Chapter 1354

The reason why the aerodynamic layout similar to the flying wing mode is the optimal solution is that the lift coefficient and space utilization ratio of this aerodynamic layout are the highest among all start-up layouts.

Let's talk about the lift coefficient first. The flying wing layout belongs to the full lift complex, and the airframe and wing belong to the integrated layout, which breaks the previous boundary of wing body integration and achieves the perfect unity. Because of this, the overall lift coefficient is very high, which ensures the basic dynamic ability of the whole aircraft.

In addition to the space utilization rate, the high space utilization rate of flying wing layout is recognized by the industry, which can be seen from the fact that the B-2 stealth bomber's overall size is only half of that of B-52, and its range and missile carrying capacity reach more than 70% of that of B-52.

If you put it on other aircraft models, this super-high space utilization rate is not much. It's not the same when you put it on VTOL, because in addition to the traditional high-speed aero-engine, VTOL also has a lift fan at the rear of the cockpit.

No matter how to optimize and how to reduce weight, the huge space occupancy is equivalent to completely hollowing out the middle of the VTOL, balancing the transmission shaft and the air ducts on both sides of the wing on the VTOL, and occupying more than 30% of the space on the VTOL fuselage.

Naturally, the combat aircraft moving towards these spaces will have to reduce their fuel and missile loads correspondingly, and even compromise their flight performance. Not only will the aircraft not be able to go up to the sky.

At this time, the aerodynamic layout of China's take-off similar to the flying wing mode is high, and the space utilization rate is highlighted.

Even if a lift fan with a diameter of 1.8 meters is installed in the rear of the cockpit, and the transmission shaft and air duct are arranged inside, the flying wing layout can perfectly contain these equipment with its huge utilization space. At the same time, it still has objective fuel load and external weapon loading capacity.

You should know that the length of China's VTOL verification aircraft is 17.6 meters, the wingspan is 13.2 meters, and the wing area reaches 78.4 square meters. Such a huge wing area naturally becomes the best storage space for the built-in fuel tank. Coupled with the thick middle fuselage, the fuel capacity is guaranteed.

The huge wing area not only improves the internal space, but also the wing load, which is very important for weapon loading. Due to the unique design of flying wing layout, the missile load is also guaranteed.

With sufficient fuel, excellent pneumatic layout and sufficient ammunition, if there is no excellent aero-engine to support, all previous efforts will be in vain.

As the saying goes, if we want to achieve the 1:1:1 ratio of empty weight, fuel load and missile load, the engine performance must be strong, at least the thrust must be particularly large, otherwise it will not be able to support the basic performance of the whole aircraft.

In addition, the aeroengine on the VTOL must also have excellent fuel economy. Otherwise, an oil tiger with the same fuel consumption as water, not to mention 6.2 tons of fuel, can't even double the combat radius.

Of course, the most important thing is the limitation of the single engine system. After all, the VTOL combat aircraft only adopts the single engine layout. If it adopts double engines, the complexity will soar exponentially, which is not cost-effective.

The problem is that in addition to thrust and fuel economy, the most important thing for single engine is safety, which requires that the aero-engine must be well manufactured and stand the test.

Therefore, high thrust to weight ratio, excellent fuel economy and far more safety factor than ordinary aeroengine become the first choice of VTOL combat aircraft.

This is also the most frustrating technical difficulty of this type of aircraft.

Otherwise, all countries in the world will know the advantages of VTOL fighters. Especially in Europe during the cold war, when the Soviet Union's artillery and missiles washed the ground, the combat aircraft may not have the chance to take off at the airport runway. At this time, the tactical advantages of non picky VTOL fighters will be highlighted.

The question is, after so many years, how can the United Kingdom and the Soviet Union, together with the United States, which has dug a wall from the United Kingdom, have the ability to develop and produce VTOL fighters, but other countries have not even entered?

It's not how difficult the aerodynamic layout and technical design are, but the key is that the high-level aeroengine keeps 99% of the countries out of the threshold of this kind of aircraft.

For example, France, as early as the late 1960s, devoted itself to the development of vertical take-off and landing fighter planes. To this end, it specially refitted several test verification planes on the basis of mirage III fighter planes. As a result, the engine failed to pass the standard, and the arrogant Gallic chicken was not willing to bow down to John Bull to subscribe for "harrier" technology, However, they were unable to face the consequences of the Soviet Union's comprehensive firepower. In the end, there was no way to make up for the number simply by creating a phantom F-1 that could implement short-range take-off and landing on high-grade highways.

Even the French, who have a solid foundation in aviation technology, are very weak in this respect, let alone other countries.

It is reasonable to say that China Tengfei, whose technology accumulation is not as good as that of its French counterparts, also does not have the ability to impact such high-level aero engines. It is not even clear how this kind of engine is going on and how to develop it. This is also the fundamental reason why Tengfei group revealed that it wanted to develop VTOL verification aircraft in the late 1980s.

However, what's surprising is that the Soviet Union disintegrated in the early 1990s, and a large number of Soviet aviation production and development units were forced to the market, and then the European and American aviation giants almost plowed the Russian leek roots with their sickles.

At that time, Tengfei group timely acquired Yakovlev Design Bureau, which was on the verge of bankruptcy. It not only acquired the technology of Jacques-141 vertical take-off and landing fighter, but also obtained the samples and some technologies of r-79-300 vector turbofan afterburner engine.

Originally, there was a certain accumulation of China's take-off in the field of aero-engine. With these things, it was equivalent to having the key to turn on the special power of vertical take-off and landing fighter, so it soon started to imitate and set up a very take-off system code named wd-64ml turbofan engine.

The performance index is basically the same as that of r-79-300 vector turbofan afterburner engine, with cruise thrust of 15.6 tons and afterburner thrust of 19.7 tons.

However, in addition to the thrust data of the two eyes, the wd-64ml turbofan engine has been pulled in other aspects. Firstly, the bypass ratio is too large, reaching 0.81, which leads to the engine diameter is too large, which seriously occupies the aircraft space. At the same time, the thrust efficiency is not high.

Secondly, the temperature in front of the turbine is too low, which is only 1620 Kelvin, that is, 1346 ℃. This temperature is much lower than that of the advanced military engines in Europe and the United States, even compared with the 1600 ℃ temperature in front of the turbine of China's take-off wd-60 series Aero Engines.

Affected by the low temperature in front of the turbine, the thrust to weight ratio of wd-64ml turbofan engine is very low, only 5.46, which is on the same level as the "Spey" engine used in fbc-1 fighter bomber.

In other words, the Russian r-79-300 is far behind the advanced engines in other aspects except thrust, so it is difficult to adapt to the future operational requirements.

Unfortunately, the Russians don't seem to think that their r-79-300 is a drag. On the contrary, they have heard that China's r-79-300 engine has been imitated and pasted like a dogskin plaster. They have to charge a patent fee for it.

Originally, I didn't think the r-79-300 was very good. In addition to the Russian's confusion, China's take-off simply gave up imitation and began to upgrade itself.