Category Soviet x-plenes

Design Bureau: In most cases, the OKB-155 ofAI Mikoyan.

Made possible by Britain’s export of Rolls – Royce Nene turbojets to Moscow in Septem­ber 1946, the Aircraft S marked a dramatic leap forward in Soviet fighter design. First flown on 30th December 1947, it was far ahead of any other fighter in Europe. In 1949 it went into large-scale production as the MiG – 15. In the Korean war (1950-53) it completely outperformed Allied aircraft (the F-86 was the only rival in the same class) and put the name ‘MiG’ in the limelight around the world, where it remains to this day. A total of 11,073 of all versions were constructed in the USSR, and the global total exceeded 16,085 (the Chi­nese output is not known precisely). Many have served in experimental programmes. These, and other MiG types, require treat­ment that is not apposite in the context of this book. What follows therefore is the specifica­tion for a typical standard late production ver­sion, the MiG-15b/s, incorporating numerous aerodynamic, control, systems and engine improvements overthe original MiG-15. Much more detail of experimental MiG-15s will be included in an Aerofax on the MiG-15 which will be published in 2001. The engine of the MiG-15b/s was the VK-1, derived from the Nene and rated at 2,700kg (5,952 Ib).

su

One of the experimental versions of the basic (not £>/s) aircraft was given the OKB designa­tion SU. Originally a standard fighter, MiG-15 No 109035, with callsign 935 painted on the fuselage, it was used to test the V-I-25/Sh-3. This was the designation for a fighter arma­ment system developed by the Shpital’nyi weapons bureau. The standard quick-change armament pack housing one 37mm and two 23mm guns was replaced by a fixed installa­tion of two powerful Sh-3 23mm guns, each
with 115 rounds. Each gun was mounted below the fuselage in a streamlined fairing. The barrel projected through a vertical slot so that, mounted on trunnions and driven by an irreversible electric screwjack, it could be el­evated to +11° and depressed to -7° (there was no lateral movement). The Ministry order for this conversion was signed on 14th Sep­tember 1950, and the SU was factory-tested between 2nd January and 27th March 1951. NIl-WS testing followed from 30th June to 10th August 1951. The general opinion was that in tight turning combat the system was useful in bringing the guns to bear, and it also enabled a head-on attack to be made with less risk of collision. The NIl-WS report called for a better sight, and for the guns to pivot over a greater angular range.

SYe

Written SE in Cyrillic characters, this was a tangible result of years of research into the endemic problem of poor or even reversed lateral control, wing drop and inadequate yaw (directional) control, especially at high Mach numbers. Most of the research was done at CAHI (TsAGI), but two workers at LIl-MAP (the Ministry flight research insti-

tute), I M Pashkovskii and D I Mazurskii, also took a hand. After various tests they made recommendations to AI Mikoyan, who or­dered the OKB to construct two SYe aircraft, based on the MiG-156/s. An obvious modifi­cation was that the fin leading edge was kinked to maintain a, broad chord to the top. Among other changes the wings were stiff­ened and fitted with ailerons of higher aspect ratio ending in square tips. The first SYe, call­sign 510, was assigned to LIl-MAP pilot D M Tyuterev, who dived it to Mach 0.985 despite having unboosted ailerons. The ailerons were then fitted with BU-1 boosters, whereupon on 18th October 1949 Tyuterev dived it to beyond Mach 1, the first MiG aircraft to achieve this.

Burlaki

One ofthe deeper problems of the Soviet ADD (Strategic Aviation) was how to escort the Tu-4. No fighter, especially a jet, had anything like adequate range. Aircraft designer A S Yakovlev suggested making the bombers tow fighters to the target area (see Yak-25E). Mikoyan briefly worked on a similar Burlaki (barge-hauler) scheme, fitting a MiG-155/s with a harpoon clamp above the nose which the pilot could hook on a crossbar on the end ofa long cable reeled out from the Tu-4. Ifhos- tile fighters were encountered the MiG pilot would start the engine, release the tow and en­gage combat. In theory he could then hook on
again for the ride home. It was not considered a viable idea, one reason being that with the engine inoperative the MiG pilot had no cock­pit pressurization and also became frozen.

Refuelling test-beds

An alternative to the Burlaki method was Dozapravka v Vozdukhe, refuelling in flight. Extensive trials took place in 1949-53 using
various MiG-15 s and Tu-4 tankers. Eventually a system was used almost identical to that de­vised by the British Flight Refuelling Ltd, with hoses trailed from the tanker’s wingtips and a probe on the nose of the fighter. Apart from the basic piloting difficulty, problems includ­ed probe breakage, pumping of bulk fuel into the fighter’s engine and the need for an im­proved beacon homing method for finding the tanker at night or in bad weather.

Purpose: T o build a more efficient light transport.

Design Bureau: NIAI, initials from Scientific Research Aero Institute, Leningrad, formed by the LIIPS, the Leningrad Institute for Aerial Communication; designers AI Lisichkin and V F Rentel.

Even though it went into production and everyday use, this aircraft qualifies by virtue of

its extraordinary layout, with the wing blend­ed into the fuselage. The prototype, with civil registration LI 300, was first flown by A Ya Ivanov in May 1933. Despite the fact that the pilot had no view except over a sector of about 100° to the left side, Ivanov’s opinion was favourable because the aircraft handled well. After four months of testing in Leningrad the LK-1 was flown to Moscow. There it was tested by the Nil, as a result of which a small
series of 20 were built. These saw Aeroflot service in the Arctic, on occasion being fitted with skis or floats.

