Recently, the reporter learned from interviews on the hot-selling sites of several real estates that many rich consumers are worried about not being able to buy a "heart water" apartment, and this hot-selling sign has aroused great concern and comments in the industry: Guangzhou property market has returned to the seller's market? However, many facts show that the confidence of buyers and sellers to enter the market has greatly increased after the hot sale of the Eleventh Golden Week. At present, Guangzhou property market can be said to be a "transitional period" (from the end of 10 to the end of10), which is in the middle of the Eleventh Golden Week and the peak season of the property market around the end of the year. However, under this special condition, there were three "strange phenomena" in Guangzhou 165438+ 10.
Strange one: the market is in short supply, and the products are in short supply?
It can be seen from the official public sale of buildings such as Xinghui Qingxuan and Yuan Juan last Saturday that the consumer demand is obviously greater than the market supply, and many consumers can't buy "Heart Water" units. In this regard, Jingwei real estate analysis pointed out that from the development curve of consumer demand, the current consumer demand is still on the rise, and good houses and high-quality communities are really not worried about selling. The reason is that the push of goods by developers is obviously reduced, and most developers have entered the final stage to prepare for the sales at the end of the year and next year. It is precisely because the demand curve of consumers is different from that of developers, so the current property market is slightly in short supply.
However, Han Shitong, a real estate expert, believes that the current shortage of the property market in Guangzhou is only temporary and superficial, and it can even be said to be false and artificial. The argument that the supply is in short supply is not established. There are many reasons for this so-called shortage. Objectively, it may be due to the strengthening of project management and supervision, which has affected the progress of developers in rushing to work; Moreover, the implementation of online trading, unskilled operation will also lead to a certain transaction lag. However, the main reason is that the developer is property hoarding, slowing down the sales progress to achieve the purpose of hoarding.
Monster 2: Will the shortage of supply drive up the house price?
According to the data of "Sunshine Home", as of1the morning of October 9th 1 12: 00, the saleable buildings in the whole city (excluding Panyu and Huadu) 14 1, and saleable commercial houses 16466. However, the latest hot-selling new products include Xinghui Qingxuan, Qiyuan Garden, Hong Guang Dieshui Rainforest, Vanke City Garden Phase II, and Tuscany, Jiangnan Garden Phase II, Ximenkou Plaza Phase II, Fuji Plaza, Evian Town, Guangzhou R&F, Yuanbang Yue Ming Garden, Dongfeng Plaza Phase I, Dadongmen Hua Ting, etc., which are being registered. So many new dishes and goods are pouring into the market one after another. In addition to the large supply, will it drive up the property prices in Guangzhou?
Han Shitong pointed out that under the current economic situation, it really remains to be seen whether there will be a situation in Guangzhou where property prices are only rising but not falling and the market is in short supply. But there is no doubt that the so-called oversupply in the market is actually caused by property hoarding, the developer, slowing down the sales pace.
So, what is the price trend of the property market at the end of the year? No one has a bottom at present. Because, if the National Day property market sales are not ideal, it is estimated that the sales pressure will be even greater at the end of the year, and there will even be competition for price reduction; If the sales are ideal, it may further drive and raise the property price, but the transaction may shrink. At present, market voices are trying to create an atmosphere in which property prices only go up but not down, and the market is in short supply, and they are convinced of this. The development and change of Shang Ruo real estate market is not the case. Obviously, the ability of developers to deal with emergencies will be affected by inadequate preparation.
Strange image 3: is it fashionable to send a lottery ticket to sell a house in the property market?
From 10 to now, some people sell houses in lots and some people sell shops in lots ... This series of marketing techniques has to attract the attention of the media. According to Jingwei Real Estate, the difference between sending chips and selling them naturally is that sending chips can gather popularity, enliven the atmosphere at the scene and realize centralized selling; At the same time, developers can know the needs of consumers in advance, which is convenient for timely adjustment of products and sales strategies.
Developers redistribute preparation and sales to natural sales, indicating that developers are more confident in product sales. However, according to the reporter's observation, sending chips is still the main sales method of developers at present, but the specific operation mode of queuing lottery has changed: from the previous queuing sales to lottery sales, which at least shows two points: First, the operation is fairer, avoiding many human interference factors; Second, the operation is more humanized, eliminating the hard work of prospective buyers queuing.
