Category Soviet x-plenes

Purpose: This was intended to be the ultimate biplane/monoplane fighter.

Design Bureau: OKB-30, chief designer VV Shevchenko

Dismissed by Shavrov in a single line, the IS-3 and IS-4 were the last of Shevchenko’s con­vertible biplane/monoplane projects. No IS-3 documents have been found, but brief details and a three-view drawing exist of the IS-4. Unlike its predecessors, this was a ‘clean sheet ofpaper’ aircraft, an optimised fuselage fitted with shutters to cover the retracted lower wing and landing gear. The latter was of the nosewheel type, the cockpit was en­
closed, and armament was to be the same as the IS-2. The engine selected was Klimov’s M-120, with three six-cylinder cylinder blocks of VK-105 type spaced at 120°, rated at l,800hp. When it was clear that this engine would not be ready Shevchenko reluctantly switched to the equally massive AM-37 Vee – 12, rated at l,380hp. In about 1942 he revised the IS-4 so that it would have been powered by a 2,000hp M-71F radial, and would have been fitted with slats on the upper wing to eliminate tail buffet. No photographs of the IS-4 have been found, though two documents insist that it was built and one even states that it flew.

Little need be added, beyond the report that, despite the considerable increase in weight over the previous IS fighters, the wings were smaller. Even with slats it is difficult to see how the landing speed could have been slower. In the conditions prevailing during the War it is stretching credulity to believe that this aircraft could have been built.

Shevchenko persisted with his biplane/ monoplane idea too long. His last project was the IS-14 of 1947, a jet with monoplane wings which not only were pivoted to vary the sweepback up to 61° but could also (by means unstated) vary the span.

Purpose: To modify a tactical fighter to have a variable-sweep wing.

Design Bureau: OKB-51 of P O Sukhoi, Moscow.

Spurred by the USAF/USN TFX programme, Sukhoi (and later Mikoyan) researched air­craft with variable sweepback, also called VG, variable-geometry, ‘swing wings’. Exten­sive model testing began at CAHI (TsAGI) in 1963. In early 1965 Sukhoi OKB Deputy N G Zyrin was appointed Chief Designer of the project, with V Krylov team leader. To test full-scale wings the OKB-51 factory selected a production Su-7BM which it had already been using for a year to test other advances. L Moi – seyshchikov was appointed chief flight-test engineer. Modification of the aircraft took place in January-July 1966, and Vladimir Ilyushin made the first flight on 2nd August 1966. Later LII pilots evaluated the aircraft, and on 9th July 1967 OKB pilot Evgeny Kuku – shev flew it publicly at the Domodyedovo air display. Testing was completed at the end of
1967, and though this was clearly an interim aircraft the Council of Ministers decreed that series production should begin in 1969. Unex­pectedly, derived versions remained in pro­duction to 1991, over 2,000 being delivered.

It was by no means certain that an existing wing could be modified with variable sweep – back. The problem was to minimise weight growth whilst at the same time almost elimi­nating longitudinal shift in centre of pressure (wing lift) and centre of gravity. The original wing had the considerable leading-edge angle of 63°, matched to the supersonic max­imum speed attainable. The intention was to enable the wing to pivot forward, to increase span and lift at low speeds. Doing so would naturally move the centre of pressure for­wards, and at the same time it would also move the centre of gravity forwards. The ob­jective was to make these cancel out. This was achieved by pivoting only the outer 4.5m (14ft 9in), placing the pivots close behind the main landing gear in a region well able to dif­fuse the concentrated loads into the struc­
ture. Each outer panel was driven hydrauli­cally forward to a minimum sweep of 30°. Fol­lowing tunnel testing of models, three sections of slat were added over almost the whole span of each pivoted leading edge. In­board of the pivot the existing fence was made deeper and extended under the lead­ing edge to serve as a stores pylon (plumbed for a tank). Among structural changes, the upper and lower skins were each reinforced between the fence and flap by pairs of axial stiffeners (thus, eight in all).

Though empty weight was increased from 8,410kg (18,541 Ib) to the figure given below, and internal fuel was reduced by 404 litres (89 Imperial gallons), flying at 30° sweep extend­ed both range and endurance, and enabled much heavier external loads to be lifted from short fields. Pilots reported very favourably on all aspects of handling, except for the fact that at extreme angles of attack there was no stall­warning buffet.

Purpose: to modify established aircraft for experimental purposes.

Design Bureau: OKB of A S Yakovlev, evacuated to Factory No 153 at Novosibirsk until in late 1944 it returned to Factory 115 on Leningradskii Prospekt, Moscow.

Fromthepioneer Y ak-1 (I-26)fighterY ako vlev derived the UTI-26 two-seat trainer, which in turn was ‘reverse-engineered’ into the Yak-7 fighter. Numerous special variants tested long-range tankage, different engines and ar­mament, and many experimental fits.

Two series Yak-7B fighters were set aside for testing pressurized cockpits. One, No 08­05, was fitted with a Shcherbakov cockpit completely encased in rubber and with a lightweight canopy giving a much better view than that of the pressurized Polikarpov bi­
planes. The other, with bold white-bordered national insignia, had a hermetically sealed metal (0.8mm AMTs aluminium alloy) cock­pit with a heavily framed sliding canopy. In each case the pressurization to 0.2kg/cm2 (2.85 lb/in2) was by an engine-driven blower. Both were designated Yak-7GK.

