Su-35 MULTIROLE FIGHTER

This article is from Russian 'National Defence' English-speaking journal. The author is a well known military and air-space technology journalist and the Editor-on-Chief of the 'Take-off' magazine.








The OCR text.

Andrey FOMIN

 On the world fighter market Russia's Sukhoi is pinning its hopes, in the near future, on the substantially modernized Su-35 multirole fighter. The model must be an interim type between today's Su-30MK in various configurations and a prospective fifth-generation fighter, the deliveries of which may start in the second half of the next decade. The Su-35 is a generation 4++ aircraft employing technologies of the fifth generation. They make it superior to all other fourth-genera­tion fighters currently under devel­opment worldwide. In 2009-2015, owing to these technologies, the Su-35 will dominate the world mar­ket, outperforming other proposed multirole fighters.

The first experimental Su-35, assembled at the Komsomolsk-on-Amur Aviation Production Association (KnAAPO) in summer 2007, made its debut at MAKS-2007 Airshow in Moscow.

The Su-35 has long been a brand name in the aviation world. Since 1992, an export version of the Su-27 fighter (created under the order of the Russian Air Force) has been demonstrated at international air

shows. At the turn of the millenni­um, Su-35 fighters participated in the tenders of Korean and Brazilian air forces. By the mid-decade of the new century, a general concept emerged of a considerably modified Su-27 fighter, which retained the name of Su-35.

What novelties will appear in the Su-35? First, the fighter will get an improved airframe, which will dramatically increase its service life to 6,000 h, 30 years of operation (the time before the first test and recon­dition and the between-repairs peri­od has been increased to 1,500 h, or 10 years of operation). Aerodynamically it is similar to the Su-27. But unlike the Su-30MKI it will feature no canard fins. All the three channels will have electrically signaled control without mechanical cabling. The application of a new integrated control system (devel­oped by the Moscow-based Avionika Research and Production Complex) simultaneously perform­ing functions of several systems -remote control, automatic control, limiting signals system, air signals system, chassis wheels braking sys­tem - will enhance the fighter's handling capability and maneuver­ability.

Among the Su-35 design fea­tures, worth of note is the absence of an overhead brake flap, a standard characteristic of the Su-27. Its func­tions are performed by an active rudder. The Su-35 chassis has been reinforced due to the increased take­off and landing weight of the air­craft. For the same reason, the front bearing has two wheels. Application of radar signature reduction tech­nologies decreases the reflectance of the Su-35 in the X radio waveband and in an angle range of ±60°.

Another essential distinction of the Su-35 from its predecessors of the Su-27 family is the installation of new engines with an increased thrust. Those engines known as 117S have been developed by the Rybinsk-based Saturn Research and Production Association.

Structurally, the engines are a heavily upgraded version of the in-service AL-31F incorporating fifth-generation technologies. They use a new fan, new high and low pressure turbines, and a new digital control system. Provision is made for using a vectored thrust nozzle. The mod­ernization has increased the engine special mode thrust by 16 percent up to 14,500 kgf and in the maxi­mum burner-free mode it reaches 8,800 kgf. Compared to today's AL-31F engines, their capabilities will grow substantially, by 2 to 2.7 times. For instance, TBO will increase from 500 to 1,000 h (first overhaul period is 1,500 h), while the assigned life will rise from 1,500 and 4,000 h.

The 117S engines series produc­tion will be carried out by the Ufa-based Motor Building Production Association jointly with the Rybinsk-based Saturn Research and Production Association. The first production 1175 engines were deliv­ered to KnAAPO in early 2007 for testing on the first experimental Su-35 aircraft.

The distinctive feature of the Su-35 is the employment of a funda­mentally new suite of onboard instruments. Its core is the informa­tion management system (IMS), which integrates functional, logical, informational and software subsys­tems into a single complex that ensures the interaction between the crew and equipment. The IMS includes two central digital comput­ers, data switching and conversion devices and an indication system built on the «all-glass cockpit» concept.

