The aircraft comes from a long line of Mikoyan lightweight fighters, such as the MiG-15 and MiG-21. It is about the same size as the MiG-21 (shorter by 1.3m but wider by 4.5m), but noticeably smaller than its immediate predecessor, the MiG-29. Take-off weight is estimated at around 12 tonnes; maximum take-off weight at about 16 tonnes.
In early 2002 Sukhoi was chosen as prime contractor for the planned Russian fifth-generation fighter is called the PAK FA [ Perspektivnyi Aviatsionnyi Kompleks Frontovoi Aviatsyi - Future Air Complex for Tactical Air Forces]. This intermediate class twin-engined fighter will be larger than a MiG-29 and smaller than a Su-27.
The aircraft will feature a long combat radius, supersonic cruise speed, low radar cross section, supermaneuverability, and the ability to make short takeoffs and landings. In accordance with the technical requirements, the PAK FA will have a normal takeoff weight of 20 tons, which is close to the average normal takeoff weight of the two American airplanes, the F-35 JSF (17.2 tons) and the F-22 (24 tons). The new fighter (a medium version) will have a traditional wing form, though the experience gathered as a result of Berkut's test flights will be taken in consideration when designing the fighter. It is supposed that it will be created using the Stealth technology, and equipped with two AL-41F engines by the Saturn scientific and industrial enterprise, a radar system with an active phased array (to all appearances, it will be produced by the Fazatron-NIIR corporation), and high-precision weapons.
The government commission decided on 26 April 2002 to choose the Sukhoi holding company as the head company to develop and produce the fighter of the fifth generation. The prototype of the PAK FA would take-off in 2006 and that in 2010 the aircraft would be ready for series production. The first deliveries, both for Russian armed forces and for export, would be possible in 2011-12.
The new airplane is being proposed to be brought from the concept design to a prototype series in less than 9 years. Historically, fourth and fifth generation fighters have not been created in less than 15 years. The Russian government has promised to allocate 1.5 billion dollars for the PAK FA through 2010. But the Russian Air Force is receiving less than 200 million dollars a year during this period, and will spend it primarily on other needs.
The prices and sources of funding will determine the destiny of the whole program. To date officials agree that the program will cost $1.5 billion. However, $1.5 billion is the sum needed for creating a new generation of avionics for the fighter (considering the fact that pre-production models of the phased array have already been produced, and will soon be tested). Completion of the AL-41F engine (present readiness is 30 percent) will require, in the opinion of the boss of Rosaviakosmos, 600 - 800 million dollars. Saturn said that launching of production of the AL-41F engine would take $150 million. An improved version of the AL-31F will be used on the aircraft originally (though it is not clear how these heavy motors are reconciled with the concept of a 20-ton fighter). The upgrade of these engines will require expenditures of 1.2-1.5 billion dollars. And finally, designers will have to spend several hundred millions of dollars on creating a new airframe.
According to some reports, India and Russia have agreed to jointly develop this fifth-generation fighter, under a scheduled with entery into service in 2009. This would be the first such joint development venture between the two countries.
08.2007 according to VVS CINC PAK-FA project documentation transferred to plant-manufacturer.
Fifth-generation fighter aircraft would be raised in the air in 2009
Chief of Air Force Colonel General Alexander Zelin said that the fifth generation fighter aircraft would be raised in the air, as planned, in 2009.
«Ê àâãóñòó 2009 ãîäà ìû ïîëó÷èì ëåòíûé ñàìîëåò ïÿòîãî ïîêîëåíèÿ. «By August 2009, we will have a flight version of fifth-generation aircraft. We raise this ac into the air in 2009 », - he said to journalists.
A. Zelin said that by 2009 will be ready three fifth-generation aircraft. «All of them are currently undergoing tests and are more or less ready», - he said.
According to Air Force CINC, «reasons for the failure of plans for the delivery of the aircraft in time I do not see» neither financially nor from an organizational point of view.
