The controversy over the U.S. sixth - generation fighter F - 47 continues. In recent days, the focus of the controversy has centered on the aerodynamic design of the F - 47 fighter. After all, the aerodynamic design of the F - 47 is really too strange, almost exceeding all imaginings of a sixth - generation fighter. For example, looking at the wing airfoil of this aircraft, since the end of World War II, almost all fighters have their wings installed horizontally, with no or only a slight dihedral angle. However, the wings of the F - 47 fighter have a huge dihedral angle, even greater than 40 degrees. This makes the wings of the aircraft more similar to the gull wings used by the famous F4U Corsair fighter produced by Chance Vought for the U.S. Navy during World War II. Needless to say, this appearance looks both strange and ugly.
Another example is the design of the nose section of the F - 47 fighter. The nose of the aircraft is square. Currently, the shape of the air intake is unclear. It is speculated externally that it may use a belly - intake design. This nearly square and flat - looking nose is considered by some to be beneficial for reducing the lift - to - drag ratio at supersonic speeds, similar to the nose design of some other aircraft. The problem is the same: the design is too strange. Many military enthusiasts believe that the X - 32 fighter has made a comeback in Boeing's sixth - generation aircraft.
There is also a controversy about whether this aircraft has vertical tails. Although in the publicly - released imaginary picture of the F - 47 fighter, there are no vertical tails, some experts have found that in the imaginary picture (or is it a photo?) of this aircraft, there are inexplicably two extra shadows in the vertical tail area. Other than vertical tails, there seems to be no other possibility for these two extra shadows. Referring to the preliminary design of the NGAD project by Raytheon, some people think that the U.S. sixth - generation aircraft may still have vertical tails.
Of course, the most astonishing thing is the canards on the F - 47 fighter. For years, Western military experts and their followers at home have been busy arguing that canards are not stealthy. From the early quip of the U.S. Air Force - "The best canards should be on the enemy's aircraft" (mainly due to insufficient understanding of the lift - increasing effect of canards and poor flight control at that time) to various arguments that canards do not have good low - detectability performance because of the gaps... Now, all these criticisms have come back like a boomerang. Even Western military experts don't know how to defend it suddenly. Some say that with the development of technology, using wave - transparent materials can ensure the stealth of canards. Others say that since other countries have used canards, it doesn't seem like a big deal for the U.S. to use them. Of course, the wittiest remarks come from Chinese netizens. They say that our canards are canards, while the U.S. has "eagle wings". Since "eagle wings" are more advanced than canards, they must be stealthy. They also say that as long as the canards of the empire have the addition of "democracy", they are surely stealthy, while canards of other countries, well, forget it... There are endless jokes.
Why was the F - 47 fighter designed like this? What are the reasons for these strange designs? There are two factors. Firstly, the F - 47 fighter that has emerged this time may still have room for further improvement. Looking at the concept design drawings of the NGAD that have been leaked by several major U.S. aircraft manufacturers in recent years, there are all kinds of strange designs. For example, the earliest plan of Lockheed Martin had a large flying - wing design similar to our new - generation combat platform, with a reported fuselage length of up to 73 feet. In 2017, Raytheon used digital twin technology to generate a concept design of the NGAD, which looked surprisingly similar to the J - 20 fighter. In addition, concept designs similar to some other sixth - generation aircraft, and even designs similar to the Wuzhen - 8 in appearance, have also emerged one after another in the development history of the U.S. NGAD fighter program. According to the public statement of a certain figure, Boeing's F - 47 fighter started the first flight of a technology demonstrator five years ago. These so - called technology demonstrators may not necessarily be full - scale aircraft, and may even be scaled - down models. Currently, although the F - 47 fighter already has an official model number, in fact, an Engineering and Manufacturing Development (EMD) contract has been signed. The so - called EMD contract means that the aircraft has completed the technology verification and started to manufacture the prototype. That is to say, it has just entered the detailed design stage. The project process includes detailed design, design drawing release, process drawings, prototype manufacturing, and the first flight of the prototype... After the first flight of the prototype, the early production of the mass - production prototype begins. The U.S. Air Force and Boeing have promised to present a prototype to a certain person in 2028, but currently, the basic detailed design of this aircraft has not even started. Since the detailed design has not been carried out, there is still room for improvement in the overall configuration. Maybe after the aircraft enters the detailed design stage, the canards and vertical tails that appear in the imaginary picture will be directly cancelled.
