DF-4 - Flight Testing
The first launch test of the Dongfeng No. 4 missile was determined as the "short-range overall scheme verification" test, and a tower launch was conducted at the Jiuquan test base to investigate the feasibility of the overall design scheme, focusing on evaluating the two-stage separation and second-stage engine high-altitude ignition performance. In October 1969, during the final preparation of the No. 01 missile at the launching position, a major accident in which the primary engine had to be replaced due to the accidental explosion of the primary engine shut-off valve occurred. After inspection, the accident was caused by a poorly designed test route. The missile was re-tested at the technical position after replacing the engine, so it did not participate in the first flight test.
On November 16, the 02 missile conducted a flight test. After the rocket fired into the air, the first stage was not shut down during flight, the second stage was not ignited, the two stages were not separated, the missile self-destructed and the test failed due to a failure of the command system. After inspection, the reason for the failure of the test is that the program distributor in flight stopped halfway, mainly due to the quality of the equipment. Missiles have both technical and technological quality problems, and when they are tested at the test base, they also have operational errors and improper handling. To this end, all test participants summed up their experience in depth, carefully implemented the "serious, thoughtful and meticulous, safe and reliable, foolproof" test policy, conducted a large number of stand-alone tests and multiple system inspection tests to eliminate mutual interference between systems Wait for failures and hidden dangers. Take measures to improve the reliability of the program distributor and increase the backup signal of the first level shutdown time to ensure that the two levels can be separated normally according to plan.
On January 30, 1970, the No. 01 missile after the engine replacement was successfully tested at the Jiuquan test base, and the two-stage separation was normal. The second stage rocket engine successfully ignited at high altitude, the control instrument was working normally, the warhead landed near the intended impact point, the deviation of the impact point was small, and the test was successful. The results of this test prove that the overall technical solution for medium and long-range missiles is feasible and the work of each system is coordinated. This successful launch is of great significance. On the one hand, it marks that China has mastered the two-stage rocket technology, and at the same time, it also laid a solid foundation for the successful launch of the Long March 1 carrier rocket. Three months later, on April 24, 1970, the Long March 1 rocket equipped with a third-stage solid engine based on the Dongfeng 4 missile successfully launched China ís first artificial earth satellite, Dongfanghong-1, to the perigee 439 Kilometers, apogee is 2384 kilometers, and the inclination angle is 68.5 degrees in low-Earth orbit. China has become the fifth country in the world to independently develop and launch artificial earth satellites.
In order to further test the tactical and technical performance of the Dongfeng No. 4 missile, a long-range test was subsequently started, and the performance of underground refueling, wellhead launching schemes and weapon systems was evaluated. Compared with the previous Dongfeng series missiles, the underground refueling and wellhead launching scheme greatly reduces the exposure time of the missile on the ground and improves the survival performance. Long-range tests are mainly conducted at the Northeast Missile Proving Ground. The Northeast Proving Ground began construction in the deep mountain and dense forest in April 1967, and completed the proving ground area in August 1970. In September 1975, the Central Military Commission decided to convert the Northeast Proving Ground into a Northeast Missile Test Base. Xia Bing served as commander, and Yang Tongshan served as political commissar. After the base was established, according to the needs of the test mission, a part of the test facility was expanded.
Since May 31, 1966, the National Defense Science and Technology Commission, the Chinese Academy of Sciences, and the Ministry of Seven Machines have jointly agreed to launch China ís first artificial satellite launch vehicle, the Long March 1, based on a medium- and long-range missile and a third-stage solid rocket. The man-made satellite program is closely linked to medium- and long-range missiles, and is therefore highly valued by the central government. On November 23-24, 1967, the National Defense Science and Technology Commission and the National Defense Industry Office jointly decided to require the First Institute of the Seventh Ministry of Aircraft to conduct full- and long-range missile full-bomb test runs in April 1968, and conduct joint training from May to June. Experiment, and strive to launch satellites before the National Day in 1968. On January 4, 1968, the Office of the Central Committee of the Central Committee notified: The nineteenth meeting of the Central Committee of the Central Committee confirmed that Dongfeng No. 4 is an important model and cannot be abandoned or shaken. We must actively adjust our strength, make arrangements, and demand to launch the first artificial satellite in 1968.
