Based upon experience in satisfying the needs of the Japanese Navy, Herbert Smith undertook a new design for a carrier attack bomber, reverting to the biplane configuration. The first of this type (Company designation 2MT1) was completed in 1923, and a year later was accepted as the Navy Type 13 Carrier Attack Aircraft, of which several versions were produced.
The first production version was powered by a 450 hp Napier Lion W-type water-cooled engine, and designated Type 13-1 carrier Attack Aircraft (B1M1). It was of wooden construction with fabric covering. It had a fixed wide-track undercarriage which allowed the following military load to be carried; one 800 kg (1,764 lb) 457 mm (18 in) torpedo or two 240 kg (529 lb) bombs. The aircraft had a crew of two, consisting of pilot and observer, both in open cockpits. The observer had a 7.7 mm (0.303 in Lewis machine-gun in the rear cockpit. Most aircraft also had a fixed synchronised forward-firing Vickers machine-gun operated by the pilot. All could be equipped with either wheel undercarriage or twin floats to meet different mission requirements.
Within the Type 13 Carrier Attack Series was the Model 2MT4 Ohtori (Wild Goose) Type Reconnaissance Seaplane (3 built). This was a twin-float long-range reconnaissance aircraft completed in 1925. it was evaluated by the Navy at Kasumigara along with the Nakajima-Breguet 19A.2B and the Kawasaki-Dornier Do D, but none of the three were accepted by Navy.
As an experiment the 2MT5 Tora (Tiger) Type Carrier Aircraft was fitted with the 450 hp Mitsubishi Type Hi (Hispano-Suiza) water-cooled engine instead of the Napier Lion. Completed on 4 February, 1926, it recorded a maximum speed of 122 kts and a rate of climb of 17 min to 3,000 m (9,843 ft) during tests flights at Kagimigahara. On a closed-course distance test from Kasumigaura and return with stop-overs, Mitsubishi pilot Sumitoshi Nakao flew this aircraft 3,108 km () from 25 May to 31 May, 1926. This model became the prototype of the Type 13-2 Carrier Attack Aircraft (B1M2) although production aircraft were built as three-seaters.
The Model 3MT2 was also powered by the Type Hi engine had Farman reduction gear fitted to improve take-off and climb performance. The propeller was either a four-blade or a larger diameter two-blade unit to absorb the added power. This model was officially accepted by the Navy as the Type 13-3 Carrier Attack Aircraft (B1M3) in January 1931 and served as an all-round combat aircraft for the Japanese Navy. it was relied upon as the main strike force aircraft until the early stages of the Sino-Japanese Conflict. It was never considered inferior to its Western counterparts and was therefore highly respected within the operational units. Many remained in operational service until 1938, some having been donated as Hokuku-go aircraft.
When the Shanghai Incident broke out in January 1932 the carriers Akagi and Hosho were in Chinese waters and the Imperial Japanese Navy's 1st Air Wing deployed 32 Type 13 Carrier Attack Aircraft against targets in and around Shanghai. On 5 February, 1932 two Mitsubishi Type 13s escorted by three Nakajima Type 3 Carrier Fighters were engaged in aerial combat with some Chinese Vought Corsairs. While on 22 February, 1932, over Suchou, three Mitsubishi Type 13-3s, escorted by three Nakajima Type 3-2 (A1N2) Carrier Fighters from the Kaga were attacked by a single Chinese Boeing Model 218 (export version of the Boeing P-12E), flown by the American volunteer pilot Robert Short. The Boeing was shot down by the combined fire of the six Japanese aircraft. The unit commander Lieut Susumu Kotani, was killed and his radio-operator/gunner, was badly injured. However, Sub-Lieut Yoshiro Sakinaga flew the aircraft back to its base at Shanghai.
Manufacturer: Mitsubishi Nainenki Seizo KK (Mitsubishi Internal Combustion Engine Co Ltd).
Type: Single-engined Carrier Attack Bomber.
Crew (2 or 3): Pilot and radio-operator/gunner in open cockpits.
Powerplant: (Type 13 -1) One 450 hp Napier Lion twelve-cylinder W water-cooled engine with reduction gearing, driving a two-blade wooden propeller, (Type 13-2) one 450 hp Mitsubishi Type Hi (Hispano-Suiza) twelve-cylinder vee water-cooled direct drive engine, driving a two-blade wooden propeller.
Armament: (Type 13-1) twin rear-firing 7.7 mm (0.303 in) machine-guns flexibly mounted in open dorsal position, (Type 13-2) two fixed forward-firing 7.7 mm (0.303 in) machine-guns and twin flexibly mounted 7.7 mm (0.303 in) machine-guns in open dorsal position. Bomb-load: One 800 kg (1,764 lb) 457 mm (18-in) Torpedo, or two 240 kg (529 lb) bombs.
Dimensions: Span 14.766 m (48 ft 5 1/2 in); length (Type 13-1) 9.773 m (32 ft 1 in), (Type 13-2) 10.06 m (33 ft); height (Type 13 -1) 3.505 m (11 ft 6 in), (Type 13-2) 3.52 m (11 ft 6 1/2 in); wing area (Type 13 -1) 59 sq m (635 sq ft), (Type 13-2) 57 sq m (613.5 sq ft).
Weights: Empty (Type13-1) 1,442 kg (3,179 lb), (Type 13-2) 1,765 kg (3,891 lb); loaded (Type 13-1) 2,697 kg (5,945.7 lb), (Type 13-2) 2,850 kg (6,283 lb); wing loading (Type 13-1) 45.6 kg/sq m (9,339 lb/sq ft), (Type 13-2) 50 kg/sq m (10,241 lb/sq ft); power loading (Type 13-1) 6 kg/hp (13.227 lb/hp), (Type 13-2) 6.33 kg/hp (13.955 lb/hp).
Performance: Maximum speed (Type 13-1) 113 kt (130 mph), (Type 13-2) 105 kt (121 mph); landing speed (Type 13-2) 75 kt (86 mph); climb to (Type 13-2) 3,000 m (9,843 ft) in 20 min; service ceiling (Type 13-1) 4,500 m (14,763 ft); endurance (Type 13-1) 2.6 hr, (Type 13-2) 5 hr.
Production: A total of 402 Type 13s were built as follows:
Mitsubishi Nainenki Seizo KK as follows:
197 - 2MT1-3 (Type 13-1) from 1923.
1 - 2MT4 Ohtori - 1925
1 - 2MT5 Tora - 1926
115 - 2MT5 (Type 13 -2) from 1926
88 - 3MT2 (Type 13-3) from 1930
Hiro Kaigun Koshol as follows:
Approx 40 - Type 13-3