However, an expert who did not want to be named revealed that at present, the more popular marketing method in the market is to send or recognize funds. Some real estate customers last for half a year or as little as a few months. During this period, they are still in the internal subscription stage, and the detailed sales price is not announced, and the house selection is not made public. After observing the market dynamics for a period of time, we began to create a lively scene of "queuing" to enter the market and increase the sales of real estate in a popular way.
The need of actual combat 9
From the end of 1960 to 196 1 spring, Khrushchev expressed his willingness to ease the relations between the two countries to China. Since 1959, the once tense Sino-Soviet relations have improved slightly. Although the two countries were in the autumn of 196 1, this "second honeymoon", which lasted less than one year, brought them an extremely precious gift-MIG 2 1 fighter. [P6
1962, the fighter plane 12 MIG -2 1 directly imported from the Soviet Union began to join the China Air Force, numbered "Destroyer 7". At that time, its main operational target was the U-2 high-altitude reconnaissance plane of the United States, which often cruised over China with its extraordinary high-altitude performance. MB)a
It should be said that in the early 1960s, the J-7 was a fighter with excellent performance, not to mention in the China Air Force, even by the international standards at that time. However, from the winter of 1963 to the beginning of 1964, the J-7 aircraft has been exposed to a series of high-altitude operations, such as short ceiling time, poor high-speed performance at high altitude, no radar and poor high-altitude maneuverability. In addition, combat firepower and take-off and landing performance also need to be strengthened and improved. nltb(%
Actual combat needs are overwhelming! China's aviation industry has just begun to try to be completely independent, and immediately began to develop a new generation of fighters based on MIG 2 1. ^8.
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Second, the twists and turns of the selection process \$A
Starting from 1964, the No.3 Engine Department 60 1 Institute began to consider improving the J-7 to meet the requirements of high-altitude operations. 1964101On October 25th, the Sixth Hospital held the "MIG-1 2 1 and Il -28 Improvement Preparatory Meeting" in Shenyang. At the meeting, 60 1 proposed two modification schemes of MIG -2 1: S.*aP,
The first scheme is the gradual modification of MIG -2 1: the aerodynamic shape of the aircraft is the same as that of MIG -2 1, and the nose intake mode is also adopted. The engines are changed from single to double, and two turbojet 7 engines are installed. Simply put, this machine is an enlarged version of MIG 2 1 5q
The first scheme is a major modification of MIG -2 1: the aerodynamic layout of the aircraft has been greatly modified ―― the air intake mode of MIG -2 1 is replaced by the air intake mode on both sides of the fuselage, leaving room for the layout of new airborne radar on the nose. The engine will continue to adopt a single engine layout, but 606 newly designed afterburner turbofans with a thrust of 8,500kg are selected. P
From the initial design index, the flight performance of the two schemes is equivalent to that of the American F-4B, that is, the ceiling is 20,000m, the maximum Mach number is 2.2, the basic range is1600 km, and the weight is about 10t. Pl
On June196565438+1October 12- 17, the Third Machinery Division held a meeting of leading cadres of aviation enterprises and institutions in Beijing. During the meeting, Vice Minister Duan Zijun presided over a symposium on the development of new aircraft. Considering that the research on turbofan engine in the international aviation industry was just in its infancy at that time, China's aviation industry only had the experience of imitating and improving the Soviet turbojet engine, the meeting unanimously agreed to take MIG -2 1 as the prototype to make a double-engine design scheme, thus determining the development direction of J-8. kR[； ordinary
