Overview of flying wing development

In the traditional aircraft design, the center of gravity of the aircraft is always located in front of the lift center of the wing, which makes the lift provided by the wing break the balance of the fuselage, and the aircraft is easy to cause the nose to dive downward. In order to balance this trend, some small control wings with downward force are usually designed at the tail of the aircraft to offset the dive trend of the aircraft. The basic principle is that the plane can fly freely at a certain angle. When the power decreases, the speed decreases, the wing lift decreases, the nose naturally decreases, and then the plane begins to descend.

There are many obstacles for a simple and safe plane. The control wing located on the tail wing of an aircraft often makes the aircraft longer than the actual length, and most of these lengthened fuselage can not bear the balanced load. In addition, the existence of the control wing will increase the resistance and reduce the overall performance of the aircraft. The biggest problem is that these wings increase the resistance and weight of the aircraft at the same time, which makes the aircraft engine have to provide extra thrust to generate more lift than the original aircraft needs.

The traditional layout of aircraft-the load is in front and the wing surface is behind-will also cause another problem, that is, the wing will bend (deflect) backwards, so sometimes the wing will be in front of the center of gravity, and sometimes it will be behind it. The stability of the aircraft is as important as the controllability (through the extra wing surface). However, without additional control wings, the resistance and weight can be reduced. In most cases, this can significantly reduce flight resistance, and designers can concentrate on solving stability problems.

The only disadvantage of flying wing is that in order to hide the fuselage in the wing, the wing of the aircraft must be designed to be much thicker than the usual wing. It doesn't matter at low speed, but when the plane approaches the speed of sound, it will produce a huge drag effect in the relatively thick part of the wing, so the flying wing is not suitable for high-speed aircraft and is more sensitive to drag than ordinary aircraft. In addition, there will be a series of stability problems at high speed, such as "Mach drop", which need designers to solve through a lot of efforts.

For these reasons, the study of flying wing is limited to the period from 1930 to 1940. At that time, flying wing was considered as a natural solution to produce large passenger planes, which could also carry enough fuel for regular transatlantic flights with the same passenger capacity. Flying wing's huge internal volume and low resistance make it play this role naturally. Jack Northrop in the United States, Alexander Justus von Liebig and the Short brothers in Germany all have research in this field, while Hugo Juncker in Germany obtained a concept patent for a flying wing glider at 19 10.

Juncker started his great JG 19 19 year, trying to put passengers in thick wings. However, at 192 1, the Joint Air Traffic Control Committee announced that the unfinished JG 1 aircraft had broken the size restrictions on German aircraft after World War I, and Juncker's futuristic flying wing could accommodate 1000 passengers at most, and the most successful one was193/kloc-. The cockpit is located at the leading edge of the wing and embedded in the wing. At that time, the largest land plane (relative to seaplane), the G-38 nicknamed "Flying Hotel" joined Lufthansa's fleet, and later it was turned into military service until 194 1 was destroyed by the British troops retreating from Athens. Japan was authorized by Junker to build several G-38s as bombers.

Many German military aircraft designed in the late World War II were based on flying wings or modified on this basis to maximize the range of jet engines. The most famous is the first flight of Gotha Go-229, 1944. It not only combines the concept of flying wing (Nürflugel), but also hides two jet engines in the composite wing, which can absorb radar waves. Now the prototype of this plane is still preserved in its original state by the Smithsonian Museum. In 2008, the model made by Northrop Glaiman showed that Ho 299 was discovered by the British radar system at that time.

After the war, many conceptual designs were based on the plane shape of the plane, but problems soon appeared. In order to extend the bomber's voyage, the interest in flying wings continued until the 1950' s. Northrop B-49 bomber was its last swan song, but it was not put into production in the end, and even the flying wing design could not make up for the requirement of oil loading. Later, a larger ordinary plane similar to Boeing B-52 bomber was built to replace the flying wing design. Subsequent long-range bombers never took the form of flying wings until the emergence of the B-2 ghost stealth strategic bomber.

In the1980s, flying wing, as a way to greatly reduce the radar reflection signal, once again attracted people's attention, which eventually led to the emergence of Northrop's B-2 ghost stealth strategic bomber. In this project, excellent aerodynamics is not the key issue.

Because the flying wing can still maintain excellent performance in the middle and low speed range, its idea of being a tactical transport aircraft has never been interrupted. Boeing has been conducting research on the project of adopting wing-body fusion transport aircraft, which is similar in size to Lockheed C- 130 Hercules transport aircraft, with longer range and additional load of 1/3. Boeing, McDonnell Douglas, De haviland and many other companies have considered designing flying wing passenger aircraft, but so far they have not realized it. The problems of passenger aircraft using this design include comfort (except for the middle seat, there will be too much inclination when turning), too few windows, high difficulty in escape, and the need to change the airport design.