Aichi M6A “Seiran” (“Mountain Haze”), 631st Kokutai, (MPM Models)

TYPE: Submarine-launched attack floatplane


POWER PLANT: One Aichi “Atsuka” Type 31 liquid-cooled engine, rated at 1,400 hp

PERFORMANCE: 295 mph at 17,060 ft

COMMENT: To equip the I-400 class submarine aircraft carriers, the Imperial Japanese Navy Air service requested for an attack aircraft with a range of 1,000 mi and a speed of 345 mph. Aichi aircraft company proposed a design on the basis of the Yokosuka D4Y1 “Suisei” that Aichi was already manufacturing under license. The D4Y1 was a relatively small single-engine carrier dive bomber with exceptionally clean lines and high performance. Detailed engineering studies commenced in an effort to modify the “Suisei” for use aboard the I-400 submarines but the difficulties in doing so were eventually judged insurmountable and a completely new design was initiated.
Aichi’s final design, designated M6A1, was a two-seat, low-winged monoplane powered by an Aichi “Atsuka” engine, a license-built copy of the German Daimler-Benz DB 602  liquid-cooled engine. The aircraft was fitted with detachable twin floats to increase its versatility. If conditions permitted, these would allow the aircraft to alight next to the submarine, be recovered by crane and then re-used. The floats could be jettisoned in flight to increase performance or left off altogether for one-way missions. The “Seiran’s” wings rotated 90 degrees and folded hydraulically against the aircraft’s fuselage with the tail also folding down to allow for storage within the submarine’s 11 ft diameter cylindrical hangar.
As finalized, each I-400 class submarine had an enlarged watertight hangar capable of accommodating up to three M6A1s. The “Seirans” were to be launched from an 85 ft compressed-air catapult mounted on the forward deck. A well-trained crew of four men could roll a “Seiran” out of its hangar on a collapsible catapult carriage, attach the plane’s pontoons and have it readied for flight in approximately 7 minutes.
The first of eight prototypes was completed in October 1943, commencing flight testing in November that year. A problem with overbalance of the auxiliary wings was eventually solved by raising the height of the tail fin. Further testing was sufficiently successful for production to start in early 1944.  Owing to the reduced carrier submarine force, production of the “Seiran” was halted, with a total of 28 completed. In mid 1945, it was planned to attack the American base at Ulithi Atoll where forces, including aircraft carriers, were massing in preparation for attacks on the Japanese Home Islands. The flotilla departed Japan on 23 July 1945 and proceeded towards Ulithi. On 16 August, the flagship I-401 received a radio message from headquarters, informing them of Japans surrender and ordering them to return to Japan. All six “Seirans” on board the two submarines, having been disguised for the operation as American planes in violation of the laws of war, were catapulted into the sea with their wings and stabilizers folded (for the  submarine I-401) or pushed overboard (for the submarine I-400) to prevent capture (Ref.: 24).

de Havilland “Mosquito” F.B. XVIII, 248 SQN (Airfix)

TYPE: Fighter bomber


POWER PLANT: Two Rolls-Royce “Merlin” 21/22 or 23/24 (left/right) liquid-cooled engine, rated at 1,480 hp each

PERFORMANCE: 399 mph at 21,400 ft

COMMENT: The de Havilland DH.98 “Mosquito” was a British twin-engine shoulder-winged multi-role combat aircraft during WW II. It was one of few operational front-line aircraft of the era whose frame was constructed almost entirely of wood and was nicknamed “The Wooden Wonder”. The “Mosquito” was also known affectionately as the “Mossie” to its crews. Originally conceived as an unarmed fast bomber, the “Mosquito” was adapted to roles including low to medium-altitude daytime tactical bomber, high-altitude night bomber, pathfinder day or night fighter, fighter bomber, intruder, maritime strike aircraft, and fast phot-reconnaissance aircraft.
One fighter-bomber variant was the “Mosquito F.B. Mk XVIII” (sometimes known as the “Tse-tse”) of which one was converted from a F.B. Mk VI to serve as prototype and 17 were purpose-built. The F.B. Mk XVIII was armed with a Molins “6-pounder Class M” cannon: this was a modified QF 6-pounderanti-tank gun fitted with an auto-lader to allow both semi- or fully automatic fire. 25 rounds were carried, with the entire installation weighing 720 kg.  In addition, 410 kg of armour was added within the engine cowlings, around the nose and under the cockpit floor to protect the engines and crew from heavily armed U-boats, the intended primary target of the Mk XVIII. Two or four 7.7 mm Browning machine guns were retained in the nose and were used to “sight” the main weapon onto the target.
The Air Ministry initially suspected that this variant would not work, but tests proved otherwise. Although the gun provided the “Mosquito” with yet more anti-shipping firepower for use against U-boats, it required a steady approach run to aim and fire the gun, making its wooden construction an even greater liability, in the face of intense anti-aircraft fire. The gun was sensitive to sideward movement; an attack required a dive from 5,000 ft at a 30° angle with the turn and bank indicator on center. A move during the dive could jam the gun. The prototype was first flown on 8 June 1943.
Although only twenty-seven “Mosquito F.B. XVIII” were produced, they proved particularly efficacious against shipping, submarines and shore installations (Ref.: 24).