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MILITARY SUKHOI T-50

Piotr Butowski reports on the latest developments to the Sukhoi T-SO fighter

ne ve months havepassed Since themaiden flight of Russia'sf fth generat on fighter,the Sukhol T-SO.

developed within the PAK FAprogramme. In December 2009T-SQ-KNS, a non-flying example,

0211

Overall shape of the T-SO isnot surprisingly an evolutionof the Flanker, adapted forthe requirements of stealthtechnology, supersonic cruisespeed and agility. In comparisonto the Flanker the T-SO's twoengines are mounted furtherapart to allow weapon bays tobe positioned between them.Vertical tail surfaces are scaleddown, single-piece and all­moving. The fuselage has anangular shape to reduce radarcross-section and the wing isblended with canards and the tailplanes. These design aspectscombined with a wide fuselagecreates a uniform aerodynamic

Popovkin, thefirst deputy of the

Russian Defence Ministerfor armament purchases,

announced that in 2013, after thefirst stage of the aircraft's trials arecomplete, the Ministry of Defencewill buy an initial batch of six toten T-SOs for military trials.

Procurement of aircraft foroperational units will beginin 2016. "We estimate theAir Force's need for 60~100aircraft [through to 2020]," saidPopovkin. Colonel GeneralAlexander Zelin Commander~in~

Chief of the Russian Air Force,then announced future orders bythe Air Force for "more than 60fighters" (a number within theNational Armament Programmethrough to 2020).

The announcements made todate seem to be realistic becausethe PAK FA programme hasundisturbed funding and withonly minor delays all programmetimelines previously announcedwill be kept.

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PAK FA's SupersonicEnvironment

performance,flight control and

navigation systems,aircraft installations and engine

testing. Aircraft three (T-SO-3) wiltfly in 2011 and aircraft four (T-SO­4) in 2012. Both will be equippedwith a full missions system suite;neither T-50-1 or T-SO-2 arefitted with radar or other missionsystems.

Two other non-flying examplesare undergoing tests. T-50-KNS(Kompleksnyi Naturnyi Stend,Complex Full-scale Stand) isused for synchronization of allconstruction components, andT-SO-O for static stress tests.

Factory trials of the T-SOprototypes will continue until2012 at Zhukovsky (the Russianair industry test centre) followedby state trials at the Ministry ofDefence test centre at Akhtubinsk.

During a press conferenceat Farnborough InternationalAirshow in July 2010, MikhailPogosyan, head of the SukhoiCompany, stated that the T-50test programme comprises morethan 2,000 test flights. He alsoannounced plans to displaythe T-SO at the MAKS air showat Zhukovsky in August 2011.Pogosyan also said that the fifthgeneration fighter "exceedspreceding aircraft three times interms of effectiveness". The PAKFA will be more expensive thancurrent fourth generation aircraft,mainly because of the costs ofits new systems, but "for exportit will be much cheaper than therivals," he said.

In June 2010 Vladimir

The second prototype, T-SO-2,was expected to fly by the endof 201 0, but its maiden flight isdelayed and is likely to take placein late January at Komsomolsk­on-Amur.

Aircraft T-SO-1 and T-SO-2will be used for handling and

VladimirPutin

watched afour-minute

display by T-SO-1at Zhukovsky on June

17; its 16th flight. Fivepractice flights were made

during the days leading up to thedisplay.

A longer break in the testflying programme took placebetween mid June and August,a period that was lengthened bythe terrible forest and moor firesaround Moscow.

In late August, T-SO-1 returnedto the air, conducting intensivepreparations for a display thattook place on August 31 whenthe aircraft was demonstratedat Zhukovsky to a delegationfrom Hindustan Aeronautics Ltd(HAL) and the Indian Ministryof Defence. By the end ofNovember 2010, aircraft T-SO-1had made 40 flights.

performedhigh-speed

taxiing on therunway at the

Komsomolsk-on­Amur plant, and then

on January 29, 2010,aircraft T-SO-1 made the

maiden flight.During a two-week break

from test flying, T-SO-1 waspainted in a three-colourcamouflage, with side number51. It flew again on February 12,the first of a series of six flightsthat was completed on March26, after which it was dismantledand airlifted onboard an An-124transport aircraft (with T-SO-KNS)to Zhukovsky near Moscow onApril 8. The aircraft was re­assembled and made its first flightat Zhukovsky (its seventh flight)on April 29. Subsequent flightsfollowed on May 14, May 25 andJune 3.

Prime Minister of Russia

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MILITARY SUKHOI T-50

surface that easily adapts to allflight envelopes.

