Category Soviet x-plenes

Purpose: To investigate high-altitude flight, and if possible set records.

Design Bureau: The Byuro Osobykh Konstruktsii, the Bureau of Special Design, Smolensk. BOK was formed in 1930 in Moscow as a subsidiary of CAHI (TsAGI) to build experimental aircraft ordered by the Revolutionary Military Council. Despite starting on existing projects it made slow progress, and in September 1931 was transferred to the CCB (TsKB) as Brigade No 6. It had undergone other transformations, and been relocated at Smolensk, by the time work began on BOK – 1. Director and Chief Designer was Vladimir Antonovich Chizhevskii.

One of the bureau’s first assignments was to create an aircraft to explore flight at extreme altitudes, seen as ‘Nol priority’. Close links between the USSR and Junkers resulted in BOK sending a team to Dessau in 1932 to
study the Ju 49, and in particular its pressur­ized cabin. This strongly influenced their thinking, and led to many studies for a Soviet counterpart, but the only hardware built was the balloon SSSR-1, with a pressur­ized gondola, which in 1933 exceeded 18km (59,055ft). In 1934 a major conference of the Academy of Sciences issued a programme for future research, one requirement being a high-altitude aircraft. The contract for the SS (Stratosfernyi Samolyot, stratospheric aero­plane) was signed with BOK.

By this time Tupolev had designed the long – range RD (ANT-25), and to save time BOK used this as the basis for the BOK-1. The main task was to design the pressure cabin, but there were many other major modifications. The BOK-1 was built at GAZ (State Aircraft Factory) No 35 at Smolensk, where it was first flown by I F Petrov in (it is believed, in Sep­tember) 1936. It was repeatedly modified in order to climb higher. It was successfully put
throughGOSNIl-GVF State testing by PM Ste – fanovskii. Shavrov speaks of’ a lighter variant’ achieving greater heights, but there is no evi­dence of a second BOK-1 having been built.

The airframe was originally that of one of the military RD aircraft, but modified by GAZ No 35. The span was reduced by fitting new constant-taper outer panels, restressed for significantly reduced gross weight achieved by greatly reducing the fuel capaci­ty. The massive retractable twin-wheel main landing gears were replaced by lighter fixed units with spatted single wheels. The engine was an AM-34RN liquid-cooled V-12, rated at 725hp, driving a three-blade fixed-pitch propeller.

The main new feature was the pressure cabin, seating the pilot and a backseater who acted as observer, navigator and radio opera­tor (though no radio was ever installed). This cabin was a sealed drum of oval cross-sec­tion, with closely spaced frames to bear the

bursting stress, constructed of Dl light alloy with 1.8 or 2.0mm skin riveted over a sealing compound. Design dP (pressure differential) was 0.22kg/cm2 (3.2 lb/in2). The front and rear were sealed by convex bulkheads. The entry hatch was at the rear and an escape hatch was provided in the roof. One report says there was no room for parachutes, which were stowed in the rear fuselage. There were five small glazed portholes for the pilot and one on each side ahead of the backseater. There were also four small portholes to admit light to the unpressurized rear fuselage. A re­generative system circulated the cabin air and removed carbon dioxide (one report says ‘and nitrogen’). A controlled leak through a dump valve was made good by oxygen from bottles to keep oxygen content approximate­ly constant. The engine cooling circuit heated a radiator covering the cabin floor to keep in­ternal temperature at 15-18°C.

Flight testing revealed satisfactory flying characteristics and a lack of vibration. On the other hand, on any prolonged flight the cabin became uncomfortably hot. Despite this, and electric heating of the portholes, the glazed surfaces quickly misted over. In any case, ex­ternal vision was judged dangerously inade­quate.

Shavrov states that the cabin was qualified for flight to ‘8,000m and more’; this is am­biguous, and the original design objective was that the interior should be equivalent to an altitude of 8,000m (26,250ft) at the design ceiling of the aircraft. The engine cooling cir­cuit was modified, and the portholes were re­placed by double-layer sandwiches with not only electric heating but also a dessicant (moisture absorber) between the panes. This overcame the condensation, but nothing could be done to improve field of view.

In spring 1937 the BOK-1 was fitted with an 830hp M-34RNV engine, driving a four-blade fixed-pitch propeller. This engine was then fit­ted with two TK-1 turbosuperchargers, de­signed by VI Dmitriyevskiy so that the combined turbo exhausts also added a thrust of 70kg (1541b). With the new engine instal­lation the altitude performance was much improved (see data), but during an attempt to set a record for height reached with 500 and 1,000kg payload one of the turbos blew up. Shavrov says merely ‘the attempt failed’, but another account says the exploding turbo se­riously damaged the forward fuselage and re­sulted in the BOK-1 being scrapped.

The BOK-1 was only the second aeroplane in the world to be designed with a pressure cabin. It achieved most of its objectives, but failed to set any records.

Top: BOK-1 pressure cabin. Centre: BOK-1 inboard profile. Bottom: BOK-1 (final form).

Purpose: To create a super-heavy bomber. Design Bureau: OKB ofK A Kalinin,

Kharkov.

