Category Soviet x-plenes

Nikitiii Shevcheiiko IS-2

 

Purpose: Improved version of IS-1 Design Bureau: OKB-30, chief designer V V Shevchenko

The initial funding allocated to Shevchenko’s project actually paid for two prototypes. Though construction of both began in parallel it was soon decided to incorporate improve­ments in the dubler (second aircraft). Desig­nated IS-2, and also known as the I-220t>/s, this emerged from GAZ No 156 in early 1941. Surviving documents differ. One account states that the IS-2 ‘was ready in January 1941…the War broke out and only four test flights were carried out.’ Three other ac­counts, in Russian, French and English, state that the aircraft was completed in April 1941 but had not flown when the Germans invad­ed. Shavrov is non-committal, but notes that all performance figures are estimates. The
walk-round outdoor photos were all taken with snow on the ground.

The IS-2 was a refined derivative of the IS-1. The engine was an M-88 14-cylinder radial rated at l,100hp, neatly installed in a long – chord cowl with a prominent oil-cooler duct underneath and driving a VISh-23 propeller with a large spinner, but retaining Hucks starter dogs. According to Podol’nyi, the fuse­lage cross-section was reduced (which is certainly correct) and, while wing spans re­mained the same, chord was reduced in order to increase aspect ratio and reduce area. Shavrov and a French author state that the wings of the IS-1 and IS-2 were geometri­cally identical. What certainly was altered was that the landing-gear retraction system was replaced by simply connecting the main legs to the wing linkage, so that a single cock­pit lever and a single pneumatic jack folded
the lower wings and the main landing gears in a single movement. It is widely believed that the IS-2 was not intended to fly in combat as a biplane, the benefits being restricted to take-off and landing. In the IS-1 documenta­tion the idea that the aircraft might be operat­ed as a biplane is never mentioned. Ifit were, then what was the point of the folding lower wing? Further modifications in the IS-2 were that the tail was redesigned, the tailwheel could retract and the two inboard ShKAS were replaced by heavy 12.7mm Beresin BS guns.

By the time this aircraft appeared, even though it looked more modern than its pre­decessor, the WS was fast re-equipping with simple monoplane fighters. These unques­tionably stood more chance against the Luft­waffe than the IS-2 would have done.

Span (upper)

8.6 m

28ft rnn

(lower, extended)

6.72 m

22 ft tf in

Length

7.36 m

24 ft P/i in

Wing area (as biplane)

20.83 m2

224ft2

(upper only)

13.0m2

140 ft2

Weights

Loaded, Shavrov’s ‘estimated

2,180 kg’

is probably a misprint for

2,810kg

6,195 Ib

Performance (estimated)

Shavrov’s speed of588 km/h and ceiling of 1,100 m are suspect, and Podol’nyi’s ‘600 km/h’ is even less credible; the only plausible figure appears to be the 507 km/h (315 mph) of the French account.

Nikitiii Shevcheiiko IS-2

Nikitiii Shevcheiiko IS-2

Nikitiii Shevcheiiko IS-2

Views of IS-2.

 

Sukhoi T-58VD

Purpose: To provide full-scale STOL jet-lift data to support the T6-1.

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

Early history of the T6-1 (see page 178) re­volved around how best to create a formida­ble tactical aircraft with a short field length. One of the obvious known methods of mak­ing a STOL (short take-off and landing) air­craft was to fit it with additional jet engines arranged vertically to help lift the aircraft at low speeds. In January 1965 the T-58D-1, the first prototype ofwhat was to become the Su – 15 interceptor, was taken off its normal flight programme and returned to an OKB factory. Here it was modified as the T-58VD, the des­ignation meaning Vertikalnyye Dvigateli, ver­tical engines. Managed by R Yarmarkov, who had been leading engineer throughout T-58D testing, ground running trials of the VD began in December 1966. This work required an enormous test installation built at the OKB-51 which used a 15,000hp NK-12 turboprop to blast air at various speeds past the T-58VD while it performed at up to full power on all five engines. It was mounted on a special
platform fitted with straingauges to measure the thrust, drag and apparent weight. When these tests were completed, the T-58VD was taken to the LII at Zhukovskii where it began its flight-test programme on 6th June 1966. Initial testing was handled by Yevgenii Solov’yov, who was later joined by the OKB’s Vladimir Ilyushin. On 9th June 1967 this air­craft was flown by Solov’yov at the Domodye – dovo airshow, where NATO called it ‘Flagon-B’. Its basic test programme finished two weeks later. It then briefly tested the ogi­val (convex curved) radome used on later Su – 15 aircraft and the UPAZ inflight-refuelling pod. It was then transferred to the Moscow Aviation Institute where it was used as an ed­ucational aid.

