Wednesday, 29 April 2015

Tupolev Tu-160 Blackjack

Tupolev “Heaviest bomber” – Blackjack

The Tupolev Tu-160 Blackjack is heaviest and most powerful combat bomber aircraft of all time. This strategic bomber was built to a programme which began in 1967 when DA (long- range aviation) Gen-Col Reshetnikov studied the Sukhoi T-4MS (so-called ‘200’) and Myasishchev M- 20. VVS chief Kutakhov assigned Sukhoi smaller aircraft, but the excel­lence of the M-20 led to its adoption, after modification as the M-18, with a horizontal tail instead of a canard. With so big a project CAHI’s top men, Byushgens and Svishchyev, led the aerodynamic backing. It was finally decided only Tupolev was big enough to tackle the job.
In January 1975 design went ahead at Tupolev as Aeroplane K, with the out-of-sequence Izdelye number 70. The Service designation, Tupolev Tu-160, is what might have been expected as the OKB number. Though Col Evgeni Vlasov called the Tu-160 ‘an expensive countermeasure to the B-l’, in fact it would probably have gone ahead even if the USAF bomber had never existed.
Authorisation to create this bomber specified an optimised aircraft regard­less of cost, and the Kremlin demand continued after cancellation of B-l on 30 June 1977. Indeed it was exactly at this time that the OKB received an order for prototypes. Dr Alexei Tupolev, then OKB titular head, appointed as team leader Valentin Bliznyuk. Prototype assembly was to be in the Tupolev facility at LII Zhukovskii, with any subsequent series production to be at Kazan.
According to Vlasov, looked at from the outside, the Tupolev Tu-160 Blackjack and B-1B are similar. This is explained by the fact both aircraft have similar objec­tives: a long radius of action despite a heavy load of equipment and stores, the capability of deceiving enemy defence systems at low or high alti­tudes, and of having minimum radar, IR, optical and acoustic signatures. However, they bear resemblance from the outside only; the differences are fundamental’.
Perhaps the most basic single differ­ence is that the Tupolev Tu-160 Blackjack has 80% more installed engine power. Last of the engines to bear the initials of KB director Nikolai Kuznetsov, the NK-32 is one of the most powerful military engines in history, with a take-off rating of 14,000kg (30,843lb) and maximum augmented thrust of 23,100kg (50,926lb). A second differ­ence is that, though significantly larger than the USAF bomber, the Tu-160 has smaller radar cross-sections and lower aerodynamic drag.
Col-Gen Boris Korolkov com­mented that there is a marked differ­ence between the radar cross-sections, even ignoring the B-1B’s external carriage of missiles and the claimed much better performance of the Tupolev Tu-160 Blackjack’s EW (electronic-warfare) systems, though in fairness to the US aircraft it has got better. Finally, partly thanks to idealised variable- geometry inlets, the Tu-160 is faster at sea level and almost twice as fast at alti­tude.
The four engines are installed in paired nacelles under the enormous fixed inner wing. This has a lead­ing edge which in plan view curves continuously from a sweep angle of 90 deg where it blends imperceptibly into the fuselage near the cockpit. Thanks to this acute sweep, the leading-edge radius is large, affording both space and good antenna sizes for powerful internal ECM (electronic counter- measures). Two giant beams link the pivots for the outer wings, 19.2m (63ft) apart, with the sweep angle selected by control-stick buttons offering 20 deg, 35 deg or 65 deg.
Each outer wing is straight-tapered from root to tip, with full-span four- section hydraulically driven slotted leading-edge flaps (essentially slats) and full-span four-section double- slotted trailing-edge flaps. Outboard of the trailing-edge flaps, but stopping 3.5m (11ft 6in) short of the wingtip, are powered ailerons. These are all- speed primary roll-control surfaces, but backed by spoilers and tailerons. With flaps extended, they droop 20 deg. After prolonged research the decision was taken to retain the optimum engine installation, leaving nowhere for the wing trailing edge to penetrate at 65 deg sweep. The prob­lem was solved by making the inboard trailing edge hinge progressively upwards to form a large vertical fence at maximum sweep.
The tail looks deceptively conven­tional. The fixed fin is actually very sharply swept, with large chord but little height. On it are mounted the swept and sharply tapered slab tailplanes and the one-piece unswept but sharply tapered rudder (there is no fin above the tailplanes). The tail- planes are more strictly tailerons, because they can operate together for pitch authority or in opposition for control in roll. Their span is 13.25m (43ft 5in) and area 55.6sq m (598.5sq ft); leading-edge sweep is 44 deg and they are without dihedral or anhedral. All flight-control surfaces are driven by electro-hydraulic power units with dual FBW (fly by wire) and standby mechanical signalling.