Fourth generation fightersIke the Flanker reach supersonICspeed for on Iy short periodsof time and their typical flightenvelopes lay beneath the speedof sound. By comparison the T-SOnot only cruises at supersonicspeed (a capability known assupercrUlse). but also and mostimportantly manoeuvres andfights at supersonic speed. Thesecharactenstics impose significantrequirements on the aircraft'saerodynamic layout, the enginesmust be capable of generating

igh thrust without afterburnerand Its mission systems must reactquickly to threats.

The most characteristicfeature of the T-SO's aerodynamIclayout are the forward stretchedwing· root extensions, endedby large moving flaps on theleading edge, connected withthe wings by elastic couplings.The extens ons shift the centreof pressure forward, increasingthe static Instability, which isespec ally important in supersonicfI ght, when the centre of pressurenaturally shifts aft and the aircraftbecomes too stable and lessmanoeuvrable. Static instabilItyof the T-SO amounts to 10-12%;by comparison, the Su-27MFlanker has 5-6%, and the Su-27s statically neutral. Thanks tohigh static instability the T-50 canmanoeuvre at supersonic speedmuch bett:er than any previoustIghter

The T-SO has triangular wingsWIth a leading edge sweep of48 and a reverse sweep to thetrai Ing edge of _10 c

, smoothlyblending into a very broad1ft-producing fuselage. The

w'ngtlps are cut. There IS a longnose flap on the leading edgeand two sections of flaperons onthe trailing edge. Single-piecehonzontal tail planes are similar inshape to the wings. Vertical tailsurfaces are also single piece, arerelatIve y small planes set at anobtuse angle of 26

Moving engine nozzlesfunctIon in the same way as theSu-30MKI Flanker: they move inone plane (up and down), butthe planes of movement aretl ted from vertical: the right oneto the right, and the left one tothe left. Thus the nozzles movealong the arms of the V letter andprovide control in all directions.All control surfaces and enginenozzle movements are controlledby aKSU-50 (KompleksnayaSistema Upravlenya) digital flightcontrol system, developed by theAv onlka Company of Moscow.Thanks to extended wing high-liftdevices and vanable thrust vector,

02 1 1

the aircraft is capable of operatingfrom short airstrips.

The T-SO aircraft is poweredby two Saturn AL-41 Fl (izdeliye117) engines, rated at 15 tons(147kN/33.046Ib) of thrust each.It IS a thorough upgrade of theAL-31 F engine used by the 5u-27with a larger diameter fan, newhlgh- and low-pressure turbines,upgraded combustion chamberand a new FADEC control system,integrated with the aircraft'scontrol system. The AL-41 F1engines will be the power plantof the PAK FA fighters at leastuntil 2020. Production of anew engine, rated at 18 tons(176.5kN/39.679Ib) of thrust isexpected at a later date.

Survivabilitythr()ugh 'S~~al~h'

According to publishedassessments a tenfold reductionof an aircraft's radar cross sectionIncreases its survivability duringthe mission by 40%. AlexanderDavidenko, Chief Designer ofthe PAK FA at the Sukhoi designbureau says, that the radar crosssection of previous generationaircraft, for example the 5u-27amounts to 12 square metres, andthe American F·22 - some 0.3-0.4square metres. The PAK FA willbe in this respect "not worse thanthe F-22, but close to it", saysDavidenko, Meaning that theradar cross section of the PAK FAwi I be at least 30 times smaller

than that of the 5u-27, hence itssurvivability is twice greater.

Tl,e fuselage of the T-SO isshaped by facets placed atdifferent angles; in its constructionspecial materials are used.Weapon bay and wheel welldoors have 'toothed' edges andthe production version will becovered with radiation absorbingskin. According to AlexanderDavidenko, the share ofcomposites in the airframe weightamounts to 25% and in the aircraftoverall,70%,

3

The most important designsolution used to reduce the T-50'sradar cross section is the use ofinternal weapon bays to carry itsbasic weapons load. Two 1.0m(3ft 3in) wide and 4.6m (15ft 1in)long bays, positioned in tandem,occupy the entire length of thefuselage ventral surface. from thenose wheel well to the enginenozzles housed between theengines. Both bays will carrymedium- and long range air-to-aIrmissiles and precision-guided air­to-ground munitions

However the airCI ~ft also needsshort range a r-tO-alr m'sSl es forclose-air combat. The seeker ofsuch a missile must lock on tothe target before aunch, wh eM ismpossible, It the mIssile S carr:edin a main fuselage weapon baybecause the bay's walls obscurethe miss Ie's seeker.

