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. The Chinese Air Force needed a long-range bomber to enhance its ability to deter powerful enemies due to changes in China's potential combat targets. Because the bomber-6 bomber is difficult to perform long-range strategic bomber missions, after the bomber-6 bomber entered service, the Chinese Air Force put forward the idea of ??developing a long-range strategic bomber.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.
In order to meet the requirements of the Chinese Air Force to increase the range of the bomber -6 bomber and increase the service life of the aircraft, in the case that it is difficult to provide a turbofan engine in a short period of time in China, Xifei in order to further meet the air force to increase the range of the bomber -6 and increase the use of the engine The requirement of life was proposed in June 1970 to retrofit the H-6 with four British "Spey" Mk.512-5W turbofan engines in order to increase the range of the aircraft by improving the economy of the engine. Called Boom-6I. After approval by relevant departments, the design of the H-6I began in February 1971, the final assembly was completed in 1977, and the first flight of the H-6I was carried out in January 1978.
The H- 6I maintains the basic shape of the H-6 prototype, and adds a "Spey" engine in the middle of the wing , which effectively improves the power performance of the H-6 . After half a year of test flight, it was proved that after the turbofan engine was replaced, the take-off / landing, climb performance and range have improved significantly. It met the requirements of the original design and entered the ranks of long-range bombers in one fell swoop. But in the end, China began to reduce its military spending on a large scale in 1980. Therefore, after modifying one aircraft, obtaining experimental data and modification experience, the development of the H-6I was abandoned. It can be considered that the H-6I is the basis for the development of the H-8.
The designer also designed the H-8 by enlarging the H- 6, with a length of 48.50 meters, a height of 13.85 meters, and a wingspan of 46.47 meters . The maximum take-off weight is 163 tons; the normal load is 7 tons, the maximum load is 18 tons, and the attack weapon can carry 13 AS-5 air-to-ground missiles or 9,000 kg of domestic aviation bombs. It can also drop nuclear bombs. With a load of 7 tons, the range is 11,000 kilometers. The aircraft has a maximum level flight speed of 1000 km / h, a cruise speed of 800 to 850 km / h, and a ceiling of 13,000-14,000 meters.
Although the bomber -8 bomber has a smaller range and load capacity than the US B-52 strategic bomber, taking off from a Chinese base is enough to carry out a strategic nuclear counterattack against the important political, economic and military bases of the two superpowers, the US and the Soviet Union. Enlarging the H- 6 into a long-range strategic bomber has little technical difficulty and risk, and the cost is not high. With the strength of the Chinese aviation industry at that time, it could solve the problems of engines, airborne electronic equipment, technology, and airborne weapons. The bomber -8 bomber should be successfully developed. However, in order to centralize the development of large domestic aircraft, it was decided to suspend the development of the Bomber 8 bomber and concentrate its efforts on the research and development of the large passenger transport -10 aircraft at the time.
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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