From 1925 Kalinin made himselffamous with a series of single-engined aircraft charac­terised by having a quasi-elliptical mono­plane wing. In 1930 he sketched a gigantic transport aircraft, the K-7, with a tail carried on two booms and with four 1,000hp engines mounted on the wing, which was deep enough to house 60 passengers or 20 tonnes of cargo. No engine of this power was readily available, so in 1931 he redesigned the air­craft to have seven engines of (he hoped) 830hp. GUAP (the Ministry of Aviation Indus­try) gave permission for the aircraft to be built, but with the role changed to a heavy bomber. This meant a further total redesign, one
change being to move the centreline engine to the trailing edge. This near-incredible ma­chine was completed in summer 1933. Ground running of the engines began on 29th June, and it was soon obvious from serious visible oscillation of the tail that the booms were resonating with particular engine speeds. The only evident solution was to re­inforce the booms by adding steel angle gird­ers, and brace the tail with struts. Flight testing by a crew led by pilot M A Snegiryov began on llth August 1933, causing intense public interest over Kharkov. On Flight 9, on 21st November, during speed runs at low alti­tude, resonance suddenly struck and the right tail boom fractured. The aircraft dived into the ground and burned, killing the pilot, 13 crew and a passenger; five crew survived. Kalinin was sent to a new factory at Voronezh. Here
a plan was organised by P I Baranov to build two improved K-7s with stressed-skin booms of rectangular section, but this scheme was abandoned in 1935, the K-7 no longer being thought a modern design.

The basis of this huge bomber was the enormous wing, of typical Kalinin plan form. It had CAHI (TsAGI) R-II profile, with a thick – ness/chord ratio of 19 per cent, rising to 22 per cent on the centreline, where root chord was 10.6m (34ft 9%in) and depth no less than 2.33m (7 ft 7%in). The two main and two sub­sidiary spars were welded from KhMA Chro – mansil high-tensile steel, similar lattice girder construction being used for the ribs. The wing was constructed as a rectangular centre sec­tion, with Dl skin, and elliptical outer sections covered mainly in fabric. A small nacelle of Dl stressed-skin construction projected from

the leading edge. On the leading edge were six 750hp M-34F water-cooled V-12 engines, each with a radiator underneath, and driving a two-blade fixed-pitch propeller; a seventh engine was on the trailing edge. Walkways along the wing led to each engine, and on the ground mechanics could open sections of leading edge to work on the engines without needing ladders. Metal tanks in the wings housed 9,130 litres (2,008 Imperial gallons, 2,412 US gallons) offuel. Just outboard of the innermost engines were the booms holding the tail, 11 .Om (36ft P/in) apart, each having a triangular cross-section with a flat top. The el­liptical horizontal tail carried twin fins and rudders 7.0m (22ft 11 Jfin) apart. All flight con­trols were driven by large servo surfaces car­ried downstream on twin arms. Under the wing, in line with the booms, were extraordi­nary landing gears. Each comprised an in­clined front strut housing a staircase and a vertical rear strut with an internal ladder. At the bottom these struts were joined to a huge gondola. Each gondola contained three large wheels, one in front and two behind, holding the aircraft horizontal on the ground. In front of and behind the front wheels were bomb bays with twin doors. Maximum bomb load was no less than 19 tonnes (41,8871b). De­fensive armament comprised a 20mm can­non in a cockpit in the nose, two more in the ends of the tail booms and twin DA machine guns aimed by gunners in the front and rear of each gondola. Total crew numbered 11, all linked by an intercom system.

Though a fantastic and deeply impressive aircraft, the K-7 was flawed by its designer’s inability to solve the lethal problem of har­monic vibration. Even without this, it would probably have been a vulnerable aircraft in any war in which it might have taken part.

Purpose: To create a safe and easily flown light aeroplane.

Design Bureau: OKB-15 5 ofAI Mikoyan.

Previously famous for a succession of high – performance fighters, the MiG bureau began to relax as the Great Patriotic War ended. Without any requirement from GUAP, Aeroflot or anywhere else, its principals de­cided to investigate the design of a light air­
craft with an M-ll engine which could re­place the Po-2 (originally designated U-2) as a machine which could be safely flown by any pilot from almost any field. The project was assigned to students at the WA (air force academy) under Col (later Professor) G A Tokayev. The OKB kept a close watch on the design, and soon judged that its slightly swept wing could be useful in assisting the design of future jet fighters. The main ele­ments ofthe design were settled by July 1945, and thereafter construction was rapid. The aircraft was named Utka (duck) because of its canard configuration. Aleksandr Ivanovich Zhukov made the first flight on 19th Novem­ber 1945. The wingtip fins and rudders proved unsatisfactory, and for the next six months the MiG-8 was modified repeatedly, as ex­plained below. Its flight testing was handled by OKB pilot Aleksei Nikolayevich Grinchik, assisted by I Ivashchenko and other pilots of the LII MAP (Ministry Flight Research Insti­tute). By the summer of 1946 the MiG-8 was considered more or less perfect. No explana­tion is available for the fact that this aircraft never went into production as the Po-2 re­placement. The MiG-8 was used for many years as the OKB’s communications aircraft, and also as a test-bed for various kinds of re­search.