LK stood for Leningradskii Kombinat, and the prototype was also unofficially called Fan – era-2 (Plywood 2). Though basically a simple all-wood machine, powered by a l00hp M-l 1 engine, it strove to gain in lift/drag ratio by blending the wing root into the fuselage. In­deed, it could be considered as an all-wing

LK-1 senesaircraft

aircraft with the nose engine and rear fuse­lage attached to the thickened centre wing. This central portion contained two pairs of seats, that on the left in front being for the pilot. The entire front and top of this cabin was skinned in transparent panels, those along the sides sloping at 60°, two of them forming doors. The prototype had a ring – cowled engine, spatted main wheels and a broad but squat fin and rudder. Production aircraft had no cowling or spats, but had a re­designed wing root and a narrower rear fuse­lage and completely redesigned vertical tail.

Several designers attempted a cabin of this kind, but all the others were very large air-

Purpose: To create a supersonic radar – equipped interceptor.

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

After closure of his OKB, in December 1949 Sukhoi became deputy to his old colleague A N Tupolev, where among other things he collaborated with CAHI (TsAGI) in establish­ing the best wing for supersonic fighters. He played the central role in deciding on two contrasting forms. For tactical fighters the choice was an S (Strelovidnoye, arrow like) swept wing with a!4-chord sweep angle of 60° or 62°, and for radar-equipped interceptors the best answer was a T (Treoogol’noye, three-angled, ie delta) wing with J4-chord sweep angle of 57° or 60°. For obvious rea­sons, the latter type of wing was soon dubbed Balalaika. On Stalin’s death Sukhoi applied for permission to reopen his OKB. This was at once granted, and in May 1953 he gathered his team at the original premises at 23A Po – likarpov Street. Following from his aerody­namic research he received MAP contracts for basically similar aircraft, S-l with the S wing and T-l with the T wing. As he chose to build large aircraft powered by a powerful Lyul’ka engine, which matured rapidly, their development was swift. S-l led to the pro­duction Su-7 and many other aircraft. T-l was replaced on the drawing board by T-3, and
this was flown by V N Makhalin on 26th May 1956. Just over a month later it was the final aircraft in the parade of new fighters at Tushi – no on 24th June, causing intense interest and great confusion in the West. A few weeks be­hind came the PT-7. These were tested inten­sively by a pilot team which included Pronyarkin, Koznov, Kobishkan and the fu­ture Sukhoi chief test pilot Vladimir Ilyushin, son of the General Designer.

Like S-l, the T-3 had a barrel-like fuselage, much of its length being occupied by the big afterburning AL-7F engine, rated at 9,000kg (19,840 Ib) with afterburner and 6,500kg (14,330 Ib) dry. The tails of the two aircraft were almost identical, and there were only minor differences in the cockpit, landing gear and most of the systems. The wings of both aircraft were in the low/mid position, at­tached by precision bolts to strong forged root ribs on heavy forged fuselage frames. The wing had S-9s profile with a thickness/chord ratio of4.2 per cent over most of the span. The shape was almost a perfect delta, with a lead­ing-edge angle of 60°. The leading edge was fixed, while the trailing edge comprised rec­tangular slotted flaps with a maximum angle of 25° and sharply tapered ailerons with inset hinges which extended to the near-pointed tips. Incidence was 0° and dihedral -2° (ie, 2° anhedral). Structurally the wing had three main spars, each principally a machined forg­
ing, plus a rear spar to carry the trailing-edge surfaces. The leading edge was attached to the front of a further spar forming the front of the structural box. The forward triangle ahead of Spar 1 and the volume between Spars 2 and 3 were sealed and formed inte­gral fuel tanks. The whole space between Spars 1 and 2 was occupied by the retracted main landing gear. The flaps were driven at their inboard ends by electro-hydraulic power units inside fairings under the lower wing surface. The circular-section fuselage was liberally covered with access doors and hatches. The nose was just one of several contrasting answers tested by Sukhoi to the problem of fitting radar into a supersonic fighter. The fire-control system was to be one of the Uragan (Hurricane) family, with the search scanner at the top of the nose and the Almaz (Diamond) ranging radar underneath inside the inlet. The main scanner was inside a low-drag radome in the form of a flattened cone (with a curious upward tilt) from which projected the PVD-7 instrumentation boom combining the pitot/static heads with pitch and yaw vanes. Additional instrument booms were mounted inboard of each wingtip. Even though the T-3 was to be a supersonic aircraft there seemed no alternative to making the radome over the ranging set a bluff hemi­sphere, which had an adverse effect on pres­sure recovery in the air inlet. The latter
immediately divided into left and right ducts which quickly expanded into vertically sym­metric ducts along each fuselage wall. These combined behind the cockpit into a circular tube passing above the wing and then ex­panding to fill virtually the entire fuselage cross-section to mate with the face of the en­gine compressor at Frame 29. Between Frames 31 and 32 on each side of the top of
the fuselage was a large grilled aperture through which hot air could be violently ex­pelled from the compressor during engine start. At Frame 32 a bolted joint enabled the entire rear fuselage to be removed for servic­ing or changing the engine. At Frame 38 were hinged four door-type airbrakes with large slot perforations. At Frame 43 were the skewed pivots for the horizontal tailplanes, each of which was a single-piece ‘slab’ with a leading-edge sweep of 60° and an anti-flutter mass projecting forwards near each tip. The large fin curved away from a dorsal extension
in which a screwed panel gave access to the power unit driving the rudder, which was hung on three inset hinges. Each tail sur­face had chem-milled skins attached to ribs at 90° to the surface rear spar. The fuselage tail end was mainly of titanium. The nose landing gear had a 660 x 200 tyre and retract­ed forwards. Each main unit had an 880 x 230 tyre and, unlike the swept-wing Sukhois, re­tracted straight inwards. Track was 4.65m (15ft Sin) and wheelbase 5.05m (16ft 7in). The cockpit housed an ejection-seat and had a bulletproof windscreen and one-piece

