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| Production Yak-4. |
by Paul Roland
In 1938 a design collective headed by A. S. Yakovlev completed work on the streamlined BB-22 two-seat aircraft. It was their first twin-engined aircraft originally intended for a high-speed high-altitude reconnaissance role but then it was decided to also use this aircraft for short-range bombing missions. In the spring of 1939 the BB-22 made its first flight and it was immediately accepted into Soviet Air Force use.
The BB-22 was of mixed construction. The two longeron scheme wing was wooden with a veneer covering and was built onto the fuselage center section. The forward fuselage and pilot’s cabin with sliding canopy was duralumin pipe with a covering of plywood and the tail boom section with the observer’s cabin situated low in the middle of its front was chrome pipe with a linen covering. The horizontal tail and fins were wooden. The ailerons and tail unit flaps were duralumin with a linen covering. The tail unit was enlarged so as to increase the aircraft’s useful range by the addition of a half-sphere at the rear of each rudder.
This aircraft was capable of short takeoff since the weight was about 5 tons. There were two M-103 engines of 960 horsepower which provided a maximum flight speed of 567 kilometers per hour which was more than that of any fighter or two-engined aircraft of that time. It was almost 150 kilometers per hour faster than the twin engine SB (ANT-40) bomber. Beneath each engine nacelle was a pair of landing gear doors, made of duralumin, which opened to an angle of 50 degrees. The undercarriage was a retractable three-wheel scheme. In winter time use the wheels were replaced by skis.
Control of the rigid rudder for altitude and the ailerons were operated by means of a handle located in the pilot’s cabin. The rudder was controlled by means of wires. The landing gear doors opened and closed by means of the same powered gears as the undercarriage. The undercarriage was hydraulically controlled with an electro-drive pump but this system could accidentally be opened by hand. Braking of the main wheels was pneumatic.
The fuel feed system for the engines was from six tanks: two in the fuselage behind the observer’s cabin and there were two in each wing between the longerons. The tanks, pipes and fittings were made of duralumin.
Each engine nacelle had an oil radiator located beneath the motor. At the rear of each motor was a water radiator for cooling which surrounded the motor’s cylinders. The cooling air passed around the motor by means of lateral slits and tunnels. This air exhaust was regulated at the rear of the nacelle by means of hydraulically-activated louvers. Each nacelle also contained a carbon dioxide fire prevention system.
For defense against attacking aircraft a machine gun was installed in the nose in addition to the rear cabin’s dorsal machine gun but the cumbersome protective screening increased the aircraft’s weight. (It was later discovered that these guns were not sufficient as armament.) The nose mounted gun was also to be used for ground attack purposes. To prepare the dorsal machine gun for firing the observer had to remove his canopy and the fabric-covered upper part of the fuselage—that part from his canopy to the horizontal tail structure—had to be lowered into the fuselage tail boom’s lower part. The 400 kilograms load of four to eight bombs and its suspension system also increased the take-off weight.
An unarmed transport or cargo version, also used for liaison duties, of the BB-22 was flown but its performance was not satisfactory.
A modification of the reconnaissance/ bomber/attack aircraft’s cabin area into a large bulged “greenhouse” and deletion of the forward machine gun (one report says that this gun was retained with another machine gun mounted beside it), to improve aerodynamics and to decrease the loaded weight, in 1941 resulted in an aircraft bearing the new appellation of Yak-4. Each single main wheel was replaced by a two-wheel assembly, partially retractable, to support the strengthened airframe with new M-105 engines. Supplementary equipment, including underwing bombs and dive brakes, produced rather poor flying characteristics in the Yak-4.
This aircraft entered service in 1941 but in the following year the Yak-4 was found to be fulfilling a ground attack role for which it was not suitably armored and there were other newer light bombers. Therefore, after six hundred aircraft of the BB-22/Yak-4 series was manufactured since 1940, it was delegated to high-altitude reconnaissance and it was replaced in the fighter-bomber role by the more powerful, constructed of duralumin, Pe-2 dive bomber.