The original T-58D-1 was built as an out­standing interceptor for the IA-PVO air-de­fence force, with Mach 2.1 speed and armament of K-8M (R-98) missiles. Powered by two R-l 1F2S-300 turbojets (as fitted to the MiG-21 at that time), each with a maximum afterburning rating of 6,175kg (13,6131b), it had pointed delta wings with a leading-edge angle of 60°, fitted with blown flaps. The wings looked very small in comparison with
the fuselage, which had backswept rectangu­lar variable-geometry engine inlets on each side. To convert it into the T-58VD a com­pletely new centre fuselage was spliced in. This used portions of the original air ducts to the main engines but separated them by new centreline bays for three lift jets. The front bay housed a single RD-36-35 turbojet of P A Kolesov design with a thrust of 2,300kg (5,1801b). One of the wing main-spar bulk­heads came next, behind which was a bay housing two more RD-36-35 engines in tan­dem. Each bay was fireproof and fitted with all the support systems shown to be needed in previous jet-lift aircraft. On top were large louvred inlet doors each hinged upward at the rear, while underneath were pilot-con­trolled cascade vanes for vectoring the lift-jet thrust fore and aft. Another important modifi­cation was to redesign the outer wing from just inboard of the fence, reducing the lead­ing-edge sweep to 45° and extending the aileron to terminate just inboard of the new squared-off tip. Apart from the missile pylons

This page and opposite top: Views of T-58VD, one showing its final use at the MAI.

Sukhoi T-58VD

 

military equipment was removed, and a new telemetry system was fitted with a distinctive twin-blade antenna under the nose.

Sukhoi T-58VDThe jet-lift conversion reduced take-off speed and ground run from 390km/h (242mph) and 1,170m (3,839ft) to a less fran­tic 290km/h (ISOmph) and only 500m (1,640ft). Landing speeds and distances were reduced from 315km/h (196mph) and

1,000m (3,281ft) to 240km/h (149mph) and 600m (1,969ft). This was achieved at the ex­pense of reduced internal fuel capacity and sharply increased fuel consumption at take­off and landing. Moreover, it was discovered during initial flight testing that the longitudinal locations of the three lift engines had been miscalculated. Operation of the front RD-36- 35 caused a nose-up pitching moment which the pilot could not counteract at speeds below about 320km/h (199mph), so this lift engine could not be used on landings.

T-58VD

 

Sukhoi T-58VD

Vakhmistrov Zveno

Purpose: To enable a large aircraft to carry one or more small ones long distances, for example to attack targets that would otherwise be out of reach.

Design Bureau: Not an OKB but engineer Vladimir Sergeyevich Vakhmistrov working at the LII (flight research institute).

In 1930 Vakhmistrov suggested that a cheap glider might be used as an aerial gunnery tar­get, and he quickly perfected a way of carry­ing such a glider above the upper wing of an R-l reconnaissance aircraft and releasing it in flight. This gave Vakhmistrov the idea ofusing a large aircraft to carry a small one on long – range flights over hostile territory. The small aircraft could either be fighters to protect a large bomber, or bomb-carrying attack air­craft or camera-carrying fast reconnaissance aircraft which could make a pass over a target while the parent aircraft stood off at a safe dis­tance. In each case the difficult part was hook­ing on again for the long flight home. After presenting the WS and LII management with calculations Vakhmistrov received permis­sion to try out his idea. This led to a succes­sion of Zveno (link) combinations:

Z-l

This featured a twin-engined Tupolev TB-1 bomber carrying a Tupolev I-4 fighter above each wing. The fighters were of the I-4Z ver­sion, three of which were converted for these experiments with short stub lower wings and attachment locks on the landing gear and under the rear fuselage. The bomber was pro­vided with attachments for the Zveno aircraft above each wing: two small pyramids for the landing gear and a large tripod for the rear – fuselage attachment.

The first flight took place from Monino on 3rd December 1931. The TB-1 was flown by AI Zalevskii and A R Sharapov, with Vakhmistrov as observer. The fighters, with ski landing gears, were flown by V P Chkalov and A S Anisimov. The take-off was made with the fighter engines at full power. The TB-1 copilot forgot the release sequence and released Chkalov’s axle before releasing the aft attachment, but Chkalov reacted instantly and released the rear lock as the fighter reared nose-up. The second fighter was re­leased correctly. For a few seconds the TB-1 flew with no tendency to roll with an I-4Z on one wing.