The Yak UTI-26PVRD again repeated re­search done with a Polikarpo v biplane, in this case the I-153/2DM-4. The DM-4 family were the ultimate types of ramjet developed by IA Merkulov. The final DM-4S had a diameter of 500mm (1ft 7%in), a length of 2.3m (7ft 61/2in) and weight of 45kg (99Ib). The two to­gether burned ordinary petrol (gasoline) from the main aircraft tanks at the rate of 24kg (53 Ib) per minute. The test aircraft had been the UTI-26-2, the second prototype two – seater. The rear cockpit was re-equipped for
a test observer, and the main engine was changed to a l,260hp M-105PF. The pilot could switch fuel to the ramjets and press an ignition button to boost speed from 494km/h (307mph) to 513km/h (319mph) at sea level and to 633km/h (393mph) at 7,300m (23,950ft). The trouble was, though these speeds were a slight improvement over the basic aircraft, for most ofthe mission the ram­jets were dead weight and offered consider­able extra drag, reducing speed to 460km/h (286mph) at sea level and 564km/h (339mph) at 6km (19,685ft). The ramjets were first fitted to this aircraft in 1942, but they moved the centre of gravity too far forward and caused fuel leaks because of combustion vibration. The aircraft was put on one side until on 15 th May 1944 SNAnokhin began a proper LIl – NKAP test programme. It was judged that the ramjets were not worth having.

Unfortunately, the only known photograph of the Yak-7L is a head-on view. This merely shows that the leading edge of the wing of this aircraft was quite sharp (ie, of small ra­dius) and that the aerofoil profile was almost symmetric except towards the root where, like the wing ofthe North American P-51 Mus­tang, it sloped downwards. The letter L in the designation stood for Laminarnyi (laminar). As in the Mustang wing, the maximum thick­ness was at almost 40 per cent chord. Proba­bly influenced by the American fighter, this one-off aircraft is unlikely to have flown be­fore 1943, but the date on the official photo­graph is unreadable.

Photograph on the opposite page: Yak-7GK.

This page, above and below: Two views of UTI-26PVRD.

The fastest Yak piston-engined fighter was the Yak-3RD. The Yak-3 was smaller than any other major fighter of the Second World War, and the standard aircraft, powered by the l,260hp VK-105PF2, had a maximum speed of 646km/h (401 mph) at around 4km (13,120ft). The RD was a normal series air­craft (Saratov-built No 18-20) fitted with an RD-1 rocket engine in the tail. Developed by

V P Glushko, this engine was a pilot-control­lable single-chamber unit fed by pumps dri­ven by the main engine with 50kg (1 lOlb) of kerosene and 200kg (441 Ib) of concentrated nitric acid, supplied from tanks in the wings. Most photographs show this red-painted air­craft with the thrust chamber replaced by a pointed tailcone. The rudder was increased in chord to compensate for loss of the lower portion, and the elevators were cut off at the root and skinned with Dl alloy. OKB test pilot

V L Rastorguyev began flight testing on 22nd December 1944. The RD-1 fitted was No 009; this proved to be unreliable, and also failed to give its brochure thrust until the aircraft had climbed to about 6,500m (21,325ft). It was re­placed by an RD-lKhZ (No018), with hyper – golic chemical ignition. A level speed of 782km/h (486mph) was then recorded at 7,800m (25,590ft), but malfunctions contin­ued. On 14th May 1945 there was an explo­sion during a ground start. Flying resumed on 14th August 1945, and on the following day the kerosene pipe fractured. A day later (16th August), after the rocket had been shut down after a maximum-speed run, the aircraft was observed gradually to pitch over and dive into the ground, Rastorguyev being killed. The cause was never established.

The designation Yak-9P was used twice. The first was a variant with a ShVAK cannon (Pushechnyi) replacing the usual 12.7mm UBS above the engine. The second use of the designation came in 1946, when it was ap­plied to two of the first Yak-9 fighters built at Factory No 166 at Omsk, Nos 0I-03 and 0I-04. These were completed with newly designed all-metal wings, because there was no longer a shortage of light alloys. They were exhaus­tively tested by Yuri A Antipov and VI Ivanov throughout July 1946, and later ten pre-pro­duction aircraft were produced at Factory No 153 at Novosibirsk. A surprising amount of effort was put into perfecting an upgraded all­metal Yak-9, because – despite the immi­nence ofjet fighters – no fewer than 772 were built at Factory 153, ending in March 1948. The photo shows the tail of P0415313, with special rudder and elevator instrumentation and a side-thrust rocket attached by a frame to the rear fuselage.

Purpose: To test rocket engine in flight. Design Bureau: B I Cheranovskii.

The BICh-11 was designed in 1931 as a bungee-launched glider to see if the concept of using wingtip rudders could be made to work. The glides may have been too brief to be useful, because in 1932 Cheranovskii added a small British engine more powerful than the Tomtit used for BICh-3. In 1933 this aircraft was selected by MosGIRD, the Moscow-based experimental rocket-engine
group, as a suitable test-bed with which to fly a small liquid-propellant rocket engine, which began bench-testing on 18th March 1933. The aircraft was again modified, with the rocket engine(s) and their supply and control system and a new wing of increased span. It was then judged that the propulsion system was too dangerous to fly. Note: some accounts say the piston engine was installed after the removal of the rocket engine(s), but drawings show the piston-engined aircraft to have had the original wing.

The BICh-11 was another wooden aircraft with fabric covering, with a single seat, hinged canopy and trailing-edge elevators and ailerons. It appears to have had no land­ing gear other than a centreline skid. On the wingtips were rudders, under which were skids. In its powered form the engine was an ABC Scorpion with two air-cooled cylinders, rated at 27/35hp. The rocket engine was the GIRD OR-2, designed by a team led by FATsander, with a single thrust chamber burning petrol (gasoline) and liquid oxygen.

Purpose: To evaluate a fighter with APK recoilless cannon.

Design Bureau: Team led by Dmitrii PavlovichGrigorovich, inVT(internal prison) run by OGPU (secret police, later NKVD) at Factory No 39.

