At 5 in the morning on December 7, 1941, the Japanese heavy cruisers Chikuma and Tone catapulted one floatplane each into the sky. Their mission was to make a last weather reconnaissance around the target for the six aircraft carriers of Vice Admiral Chuichi Nagumo’s Combined Fleet. One, bearing the tail marking JI-1 and piloted by Warrant Officer Ryozo Narukawa, arrived over Lahaina in the Hawaiian Islands, discovered no enemy warships and turned back. Submarine I-1, also scouting for the Combined Fleet, spotted Narukawa at 7:30 as he flew back to Tone. The other floatplane scouted near the U.S. Navy base at Pearl Harbor before returning to Chikuma. The stage was set for carriers Akagi, Kaga, Soryu, Hiryu, Shokaku and Zuikaku to launch their attack. Although Japan had not yet declared war on the United States, the Aichi E13A1 had had its combat debut as the eyes of the Imperial fleet.
In June 1937, the Japanese navy issued a specification for a modern long-range two-seater reconnaissance floatplane, capable of being catapulted from warships. The Aichi Watch and Electric Machinery Co., Ltd., which had been specializing in floatplanes since 1920, put a design team to work on the project headed by Yoshihiro Matsuo, with technicians Morishige Mori and Yasunori Ozawa, in September 1937. In February 1938, the team unveiled two prototypes of the E12A1, a singleengine, low-wing, twin-float monoplane of all-metal construction; its elliptical wings had slotted flaps and fabric-covered control surfaces. The aircraft’s 850-hp Mitsubishi Zuisei engine drove a twoblade, constant-speed metal propeller and the two-man crew sat in tandem within an enclosed canopy.
During testing the E12A1 displayed unacceptable in-flight stability and control. The Japanese navy did not accept Nakajima’s E12N1 either, and Kawanishi declined to follow up on its design proposal. Given the potential of the E12A1’s basic design—which evidently owed something to Ernst Heinkel’s influential He-70—Matsuo’s team revamped it to come up with a more satisfactory three-seater floatplane in 1940, which was accepted as the E13A1 Type 0, Model 11. In addition to the 133 E13A1s built by Aichi’s factory in Funakata by 1942, DaiJuchi Kaigun Kokusho in Hiro built an additional 48 between 1940 and 1942, and the largest subcontractor, Kyushu Hikoki K.K. at Zashonokuma, produced 1,237 more between 1942 and 1945, for a total production run of 1,418 floatplanes.
The E13A1 had a wingspan of 47 feet 7 inches, with a wing area of 387.51 square feet, a length of 37 feet 1 inch and a height of 15 feet 5 inches. The plane weighed 5,825 pounds empty and 8,008 pounds loaded, with a maximum weight of 8,818 pounds. Its 1,080-hp Mitsubishi Kinsei 43 14-cylinder air-cooled radial engine driving a three-blade propeller gave it a top speed of 233 mph at 7,150 feet and a cruising speed of 137 mph at 6,560 feet. It could climb to 9,845 feet in 6 minutes 5 seconds and had a service ceiling of 28,640 feet. The plane’s most desirable feature was its maximum range of 1,299 miles or the ability to patrol at minimum cruising speed for up to 15 hours.
The E13A1’s original armament consisted of one flexible 7.7mm Type 92 machine gun for the observer and up to 250 kilograms (551 pounds) of externally installed ordnance—one 250-kg bomb, four 60-kg bombs or depth charges. Late in the war, some E13A1s were field-modified to carry a flexibly mounted, downward-firing 20mm Type 99 Model 1 cannon for strafing enemy ships. The only official variations on the original model, however, were the E13A1a, equipped with an improved radio, and the E13A1b, with primitive Yagi radar installed in the rear fuselage.
From the standpoint of the Japanese militarists who chose the course of war with the United States, the British Commonwealth and the Netherlands, the E13A1 entered service at just the right time. Production aircraft were allotted to the battleship Haruna and all the navy’s heavy cruisers and seaplane tenders as soon as they emerged from Aichi’s factory. Among the first cruisers to which they were assigned were Chikuma and Tone, unusual vessels with all eight of their 8- inch guns emplaced forward in four turrets, while their sterns were primarily devoted to housing, launching and recovering floatplanes. Comprising the 8th Cruiser Division, both ships spent the Pacific War’s critical early months accompanying the Combined Fleet, providing intelligence and often compensating for the Japanese lack of up-to-date radar— starting with the attack on Pearl Harbor. Prior to the carrier strike on Darwin, Australia, on February 19, 1942, Tone’s E13A1 reported weather conditions over Clarence Strait, 18 miles north of Darwin, from 5:30 a.m. until 9:55, when radio failure compelled it to return. On April 5, one of Tone’s floatplanes located British heavy cruisers Cornwall and Dorsetshire in the Bay of Bengal, leading to their subsequent destruction by carrier planes.