06.2009 according to Pogosyan and later Popovkin first prototype will take off in 2009.
24.12.2009 first airfield trials. (Ac nr T-50(KNS))
29.01.2010 11:09-12:06 first flight, Komsomolsk. (Ac nr T-50-1)
06.02(?), 12, 15.02.2010 flights, Komsomolsk, aircarft painted to gray-white camo colors of Russian AF.
From the "Assessing the Sukhoi PAK-FA", Air Power Australia Analysis 2010-01
by Dr Carlo Kopp, SMAIAA, MIEEE, PEng,
Peter Goon, BE (Mech), FTE (USNTPS)
© 2010, Carlo Kopp, Peter Goon
"Analysis of PAK-FA prototype airframe shaping shows a design which has forward fuselage, inlet, upper fuselage, wing and tail surface airframe Very Low Observable (VLO/stealth) shaping which is highly competitive against the US F-22A Raptor and YF-23 ATF designs. Aft and centre lower fuselage, and aft fuselage and nozzle shaping is inferior to the F-22A Raptor and YF-23 ATF designs, sharing the same deficiencies as the F-35 Joint Strike Fighter. This may be an artefact of the use of the interim engines, and uncertainty about aft and beam sector observables performance will remain until later prototypes with the production engine and aft/lower fuselage shaping are available.
Analysis of PAK-FA prototype airframe aerodynamic features shows a design which is superior to all Western equivalents, providing ‘extreme agility’, superior to that of the Su-35S, through much of the flight envelope. This is accomplished by the combined use of 3D thrust vector control of the engine nozzles, all moving tail surfaces, and refined aerodynamic design with relaxed directional static stability and careful mass distribution to control inertial effects. The PAK-FA is fitted with unusually robust high sink rate undercarriage, intended for STOL operations.
Disclosures indicate that the avionic suite and systems fit will be derived from the Su-35S design, with the important difference in the use of an very high power-aperture product X-band multimode primary AESA radar. Five AESA apertures are intended for production PAK-FA aircraft. The highly integrated avionic suite is intended to provide similar data fusion and networking capabilities to the F-22A Raptor.
The available evidence demonstrates at this time that a mature production PAK-FA design has the potential to compete with the F-22A Raptor in VLO performance from key aspects, and will outperform the F-22A Raptor aerodynamically and kinematically. Therefore, from a technological strategy perspective, the PAK-FA renders all legacy US fighter aircraft, and the F-35 Lightning II Joint Strike Fighter, strategically irrelevant and non-viable after the PAK-FA achieves IOC in 2015.
Designed to compete against the F-22 in traditional Beyond Visual Range (BVR) and Within Visual Range (WVR) air combat, the PAK-FA shares all of the key fifth generation attributes until now unique to the F-22 - stealth, supersonic cruise, thrust vectoring, highly integrated avionics and a powerful suite of active and passive sensors. While the PAK-FA firmly qualifies as a fifth generation design, it has two further attributes absent in the extant F-22 design. The first is extreme agility, resulting from advanced aerodynamic design, exceptional thrust/weight ratio performance and three dimensional thrust vectoring integrated with an advanced digital flight control system. The second attribute is exceptional combat persistence, the result of a 25,000 lb internal fuel load. The internal and external weapon payload are likely to be somewhat larger, though comparable to those of the F-22A.
While the basic shaping observed on this first prototype of the PAK-FA will deny it the critical all-aspect stealth performance of the F-22 in BVR air combat and deep penetration, its extreme manoeuvrability/controllability design features, which result in extreme agility, give it the potential to become the most lethal and survivable fighter ever built for air combat engagements.
The tactical impact of a mature production PAK-FA is therefore a loss of the overwhelming advantage provided until now by the F-22A Raptor. Flown against the PAK-FA, a decisive outcome can only be guaranteed by numerical superiority of the F-22A force in theatre.
