Kh-55 strategic cruise missile (KV-500)

X-55 is made by the normal aerodynamic scheme with a straight wing of relatively large elongation. (see projections on the side, top, bottom) The plumage is entirely rotatable. In the transport position the wing and nacelle are retracted into the fuselage, and the plumage is folded (see the layout diagram).

Two-circuit single-shaft turbojet engine P-95-300 (see photo) with a circular combustion chamber, designed under the guidance of Chief Designer O.N.Favorsky, is located on a retractable subfuselage pylon. The low pressure compressor is a two-stage fan, the high pressure compressor is a seven-stage axial compressor. The oil system is autonomous. R95-300 develops a static take-off thrust of 300 ... 350 kgf, having a transverse size of 315 mm and a length of 850 mm. With its own weight of 95 kg, the R-95-300 has a weight return of 3.68 kgf/kg - at the TRD level of modern combat aircraft. The R-95-300 axial compressor, with a dual circuit level of 2, provided a compression level of 8.5. Specific air consumption is only 0.785 kg/kgf x h - much less than the similar parameter of TRD and DTRD of combat aircraft (for R-95Sh - 0.86 kg/kgf x h, for NK-22 - 0.96 kg/kgf x h). R-95-300 was created taking into account a fairly wide flight range inherent in cruise missiles, with the ability to maneuver in height and speed. The engine is launched by a pyrostarter placed in the tail coca of the rotor. In flight, when the nacelle is released, the fuselage tail coca is extended to reduce resistance (the coca is extended by a spring held in tension by a nichrome wire, which is burned by an electric impulse). To perform the flight program and regulation, P-95-300 is equipped with a modern automatic electronic-hydromechanical control system and a built-in 4 kW electric generator. In addition to the usual types of fuel (aviation kerosene T-1, TC-1 and others), a special synthetic combat fuel T-10 - decylin - was developed for R-95-300. T-10 is a high-calorie and toxic compound, and it was with this fuel that maximum missile performance was achieved. The peculiarity of T-10 is its high fluidity, which requires particularly careful sealing and sealing of the entire missile fuel system.

As the missile's range flight lasted several hours, conventional battery-powered power sources did not provide such a long service life for on-board systems. They are powered by the built-in small-size electric generator RDC-300.

The need to place a significant fuel reserve with limited size led to the organization of the entire fuselage of the X-55 in the form of a tank, inside which the wing, combat unit, fittings and a number of other units are placed in airtight openings. Flats of the wing are folded into the fuselage, placed one above the other. When releasing the planes are at different heights relative to the construction horizon of the product, fixing with different angles of installation, so the flight configuration of the X-55 becomes asymmetrical. Foldable and tail fins are made, all surfaces of which are wheeled, and the console hinged twice breaks. The keel was initially folded sideways, but then the consoles were unified, and on the keel there was another additional hinge. To reduce the overall length of the retractable tail coc was made and folded "harmonica". The nichrome wire that pulled it down was burned by an electric impulse and the coc was spread out by a spring.

The engine went down under the action of the pyroelectric pusher, after which the opening leaves of the hatch closed the opening, maintaining the aerodynamic purity of the product. The pyrotechnic pushers also opened the wing and plumage consoles, and these mechanisms worked at high pressures up to 350 atm., literally throwing the units out, where they were held by locks.

With regard to the assembly of the rocket, great effort required its manufacturability, which is necessary for mass production. The rocket, assembled from separate aggregates, had to have proper durability, rigidity and alignment of docking compartments, providing the required cleanliness and accuracy of bypasses - under the conditions the last one at X-55 was measured in fractions of millimeter.  It was necessary to establish production of separate interchangeable compartments, assembled in parallel and going to the general assembly of the fuselage, which was reduced to welding the ring seams of "cigar". The fully welded design, which replaced the usual heavy-duty flange joint arrangements on bolts and studs, provided much greater weight perfection, but also required a specific assembly technique. The compartments were placed in the general assembly slipway, which set a clear correspondence of aggregates, were adjusted and docked on frames-belts, welded on the spot, and then all the "cigar" assembly was taken out of the slipway and boiled finally.

The peculiarity of X-55, caused by its extremely light and "delicate" construction, was the solution of suspension under the carrier. Usually rockets, including the heaviest ones, cost one bugel attached to a powerful bendshaft (so hung 12-ton X-20). For the openwork power scheme X-55 used the organization of the suspension with four spaced units, evenly distributing the forces on the structure. When assembling them had to be cut on a special machining center at the same time, as well as the attachment units of planes, achieving unambiguous compliance with the installation dimensions.

The X-55 fuselage power pack is formed by bends-frames, which carry the units, equipment and provide docking of the body compartments. Lightweight design, frames have made complex shapes, with very high thin-walled ribs and walls. Providing the given contours with numerous transitions on the thickness of edges and walls, the frames were made by precise stamping with the subsequent complex milling and boring on CNC machines and machining centers of the mechanical shop. The main and most difficult problem was welding of large structural parts. The fuselage was fully welded from AMG-6 alloy.

