The Su-27UBK ("K" for "Kommercial"), the Su-27UB export version with modified on-board equipment, is in service with the Air Forces in China, Vietnam, Ethiopia. The power plant of the Su-27UB(K) aircraft consists of two AL-31F by-pass afterburning turbojet engines. The peculiarity of the AL-31F is the turbine blade structure that features unique mechanical and operating characteristics. The engines can be operated in a wide range of altitudes and flight speeds. The variable air intakes are with a variable wedge and blow-in door on the lower surface. A special inlet screen is provided to protect the engines against foreign objects during take-off and landing.
The Su-27UBK avionics comprises four interconnected systems: Armament Control, Integrated Flight and Navigation, Communication and On-board Defence Systems. All systems are interconnected. The Armament Control System enables the long-range missile engagement against a single target and a group target, and close-in combat manoeuvres with the use of missiles and a gun. The Integrated Flight and Navigation System controls the flight when guiding, as well as ground target approaching, en-route flight, return to the airfield and the inter-aircraft navigation. A unified communication system comprising the VHF and HF radio sets was installed on the aircraft for the first time in Russia.
The missiles are located in the aircraft missile launchers and catapult launchers on ten stores: 4 under the outer wings, 2 - under the wing tips, 2- under the engine nacelles and 2 - under the center wing section between the engine nacelles ("tandem" layout). The aircraft carries up to 6 R-27R1 or R-27ER1 medium-range semi-active radar-guided missiles, the R-27T1 or R-27ET1 IR homing missiles. The R-73E short-range IR-homing missiles can be mounted on four underwing stores for a close air combat. The Su-27UBK is equipped with a built-in GSh-301one-barrel 30-mm rapid-firing cannon (in the right-side leading-edge wing extension) with an ammunition load of 150 rounds. To hit ground targets, up to eight unguided 500 kg or sixteen 250 kg air bombs or up to six NAR S-13 and S-8 rockets (30 122-mm or 120 80-mm rockets, respectively) can be mounted on the aircraft. Various combinations of missiles and rockets are possible.
The Su-27UBM is an upgrade to standard Su-27UB trainers, adding a new mission computer, an extra channel to the weapons control system, a new AMLCD cockpit display, and upgrades to the N-001 radar [the same features added in the proposed Su-30KN upgrade]. The SU-27UBM was developed on the incentive and with the finance of the JSC "Irkutsk Aviation Industrial Association" (IAIA).
The modernization philosophy was proposed by the Air Force High Command and made provisions for incremental buildup of aviation complexes capacity. A cooperation venture centered around the common project was established for the purposes of its implementation. Beside IAIA and Research and Development organizations of the Air Force, the Sukhoi Experimental Design Bureau, the Aerospace Equipment Corporation, a number of other Design Bureaus and manufacturers were brought together. Both the developers and the representatives of the Air Force emphasize that the adopted program is optimal by its "efficiency-cost-feasibility" parameters.
In the course of development of SU-27UBM, technical solutions applied for the upgrade of the SU-30 fighters to the SU-30KN version were employed, those that afforded to convert air superiority fighter into a truly multi-functional fighter capable of successfully attacking ground targets with high-precision weapons.
On March 6, 2001, upgraded aircraft SU-27UBM, hull No.20 and SU-30KN, hull No.302 that have already passed the flight testing stage including armament application sorties, were presented to the Command of the Ministry of Defense of Russian Federation at the Flight Research Institute after M.M.Gromov airfield in Zhukovsky. The SU-27UBM demonstrated to the Command of the Ministry of Defense of Russian Federation was the first upgraded combatant aircraft. Its conversion from production SU-27UB took mere four weeks. For all that, about fifty new instruments and devices were installed on the aircraft that caused the weight of onboard avionics equipment to increase by only 30 kg.
A multi-functional computational complex (MCC) was built into the structure of onboard equipment that assumed processing of a number of new functions. Therein are integration of information from an array of sensors and control of new types of weapons introduced into the SU-27UBM armament suite. Consequently, the onboard radar RLS N001 attained capacity of functioning in air-to-surface mode, affording the aircraft to attack ground and water targets irrespectively of weather conditions and time of day. A receiver of a satellite navigation system was introduced into the structure of the navigation complex.
At the initial stage of modernization, the weapons suite of the SU-27UBM was supplemented by RVV-AE air-to-air missiles, as well as broad range of air-to-surface ordnance including Kh-31A, Kh-31P, Kh-29T missiles, glide bombs, etc.
By the results of testing, proposed upgrade version of SU-27UB and SU-30 aircraft was adopted as fundamental by the Air Force of Russian Federation. Russian Air Force plan to implement modernization of 30 SU-30 and SU-27UB during the years 2002 through 2004. In the meantime, the work of upgrading the SU-30 and SU-27UB fighters performed at the IAIA incentive suggests further increase of combat capacities of those wonderful aircraft.
At the International Aerospace Trade Show MAKS-2001, a life-size operational dummy cockpit featuring the concept of information and control environment was first presented by the JSC IAIA in summer 2001. This is the project for the second stage of upgrade of the SU-27UBM and SU-30KN aircraft.
In the course of the second stage of upgrade, increase of combat efficiency is intended to be provided by equipping the cockpit with advanced information and control environment comprised of several multi-functional indicators with LC displays and 5"x5" and 6"x6" matrices that would replace mechanical instruments in the front and rear cockpits of fighter types SU-27UBM and SU-30KN.
Onboard radar would also be upgraded by means of equipping it with phased-array antenna (FAA) with electronic beam scan. That would provide capability for multi-channel control of air-to-air guided missiles for several airborne targets simultaneously, application of ordnance at a targeting prompt of onboard radar and navigational complex data.
Within the framework of the third stage of modernization, it is intended to supplement the armament suites of SU-27UBM and SU-30KN with supersonic anti-ship missile (ASM) "Yakhont" created by the Machinery Building Research and Manufacture Association. That would be a fundamentally new class of combat aviation complex. As compared to the existing specimen of missile weapons (Kh-31A, "Moskit"), its range is extended by two times, from 150 to 300 km.
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