Historic Aircraft - The Big Flying Boat (2024)

The outstanding accomplishments during World War II of the U.S. Navy’s twin-engine flying boats—the Consolidated PBY Catalina and the Martin PBM Mariner—eclipsed the comparatively few four-engine flying boats that served the Navy during the war. Those four-engine aircraft were Consolidated PB2Y Coronados.1

In the 1930s the Navy expressed interest in four-engine, long-range patrol aircraft to support fleet operations. Prototype aircraft were ordered in 1935 and 1936, respectively the Sikorsky XPBS-1 and the Consolidated XPB2Y-1. Sikorsky—not yet developing helicopters—was a leading producer of large flying boats, while Consolidated was producing the highly successful PBY, which would serve in every theater of World War II and be produced in greater numbers than any other flying boat by any nation. Thus, both firms were well qualified in the flying boat field.

The XPBS-1 and XPB2Y-1 were similar in basic design: four-engine, high-wing, cantilever aircraft with a single tailfin. The XPB2Y-1 could carry bombs within the inner wings and on wing racks.

Both prototypes flew in 1937, the XPB2Y-1 on 17 December. Although armed and intended as a production prototype, the aircraft was not a success, suffering from control and directional stability problems. (The XPBS-1 also proved unacceptable for production.2)

Subsequently, the XPB2Y-1 was fitted with twin circular tail fins, and the under-hull was redesigned. Trials of the modified aircraft were interrupted in late October 1938 when the XPB2Y-1 was flown to Naval Air Station Anacostia (Washington, D.C.) for an inspection of military aircraft by President Franklin D. Roosevelt. After successful trials, in early 1939 that aircraft became the flag plane for the commander, Aircraft Scouting Force; that command had operational control of all of the Navy’s patrol-plane squadrons. (The aircraft served throughout World War II as a VIP transport.)

The Navy awarded a production contract for the PB2Y-2 on 31 March 1939. Some officials questioned the production decision; Consolidated was heavily committed to PBY production, and one PB2Y cost approximately as much as three PBYs.3 The -2 variant was a greatly modified design powered by improved engines, with a modified hull, and internal wing bays for eight large bombs, and provisions for four additional bombs or two torpedoes under the wings. Twin machine-gun turrets were fitted in the nose, dorsal, and tail positions, with two waist guns and a singe “tunnel” gun provided; all were .50-caliber weapons.

Beginning in December 1940, five of six PB2Y-2s were delivered to Patrol Squadron (VP) 13 at San Diego, California. The sixth PB2Y-2 was modified to serve as prototype for the definitive PB2Y-3 variant. Among early training and trials missions with VP-13’s new aircraft, in August 1941 the squadron tested aerial refueling techniques to determine if the range of the aircraft—now called the Coronado—could be extended. Although the tests were positive, the fuel-transfer procedure was considered too complicated and time-consuming to be of operational value.

War preparations by the squadron were interrupted on 10 December 1941—three days after the Japanese surprise attack on Pearl Harbor—when two aircraft were assigned to fly Secretary of the Navy Frank Knox and his party to Hawaii to review the situation. The aircraft carrying Knox developed leaks after its fuel tanks were fully loaded. Only after several flight cancellations and delays was he flown to Pearl Harbor. That incident gave the PB2Y a bad reputation from which it would never completely recover. Subsequently, the squadron’s PB2Y-2s were employed primarily as high-priority transports between the West Coast and Hawaii and across the southern route to Australia.

VP-13 received the first PB2Y-3 for tests and operations in June 1942. The new -3 aircraft were equipped with pilot armor and self-sealing fuel tanks, while the earlier PB2Y-2 aircraft were similarly refitted.

Unfortunately, the continued improvements with no increase in engine power affected mission performance, with the overload takeoff weight of the PB2Y-3 being some 72,000 pounds. (Rocket-assist canisters often were employed for takeoff.) Aircraft trials again revealed shortcomings, requiring further modifications. Heavy bow spray was thrown through the inboard propellers during heavy-load takeoffs, causing propeller damage. Four-blade steel propellers could solve the problem, but shortages led to aircraft flying for some time with four-blade inboard and three-blade outboard propellers.