BB-22
Year of first flight: 1939
Length: 10.17 meters
Wingspan: 14 meters
Wing area: 32 square meters
Crew: Two
Take-off weight: 5,200 kilograms
Armament: Two ShKAS 7.62mm machine guns
Bomb load: 400 kilograms
Powerplants: Two Klimov M-103 liquid-cooled in-line
Power: 960 horsepower
Maximum speed: 567 kilometers per hour
Range with bomb load: 800 kilometers
Range without bomb load: 1,600 kilometers
Service ceiling: 8,800 meters
Yak-4
Role: Light bomber
Manufacturer: Yakovlev
Designer: Alexander Sergeyevich Yakovlev
First flight: 20 February 1940
Introduction: 1941
Retired: 1945
Primary user: VVS
Number built: 90
Developed from: Yakovlev Yak-2
Length: 10.17 meters
Wingspan: 14 meters
Wing area: 32 square meters
Crew: Two
Take-off weight: 5,200 kilograms or 5,845 kilograms
Armament: One or three ShKAS 7.62mm machine guns
Bomb load: 400 kilograms (minimum); 600 kilograms (maximum)
Powerplants: Two Klimov M-105 liquid-cooled in-line
Power: 1,100 horsepower
Maximum speed: 574 kilometers per hour
Speed at 5,000 meters: 540 kilometers per hour
Range with bomb load: 800 kilometers
Range without bomb load: 1,600 kilometers
Maximum altitude: 11,000 meters
Author’s Note
No clear definition is made between the BB-22, Yak-2 and Yak-4 in any book used by this author for reference. Therefore, the author assumes the following to be correct:
The BB-22 was the manufacturer’s designation of the Yak-2 “prototype.” The Yak-22 underwent cabin, airframe, bomb carrying, etc., modifications so as to become the Yak-4.
Any photo showing a military aircraft bearing Soviet markings which is captioned as an aircraft of the Red Air Force either shows an aircraft used by the nation of the Soviet Union or the photo caption is incorrect. The Soviet Army may be called the Red Army (even the Soviet press uses that title) but the USSR’s military aeronautical fleet is—and must be—referred to as the Soviet Air Force.
Publisher’s Note
According to Russian Aircraft Since 1940 by Jean Alexander (Putnam & Co., Ltd., London, 1975), this aircraft was A. S. Yakovlev’s first military design. It was designated the Ya-22 (the manufacturer’s designation was AIR-22). It was completed in early 1939. Initial tests were so successful that it was put into production immediately as the BB-22 (Blizhnyi Bombardirovshchik = short-range bomber) although it had been originally designed as a long-range fighter-reconnaissance aircraft with the designations I-29 for the fighter version and R-12 for the reconnaissance version. It later received the designation Yak-4.
Bibliography
Kondratbev, V. Modellist Konstruktor. [Soviet magazine] Moscow, 1976.
Nemecek, Vaclav. Sovetska Letadla. Nase Vojsko, Prague, 1969.
Nowarra, Heinz J. Die Sowjetischen Flugzeuge 1941-1966. J. F. Lehmanns Verlag, Munich, 1967.
Nowarra, Heinz J. and G. R. Duval. Russian Civil and Military Aircraft 1884-1969. Fountain Press Ltd., London, 1970.
Simakov, B. L., editor. Airplanes of the Land of the Soviets 1917-1970. Voluntary Society for Assisting Air Force, Army and Navy Publishing House, Moscow, 1974.
Taylor, John W.R., editor. Combat Aircraft of the World From 1909 to the Present. G. P. Putnam’s Sons, New York, 1969.
Yakovlev, A. S. Soviet Aircraft. Science Publishing House, Moscow, 1975.