Z-la

First flown in September 1933, this comprised the TB-1 carrying two Polikarpov I-5 fighters. The latter were fitted with a reinforcing plate under the rear fuselage carrying the rear hold­down, but had no special designation. The pi­lots were P M Stefanovskii (TB-1) and I F Grodz’ and V K Kokkinaki (I-5).

Z-2

This was the first of the more ambitious hook­ups using a TB-3 as parent aircraft. The bomber was an early TB-3/4 M-l 7, and it was given attachments for an I-5 above each wing and a third above the fuselage with its wheels on a special flat platform. On the first test in August 1934 the TB-3 was flown by Zalevskii and the fighters by T P Suzi, S P Suprun and T T Al’tnov.

Z-3

This combination would have hung a Grig – orovich I-Z monoplane fighter under each wing of the TB-3. It was not flown.

Z-4

No information.

The complete sequence of Zveno developments (not all were tried).

Vakhmistrov Zveno

 

Vakhmistrov ZvenoПодпись: Zveno-2Vakhmistrov ZvenoПодпись:Подпись:Vakhmistrov ZvenoZ-5

This was the first attempt to hook back on. The parent aircraft was again the TB-3/4 M-l 7, and the fighter was an I-Z fitted with a large suspension superstructure of steel tubes, plus a curved upper guide rail terminating in a sprung hook releasable by the pilot (almost identical to the arrangement used on the air­ship-borne US Navy F9C Sparrowhawks). This was designed to hook on a large steel-tube trapeze under the bomber, which was folded up for take-off and landing. V A Stepanchy- onok flew the I-Z on several tests with the bomber flown as straight and level as possible by Stefanovskii. The first hook-on took place on 23rd March 1935; this was a world first.

Z-6

The final combination of the original series was the mating oftwo I-16 monoplane fighters hung under the wings ofthe TB-3. The fighters were provided with local reinforcement above the wings to enable them to be hung from sliding horizontal spigots on large tripod links of streamlined light-alloy tube pin-joint­ed to the bomber’s wing structure. Bracing struts linked the bomber to a latch above the fighter’s rear fuselage, and one ofthe fighters (M-25A-engined No 0440) was photographed with a lightweight pylon above the forward fuselage to pick up under the bomber’s wing. The first test took place in August 1935; Ste – fanovskii flew the TB-3 and the fighter pilots were K K Budakov and AI Nikashin.

Aviamatka

Named ‘mother aircraft’, this amazing test, not part of the original plan, took place in No­vember 1935. The TB-3/4M-17 took off from Monino with an I-5 above each wing and an I-16 below each wing. At altitude it folded down the under-fuselage trapeze and Stepan – chenok hooked on the I-Z, making a combi­nation of six aircraft of four types all locked together. After several passes all the fighters released simultaneously. By this time Vakhmistrov had schemes for up to eight fighters of later types all to be carried by large aircraft such as the full-scale VS-2 tailless bomber projected by Kalinin. Instead Stalin’s ‘terror’ caused the whole effort to wither, but there were still to be further developments.

SPB (Russian initials for fast dive bomber) This was a special version of the Polikarpov I-16 equipped with a rack to carry an FAB-250 (bomb of 250kg, 551 Ib) under each wing. Such an aircraft could not have safely taken off from the ground. In 1937 a later TB-3/4AM – 34RN was made available, and two SPB air­craft were hung under its wings. The first test took place on 12th July 1937, the TB-3 being flown by Stefanovskii and the dive bombers by A S Nikolayev and IA Taborovskii.

Z-7

In November 1939 one final combination was flown: the TB-3/4AM-34RN took off with an I – 16 under each wing and a third hooked under the fuselage in flight (with severe difficulty). The I-16 pilots were Stefanovskii, Nyukhtikov and Suprun.

Vakhmistrov Zveno

Подпись: Zveno-6 Vakhmistrov Zveno

In early 1940 the WS decided to form a Zveno combat unit. Based at Yevpatoriya, this was equipped with six modified TB-3/4AM – 34RN and 12 SPB dive bombers. During the Great Patriotic War a famous mission was flown on 25 th August 1941 which destroyed the Danube bridge at Chernovody in Roma­nia, on the main rail link to Constanta. Surviv­ing SPBs flew missions in the Crimea.