In addition to the proper strength, rigidity and accuracy of the contours, the tank compartment, which made up the entire fuselage, had to provide tightness, and the trouble added high fluidity of special fuel, capable of seepage everywhere. The task was complicated not only by the large number of welds, but also by their presence inside the compartments in hard-to-reach places. For example, the electric harnesses of the control valves were laid inside a flat tube welded into the structure that passed through the entire tank. Panels and assemblies made of AMG-6 were boiled by argon-arc welding on special welding machines, but some of the units in the compartments had to be boiled manually.

The finished product and all its seams were thoroughly checked for tightness. However, if external leaks were detected and eliminated quite simply, the internal tightness diagnostics was a problem. And such leaks were no less unpleasant - due to the fact that the engine, control units and BC were placed in the tank compartment, fuel leakage could disable the "filling" of the rocket. Possible defects of welding were checked by X-ray control, leaks and pores were detected by acetone, "clean" control for tightness was carried out by special liquid leak detectors based on helium, which has ultra-high fluidity and penetrating properties. At the slightest non-provrovar, "fistulas" and low thickness of the sheet, helium seeped even through the structure of the material and the crystal lattice of the metal.

An unpleasant side effect of welding was the warping of the structure due to residual internal stresses during heating. The fuselage elements were thermo-calibrated to remove deformations while observing the specified contours. To avoid a "leash", the welded components were placed in thick-walled steel sleeves with electric heating, where they were released.

Measures to reduce radar and thermal signature have been implemented in the missile design. Due to the small middlet and clean bypasses, the missile has a minimum EPR, which makes it difficult to detect by air defense. The surface of the hull has no contrast slits and sharp edges, the engine is covered by the fuselage, widely used structural and radio absorbent materials. The lining of the fuselage nose, wing and plumage is made of special radio absorbent materials based on silicon composite.

 The missile guidance system is one of the essential differences between this cruise missile and previous aircraft weapons systems.  The missile uses an inertial guidance system with location correction on the terrain. A digital terrain map is entered into the onboard computer before launch. The control system provides long autonomous flight of X-55 regardless of the length, weather conditions, etc. Usual autopilot on Kh-55 was replaced by electronic onboard control system BSU-55, which worked out a given flight program with the stabilization of the missile on three axes, holding the high-speed and high-altitude mode and the ability to perform given maneuvers to evade interception. The main mode was the route passage at extremely low altitudes (50-100m) with the relief envelope, at a speed of the order of M=0.5-0.7, corresponding to the most economical mode.

X-55 is equipped with a newly developed compact thermonuclear BC with a 200Kt charge. At a given accuracy (CWO no more than 100m), the charge power provided the defeat of the main targets - strategic centers of state and military administration, military industrial facilities, nuclear weapons bases, missile launchers, including protected objects and shelters.

Carriers of the missile are long-range bombers TU-95MS and Tu-160. Each Tu-95MS-6 bomber can carry up to six missiles, located on the drum launcher MKU-6-5 catapult type in the cargo compartment of the aircraft (see photo). Variant Tu-95MS-16 has sixteen X-55: six on MKU-6-5, two on the inner wings of the ejection unit AKU-2 in the fuselage and three - on external units AKU-3, placed between engines. In two gruzootseke supersonic Tu-160 can accommodate 12 long-range cruise missiles X-55SM (with additional tanks) or 24 conventional cruise missiles X-55.

Modifications to the rocket:

X-55OC (product 121) differs guidance system with an optical correlator on the reference image of the area.

Modification of X-55SM (product 125) is designed to hit targets at a distance of up to 3500 km. The guidance system remained the same, but a significant increase in range required almost one and a half times the fuel reserve. In order not to change the used design on the sides of the fuselage equipped with conformal tanks for 260 kg of fuel, almost did not affect the aerodynamics and balancing of the rocket. This design allowed to save the size and possibility of placing six missiles on the ICU inside the fuselage. However, the weight increased to 1465 kg forced to limit the number of missiles on the underwings TU-95MS (can hang eight X-55SM instead of ten X-55).

The non-nuclear version of the X-55 received the designation X-555 (see photo). The new missile is equipped with an inertial-Doppler guidance system that combines topography correction with optoelectronic correlator and satellite navigation. As a result, the CWO was about 20 m. The new missile is equipped with an inertial Doppler guidance system that combines terrain correction with an optoelectronic correlator and satellite navigation. The X-555 can be equipped with several types of BC: blast, penetrating - to hit protected targets or cassette with shrapnel, blast or cumulative elements to hit the area and long targets. Due to the increase in the mass of BC, the fuel reserve and, accordingly, the flight range was reduced to 2000 km. Eventually, the more massive BC and new control equipment increased the starting mass of X-555 to 1280 kg. The X-555 is equipped with conformal suspended tanks for 220 kg of fuel.

The X-65 is a tactical anti-ship modification of the X-555 with a conventional warhead.