The reason why an aerodynamic layout similar to the flying wing mode is the optimal solution is for no other reason than the lift coefficient and space utilization of this aerodynamic layout are the most efficient among all startup layouts.
Let¡¯s talk about the lift coefficient first. The flying-wing layout is a full-lift complex, and the body and wings are integrated layouts, breaking the previous boundaries of wing-body fusion and achieving perfect unity. Because of this, the overall lift coefficient is extremely high. This ensures the basic maneuverability of the entire aircraft model.
Let¡¯s talk about space utilization. The flying wing layout is recognized in the industry as having a high space utilization rate. This is because the b-2 stealth bomber has a range and bomb load of up to the b-52 even though its overall size is only half of the b-52. This can be seen above the 70% level.
If placed on other aircraft models, this ultra-high space utilization is nothing, but it is different when placed on a vertical take-off and landing verification aircraft, because in addition to the traditional high-speed aero engines, the vertical take-off and landing verification aircraft has A lift fan is also installed at the rear of the cockpit.
No matter how it is optimized or how much weight is reduced, the huge space occupied is equivalent to completely hollowing out the middle part of the vertical take-off and landing verification aircraft. The straight transmission shaft on the aircraft and the air ducts on both sides of the wings play a balancing role. Every inch of the aircraft is precious. More than 30% of the space on the body is occupied by these vertical take-off equipment.
Combat aircraft heading towards these spaces will naturally have to reduce their fuel and bomb loads accordingly, and even compromise on flight performance. Not only will the aircraft not be able to fly into the sky.
At this time, China Tengfei¡¯s aerodynamic layout similar to the flying wing model highlighted its high space utilization.
Even though a lift fan with a diameter of 1.8 meters is installed at the rear of the cockpit, and a drive shaft and air duct are arranged internally, the huge utilization space inside the flying wing layout can perfectly accommodate these devices, while still having Objective fuel load and external weapons stowage capability.
You must know that China Takeoff's vertical takeoff and landing demonstration aircraft has a length of 17.6 meters, a wingspan of 13.2 meters, and a wing area of ??78.4 square meters. Such a huge wing area naturally becomes the best storage space for the built-in fuel tank. In addition, The thick middle fuselage ensures the fuel capacity.
The huge wing area not only increases the internal space, but also the wing load, which is crucial for weapon mounting. Due to the unique design of the flying wing layout, the bomb load is also guaranteed.
With sufficient fuel, excellent aerodynamic layout and sufficient ammunition, if there is no support from an excellent aero engine, all the early efforts will be in vain.
As the saying goes, great power works wonders. If you want to achieve a ratio of empty weight, fuel load, and bomb load of 1:1:1, the performance of the engine must be powerful, and at least the thrust must be extremely large, otherwise it will not be able to support the entire aircraft. Basic performance.
In addition, the aeroengine on the vertical take-off and landing verification aircraft must also have excellent fuel economy. Otherwise, if it is a gas tiger that consumes as much fuel as water, let alone 6.2 tons of fuel, it will be twice as much. The combat radius cannot be increased either.
Of course, the most critical thing is the limitation of the single-engine system. After all, vertical takeoff and landing combat aircraft can only use a single-engine layout. If dual-engines are used, the complexity will increase exponentially, which is not cost-effective.
The problem is that if a single-engine engine is used, in addition to thrust and fuel economy, the most important thing is safety. This requires that the aeroengine must be well-made and withstand the test.
Therefore, the large thrust-to-weight ratio, excellent fuel economy and safety factor far exceeding that of ordinary aero engines have become the first choice for vertical take-off and landing combat aircraft.
And this is also the most maddening technical difficulty of this type of model.
Otherwise, all countries in the world know the benefits of vertical take-off and landing fighter jets. Especially during the Cold War, Europe was faced with the threat of Soviet artillery and missiles sweeping away the ground. Combat aircraft may not have the chance to take off from the airport runway at all. At this time, those who are not picky about vertical take-off will The tactical advantage of dropping fighter jets is highlighted.