Although purely from the technical indicators, the second scheme is undoubtedly more attractive. However, considering that China's aviation industry did not basically master the production technology of MIG 2 1 until 1967, it is undoubtedly more pragmatic and reliable to choose the first scheme. rw\rQY
60 1 Institute investigated the relevant technical situation at home and abroad while learning about MIG -2 1 according to the first scheme originally put forward, and put forward the preliminary tactical and technical requirements of the J-8 aircraft, which was reported to the Sixth Hospital on March 1965. /IJ
As a direct improvement of MIG -2 1, the guiding ideology of this scheme is mainly based on the shortcomings exposed by MIG -2 1 in actual combat, making various targeted improvements ―― highlighting high-altitude and high-speed performance, increasing range, increasing climb rate and strengthening firepower. y
The specific performance requirements are: 6 [q >; Calendar year (calendar year)
1, upper limit 19000 ~ 20000 m w "
2. The maximum horizontal flight Mach number is 2. 1 ~ 2.2. {
60 1 Imagine 1967 to complete the first flight of the J-8 aircraft, 1970 can equip troops in small batches. In the following time, the J-8 aircraft was quickly approved and the specific trial production schedule was determined. a & ampZ3V/
Although the J-F has selected eight schemes, considering the need of technical reserve, it also considers providing another possible option for the troops. The Third Engine Department decided to develop the J-8 fighter and carry out technical demonstration of new single-engine fighter, turbofan engine and medium-range air-to-air missile in a small scope. /6w
1965 April 12, No.3 Machinery Department officially issued the Notice on Developing the Scheme Design of the J-9 Aircraft to 60 1, requesting two aspects of the scheme to be demonstrated and compared, and one of them was selected as the final draft of J-9: n! book
1, outstanding sniper performance, giving consideration to interception operations and dealing with low-altitude and high-speed targets. The maximum Mach number is about 2.3, the ceiling is about 20,000 meters, the voyage is longer, and the combat radius is more than 450 kilometers. E
2. Highlight interception performance and give consideration to combativeness. The maximum Mach number is 2.4 ~ 2.5, the ceiling is 2 1 ~ 22km, and the operational radius is 350km. " Yr
The total weight of the aircraft is required to be controlled at about 14 ton. z*r
On April 1966, 1, the Third Machinery Division submitted the design scheme of the J-9 aircraft to the Office of National Defense Industry and the Commission of Science, Technology and Industry for National Defense. The Commission of Science, Technology and Industry for National Defense held a meeting to review the design scheme of the J -9 aircraft, and submitted a report on the tactical and technical demonstration of the J -9 aircraft to the Military Commission. After reviewing the two schemes, the Central Military Commission finally decided to develop the J -9 aircraft according to the first scheme, and made some changes to the design indicators: the maximum Mach number is 2.4, the ceiling is 2 1000m, the maximum climb rate is 200m/s, the maximum range is 3,000m, the operational radius is 600km, and the endurance time is 3 hours. S \ c
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As mentioned earlier, the J-9 was designated as a major modification of MIG-2 1 at the beginning of the design, and its technical inheritance was obviously lower than that of J-8 adopting the "gradual modification" scheme, which not only improved the performance of the aircraft, but also greatly increased the difficulty of aircraft development. What's more, during the development of the J-9, the military's performance requirements were changed again and again, forcing the R&D department to revise the design plan again and again, which is normal for J-9. . ? n[
According to the initial development requirements of J-9, the aerodynamic layout parameters of J-9 were selected from1965,601,and four wing plane shapes, namely 2q, were selected.
