius of their bases, night tracking, and high-altitude bombing. “Your patrol planes have certainly changed the whole picture in regard to tactics and even strategy,” Captain W. R. Furlong of the Bureau of Ordnance wrote King. Such was the range that the newly arrived Catalinas could reach; planners of future war games would have to “put the brakes on the patrol planes to keep them from finding out everything long before we could get the information from the cruisers and other scouts.”

The capabilities of the PBY, coupled with fatal crashes, spelled the end of the use of rigid airships as long-range scouts, an idea long championed by Rear Admiral William A. Moffett, the first chief of the Bureau of Aeronautics. However, non-rigid airships, notably of the K-class would prove effective in long-range antisubmarine patrols during World War II.

Not as clear in discussions about patrol aviation was the advisability of using flying boats in a bombing role. There was indeed a precedent in the practice, F-5Ls having participated in the famous 1921 bombing tests against captured German warships and stricken U.S. Navy vessels. In 1934, while serving as Chief of the Bureau of Aeronautics, Rear Admiral Ernest J. King had suggested that flying boats could serve as a first strike weapon in an engagement at sea, their attacks preceding those of carrier planes and surface forces. Correspondence between Captain John Hoover and Admiral Joseph Mason Reeves, the latter Commander in Chief, United States Fleet, the following year illuminated the problems with flying boats operating in this capacity. Umpires in fleet exercises determined that patrol planes would incur heavy losses and inflict insignificant damage to capital ships when used in the strike role, with Hoover pointing to the fact that the slow speeds and low service ceilings of patrol planes then in operation (the Consolidated P2Y and Martin PM) made attacks by them “suicidal.” “The way to utilize patrol planes for attacking must by re-studied from a practical viewpoint.” The introduction of the PBY Catalina (“PB” being the Navy designation for patrol bomber), which incorporated a nose compartment for a bombardier and provision to carry the Norden bombsight, offered more promise when it came to patrol bombing operations. However, as the author of the foremost study of planning for the war against Japan has noted, by 1940 the notion of operating flying boats as patrol bombers had been discounted. Yet, wartime necessity would awaken interest in flying boat offensive operations for the PBY and other flying boat designs of the 1930s, including the PBM Mariner and PB2Y Coronado.

By mid-1941, the year in which naval aviation entered the world’s second global war, the Secretary of the Navy could report a net increase of 82 percent over the previous fiscal year in the number of service aircraft on hand in the Navy’s inventory. His annual report noted emphasis being placed on development of dive-bombing and fighting aircraft of greater power, which was “vindicated in the service reports received from belligerents abroad.” Other technical adaptations based on wartime observations included such equipment as self-sealing fuel tanks and improved armor and firepower. “With the present international situation,” the secretary concluded, “it is imperative that all construction work on ships, aircraft and bases be kept at the highest possible tempo in order that the prospective two-ocean Navy become a reality at the earliest possible date.” The sudden events of the morning of 7 December 1941 shifted this tempo into previously unimagined levels, the events that occurred between that day and September 1945 representing the ultimate test for the technology and tactics that evolved during the previous two decades.

“When war comes,” Captain John Hoover wrote in 1935, “we will have just what is on hand at the time, not planes on the drafting board or projected.” For naval aviation, the combat aircraft flying from carrier decks, fleet anchorages, and airfields when war came had entered service between 1936 and 1940. Fortunately, however, the planes that eventually would replace or complement them were far removed from the drafting board. The prototype of the F6F Hellcat made its first flight just months after the Pearl Harbor attack, while the XF4U-1 Corsair had already demonstrated speeds of over four hundred mph during test flights in 1940. Similarly, prototypes of the SB2C Helldiver and TBF Avenger had already taken to the air by the time the United States entered World War II. And with the coming of war, the mobilization of industry translated into rapid transformation of prototypes into production versions of airplanes ready for combat, with American factories turning out an average of 170 airplanes per day from 1942 to 1945.

