The "flying wing" scheme has long attracted aircraft manufacturers and developers of unmanned aerial vehicles, both in our country and abroad. To date, foreign countries have created a number of curious UAVs of similar architecture, differing in one way or another. Let's consider the main examples of such a technique and its characteristic features.
A full range of
Many countries are currently engaged in the development of UAVs of different classes, incl. previously did not have a developed aviation industry. As a result, there are a large number of types of drones of different schemes, classes and tasks on the market and in parts. The flying wing sphere is also in line with these trends - there are developments in all major classes.
However, there is a certain bias. Thus, the “flying wing” scheme is not very popular abroad in the field of light and ultralight military UAVs. The most famous and successful developments of this kind belong to the category of heavy reconnaissance and / or strike vehicles.
Such a distribution of developments by classes is due to the special capabilities of the aerodynamic design. Often, it is the flying wing that provides the optimal balance of performance and payload required for complex missions. In addition, in some situations, such a scheme is inferior to the normal one in one way or another. Similar schemes, such as tailless, are also actively used.
Individual samples
One of the first unmanned flying wings that reached full-scale operation was the American KillerBee / Bat developed by Swift Engineering and Northrop Grumman. Its first modification had a wing span of approx. 3 m and could carry a load of up to 14 kg. Later, a new version appeared with an increased wing and a load of up to 45 kg. All UAVs of this series are equipped with electric motors and are designed to work with reconnaissance equipment.
The Lockheed Martin RQ-170 Sentinel reconnaissance UAV was widely known at one time, but most of the data about it is still classified. This device has a swept wing with a span of at least 12 m and is equipped with a turbojet engine. According to various sources, it carries a radar station, electronic and optical reconnaissance systems, etc. The possibility of using weapons is mentioned.
In 2011, under unclear circumstances, one RQ-170 landed in Iran. Local experts carefully studied it - and soon the Iranian industry released several new flying wings at once. A full-size "copy" of the American UAV was the product "Shahid-171" or "Simurg". There is also a smaller "Shahid-191" / "Saegeh". However, the theme of flying wings was worked out by Iran even before the American model was received - several lightweight models of this kind are known.
Of great interest is the Northrop Grumman X-47B project, the purpose of which was to create a heavy UAV for work on the deck of an aircraft carrier. The product with a wingspan of 19 m (folds up to 9.4 m) had a maximum take-off weight of more than 20 tons. The turbojet engine provided a high subsonic speed. The wing provided for two compartments for equipment or weapons with a carrying capacity of 2 tons. The X-47B could carry out reconnaissance and use weapons or refuel other aircraft.
There are projects of unmanned flying wings in Europe. So, in 2012, the first flight of the nEUROn UAV, developed by several countries under the general leadership of the French company Dassault Aviation, took place. With a span of 12.5 m, such a device has a maximum take-off weight of 7 tons and must carry up to 450-470 kg of weapons or special equipment.
The direct competitor of this UAV is the Taranis product from the British BAE Systems. A turbojet subsonic UAV with a wingspan of 10 m can carry a variety of equipment and weapons required for a specific mission.
It should be noted that this is by no means all the “flying wing” UAVs created in recent decades. Within the framework of the current "boom" of drones, since the beginning of this century in different countries, similar devices of different classes have been created and tested, created for experiments or for operation in the military. It is obvious that in the future the number of such projects will constantly grow.
Inconspicuous wing
The flying wing has a number of advantages, and one of the main ones is the possibility of reducing the aircraft's signature for the radar. This is actively used in modern projects - and almost all new types of flying wings turn out to be "stealth".
Lockheed Martin appears to be the most successful in this area. Its RQ-170 UAV is known as one of the most secretive in its class. According to various sources, this is ensured both by the special shape of the airframe, which provides re-reflection of radio signals, and by construction materials that attenuate the reflected radiation. However, the design features are not officially disclosed - as well as the characteristics.
In July 2016, as part of the flight tests of the Dassault nEUROn UAV, it performed several flights over the aircraft carrier Charles de Gaulle and escort ships. During these events, the drone's ability to detect large surface objects and the ability of ships to detect an inconspicuous vehicle were studied. In addition, the interaction between the fleet and the UAV was worked out. Unfortunately, the most interesting details from a technical point of view were not reported, but the purpose of such exercises could well have been to work out issues of visibility.
Using volumes
The "flying wing" differs from other aerodynamic schemes by the increased internal volumes available for the placement of the units. Specific contours impose some limitations, but the right approach will get all the benefits you want.
Most often, in foreign practice, the available layout space is used to accommodate fuel tanks, which makes it possible to increase the flight range. In addition, due to the use of appropriate equipment, the UAV can become an air tanker. The principled possibility of this has already been confirmed by the experienced X-47B.
Almost all heavy UAVs also have internal bays for weapons or other payloads. The possibility of their organization is also related to the available volumes inside the wing. However, almost all attack drones can carry only a few weapons - due to the limited size of the airframe and, accordingly, the cargo bay.
The space inside the RQ-170 is used in an interesting way. According to some reports, the antennas of its radar and RTR are located inside the leading edge and in other parts of the wing. Thus, not only the volume, but also the area is effectively used.
Flight characteristics
The specific aerodynamics of a flying wing imposes certain restrictions. So, such a UAV does not differ in course stability and may experience problems with pitch control. In modern projects, such problems are solved with the help of sophisticated controls that receive information from various sensors and quickly respond to emerging situations.
The "flying wing" scheme shows itself well only at subsonic speeds. Because of this, modern UAVs of this kind have restrictions on flight speed, and within very wide limits. So, the average Northrop Grumman Bat accelerates to only 166 km / h, and the heavy Dassault nEUROn is capable of 980 km / h. At the same time, larger vehicles are able to stay in the air for hours and show a range of more than 2-2.5 thousand km.
However, in the field of UAVs with an increased range and duration of flight, foreign flying wings do not yet compete with a normal scheme adapted for such tasks. The swept wing of a large relative thickness in terms of carrying capacity loses to a thin straight wing with a large aspect ratio.
For some tasks
As you can see, foreign UAV developers have long noticed all the advantages of the "flying wing" scheme and are using it in the most active way. However, this version of the aerodynamic appearance is used only in individual cases when it is justified. In other situations, other schemes turn out to be more useful or convenient from the technological point of view, incl. normal.
Currently, a number of unmanned aerial vehicles of a number of classes and for various purposes are at various stages of development, testing and operation. Some of the promising developments will go into operation in the future and will solve real problems. In the distant future, it is likely that UAVs will be able to partially replace the current manned aircraft. And it is quite possible that among them there will be flying wings.