frameless canopy sliding to the rear. Among the comprehensive avionics suite were two items with antennas in the top of the fin, the slots for the Svod (Arch) navaid and SOD-57 transponder and the RSIU-5V inside the di­electric fin cap. The wings were plumbed for drop tanks, to be carried on pylons only just in­board of the instrument booms. The planned armament was two guns (Sukhoi assumed the NR-30), and steel blast panels were pro­
vided in the sides of the forward fuselage. Be­fore the T-3 was completed the guns were re­placed by missiles. The intended weapon was the K-6, to be carried on interfaces attached where the tanks would have been.

The PT-7 differed mainly in having an area – ruled fuselage, with a visibly waisted middle section, and a new ranging radar with a point­ed downward-inclined radome projecting from the bottom ofthe nose. Other differences
included unperforated airbrakes and a revised fin-cap antenna which extended around the top of the slightly shortened rudder.

These aircraft were the first in what proved to be a long succession of prototype and ex­perimental aircraft in the search for the best interceptor. This underscored the Soviet Union’s determination to accept nothing but the best, because any of these aircraft could have been accepted for production.

Dimensions (T-3) Span 8.7 m 28ft6!fln Length (inc instrument boom) 18.82 m 61 ft m in Wing area (net) 24.9 m! 268.8ft2 Weights Empty 7,490kg 16,512 Ib Loaded (normal) 9,060 kg 19,974 Ib Maximum 11,200kg 24,691 Ib Performance Maximum speed at 10 km (32,808 ft) 2,100 km/h 1,305 mph (Mach 1.98) Service ceiling 18km 59,055 ft Range (internal fuel) 1,440km 895 miles (maximum) 1,840km 1,143 miles Take-off and landing runs, both about 1,100m 3,600 ft

Top: The T-3 at the 1956 Tushino Fly Past. Bottom: PT-7 inlet.

Purpose: To use Tu-2 aircraft for various experimental purposes.

Design Bureau: Originally, CCB-29 (or TsKB-29) and GAZ (Factory) No 156.

Created during A N Tupolev’s period in de­tention under a ludicrously false ‘show trial’ charge, the Tu-2 (previously ‘Aircraft 103’, but really the 58th ‘ANT’ design), was an out­standing multirole tactical bomber. Its ridicu­lous gestation, with its creator working on a drawing board in a locked cell, meant that it did not enter service until May 1942, but de­spite this some 3,300 were delivered from Factories 156, 166 and 125. As soon as spare examples became available they were snapped up for use as test-beds. The very first series aircraft, No 100716, was used to test the ASh-83 engine, rated at l,900hp, driving four-blade AV-5V propellers (replacing the standard 1,850hp ASh-82FN driving the three – blade AV-5V-167 or four-blade square-tip AV-9VF-21K). Maximum speed of this test­bed was 635km/h (395mph) at 7,100m (23,294ft).

Numerous test versions appeared in 1944, including the first two of three Shturmovik (armoured ground attack) versions with spe­cial armament, all proposed by Tupolev’s ar­mament brigade leader A D Nadashkevich. The first, actually given the designation Tu-2Sh, had its capacious weapon bay occu­pied by a specially designed aluminium box housing 88 modified PPSh-41 infantry ma­
chine carbines (sub-machine guns). These fired standard 7.62mm pistol ammunition, and all fired together pointing obliquely down at a 30° angle. The obvious shortcoming was that, even though the drum magazines held 71 rounds, they were quickly emptied.

The second 1944 Sh version had a massive 75mm gun under the fuselage, reloaded by the navigator. Two more ground-attack ver­sions appeared in 1946. The first had the dev­astating forward-facing armament of two 20mm ShVAK, two NS-37 and two NS-45. The 37mm gun was 267mm (101/2in) long and weighed 150kg (33lib). The 45mm version had a shorter barrel but still fired its 1.065kg (2.35 Ib) projectiles at 850m (2,790ft) per sec­ond, and weighed 152kg (335 Ib).

The last of these variants was the two-seat RShR, or Tu-2RShR. This was a dedicated anti-armour aircraft, carrying a high-velocity 57mm RShR automatic cannon with the bar­rel projecting ahead of the metal-skinned nose and fitted with a prominent recoil brake.