How did these airplanes fare in the crucible of combat? A telling statistic is found in an examination of air-to-air combat: During the period 1 September 1944–15 August 1945, the zenith of naval aviation power in the Pacific, in engagements with enemy aircraft, a total of 218 naval carrier–based and land-based fighters were lost in aerial combat, while Navy and Marine Corps FM Wildcat, F6F Hellcat, and F4U Corsair fighters destroyed 4,937 enemy fighters and bombers. Even during the period 1942–1943, when naval aviators flew the F4F Wildcat, which in comparison to the heralded Japanese Zero had an advantage only in its defensive armor and self-sealing fuel tanks, carrier-based and land-based Wildcat pilots splashed 905 enemy fighters and bombers. This came at a cost of 178 Wildcats destroyed and 83 damaged. Comparing the two eras, in all the action sorties flown by naval aircraft during 1942, 5 percent ended in the loss of the aircraft. In 1945, less than one-eighth of 1 percent of all action sorties resulted in a combat loss. While direct comparisons are not possible with other classes of aircraft, a look at the total number of sorties flown against land and ship targets by year is revealing. In the first two years of the war, 19,701 sorties were directed against ship and shore, a figure that for the years 1944–1945 jumped to 239,386!

A key reason for this increase was aircraft development. The carrier Enterprise (CV-6), at sea when the Japanese attacked Pearl Harbor, had none of the same aircraft types on board when she operated off Japan in 1945. The F4U Corsair and F6F Hellcat by that time in the war boasted better top speeds, rate of climb, and performance at altitude than the most advanced versions of the Japanese navy’s Zero fighter. Similarly, the SB2C Helldiver and TBF/TBM Avenger, particularly once technical maladies were corrected in the former, proved to be more than comparable to the aircraft operated by the Japanese in the torpedo and bombing roles. In addition, Japanese aircraft to a great extent suffered from deficiencies in their armor protection, making them more susceptible to being shot down by Allied aircraft and antiaircraft gunners. Even though the Japanese did produce some very capable aircraft as the war progressed—among them the all-metal Yokosuka D4Y Suisei bomber that had a top speed comparable to many fighters and the Kawanishi N1K1-J/N1K5-J Shiden and Shiden Kai fighter, which in the hands of an experienced pilot could be more than a match for an Allied fighter—they appeared in too few numbers to have much effect on the outcome of the war. In addition, due to increasing Allied superiority in material, the successful campaign against Japanese merchant and combat ships, and the increasing conquest of territory, Japanese planes were at a strategic and tactical disadvantage before they even left the ground.

There is more to the story behind the statistics. First, sortie rates and the number of enemy aircraft destroyed rose in direct proportion to the growth of U.S. naval aviation. In 1941 there were 1,774 combat aircraft on hand in the U.S. Navy. By 1945 that figure had grown to 29,125. When the Japanese attacked Pearl Harbor, the Navy had a total of seven fleet carriers and one escort carrier in commission. Between that time and the end of the war, the Navy commissioned 102 flattops of all classes. Then there was the human factor. Imperial Japanese Navy and Army pilots generally remained in combat squadrons until they were killed or suffered wounds that rendered them unable to fly, this policy of attrition steadily reducing the quality of enemy pilots faced as the war progressed. This was apparent as early as late 1942, a Report of Action of Fighting Squadron (VF) 10 in November 1942 noting that the “ability of the enemy VF [fighter] pilots encountered in the vicinity of Guadalcanal is considered to be much inferior to the pilots encountered earlier in the war.” In contrast, experienced U.S. naval aviators rotated in and out of combat squadrons. For example, Lieutenant Tom Provost, designated a naval aviator during the late 1930s, flew fighting planes from the carrier Enterprise (CV-6) during the early months of World War II, including service at the Battle of Midway. His next tour was as a flight instructor, imparting knowledge to fledgling pilots before returning to the fleet in 1944 and 1945 to fly F6F Hellcat fighters off an Essex-class carrier. These naval aviators were well led and well trained. Fighter squadron commanders during the early months of the war, notably Lieutenant Commanders John S. Thach and James Flatley, proved adept at developing tactics to maximize the advantages of their aircraft over those of the enemy while the U.S. Navy’s longtime emphasis on teaching deflection shooting paid dividends in actual combat. The same imparting of lessons learned was standard in other types of squadrons as tactics developed throughout the war.

During World War II, were U.S. Navy aircraft employed in a manner envisioned during the interwar years and how did the ever-changing tactical environment affect the operations of naval aircraft? The answers to these questions provide an important framework in which to assess the history of aircraft development between 1922 and 1945.