Once the PAK-FA is deployed within a theatre of operations, especially if it is supported robustly by counter-VLO capable ISR systems, the United States will no longer have the capability to rapidly impose air superiority, or possibly even achieve air superiority. This will not only deny the United States access to an opponent's defended airspace, it also presents the prospect of United States forces being unable to reliably defend in-theatre basing and lines of resupply.
In the broadest of terms, the PAK-FA is a fusion of ideas and design features seen in late model Flanker variants and demonstrators, but incorporating specific stealth shaping features employed previously in the Northrop/MDC YF-23 ATF demonstrator, and the production LM F-22 Raptor. The PAK-FA is clearly a unique Russian design and is neither a copy of the F-22 or the YF-23.
No less importantly, the PAK-FA is by Western standards a low risk design, following the Russian philosophy of “evolutionary” design, rather than the “Big Bang” approach currently favoured in the West, of trying to start from scratch with most or every key portion of the design.
Russian sources indicate that the prototypes will be fitted with a derivative of the existing Su-35S avionic suite to reduce risk and cost. It is likely that this strategy of risk reduction by the use of existing production hardware will apply to other key internal components. The use of the 117S series engine common to the Su-35S in PAK-FA prototypes is a prime example.
Another example is the basic layout or configuration of the PAK-FA airframe design, which is demonstrably based on the T-10 Flanker series, with a large centre fuselage carapace, a pair of long serpentine engine inlet ducts, with inlets beneath a large LEX, the engines mounted in blast resistant tubes, which also provide the means for reacting empennage control surface and TVC loads, and a blended forward fuselage raised above the engine centrelines, not unlike the Flanker and F-14 series. The forward and centre fuselage design is therefore closer to the Flanker and YF-23 than the F-22A. The wing planform is closest to F-22, reflecting design aims in VLO shaping and supersonic cruise performance.
Where the PAK-FA departs most strongly from the earlier Flanker, the F-22 and the YF-23 is in the aft fuselage design, and the moving LEX or Povorotnaya Chast' Naplyva (PChN) design, intended to provide extreme manoeuvrability and controllability and, thus, extreme agility - an attribute absent in the F-22 and YF-23, but extant in some later Flanker variants, demonstrators and prototype programs.
To provide extreme agility, Sukhoi's design team employed all-moving stabilators and canted tail fins, a nodding movable LEX design, and 3D axi-symmetric engine nozzles. The wide spacing of the fully articulated fins and engine nozzles provides a much larger moment arm for both aerodynamic and TVC roll and yaw inputs, than observed with previous designs. While the tail surfaces do not impair observables, the use of axi-symmetric 3D nozzles does, no differently than the fixed axisymmetric nozzle of the F-35 Joint Strike Fighter.
Conversely, the current design may be an expedient development shortcut, with a more refined aft quarter VLO design to appear with the final production engine. The quality of the front quarter VLO design demonstrates that Sukhoi are capable of producing an aft quarter VLO shaping design no worse than the F-22A or YF-23 designs.
The combination of aerodynamic design features for extreme agility, high thrust/weight performance supersonic cruise engines to provide supersonic persistence, and the large combat persistence provided by a large internal fuel load and large weapons loads, make the PAK-FA the best fit to the Boyd “energy manoeuvrability” model yet to be developed.
The extreme agility of the PAK-FA design, when employed harmoniously with the other 5th generation design features, opens up a range of new tactical options, not feasible with established or currently planned Western fighter designs.
Based on analysis of the features and history of the PAK-FA design observed to date, an apt summary of this aircraft would be a High Speed/High Agility Interceptor/Air Dominance Fighter/Persistent Strike/ISR Platform, built for operation from short unprepared FOBs, and readily adapted for aircraft carrier operations.