Ironically, one E13A1 crew dropped the ball during its most critical mission of the war. At 7:28 a.m. on June 4, while Nagumo’s carrier planes were bombing the American base at Midway Atoll, floatplane No. 4 from Tone reported: “Sight what appears to be ten enemy surface ships, in position bearing 010 degrees distance 240 miles from Midway course 150 degrees, speed over 20 knots.” Almost an hour later, at 8:20, the Japanese were readying for another attack on Midway when plane No. 4 radioed that the American naval force probably included aircraft carriers. That belated intelligence led Nagumo to order his Nakajima B5N2s immediately rearmed with torpedoes for a strike against the American flattops, leaving his carrier decks cluttered with ordnance and vulnerable to any bombs that might fall upon them. And, in spite of a murderous defense by the Combined Fleets’ Mitsubishi A6M2 Zero fighters, enough Douglas SBD-3 dive bombers did get through to set fatal fires aboard Akagi, Kaga and Soryu.
Meanwhile, Chikuma’s and Tone’s E13A1s and older Nakajima E8N2 biplanes continued to scout the Americans. Tone’s E13A1 No. 4 returned after losing several pursuing Grumman F4F-4 Wildcat fighters in the clouds. After locating Task Force 17 and shadowing it for 31⁄2 hours, Chikuma’s E13A1 No. 5, piloted by Petty Officer 3rd Class Hisashi Hara, was caught and shot down in flames by Lt. j.g. Rhonald J. Hoyle and Machinist William H. Warren of carrier Enterprise’s fighter squadron VF-6. The only other Japanese floatplane loss at Midway was E8N2 No. 3 from Tone, shot down by Machinists Howell M. Sumrall and Julius A. Achten, also of Enterprise’s VF-6.
During the struggle for Guadalcanal, Chikuma and Tone launched seven floatplanes during the Battle of the Eastern Solomons on August 24, 1942. At 2 p.m. Chikuma’s E13A1 No. 2 discovered the U.S. Navy’s presence, but was shot down by carrier fighters. Messages from Chikuma’s E13A1 No. 5 and a Mitsubishi F1M2 floatplane from battleship Hiei were not picked up, but at 2:30 Chikuma’s floatplane finally reported Task Force 16’s location. In consequence, planes from Shokaku and Zuikaku damaged Enterprise but failed to sink it—poor recompense for the loss of light carrier Ryujo to an American carrier strike. American defenses against “snoopers” improved during the campaign—two of the four floatplanes dispatched by Tone during the Battle of Santa Cruz on October 26 were shot down.
Code-named “Jake” by the Allies, the E13A1 became a common sight aboard Japanese seaplane tenders, or at coastal and island bases from the Gulf of Thailand to the Gilbert Islands. Besides scouting Allied fleet and aerial activity, the long-legged floatplane occasionally bared its modest fangs during antisubmarine patrols. On February 16, 1943, the U.S. Navy submarine Amberjack, then credited with sending three Japanese ships and 28,600 tons to the bottom, was attacked off New Britain by an E13A1 from the Rabaul-based 958th Kokutai (naval air group). Although the plane caused no significant damage, it reported the sub’s position, and later that morning Amberjack came under attack from the torpedo boat Hiyodori and subchaser No. 18. The submarine dived, but one or more of the nine depth charges dropped by its pursuers scored, destroying Amberjack and killing all 74 hands aboard it. E13A1s of the 958th Kokutai may also have sunk the submarine Grampus in the same area in response to its torpedoing the aircraft ferry Keiyo Maru on February 19.
Submarine Grenadier had sunk six ships totaling 40,700 tons when it surfaced 10 miles west of Lem Voalan Strait, northwest of Penang, at dawn on April 21. Its captain, Commander John A. Fitzgerald, spotted two Japanese ships that turned away, but he decided to wait and see if they would change course again and come back. Fifteen minutes later, however, Grenadier sighted—and was spotted by— a patrolling E13A1 of the Penang-based 936th Kokutai. Grenadier crash-dived and Fitzgerald was heard to remark, “We ought to be safe now, as we are between 120 and 130 feet.” Just then, depth charges dropped by the plane exploded close by, causing the sub to heel over 15 to 20 degrees, knocking out its power and lights, and starting a fire in the maneuvering room. Grenadier descended to 267 feet, where its crew spent an agonizing 13 hours making repairs. Even though they finally succeeded in regaining the surface, Grenadier had no propulsion, save for one slowly turning shaft.