Vakhmistrov Zveno

Vakhmistrov Zveno

Vakhmistrov Zveno

BICh-8

Подпись: Cheranovskii with BICh-8.

Purpose: To test the use of wingtip rudders. Design Bureau: B I Cheranovskii.

Few details of this machine have survived. It was built and tested in 1929. Cheranovskii was so distressed by the failure of the BICh-7 that he built this simple glider to see ifwingtip rudders could be made to work.

The BICh-8 was dubbed T reoogol’nik (little triangle). It had an open cockpit and centre­line skid. The wing was built as a centre sec­tion, integral with the nacelle, and outer panels fitted with inboard elevators, outboard ailerons and wingtip rudders with inset hinges mounted on small fins.

This machine may have flown satisfactori­ly, because Cheranovskii repeated tip rud­ders in the BICh-11.

No data.

BICh-8

Florov 4302

Purpose: Rocket-propelled aircraft for aerodynamic research.

Design Bureau: Ilya Florentyevich Florov (1908-83) had a long career at several OKBs and State organizations, some of his products being biplane fighters designed with A A Borovkov. In 1943 he headed a design cell in NIl-WS (air force state test institute).

In 1943 Florov was assigned the task of creat­ing a small rocket-engined aircraft to test wing profiles, flight-control systems and other features. At this time published German pa­pers on swept wings (1935) had not been studied. Three examples of No 4302 were funded, and Nil pilots A F Pakhomov and I F Yakubov were assigned to the programme. The No 1 aircraft was not fitted with an engine, and made 46 flights from late 1946, on each occasion being towed to about 5,000m (16,400ft) by a Tu-2. The No 2 was flown under power, the first take-off (by Pakhomov) being in August 1947. In the same month the programme was terminated, funds being transferred to the MiG I-270. At this time the No 3 aircraft had for some time been com­plete but waiting for its RD-2M-3 engine.

The 4302 was a small aircraft with a fuse­lage dictated by the size of cockpit and pro­
pellant tanks. Construction was entirely light – alloy stressed skin, with a very good surface finish. The untapered wings had a 13-per-cent laminar CAHI (TsAGI) profile devised by G P Svishchev. They were made as one unit attached above the fuselage, with down – turned tips. On each trailing edge were three sections of slotted flap which were also oper­ated in opposition for lateral control. The tail comprised a fixed fin and tailplane, with fixed endplate fins, and manually driven rudder and elevators with inset hinges and mass bal­ances. The pilot had a small pressurized cockpit in the nose with an upward-hinged canopy. The No 1 aircraft was completed with conventional fixed landing gear (using some La-5FN parts), for slow-speed glider flights. The Nos 2 and 3 were designed to take off from a tricycle-gear trolley and land on a cen­treline skid and tailwheel. The No 2 was fitted with a liquid rocket by A M Isayev assisted by L S Dushkin rated at 1,100kg (2,425 Ib) at sea level. In the rear fuselage was a large tank for red fuming nitric acid made of 3mm Enerzh 18-8 stainless, wrapped with OVS wire to withstand gas feed pressure. Behind was the tank ofpetrol (gasoline). Later, in 1947 a more powerful 1,140kg (2,513 Ib) Dushkin engine was fitted. The No 3 aircraft was to have been
fitted with an RD-2M-3 engine developed by Dushkin and V P Glushko, with main and cruise chambers with sea-level ratings of 1,450 and 400kg (3,197 and 882 Ib). In this condition it was to have been designated No 4303. One report says that an RD-2M or RD – 2M-3 was retrofitted to No 2, but there is no record of it flying with this engine.

These aircraft appear to have left no record of aerodynamic achievement.

Dimensions

Span (all) Length (No 2) (No 3)

Wing area (all)

6.932m 7.124m 7.152m 8.85 nf

22 ft 9 in

23 a VA in 23 ft 5% in 95.26ft2

Weights

Empty (No 1)

970kg

2,138 Ib

Loaded (No1)

1,350kg

2,976 Ib

(No 3)

1,750kg

3,859 Ib

Performance

Max speed (No2, achieved) 826km/h

513 mph

Landing speed (all)

125km/h

78 mph

Three-view of 4302 No 3 with

Florov 4302

 

Florov 4302

Florov 4302

Above left: 4302 Nol.

 

Florov 4302Above right: 4302 No 2 in take-off configuration.