The forward fuselage is closest in general configuration to the YF-23, especially in the chining, cockpit placement, and hump aft of the cockpit canopy, although the blending of the upper forward fuselage into the upper carapace is more gradual. There are important differences from the YF-23. The chine curvature design rule is purely convex, like the chine design on the F-22A. The nose height is greater, to accommodate an AESA with a much larger aperture than that intended for the YF-23 or F-22A. If flare spots are properly controlled by the application of materials and serrated edge treatments around the canopy, and a good bandpass radome design using a frequency selective multilayer laminate is employed, the shaping related RCS contribution of the forward fuselage in the S/X/Ku-bands will be similar to that observed with the F-22A, YF-23 or F-35.
The Electro-Optical System (OLS) turret employed on the prototype is likely the Su-35S OLS, and is incompatible with a VLO design, as it is a broadband spherical reflector. We can expect to see a faceted VLO fairing similar to that designed for the cancelled F-22A AIRST (Advanced IRST [Image]) in a production PAK-FA configuration.
The conventional pitot-static probes currently mounted around and forward of the cockpit are like the OLS turret, incompatible with a VLO design, and we can also expect to see these replaced with VLO design ports in a production PAK-FA configuration.
The edge aligned movable LEX are readily treated with leading edge absorbers and will not present a major RCS flare spot. The treatment of the movable join will present the principal challenge in this portion of the design. The obtuse angle in the join between the LEX and forward fuselage is characteristic of good design and is very similar to the angles used in the F-22.
The lower fuselage of the prototype displays interesting incongruities. There is an abrupt transition between the carefully sculpted faceting of the inlet nacelles, and the smoothly curved aft engine nacelles and conventional aft fuselage. The faceting strategy is similar to the F-22 design rules, with singly or doubly curved transitions between planes (C. Kopp/Sukhoi image).
The edge aligned trapezoidal main engine inlets are similar in configuration to the F-22, but with important differences. The inlet aspect ratio is different, and the corners are truncated in a manner similar to the YF-23. If properly treated with leading edge inserts and inlet tunnel absorbent materials, the inlet design should yield similar RCS to its US counterparts.
The placement of the engine centrelines well above the inlet centroids, in the manner of the YF-23, results in an inlet tunnel S-bend in the vertical plane. Sukhoi have not disclosed whether an inlet blocker will be employed. Public disclosures on Su-35S inlet treatments claimed a ~15 dB reduction in X-band RCS compared to the untreated inlet tunnels on the Su-27SK. The use of an S-bend in the PAK-FA would permit an increase in the number of surface bounces further increasing attenuation and reducing RCS.
In the S/X/Ku-bands the basic shaping of the forward fuselage will permit the attainment of genuine VLO performance with the application of mature RAS and RAM, where the centre and aft fuselage do not introduce larger RCS contributions from the forward aspect.
The wing design from a planform perspective is closest to the F-22A, and the upper fuselage similar to the YF-23, permitting the achievement of similar RCS performance to these US types, from respective aspects.
Where the PAK-FA falls well short of the F-22A and YF-23 is the shaping design of the lower fuselage and side fuselage, where the general configuration, wing/fuselage join angles, and inlet/engine nacelle join angles introduce similar intractable specular return problems as observed with the F-35 Joint Strike Fighter design. These are inherent in the current shaping design and cannot be significantly improved by materials application. Like the F-35 Joint Strike Fighter, the PAK-FA prototype design will produce a large specular return in any manoeuvre where the lower fuselage is exposed to a threat emitter, and this problem will be prominent from the Ku-band down to the L-band.
The tailboom shaping is reminiscent of the F-22 and F-35 designs, and will not yield significant RCS contributions from the front or aft aspects. In the lower hemisphere, it will suffer penalties due to the insufficiently obtuse join angles between the wings and stabilators, and outer engine nacelles. The upper fuselage fairings which house the all moving vertical tail actuators are well shaped, and the join angles are well chosen. The outward cant of the empennage fins is similar to United States designs, and like the YF-23 tail surfaces, these are fully articulated with the VLO benefit of removing surface impedance discontinuities at the join of a conventional rudder control surface.