Tl,eoretlcal y, a short rangemissile might be launched 'blind'controlled by autopi ot accordl"gto prel minary target ndlcaticand thel Jock on to the targetin flighl But in practice this

4

1T-50-' ts·n e f g tfmmKomsorr. k on-Am r pant 0

January 29 L 'f:fJ 2 T·50-1 onfoal approach to Komsomf)lsk.- nAmUf. The r ght 5 de ob ong underwing fairing IS easily seen near hefuselage 3 The T SO's tandeminternal weapon bays can c early beseen under the fuselage extendingfrom a forward point adjacent theengine mlets to the engne nozzles.4 Two drag chutes help to slo......T-SO-1 on OIl'OUl after land n9 onthe runwa}> t K soma sk-o -ArT'UI

fa oWing the ry! e·s m den 19 t aJanuary 29 ''If'1:fl

the COCkpit but at east threesensors, search ng the spacearound the a rcraft. Geofjzika- Vbased In Moscow IS develop·nga new helmet·mounted sight anddsplay (HMSD) for the PAK FA.

A fllght-nav·gation system,central computer and the manmachine Interface are be ngdeveloped at the RPKB deSignbureau at Ramenskoye.

The T-50 cockpit differs verylittle from the 5u·35 and isequipped with two large 380mm(15 inch) LCD displays and threesmaller control panel displayspositioned throughout thecockpit The only difference·s anew wide-ang e (30x22°) ShKAI 5head-up d splay made by :heElektroavtomat lea Companybased in St Petersburg theSu-35 has a more conventlonaIKSh-1 M I1UD made by the RPKBCompany)

Developrrent work on theSh121 radar and other sensors songoing. The first experimentaexample of the forward Sh12 1

radar antenna for the PAK FAwas made in November 2008and displayed by the TikhomirovNIIP institute at the August 2009MAKS airshow. Three examplesof the radar are currentlyundergoing Jab trials; in 20112012 two of them, along withother m SSton systems wi befitted to airuaft ....·50--3 and T-50-4

SUKHOI T-50 MILITARY

2

any position around the aircraft.Sensors that monitor the airspace and ground surface aroulldthe aircraft Will be used with theaircraft's high manoeuvrabIlity,and various weapons toaccomplish this.

Another essential componentof all-aspect awareness is theaircraft's ability to link into asecure digital communicationnetwork. To this end the PAK FAwill have secure communicationlinks to enable the exchange ofdata with other aircraft, airborneand ground-based commandpoints. The Russian designbureaus are working on thiSrequirement, but unfortunatelyno more information is currentlyavailable

The degree of systemintegration under design for thePAK FA is much higher than thatof the Su-27 Flanker which hasthe radar, electro-optical (EO)sight and the helmet-mountedsight integrated with each other,enabling for example. the EOsight to feed target coordinates tothe radar.

PAK FA will have a significantlyenhanced sensor suite and theSh121 radar system will have fiveantennas (six if the millimetreradar housed in a pod is counted),but not one in the nose

The Atoll EO system is nolonger a single 'egg' in front of

The disadvantage of theconformal weapon bay s theincrease of the aircraft's mid­section, but the advantage is thefuselage inner space freed upthat can for example be used tocarry fuel

All aspect Awarenessand Engag~:.f.1ent

The task of the PAK FA is tofight all kinds of tactical targetsin the air, on the ground and onthe surface of the ocean, from

way S 'leffect ve: n a dy1 afT'lcose a .. combat scel"'a,.,o t"'ere

w be nsuffc ent ~ M and theprobab I ty of m ss g the targetw be very high.

Designers of the T-SO haveused so-called 'quick bays (Bystryiotsek n Russian) in the shape ofoblong under wing fairings, nearthe fuselage to carry short rangemissiles for the close air combat.In comparison the F-22 Raptorhas bays especially designed to~rry Sidewinder missiles located

n t e $ des of the fuselage

02 "1 35

MILITARY SUKHOI T-SO

2

dnggea thefie • 0 tl- retract seque~ce

PAK FA nrototype T-50-1 makesa sp ted departure f C1) J,e

.'.ay at Zhukovsky Sec:ndsfr m touch down at Zhukovsky, this

'ew of the T-50- 1 shows the small<;;Ingle piece vertical tail surfaces

s 1 at an obtuse angle of 26'" Atest pi at climbs into the cockpIt d

so- 1 at Zhukovsky on June 17 fe'C€'11cnstrat;-:-n i ght for the P, me

M s"erofRu saVlad-m-rF,tn

4L..._.;..... ~ ~ _____=

: 36 . ••...... .02.11"'..-

known in Russia as the 'opticalarchitecture' of the fighter, isbeing developed.