The most startling modification was the Tu-2 Paravan (paravane). Two of these were built, to test a crude way of surviving impact with barrage-balloon cables. A special cable woven from high-tensile steel was run from one wingtip to the other via the end of a monocoque cone projecting over 6m (20ft) ahead of the nose. The nose and wingtips were reinforced. First flown in September 1944, this lash-up still reached 537km/h (334mph) despite the strange installation and
a 150kg (331 Ib) balancing weight in the tail. These trials were not considered to have been successful.

Yet another 1944 modification was the Tu-2K (Katapult), fitted with test ejection – seats. The first Tu-2K fitted the test seat in the navigator’s cockpit just behind the pilot. A second ejection-seat tester had the experi­mental seat mounted in an open cockpit at what had been the radio operator’s station in the rear fuselage.

In early 1945 the Type 104 radar-intercep­tion system began flight testing (the first to be airborne in the Soviet Union). The system had been designed from 1943, by a team led by A L Mints, and the Type 104 test aircraft had begun flighttesting on 18th July 1944 but with the vital radar simulated by ballast. The pilot had a modified sight, which was later linked to the radar, and fired two VYa-23 cannon in­stalled under the forward fuselage. The rear fuselage was faired over and contained noth­ing but a balancing mass.

The designation Tupolev Tu-2G was ap­plied to several Gruzovoi (cargo) conver­sions. It appears that all of these were experimental, carrying special loads either in the remarkably large bomb bay or slung ex­ternally, and in many cases the load was dropped by parachute. No fewer than 49 GAZ – 67b armoured reconnaissance cars were dropped, the Tu-2G in this case being limited to a height of 6km (19,685ft) and a speed of 378km/h (235mph).

As explained in the stories of the Pe-2 and Pe-8 experimental versions, the German Fi 103 (‘V. 1’) flying bomb was the basis for a large Soviet programme of air-launched cruise missiles in the immediate post-war era. One ofthe later variants was the 16Kh Pri – boi (surf, breaking waves). The fact this was fitted with twin engines meant that it could be carried under the Tu-2. The first modified Tu-2 launch aircraft began testing at LII on 28th January 1948, and live missile launchings took place on the Akhtuba range between 22nd July and 25th December 1948, testing the D-312 and D-14-4 engines and various electric or pneumatic flight-control systems. The Tu-2 launch aircraft continued in the
process of refining guidance and improving reliability until at least 4th November 1950, by which time the Tu-4 was being modified as carrier aircraft with one missile under each outer nacelle. The WS rejected the 16Kh on grounds of poor accuracy, and eventually the argument reached Stalin who shortly before his death terminated this missile.

Experimental Tu-2 aircraft were also used to develop air-refuelling.

Not least, in the immediate post-war era the Tu-2 was the most important aircraft con­verted to air-test turbojet engines. Occasion­ally the designation Tu-2LL (flying laboratory) was used, but one of the most important was (possibly unofficially) designated Tu-2N,
because it was allocated to test the imported Rolls-Royce Nene. This required the test engine to be mounted in a nacelle of large diameter (basic engine diameter 1.26m, 4ft 11/2in). Later more than one Tu-2 was used to test Soviet RD-45 and VK-1 derivatives of the Nene, including variants with an afterburner. However, these were all preceded by aircraft, some of which had been Tupolev Type 61 prototypes, which were converted to test cap­tured German axial engines: the BMW 003A (Soviet designation RD-20) and the Junkers Jumo 004B (Soviet designation RD-10). An­other 61 prototype was used to test the first Soviet turbojet to fly, the Lyul’kaTR-1, in 1946.

Purpose: Experimental fighter.

Design Bureau: V N Belyayev, working at GAZ (factory) No 156, Moscow.

This EOI (Eksperimental’nyi Odnomestnyi Istrebitel’, experimental single-seat fighter) was proposed in early 1939, and personally approved by Stalin in August of that year. De­sign and manufacture proceeded through 1940, and at the German invasion of 22nd June 1941 the first flight was only a few months away.

In October the Moscow factories were evacuated. It was decided to abandon the project, and the part-complete EOI, drawings and calculations were destroyed. When pho­tographs of the FBI (see above) were discov­ered it was at first thought that this must be the same aircraft. In fact, there was little sim­ilarity between the two designs apart from the basic configuration.

The EOI had the cockpit in the nose, almost perfectly streamlined, with armament in the same location. Possibly for the first time in history, Belyayev designed the entire front section of the aircraft to be separated in emergency, so that the pilot would not have to bail out ahead of the propeller. The latter was to be driven by a Klimov M-105 engine, rated at l,100hp and fitted with a TK-2 tur­bocharger. In the original scheme, like fight­ers of 1917 by Gallaudet in the USA and Dufaux in France, the propeller was to have a large-diameter hub through which passed a tube carrying the rear fuselage. Some of the ‘370’ drawings are reproduced overleaf. One shows the proposed cockpit, armament of two underfloor VYa-23 cannon and location of the cartridge-severed attachments. Anoth­er drawing shows the unique arrangement in which the wing was to be provided with a slat. This auxiliary surface was normally
housed in a recess immediately ahead of the flap or aileron. For take-off and landing it was to be swung down and forward to adopt a leading-edge-down attitude ahead of the leading edge of the wing. Thus, it was a bold­er precursor of today’s Krueger flap. Whether or not this aerodynamically powerful idea was abandoned is unknown, but Belyayev certainly abandoned the original rear fuse­lage. By late 1939 he had decided to use con­ventional twin tail booms. The specification overleaf applies to this revised scheme.