Much prewar discussion centered on how naval aircraft could be most effective in a fleet engagement, and concerns expressed at that time about the vulnerability of torpedo planes proved well founded, with carrier-based torpedo squadrons at Midway suffering grievous losses. Despite the fact that even as late as May 1945, experienced carrier task force commander Vice Admiral Marc A. Mitscher still considered the torpedo “the major weapon for use against surface ships,” the number of torpedoes dropped at sea decreased as the war progressed. For carrier-based aircraft and land-based aircraft, during the first year of the war torpedoes accounted for 73 percent and 94 percent, respectively, of the total ordnance expended on shipping by weight. By 1945, those figures had dropped to 16 percent and 0 percent, respectively, and throughout the war only 1,460 torpedoes were dropped by naval aircraft. Factors contributing to these low numbers included the problematic aerial torpedoes in the U.S. inventory early in the war and the focus of carrier strikes in the war’s latter months being increasingly centered on hitting land targets. During 1945 the total tonnage of bombs dropped on land targets by Navy and Marine Corps aircraft was 41,555 as compared to just 4,261 tons of ordnance dropped on ships of all types during the same period.

Dive-bombing lived up to expectations as a tactic that could influence the outcome of a sea battle, a fact demonstrated in dramatic fashion in the sinking of four Japanese carriers at the Battle of Midway. However, as evidenced by the statistic above, as the war moved ever closer to the Japanese home islands, targets for carrier-based dive-bombers were increasingly located ashore rather than afloat, with planes attacking harbor areas, transportation networks, and enemy airfields. It was in the bombing mission that wartime experience shuffled the prewar and early war composition of carrier air groups. Scouting squadrons, which in 1942 were equipped with the same airplane—the SBD Dauntless—as bombing squadrons on board carriers, were eliminated from carrier air groups by 1943. In addition, torpedo planes and fighters increasingly assumed some of the ground attack mission, the latter reawakening the fighter versus fighter bomber debate of the 1930s. Commanders had no choice but to use fighters in the bombing role during 1944 and 1945 when the advent of the kamikazes necessitated that the number of fighter planes in a carrier air group be increased dramatically. By war’s end, their numbers were double that of the combined number of torpedo and scout-bombers. In the fighter-bomber role, naval single-engine fighters from land and ship logged a comparable number of ground attack missions as that of airplanes designed as bombers. However, on these missions they expended primarily rockets and machine gun ammunition. The SBD Dauntless, SB2C Helldiver, and TBF/TBM Avenger proved the mainstay of the bombing mission, the latter aircraft proving to be one of the most versatile naval aircraft of the entire war. The dive-bombers carried 34 percent of all naval aviation’s bomb tonnage, while Avengers delivered 32 percent of the bomb tonnage and launched 29 percent of all rockets.

The employment of fighters in the bombing role was central to the debate about the composition of carrier air groups, the subject of much discussion as the war drew to a close. A 1944 survey of carrier division commanders on the subject revealed a consensus that the majority of airplanes on deck should be fighters, the problematic SB2C Helldiver perhaps influencing calls for fighters to assume a ground attack role in addition to the air-to-air mission. Vice Admiral Mitscher preferred dive-bombers over fighter bombers, telling Captain Seldon Spangler, who was on an inspection tour of the Pacific in 1945, that dive-bombers, even given the inadequacies of the SB2C, were better than the F4U Corsair in the bombing role. Wrote Spangler, “He thought it would be most desirable to get down to two airplane types aboard carriers, one to be the best fighter we can build, the other to be a high performance torpedo dive bomber.” Rear Admiral Gerald F. Bogan concurred to some degree. Although favoring the intensification of dive-bombing for fighting planes, he wrote “Do not emasculate the VF plane.” Interestingly, in production were two airframes that met Mitscher’s requirements, the BT2D (later AD) Skyraider, which combined the torpedo and bombing missions into one attack mission, and a pure fighter in the form of the F8F Bearcat. Interestingly, the F4U Corsair, which, after some technical problems were solved, became an excellent carrier plane and served for years after World War II on the basis of its capabilities as a fighter bomber.

“The Fleet is well satisfied with PBY-5A airplanes for use at Guadalcanal for night reconnaissance, bombing, torpedo attack, mining, etc.,” read an 28 April 1943, report to the Director of Material in the Bureau of Aeronautics. “They are not using these airplanes in the daytime except in bad visibility.” This concise summary of operations in the first part of the Pacific War reveals that in their decision to remove the flying boat from consideration as a long-range daylight bomber, prewar officers were correct about the platform’s capabilities. Action in the war’s early weeks proved the vulnerability of the lumbering PBYs to enemy fighters, with four of six PBYs of VP Patrol Squadron 101 shot down on a 27 December 1941, raid on Jolo in the central Philippines. However, under the cover of darkness, the aircraft proved highly effective in the ground attack mission. As prewar exercises demonstrated, PBYs performed well as long-range scouts, most notably in their locating elements of the Japanese fleet at Midway. Their ability to patrol wide expanses of ocean also made them effective as antisubmarine platforms against German U-boats as well as very capable search and rescue aircraft.