The MiG-8 was a small cabin aircraft distin­guished by a pusher engine at the tail, a ca­nard foreplane and a high-mounted wing at the rear. Construction was of wood, mainly pine, with ply skin over the fuselage, wing leading edge and fixed foreplane. The wing had Clark Y-H section, with a thickness/chord ratio of 12 per cent. In plan the wings were un­tapered but swept back at 20°, with V-struts to

the bottom ofthe fuselage. The fuselage com­prised a cabin with a door on each side, ta­pering at the rear around the M-11F radial engine rated at HOhp, driving a 2.36m (7ft 9in) two-blade wooden propeller. A total of 195 litres (43 Imperial gallons) of fuel was housed in aluminium tanks in each wing. At the front of the cabin a Po-2 instrument panel was installed for the pilot, and two passenger seats were added behind, with a small space for luggage behind them. Ahead of the cabin a slender nose was added to carry the delta foreplane, fixed at 3° incidence. This was fit­ted with fabric-covered elevators provided with trim tabs, with movement of ±25°. Total foreplane area was 2.7m2 (29ft2). On the outer wings were fabric-covered ailerons, ahead of which were large fixed slats on the leading edge. On the wing tips were delta-shaped fins carrying one-piece rudders, with a total com­bined area of 3m2 (32.3ft2). All control sur­faces were operated by rods and bellcranks. The landing gear comprised a levered-sus – pension nose unit with a 300x150mm tyre, and spatted mainwheels with 500 x 150mm tyres and pneumatic brakes on cantilever legs pivoted to the strut attachment bulk­head, with bungee shock absorbers in the fuselage. Provision was made for skis, but no photographs show these fitted. The first flight showed that directional stability was poor. The wing was given 1 ° anhedral, and the fins and rudders were moved in to 55 per cent of the semi-span and mounted vertically, with a mass balance projecting ahead from the bot­tom of each rudder. The spats were removed, and a new nose gear was fitted with the same wheel/tyre as the main units. Later the wing anhedral was increased to 2°. Considerable attention was paid to engine cooling, and eventually the projecting cylinders were fitted with individual helmets, though no pho­tographs have been found showing this (they were eventually removed except over the two bottom cylinders). In its final form the MiG-8 had a single fuel tank between the fire­wall and engine. An important further modifi­cation was to remove the slats, and photographs also show that in the final con­figuration the wingtips were angled down­wards. At one time the entire aircraft was covered with tufts to indicate the airflow. In its final form the MiG-8 was nice to fly, and re­covery from a spin was achieved merely by releasing the flight controls.

Despite its unusual configurationthe MiG-8 was eventually developed into an excellent aircraft, safe to fly and easily maintained, though at the end of the day it was j udged that future jet fighters should not have a canard configuration. No explanation has been given for the fact that the MiG-8 never led to pro­duction utility, ambulance or photographic aircraft.

Purpose: Technology test-bed to support the 1.42 multirole fighter.

Design Bureau: ANPK (Aviatsionny i Nauchno-Promishlennyi Kompleks) MiG, now the main design unit of RSK ‘MiG’.

In 1983 the large and powerful MiG OKB began general parametric study of an MFI (Mnogofunktsionahl’nyi Frontovoi Istrebitel, multirole tactical fighter). This was to be a to­tally new aircraft as ahead of global competi­tion as the MiG-29 had been. It was to be larger than the MiG-29, to serve as a succes­sor to the long-range MiG-31 and MiG-31M interceptors, but also with the supermanoeu­vrability needed for close combat and the ability to fly air-to-ground missions as well. In 1986 the Council of Ministers issued a direc­tive ordering MiG, Sukhoi and Yakovlev to make proposals for a ‘fifth-generation’ fighter to counter the threat posed by the USAF’s Ad­vanced Tactical Fighter, which later led to the F-22A Raptor. The WS called the require­ment I-90 (Istrebitel, fighter, for the 1990s). The MiG project staff eventually settled on two configurations, called Izdelye (product) 1.41 and 1.43. After prolonged discussion with the WS, features of both were combined in the 1.42. In late 1986 contracts were placed for a static-test airframe, a dynamic and fa­tigue-test airframe and two flight articles, as well as for the totally new AL-41F engine,

