Navy Type 95 Landbased Attack Aircraft (G2H1) (Navy Experimental 7-Shi Attack Aircraft)
History:
Spoiler
The Washington Treaty of 1922 imposed limits on the tonnage of capital ships for the US Navy, the Royal Navy, and the Japanese Navy. Similarly, the London Treaty of 1930 set restrictions on the number of smaller vessels, including aircraft carriers and cruisers.
Recognizing the potential of Navy land-based bombers to bolster fleet operations, Japanese Navy planners initiated the development of the Hiro Navy Type 95 Land-based Attack Aircraft. This new requirement for enhanced air power led Rear Admiral Isoroku Yamamoto, then Chief of the Engineering Department at Naval Air Headquarters, to call for a long-range land-based attack bomber capable of flying over 2000 nautical miles and carrying a two-ton bomb load, beginning in 1932.
The Hiro Arsenal was chosen for this project due to its extensive experience in designing large, all-metal aircraft. The chief designer, Lieutenant Commander Jun Okamura, who had previously led the Type 91 Flying-boat project, took charge. This land-based bomber quickly became the primary focus at Hiro Arsenal, shifting attention away from the flying-boat development previously underway. Initially designated the Hirosho 7-Shi Special Attack Aircraft, it was later known as the G2H1.
The bomber’s structure featured a large wing with a traditional Wagner diagonal tension-field design, a slender monocoque fuselage, and twin fins and rudders similar to those on the final Type 90-1 Flying-boats. The ailerons were of the Junkers double-wing type. An innovative feature of the armament was a retractable cylindrical belly gun turret, a design element later incorporated into the early versions of the Mitsubishi Navy Type 96 Land-based Attack Aircraft, known to the Allies as “Nell” during the Pacific War.
Powering the bomber were two Type 94 water-cooled engines, each producing 900 to 1,180 horsepower, the most powerful available at that time. These engines, developed by the Hiro Arsenal as scaled-up versions of the 600hp Type 90 engine, were believed to provide performance comparable to that of three- or four-engine aircraft of the era.
Although the airframe dimensions, wing area, and empty weight were almost identical to the Type 90-1 Flying-boat, the G2H1 boasted a range and payload nearly 50% greater. It was the largest land-based aircraft in the Navy at the time, second only to the Army’s Type 92 Heavy Bomber (Ki.20) of Junkers-G 38 design, and the first large aircraft specifically designed as a land-based attack bomber.
With a wingspan of 103 feet, 11 1/4 inches, slightly larger than the four-engine Boeing B-17 Flying Fortress, the first G2H1 prototype was completed on April 29, 1933, at the Hiro Arsenal and transported by ship to Yokosuka. Its first flight took place in mid-May 1933, witnessed by Rear Admiral Yamamoto, the originator of the bomber concept for the Navy. The flight was piloted by Lieutenant Commanders Shinnosuke Muneyuki and Toshihiko Odahara of the Flight Experiment Group at Yokosuka Kokutai. After a brief pass over the field, the aircraft was flown to Kasumigaura Air Base for testing.
As flight evaluations continued, the aircraft demonstrated excellent performance as the Navy’s largest land-based plane at the time. However, several issues arose, including tail vibrations due to the fuselage’s light structure, aileron flutter, and engine unreliability. One aircraft was lost during testing due to aileron and tail flutter, resulting in a ditching in Tokyo Bay. Despite these problems, design corrections were made, leading to the aircraft’s acceptance for production.
In June 1936, the Navy officially accepted the aircraft as the Type 95 Land-based Attack Aircraft, alongside the Type 96 Land-based Attack Aircraft (G3M1), known as “Nell.” To avoid confusion between the two, the G3M1 was referred to as the Type 96 Chu-ko (Medium Attack) or simply “Chuko,” while the G2H was called the Type 95 Dai-ko (Large Attack) or “Dai-ko.”
After six G2H bombers were produced at Hiro Arsenal, production was transferred to Mitsubishi. However, the Navy soon requested a focus on the smaller G3M, leading to the curtailment of the G2H due to maintenance difficulties with the Type 94 engines and the aircraft’s poor low-speed handling. As a result, Mitsubishi produced only two additional units.
On April 1, 1936, the remaining G2H1s (a total of eight were built) were assigned to the newly formed Kisarazu Kokutai but were considered second-line aircraft compared to the superior G3Ms. Heavy losses of G3Ms over Nanjing in August 1937 led to the deployment of the G2Hs to an airfield on Saishuto Island (now Cheju Do, off the southern coast of South Korea). However, during the journey, one G2H crashed near Sagami Bay for unknown reasons.
