B-2 SPIRIT

In June 1977, US President Jimmy Carter decided to suspend the construction program of the new B-1A strategic bomber. This meant that the B-52, with almost twenty years of service behind it, would remain the basic type of American aircraft for many years to come. Meanwhile, the USAF decided to start work on a new bomber based on completely new technologies (ATB - Advanced Technology Bomber). Its main advantage in the confrontation with the Soviet anti-aircraft defense system was to be the feature of "invisibility" or, in other words, low observability of the aircraft for radar devices. The first work on the ATB bomber was carried out in 1978. The main contractor for the ATB project was the Northrop / Boeing team, in which Northrop played a leading role, while Boeing became the main cooperator. The design of the ATB aircraft was based on the strict requirements for long range, high armament load and, of course, low level of observability. Like any of the stealth aircraft construction programs, the ATB program was top secret. From unconfirmed sources it appears that the piloted B-2 model took off for the first flight in mid-1989. The fact is, however, that this structure in the 1: 1 scale was built using only model tests (without building a mock-up of the aircraft) and with a very wide the use of computer aided design. The B-2 plane was designed with unprecedented accuracy of reproducing its geometry. One of the most difficult problems that was solved was the creation of a three-dimensional database for mapping the body of the aircraft. However, this problem was resolved and the B-2 is the world's first aircraft of this size and complexity to be built without the need to build a dummy. During the development of the aircraft, almost 900 new materials and technological processes were patented. In summary, the work on the B-2 became an impulse for the development of new design and construction techniques. Originally, the USAF expressed an interest in purchasing 132 copies, of which 120 were designed to carry nuclear weapons. However, the rapidly changing political and economic situation in the world (the collapse of the USSR) resulted in the reduction of orders to 21 units. The B-2 is a two or three seater (depending on the difficulty of the planned missions) strategic bomber, built in a flying wing configuration. The plane forms a wing with no fins understood in the classical sense. The airframe consists of practically four main parts: a center wing, two attachable wings (caisson structure) and a center wing segment being its stern part. The center wing, resembling a trapezoidal box, houses the weapons compartments, four engine nacelles, landing gear compartments, equipment and a crew cabin for three people. In the upper part there are air inlets, shifted back to the leading edge. The airfoil is equipped with multi-part moving surfaces located on the zigzag trailing edge and acts as controls (height and direction), ailerons and flaps. The two surfaces attached to the wing consoles are divided horizontally into two segments (upper and lower) each. They spread out to play the role of the rudder (with asymmetrical spreading of both consoles) or of air brakes (with symmetrical spreading). The movable control surfaces take up about 15% of the total lift area of the aircraft (69.675 m2, for comparison the maximum lifting area of the Su-22M4 aircraft is 38.49 m2). The basic construction materials of the airframe are composites, mainly - epoxy-carbon and epoxy-aramid (kevlar). Honeycomb structures have been widely used for the covering and internal components of the structure. The surface of the plane was covered with a special varnish that disperses radar radiation. Three-support chassis with front support point; main - bogie, pulled up towards the plane of symmetry of the plane, front - two-wheeled, pulled to the rear. The aircraft is propelled by four General Electric F118-GE-110 two-flow jet engines without afterburners with a thrust of 4 x 84.50 kN. They are located inside the lobe, in its upper part. The exhaust nozzles are located above a relatively large surface, and the exhaust gases are cooled by a stream of cold air, which allows to reduce the thermal signal and noise of the drive units. It is possible to install a special device for mixing exhaust gases with fluorosulfuric acid in order to prevent the formation of visible condensation streaks when flying at high altitude. The plane is equipped with a digital control system with a four-time reservation. In addition to the basic tasks performed by classic control systems, it effectively reduces operational overload (by changing the load distribution) and gusts, improving flight comfort and safety at low altitude. This system is most likely adapted to automatic flight stabilization in the event of engine failure (thrust asymmetry) or other types of damage, e.g. mechanical airframe (overshoot, etc.). Western sources say that the B-2 has a maneuverability not inferior to that of fighter planes. Stealth properties were achieved by adopting a flying wing system, curvilinear shapes, the use of RAM (electromagnetic energy absorbing) materials and appropriate structures that absorb or scatter radar radiation. The outline of the plane in the top view consists of twelve straight lines directed in strictly defined directions. The curvilinear contour of the airframe, from the canopy to the air inlets, is shaped by the same set of rules. RAM materials were used for the leading edges of the airfoil and the wing tips, and in the brackets inside each inlet. Probably most of the plane's surface is covered with honeycomb structures that absorb (scatter) radar waves and a varnish containing heavy absorbents. Additionally, the B-2 is made almost entirely of composite materials. Due to the applied solutions, the radar station with typical wavelengths detects the plane flying towards the station from a distance of approx. 20 km. For comparison, the same station, with the same assumptions, detects the F-117A from a distance of 10 km, the B-1B from 30 km, and the B-52 from 95 km. Many aviation specialists call the B-2 a stealth plane of the second generation, while the designers of the plane emphasize that the Spirit is not only an "ordinary" stealth plane, but above all a "completely new technology plane". Technical data: Maximum speed: 1040 km / h, maximum ceiling 15100 m, maximum range: 9700 km.