N-014 radar and various special test rigs. Supervised by General Constructor Rostislav Apollosovich Belyakov, detailed design pro­ceeded under Chief Project Engineer Grigorii Sedov, later succeeded by Yuriy Vorotnikov. So great was the designers’ faith in the 1.42 that complete manufacturing documentation and software was completed at an early stage. Largely computerised manufacturing began at the Mikoyan experimental shop in 1989. The first flight article, designated 1.44, is a simplified technology demonstrator to prove the aerodynamics and flying qualities, performance and propulsion. Compared with the 1.42 it has an almost pure delta wing (in­stead of a cranked leading edge) and a slight­ly different air inlet system, and lacks the radar, mission avionics and internal weapons bay. By 1991 the 1.44 was structurally com­plete, but was awaiting flight-cleared en­gines, the agregat (accessory gearbox) and several other components. By this time col­lapse of the Soviet Union had begun to cut off funding and seriously delay the programme. The original first-flightdate of1991 -92 was for­gotten, but in December 1994 the 1.44 was completed and brought by road to the OKB’s flight-test facility at the Zhukovskii NIl-WS (air force flight-test institute). On 15th De­cember 1994 Roman Taskaev, then Chief Test Pilot, began fast taxying trials. Though sever­al crucial elements had not been cleared for
flight it was hoped to display the aircraft ‘Blue 01’ at the MaKs 1995 show in August 1995. However, in May 1995 the hope of imminent flight trials was dashed when ANPK MiG be­came part of MAPO, whose sole interest was producing aircraft, such as the MiG-29 and various other types (by no means all of MiG design) to raise money. Things changed in September 1997, when Sukhoi flew the rival S-37 and Mikhail Korzhuyev was appointed ANPK MiG’s General Director. He was deter­mined not to let this rival, and possible link to the next generation, languish in its hangar any longer. In December 1995 he got the WS to declassify photographs taken on first rollout in 1994. He then obtained permission for guests, including Defence Minister Igor Sergeyev, to walk round the 1.44 on 12th Jan­uary 1999. On that occasion the aircraft rolled out under its own power (with astonishing quietness), Vladimir Gorboonov in the cock­pit. At least one observer was impressed, Air Force/Air-DefenceForce C-in-CCol-GenAna – toliy Kornookov saying ‘This aircraft can do everything you want it to’. Gorboonov began the much-delayed flight-test programme on 15 February 2000, Korzhuyev saying ‘We can make the first five or six flights without exter­nal financing’.

The 1.44 is an extremely large single-seater, designed to fly significantly faster than any air­craft it might encounter. Each wing is an al­
most pure cropped delta with a thickness/ chord ratio of about 3.5 per cent and leading – edge angle of about 48° (50° over the inner­most section). On the leading edge are almost full-span hinged flaps, while on the trailing edge are large inboard and outboard flaperons driven by power units in underwing fairings. Unlike the MiG-29, the wing is not blended into the fuselage, nor does it have a LERX (leading-edge root extension). As far forward as possible without interfering with pilot view are enormous canard foreplanes, driven over a large angular range. Each has a sharp dogtooth, and a second smaller dog­tooth due to the fact that these are 1.42 ca­nards which do not perfectly match the large bulging fixed roots of the 1.44. Like the MiG – 29 a structural beam projects behind each wing to carry the outward-sloping upper fins, but these beams are much further apart. Thus, there is now a wide space between the beam and the adjacent engine, and in this is placed a secondary elevator, driven by a pow­erful actuator in a projecting fairing. Each fin has an inset rudder, and under the beams are vertical underpins with powered rudders. The basic aircraft is designed to be longitudinally unstable and to fight at alphas (angles of at­tack) up to at least 100°, which explains the unprecedented 16 flight-control surfaces. These are needed because, unlike the F-22 (say Mikoyan) the basic aircraft is designed for close air combat. At high alphas powerful lift is generated by the canards and by the flat nose and huge flat underside of the fuselage. Absence of LERXs means that, instead of there being an inlet under each wing, there is a single giant rectangular inlet a considerable distance below the forward fuselage. In view of the high design Mach number, the upper wall is fully variable, the sides are cut sharply back in side view, and the lower lip hinges down in high-alpha flight. The ducts diverge immediately to pass the nose gear, and then rise over the weapons bay (in this prototype occupied by instrumentation). The faces of the engines cannot be seen externally. The Saturn (Lyul’ka) AL-41F augmented tur­bofans are quite close together. Prototype engines were made available because, un­like the S-37, the Mikoyan aircraft is the offi­cial choice as the next-generation fighter. Dry and maximum ratings are approximately 12,000kg (26,455 Ib) and 20,000kg (44,090 Ib). This engine, said General Designer Dr Viktor Chepkin, was designed for ‘the new tactical fighters of the 1990s’. In 1993 he told co-au­thor Gunston that the dry weight ofthe AL-41F is ‘about the same as that of the previous-gen­eration engines with half the power’, the ac­tual T/W (thrust:weight ratio) being 11.1 compared with 8 for the AL-31F. On the pub­lic rollout of the 1.44 the engines were aston­ishingly quiet. By 1997 a total of27 AL-41 and AL-4 IF engines had run, and extensive flight testing had taken place under a Tu-16 and in the left position of a MiG-25. T/W ratio of the clean aircraft is no less than about 1.33. The nozzles are circular, with petals giving a vari­able convergent/divergent profile, their inner faces being coated with a tan-coloured ce­ramic. Each nozzle can be vectored over lim­its of ±15° vertically and ±8° horizontally. In the nose is a forked pair of pilot tubes. The canopy swings up and back on four parallel arms. Above the huge wing the fuselage has visible waisting, and the broad but shallow central spine (which can readily be enlarged

if necessary) terminates in a capacious bay for a braking parachute. The landing gears all have levered trailing-link suspension, the sin­gle-wheel main units swinging forward into compartments beside the ‘weapons bay’ and the steerable twin-wheel nose unit retracting backwards to lie between the ducts. There is no problem with nosewheel slush entering the ducts, the height of the landing gears being dictated by landing attitude. Though Blue 01 has the full Avionika KSU-I-42 digital control system, which interlinks all the flight controls and engine nozzles, it does not have the intended Fazotron N-014 (beetle) multi­mode radar nor the aft-facing radar and coun­termeasures which in the 1.42 would occupy the two tailcones. In an armed aircraft provi­sion would be made for a heavy load of weapons internally and on wing pylons (the 1.44 has hardpoints for six), and also for a 30mm gun. Dielectric flush antennas face in all directions, though in the 1.44 many are empty. The 1.44 lacks a RAM (radar-ab­sorbent material) coating, but Mikoyan claim the RCS (radar cross-section) of the MFI would be ‘similar to that of the smaller F-22’.