Once deployed, the G2Hs, part of the 1st Combined Kokutai, participated in missions supporting ground forces in the Shanghai area, beginning on September 30, 1937, under the command of Lieutenant Motokazu Mihara. They continued to carry out attacks on nine major combat areas, sustaining damage from anti-aircraft fire but with no aircraft lost. However, disaster struck on October 24, 1937, when one aircraft caught fire while its engines were being started and soon exploded. The fire spread to the other G2Hs, each loaded with three 250kg, five 60kg and five 50kg bombs, exploding successively until four aircraft were destroyed and the fifth badly damaged.
Thus, the Hiro Arsenal concluded its impressive history of all-metal aircraft development. The technological advancements it achieved, building upon imported Rohrbach designs, were passed on to Mitsubishi. This legacy contributed to the success of the 9-Shi Single-seat Fighter (later A5M Claude) and the 8-Shi Special Reconnaissance Aircraft (which evolved into the G3M Nell), bringing Japanese aeronautical engineering capabilities to par with Western standards.
As this success became evident, the new technology spread to other Japanese aircraft manufacturers for both Army and Navy use. From 1935 onwards, the Navy expanded its aircraft repair and supply facilities. At Hirosho, additional land was developed through mountain cutting and coastal land reclamation, eventually leading to the establishment of branch arsenals at Ohita and Maizuru. On October 1, 1941, all aircraft departments of Naval arsenals were reclassified as Naval Air Arsenals, distinct from the previously renamed Naval Air Technical Arsenals. With this reorganization, Hirosho became the 11th Naval Air Arsenal.
Hirosho then shifted its focus to augmenting production of aircraft types developed by other manufacturers to support the war effort. Among these were the Nakajima Navy Type 97 Carrier Attack Aircraft (Kate) and Aichi Navy Type 0 Three-seat Reconnaissance Seaplane (Jake), followed by the Aichi Navy Carrier Bomber Suisei (Judy) and various Navy engines from commercial manufacturers. No new aircraft designs were attributed to Hirosho after the Type 95 Attack Aircraft (G2H) of the mid-1930s, as the development function was transferred to Kugisho.
The last aircraft designated with a Hiro code was the H10H1 14-Shi Medium Flying-boat, though it was never completed due to higher wartime priorities.
More pictures including drawing:
Statistics:
Twin-engined land-based mid-wing monoplane bomber.
All-metal stressed skin construction.
Crew of seven.
Two 900-1, 180hp Hiro Type 94-1 eighteen-cylinder W-type water-cooled engines, driving four-bladed wooden propellers.
One nose-mounted flexible 7. 7mm machine-gun, twin dorsal 7. 7mm machine-guns retractable turretmounted, one retractable turret-mounted ventral 7.7mm machine-gun.
Bomb load:
six 250kg (551Ib) bombs or four 400kg (881Ib) bombs.
Span: 31.68m (103ft 11 1/4in);
length: 20.15m (66ft 1/4in);
height: 6.28m (20ft 7~in);
wing area: 140sq m (1,506.996sq ft).
Empty weight: 7,567kg (16,682Ib);
loaded weight: 11,000kg (24,250Ib);
wing loading: 78.5kg/sq m (16Ib/sq fr);
powerloading: 6.11 kg/hp (13.4lb/ hp).
Maximum speed: 132kt (152mph) at 1,000m (3,280ft); cruising speed 90kt (104mph);
climb to 3,000m (9,843ft) in 9min 30sec;
service ceiling 5, 130m (16,830ft);
range 1,080 to 1,557nm (1,245 to 1,800sm).
Hirosho built six from 1933 and
Mitsubishi built two from 1936.
Statistics pictures:
Spoiler
- Yes
- No
- Other
Source:
- Mitsubishi Aircraft Co Ltd:
Navy Type 95 Land-based Attack Aircraft (G2H1) - Japanese Aircraft, 1910-1941 (Putnam Aeronautical Books)
Japanese Aircraft, 1910-1941 (Putnam Aeronautical Books): Mikesh, Robert, Abe, Shorzoe: 9781557505637: Amazon.com: Books - Trans-Oceanic Bombing of China, 1937 - Pacific Eagles
- https://weaponsandwarfare.com/2016/06/22/hiro-g2h/