The story of the development in the Soviet Union of large-calibre recoilless guns, under the leadership of L V Kurchevskii, is outlined in the entry on the Tupolev ANT-23. By the end of the 1920s design bureaux were receiv­ing contracts for experimental fighters de­signed to be armed with such weapons. In late 1929 Grigorovich was sent to Central Construction Bureau 7, which was really Hangar 7 at Factory 39, an OGPU secure prison for designers. Here he led the design of the Z, a secret monoplane to be armed with two 76.2mm (Sin) APK-4 guns. To speed con­struction the powerplant group and forward fuselage of the first prototype were the same as those of the Polikarpov I-5, which was also built in Hangar 7. The complete aircraft, called I-Z (Fighter Z) was flown by Benedikt Bukhgol’ts in (it is believed) early May 1931. It was inspected by Stalin, Voroshilov, Molotov and others on 6th July 1931. Subsequently a small series of21 production I-Z fighters were produced at GAZ No 39. These were still re­garded as experimental. In February/March 1933 aircraft No 39009 was placed on a high
platform and used for firing trials, and in Sep­tember 1933 No 39010 underwent NIl-WS testing. Two of these aircraft were later used in Zveno trials, as described under Vakhmistrov. In 1934-35 Factory No 135 at Kharkov built a further 72, with modifications, designated IP-1. These saw only limited use, partly because of difficult spin recovery, but were not considered as experimental.

At this time monoplanes were still struc­turally difficult, and the wing, though of torch-welded stainless (Enerzh-6) lattice con­struction, still needed underwing bracing to the fixed landing gears. Apart from the semi – monocoque rear fuselage, the covering of the whole airframe was fabric. The prototype had a Bristol Jupiter, in a helmeted cowling, while the first production batch had the same 480hp engine built under licence as the M-22 and cowled in a Townend ring. The second batch, from Kharkov, had the 700hp M-25 (Wright Cyclone). The main landing gears variously had spatted wheels, plain wheels or skis. The guns were suspended from both main spars outboard of the struts (just in­board on the first prototype), and were fed at a slow rate from a seven-round magazine in the wing. A PV-1 machine gun was fitted to right of centre ahead of the windscreen to as­sist aiming using the optical sight. The tailplane was mounted high to avoid the rear blast from the APK-4s.

This neat aircraft did all that was expected of it, but none of Kurchevskii’s big guns ever became operational.

Purpose: To investigate the use of pulsejets to boost fighter performance.

Design Bureau: The OKB of Semyon A Lavochkin.

In 1942 Vladimir N Chelomey, working at TsIAM (Central Institute of Aviation Motors) began bench-testing the first pulsejet in the Soviet Union. This was independent of work by the German Argus company, which be­cause of Soviet secrecy became famed as the pioneer of such engines. The Soviet unit re­ceived two designations, D-10 and RD-13. In 1946 the first two flight-cleared D-10 engines were hung under the wings of a slightly mod­ified La-7, which was designated La-7PVRD. In the second half of 1947 a second pair, des­ignated RD-13, were flown under the wings of an La-9, which misleadingly received the des­ignation La-9RD. Despite the fact that the pro­gramme had already been abandoned, eight further La-9 fighters were fitted with these en­gines, and all nine made a deafening forma­tion flypast at the Tushino Aviation Day.

Left: La-7/2D-10.

The D-10 pulsejet appears to have been heavier than the German 109-014 unit of sim­ilar size, though weight data are lacking. The duct was mainly aluminium at the front and steel to the rear ofthe fuel injectors. Fuel was drawn from the main aircraft tanks and igni­tion was electrical. The unit was suspended from a shallow pylon projecting ahead of the wing leading edge with two main attach­ments, with a steadying attachment at the rear. Apart from the pulsejet instrumentation and control system a few modifications were needed to the aircraft, the main one being to remove a large portion of flap above the pulsejet jetpipe. No data are available de­scribing how thrust varied with airspeed or height; Shavrov merely gives the thrust of a single D-10 as 200kg (44 lib).

Though these pulsejets performed as ex­pected, they significantly added to aircraft weight and drag, and reduced manoeuvrabil­ity, especially rate of roll. In addition, the vio­lent vibration transmitted to the aircraft ‘made flying difficult’ and was very unpopular with pilots.

By the late 1950s the Mikoyan OKB had moved on to envisage this as the ultimate sin­gle-engined heavy interceptor. It was to have the R-15B-300 engine, with a maximum rating of 10,210kg (22,509 Ib) and an improved propulsive nozzle of convergent/divergent form, considerably greater internal fuel ca­pacity in an added fuselage spine, wingtip rails for the Volkov K-80 missile (later pro­duced as the R-4R and R-4T), and many other modifications including canard foreplanes which this time were to be fully powered. The Ye-152/2 was rebuilt into the Ye-152P (from Perekhvatchik, interceptor) as a stepping stone to the Ye-152M. Externally it incorporat­ed all the new features, including the roots for the foreplanes, but the surfaces themselves were not fitted. By the time the rebuild was complete the IA-PVO (manned fighter branch of the air defence forces) had selected the Tupolev Tu-128, and Mikoyan was well ahead with the far more impressive twin-engined MiG-25. In 1965 the Ye-152P, with the missile launchers replaced by more pointed wing – tips, was put on display as the ‘Ye-166’, adorned with the details of the records set by the Ye-152/1. It still survives at the Monino museum in Moscow.

Top left: I-3U.

Top right: I-7U.

Above and right: Two views of I-75. Bottom: Ye-150.

Photographs on the opposite page:

Top left: e-l52A.

Top right: Ye-152A with K-9-155 mis siles.

Centre: Ye-152A with K-9-155 missiles.

Bottom: Ye-152/1 with K-9-155 missiles.

Photographs on this page:

Above: Ye-152M project model.

Top left, centre and bottom right: Ye-152M with K-80 missile mock-ups.

Top right: Ye-152M record version (so-called ’Ye-166′) at Monino.