Had the MFI progressed according to its

original schedule it could well have been, if not a world-beater, at least a formidable rival to the much slower F-22. As it is, unless ANPK MiG can find a rich foreign partner, it could gradually be overtaken by foreign competi­tors. In any case, the days when MiGs sold partly because of their low price are over. Several analysts consider that a production MFI would have to be priced at not less than US$100 million. Indeed, Korzhuyev has gone so far as to suggest that, instead of being one step away from a production MFI, the 1.44 must be regarded as ‘a flying laboratory to as­sist the development of a new fighter that will be smaller and cheaper’.

Purpose: To evaluate a wingless jet VTOL aircraft.

Design Bureau: Aram Nazarovich Rafaelyants, chief engineer of GVF (civil air fleet) repair and modification shops at Bykovo.

Rafaelyants was working at Bykovo, on the Volga, in 1929-59. He had previously pro­duced two lightplanes, flying his RAF-2 to Berlin in 1927. In 1941 his RAF-1 Ibis transport nearly went into production. He worked on many aircraft, and after 1945 handled pro­jects concerned with jet engines and their testing. The Rolls-Royce Thrust Measuring Rig (‘Flying Bedstead’) of 1953 inspired him to produce the Turbolyot. This was flown teth­ered to a gantry in early 1957, and was pub­licly demonstrated in free flight in October of that year. Nearly all the flying was done by he­licopter test pilot Yu A Garnayev. Because of its historical interest, the Turbolyot is today stored in the WS museum at Monino, al­though it was not a WS aircraft but a civilian flying test rig.

The engine selected was the Lyul’ka AL-9G, a single-shaft turbojet rated at 6,500kg (14,330 Ib). This was mounted vertically in the centre of a cruciform framework of welded steel tube. The engine had special bearings
and lubrication, and was fitted with a high – capacity bleed collector ring. On each side was a fuel tank, with fuel drawn equally from both. In front was the enclosed pilot cab, with a door on the right. The bleed system served four pipes, one to each extremity of the vehi­cle, where downward – and upward-pointing nozzles were provided with a modulating valve under the management of the pilot’s control column. The same system also oper­
ated rods and levers governing a two-axis tilt­ing deflector ring under the engine nozzle. Each of the four main structural girders was provided with a long-stroke vertical landing leg with a castoring wheel.

This device never crashed, and provided a solid background of data for the Yak-36 and subsequent jet-lift aircraft.

Purpose: To create a strategic reconnaissance aircraft.

Design Bureau: OKB-256, Podberez’ye, Director P V Tsybin.

As noted previously, the 2RS was launched as a project in January 1956. It was to be a mini­mum-change derivative of the RS, carried to high altitude under the Tu-95N and subse­quently powered by two RD-013 ramjets. However, it was decided that such an aircraft would be operationally cumbersome and in­flexible, and that, despite a very substantial reduction in operational radius, it would be preferable to switch to conventional after­burning turbojets and take off from the ground. The revised project was called RSR (described later). The Ministry gave this the go-ahead on 31st August 1956, but work on
the 2RS continued until is was terminated in early 1957. As it was no longer needed, Tupolev then stopped the rebuild of the Tu – 95N carrier at Factory No 18 at Kuibyshev.

The 2RS would have differed from the RS principally in having the canard foreplanes re­placed by slab tailplanes. Behind these was installed a braking parachute. Provision was made for large reconnaissance cameras in the fuselage ahead of the wing. Surviving drawings (below) also show provision for a 244N thermonuclear weapon, this time as a free-fall bomb recessed under the fuselage further aft. Carrying this would have moved the main landing gear unacceptably close to the tail.

Though there was much to be said for air launch, the basic concept looked increasing­ly unattractive.

Purpose: To create an improved reconnaissance aircraft.

Design Bureau: OKB-256, Podberez’ye, Director P V Tsybin.

The preliminary project for the revised aircraft, able to take off in the conventional manner, was dated 26th June 1957. Design proceeded rapidly, and in parallel OKB-256 created a sim­plified version, using well-tried engines, which could be got into the air quickly to provide data (see NM-1, next). These data became avail­able from April 1959, and resulted in significant changes to the RSR (see R-020). The basic de­sign, however, can be described here.