The production of PB2Y-3 variants totaled 210 aircraft. With the Navy requiring long-range transports, 29 of the first 60 aircraft off the production line were stripped of combat features and flew as PB2Y-3Rs. (They briefly had an initial designation of JRY-1.) Another ten went to Britain designated PB2Y-3B in 1943. Although intended for the Royal Air Force Coastal Command, they were employed as long-range transports with the RAF Transport Command.

The few VP squadrons that flew the PB2Y-3 in the maritime-patrol role continued to experience problems with the aircraft, mainly fuel leakage. The -3 aircraft fitted with single-stage vice two-stage supercharged engines were redesignated PB2Y-5,with transports given the suffix -5R, and evacuation aircraft -5H, and VIP transports assigned to major (flag) commands -5F. These aircraft had their gun positions faired over and were provided with side-loading hatches. The transports could carry 44 passengers and the evacuation aircraft 25 stretchers. In these specialized, noncombat roles the aircraft proved their worth, as did the “straight” PB2Y-3s that served with patrol squadrons.

PB2Y-3s flying with VP-13 and VP-102 in the Pacific proved highly effective as long-range bombers. These aircraft, some fitted with the large AN/APS-2 surface-search radar in a fairing aft of the co*ckpit, could fly 4,000-plus-mile round-trip bombing missions. The planes carried out bombing as well as minelaying operations, often flying at night. They also were credited with shooting down 11 Japanese aircraft.

The XPB2Y-3 was further modified with improved, 1,600-horsepower engines, becoming the XPB2Y-4. One PB2Y-3 was provided with further improved engines and, as the XPB2Y-6, demonstrated the potential effectiveness of the upgraded Coronado. By that time, however, long-range missions were effectively being flown by land-based PB4Y-1 (B-24) Liberator and PB4Y-2 Privateer aircraft. Similarly, the availability of the four-engine R5D (C-54) Skymaster for long-range transport missions reduced the need for seaplane transports. Thus, PB2Y production totaled 217 aircraft, including prototypes.

Two PB2Y-5H Coronados were assigned to the Coast Guard in 1944, followed by three more aircraft in 1945. The latter were antisubmarine configured, and they flew in that role as well as on search-and-rescue missions.4

With the end of the war, the heavily used PB2Ys were quickly retired, their seaplane VP role being taken by the P5M Marlins, derived from the PBM Mariner.5 The PB2Y Coronado was an important aircraft in the Pacific war, but its accomplishments paled in comparison with the smaller, twin-engine Catalina and Mariner.

1. At least a dozen other four-engine flying boats served in Navy colors during World War II: Five Boeing B-314 Clippers were impressed into Navy service (along with four into Army Air Forces service as C-98s); two Martin M-130 China Clippers; two other Martin aircraft, the XPB2M-1/XPB2M-1R and a single JRM-1 Mars; and three Sikorsky VS-44s (JR2S-1).

2. The XPBS-1 was employed as a VIP transport until 30 June 1942, when it crashed in San Francisco Bay. Admiral Chester W. Nimitz was on board at the time. The only person killed was a pilot, Tommy Roscoe.

3. See Norman Polmar, “The Best Flying Boat,” Naval History, October 2004, 14–15.

4. Records of the aircraft in Coast Guard service—PB2Y-3 variants and, reportedly, a PB2Y-5H—are not available.

5. See Norman Polmar, “Flying Boats at War,” Naval History, June 2001, 10.

Mr. Polmar, a columnist for Proceedings and Naval History, is author of the two-volume Aircraft Carriers: A History of Carrier Aviation and Its Influence on World Events (2004, 2008).

Consolidated PB2Y-3 Coronado

Type: Patrol bomber

Crew: 9

Length: 79 feet, 3 inches

Wingspan: 115 feet

Wing area: 1,780 square feet

Height: 27 feet, 6 inches

Engines: 4 Pratt & Whitney R-1830-88 Twin Wasp radial piston;

1,200 horsepower each

Max. speed: 223 mph at 20,000 feet

Armament: 8 .50-cal. machine guns M2 (4,840 rounds total)

Wing (internal): 8 1,600-pound bombs, or

8 650-pound depth charges

Wing (external): 4 1,600-pound bombs, or

4 65-pound depth charges, or

2 Mk-13-3 torpedoes

Historic Aircraft - The Big Flying Boat (2024)
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