H-6K - Powerplant
The biggest difference between the improvement of the H-6K and other H-6 modifications is the replacement of the Russian-made D-30KP-2 turbofan engine, which is the power unit of the Il-76MD transport aircraft. Fitted with D-30-P2 turbofan engines of greater thrust and lower fuel consumption than the original WP-8 turbojet engine, the new H-6K has a greatly increased range and combat payload. The two engines, each with a thrust power of 12,000 kilograms, may enhance the H-6K's payload capacity to around 12 tons, enabling it to carry six large long-range cruise missiles. This latest model of H-6 family switched to the more powerful of Russian-made D-30KP2 Aero Engine. According to sources, XAC produced 2 H-6K for PLA's evaluation and testing. Since the design modification is dependent on an imported power plant, the production was initially at a very low rate of 2-3 H-6K in one year.
The D-30KP-2 is a turbofan engine developed by Russia’s Soloviev Design Bureau (now known as Perm Aero Engine Research and Production Consortium). Its maximum thrust is 12.5 tons, bypass ratio 2.42:1, and overhaul life 3000 hour. D-30KP is the first high-performance turbofan engine with large bypass ratio developed in the former Soviet Union. It is characterized by large thrust, low fuel consumption and reliable performance. The author only has the performance data of D-30KP. Fortunately, D-30KP-2 is improved on its basis, and the performance data may not be much different. Since D-30KP has a reverse thrust device, and the H6K does not need to install this device, the following performance analysis is all models without reverse thrust device. The maximum thrust of the D-30KP engine is 12000 kg, the takeoff fuel consumption rate is 0.49 kg/kg·h, the cruise fuel consumption rate is 0.70 kg/kg·h, and the thrust-to-weight ratio is 4.79; the engine diameter is 1464 mm, the maximum diameter of the casing is 1560 mm, and the length is 5700 mm. (With reverse thrust device), the weight is 2300 kg (the weight of D-30KP-2 is 2318 kg). The corresponding data of the turbojet-8 engine used on the original H6 is: engine rated thrust 7650 kg, maximum thrust 9500 kg, maximum fuel consumption rate 0.97 kg/kg-hour, rated fuel consumption rate 0.91 kg/kg·hour, cruise consumption When the oil rate is 0.89 kg/kg·, the thrust-to-weight ratio is close to 3. The engine has a diameter of 1,400 mm, a length of 5315 mm, and a weight of 3,230 kg. It can be seen from the above comparison data that, compared with D-30KP turbojet-8, it has higher thrust, lower fuel consumption, lower weight and higher thrust-to-weight ratio. The D-30KP-2 used on the H-6K has better performance than the D-30KP, with a maximum thrust of 12.5 tons. Due to the replacement of the new engine, the supporting body needs to be modified accordingly. In order to speed up the development progress and reduce the difficulty of work, no major changes were made to the main bearing structure of the H-6, and only targeted redesign and modification of the intake duct and tail nozzle for the replacement, and the aerodynamic matching of the main wing and tail Make appropriate adjustments to meet the impact of increased engine air intake and thrust on the aircraft. For the D-30KP turbofan engine with a large bypass ratio, its cruise thrust is generally 1/4 to 1/3 of the maximum thrust; that is to say, during most of the flight of the aircraft, each engine provides thrust for the aircraft About 2 to 5 tons (1 kN equals 101.968 kg of thrust), and the cruising fuel consumption rate really determines the range. According to the official nominal data comparison, in terms of cruise fuel consumption, the D-30KP-2 is about 20% lower than the turbojet-8, which means a significant increase in range and combat radius. The general media said that the H-6 push-to-weight ratio reached 0.33 and so on, but in fact it has limited meaning. The actual significance of this aircraft's maximum thrust-to-weight ratio is different from that of jet fighters. Its maximum thrust state occupies a very small proportion in the entire flight, and it is basically only seen in the take-off phase and large maneuvers in very special circumstances. The new engine can of course also provide more thrust for the aircraft, but it should be noted here that the increase in bomb load caused by the increase in engine thrust is very limited. For the H-6, the cruise flight state has been determined at the beginning of the design. That is to say, under the premise of the same aerodynamic shape (meaning that the cruise lift-to-drag ratio remains unchanged), the aircraft The increase in weight may cause the cruise speed to deviate from the optimal design cruise speed by a small amount (although the offset may be minimal). Generally speaking, the increase in ammunition capacity of the new H-6 is more attributable to the reduction in the empty weight of the fuselage, which in turn is derived from the use of composite materials, the updating of airborne equipment, and the abandonment of some old technical equipment. In short, the direct benefit of replacing the turbofan engine is that the range of the 6K has been greatly increased, and the bomb load has also been greatly improved. On 23 July 2010 Russian media reported that China would be provided with 32 D30-KP-2 aero-engines for the H-6K bombers. Because the D30-KP-2 engine delivery had been delayed, the full production of the H-6K had been delayed from 2007. The delivery of the 32 new engines would allow the H6K production line in China to restart. According to these reports, at least 16 D30-KP-2 engines would be used to assemble 8 H-6K bombers, and the rest will act as a store of spare parts. Although the supply contract between China and Russia for the Il-76 transport aircraft did not become effective, Russia intended to fulfill within the main framework agreement the supplement contract of supply of the D30-KP2 engine to China. According to the related agreement, these engines were originally to be used in the Chinese Il-76 transport aircraft's backups. But the Chinese side actually prepared it to change them for the domestically produced new bomber aircraft production.
The final fifth batch of the D-30KP-2 engines manufactured by Research and Production Association Saturn was delivered to the Chinese customer on 23 March 2011. The batch is comprised of 11 engines manufactured under an agreement between Russian State Intermediary Agency for Export and Import of Military and Dual-Purpose Products, Technologies and Services (Rosoboronexport) and People's Republic of China becoming effective in April 2009. The agreement provided for supply of 55 engines until 2012. The final batch of D-30KP-2 engines was scheduled for delivery before the end of March 2011. The agreement also provided for technical support by the manufacturer during the warranty period.
The previous four batches of D-30KP-2 were delivered by the Russian side in November 2009, March, May and October 2010, respectively. The Chinese delegation and the representative of the Chinese Embassy in Moscow Zheng Kai were satisfied with early and high-quality performance by Saturn of its obligations under the agreement. According to Sergei Popov, commercial director at OAO NPO (Research and Production Association) Saturn, "NPO Saturn, which has longstanding friendly relations with the Chinese customer, takes pride in effective completion of this agreement. We look forward to continuing Russian-Chinese cooperation, in particular, supplying D-30KP-2 engines to China."
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