Though the RSR was derived directly from the 2RS, it differed in having augmented by­pass turbojet engines (low-ratio turbofans) and strengthened landing gear for convention­al full-load take-offs. A basic design choice was to make the structure as light as possible by selecting a design load factor of only 2.5 and avoiding thermal distortion despite local skin temperatures ofup to 220°C. By this means the use of steel and titanium was almost eliminat­
ed, though some skins (ailerons, outer wing and tail torsion boxes) were to be in alumini – um/beryllium alloy. As before, the wing had a t/c ratio of 2.5 per cent, 58° leading-edge sweep and three main and two secondary spars. The tips, 86mm deep, carried Solov’yov D-21 bypass engines. These bore no direct re­lationship to today’s D-21A1 by the same de­sign team. They were two-shaft engines with a bypass ratio of 0.6, and in cruising flight they were almost ramjets. Sea-level dry and aug­mented ratings were 2,200kg (4,850 Ib) and 4,750kg (10,472 Ib) respectively. Dry engine mass was 900kg (l,9841b) and nacelle diame­ter was 1.23m (4ft 1/2in). The fuselage had a fineness ratio of no less than 18.6, diameter being only 1.5m (4ft 1 lin). All tail surfaces had a t/c ratio of 3.5 per cent, and comprised a one- piece vertical fin with actuation limits of ±18° and one-piece tailplanes with limits of + 10°/-25°. All flight controls were fully pow­ered, with rigid rod linkages from the cockpit and an artificial-feel system. The main and steerable nose landing gears now had twin wheels, and were supplemented by single­
wheel gears under the engines, all four units hydraulically retracting to the rear. A braking parachute was housed in the tailcone. A total of 7,600kg (16,755 Ib) of kerosene fuel was housed in integral tanks behind the cockpit and behind the wing, plus 4,400kg (9,700 Ib) in two slender (650mm, 2ft 1 V-im diameter) drop tanks. An automatic trim control system pumped fuel to maintain the centre of gravity at 25 per cent on take-off, 45.0 in cruising flight and 26.4 on landing. In cruising flight the cock­pit was kept at 460mm Hg, and the pilot’s pres­sure suit maintained 156mm after ejection. An APU and propane burner heated the instru­ment and camera pallets which filled the cen­tre fuselage, a typical load comprising two AFA-200 cameras (200mm focal length) plus an AF A-1000 or AFA-1800 (drawings show four cameras), while other equipment included optical sights, panoramic radar, an autopilot, astro-inertial navigation plus a vertical gyro, a radar-warning receiver and both active and passive ECM (electronic countermeasures) During construction this aircraft was modi­fied into the RSR R-020.

RSR inboard profile

Purpose: To destroy enemy armour.

Design Bureau: A A Arkhangelskiy (Tupolev aide), with G M Mozharovskiy and IV Venevidov, Factory No 32, Moscow.

The idea was that of Mozharovskiy-Venevi – dov, who called their project the Kombain (combine) because of its versatility. They were long-time specialists in aircraft arma­ment, among other things being responsible for all the early gun turrets in the Soviet Union. Arkhangelskiy increased their political power and got them a separate design office and factory for what became called the BSh (ar­moured assaulter, the same designation as the Ilyushin Stormovik) and also KABV (com­bined artillery-bomber weapon). The eskiz – nyi proekt (sketch project) was submitted on 29th December 1940, long-lead materials were sanctioned on 25th January 1941 and the project was confirmed at the NIl-WS by AIFilin on 12th March 1941. Despite being (on paper) superior, it was terminated in the evacuation of the designers from Moscow to Kirov later in 1941, all effort being put into the Ilyushin aircraft (which was built in greater numbers than any other aircraft in history).

The whole emphasis in the M-V project was giving the pilot (the only occupant) the best possible view ahead over the nose. Whereas
the engine of the IL-2 Sturmovik blocked off the view at a downwards angle of 8°, the M-V aircraft gave the pilot a downwards view of 30°. This is because the engine (the l,625hp AM-38, the same as the IL-2) was behind the cockpit. The tail was carried on twin booms and the landing gear was of the then-novel nosewheel type. Many armament schemes were planned, including one Taubin 23mm gun and four ShKAS, or four ShVAK, all mounted on pivots to fire diagonally down. Up to 500kg of bombs could also be carried, mainly to comprise AO-20 or AO-25 fragmen­tation bomblets.

On the basis of written evidence this air­craft would have been a better tank killer than the Ilyushin machine. The drawback was that

BSh-MV

when the Ilyushin suffered heavy attrition from German fighters a backseater was put in to defend it, and this would have been diffi­cult with the BSh/M-V.

Purpose: To test designer’s experimental wing.

Design Bureau: Aircraft constructed by BOK to design of S S Krichevskii.

Sawa Syemenovich Krichevskii, called ‘a tal­ented designer’ by historian Shavrov, spent the early 1930s trying to create the most effi­cient aeroplane wing. He made many tunnel models, eventually settling on a wing of high aspect ratio constructed in front and rear sec­tions. The rear part was hinged to the front
with a small intervening gap acting as a slot. In flight, the intention was that the pilot would select the optimum angle for the rear portion, Shavrov commenting that ‘this wing could al­ways be flown in a drag-polar envelope’.

Krichevskii secured funding to build a re­search aircraft, called RK (Razreznoye Krylo, slotted wing) and designated BOK-2 by the construction bureau. The BOK-2 was complet­ed in 1935 and flew successfully, but Krichevskii died shortly afterwards. Documen­tation on this aircraft has never been found.