According to one document it was intend­ed that a production version should have had the M-106 engine. This would have been rated at 1,350hp, instead of 1,100hp. Whether the unconventional configuration, and espe­cially the potentially dangerous slat system, would have shown to advantage will never be known.

Sketch drawings of 370

11.4m 37 ft 5 in 19 nf 205ft2 700km/h 435 mph

On take-off and landing

Model of the final EOI configuration.

Purpose: Ultra-fast attack bomber.

Design Bureau: WIA (air force engineering academy) located at the Zhukovskii Academy, Moscow, where Viktor Fedorovich Bolkhovitinov was Professor of Aircraft Design and head of design team.

The objective was to make the fastest bomber in the world, by using a fighter-type layout with two powerful engines in tandem. This arrangement was adopted in order to achieve engine-out safety with minimum drag. Design of the propulsion system began in 1936 and of the aircraft itself a year later. The designation stood for Sparka (Twin), but other designations were S 2M-103 (in usual Soviet style, showing the engines), BBS-1 (short-range bomber, fast, the S here mean­ing Skorostnii, speedy) and LB-S (light bomber, twin). Construction of the single pro­totype began in July 1938, the first flight was made by B N Kudrin in late 1939, and NIl-WS testing took place between March and July 1940, the pilots being Kudrin and AIKa – banov. It was found that take-off run was ex­cessive. In 1940-41 the aircraft was subjected to major modifications. ZI Itskovich re­designed the wing with increased area and a changed aerofoil profile. A different front en­
gine was fitted, and the rear engine and its propeller were replaced by an inert mass. The oil coolers were incorporated in the main radiator duct. As the redesigned aircraft neared completion snow was still on the ground, and the landing gears were all re­placed by fixed skis.

No way was found to make proper use of the bay previously occupied by the rear en­gine, and in any case performance was now unimpressive. After the German invasion work was abandoned. Plans for an improved S bomber and a derived I (or I-1) fighter with two M-107 engines were also dropped.

The airframe was entirely a modern light – alloy stressed-skin structure. The wing was based on a structural box with two plate spars with flanged lightening holes, sheet ribs and heavy upper and lower skins with flush rivet­ing. The fuselage basically comprised top, bottom and side panels all joined to four strong angle-section longerons (Shavrov: ‘later this construction was used for the IL-28’, a post-war jet bomber). The twin-finned tail had thin Dl skin throughout, the rudders hav­ing inset balanced hinges, the tailplanes being pivoted and driven by irreversible trim­ming motors and the elevators having trim tabs and a variable geared drive. Each main
landing gear retracted electrically back­wards, the wheel turning through 90°.

The 960hp M-103 engines (V-12 liquid – cooled derived from the Hispano-Suiza 12Y) were mounted in tandem, the rear engine dri­ving the rear unit of the contra-rotating six – blade propeller. Some reports state that the drive was taken via left/right twin shafts past the front engine’s crankcase, but in fact (as in the Italian Macchi M. C.72 racing seaplane of 1933) the rear engine drove a single shaft be­tween the front-engine cylinder blocks which finally passed through the centre of the front – engine propeller shaft. Both engines were served by a large ducted radiator with a con­trollable exit flap (this was positioned by one of the 29 on-board electric actuators) and two oil coolers were fitted in ducts on each side of the front engine. Four fuel tanks were housed between the wing spars, and on the trailing edge were electrically driven slotted flaps (in several reports, incorrectly called Fowler

type).

Pilot and navigator sat in tandem, far apart under a long Plexiglas canopy. The navigator also had a bomb sight, and the entire area around his seat was skinned in Plexiglas. Turning to the rear he could fire a 7.62mm ShKAS, and it was the intention later to re-

place this by twin 12.7mm UBT. Behind the rear spar, under the pilot’s cockpit, was a bay housing 400kg (882 Ib) of bombs, with two electrically driven doors. It was the intention later to fit fixed guns in the wings.

The second wing, of NACA-230 profile, gave improved field length. One report states that a remotely controlled ShKAS was added in the extreme tail, but this does not appear in any known photographs. Continued poten­tially dangerous problems with the rear en­gine and its drive resulted in this being removed. The front engine was changed to an M-l 05P, ofunchanged 960hp, driving a sin­gle three-blade propeller. Even with weight considerably reduced the S was then judged a failure, though tandem-engine studies con­tinued. The factory was tooled up for Pe-2 production.

Though an article by Ing V Mikhailov and Ing VPerov states that, following initial Nil testing ‘the design team was instructed to continue development’, there is no doubt the S was always on the verge of success but never getting there. The high wing loading and the failure to solve the rear-engine drive problem made it one of the programmes abandoned after the invasion of June 1941.

Purpose: Simple jet (rocket + ramjet) fighter.

Design Bureau: RNII (reaction-engine scientific research institute) and OKB No 55.

