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Yakovlev Yak 2 & Yak 4

During World War II, the Yakovlev Yak-2 emerged as a Soviet light bomber/reconnaissance aircraft with limited range.

Despite its production in small quantities, the majority of these aircraft were unfortunately obliterated in the initial phases of Operation Barbarossa.

The Yak-2, originally designated as the Ya-22 in the Yakovlev OKB numbering system, underwent a redesignation in 1941 and became known as the Yak-2.

This aircraft featured a combination of materials in its construction, with wooden wings and centre fuselage, a duralumin forward fuselage, and a rear fuselage constructed with steel tube framing, topped with a wooden upper decking and fabric skin.

The cockpit was situated at the very tip of the nose, while the navigator/gunner occupied a compartment located behind the trailing edge of the wing.

In its initial form, the prototype lacked armament, bomb shackles, a radio, and navigational equipment.

However, despite these omissions, it held the distinction of being the fastest multi-engined aircraft in the Soviet Union, capable of reaching speeds of up to 567 km/h (352 mph) at an altitude of 9,900 m (32,500 ft).

This impressive speed was largely attributed to the absence of heavy military equipment on board.

Stalin issued an order for the BB-22 (a short-range bomber) to be put into production on 15 March 1939, without waiting for its evaluation by the NII VVS (Air Force Scientific Test Institute).

The evaluation, which took place in the early summer, revealed several issues with the aircraft.

The tests found that the engine cooling systems were insufficient, the brakes were problematic, and the fuel system was unreliable.

Converting the aircraft into a bomber posed a significant challenge, requiring the redesign of the centre fuselage to accommodate the gunner/navigator position just behind the pilot.

Additionally, two 7.62-millimeter (0.3 in) ShKAS machine guns were installed, with one for the gunner and the other fixed in the nose.

To facilitate the use of the rear gun, the rear decking of the fuselage was designed to pivot downwards.

Factory No. 1 successfully manufactured the initial pre-production BB-22 in December 1939, however, its maiden flight was not accomplished until the subsequent February.

The aircraft underwent service evaluation in the period of March to April 1940, revealing disappointing results.

Despite a reduction in fuel from 1,000 kg (2,200 lb) to 600 kg (1,300 lb), the gross weight of the aircraft had increased by 357 kg (787 lb).

Additionally, the maximum speed had regressed to 515 km/h (320 mph) at an altitude of 5,000 m (16,000 ft).

The engine cooling system remained unsatisfactory, and the undercarriage was deemed too fragile.

Furthermore, both longitudinal and lateral stability were found to be unsatisfactory, rendering the aircraft suitable only for highly skilled pilots.

The comprehensive test program report concluded that the aircraft lacked combat capability and reliability, and flights with a 400-kilogram (880 lb) bomb load could potentially endanger the crew.

In order to improve the Yak-2 aircraft, a remediation program was initiated which involved replacing the single-wheel main landing gear with two-wheeled units and reducing the height of the fuselage upper decking.

During this time, Factory No. 1 stopped production while Factory No. 81 in Moscow continued to manufacture the aircraft.

The Yak-2s produced by Factory No. 81 were of superior quality due to better surface finish and more closely fitted engine cowlings and doors, which minimized drag and increased the aircraft’s speed by 10-20 km/h (6.2-12.4 mph).

Further development work led to the creation of the Yak-4, which was equipped with Klimov M-105 engines.

Ultimately, a total of 201 Yak-2s were built before production was halted in April 1941.
Variants
Ya-22
Prototype.
BB-22
Initial production with flush rear canopy
Yak-2
(VVS designation used in service of izdeliye 70 / BB-22 2M-103)

Two-seat light bomber/reconnaissance aircraft.
BPB-22
(PB-22 2M-105, BB-22PB)

Prototype short-range dive bomber.
Yak-2KABB
Prototype ground-attack aircraft fitted with the KABB-MV gun/bombing installation (KABB-MV – combined gun/bomb battery), composed of a ventral cannon pack and a special glazed nose for bomb aiming equipment.
R-12
Prototype photographic reconnaissance aircraft.
I-29 / BB-22 IS
Experimental long-range fighter aircraft.
Yak-2bis / BB-22bis / izdeliye 70bis)
Prototype of the Yak-4 2M-105
Yak-4
Soviet light bomber.
The Yak-4 aircraft was an upgraded version of the Yak-2 model, which aimed to address the issues encountered with the latter.
The Yak-4 was equipped with more powerful Klimov M-105 engines and underwent several modifications, including the addition of two extra fuel tanks in the outer wings, increasing the total fuel capacity to 180 litres (40 imp gal; 48 US gal).
The gunner’s canopy was also redesigned to provide more space for the operator to use the 7.62 mm (0.300 in) ShKAS machine gun.
The upper fuselage was restructured to enhance the gunner’s field of fire, and the oil coolers were relocated from the sides of the engine nacelles to the ‘chin’ position to improve their performance.
Specifications
Yak-2
Crew
3
Length
9.34 m (30 ft 8 in)
Wingspan
14 m (45 ft 11 in)
Wing area
29.4 m2 (316 sq ft)
Empty weight
4,043 kg (8,913 lb)
Gross weight
5,380 kg (11,861 lb)
Powerplant
2 × Klimov M-103 V-12 liquid-cooled piston engines,
716 kW (960 hp) each
Propellers
3-bladed constant-speed propellers
Performance
Maximum speed
515 km/h (320 mph, 278 kn) at 5,200 m (17,060 ft)
Range
800 km (500 mi, 430 nmi)
Service ceiling
8,900 m (29,200 ft)
Time to altitude
7.7 minutes to 5,000 m (16,404 ft)
Wing loading
183 kg/m2 (37 lb/sq ft)
Power/mass
0.27 kW/kg (0.16 hp/lb)
Take-off run
500 m (1,640 ft)
Landing run
500 m (1,640 ft)
Armament
2 × 7.62 mm ShKAS machine guns
Up to 600 kg (1,300 lb) of bombs
Sources
Yakovlev Aircraft Since 1924 – Bill Gunston & Yefim Gordon.
OKB Yakovlev, A History of the Design Bureau and its Aircraft-Yefim Gordon, Dmitriy Komissarov & Sergey Komissarov.
Soviet Aircrafts Illustrated-A.S.Yakovlev.
The History of Soviet Aircraft from 1918-Vaclav Nemecek.
Soviet AF Fighter Colours 1941-45-Erik Pilaeskii.
Soviet Combat Aircraft of the Second World War, Vol 1, Single Engined Fighters-Yefim Gordon and Dmitri Khazanov.
Early Soviet Jet Fighters, The1940s and early 50s-Yefim Gordon.
Soviet Secret Projects, Fighters Since 1945-Tony Buttler & Yefim Gordon.
Soviet Secret Projects, Bombers Since 1945-Tony Buttler & Yefim Gordon.
Soviet Aircraft of Today-Nico Sgariato.
Modern Soviet Fighters-Mike Spick.

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