Ye-2, Ye-4, Ye-5

The Korean War of 1950-53 triggered a signifi­cant acceleration of development of weapons in the Soviet Union. For the first time the ‘MiG’ OKB found itself working under intense pres­sure on two distinct classes offighter. The first to be launched were the big radar-equipped interceptors typified by a wing area of 30m2 (323ft2) and engines in the thrust range 9,072 to 13,608kg (20,000 to 30,000 Ib). The second family were small but agile fighters intended for close visual combat, characterised by wings of some 22m2 (237ft2) and engines in the 5,000kg (ll,0201b) class. The smaller air­craft were required to reach Mach 2 on the level at heights up to 20km (65,617ft) whilst carrying guns and a radar-ranging sight. Inten­sive tunnel testing failed to show clear superi­ority between a swept wing rather like a small version of that of the MiG-19, with a leading – edge sweep of 61°, and the new delta (trian­gular) shape with a leading-edge angle of 57°, so it was decided to build experimental ver­sions of both. The single engine was Tuman – skii’s AM-9B (later called RD-9B), as used in the twin-engined MiG-19, with a maximum af­terburning thrust of3,250kg (7,165 Ib). The fol­lowing specification refers to the swept-wing Ye-2, first flown on 14th February 1955. This led to the mixed-power Ye-50. The Ye-4, the first of the deltas, was very similar but had a disappointing performance. Despite this, with minor changes the delta Ye-5 was some 700km/h faster, leading to the production MiG-21. Even though all versions had limited capability, this small fighter was produced in four countries in greater numbers than any other military aircraft since 1945 apart from the MiG-15. Assuming 2,400 for Chinese pro­duction the total was 13,409.

Ye-50

Right at the start of the ‘Ye’ programme Mikoyan had planned a mixed-power proto­type, the Ye-lA, with the afterburning turbojet boosted by a Dushkin S-155 rocket engine. This was never built, but in 1954 it was re­stored to the programme with the designa­tion Ye-50. One reason was the British Saro SR.53, with a similar propulsion system, and another was that the definitive RD-11 (later called R-l 1) engine was still some two years off. An order was received for three Ye-50 air­craft, and Ye-50/1 made its first flight (without using the rocket) on 9th January 1956, the same day as the first Ye-5. Though similar in size to the Ye-2 already described, the empty weight of the Ye-50/1 was 4,401kg (9,702 Ib). This was because of the rocket engine and its tanks, an extended nose and additional equipment. The main engine was an RD-9Ye rated at 3,800kg (8,377 Ib). The S-155 was fed with RFNA (red fuming nitric acid) and kerosene by a turbopump in the swollen base of the fin, driven by decomposing high-test hydrogen peroxide. The thrust chamber was immediately to the rear, above the main-en­gine afterburner. The whole rocket installa­tion, though complex, was refined and reliable. On the turbojet alone this heavy air­craft was underpowered, and the bulk of the rocket and its tankage meant that with re­duced jet fuel the range was very short. This aircraft was damaged beyond repair on its 18th fiight on 14th July 1956. The Ye-50/2 reached 2,460km/h (l,529mph, Mach 2.32). The Ye-50/3 incorporated various modifica­tions, but suffered inflight catastrophe, killing Nil pilot N A Korovin. Gor’kiy received a con­tract for a single Ye-50A with greatly in­creased rocket and jet fuel, made possible by a large tank scabbed on under the fuselage, but the Ministry decided against mixed – power aircraft (preferring much more power­ful main engines) and the Ye-50A was never completed.

Ye-6/3T

The MJG-21F, the first series version, went into production at Gor’kiy in 1959. The facto­ry designation was Ye-6/3T, and the third pro­duction aircraft, the 3T, was set aside to explore the effect of fitting canard (nose) foreplanes. These were small delta-shaped surfaces with cropped tips, the leading-edge angle being 45°. They were not powered but were pivoted on axes skewed at 40° and free
to align themselves with the local airflow. To prevent flutter a lead-filled rod projected ahead of the leading edge at mid-span. Their purpose was merely to reduce longitudinal static stability, but they were considered to be ineffectual in use.

Purpose: Flying-wing transport or bomber. Design Bureau: OOS, Russian for Section for Experimental Aeroplane Construction, Moscow Tushino.

Along with Kozlov (see ‘invisible aircraft’ story) the chief designer at OOS was Alek­sandr Ivanovich Putilov, who joined from CAHI (TsAGI) when OOS was just a group in­
terested in steel airframes. The Stal’ (steel) 5 was sketched in 1933 in two forms, as a trans­port and also as the KhB (Khimicheskii Boye – vik), an attack aircraft for spraying poison gas (obviously it could also carry bombs). In 1934 a complete wing spar was made for static test, and in late 1935 VVKarpov and Ya G Paul actually flight-tested a scale model with a span of 6m (19ft 7in), wing area of
15.0m2 (161.5ft2) and two 45hp Salmson en­gines. It was difficult to fly, and the idea was dropped.

Putilov’s flying wing was to be powered by two 750hp M-34F water-cooled V-12 engines. The structure was to have been almost en­tirely Enerzh-6 stainless steel, skinned with Bakelite-bonded veneer over the centre sec­tion and fabric elsewhere. The drawing shows the slotted flaps, elevator and four re­tractable wheels. The payload was to have been between the spars in the centroplan (centre wing), deep enough for people to walk upright.

Several designers, notably the American Burnelli, tried to make extra-efficient aircraft along these lines. None succeeded.

Dimensions

Span 23.0m 75 ft 5Л in

Length 12.5m 41ft

Wing area 120nf l,292ft!

Weights (estimated)

Empty 5.5 tonnes 12,125 Ib

Loaded 8 tonnes 17,640 Ib

No other data.

Purpose: To create a Mach-3 strategic weapons system.

Design Bureau: P O Sukhoi, Moscow, with major subcontract to TMZ, Tushino Machine-Building Factory.