A precise configuration of theAtoll system is nof knowP. butit will consist of at least threesensors, The first, typical ofprevious Russian fighters, is asight mounted in the 'egg' onthe starboard Side in fro. t of thecockpit. The second s the upperhemisphere observation devicemounted on the fuselage aft ofthe cockpit and the third is forthe lower hemisphere (groundsurface) observation devicein development for UOMZ bythe Vav.lov OptiC InstItute at 5tPetersburg. The lower sensor wiprobably be pod~mountedbutthis is unconfirmed.

All three sensors are activeand passive in the infrared band(not just passive I ke previous

SUKHOI T-SO MILITARY

the MiG-29 Fulcrum and 5u-27Flanker fighters were designed byNPO Geofizika, and produced bythe UOMZ plant at Yekaterinburg.In the 19905 Geofizika broke upinto several smaller companiesand largely lost its potential,while UOMZ was growing. In2002 UOMZ, employing someGeofizika employees openedits engineenng division Ural­Geofizika in Moscow, whichcurrently designs new EOsights. Ural~Geofizika is themain contractor of the Atollprogramme, within which thePAK FA:s electro-optical system,

supplied by NPP Istok of Fryazino(the X-band) and NPP Pulsar ofMoscow (the L-band).

Chief antenna designer atNIIP, Anatoly 5inani claims, thatin series production the price ofan X-band module will amount to20,000-25,000 roubles (£450-550)each, and the front radar antennahas more than 1,500 modules.Side antennas are much smaller.X-band modules are biased toGallium Arsenide (GaAs), and theL-band modules are biased tosilicon.

Thirty years ago, the infraredsearch and track devices for

FEATURES OF THE PAK FA

The complete Sh121 radarsystem has five antennas: theforward X-band (centimetrewavelength) two smaller X-band,situated on the Sides of theforward antenna and two L-band(decametre wavelength) in thewing leading edges. Additionallya Ka-band antenna (millimetrewavelength) may be carr-edn a pod. The NIIP instituteemphas ses that the productiontechnology and componentsutilized in antenna constructionare Russian; transceiver moduleswIll be produced by the GRPZplant at Ryazan from elements

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4

3

5

EVERYTHING NEWThe PAK FA is a giant programme of the-Russian aviation industry,involving several hundreds of companies, developing and integrating newsystems, materials and technologiesNPP Zvezda of Tomi/ino near Moscow is developing the new K-36D-5ejection seat especially for the PAK FA (as early as 2009, the companysupplied two experimental seats for T-SO prototypes). Zvezda alsosupplies the SOZhE-50 (Sistema Obespecheniya ZhiznedeyatelnostiEkipazha) system, comprising the oxygen and anti-G systems, flight suitand helmet.Test pilots flying the T-50 currently use the ZSh7 helmet, which will bereplaced by the new, cheaper, lighter and more durable Z5h 10 variant.PAK FA uses a new auxiliary power unit developed by the AerosilaCompany of Stupino.Even the main 1,050mm diameter and 365mm-wide wheel tyres are newmanufactured by the Sibur company.

2

Company of Kaluga and isintegrated with the Sh121 radarsystem. The Vympel Companyin Moscow is developing theUV-SO, a launcher intended forconventional thermal and radardecoys, as well as single use ECMtransmitters; all of SOmm (2 inches)calibre.

The MKB Vympel designbureau in Moscow is developingall ofthe missiles and internalmissile launchers for PAK FA.

A typical weapon load forair-to-air missions consists of fourmedium range K-77M missilesand two short range K-74M2s.The K-77M missile is currentlyundergoing trials and will soon

examples), and can track andengage multiple air and groundtargets simultaneously. Evenless is known about the T-SO'sself-defence system. Certainlythe antennas of the Sh121 systemand the Atoll EO sensors will beutilized. and probably four lasersensors mounted on the aircraft,covenng 3600 In azimuth.

Information collected andprocessed will be used for threatassessment, turning on jammingdevices or launching decoys andgiv ng recommendations to thepIlot.

The PAK FA's electronicjamming system is reportedlybeing developed by the KNIRTI

38 0211

the programme is vital forInvestment and the order isvalued by the Russian authorit e_so much so that an Ind-andelegation was Invited fortaxiing trials of the T-50-KNS atKomsomolsk on Amur as earlyas December 2009 In the futureRussia counts on se ling an exportversion of the PAK FA (PMF) tocountries currently operating theSu-30MKI (Malaysia and Algeria),and initial talks were heldwith Indonesia.