By 1940 the idea ofthe PVRD (ramjet) was fa­miliar in the Soviet Union, mainly to boost the speed of piston-engined fighters. In 1940 Pro­fessor Mikhail Tikhonravov, on the RNII staff, had the better idea of making a simpler and lighter fighter with a ZhRD (liquid-propellant rocket) in the tail and PVRDs under the wings. This could put together various thing s already developed in the Soviet Union to create what might have been a cheap and quickly pro­duced fighter which, apart from short range and endurance, would have had outstanding performance. Unfortunately, perhaps be­cause it appeared unconventional, this pro­ject suffered from endless argument and foot-dragging, finally falling victim to a deci­sion to abandon all such aircraft. According to Shavrov, ‘The proposal did not attract any ob­jections from A G Kostikov, Director of the RNII. It was continued as a preliminary pro­ject, and approved by the Technical Council of the RNII in spring 1941. It was later exam­ined by a commission of specialists at the WA’ (air force academy). This commission, comprising S A Christianovich, A V Chesalov, S N Shishkin, V I Polikovskii and others, pro­claimed that This project does not bring out anything new’. Work proceeded at a snail’s pace, and Kostikov then took the proposal to the NKAP (state commissariat for aviation in­dustry), where Tikhonravov defended it on 17-18th July 1942. In No vember 1942 Ko stiko v showed the proposal to K E Voroshilov, and eventually Stalin himself gave authority for work to resume, appointing Kostikov chief designer. From this time onwards many doc­uments called the project ‘Ko-3’. Funding was
provided for two prototypes, and to build these the RNII set up OKB-55, appointing as director M R Bisnovat (see earlier) and A A Andreyev as his deputy. Tikhonravov did the aerodynamic calculations, while stress­ing was in the hands of V D Yarovitskii. By spring 1943 two 302 aircraft were almost completed. Testing in the T-104 tunnel at CAHI (TsAGI) began at this time. In 1943 the original proposed ramjets were changed to a new design by Vladimir Stepanovich Zuyev. These were initially tested in a half-scale form, but full-scale testing was never carried out. After much argument it was decided to forget the ramjets and complete the aircraft as the 302P (Perekhvatchik, interceptor) with the rocket only. The PVRD attachments under the wings were faired over, and the wing span reduced. This was flight-tested as a glider at the LII from August 1943, towed to altitude by a North American B-25 and Tu-2. The as­signed pilot was initially S N Anokhin, fol­lowed by M L Gallai and B N Kudrin, with V N Yelagin as test engineer. The 302P was found to be ‘exceptionally good, stable and pleasant to fly’, and in March 1944 the second 302P was being tested in the T-104 tunnel at CAHI. In the same month the whole pro­gramme was cancelled. A recent Russian magazine article about the 302 omits any mention ofTikhonravov.

The 302 was made mainly of wood, with a monocoque fuselage and smooth skin of

Delta and Shpon veneers bonded by Bakelite – type plastics. The wings had 15-per-cent RAF.34 profile at the root, tapering to 8-per­cent NACA-230 near the pointed tip. In con­trast, the control surfaces were of Dl alloy with fabric covering, the starboard aileron, rudder and both elevators having trim tabs. The rocket engine was a Dushkin/Shtokolov D-1A with a main chamber rated at 1,100kg (2,4251b) at sea level and a cruise chamber rated at 450kg (992 Ib). Under the wings were to have been installed the ramjets, but infor­mation on these Zuyev units is lacking. Their nacelles were to have been oval, with the major axis horizontal, faired neatly into the wing. The all-rocket 302P had tanks for 1,230kg (2,712 Ib) of RFNA (concentrated ni­tric acid) and 505kg (1,113 Ib) of kerosene. The cockpit, which was to have been pres­surized, had a canopy hinged to the right and a bulletproof windscreen and frontal armour. The main and tailwheel landing gears were to have been retracted hydraulically, and the same system would have operated the split flaps. No documents have been found de­scribing how the environmental and hy­draulic systems would have been energised. Two 20mm ShVAK cannon were to have been mounted in the nose and two more in the bottom of the forward fuselage, each with 100 rounds. In addition, there was to have been provision for underwing racks for RS-82 or RS-132 rockets or two FAB-125 bombs.

With the benefit of hindsight this appears to 302P in CAHI (TsAGl) wind tunnel. have been a considerable case of ‘might have been’. Kostikov was a political animal who saw in Tikhonravov’s proposal a means to gain advancement and power. Instead, in 1944 a commission headed by A S Yakovlev found him responsible for the failure of the 302 to develop on schedule; he was dis­missed from his post and later imprisoned.

302P

Design Bureau: OKB-155 ofAI Mikoyan.

Throughout 1949 the MiG OKB was busy cre­ating the SI, the prototype of a MiG-15 deriva­tive incorporating numerous improvements. Most of these were aerodynamic, including a completely redesigned wing, a horizontal tail of increased sweep on an extended rear fuse­lage, and improved flight controls. The first flight article, SI-2, was flown on 13th January 1950, and on 1st September 1951 MAP Order No 851 required the SI to be put into produc­tion as the MiG-17. Because of the sheer mo­mentum of MiG-15 production the improved aircraft did not replace it in the factories until October 1952. The following specification refers to the MJG-17F, by far the most impor­tant version, which was powered by the af­terburning VK-1F, with a maximum rating of 3,380kg (7,451 Ib).