The problem is that after so many years, why is it that only the United Kingdom and the Soviet Union, plus the United States poaching from the United Kingdom, have the ability to develop and produce vertical take-off and landing fighter jets, but other countries have not even started?
It¡¯s not how difficult the aerodynamic layout and technical design are, the key is that high-level aero engines block 99% of countries from the threshold of this type of aircraft.
For example, France was committed to developing vertical take-off and landing fighter jets as early as the late 1960s. To this end, it specially modified several experimental verification aircraft based on the Mirage 3 fighter jets. As a result, the engine was not up to par and problems occurred frequently, and it was proud of it. The Gallic chickens were unwilling to bow their heads to John Bull and subscribe to the "Sea Harrier" technology, but they were unable to face the consequences of the Soviet Union's comprehensive firepower. In the end, they were unable to simply come up with a short-circuit system that could be used on high-grade highways. The Phantom taking off and landing is f-1 away to make up the number.
????????????????????????????????????????????????????The powerful French are failing in this area, let alone other countries.
It stands to reason that China Tengfei, whose technological accumulation is not as good as that of its French counterparts, does not have the ability to impact this type of high-level aero-engine. It even does not know what this type of engine is, and how to finalize its development. This is why in In the late 1980s, after Ascendas Group revealed that it wanted to develop a vertical take-off and landing demonstrator, the industry was generally not optimistic about the fundamental reason.
However, the twist of fate is that the Soviet Union disintegrated in the early 1990s. A large number of Soviet aviation production and development units that were unable to make a living were forcibly pushed to the market. Then, European and American aviation giants carried a sickle and almost destroyed the Russians over and over again. The roots of the leeks were peeled off.
At that time, Ascendas Group made a timely move and fully acquired the Yakovlev Design Bureau, which was on the verge of bankruptcy. Not only did it acquire the technology of the Yak-141 vertical take-off and landing fighter, it also acquired the supporting R-79-300 vector turbofan afterburner The engine samples and part of the technology were obtained.
China Tengfei, which originally had a certain accumulation in aviation engines, had the key to unlocking the special power for vertical take-off and landing fighter aircraft, so it quickly started to imitate it and gave it a very Tengfei series code name wd. ¡ª64ml turbofan engine.
The performance indicators are basically the same as those of the R-79-300 vector turbofan afterburner engine, with a cruise thrust of 15.6 tons and an afterburner thrust of 19.7 tons.
However, in addition to the thrust data of the two eyes, the wd-64ml turbofan engine has limitations in other aspects. First, the bypass ratio is too large, reaching 0.81, which results in the engine diameter being too large and seriously occupying the aircraft space. The thrust efficiency is not high either.
Secondly, the temperature in front of the turbine is too low, only 1620 Kelvin, which is 1346 degrees Celsius. This temperature is not to mention compared with advanced military engines in Europe and the United States, but is also compared with the 1600 degrees Celsius temperature in front of the turbine of China's Tengfei WD-60 series aero engines. A lot lower.
Affected by the low temperature in front of the turbine, the thrust-to-weight ratio of the wd-64ml turbofan engine has become extremely low, only a pitiful 5.46, which is at the same level as the "Spey" engine used on the FBC-1 fighter-bomber. .
In other words, apart from thrust, the Russian R-79-300 has a huge gap with advanced engines in other aspects, making it difficult to adapt to future combat needs.
"It's a pity that the Russians don't seem to think that their R-79-300 is a stretch. Instead, after hearing that China's Tengfei copied their R-79-300 engine, they put it on like a dog-skin plaster and charged royalties for life and death.
???????????????????????????????? did not think the r-79-300 is so good, coupled with the Russians' self-awareness, China Tengfei simply gave up imitation and directly started its own upgrade.
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