A gOOd e~ tupper fuse age and the forwardof the w I"\g 2 Good rear lew sho

f --50--1 3 Compute -generatedmage of the PAK FA:s cockp t • P

vIews h-s latest mount 5 Yun Be yl,head of the NIIP radar des'gn bureau(nght) and Anatoly 5manl, head of theantenna division at NIIP together withthe first test example of a front AESAantenna for the Sh121 adar systefTIP,otl Butowsk 6 The maximum Size fweapon to be carned Ins de the weaJ.= nbays IS 4,2(X) x 400 x 400mm 165 x 6x 16 .nches) and these are the exad mens ons of the new modular ~M

a Ho--ground m ss e w th folded wand f ns. Severa seeke~ are ava ab efOf the Kh-38M Inc ud ng sam-actlveaser, act ve radar and nfrared as weas a satellite navIgation receive. AKh-38M .....eighs up to 520kg (235Ib)Including a 2SOkg (114Ib) warhead. Themissile's maximum range is 40km (25miles), Potr Butowskl 7 A drawing fromVympel of the UVKU (Unlfitsirovan oyeVnutrifyuzelazhnoye KatapultnoyeUstroystvo) uni-f ed ntema catapultauncher. Vympe 8 The Raduga m edes gn bu~eau m atu zed :s Kh )8antl·'adar m ss e above nto the KhSBU5hK version e ow to fit ins de ePAK FA's -nterna ba Raduga9 FaMard stretched w ng-rootextens ons have arge moving flaps nthe leading edge, and itre connectedWith the wings by east c couplings

SUKHOI T-SO MILITARY

9

and the preliminary design willbe ready within 18 months. Aseries of contracts will follow tocover the next stages of the PMFprogramme. India s expected toproduce 200-250 aircraft

Indian participation in

25 tons (55,11 Sib)

4.8m (15ft 9in)

5,Om (16ft 4m)

15 tons (147kN/33,046Ib)

Mach 1.3

19.7m (64ft 7in)

Engine thrust---Maximum speed

Cruise speed

Maximum range

Nominal take-off weight

Maximu~m~~~~~~~~_~~~£:~~i==~-= ~

T-SO PROVISIONAL SPECIFICATIONlength (without probe)

Wingspan

Height

Undercarriage track

of a twin-seat variant and theintegration of an advanced enginewith higher thrust at a later stage."A week before, the chairman ofHAL Ashok Nayak told the RussianRIA NovoStl news agency thatthe contrat. value is 5295 mi lion

7

8

6= ---e-o---~"T'"-~~-----e ter ser"es product on and theK 74M2 s yet tc oJ dergo flighttests

AIr-to-ground weapons includethe Kh-58UShK anti-radiationmissIle which is due to enterseries production in 2011, themodular universal Kh-38M missileIS completing trials and theKAB-SOOS guided bomb recentlyentered production, two others,the KAB-5OOM ann UAB-250 willto low.

The a crah may carry a heavierarmament oad on four underw n9 py ons; two under each wingbut such a weapons load is onlyfeas ble on miSSlors not requil ingstealth,

Other new large tacticalmunitions, currently entering ordue to enter production in the nextyea~ are the upgraded Kh-31 PManti-radiation m ssi e Kh-35Uand Kh-59MK antl-shlp missi esand prec s'on-gu ded stand-off1(h..59M2 mss es Further Onto

e future the PAK FA w receivee t rety new ong medum andwort range a' to-a r rTl SSI es

nc Ian Thre -j

Negotiations about Indian)artlClpation in the PAK FA)(fxramme have been ongoingo nca y tel"'l years For the

.t t me a comn on RlJssian­nc a f ghter became the

t e of ta ks between the':Wo countr es Ju e 2001 InJan ary 2003, RUSSIa md Ind as gned the etter of Intention,and n October 2007 s gned anInter-governmental agreementabout common development ofthe fifth generation fighter aircraftbased on Sukhol's design. Themost recent step was made onDecember 21,201010 New Delhi,where Hindustan Aeronautics ltdand Sukhoi with Rosoboronexport5 gned a contract for preliminarydes :10 of the a rcraft In thecontract document wr nen inEng sh, the 0 nt fighter IS calledthe PerspectIve MultI-role Fighter(PMF) which is a dIrect (andincorrect) translation of its Russian<'lrrnnym PMI or PerspektivnyiMnogofunktsionalnyi lstrebitelused by Sukhoi for the PAKFA's export derivative. Thecorrect trans at on IS Future (orProspective) Muhirole Fighter.

An official Ind an MoD pressre ease referred to the Sukhoi T-50as a 'techno ogy demonstrator"made no ment on of thiSdeSignation and stated that thePMF will be modified "to meetIAF specificatIons which are muchmore stringent"

The press release also sayshat "programme options include

th design and development

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