The BOK-2 was an extremely neat can­tilever monoplane, with a single M-l 1 engine rated at 11 Ohp. Shavrov comments that ‘The wing skin was polished to mirror brilliance [suggesting all-metal construction]…it is hard to say if its excellent performance was due to its drag-polar envelope or to its perfect aerodynamic shape’.

Despite its apparently excellent perfor­mance the RK appears to have had no impact on the Soviet aviation ministry.

No data available.

Purpose: To create a multirole aircraft with tailless configuration.

Design Bureau: OKB ofK A Kalinin, Voronezh.

In April 1933 Kalinin submitted to the NIl-WS three prelim inary designs for aVS-2 (Voiskovoi Samolyot, troop aircraft) for reconnaissance, bombing, transport, ambulance and other missions. One was conventional, the second had twin tail booms, and the third was tail­less. Kalinin preferred the third option, be­cause of supposed lower weight and drag, better manoeuvrability and ease of Fitting a tail turret for defence. He began with the NACA R-106R aerofoil, with slats, park-bench
ailerons, Scheibe wingtip rudders and a vesti­gial horizontal tail. Tunnel testing of models led to an improved design with a trapezoidal wing ofCAHI (TsAGI) R-II profile, with trailing – edge servo-operated elevators and ailerons of Junkers ‘double wing’ type (as also used by Grokhovskii), the small horizontal tail being eliminated. To test the configuration a half­scale glider (span 10.45m, length 5.2m) was constructed in 1934 and flown over 100 times by V O Borisov. After many problems and ar­guments, the full-scale aircraft was complet­ed at GAZ (State Aviation Factory) No 18 at Voronezh as the K-12, and flown by Borisov in July 1936. Factory testing was completed in 46 flights. The K-12 was then ferried to

Moscow where its Nil testing was assigned to P M Stefanovskii from October 1936. He found severe control problems, and eventu­ally N N Bazhanov, head of the NIl-WS, re­fused to accept the K-12 for official trials. From this time onwards Kalinin was under a cloud. The Director of GAZ No 18 joined with Tupolev, Vakhmistrov (see later) and others to impede progress and get the K-12 aban­doned. Kalinin moved into Grokhovskii’s summer dacha, the K-12 languishing at Grokhovskii’s KB-29. Contrary to the political tide, Voroshilov ordered the K-12 to fly in the 1937 Air Day parade over Moscow Tushino, and Bazhanov had it painted in a fantastic red/yellow feathered scheme as the Zhar

Ptitsa (firebird or phoenix). It made a great impression, and on 12th December 1937 the Assistant Head of the WS, YaVSmushke – vich, signed an order for renewed NIl-WS testing to start on 1st March 1938, followed by series production of modified aircraft at GAZ No 207. Work began, but in spring 1938 Kalin­in’s enemies managed to get him arrested and shot on charges of spying and conspira­cy. As he had become an ‘enemy of the peo­ple’ the contract was cancelled, the K-12 was scrapped and the ten aircraft on the assembly line were never completed.

The structure of the K-12 was almost en­tirely based on welded KhMA (Chromansil steel) tubing. The wing comprised left and right panels bolted to the roots, each having one main spar running straight from tip to tip. The fuselage was in three bolted sections, the front section being mainly skinned in Dl, all the rest of the skin being fabric. The trailing – edge and wingtip controls were all fabric­skinned Dl. The main landing gears were to have been retractable, but the intended M-25 engines and variable-pitch propellers were not available in time, so weight was saved by making the landing gears fixed. The inadequate engines which had to be fitted were 480hp M-22 (Bristol Jupiter licence), in cowlings with cooling gills, and driving 2.8m
(9ft 2%n) two-blade metal propellers with pitch adjustable on the ground. Crew com­prised a pilot in an enclosed cockpit, a navi­gator who also served as bomb aimer in a nose turret with one 7.62mm ShKAS (he was provided with a rudimentary flight-control lever in case the pilot was incapacitated) and a radio operator in a similar tail turret. Bombload of up to 500kg (l,1021b) was car­ried on a KD-2 vertical rack behind the main spar and pilot’s cockpit. Other equipment in­cluded a V SK-2 radio and AF A-12 camera.

At the end of its life, in early 1938, the K-12 was refitted with 700hp M-25 (Wright Cy­clone) engines, driving Hamilton Standard type variable-pitch propellers, but it was never tested in this form. Other modifications included fitting an electrically retractable main landing gear and modified armament. It had also been Kalinin’s intention to replace the wingtip fin/rudder surfaces by rudders above the wings behind the engines, but these were never fitted.

Accounts of this strange tailless aircraft tend either to be strongly positive or strongly negative. There is no doubt Kalinin was the victim of political intrigue, but at the same time the K-12 does not appear to have been a stable or controllable aircraft.

Top: K-12 inboard profile.

Above and right: Two views of Zhar Ptitsa.

Purpose: To boost the speed of a piston – engined fighter.

Design Bureau: The OKB-155 ofAI Mikoyan.