This enormous project was triggered in Dec­ember 1962 by the need to intercept the B-70 (or RS-70), ‘A-ll’ (A-12, later SR-71), Hound Dog and Blue Steel. At an early stage the mis­sion was changed to strategic reconnais­sance and strike for use against major surface targets. It was also suggested that the basic air vehicle could form the starting point for the design of an advanced SST. From the outset there were bitter arguments. Initially these centred on whether the requirement should be met by a Mach-2 aluminium aircraft or whether the design speed should be Mach 3, requiring steel and/or titanium. In January
1963 Mach 3 was selected, together with a de­sign range at high altitude on internal fuel of 6,000km (3,728 miles). General Constructors Sukhoi, Tupolev and Yakovlev competed, with the T-4, Tu-135 and Yak-33 respectively. The Yak was too small (in the TSR.2 class) and did not meet the requirements, and though it looked like the B-70 the Tupolev was an aluminium aircraft designed for Mach 2.35. From the start Sukhoi had gone for Mach 3, and its uncompromising design resulted in its being chosen in April 1963. This was despite the implacable opposition not only of Tupolev but also of Sukhoi’s own deputy Yevgenii Ivanov and many of the OKB’s department heads, who all thought this de­manding project an unwarranted departure from tactical fighters. Over the next 18 months their opposition thwarted a plan for the for­mer Lavochkin OKB and factory to assist the

T-4, and in its place the Boorevestnik (stormy petrel) OKB and the TMZ factory were ap­pointed as Sukhoi branch offices, the Tushino plant handling all prototype construction. A special WS commission studied the project from 23rd May to 3rd June 1963, and a further commission studied the refined design in February-May 1964. By this time the T-4 was the biggest tunnel-test project at CAHI (TsAGI) and by far the largest at the Central In­stitute of Aviation Motors. The design was studied by GKAT (State aircraft technical committee) from June 1964, and approved by it in October of that year. By this time it had outgrown its four Tumanskii R-15BF-300 or Zubets RD-17-15 engines and was based on four Kolesov RD-36-41 engines. In January 1965 it was decided to instal these all close to­gether as in the B-70, instead of in two pairs. Mockup review took place from 17th January

to 2nd February 1966, with various detach­able weapons and avionics pods being of­fered. Preliminary design was completed in June 1966, and because its take-off weight was expected to be 100 tonnes the Factory designation 100 was chosen, with nickname Sotka (one hundred). The first flight article was designated 101, and the static-test speci­men 100S. The planned programme then in­cluded the 102 (with a modified structure with more composites and no brittle alloys) for testing the nav/attack system, the 103 and 104 for live bomb and missile tests and deter­mination of the range, the 105 for avionics in­tegration and the 106 for clearance of the whole strike/reconnaissance system. On 30th December 1971 the first article, Black 101, was transferred from Tushino to the LII Zhukovskii test airfield. On 20th April 1972 it was accepted by the flight-test crew, Vladimir Ilyushin and navigator Nikolai Alfyorov, and made its first flight on 22nd August 1972. The gear was left extended on Flights 1 through 5, after which speed was gradually built up to Mach 1.28 on Flight 9 on 8th August 1973. There were no serious problems, though the aft fuselage tank needed a steel heat shield and there were minor difficulties with the hy­draulics. The WS request for 1970-75 includ­ed 250 T-4 bombers, for which tooling was being put in place at the world’s largest aircraft factory, at Kazan. After much further argument, duringwhich Minister P V Demen – t’yev told Marshal Grechko he could have his enormous MiG-23 order only if the T-4 was abandoned, the programme was cancelled. Black 101 flew once more, on 22nd January 1974, to log a total of lOhrs 20min. Most of the second aircraft, article 102, which had been about to fly, went to the Moscow Aviation In­stitute, and Nos 103-106 were scrapped. Back in 1967 the Sukhoi OKB had begun working on a totally redesigned and significantly more advanced successor, the T-4MS, or 200. Ter­mination ofthe T-4 resulted in this even more remarkable project also being abandoned. In 1982 Aircraft 101 went to the Monino muse­um. The Kazan plant instead produced the Tu-22MandTu-160.

In all essentials the T-4 was a clone on a smaller scale of the North American B-70. The structure was made of high-strength tita­nium alloys VT-20, VT-21L and VT-22, stain­less steels VIS-2 and VIS-5, structural steel VKS-210 and, for fuel and hydraulic piping, soldered VNS-2 steel. The wing, with 0° an – hedral, had an inboard leading-edge angle of 75° 44′, changed over most of the span to 60° 17′. Thickness/chord ratio was a remark-

able 2.7 per cent. The leading edge was fixed. The flight controls were driven by irreversible power units in a quadruplex FBW (fly-by­wire) system with full authority but automat­ic manual reversion following failure of any two channels. They comprised four elevens on each wing, flapped canard foreplanes and a two-part rudder. The fuselage had a circular diameter of 2.0m (6ft 6%in). At airspeeds below 700km/h (435mph) the nose could be drooped 12° 12′ by a screwjack driven by hy­draulic motors to give the pilot a view ahead. Behind the pilot (Ilyushin succeeded in get­ting the proposed control wheel replaced by a stick) was the navigator and systems man­ager. Both crew had a K-36 ejection-seat, fired up through the normal entrance hatch, and aircraft 101 also had a pilot periscope. Be­hind the pressure cabin was a large refriger­ated fuselage section devoted to electronics. Next came the three fuel tanks, filled with 57 tonnes (125,661 Ib) of specially developed RG-1 naphthyl fuel similar to JP-7. Each tank had a hydraulically driven turbopump, and the fuel system was largely automated. A pro­duction T-4 would have had provision for a large drop tank under each wing, and for air refuelling. Behind the aft tank were systems compartments, ending with a rectangular tube housing quadruple cruciform braking parachutes. Under the wing was the enor­
mous box housing the air-inlet systems and the four single-shaft RD-36-41 turbojets, each with an afterburning rating of 16,000kg (35,273 Ib). An automatic FBW system gov­erned the engines and their three-section variable nozzles and variable-geometry in­lets. Each main landing gear had four twin- tyred wheels and retracted forwards, rotating 90° to lie on its side outboard of the engine duct. The nose gear had levered suspension to two similar tyres, with wheel brakes, and used the hydraulic steering as a shimmy damper. It retracted backwards into a bay between the engine ducts. The four auto­nomous hydraulic systems were filled with KhS-1 (similar to Oronite 70) and operated at the exceptional pressure of 280kg/cm2 (3,980 lb/in2). A liquid oxygen system was pro­vided, together with high-capacity environ­mental systems which rejected heat to both air and fuel. The crew wore pressure suits. The main electrical system was generated as 400-Hz three-phase at 220/115 V by four oil – cooled alternators rated at 60 kVA. Aircraft 101 never received its full astro-inertial navi­gation system, nor its planned ‘complex’ of electronic-warfare, reconnaissance and weapon systems. The latter would have in­cluded two Kh-45 cruise missiles, developed by the Sukhoi OKB, with a range of 1,500km (932 miles).

