1. What kind of aircraft is the MiG-31?
2. What are the main structural features of the MiD-31?
3. Why was new D-30F6 engine chosen for the MiG-31?
4. What provides high interceptor efficiency of the MiG-31?
II. Translate the 5th paragraph of the text in a written form.
III. Make up a summary of the text.
UNIT 9
F-22 Raptor
Vocabulary: fighter, stealth technology, airframe, maintenance, pitch axis thrust vectoring, compressor stall, augmented thrust, nozzle, canopy, stabilator.
The Lockheed Martin/Boeing F-22 Raptor is a single seat, twin-engine fifth-generation fighter aircraft that uses stealth technology. It was designed primarily as an air superiority fighter, but has additional capabilities that include ground attack, electronic warfare, and signals intelligence roles. Lockheed Martin Aeronautics is the prime contractor and is responsible for the majority of the airframe, weapon systems and final assembly of the F-22. Program partner Boeing Integrated Defense Systems provides the wings, aft fuselage, avionics integration, and all of the pilot and maintenance training systems.
Lockheed Martin claims that the Raptor's combination of stealth, speed, agility, precision and situational awareness, combined with air-to-air air and air-to-ground combat capabilities, makes it the best overall fighter in the world today.
The F-22 Raptor is a fifth generation fighter that is considered a fourth-generation stealth aircraft. Its dual afterburning Pratt & Whitney F119-PW-100 turbofans incorporate pitch axis thrust vectoring, with a range of ±20 degrees. The maximum thrust is classified, though most sources place it at about 35,000 lbf (156 kN) per engine. Maximum speed, without external weapons, is estimated to be Mach 1.82 in supercruise mode. The absence of variable intake ramps generally limits speeds to approximately Mach 2.0. Such ramps would be used to prevent engine surge resulting in a compressor stall, but the intake itself may be designed to prevent this.
The true top speed of the F-22is unknown to the general public. The ability of the airframe to withstand the stress and heat is a further key factor, especially in an aircraft using as many composites as the F-22. However, while some aircraft are faster on paper, the internal carriage of its standard combat load allows the aircraft to reach comparatively higher performance with a heavy load over other modern aircraft due to its lack of drag from external stores. It is one of only a handful of aircraft that can sustain supersonic flight without the use of afterburner augmented thrust (and its associated high fuel consumption). This ability is now termed supercruise. This allows the aircraft to hit time-critical, fleeting or mobile targets that a subsonic aircraft would not have the speed to reach and an afterburner dependent aircraft would not have the fuel to reach.
The F-22is highly maneuverable, at both supersonic and subsonic speeds. It is extremely departure-resistant, enabling it to remain controllable at extreme pilot inputs. The Raptor's thrust vectoring nozzles allow the aircraft to turn tightly, and perform extremely high alpha (angle of attack) maneuvers such as the Herbst maneuver,Pugachev's Cobra, and the Kulbit. The F-22 isalso capable of maintaining a constant angle of attack of over 60°, yet still having some control of roll.
The F-22cockpit is a glass cockpit design without any traditional analog flight instruments and represents a marked improvement on the cockpit design of previous advanced aircraft. The leading features of the F-22cockpit include simple and rapid start-up, highly developed HMI, light helmet, large anthropometric accommodation and highly integrated warning system. Other main features include large single-piece canopy, side stick and improved life support systems.
All internal displays are designed to be used with night vision goggles because the aircraft lacks optical or IR vision devices.
The YF-22A prototype and production F-22A are sometimes confused in pictures, often at angles where is difficult to see certain features. Several small design changes were made from the YF-22 to the F-22A. Swept-back angle on the wing's leading edge was decreased from 48 degrees to 42 degrees, while the vertical stabilizer area was decreased 20%. To improve pilot visibility, the canopy was moved forward 7 inches (178 mm) and the engine intakes were moved rearward 14 inches (356 mm). The shape of the wing and stabilator trailing edges was refined to improve aerodynamics, strength, and stealth characteristics. Also, the vertical stabilizer was shifted rearward. The airframe also features three internal weapons bays on the bottom and sides of the fuselage.
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