1, swept wing with leading edge swept back 50 degrees? ge
2. Delta wing 1i6 swept back 57 degrees.
3. The swept wing Rt2eKX with the leading edge swept back 55 degrees.
4. Double delta wing with double leading edge and sweep angle = 365.
60 1 made models of four wing plane shape schemes and carried out wind tunnel experiments. 4_
Among them, swept wing or delta wing is mainly considered, and both swept wing and delta wing adopt the method of leading edge swept back to increase the critical Mach number of the wing. However, if supersonic flight increases to Mach 2.0, the leading edge sweepback angle must be greater than 60 in order to adopt subsonic swept wing scheme. However, if the leading edge sweepback angle is too large, the stress on the wing root structure will deteriorate and the structural weight will increase; In addition, at low speed, the aerodynamic characteristics will also deteriorate, the lift will decrease and the drag will increase, which will directly affect the maneuverability of the fighter, so it is not suitable to use large swept wings. Delta wing is suitable, which not only has the advantages of swept wing, but also can ensure the stress state of the root structure and reduce the weight of the structure, which is helpful to ensure the longitudinal flight stability of the aircraft. Therefore, 60 1 eliminated the first three schemes, and changed the leading edge sweep angle of delta wing to 55 degrees, which is called 歼 9 IV scheme. yj6！ X
○ 9 IV scheme is a delta wing scheme with normal layout. Except that the nose is changed to air intake on both sides, the rest are the same as 07 and 08. The aerodynamic shape is similar to that of FC- 1 early model?7cp, but the size is much larger. It can be regarded as two sides of MIG -2 1. Because this scheme has not made any major changes to MIG -2 1, the success is quite certain. ! 1hQ
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○9 Four-scheme Imagination Diagram j{(WR
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However, from the fourth quarter of 1966 to the beginning of 1967, it was found that the 歼 9 IV scheme was not ideal, so the tailless delta wing scheme was put forward, which was called V scheme. The V scheme is a tailless delta wing aircraft with air intakes on both sides, which is somewhat similar in appearance to the famous French Mirage fighters. The aircraft uses delta wings, with a leading edge sweepback angle of 60 degrees and a wing area of 62 square meters. Because the wing area is extremely large, the wing loading is correspondingly reduced, and the maneuverability of V scheme is obviously improved compared with that of IV scheme. However, it is difficult to solve the problems such as the stiffness and control force of aileron and the control difficulty caused by zero lift torque. {`; P
During this period, as a direct competitor of J-9, J-8 developed smoothly. At the end of 1966, 60 1 completed all the drawing design work. In August, 1 12 factory started the trial production of two prototypes. 1In June, 1968, the final assembly of the J-8 fighter 0 1 prototype was completed. 65438+February 19, the first ground taxi was completed. Although the front wheel shimmies seriously during taxiing, the left main wheel tire bursts during emergency braking. However, on July 5th, 1969, the 歼 8 was still driven by test pilot Yin Yuhuan, and the first test flight of this route was completed at 1 12 factory, which lasted for 30 minutes. During the test flight, the flight altitude was 3000 meters and the speed was 500 kilometers per hour. |a
Under the interference of the "Cultural Revolution", the development of both engines came to a standstill. ;
1968 In March, the Sixth Hospital held a meeting on "Mobilizing and Implementing the Development Task of the J-9 Aircraft", decided to adopt the V scheme, and proposed to strive to send the J-9 into the sky before the 20th anniversary of the 11th National Day of 1969 as a gift for the 20th anniversary of the National Day. Because some technical problems of V scheme are difficult to solve, and domestic production cannot be carried out normally due to sports, V scheme has not been carried out, and the Sixth Hospital instructed to stop the trial production of V scheme. K=ZNm
February 3 1969, 60 1 Decided to spare some strength to continue the development of the J-9 aircraft. 19691June 10, the aviation industry leading group decided to continue to develop the 歼 9, and decided to trial-produce the delta wing scheme with air intake on both sides, that is, the 歼 9 IV scheme, and arrange the trial-production work in 1 12 factory (Shen Fei)./kloc. =R[H
At that time, the 1 12 factory was fully resuming the research and development of the 歼 8. 19691October 30th, according to the actual situation, the Military Management Committee of No.3 Machinery Department and No.6 Hospital decided to set the trial-production task of J-9 at 132 Factory (Chengdu Aircraft Company). ：
On May 4th, 1970, 60 1 dispatched more than 300 people to Chengdu Air Force Aviation School 13 (later established as 6 1 1) for the trial production of the J-9 aircraft. “q^Q
1On June 9, 1970, the aviation industry leading group held a special meeting in Beijing, reviewed the J-9 scheme, and put forward higher requirements for the performance index of J-9: the movement radius is 900 ~1000km, the weight13t, the overload is 8g, the ceiling is 25000m, and the flight Mach number is 2.5. The so-called "double 25" scheme. x & lt