The axi-symmetric 3D TVC nozzles present the same RCS problems observed with the fixed axi-symmetric nozzles used in the F-35 JSF [analysis/imagery], and the application of serrated shroud treatments and tailpipe blockers as used with the F-35 JSF will not overcome the inherent limitations of this canonical shaping design. Observed from the aft hemisphere in the L-band through Ku-bands, the PAK-FA prototype configuration will produce to an order of magnitude an equally poor RCS as the F-35 Joint Strike Fighter10.
The centre fuselage beavertail follows a similar chine design rule as the forward fuselage does, and will not present a significant RCS contribution from behind.
If production PAK-FA aircraft employ the same lower and aft fuselage design as the prototype does, they will be susceptible to aft hemisphere and beam aspect threats at depressed angles, operating from the L-band through to the Ku-band, in a manner no different to the F-35 Joint Strike Fighter.
It is worth observing that the unconventional flight control capabilities of the PAK-FA do open up some possibilities, in that they permit manoeuvres such as flat turns, or even turns where the bank angle is opposite to a conventional banking turn. Such manoeuvres permit the PAK-FA to execute, without difficulty or high energy bleed, turns away from beam aspect threats without significant exposure of the problematic lower fuselage, unlike the conventional F-35 JSF which becomes unavoidably susceptible to detection, tracking and missile shots in such geometries. As the PAK-FA will provide a similar supersonic cruise capability to the F-22, its window of vulnerability is very much shorter when attempting to evade a tail aspect threat, and it has a credible capability to defeat missile shots kinematically.
The general configuration of the PAK-FA aft fuselage is as compatible with the style of 2D VLO shaped TVC nozzles used in the F-22A, and integrated with the F119-PW-100 engines, as it is compatible in principle with the superb non-thrust vector aft fuselage design used in the YF-23. The latter remains the benchmark for wideband aft sector VLO fuselage design.
Producing a 3D TVC nozzle design which has similar VLO shaping performance as the F-22A 2D TVC nozzle design is not a trivial task - there is no obvious simple solution to this problem. If the Russians have solved it, it would be a major advance in VLO nozzle design.
From an RCS engineering perspective, the shaping design of the PAK-FA is an excellent first attempt by the Russians to produce a high quality VLO design. The forward fuselage and engine inlet area shaping design is highly competitive against more recent US designs, and with mature high quality RAS and RAM application, have genuine VLO potential. The upper fuselage, wing and tail surface shaping and planform alignment are also competitive against US designs.
The problematic lower and aft fuselage designs, if retained in production aircraft, will deny the PAK-FA the kind of deep penetration capability sought in the design of the F-22A and YF-23.
The only cited RCS performance data was a recent claim by Sukhoi that the PAK-AF will have 1/40 of the RCS of the Su-35S. Unfortunately this was not qualified by threat operating band, aspect, or whether the Su-35S was clean or laden with external stores. The RCS of the Su-35S, head-on in the X-band, has not been disclosed, but given the extensive RAM treatments applied could be as low as 0.5 - 2 m2 for a clean aircraft with no stores. If the latter were true, then the PAK-FA X-band head-on RCS would be of the order of -13 to -19 dBSM. Such performance would be consistent with the shaping design, but not with the application of mature RAM and RAS to same.
Analysis of tactical options, as published in March 2009, assumed a PAK-FA forward sector X-band RCS of about -20 dBSM, which fits the outer envelope of the Sukhoi disclosure almost exactly5,6.
Examination of the publicly displayed PAK-FA prototypes show that this design is a continuation of the highly evolved pedigree of Flanker aerodynamic design. However, as observed in and predicted from the most recent Flanker variant, the Su-35S, and the work done during the deep modernisation program that resulted in this design, Sukhoi have evidently taken the next step by providing the PAK-FA with relaxed static stability in the directional axis.
Open source materials such as high resolution imagery and video camera footage show there are a number of features about the aerodynamic design of the PAK-FA that are different to, but clearly enhancements on the tried and proven aerodynamics of the Flanker family of aircraft, including:
Fully articulated, reduced aspect ratio dorsal fins that are canted outwards. These provide large control power and control authority while minimising drag and side area with the additional LO benefit of the latter.