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| Yakovlev Yak-4. |
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| The prototype BB-22. The fuselage and engine nacelles are red, the wings and tails are white with the rear of the rudder painted in the traditional A. S. Yakovlev red/white stripes. Each propeller was polished natural duralumin. However, the wartime operational Yak-4 bore the usual Soviet Air Force camouflage color scheme. |
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| A production Yak-4 in flight shows the similarity of the wing design to that of the Yak-1 fighter. |
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| The Yakovlev Yak-4 production version had glycol radiators in the rear of the nacelles and chin-type oil cooler intakes. The rear fuselage was fabric covered. |
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| Production Yakovlev Yak-4. |
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| Production Yakovlev Yak-4. |
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| Yakovlev Yak-4. |
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| The M-105 engine of the BB-22bis #1002 airplane. |
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| Experimental BB-22bis with M-105 engines. |
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| The first prototype, the Samolot 22. |
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| The first prototype, the Samolot 22. |
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| The first prototype’s engine, Samolot 22. |
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| BB-22. |
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| BB-22 with ski undercarriage. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Yak-4, early in Barbarossa campaign. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Production Yak-4. |
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| Yak-4 engine. |
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| Yak-4. The following information and three-view drawing (note split plan view) are courtesy of B.C.F. Klein. Type: Two-seat short-range light bomber and high-altitude reconnaissance aircraft. Powerplants: Two 1,100 hp M-501R in-line engines. Armament: Two fixed forward-firing 7.62 mm ShKAS machine guns in the nose and one flexible rearward-firing 7.62 mm ShKAS machine gun for the observer; plus eight 55 lb. bombs internally and four 220 pound bombs on wing racks. Maximum speed: 352 miles per hour. Wingspan: 45 feet 11 inches. Length: 33 feet 4.5 inches. |
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| Yakovlev Yak-4. |
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| BB-22 Drawings: This and the next three drawings are from Modellist Konstruktor magazine and show the aircraft in plan views, plus various detail views (propeller, cockpit and rear cabin views, undercarriage views, and landing flap mechanism), and sectional views of the fuselage. The drawings were prepared by V. Kondratbev from a restored BB-22. |
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| BB-22. Key to BB-22 Plan Drawings This is a list of the numbered parts on the drawings as translated by the author. 1. Air intake for oil radiator 2. Intake pipe for engine 3. Bar for rudder turning 4. Removable front fairing 5. Sliding portion of lighted pilot’s cabin 6. Eight 20 kg photo bombs 7. Aperture for hoist 8. Storage battery hatch 9. Strut of tail boom to fuselage 10. Engine exhaust pipe 11. Water radiator access 12. Landing flaps 13. Bending hinge plate for aileron 14. Control arm for aileron 15. Aileron rocker 16. Water radiator 17. Front of wing spar 18. Fuel tank 19. Rear of wing spar 20. Type of bending hinge plate for rudder elevation and depression 21. Oil tank 22. Aerial pressure receiver 23. Bomb bay 24. Navigation vision slit hatch (perhaps used for repair work) 25. Aileron section (gently closing panel) 26. Front fuselage strut 27. Cartridge box 28. Instrument panel for pilot 29. Front gunsight 30. Protective cushion for gunsight 31. KPA-36is oxygen apparatus 32. Control wheel for elevator elevation 33. Engine control lever 34. Control handle for retraction of undercarriage 35. Machine gun belt feed pipe 36. Control handle 37. Machine gun cartridge case outlet 38. Machine gun belt ejection outlet 39. ShKAS machine gun 40. Handle to recharge machine gun 41. Control handle for landing flaps 42. Oxygen tank 43. Left desk for pilot 44. Pilot’s cockpit floor (corrugated) 45. Steering handle for alignment of water radiator 46. Right desk for pilot 47. Instrument panel for navigator 48. Horizontal panel 49. AFA aerial camera 50. Navigator’s cockpit floor 51. Hammock seat 52. Power-driven bomb release gear 53. Cartridge case outlet 54. ShKAS turret machine gun 55. Fastening bracket for machine gun 56. Machine gun belt feed pipe 57. Hydraulic jacks for control of landing flaps 58. Synchronization bar 59. Guide roller 60. Guide 61. Cross bar 62. Joint 63. Lock for opened tail wheel position 64. Hydraulic jack for retracting tail landing gear 65. 300 x 125 mm wheel 66. Engine nacelle girder 67. Hydraulic jack for retracting main undercarriage arm 68. Brake hose 69. 600 x 250 mm wheel 70. Rearwards folding strut 71. Undercarriage door |
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| BB-22. |
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| BB-22. |
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| The first prototype. |
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| BB-22. |
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| BB-22bis. |
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| Production Yak-4. |
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| Production Yak-4. |
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