Fitzgerald considered the option of drifting toward the Malay coast—and even of rigging sails. Any such hopes were dashed on the 22nd, however, when the Americans sighted an 1,800-ton Japanese cargo ship and an escort vessel—as well as a torpedo bomber. Deciding against submerging with no power, Fitzgerald burned classified documents while crewmen manned machine guns topside. They succeeded in damaging the enemy plane, which veered off for home while its torpedo fell 200 yards away and exploded. The oncoming ships, however, left the Americans no recourse but to scuttle and abandon their boat. Eight officers and 49 enlisted men were rescued by the merchantmen, but four died in the course of their brutal captivity in Penang.
Although too poorly armed to do so by day, E13A1s hunted and bombed U.S. Navy patrol torpedo boats in the Solomons by night, at one point being credited with reducing the PT-boats’ effectiveness by 50 percent. At 1:30 a.m. on October 15, 1943, Leading Airmen Takashi Takayama of the 938th Kokutai operating from Poporang made two bombing runs against four PT-boats. His bombs missed, however, and at 200 meters’ altitude his fuel tank was hit and set ablaze by machine gun fire. Managing to land, Takayama swam clear of his plane, but his two crewmen did not survive and he was too burned and exhausted to resist capture by one of the PT-boats. Even late in the war, E13A1s operating from outposts bypassed in the U.S. Navy’s “island hopping” campaign occasionally made nocturnal nuisance bombing raids on Manus, Green Island and other American bases.
As a resurgent U.S. Navy took the offensive in 1944, its carrier pilots occasionally encountered Jakes shadowing their task forces from various island bases. Whenever such sightings occurred and an E13A1 was unable to lose itself in cloud cover, the outcome was seldom in doubt— its lone 7.7mm machine gun was no match for the six .50-caliber guns of a Grumman F6F Hellcat or Vought F4U Corsair. When nine Japanese carriers confronted 16 American flattops in the Battle of the Philippine Sea on June 19, 1944, they were assisted by 43 floatplanes. Only a dozen were left when the Japanese, who had lost carriers Taiho, Shokaku and Hiyo and most of their aircraft, withdrew in defeat on June 20. As the Americans invaded Okinawa in April 1945, Jakes with their crews reduced to two or even one joined other Japanese aircraft in final desperate kamikaze missions against the U.S. fleet.
The E13A1’s combat use was not exclusively Japanese. In 1942, Japan shipped three to Thailand, which assigned them to its 1st Naval Squadron based at Sattahip and Chalong Bay. The E13A1s, then the most up-to-date aircraft in the Royal Thai Navy, proved ideal for long patrols over the Gulf of Thailand, sometimes in support of Japanese operations. Besides naval escort and search and rescue missions, the Thai floatplanes were used to spot and report low-altitude bombing and minelaying sorties by Consolidated B-24 Liberators of the Tenth Air Force off the Thai coast. After Thai warships and coastal gunners brought down a Liberator, the Japanese gratefully presented three more E13A1s to them in June 1944. One of the floatplanes was subsequently destroyed in Chalong Bay during an Allied raid on the night of July 24-25. The remaining five survived the war, but by informal agreement with the victorious Allies they—and all other Japanese warplanes—were withdrawn from Thai service.
Japan’s surrender on September 2, 1945, was not quite the end of the Aichi floatplane’s martial career. Eight E13A1s that had been left in Indochina by the departing Japanese were commandeered and restored to serviceability by the returning French. Operated by Escadrille 8S of the Aéronautique Navale, they patrolled the coast and the Gulf of Tonkin for Viet Minh arms smugglers and saboteurs from late 1945 to 1947, when newer aircraft and helicopters became available.
Advanced when it entered service, the E13A1 was the most produced and most important Japanese reconnaissance floatplane of World War II. Few, if any, entirely intact examples exist today, but parts of E13E1s, many recovered from watery graves, turn up in museums or military bases throughout Japan and the Pacific.
Originally published in the April 2006 issue of World War II. To subscribe, click here.