IXO Models IXJ200622 Japanese Aichi B7A2 Ryusei "Grace" Attack Aircraft - 752 Kalgan Kokutai, April 1945 (1:72 Scale)
"We have resolved to endure the unendurable and suffer what is insufferable."
- Japanese Emperor Hirohito speaking to the Japanese people after the atomic bombings, August 1945
Dubbed the Allied code-name "Grace," the B7A2 Ryusei was the largest and heaviest Japanese carrier-based attack aircraft to fly in World War II. The Grace flew on shapely wings bent near midspan to provide clearance for a large propeller that spanned 3.5 m (11 ft). The Grace flew and handled as well as it looked, but the B7A2 never played a significant role in the Japanese war effort. Development began on this aircraft in 1941. That year Japanese Navy planners issued ambitious specifications describing a new attack bomber that, if built and selected for service, would eventually replace two different models already operational, the Nakajima B6N JILL torpedo bomber and the Yokosuka D4Y "Judy" dive-bomber.
The new design had to accommodate two 250 kg (551 lb) or six 60 kg (132 lb) bombs within an enclosed bomb bay, or a single 800 kg (1,764 lb) torpedo suspended beneath the fuselage. The navy also specified these additional requirements: a heavy defensive armament consisting of two 20 mm cannons mounted in the wings and a flexible 13 mm machine gun mounted in the aft cockpit, a top speed of 570 kph (354 mph), a maximum range of 3,220 km (2,000 mi), and maneuverability that matched the Zero fighter.
Navy officials understood that this large, high-performance aircraft demanded a powerful engine. They instructed Aichi to use the Nakajima Homare 11 engine, a power plant in the 1,800 to 2,200 hp-class. This radial engine was still in development but it was comparable to the very successful Pratt & Whitney R-2800. Aichi Chief Engineer, Norio Ozaki, and his assistants, Morishige Mori and Yasushiro Ozawa, selected a mid-fuselage wing position for the new bomber. This layout, and the wing's gull-shaped kink, was necessary to provide adequate ground clearance for the under-slung torpedo. Aichi completed the first prototype in May 1942 but engine problems and other difficulties kept the firm from commencing production until April 1944. At this time, Aichi also changed to the improved Homare 12 engine.
Aichi and the navy set up two assembly lines, one at Aichi's home factory at Funakata, and the other at the Naval Air Arsenal at Omura. Unfortunately for the Japanese Navy, the production rate never really shifted into high gear. After building the airplane for about a year, production halted at the main factory after of a major earthquake destroyed the plant in May 1945. Aichi had produced only 80 production aircraft (plus nine prototypes). The Arsenal produced another 25 aircraft, for a total delivery of only 105 bombers. To compound the problem of fielding the Grace, the US Navy had all but eliminated the Japanese carriers during the Battles of Midway, the Philippine Sea, and Leyte Gulf. With no sea base from which to operate, the handful of B7A2s delivered to navy units flew only from land bases. Most of these airplanes were destroyed in kamikaze attacks during the last months of the war. Sold Out!
Wingspan: 7.75 inches
Length: 6.25 inches
Release Date: February 2007
Historical Account: "Long Lance" - The Type 93 was a 610mm (24-inch) diameter torpedo used by the Imperial Japanese Navy during WWII. Called the "Long Lance" by US sailors (a nickname attributed to Samuel E. Morison, a historian who spent much of the war in the Pacific theater), it was the most advanced torpedo in the world at the time.
The Type 93 was quietly developed in Japan in the 1930s. At the time, the most powerful potential enemy of the Japanese Navy was the US Navy's Pacific Fleet, which contained several battleships. The US doctrine called for the US battle line to fight its way across the Pacific Ocean, supported by cruisers and destroyers, to destroy the enemy. The Japanese planned to counter this fleet by whittling it down in a succession of long-range nightfighting actions as the fleet crossed the Pacific.
The only naval weapon of the time that could sink powerful, heavily armed and armored battleships at long range was the torpedo. Consequently, the Japanese Navy invested heavily in developing torpedoes, and particularly heavy torpedoes to replace their existing 24-inch conventional 8th year type torpedo. Their research focused on using compressed oxygen instead of compressed air for its propulsion oxidizer, feeding this into an otherwise normal wet-heater engine. Air is only about 21% oxygen, so a torpedo using compressed oxygen instead of air would hold about 5 times as much oxidizer in the same size tank. This meant that the torpedo could travel further and faster. Additionally the uncombusted air, principally nitrogen, bubbled to the surface and left a trail pointing back at the launcher. With oxygen, the gas was almost completely burned and left an almost invisible bubble trail.
Conversely, compressed oxygen is more dangerous to handle and it required lengthy testing and experimentation for it to be possible to use operationally. Finally it was discovered that by starting the engine with compressed air and gradually switching over to pure oxygen, engineers were able to overcome the uncontrollable explosion that hampered its development. To conceal the use of oxygen, the oxygen tank was named Secondary Air Tank and was first deployed in 1935.