Country of origin:

Japan

Description:

Medium range heavy bomber

Power Plant:

Two 1,092 kw (1,450 hp) Nakajima Ha-109 fourteen-cylinder two-row air-cooled radial engines

Specifications:

Armament:

One 20 mm cannon manually operated in dorsal position; one 7.7 mm (0.303 in) machine gun in ventral, beam, nose and tail positions. Max internal bomb load 1,000 kg (2,205 lb)

History:

The Nakajima Ki.49 series known as the Donryu (Storm Dragon) was designed to supercede the Mitsubishi Ki.21 bomber, which was then just entering Japanese Army service. The prototype (c/n 4901) was first flown in August 1939. Built as a mid-wing monoplane with a crew of eight, it was powered by 709 kw (950 hp) Nakajima Ha-5 KAI radial engines driving Hamilton Standard two-pitch three-blade propellers. Designed by N Itokawa and T Koyama, attention was paid to handling, and a mid mounted wing of low aspect-ratio was selected to obtain good stability and manoeuvrability at low altitudes, the wing having six self-sealing fuel tanks. Fowler-type flaps were adopted and extended from the fuselage to the ailerons. Armament was a 20 mm cannon on the port side and a machine gun in the tail turret. The bomb-bay extended almost the length of the wing center-section.

The 2nd and 3rd prototypes and first seven production aircraft differed in having 932 kw (1,250 hp) Nakajima Ha-41 radial engines driving constant-speed propellers and this model became known as the Army Type 100 Heavy Bomber Model I Donryu (Ki.49-1). Ten aircraft were involved in the trials programme, during which there were changes in armament, crew protection and seating arrangements. A production order was placed in March 1941. Deliveries to operational units commenced in July 1942, the first being the 61st Sentai. Other units which operated the ‘Helen’, as it became known to the Allies, fought in Manchuria, Malaya, Burma, Rabaul, throughout northern New Guinea, and later the Philippines. Units involved were Heavy Bomber Sentais 7, 61, 62, 743 and 95, each having a nominal strength of between 27 and 37 aircraft.

The type was initially deployed to Japanese Army operations in China but it soon became involved in operations in the Pacific Theatre, particularly in New Guinea and New Britain where a Sentai equipped with the type was based. The first bombing mission over Australia by Japanese forces was a raid on Darwin, NT on 19 February 1942, but at this time the ‘Helen’ was not in service in the area. The first operation against northern Australia, and Darwin in particular, by the Donryu was on 20 June 1943, the 61st Sentai based in the Celebes, with a force of 18 bombers, escorted by Nakajima Ki.43 ‘Oscars’ attacking Australian targets.

However, the type suffered badly at the hands of opposing fighter units, this raid being costly to the attacking forces, and the ‘Helen’ was not used to make any further attacks on the Australian mainland, although further operations were carried out in New Guinea and in other parts of the Pacific. At least one was shot down near Darwin and fell into Australian hands, being inspected by technical staff. Another almost intact example was discovered at one of the Cape Gloucester airstrips on western New Britain when the island was invaded by US Marines in December 1943, and similarly was the subject of a technical inspection.

Between 28 March and 27 April 1941 there were nine attacks in the Darwin area, and anti-aircraft guns and American pilots in Curtiss P-40 Kittyhawks accounted for 17 bombers and 11 fighters destroyed, for the loss of 8 Kittyhawks. Damage was not extensive. Darwin was not attacked in May but in June 1941 concentrated attacks were made, three of these raids being mounted by 27 bombers with an escort of 18 to 20 fighters, the main target being the Darwin aerodrome. During this month 13 enemy aircraft were shot down for the loss of nine fighters. Japanese attacks on Darwin re-commenced on 25 July, with five attacks being made by small bomber formations unescorted, further attacks being made on 30 July, on this occasion six Zeros and two bombers being destroyed.

Crews considered the Donryu to be underpowered and development proceeded to overcome difficulties in this regard, Nakajima designing the Ki.58, an escort fighter variant of the Ki.49, powered by two Nakajima Ha-109 engines, three prototypes being completed. This had better armour protection and armament increased to five flexible 20 mm Ho-1 cannon and three 12.7 mm (0.50 in) Ho-103 machine guns. However, this model was soon abandoned when the Nakajimi Ki.43 was found to be able to escort the bombers.

In 1942 the prototype of the Ki.49-II was flown with Nakajima Ha-109 engines and this had improved armour and self-sealing fuel tanks. It subsequently entered production as the Ki.49-IIa, and later as the Ki.49-IIb, the latter having three of the 7.7 mm (0.303 in) machine guns replaced by 12.7 mm (0.5 in) machine guns. However, it was found the performance was still inadequate when it met Allied fighters and development lead to the Ki.49-III with 1,805 kw (2,420 hp) Nakajima Ha-117 engines. It was hoped this engine would eventually produce 2,089 kw (2,800 hp) but there were many teething problems with the engine which were never eradicated and only six prototypes of this model had been completed when production concluded in December 1944.

Some Donryus were fitted with electronic and magnetic detection gear for the anti-submarine role, and others were operated as troop transports. Others were modified in the field as night fighters, operating in pairs, one fitted with a searchlight in the nose and known as the ‘hunter’ and a second aircraft had a 75 mm cannon in the fuselage as the ‘killer’. However, they were not particularly successful in this role. Eventually they were used in the kamikaze role, the armament being removed and the crew reduced to two, carrying 1,600 kg (3,527 lb). The type was eventually replaced in mid 1944 by the Mitsubishi Type 4 Heavy Bomber, known as the Ki.67 ‘Peggy’ but this new type was not operated in this region as, by the time of its introduction, Japanese forces were being pushed back across the Pacific.

The Donryu was built by Nakajima (769), Tachikawa (50), and a few by Mansyu in Harbin, Manchuria. None is known to survive in a museum but the wrecks of a few have been located where they were abandoned at Alexishafen, New Guinea, including serial 3220.