The fuselage cross-section is the minimum necessary for crew, fuel and payload, and is significantly less than that of the B-1B or Tupolev Tu-22M. Drag and radar cross-section are further reduced by the acute angle of the con­ical nose, and by the use of special computer routines to achieve optimum shape and control machine tools in production. Of over forty-five an­tennas, only three project as blades or spikes. Apart from the previously mentioned hinged ‘flap fence’, no fences or vortex generators were needed anywhere.
Structurally, Tupolev Tu-160 Blackjack broke new ground with Tupolev in its very extensive use of honeycomb sandwich skin and precision-controlled RAM (radar-absorbent material) covering. Each engine-pair is installed in a rec­tangular-section nacelle hung under the inboard wing, with nacelle width increasing progressively from front to rear and the rear upper portions pro­jecting above the wing as separate jet- pipe fairings. Despite experience of horizontal-wedge inlets with the Tupolev Tu-144 and Tupolev Tu-22M-3, for minimum radar cross-section the inlets were designed similar to those of the B-1A (not the fixed-geometry B-1B) with a vertical splitter leading back to an inner wall variable in profile and throat area. ANTK Tupolev believe this inlet achieves higher pressure recovery and lower drag from 0 to Mach 1.9 than any other inlet flying. The outer wall is also vertical, incorporating five inward suction-relief doors of progressively reduced height, matching the profile of the duct which at the throat is tall and narrow. For ‘stealth’ reasons, con­sideration is being given to modifying these doors with zigzag edges. As in Tupolev’s previous supersonic bom­bers, the complete variable nozzle of each engine projects behind the nacelle, the engine being withdrawn on rails to the rear.
To minimize radar cross-section of Tupolev Tu-160 Blackjack, the nose landing gear is installed behind, not under, the pressurised crew compartment. It carries landing and taxi lights, and spray/slush deflec­tors are mounted behind the twin wheels. Tyre size is 1,080mm by 400mm, the truck being hydraulically steerable through ±55 deg and retracted pneumo-hydraulically to the rear into a bay with left/right doors which remain open when the gear is extended. Each main landing gear has a six-wheel bogie, the tyre size being 1,260mm by 425mm. Unlike the Tupolev Tu-22M, all three pairs of wheels are in line, because this aircraft operates from uncontaminated paved runways. The bogie supports a massive oleo leg made by Hydromash, installed inboard of the engine nacelle, which restricts the track to 5.4m (17ft 8in). Wheel- base is 17.875m (58ft 7in). The main drag strut incorporates the retraction jack which pushes the gear to the rear. The leg pivots back and the lower por­tions also move inwards, while the bogie somersaults to lie inverted in a box which projects upwards to cause ‘canoe’ blisters between the engines and the fuselage. These blisters taper at the rear into shallow pipe/cable- loom fairings carried externally on each side of the rear-fuselage integral tanks to the closure bulkhead at the aft end.
A very large braking parachute of Tupolev Tu-160 Blackjack can be streamed from the fairing between the horizontal and vertical tails. Inter­nal fuel capacity is 50 per cent greater than that of the B-1B. Tankage is integral throughout, the main refuelling doors being in the front face of the inboard leading edge. Each aircraft was built with provision for a retractable inflight-refuelling probe above the nose, but in confor­mity with START treaties this capa­bility remains unused. There are four autonomous hydraulic systems, each energised by an engine-driven pump to the high pressure of 280kg/sq cm (3,983lb/sq in).
Dimensions and data of Tupolev Tu-160 Blackjack:
  • Wingspan (20 deg) 55.7m (182ft 9in), (35 dcg) 50.7m (166ft 4in), (65 deg) 35,6m (116ft 9in)
  • Length 54.1m (177ft 6in)
  • Wing area 340sq m (3,660sq ft)
  • Empty weight 18,000kg (259,000lb)
  • Maxi­mum fuel 171,000kg (376,984lb)
  • Loaded weight 275,000kg (606,260lb)
  • Maximum landing weight 165,000kg (363,762lb)
  • 2 internal bays for 40,000 kg (88,185 lb)
  • 2 internal rotary launchers each holding 6 × Raduga Kh-55 cruise missiles )
  • 12× Raduga Kh-15 short-range nuclear missiles

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