1970165438+10, the Sixth Hospital held a meeting of leading cadres in Xi 'an. Air Force leaders put forward new requirements for the J-9 being developed: "Double 25 is too small and double 28 is too high, so it should be double 26, that is, the maximum use Mach number is 2.6 and the static ceiling is 26 kilometers". v8
The original layout of J-9 can't meet this new requirement, and the aerodynamic layout needs to be redesigned. P~
After repeated design-selection-evaluation-elimination process, China designers finally chose the duck layout and air inlets on both sides for the J-9, which is the so-called J-9VI scheme. x
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○9vi scheme Imagine Figure 2=dV
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This is a bold attempt. You know, Sweden's Saab -37 Thunder Fighter, the world's first practical fighter with a duck layout, really came into service at 197 1. That is to say, when China chose the J -9VI scheme, no fighter plane in the world had adopted the canard layout. +2
○9VI scheme fully embodies the innovative spirit of aviation researchers in China. But at the same time, the change of design scheme also reflects the blindness and dryness of China aviation industry in the early exploration process! Sasazawa
Although the problem of aerodynamic layout has been solved, after a period of time in the 歼 9VI scheme, it was found that the upper limit index determined by the "Double 26" standard was still too high, and the performance of the selected turbofan 6 engine could not meet the requirements, so nine aircraft were developed and stranded again. $`
1975 65438+ 10/0, No.3 engine department reported to the State Council and the Central Military Commission with document No.8 of the Third Hospital (75). It is hoped that the index of the J -9 will be appropriately reduced, that is, the maximum Mach number will be kept at 2.5 ~ 2.6, the ceiling will be reduced to 23,000 meters, the maximum climb rate will be 220 meters per second, the basic range will be 2,000 kilometers, and the operational radius will be greater than 600 kilometers. 0
18 In February, under the personal intervention of Comrade Deng Xiaoping, who was in charge of the State Council's work at that time, the State Council and the Central Military Commission issued Guo Fa (1975) No.34 document, agreeing to continue to develop the J-9 aircraft according to the adjusted indicators. Leviticus (Leviticus)
197565438+On February 23rd, the State Planning Commission and the the State Council National Defense Industry Office approved the development and implementation plan of the J-9 aircraft reported by the No.3 Machinery Department with the document (75) Gong Ban Zi No.395, and agreed to trial-produce five aircraft in zero batches, with the first aircraft 1980 finalized and 1983 allocated 400 million yuan in principle.
1At the beginning of 976, 6 1 1 further adjusted the overall aerodynamic layout and design parameters of the 歼 9 on the basis of the 歼 9VI scheme, and formed the 歼 9VI-II scheme. n0SQtW
The main features of the plan are
1. Aerodynamic layout: the layout design of the aircraft keeping duck χ 9VI. The main wing is a 60-degree delta wing with a wing area of 50 square meters, and the canard wing is a 55-degree delta wing with a fixed installation angle of 3 degrees and an area of 2.58 square meters. & amp^}:
2. Air intake mode: air intake from both sides is adopted, and the air intake is binary adjustable multi-wave system mixed compression type. 4> If
3. Engine: Install turbofan 6 engine, with full afterburner static thrust on the ground 12400 kg. & lt high pressure
4. Radar system: The aircraft is equipped with 205 radar, with a detection distance of 60-70km and a tracking distance of 45-52km. ! Q $ no
5. Main weapons: four PL-4 interceptor missiles, which are divided into two types according to the seeker-semi-active radar PL-4A with maximum range 18km and passive infrared PL-4B with maximum effective range of 8km. " Xt#u
Judging from these final design indicators, the J-9 has the ability to compete head-on with early third-generation fighters such as F- 14. In a sense, the J-9VI-II is the first domestic fighter independently developed by China that meets the international third-generation jet fighter standard. . Dollar)
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Fourth, the strength has not been caught. Half Wave
Although the proposed 歼 9vi-Ⅱ scheme has solved the aerodynamic layout problem that has puzzled the aircraft for a long time, judging from the actual development capability of China jet fighters at that time, the design idea is 歼 9 scheme, especially 歼 9vi-Ⅱ scheme, which is too avant-garde. Although 歼 9vi-Ⅱ undoubtedly greatly surpasses its half-brother 歼 8 scheme, it has encountered insurmountable difficulties in the development process. ` =b
In 1978, the development of 歼 9 began to shrink due to the urgent requirements of the design and drawings of major reconstruction that 歼 7 should be undertaken by 6 1 1. 1980, in order to implement the national economic adjustment policy, the R&D of J-9 was completely suspended, and the R&D expenditure was about 2 1.22 million yuan. Like the later Qiang -6, J-9 finally drew an unsatisfactory end in the history of aviation development in China.