H-8 - First Instance
There is very little open information on efforts to develop a successor to the H-6. The design requirements of the Chinese Air Force for the H-8 are mainly for strategic use and can also be used for campaign or tactical purposes. It can carry conventional weapons, air-to-ground missiles, nuclear bombs and other weapons. It can be used at night under complex climate conditions. It can attack enemy political, economic, and military sites, or bomb enemy tanks, artillery groups, maritime fleets, and large ships.
China began work on a new generation long-range bomber in the early 1970s. In the 1970s, after solving the problem of self-produced H-6, the development of a "long-range strategic bomber" based on H-6 was put on the agenda. Since the H-6 uses a turbojet 8 based on the Soviet RD-3M engine, the thrust is insufficient and the fuel consumption is high, so we must first work on the engine.
In the search for a faster bomber that could carry a heavier load, Xian tested an H-6 re-engined with four Rolls-Royce Spey Mk512-5W turbofan engines - two in the wing roots, which necessitated smaller intakes than the stock H-6 engines used, as well as two more engines on pylons on the wings.
The fuel-efficient Rolls-Royce Spey Mk-512 turbofans were originally used on the Trident 2E civil aircraft. The Trident was one of the first jet-powered civilian transports acquired by the PLAAF. The order included an agreement to produce the Spey engines under license, and these license-produced engines were subsequently used on the JH-7 military aircraft.
Xifei proposed the H-6I (English letter I, not number 61) in 1970, which adopted the best and most advanced aviation equipment that China had at the time—introduced when purchasing the British Trident 2E civil airliner "Spey" 512-5W turbofan engine. The other performance of this engine is good, but the thrust is small, so the H-6I uses a four-engine scheme, two of which are arranged in place, and the other two are hung under the wing. This plan started in February 1971 and completed the assembly in 1977. This seemingly peculiar test aircraft made its first flight in 1978, and its actual performance can basically reach the United States B-47, close to the B-52.
The resulting H-6I made its first flight in 1978, though no photographs of this aircraft in flight have emerged. The H-6I flight testing demonstrated an approximately 50% increase in range over the standard H-6 with significant improvements in speed and climb rate. However, the project was canceled with only a single example built as the costs of maintaining and operating the Spey engines proved uneconomical. Plans to modify the entire H-6 fleet were not implemented.
Due to the replacement of the Spey Mk. 512-5W turbofan engine, the fuel consumption and thrust-to-weight ratio have been greatly improved. The maximum sea level climb rate of the H-6I increased from the original 18.6m / s of the H-6. 29.7 m / s, an increase of 60%. The maximum range has also increased from 5760 km to 8060 km, and the combat radius has increased from 3600 km to 5000 km. Therefore, the improved H-6I can basically meet the operational requirements of the Chinese Air Force for long-range targets.
However, because the source of the Spey Mk. 512-5W engine was difficult to guarantee, coupled with maintenance costs and logistical guarantees, it was difficult to achieve the end. After the H-6I modified one, it stopped the subsequent development. However, the relevant data accumulated by the H-6I laid a solid foundation for the subsequent development of the H-8 bomber.
In early 1972, China began a technical mapping of the wreckage of a Pakistani Boeing 707 that was damaged when it landed in China, which also enabled China Airlines to understand the relevant technology of the US turbofan engine. Since there are many technical problems in the development of the Chinese turbofan 6 engine, relevant Chinese authorities have proposed that the JT-3D turbofan engine equipped with the American Boeing 707 passenger aircraft can be equipped with a new type of strategic bomber being developed. In the end, the new Chinese bomber was named the H-8, which can be regarded as an enlarged and improved version of the H-6.
In the early 1980s the Xian H-6M (first use of the designation- the current H-6M is less radical maritime attack version of the H-6) re-did the wings of the bomber to accommodate four high-bypass ratio turbofan engines roughly in the low end of the CFM56 class. After the turbofan engine was replaced, the performance of the H-6I in takeoff, landing, climb, and range was greatly improved. The maximum range was increased from 5760 km to 8060 km, the combat radius increased by 40%-from 3600 km to 5000 km, and the maximum climb rate at sea level increased by 60%-from 18.6 m / s to 29.7 m / s. In terms of combat radius alone, if it takes off from Urumqi, Moscow will be within the scope of the bombing, and it is really a long-range bomber.
From the published information, it can be known that the H-8 bomber is equipped with 4 wing-suspended 910A turbofan engines, or 6 JT-3D turbofan engine tunnels, with a length of 48.5 meters, a height of 13.85 meters, and a wingspan of 46.47 meters. It has an empty weight of 65 tons, a normal take-off weight of 155 tons, a maximum take-off weight of 163 tons, a maximum payload of 18 tons, a maximum range of 11,000 kilometers, a cruise speed of 850 kilometers per hour, and a maximum ceiling of 14,000 meters. The configuration of its crew is basically the same as that of H-6, with a total of 6 people, including forward pilot, co-pilot, pilot, radar pilot, rear gun shooter and correspondent. The fuselage was slightly stretched and the aft fuselage sighting stations were deleted. This initial effort reportedly featured four Rolls-Royce Spey turbofans under the wings, and a fuselage generally resembling an enlarged H-6/Tu-16 Badger. The resulting bomber was said to be comparable in general performance to the American B-47. This performance was evidently unattractive, and the Chinese government cancelled the program before it moved out of the concept stage. It never made it off the drawing board.
In the 1980s the Xian H-8II design took the H-6M, stretched it, enlarged the fin, added a new attack radar in the nose and stretched the wings to accommodate six turbofan engines. The performance of the new bomber would be further improved-the six-engine solution is simply the Chinese version of the B-52. Unlike the previous projects, this was the level that China's technical forces could achieve at that time, and it was not whimsical. The military originally planned to shape the H-6I into "H-8" and put it into mass production in 1979. However, at that time, the state paid more attention to another project, "Yun10", and various resources must be superiorly guaranteed; the second was from 1980 At the beginning, because economic construction became the central task of the country, military expenditures were greatly reduced, and the cost of a large number of improvements to the H-6 was insufficient. Third, at that time, the "Spey" engine had not yet been domestically produced, and there were some problems with the quantity and maintenance. Under the combined effect of various factors, Hong-8 ended without issue. It never made it off the drawing board. Internet sources have offered pictures of what is referred to as the H-8.
After the 1980s, China's international environment generally slowed down. Long-range strategic bombers are not urgently needed, and it is right to slow down a bit. In fact, the Chinese Air Force took another, lower-cost approach—a small improvement to the H-6, and the ability to carry cruise missiles to maintain strategic strike capabilities. At the same time, the H-8 project also accumulated sufficient turbofan modification experience, and used the H-6 improved version. The active H-6K was equipped with a copy of the Russian-made D30-KP-2 turbofan engine. The turbofan 18 has a range of 9,000 kilometers, which exceeds the target of the four-round H-8 program. It can be seen that the H-8 project still has considerable credit.
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