During the critical period of Dongfeng No. 4 carrying out large-scale experiments, the scientific research work of the Seventh Machinery Department was greatly disturbed and destroyed by the "Cultural Revolution". In order to overcome the impact of the "Cultural Revolution", Zhou Enlai summoned the relevant personnel of the First Institute of the Seventh Machinery Department and the Dongfeng No. 4 full-bomb test drive on April 9, 1969, May 10, and May 10, 1969 to persevere with meticulous attention jobs. He clearly pointed out that the test drive is a matter of national honor and no one should interfere. In order to clarify responsibilities, ensure product quality, and develop according to plan, he asked the personnel who undertake the development tasks to obey the command and stick to their posts. After direct enquiries by Zhou Enlai, the first and second stage tests of Dongfeng 4 on May 19 and June 4 were successful.
On July 17, 18, 19, and 25, 1969, Zhou Enlai held consecutive meetings to resolve the ground test problems of the Long March 1 Rocket Level 2 and Level 3, and assigned Qian Xuesen to handle the test drive matters. And asked the 29 units participating in the Dongfanghong-1 satellite launch project a total of 3456 people must hold their posts and obey the command.
On July 30, 1969, the First Academy of the Seventh Ministry of the Ministry of Aeronautics proposed a group of flight test outlines for the 01 batch of Dongfeng IV. On August 22, the National Defense Science and Technology Commission approved the agreement. On August 27 of the same year, the first Dongfeng No. 4 test ejection plant was transported to Jiuquan base to prepare for flight test. The technical command responsible for the first test was Ren Xinmin. The test of Dongfeng-4 is not only related to the successful development of China's first medium and long-range missile, but also directly affects whether Changzheng-1 can successfully launch China's first artificial earth satellite. In addition, due to the increased range of Dongfeng-4, whether the missile will fly out of the country due to control system failure during the test is also a major issue to be considered. To this end, Zhou Enlai specifically listened to the report before launching, and inquired in detail about the quality of the missile and the flight safety measures taken.
On November 23, 1970, the first long-range flight test of Dongfeng IV (01 batch of No. 6 bombs) was conducted at the Northeast Proving Ground. However, due to the failure of the digital computing device, the shutdown signal of the first-stage rocket failed to be sent, and the second-stage rocket failed to ignite. After flying until the first-stage propellant was exhausted and shut down, it self-destructed in the air due to unstable attitude. Premier Zhou Enlai immediately instructed: "We must sum up our experience, make persistent efforts, and strive to fight next time." The local government and the masses found and submitted the missile wreckage, which provided an important basis for analyzing the fault. The launching force and the development unit organized technical personnel to carefully analyze the test data and wreckage, find out the cause of the failure, and take corresponding improvement measures in the design.
On November 15, 1971, the second long-range test of Dongfeng No. 4 was successful, with a range of 3772 kilometers. This was also the first time that Dongfeng 4 was launched using underground injection and wellhead firing. But the warhead re-enters the ablation and damages, and the tip burns through. Tests have shown that under the long-range state of the missile, the various systems work in a coordinated and reliable manner. The test also tested the launching method and obtained data on the warhead reentry test environment and warhead ablation. The success of this test showed that Dongfeng 4 possessed medium and long-range range capabilities, marking China ís complete solution to the difficulties of inter-stage connection and separation of two-stage missiles, high-altitude engine ignition technology, missile attitude control and guidance technology. The missile technology has advanced to a new stage.
After the Sino-Soviet Treasure Island incident in March 1969, the danger of the Soviet Union ís nuclear strike against China rose sharply, and the troops urgently needed missiles capable of effectively countering the Soviet Union. At that time, the East Five missile had not yet flew for the first time, and the medium- and long-range missile range (4000km) set in the "Eight Years Four Bombs" was not enough to strike Moscow from western China (such as Qinghai). In June 1970, Qian Xuesen and Yang Guoyu, heads of the Seventh Machinery Department, went to the First Academy to listen to their opinions and expressed their agreement with the proposal to increase the range of medium- and long-range missiles. In July, the thrust-increasing engine passed a 280-second long test run. Subsequently, the National Defense Science and Technology Commission formally reported to the Central Special Committee on medium-range and long-range missile range proposals. In August, Zhou Enlai officially approved the extension plan at the Central Special Committee and instructed: Do nít change too much, and get it out quickly. Due to the influence of the "Cultural Revolution", this development work was almost at a standstill. It was not until 1975 that it was adjusted and rectified that a turnaround occurred. After improving the design and adopting the technical measures to increase the range of the missile, since May 1976, several evaluation flight tests have been conducted.