Articulated LEX sections/control surfaces above and immediately forward of the quite large intakes of the propulsion system.
Main wing leading edge sweep angle of ~46.5° to which the leading edges of the LEX sections and the horizontal stabilisers are edge aligned, with the latter closely nested with the wing trailing edge flaperons.
Large wing area, estimated to be ~840 square feet.
Large leading edge flaps, around 90% span of each of the outboard sections of the main wing.
Large trailing edge flaperons spanning about 60% of each of the outboard sections of the main wing, truncated and blended with the leading edges of the horizontal stabilators.
Large aileron control surfaces of ~30% span of the outboard sections of the main wing.
Prodigious wing/fuselage blending with primary area ruling achieved through shaping of the upper and lower portions of the engine nacelles.
Classic later generation Flanker Boundary Layer Control (BLC) systems in and around the intakes, extending aft along the engine lower nacelles.
The propulsion system intakes are quite large and clearly intended to accommodate thrust growth, possibly the use of ‘ejector nozzle technology’ for increased thrust augmentation (akin to the J58 engine of the SR-71 and more recent DARPA Vulcan program), and overall thermal management, as well as providing additional air for exhaust plume shrouding, the latter for infrared signature control.
Alternate intakes for the propulsion system, as seen on earlier Flankers.
Nominal engine thrust lines are canted outwards about 2° to 3° off the longitudinal centreline, with the engines spaced symmetrically around BL 00, at around 10 feet centre to centre spacing at the nozzle exit planes. This configuration reduces the risk of the rapid onset of large yaw rates at large thrust settings due to single engine in-flight shutdowns, while, when combined with the increased ~60°/sec angular TVC rates observed in the Su-35S design, enhancing the ability of the TVC system to augment/replace aerodynamic flight control inputs, while aiding in the provision of ‘apparent static directional stability’ through dynamic control to replace the normally ‘natural inherent static directional stability’ that has been relaxed.
There has clearly been a concerted effort to establish harmony and complementarities between the inertial properties in each of the aircraft axes, as well as the physical sizing of the control surfaces for each axes. This work has its roots in earlier T-10 Flanker series designs, most recently, the Su-35S.
As seen on the Su-35S, there is no separate, dedicated speed brake control surface, this function being subsumed by differential deployment of control surfaces.
With the undercarriage fully deployed, the primary Nose Landing Gear (NLG) doors are closed with small ancillary doors providing the opening through which the NLG oleo and related dual wheel and steering assembly protrude, thus removing the directionally destabilising effect of the primary doors in the powered approach (PA) configuration.
When deployed, the sizeable Main Landing Gear (MLG) doors are aligned to the longitudinal plane of the aircraft and likely contribute to the static directional stability of the aircraft in the PA configuration.
Observations from the video footage of the first “public” flight include:
The relatively high speed taxi to the hold short line showed very little vertical motion or forward/aft interaction of the undercarriage oleos/tires spring/damper system which suggested the aircraft was likely at a relatively light, mid-fuel/mid centre of gravity (CoG) configuration.
The aircraft flew away from the runway during the take off with no perceptible pitch control input, evidenced by no leading edge displacement of the horizontal stabilisers and no deflection of the TVC nozzles in pitch being observed. This is akin to the F-22A Raptor wherein take off trim and lift off speed are all that are required for the aircraft to unstick off the runway. This contrasts strongly with the F-35 series of designs, where a conventional take off requires an elevator input in the order of 30° LE down to initiate the unstick /rotation process.
Very little leading edge flap deployment, most likely employing the minimal take off trim setting, appeared to be required and no significant deployment of the trailing edge flaps was evident.
During the ground roll, engine nozzles were in the trail position and no vectored input in either the longitudinal or lateral axes was evident.
Take off roll to un-stick was estimated at somewhat less than 1,500 feet, taking some 12 seconds from brake release to rotation speed (Vr).