Like the B-70 this was a gigantic pro­gramme which broke much new ground (the OKB said ‘200 inventions, or600 ifyou include manufacturing processes’) yet which was fi­nally judged to have been not worth the cost.

Purpose: To test wing forms for the 100 aircraft.

Design Bureau: P O Sukhoi, Moscow.

Another of the aircraft used to provide re­search support for the 100, or T-4, was this modified Su-9 interceptor. In the period 1966­70 this aircraft was fitted with a succession of different wings. Most testing was done at LII Zhukovskii.

The 100L was originally a test Su-9, with side number (callsign) Red 61 (the same as for the T6-1, and also for the first two-seat MiG-21, but this had finished testing at LII be­fore the 100L arrived). The aircraft was fitted with telemetry with a diagonal blade antenna under the nose, but apparently not with a cine camera at the top of the fin. The various test wings were manufactured by adding to the existing Su-9 wing box, in most cases ahead of the wing box only. The first experimental wing was little changed in plan view: the wing was given an extended sharp leading edge which extended the tip to a point. Three fur­ther wings with sharp leading edges were
tested, as well as one with a ‘blunt leading edge’. This meant that it was the sharply swept inboard leading edge that was blunt, because at least one of the wings was fitted with a leading edge which in four stages in­creased in sweepback from tip to root to meet the fuselage at 75°. All the test wings had perforated leading edges from which smoke trails could be emitted. Further testing was done with a sharp-edged horizontal tail.

Results from this aircraft were aerodynam­ic, not structural, but they materially assisted the design ofthe 100.

Purpose: To create fighters and interceptors with new and untried features.

Design Bureau: OKB-115 ofA S Yakovlev, Moscow.

Yakovlev was one of the two General Con­structors who created the first jet aircraft in the Soviet Union (the other was Mikoyan). Yakovlev cheated by, in effect, putting a tur­bojet into a Yak-3 ! A succession of single-en­gined jet fighters followed, one ofwhich was the Yak-25 of 1947 (confusingly, Yakovlev later used the same designation for a different aircraft, see later). This achieved the excel­lent speed of 972km/h (604mph) on the 1,588kg (3,500 Ib) thrust of a single Rolls- Royce Derwent engine (thus, it was faster than a Gloster Meteor on half as many Der­went engines). The first of two Yak-25 proto­types was modified to evaluate an idea proposed by the DA (Dal’nyaya Aviatsiya, long-range aviation). Called Burlaki (barge – hauler) this scheme was to arrange for a strategic bomber to tow a jet fighter on the end of a cable until it was deep in enemy air­space and likely to encounter hostile fighters. The friendly fighter pilot would then start his engine and cast off, ready for combat. The first of the two Yak-25 prototypes was ac­cordingly fitted with a long tube projecting ahead of the nose, with a special connector on the end. The two aircraft would take off in­dependently. The bomber would unreel a cable with a special connector on the end, into which the fighter would thrust its probe, as in probe/drogue flight refuelling. It would thus have a free ride to the target area. The idea was eventually rejected: towing the fighter reduced the range of the bomber, the fighter might not have enough range to get home (unless by chance it could find a friend­ly bomber and hook on), the long tube affect­ed the fighter’s agility and, worst of all, the fighter pilot would have to engage the enemy after several hours sitting in a freezing cockpit with no pressurization.

One of the least-known Soviet aircraft was the Yak-1000. The late Jean Alexander was the only Western writer to suggest that this extraordinary creation might have been in­tended purely for research, and even she re­peated the universal belief that its engine was a Lyul’ka AL-5. In fact, instead ofthat impres­sive axial engine of5,000kg (11,023 Ib) thrust, the strangely numbered Yak-1000 had a Rolls- Royce Derwent of less than one-third as muchthrust. Designed in 1948-49, this aircraft was notable for having a wing and horizontal

Centre: Yak-1000.

Bottom: Yak-25E Burlaki.

tail of startlingly short span (wing span was a mere 4.52m, 14ft l0in), almost of delta form and with a thickness/chord ratio nowhere greater than 4.5 per cent and only 3.4 per cent at the wing root. Behind the rear spar the en­tire wing comprised a powerful slotted flap, the outer portion ofwhich incorporated a rec­tangular aileron. The tailplane was fixed half­way up the fin, which again was a low – aspect-ratio delta fitted with a small rudder at the top. The long tube-like fuselage had the air inlet in the nose, the air duct being imme­diately bifurcated to pass either side of the cockpit, which was pressurized and had an ejection-seat. The inevitably limited supply of 597 litres (131 Imperial gallons) of fuel was housed in one tank ahead of the engine and another round the jetpipe. The only way to arrange the landing gear was to have a nose – wheel and single (not twin, as commonly thought) mainwheel on the centreline and small stabilizing wheels under the wings. Flight controls were manual, the flaps, land­ing gear and other services were worked pneumatically, and the structure was light alloy except for the central wing spar which was high-tensile SOKhGSNA steel. Only one flight article was built, the objective being a speed in level flight of 1,750km/h (1,087mph, Mach 1.65). Taxi testing began in 1951, and as soon as high speeds were reached the Yak-1000 exhibited such dangerous instabili­ty that no attempt was made to fly it.