In 1942 the Central Institute for Aviation Mo­tors (often abbreviated as TsIAM) began to develop an unusual method of boosting the propulsive power of fighter aircraft. Called VRDK (from Russian for ‘air reaction auxiliary compressor’) it involved adding a drive from the main engine to an auxiliary compressor for a flow of air rammed in at a forward-fac­ing inlet. The compressed air was then ex­pelled through a combustion chamber and propulsive nozzle. This scheme was worked on by a team led by V Kh Kholshchevnikov. In January 1944 the governments of the UK and USA announced their possession of jet air­craft. In a near-panic response, the GKO (State Committee for Defence) ordered all the main Soviet fighter OKBs to build jet air­craft. Stalin criticised designers for not al­ready having such aircraft. As the only Soviet turbojet (the Lyul’ka VRD-2) was nowhere near ready for use, MiG and Sukhoi were as­signed the urgent task of creating prototype fighters to use the VRDK booster system. Both quickly came to the conclusion that the VRDK method could not readily be applied to any of their existing fighters, and both designed spe­cial (quite small) fighters to investigate it. The MiG aircraft was called N by the OKB, and given the official designation I-250. The pro­ject was assigned to G Ye Lozino-Lozinskii. A mock-up was approved on 26th October

1944, and after frantic effort the ‘N’ Nol was rolled out painted white on 26th February

1945. OKB pilot A P Dyeyev began the flight – test programme on 3rd March. Soon the magic 800km/h mark was exceeded, and Mikoyan presented Dyeyev with a car. VRDK operation was generally satisfactory but deaf­eningly noisy. On 19th May a tailplane failed at low level and the ‘N’ Nol crashed. By this time ‘N’ No2 was almost ready to fly. Painted dark blue, with a yellow nose and horizontal streak, it was restricted to 800km/h to avoid a repetition ofthe failure. Stalin had meanwhile ordered that a ‘regiment’ of ten of these air­craft should fly over Red Square on 7th No­vember, October Revolution Day. ‘N’ No 2 was tested by LII pilot A P Yakimov, assisted by OKB pilot A N Chernoburov. This aircraft was written off in a forced landing in 1946. The hastily built ten further I-250s were tested by IT Ivashchenko. On 7th November nine were ready, but the flypast was cancelled be­cause of bad weather. In late 1946 Factory No 381 was given an order for 16 fully equipped fighter versions, designated MiG – 13. Factory testing of these took place in May-

July 1947,1 M Sukhomlin carried out NIl-WS testing between 9th October 1947 and 8th April 1948, and these aircraft were then deliv­ered to the A V-MF. They served with the Baltic and Northern Fleets until 1950.

Aircraft N bore little similarity to any previ­ous MiG design. Made entirely of metal, with a stressed-skin covering, it was smaller than most fighters, whereas its predecessors had been larger. The straight-tapered wing had a CAHI 10%-thick laminar aerofoil, with two spars and plate ribs. Movable surfaces com­prised two-part Frise ailerons and hydrauli­cally operated CAHI slotted flaps. The fuselage was relatively deep to accommodate the unique propulsion system. The engine was a VK-107, rated at l,650hp for take-off and l,450hp at 3,500m (12,470ft). At the front it was geared down to drive the AV-5B three – blade constant-speed propeller of 3.1m (10ft 2in) diameter. At the back it drove the en­gine’s own internal supercharger as well as a clutch which, when engaged, drove through 13:21 step-up gears to a single-stage axial compressor. This pumped air through a large duct from a nose inlet. Just behind the com­pressor was the engine’s cooling radiator. Be­hind this were seven nozzles from which, when the auxiliary compressor was engaged, fuel from the main tanks was sprayed and ig­nited by sparking plugs. The resulting flame filled the large combustion chamber, from which a high-velocity jet escaped through a two-position nozzle. Downstream of the burners the entire duct was refractory steel, and when the VRDK was in operation its walls were cooled by water sprayed from a 78 litre (17 Imperial gallon) tank, the steam adding to the thrust. At 7,000m (22,966ft) the VRDK was estimated to add l,350hp, to a total of 2,500hp. The oil cooler surrounded the pro­peller gearbox, with flow controlled by gills round the top of the nose. The engine was mounted on a steel-tube truss. Fuel was housed in three self-sealing tanks, one of 415 litres (91.3 Imperial gallons) in the fuselage and one of 100 litres (22.0 Imperial gallons) in each wing. The large central tank forced the cockpit to be near the tail, with a sliding canopy. The metal-skinned tail was repeat­edly modified, the small elevators having a tab on the left side. A unique feature of the main landing gear was that the wheels were carried on single levered-suspension arms projecting forward from the leg. The tail – wheel was fully retractable. Even the first air­craft, called ‘N’ Nol, was fully armed with three B-20 cannon, each with 160 rounds. The MiG-13 batch differed in having a larger verti­cal tail, larger fuel and water tanks, RSI-4 radio with a wire antenna from the fin to a mast projecting forwards from the wind­screen, and (temporarily) strange curved pro­peller blades in an attempt to reduce tip Mach number.

These aircraft performed as expected, but were a dead-end attempt to wring the last bit of performance from piston-engined fighters.

Photographs on the opposite page:

Top: I-250 Nol.

Centre: I-250 No 2.

Bottom: Production MiG-13 (straight propeller blades).