Rotation and initial climb out appeared smooth, stable and well controlled with increasing rate of climb, with the causally increasing climb angle and climb attitude evident and monotonically climbing within 2 seconds after lift off.
Little coverage of the up and away part of this flight was released into the public domain, though there are multiple reports that the undercarriage was cycled when airborne and some time was allocated for mild side slip and flat turn manoeuvres, along with lateral control excursions to around 45° from wings level flight.
The landing was uneventful with what appeared to be minimum leading and trailing edge flap settings and little, if any, employment of TVC and/or the LEX control surfaces. The pilot held the nose wheel off the runway for approximately 4 seconds after the MLG contacted the runway, with the nose wheel run on to the tarmac coinciding with deployment of the two arrestor drag parachutes. These chutes were released some 10 seconds later, signalling the end of the 14 second ground roll portion of the landing iteration. Overall, the distance of this portion of the landing was estimated at somewhat less than 1,300 feet.
The results of detailed observations and analyses of the material now in the public domain combined with knowledge of the progressive ‘evolutionary and evolving’ development of aerodynamic techniques by Sukhoi over more than two decades, demonstrates that Sukhoi and its supporting team of engineers and scientists have achieved mastery of extreme agility throughout the whole air combat continuum. Since the Su-35S design is already accredited with the title of “extreme agility”, the aerodynamic and kinematic capabilities of the PAK-FA will likely require coining of the term “extreme plus agility” to do them justice.
The introduction of relaxed static directional stability in the PAK-FA design, alone, will ensure that the PAK-FA has the manoeuvrability and controllability capabilities and, thus, the agility that no Western fighter design can provide.
There is only one Western fighter design configuration that, with some upgrades and modification, will be able to approach the PAK-FA in manoeuvrability and controllability capabilities; specifically, the F-22A Raptor. The aerodynamic design of all other US air vehicles precludes such modifications, this including the F-35 Joint Strike Fighter.
Sukhoi will face some interesting design challenges in developing the PAK-FA avionic suite. These will lie in the same areas which have bedevilled US designers in all recent VLO aircraft development projects, specifically in the provision of high capacity avionic cooling, which does not produce infrared hotspots, and in the design of wideband, yet very low RCS radio-frequency apertures for both passive and active sensors, and aircraft datalink/network terminal transceivers.
Russian parliamentary scientific advisor Konstantin Makienko, in a recent media interview, noted that the PAK-FA avionic suite would be used as the basis for technology insertion upgrades on the Su-35S. He also observed that “Not just an active radar but an entire multifunctional integrated radio electronic system that contains five integrated arrays is being developed for PAK FA”.
There have been no prominent disclosures on the PAK-FA cockpit design. It is likely that a derivative of the ergonomically well fashioned Su-35S glass cockpit would be used - this design employs a pair of large AMLCD panels to emulate the projector based arrangement in the F-35, but with more robust fault tolerance, greater simplicity in design, yet similar ease in operation.
Russian sources claim that the new OKB Aviaavtomatika HOTAS control set is likely to be used in the PAK-FA, but no formal disclosures by manufacturers have been made to date.
Like the Su-35S, the PAK-FA will employ a dual mode Glonass/GPS receiver and Kalman filter based inertial navigation suite, with an RLG.
As with the Su-35S, the PAK-FA will carry datalinks for bi-directional data transfers. There have been no disclosures at this time on the datalink terminals or waveforms intended.
A number of Russian sources have commented on the use of “data fusion” in the PAK-FA avionic design, a technique which is used currently in the F-22A and intended for the F-35."
According to the Commander of the Russian Air Force, Lieutenant General Viktor Bondarev on 12.2012 "PAK FA successfully flies, three aircraft are being tested in Zhukovsky, one aircraft is being tested at the factory. And fifth aircraft near the completion." Awaiting for completion of three other aircraft.
State tests are assigned at GLITs beginning March 2013 till the end of 2014-2015.