Left: 4302 No 2 after landing.

LaGG-3/2 VRD

LaGG-3/2 VRD

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

Design Bureau: The OKB of Lavochkin, Gorbunov and Gudkov (LaGG).

Unknown to the outside world, the Soviet Union was the pioneer of ramjet propulsion. Such engines are essentially simple ducts, with air rammed in at the front inlet, slowed in an expanding diffuser, mixed with burning
fuel and expelled at high speed through a rear converging section and nozzle. In 1939 M M Bondaryuk, at NIl-GVF OKB-3 (civil air fleet research construction bureau No 3) first ran an experimental subsonic ramjet. In Au­gust 1942 a pair of much further developed versions were attached under the wings of LaGG-3 fighter No 31213173 and tested in the air from 5th August. Test pilot Captain Mishenko made 14 flights. Results were indif­
ferent, but provided a background of data for later ramjet work, collated by M V Keldysh.

The LaGG-3 was a mass-produced fighter of all-wood construction, powered by an M – 105PF engine. The first Bondaryuk ramjets to fly were designated VRD-1, and were tested in two forms. The original was a plain steel duct with a diameter of 140mm (51/2in), length of 2,150mm (7ft1/2in)and weight of 16kg (35.31b). The boosted (forsirovannyi) version had a diameter of 170mm (6%in) and length of 1,900mm (6ft Sin), but weighed the same. Fuel from the three main aircraft tanks was supplied by a special BNK-10 pump with a proportioner to supply both ramjets equally.

Results were sufficiently interesting to jus­tify further work, starting with the VRD (or PVRD) 430 (see page 89). In parallel Merkulov was developing the DM-4 and similar ramjets, tested on the I-153 and I-207.

Dimensions

Span 9.81 m 32 ft 2 in

Length 8.82 m 28 ft m in

Wing area 17.62m2 189.7ft2

Weight and performance not recorded.

MiG Experimental Heavy Interceptors

Purpose: To create a supersonic missile­armed all-weather interceptor.

Design Bureau: OKB-155 ofA I Mikoyan

I-3U, I-7U, I-75

In the second half of the 1950s the ‘MiG’ de­sign team created a succession of interceptor fighters which began by reaching 870mph and finished 1,000mph faster than that. The first was the I-1, first flown on 16th February 1955, which resembled a MiG-19 powered by a single large VK-7 centrifugal engine. After a major false start, this led to the I-3U, which (contrary to many reports) was flown in late 1956 on the 8,440kg (18,607 Ib) thrust of a VK- 3 bypass jet (low-ratio turbofan). By this time the aerodynamic shape, and indeed much of the structure and systems, was extraordinari­ly similar to the contemporary Sukhoi proto­types. The next stage was the I-7U, flown on 22nd April 1957, which used the engine picked earlier by Sukhoi, the excellent Lyul’- ka AL-7F rated at 9,210kg (20,304Ib). In turn this was rebuilt into the I-75, first flown on 28th April 1958. This was the first of the fami­ly of impressive MiG single-engined heavy in­terceptors, with powerful radar (Uragan [hurricane] 5B) and armed only with missiles (two large Bisnovat K-8). A second aircraft was built from scratch, designated I-75F and powered by the uprated AL-7F-1 with a max­imum thrust of 9,900kg (21,8251b). The fol­lowing specification refers to the I-75.

Dimensions Span Length Wing area

9.976 m 18.275m 31.9m2

32 ft 9n in 59 ft 1Г in 343 ft2

Weights

Empty

8,274 kg

18,241 Ib

Internal fuel

2,100kg

4,630 Ib

Loaded (clean)

10,950kg

24,1 40 Ib

(maximum)

11,470kg

25,287 Ib

Performance Maximum speed

clean, at 1 1 ,000 m (36,089 ft) 2,050 km/h

1,274 mph (Mach 1.93)

with missiles

1,670 km/h

1,038 mph (Mach 1.57)

Time to climb to 6,000 m (19,685 ft)

0.93min

Service ceiling (Mach 1 .6 in afterburner)

1 9, 1 00 m

62,664 ft

Range (internal fuel)