The core of the Su-35 cockpit instrumentation suite are two full-color multifunction liquid crystal displays of the MFI type, a multi­function panel with a built-in display processor, a wide angle colli-matory display on the windshield and a control and indication panel. MFI multifunction displays with a built-in processor measure 9x12 inches (diagonal 15 inches) and have a resolution of 1,400x1,050 pixels. They are intended for reception, processing and displaying graphic, numeric, alphabetic and symbolic information in multiwindow mode. They also display TV information received from onboard TV sensors with synthesized numeric, alphabet­ic and symbolic information imposed on it. Besides, they produce and send video signals in a digital format to the video record unit. The multifunction«panel with a built-in display processor presents the required information and issues commands by pushing the buttons on the button array at any time in flight. The airborne collimatory dis­play with a built-in processor moni­tors the space beyond the cockpit. The information is processed by control signals. The collimator angle of view is 20x30°. In the new cock­pit, the onboard systems and arma­ment are controlled by buttons and switches on the aircraft control joy­stick and engine control levers as well as by a button array on multi­function displays. Thus, the HOTAS concept has been implemented in this type of aircraft. The Su-35 dis­plays and some other avionics are developed by the Ramenskoye-based Instrument Design Bureau and affiliated companies of the Tekhnokompleks Research and Production Association.

The core of the Su-35 stores man­agement system is the Irbis-E advanced phased array radar con­trol system featuring unique target detection range capabilities. It was developed by the Tikhomirov Instrument-Making Research Institute JSC. Structurally, it is an X-band multirole radar with a pas­sive phased antenna array (PAA) mounted on a two-step hydraulic drive unit (in azimuth and roll). The antenna device scans by an electron­ically controlled beam in azimuth and angle of elevation in sectors not less than 60°. In addition, the two-step electrohydraulic drive unit mechanically turns the antenna by 60° in azimuth and 120° in roll.

Thus, owing to the electronic control and mechanical additional turn of the antenna, the maximum angle of beam deflection reaches 120°.

The Irbis-E radar control system detects and tracks up to 30 air tar­gets and engages simultaneously up to eight targets, while maintaining continuous surveillance of the air­space. The system also detects, selects and tracks up to four ground targets in several map-making modes with various resolution at a range of up to 400 km while keeping airspace control.

The Irbis-E radar detects air tar­gets with an absolute cross section of 3 m² on a head-on course at a range of up to 400 km.

Being an improvement on radars with a PAA, the Irbis has much bet­ter capabilities: expanded (by more than twice) operating frequency band, increased from 70 to 120° tar­get detection and tracking zone in azimuth, substantially (by 2-2.5 times) increased effective range, improved antijamming capability, etc. In this aspect, the Irbis is compa­rable to the best foreign counter­parts, outperforming most of the US- and European-made radars with passive and active PAA.

The Research Institute has been developing the Irbis since 2004. By now, the engineering prototypes of the system have passed the required bench trials. The first of them has been installed on the Su-30MK2 fly­ing laboratory and is undergoing flight tests. The first flight of the fly­ing laboratory with the Irbis onboard took place in early 2007 at the Gromov Flight Test Institute. During the flight, the laboratory proved the superior performance of the new radar in the air-to-surface operating mode.

Among other new onboard sys­tems of the Su-35 is modern naviga­tion and radio communications equipment, systems maintaining fighters operation in a formation and a highly efficient electronic countermeasures suite. The compo­nent package of the latter and its complementation with specific jam­ming devices can be determined by the customer.

In addition to the armament mix used on the modern Su-30MK, it is planned to integrate new types of air-to-air and air-to-surface guided missiles, including long-range types, into the Su-35. The maximum ord­nance load of the Su-35 is 8,000 kg installed on its 12 hardpoints.

Currently, the first flying proto­type of Su-35 is undergoing ground tests. Its first flight took place on February 19, 2008. Following the first prototype, another two exam­ples of Su-35 are now being assem­bled at KnAAPO (Komsomolsk-on-Amur Aviation Production Association) and will join the test program this year. Series production and deliveries of the Su-35s to cus­tomers are scheduled for 2010. They will continue in parallel with the entrance of a fifth-generation fighter to the market.

National    DEFENSE

16 / 2008

www.nalionaldefense.ru