What could not have been foreseen during the 1930s in light of the division of roles and missions between the armed services was the successful operation of long-range multi-engine landplanes in naval aviation. As noted above, the Pratt-MacArthur agreement had given the Army Air Corps exclusive use of long-range land-based bombers to fill their role in coast defense, but with flying boats limited in daylight bombing, the Navy began pressing for the ability to operate multi-engine bombers from land bases. In July 1942 the Sea Service reached an agreement with the Army Air Forces (re-designation of Army Air Corps in 1941) to divert some production B-24 Liberators to the Navy for use as patrol bombers. The first of these airplanes, designated PB4Y- 1s, were delivered to the Navy in August, and the following year, with its focus on the strategic bombing campaigns in Europe and the Pacific, the Army Air Forces relinquished its role in antisubmarine warfare. Other aircraft eventually joined the PB4Y-1 in the patrol bombing role in both the European and Pacific theaters, including a modified Liberator designated the PB4Y-2 Privateer, the PBJ (Army Air Forces B-25) Mitchell, and the PV Ventura/Harpoon.

While the Army Air Forces employed their bombers in primarily in horizontal attacks, which were also carried out by Navy and Marine Corps medium bombers, many Navy crews specialized in low-level bombing, oftentimes dropping on enemy shipping at masthead level. A review of 870 PB4Y attacks against shipping revealed that over 40 percent of them resulted in hits. In addition, they were credited with downing over three hundred enemy planes, the PB4Ys being heavily armed with machine guns. Marine PBJs proved the workhorse of land-based patrol bombers, flying more than half of all action sorties flown. All told, patrol bombers, while flying just 6 percent of naval aviation’s action sorties, dropped 12 percent of all bomb tonnage delivered on targets during World War II.

A number of other operations involving naval aircraft are worthy of discussion in drawing conclusions about the development of naval aircraft through World War II. Radar-equipped aircraft made tremendous strides in operations after dark during World War II, completing some 5,800 action sorties from carriers and land bases. From a total of only 76 attacks (air-to-ground and air-to-air) against enemy targets in 1942, naval aviation night operations grew to include 2,654 nocturnal attacks in 1944. The PBYs would not have been able to have as much of an offensive impact as they did without their night attack capability. Carrier aircraft, despite fears about tying carriers to beachheads in support of amphibious operations, achieved a great deal of success in providing close air support to assault forces, primarily flying from escort carriers. Naval aircraft, including carrier-based ones, proved that they could neutralize land-based air power, with fighter sweeps focusing on enemy airfields on island chains and the Japanese homeland serving the purpose of striking potential attackers at their source. “Pilots must be impressed with the double profit feature of destruction of enemy aircraft,” read a June 1945 memorandum on target selection for Task Force 38 carriers operating off Japan. “Pilots must understand the principles involved in executing a blanket attack. The Blanket Operation is NOT a defensive assignment. It is a strike against air strength.” Finally, in the field of weapons development, the advances like electronic countermeasures equipment to thwart enemy radar and the introduction of high-velocity aircraft rockets (HVAR) made carrier aircraft more capable platforms, the latter yielding positive results particularly in close air support against enemy defensive positions.

In a speech delivered during the 1920s, Admiral William S. Sims remarked, “One of the outstanding lessons of the overseas problems played each year is that to advance in a hostile zone, the fleet must carry with it an air force that will assure, beyond a doubt, command of the air. This means not only superiority to enemy fleet aircraft, but also to his fleet and shore-based aircraft combined.” This statement reflected the essence of naval air power, and it can be argued that during the interwar years all aspects of aircraft development, from design to tactics, supported the drive of naval aviation advocates toward a fleet that reflected this vision. By 1945, at the end of the greatest war the world has ever known, a triumphant flight of hundreds of carrier planes over the battleship Missouri (BB 63) as the instrument of surrender was being signed on her deck was proof that the vision had been realized.