1 ,470 km

913 miles

Take-off run

1,500m

4,921 ft

Landing speed/run

240 km/h

149 mph

with parabrake

1,600m

5,249ft

Ye-150

This was built specifically to test the remark­able R-15 turbojet, created by S KTumanskii, initially working in A A Mikulin’s KB, which he took over in 1956. This engine had been or­dered to power future aircraft flying at up to Mach 3 (the first application was a Tupolev cruise missile). The MiG team led by Nikolai Z Matyuk predictably adhered to the proven formula of a tube-like fuselage with a variable multi-shock nose inlet, mid-mounted delta wing (the I-75 had had swept wings) and mid­mounted swept one-piece tailplanes. This time the fuselage had to accept the R-15-300 en­gine’s take-off airflow of 144kg (317.51b) per second, and the dry and reheat ratings of this engine were 6,840kg (15,080 Ib) and 10,150kg (22,3771b). At high supersonic Mach numbers the thrust was greatly increased by the ejector – type nozzle, a very advanced propulsion sys­tem for the 1950s. As the Ye-150 was not a fighter the cockpit was enclosed by a tiny one – piece canopy of minimum drag. After pro­longed delays, mainly caused by the engine, the aircraft was flown by A V Fedotov on 8th July 1960. It required frequent engine replace­ment, but among other things it reached 2,890km/h (l,796mph, Mach 2.72), climbed to 20km (65,617ft) in 5min 5 sec, and reached a sustained altitude of23,250m (76,280ft).

Ye-152A

This was essentially an interceptor version of the Ye-150, but with the important difference that it was powered by a pair of mature R-l 1F – 300 (early MiG-21 type) engines, with a com­bined maximum thrust of 11,480kg (25,309 Ib). The airframe was designed to a load factor of 7, and 4,400 litres (968 Imperial gallons) of fuel was provided in six fuselage and two wing tanks, and provision was made for a centreline drop tank. The Ye-152A was designed for al­most automatic interceptions, guided by the Uragan-5 ground-control system and its AP-39 autopilot, finally locking on its own T sP-1 radar and firing the two MiG-developed K-9-155 mis­siles carried on down-sloping underwing py­lons. This fine aircraft was first flown by Mosolov on 1 Oth July 1959 (more than a year before the Ye-150) and it reached 2,135km/h (l,327mph, Mach 2.01) at 13,700m (44,950ft). It caused a sensation when it made a flypast at the 1961 Tushino airshow, being identified by Western experts as the (MiG-23′ because that was the next odd number after the MiG-21. After a busy career it crashed in 1965.

Ye-152

This was intended to be the definitive heavy interceptor, combining the R-l5-300 engine (uprated to 10,210kg, 22,509 Ib) with the air­frame and weapons of the Ye-152A. Two were built, Ye-152/1 and Ye-152/2. Apart from hav­ing a large single engine the obvious new fea­ture was that the Ye-152/1 carried its K-9 missiles on down-sloping launch shoes on the wingtips. Internal fuel was slightly increased, and avionics were augmented. From its first flight on 21st April 1961 it was plagued by en­gine problems, but eventually set a 100km closed-circuit record at 2,401km/h (1,492 mph, Mach 2.26), a straight-line record at 2,681km/h (l,666mph, Mach 2.52) and a sus­tained-height record at 22,670m (74,377ft). These were submitted to the FAI as having been set by the ‘Ye-166’. In fact both Mosolov and Ostapenko achieved 3,030km/h (1,883 mph, Mach 2.85). The Ye-152/2 was intended to have the Smerch (whirlwind) radar and as­sociated Volkov K-80 missiles, but this was never incorporated. It first flew on 21st Sep­tember 1961, and after a brief factory test pro­gramme was rebuilt into the Ye-152P.

 

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.

Sukhoi S-22I

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.

Span (63°)

10.03m

32 ft 10% in

(30°)

13.68m

44ftl03/4in

Length overall

1 9.03 m

62 ft 5!4 in

Wing area (63°)

34.45m2

370.8ft2

(30°)

38.49m2

414.3ft2

Dimensions

Подпись: Weights Empty 9,480kg 20,899 Ib No further data, but abundant data exists for production successors. Sukhoi S-22I

Two views of the S-22I.

Sukhoi S-22I

 

Yakovlev Experimental Piston Eiigiiied Fighters

Yakovlev Experimental Piston Eiigiiied Fighters

Yakovlev Experimental Piston Eiigiiied Fighters

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.

Yakovlev Experimental Piston Eiigiiied Fighters

Photograph on the opposite page: Yak-7GK.

Yakovlev Experimental Piston Eiigiiied FightersThis page, above and below: Two views of UTI-26PVRD.

Yakovlev Experimental Piston Eiigiiied Fighters

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.