On May 15, 1976 and August 25, 1976, the improved Dongfeng IV 02 batch 1 group two flight tests succeeded successively, proving that the extended range design was correct, and the warhead thermal barrier was tested to meet the need to increase the thermal protection after the range Ability requirements. Subsequently, a full flight test of Dongfeng No. 4 was conducted. On September 30, 1977, for the first full-scale test, the missile self-destructed due to the failure of the safety contact circuit during the first flight of 84 seconds. On November 22, the second full flight test was a complete success, with a range of 4,167 kilometers, and the matching performance of the two bombs was evaluated. This is also the first time that the Second Artillery Force has launched this type of missile. In order to strengthen the leadership of the improvement work, in January 1978, Li Yiming was formally appointed as the chief designer of medium and long-range missiles. In April 1979, Dong Chun was appointed chief commander. On July 31, 1978, September 16, and December 23, 1978, three full-range flight tests were conducted. The first two were successful, and the third failed. These tests have initially verified the combat performance of the Dongfeng 4 missile and evaluated the nuclear warhead's control system. In order to improve the accuracy, Dongfeng No. 4 also carried out lateral correction from the 8th round of the 02 batch, and achieved good results.
The Dongfeng No. 4 development mission statement requires that the missile should have the ability to be parked in the well for 15 days after being filled with propellant, and then upgraded to the wellhead to launch. On February 9, 1980, a flight test to verify this function was successfully conducted.
In the second batch of improvements to the Dongfeng No. 4 missile (02 batches and 3 groups), a large number of improvements were also made to the launch mode, storage performance, and safety performance to enhance the missile's survivability and performance. In May 1975, the central government approved the Dongsi to increase the storage of flat holes and the launching method of the trailer ground. On August 2, 1980, it was successfully launched for the first time by using the towed field launch method. The missile was flying normally and the warhead hit accuracy was very high (the deviation of the landing point was 0.079km in the longitudinal direction and 1.177km in the lateral direction). The "cold" test of the nuclear warhead was also conducted during the flight test. The success of this test is of great significance. The CPC Central Committee, the State Council, and the Central Military Commission sent a congratulatory message to the Northeast Base on August 5. On October 31 of the same year, the second towed yard level test was also successful.
By the end of October 1980, a total of 11 launch tests of 02 batches of Dongfeng IV proved that the two missile improvement schemes were correct and feasible, the performance of the entire system of the missile met the requirements of tactical technical indicators, the new launch method was feasible, and the launch equipment and launch procedures were in compliance with combat. Basic requirements in the state. Through these tests, the reentry strength and heat resistance of the warhead were also tested, and the technical performance of the whole system under high temperature, low temperature, filling and parking, storage, rain and wind load conditions was tested. During this period, a simulation test of the combination of the two bombs, a magnetic recording device ejection recovery test, and a working life test of the onboard instrument were also carried out, and the combat performance such as night operation and reaction time of the system was tested.
From 1980 to 1983, Dongfeng No. 4 completed the design and process setting. On June 29, 1983, the State Council and the Central Military Commission approved the finalization of the Dongfeng No. 4 missile nuclear weapon. On August 6, 1988, the improved Dongfeng No. 4 nuclear warhead was finalized.
It took 18 years from the development to the finalization of the Dongfeng 4 missile, which was significantly delayed than the original development plan, which affected the equipment time of the troops. In addition to being dismounted in the middle and delaying the development progress, during the entire development process, due to the increase of range and the change of launch mode, the technical state of the missile has been significantly revised many times, and each time it is changed, a batch of flight tests will be added. This makes the entire development cycle longer. For a missile weapon system, the tactical and technical indicators must be fully demonstrated. Try not to modify the indicators during the development process, so as to avoid modifying the overall plan, changing the technical status, and delaying the development cycle.
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