In the jet era there is no doubt that Yakovlev’s most important aircraft were the incredibly varied families of tactical twin-jets with basic designations from Yak-25 (the sec­ond time this designation was used) to Yak-28. Some of the sub-variants were exper­imental in nature. One was the Yak-27V, V al­most certainly standing for Vysotnyi, high altitude, because it was specifically intended for high-altitude interceptions. This was a sin­gle flight article, which had originally been constructed as the Yak-121, the prototype for the Yak-27 family, with callsign Red 55. To turn it into the Yak-27V it was converted into a single-seater, and a Dushkin S-155 rocket engine was installed in the rear fuselage, re­placing the braking parachute. The S-155 had a complicated propellant supply and control system, because it combined petrol (gaso­line) fuel with a mixture of RFNA (red fuming nitric acid) and HTP (high-test hydrogen per­oxide) oxidant, plus a nitrogen purging sys­tem to avoid explosions. Brochure thrust of the S-155 was 1,300kg (2,866 Ib) at sea level, rising to 1,550kg (3,417 Ib) at 12km (39,370ft). Airframe modifications included adding an extended and drooped outer leading edge to the wing (though the chordwise extension
was not as large as in the later Yak-28 family), converting the horizontal tail into one-piece stabiliators, fitting the rearranged tankage, and replacing the nose radar by a metal nose. The two NR-30 cannon were retained. The RD-9AK engines were replaced by the spe­cially developed RD-9AKE, with a combustion chamber and fuel system specially tailored for high altitudes; thrust was unchanged at 2,800kg (6,173 lb). Yakovlev hired VGMukhin to join the OKB’s large test-pilot team be­cause he had tested the mixed-power Mikoy – an Ye-50 with a similar S-155 rocket engine. He opened the test-flying programme on 26th April 1956. Service ceiling of the Yak-27V was found to be 23.5km (77,100ft), and level speed above 14km (45,900ft) about 1,913km/h (l,189mph, Machl.8).

Yakovlev had been fortunate in having members of this prolific twin-jet family in se­ries production at four large factories, No 99 at Ulan-Ude, No 125 at Irkutsk, No 153 at Novosi­birsk and No 292 at Saratov. Unfortunately, by 1964 no new orders were being placed and the end was in sight. In that year, right at the end of the development of the family, Yakovlev tried to prolong its life by undertak­ing a major redesign. He sent his son Sergei to study the variable inlets and engine installa­tion of the rival Su-15, and he also carefully studied the MiG Ye-155, the prototypes for the MiG-25. All these were faster than any Yaks, and they had engines in the fuselage. Ac­cordingly, whilst keeping as many parts un­changed as possible, the Yak-28-64 was created, and this single flight article, callsign Red 64, began flight testing in 1966. The en­gines remained the R-l 1AF2-300, as used in most Yak-28s (and also, as the R-l 1F2-300, in many MiG-21s), with dry and afterburning ratings of 3,950kg (8,708 Ib) and 6,120kg (13,492 Ib) respectively. Instead ofbeing hung under the wings they were close together in the rear fuselage, fed by vertical two-dimen­sional inlets with variable profile and area. Drop tanks could be hung under the inlet ducts on the flanks of the broad fuselage. This wide fuselage added almost a metre to the span (from 11.64m, 38ft 2%in, to 12.5m, 41ft), and removing the engines from the wings en­abled the ailerons to be extended inboard to meet the flaps. Armament comprised four guided missiles, two from the K-8 family (typ­ically an R-8M and an R-8T) and two R-3S copies of the American Sidewinder. To Yakovlev’s enormous disappointment, the huge sum spent by the OKB in developing this aircraft was wasted. Its performance was if anything inferior to that of the Yak-28P, and handling was unsatisfactory to the point of being unacceptable.

Top: Yak-36 c/n 38, with rocket pods.

Two views of Yak-36 experimental VTOL aircraft.

In 1960 Yakovlev watched the Short SC. l cavorting at Farnborough and became capti­vated by the concept of SWP (Russian for VTOL, vertical take-off and landing). Though he received funding for various impressive Yak-33 studies in which batteries of lift jets would have been installed in a supersonic at­tack aircraft, he quickly decided to build a simple test-bed in the class of the Hawker P.1127, with vectored nozzles. No turbofan existed which could readily be fitted with four nozzles, as in the British aircraft, but, after funding was provided by the MAP and the propulsion institute CIAM, K Khachaturov in the Tumanskii engine bureau developed the R-27 fighter turbojet into the R-27V-300 with a nozzle able to be vectored through a total angle of 100°. Rated initially at 6,350kg (14,0001b), this engine had a diameter of 1,060mm (3ft 5%in) and so it was a practical proposition to fit two close side-by-side in a small fuselage. Of course, the engines had to be handed, because the rotating final nozzle had to be on the outboard side. This was the basis for the Yak-36 research aircraft, intend­ed to explore what could be done to perfect the handling of a jet-lift aeroplane able to hover. To minimise weight, the rest of the air­craft was kept as small as possible. The en­gines were installed in the bottom of the fuselage with nozzles at the centre of gravity, fed directly by nose inlets. The single-seat cockpit, with side-hinged canopy and later fit­ted with a seat which was arranged to eject automatically in any life-threatening situa­tion, was directly above the engines. The small wing, tapered on the leading edge and with -5° anhedral, was fitted with slotted flaps and powered ailerons. Behind the engines the fuselage quickly tapered to a tailcone, and carried a vertical tail swept sharply back to place the swept horizontal tail, mounted
near the top, as far back as possible. The tailplane was fixed, and the elevators and rudder were fully powered. For control at low airspeeds air bled from the engines was blast­ed through downward-pointing reaction-con­trol nozzles on the wingtips and under the tailcone and on the tip of a long tubular boom projecting ahead of the nose. The nose and tail jets had twin inclined nozzles which were controllable individually to give authority in yaw as well as in pitch. The landing gear was a simple four-point arrangement, with wingtip stabilizing wheels, of the kind seen on many earlier Yak aircraft. The OKB factory built a static-test airframe and three flight ar­ticles, Numbered 36, 37 and 38. Tunnel test­ing at C AHI (TsAGI) began in autumn 1962, LII pilot Yu A Garnayev made the first outdoor tethered flight on 9th January 1963 and Valentin Mukhin began free hovering on 27th September 1964. On 7th February 1966 No 38 took off vertically, accelerated to wingborne flight and then made a fast landing with noz­zles at 0°. On 24th March 1966 a complete transition was accomplished, with a VTO fol­lowed by a high-speed pass followed by a VL. The LII stated that maximum speed was about l,000km/h, while the OKB claimed U00km/h (683mph). Both Nos 37 and 38 were flown to Domodedovo for Aviation Day on 9th July 1967. Later brief trials were flown from the helicopter cruiser Moskva.