SN

In late 1953 the MiG Factory 155 produced an experimental fighter representing the next stage beyond the SU. This time the entire for­ward fuselage was redesigned to house the pivoted guns, the engine being fed by lateral inlets and ducts passing both above and below the wing torsion box (which was given front and rear fairings). Ahead of Frame 13 the entire nose was occupied by the SV-25 ar­mament installation devised by the TKB (Tula design bureau) of Afanas’yev and Makarov. This was based on a large frame mounted on needle-roller bearings on each side and piv­oted on a transverse axis over the range +27° 267-9° 28′ (not 9° 48′ as previously pub­lished). On this frame were mounted three TKB-495 lightweight 23mm guns, fed by box magazines mounted on the fixed structure. The whole installation weighed 469kg (l,0341b), requiring a balancing increase in the size of Tank 3 in the rear fuselage. As this

aircraft was so non-standard anyway the OKB took the opportunity to try a few other changes. Of course a special gunsight was needed, and it may have been to improve the optics that a new windscreen was designed, wider and longer than before and giving a bet­ter field of view ahead. The SN was factory – tested by Georgiy K Mosolov from mid-1953. It proved a failure, with seriously reduced flight performance and useless armament. Because the guns were so far ahead of the centre of gravity and centre of pressure of the aircraft, firing them at large angles from the horizontal caused powerfulpitchingmoments which threw the aim off-target. Mikoyan de­cided the problem was not readily soluble. Numerous otherwise unmodified MiG-17s were also used as armament test-beds.

SI-10

This MiG-17 was one of the original type with the non-afterburning VK-1A engine, with call­sign 214. Having studied the wing and tail of the F-86E Sabre, this aircraft was fitted with important aerodynamic and control changes. The wing was fitted with large automatic slats over the outer 76 per cent of each leading edge, large area-increasing (Fowler-type) flaps, and spoilers (called interceptors) under the outer wings which opened whenever the adjacent aileron was deflected more than 6°. In addition, a fully powered irreversible tailplane was fitted, with limits of +37-5°, re­taining the elevators driven by a linkage to add camber. Grigorii A Sedov flew No 214 on 27th November 1954, followed by many other OKB and NIl-WS pilots. Opinions were favourable, especially regarding the horizon­tal tail, but it was not worth disrupting MiG-17 production to incorporate the changes.

Purpose: To evaluate an aeroplane with a wing of variable area.

Design Bureau: NIAI, Leningrad.

In 1936 Grigorii (according to Shavrov, Georgii) Ivanovich Bakshayev, aged 18, joined the UK GVF, the instructional combine of the civil air fleet. He was eager to test his belief that a su­perior aeroplane could be created by arrang­ing for it to have a large wing for take-off and landing and a smaller wing for cruise. As the UK GVF was in Leningrad the NIAI adopted the idea. Called RK (Razdvizhnoye Krylo, ex­tending wing), and also LIG-7 because it was the seventh project of the Leningrad Institute GVF, the aircraft was built quickly and was first flown in August 1937. Remarkably, the
system worked smoothly and reliably (better in the air than on the ground), and it led to the evenmore unconventional RK-I fighter.

Apart from the wing the RK was a simple monoplane of mixed construction, with en­closed cockpits for a pilot and observer and powered by an uncowled l00hp M-l 1 engine driving a laminated-wood propeller. It had a two-spar wing of constant narrow-chord M-6 profile, braced by pairs of wires above and below to the top of the pilot’s hood and to a pyramid truss under the fuselage. At the root was what looked like the root section of a much larger wing, with CAHI (TsAGI)-846 aerofoil profile, but with a span of only 50cm (1ft 7%in). Inside this, nestling tightly like a set of Russian Matroshka dolls, were five further
plywood wing sections each of 50cm span. The observer could crank these out by a cable mechanism, each adding 45cm (1ft 5%in) to the span of the large-chord region. It took 30 to 40 seconds to crank the telescopic sections out to their full extent, covering 60 per cent of the semi-span, and 25 to 30 seconds to wind them back.

Seemingly a ‘crackpot’ idea, the RK per­formed even better than prediction. It is diffi­cult to account for the fact that it got nowhere. The answer must be that it introduced an el­ement of complexity and possible serious danger, sufficient to dissuade any later de­signer from following suit.

Purpose: To create a fighter with variable wing area.

Design Bureau: NIAI, Leningrad.