The second factor: Why is Boeing's F - 47 fighter designed so strangely, with the unprecedented gull wings and vertical tails? All sixth - generation aircraft face the same design problem, which is the issue of directional stability. After all, the directional stability of an aircraft requires the cooperation of vertical tails and ventral fins. An aircraft without directional stability will be in an uncertain state of rolling or sideslipping around the axis when affected by cross - winds. Especially in the case of low - altitude penetration or when the aircraft is about to land, the lack of directional stability can cause great harm to flight safety. So, ensuring the directional stability of a sixth - generation fighter is a difficult problem. For example, for our new - generation combat platform, it is believed that its directional stability performance during high - altitude flight is mainly compensated by powerful flight control performance. At the same time, multiple flaps and ailerons are used for differential control to automatically adjust the rolling tendency of the aircraft caused by cross - winds. As for the sideslipping tendency, it may be compensated by thrust - vectoring engines. In the low - altitude and low - speed phase, especially during take - off and landing, the aircraft needs to open the slotted flaps on both sides of the wingtips. From the design of these two flaps, they can not only be used as speed brakes, but also have a certain inclination angle. To some extent, they can play the role of vertical tails, and since they are located at the wingtips, the control arm is relatively large, which has a good effect on directional stability. As for another new - generation combat platform, more measures have been taken to ensure the aircraft's directional stability. It definitely has a thrust - vectoring engine, and there is a rather large depression designed on the fuselage belly. This depression, in a sense, acts as a flow - guiding trough and can also improve the aircraft's directional stability. During the landing phase, this new - generation combat platform uses radical full - moving wingtips to act as vertical tails.
Obviously, the problem of directional stability of sixth - generation aircraft is also the same for the U.S. Compared with our design choices of using thrust - vectoring engines, using flight control to adjust the control surfaces at high - altitude and high - speed, using full - moving wingtips or slotted flaps at low - altitude, and setting flow - guiding troughs on the fuselage belly of some models to maintain directional stability at the expense of a little low - detectability performance, Boeing's approach seems much simpler and more straightforward. It directly uses a wing dihedral angle installation, adopting a design similar to gull wings. After the main wing has a dihedral angle, to some extent, the main wing of the aircraft can play the role of a vertical tail in terms of directional stability. At the same time, it seems that a flow - guiding trough is also set on the fuselage belly (judging from the previous design concept drawings). As for the vertical tails, if the F - 47 fighter does have vertical tails, it can only be said that Boeing really has no confidence in ensuring the aircraft's directional stability and has used multiple means to ensure it. After using so many ways to enhance the aircraft's directional stability, and still adding a pair of canards to the aircraft, the only possible result is that Boeing may have set a very wide static instability for the F - 47 fighter. Using canards can maximize the lift - increasing effect of canards and improve the aircraft's maneuverability and agility. However, setting the static instability too wide may cause the aircraft to yaw and sideslip. Therefore, it can only be compensated aerodynamically, which is why so many means have been used to ensure the aircraft's directional stability. It can only be said that Boeing's design choices are really hard to comment on. As for the canards themselves, there is not much to say. Whether it is the canards of the J - 20 fighter or those on the U.S. F - 47 fighter, they will have a certain impact on the low - detectability performance. So, we can see that the canards of the J - 20 are not directly facing the main combat axis. Instead, a certain outward - expanding arc is used to shield the front shaft and the shaft gap of the canards, trying to ensure that the radar electromagnetic waves from the main threat direction will not irradiate the gap between the canards and the fuselage. However, even so, if the radar waves come from the side of the main threat direction, it will still cause relatively obvious reflection. That's why in the sixth - generation aircraft, we have all given up the canards to ensure the all - directional low - detectability performance of the aircraft. And the design that we have abandoned, the U.S. has now picked up. Moreover, the F - 47 fighter seems to have both canards and vertical tails. It can only be said that the U.S. has really been hasty in pushing out the F - 47 fighter in order to meet the schedule... Let's see what the aircraft will look like in the end. If it really has both canards and vertical tails, we can only say that the F - 47 fighter can be called the Su - 57 of the sixth - generation aircraft era, which would be really funny.