From the Yak-3 6 were derived the Yak-36M, Yak-38, Yak-38U and Yak-38M, all of which saw service with the A-VMF (Soviet naval avi­ation). This inspired the OKB to produce the obvious next-generation aircraft, with fully su­personic performance. A design contract was received in 1975. Yak called the project Izdeliye (Product) 48, and it received the Ser­vice designation Yak-41. Seldom had there been so many possible aircraft configura-

tions, but at least this time funds were made available for the necessary main engine. With much help from CIAM, this was created as the R-79V-300 by the Soyuz bureau, led after Tu – manskii’s death in 1973 by Oleg N Favorskii, and from 1987 by Vasili K Kobchenko. The R-79 was a two-shaft turbofan with a bypass ratio of 1.0, with a neat augmentor and a fully variable final nozzle joined by three wedge rings which, when rotated, could vector the nozzle through 63° for STO (short take-off) or through 95° for VTO (vertical take-off). Rat­ings were 11,000kg (24,250 Ib) dry, 15,500kg (34,171 Ib) with maximum augmentation and 14,000kg (30,864 Ib) with maximum augmen­tation combined with maximum airbleed for aircraft control. The reason the nozzle vec­tored through 95° was because, immediately behind the cockpit, the Yak-41 had two Ry­binsk (Novikov) RD-41 lift jets in tandem whose mean inclination was 85°. Their noz­zles had limited vectoring but, at this mean position, in hovering flight they blasted down and back so the main engine had to balance the longitudinal component by blasting down and forwards. Sea-level thrust of each RD-41 was 4,100kg (9,040Ib); thus, total jet lift was about22,200kg (48,942 Ib), but in fact the Yak – 41 was not designed to fly at anything like this weight. Compared with its predecessors it was far more sharp-edged and angular. The wing had a thickness/chord ratio of 4.0 per cent, and leading-edge taper of 40°. The outer wings, which in fact had slight sweepback on the trailing edge, folded for stowage on air­craft carriers. The leading edge had a large curved root extension, outboard of which was a powerful droop flap. On the trailing edge were plain flaps and powered ailerons. The wing had -4° anhedral, and was mount­ed on top of a wide box-like mid-fuselage, from which projected a slim nose and cock-

pit ahead of the large variable wedge inlets which led to ducts which, behind the lift engines, curved together to feed the main en­gine. The latter’s nozzle was as far forward as possible. Beside it on each side was a narrow but deep beam carrying a powered tailplane and a slightly outward-sloping fin with a small rudder. Unlike most military Yak jets the Yak-41 had a conventional tricycle landing gear. In hovering flight recirculation was min­imised by the open lift-bay doors, a hinged transverse dam across the fuselage ahead of the main gears, a large almost square door hydraulically forced down ahead of the main engine nozzle, and a long horizontal strake along the sharp bottom edge of the fuselage on each side. Fuselage tanks held 5,500 litres (1,210 Imperial gallons) of fuel, and a 2,000 litre (440 Imperial gallon) conformal tank could be scabbed under the fuselage. Flight and engine controls were eventually inter­linked and digital, the hovering controls com­prising twin tandem jets at the wingtips and a laterally swivelling nozzle under the nose (which replaced yaw valves at the tip of each tailcone). An interlinked system provided automatic firing of the K-36LV seat in any dan­gerous flight situation. In 1985 it was recog­nized that such a complex and costly aircraft ought to have multi-role capability, and the new designation Yak-41 M was issued for an aircraft with extremely comprehensive avion­ics and weapons. Equipment included a 30mm gun and up to 2.6 tonnes (5,732 Ib) of ordnance on four underwing pylons. The OKB received funding for a static/fatigue test aircraft called 48-0, a powerplant test-bed (48-1) and two flight articles, 48-2 (callsign 75) and 48-3 (callsign 77). Andrei A Sinitsyn flew ’75’ as a conventional aircraft at Zhu – kovskii on 9th March 1987. He first hovered ’77’ on 29th December 1989, and in this air­craft he made the first complete transition on 13th June 1990. Maximum speed was 1,850km/h (1,150mph, Mach 1.74) and rate of climb 15km (49,213ft) per minute. In April 1991 Sinitsyn set 12 FAI class records for rapid climb with various loads, and as the true des­ignation was classified the FAI were told the aircraft was the ‘Yak-141’. In September 1992 48-2 was flown to the Farnborough airshow, its side number 75 being replaced by ‘141’. A year earlier the CIS Navy had terminated the whole Yak-41 M programme, and the appear­ance in the West was a fruitless last attempt to find a partner to continue the world’s only programme at that time for a supersonic jet – lift aircraft. Apart from publicity, all today’s Yakovlev Corporation finally received for all this work was a limited contract to assist Lockheed Martin’s Joint Strike Fighter.

Opposite: Yak-41 M with Yak-38M.

This page, top: Yak-141, No 75 on carrier.