From the start of his telescopic-wing studies young Bakshayev had really been thinking about fighters. He had regarded the RK mere­ly as a preliminary proof-of-concept exercise. He calculated that a fighter able to retract most of its wing area and powered by the M – 105 engine ought to be able to reach a world – record 800km/h (497mph), overlooking the fact that a fighter with a relatively small wing would have poor combat manoeuvrability. Indeed, as described below, he found a way to make the relative difference between the small and large wings even greater than in the RK, the ratio of areas being 2.35:1. In October 1938 he submitted a preliminary design sketch for the RK-I (Russian abbreviation for extending-wing fighter). After much argu­ment the concept was accepted by CAHI (TsAGI) and the WS. A one-fifth-scale model was tested in a CAHI (TsAGI) tunnel from Jan­uary 1939, but it was difficult to find an indus­trial base capable of building even the prototype. Worse, the RK-I attracted the at­tention of Stalin, who took a keen interest in combat aircraft. Excited, he demanded that this aircraft should use the M-106 engine, the most powerful then on bench test. Under
some difficulty a prototype RK-I was com­pleted in early 1940, but the M-106 engine (later designated VK-106) was still far from ready. The aircraft could have flown with the M-105, but nobody dared to fit anything but the engine decreed by Stalin. In order to do at least some testing a full-scale model was con­structed with the nose faired off, fixed landing gears and a projecting canopy, with no at­tempt to simulate armament or the radiator ducts in the rear fuselage. This mock-up was then tested in the CAHI (TsAGI) full-scale tun­nel. The resulting test report was generally favourable, but noted that sealing between the telescopic wing sections was inadequate. The CAHI (TsAGI) aerodynamicists neverthe­less concluded that with the M-106 the speed might be 780km/h (485mph). Lacking an en­gine the project came to a halt, and after the German invasion in June 1941 it was aban­doned. Bakshayev was appointed to super­vise increased production of the 156km/h (97mph) U-2 (Po-2) at Factory No 387.

The lifting surfaces of the RK-I were unique, and quite unlike anything attempted by any other designer. The aircraft was all-metal, the large fuselage being a light-alloy monocoque which would have housed the 1,800hp M-106 in the nose with the oil cooler underneath and surrounded by two 20mm ShVAK can­non and two 7.62mm ShKAS machine guns.

Behind the firewall were successively the fuel tanks, backwards-retracting single-strut main landing gears, enclosed cockpit and the gly­col coolant radiator with controllable air ducts on each side of the rear fuselage. The amazing feature was that there were two wings of equal span and narrow tapering chord, one in front of the cockpit and the sec­ond, set at a slightly lower level, behind. Each had upper and lower skins of spot-welded SOKhGSA stainless steel, and the rear wing was fitted with three hinged trailing-edge sur­faces on each side serving as flaps and ailerons. These movable surfaces, like the tail, were made of light alloy. The unique fea­ture was that on this aircraft the root of the large wing extended completely around the front wing and back almost to mid-chord of the rear wing. Nested inside it were 14 further wing profiles, which in 14 seconds could be winched out over the entire span by an elec­tric motor and cable track along the rear wing leading edge, which was at right angles to the longitudinal axis. Each section of the large wing comprised a Dural leading edge and rib with a fabric skin, the first section sealing the side of the fuselage in the high-speed condi­tion and serving as a wing end-plate in the ex­tended low-speed configuration. Shavrov gives the weight of all 28 telescopic sections as approximately 330kg (727.5 Ib). Changing

Purpose: To create a further-improved interceptor.

Design Bureau: OKB-51 ofP O Sukhoi, Moscow.

In May 1958 the OKB-51 decided that, after more than four years of effort, they had still not found the best answer to the problem of how to arrange the radar, air inlet(s) and ar­mament of a single-engined supersonic inter­ceptor. It was recognized that guided missiles would be carried externally, probably under the wings, leaving the nose free for radar, but the engine inlet still posed a problem. The PT-8 and T-47 had large radars centred in a nose inlet, and this was considered to de­grade the aerodynamics. Accordingly a new arrangement was devised, and the OKB con­veniently were able to graft it on to the in­complete T-39 (T-3 derivative). The result
thus received the designation T-49. By June 1958 work on the T-39 had been stopped, and this project was transferred as a test-bed to the Central Institute of Aviation Motors. Conversion to the T-49 was completed by Oc­tober 1958. In 1959 M Goncharov was ap­pointed to supervise flight testing, but the T-49 remained on the ground – much of the time being used for various tests – until in January 1960 it was flown by Anatoly Koznov. He re­ported outstanding acceleration and good all­round performance, but by this time aircraft in this class had been overtaken by later tech­nology. In April 1960 the T-49 was damaged in an inflight accident, and though it was re­paired it never flew again.

The T-49 was by virtue of its ancestry very similar to the simpler versions of T-4 family aircraft such as the production Su-9. Like that aircraft it was intended to be armed with two
guided missiles carried on pylons under the outer wings, but these would have been of the K-8 type as carried by the Su-11. The large fixed radome was uncompromised by the in­lets, which were located well back on each side. In side elevation each inlet was vertical, seen from the front it formed a 90° segment curved round the side of the fuselage, and in plan it was swept back at 60°. To match pres­sure recovery over the whole range of flight Mach numbers the inner wall was made vari­able in angle and throat area. The intention was to make the whole inlet system isentrop – ic (causing no change in entropy) to achieve maximum compression of the airflow. Like several other Sukhoi designs of the period there were two vertical doors in each side of the fuselage at Frame 7 to spill excess air from the ducts. The engine was a Lyul’ka AL-7F-100, with a dry rating of 6,900kg (15,212 Ib) and maximum afterburning thrust of 9,900kg (21,82515). This was achieved without the need for the injection of water, the T-39’s rear-fuselage water tank being re­placed by one for fuel. Other features includ­ed steel doubler plates left over from the T-39 near where gun muzzles would have been had they been fitted, tailplanes fitted with anti-flutter masses and driven over the ex­ceptional angular range +97-16°, and flaps whose trailing-edge roots were cut away at 45°, which was also a feature of the pro­duction Su-11.

This promising aircraft was overtaken by galloping technology.