Jakovlev BB-22 / Jak-4

the History of the bombers As 2 and As-4.[/heading]

And. With. Yakovlev and his design team (OKB-115), for this case driven by an engineer Jevgeniem Gergievičem Adler, tried since 1938 to build a fast twin-engine aircraft, whose basic manufacturing raw material would have been non-deficit material – wood, then the plywood of the siberian pine and birch wood. The designers have tried to maximise the aerodynamic cleanliness of the proposed aircraft, the fuselage was created from the tube and its front part was covered by aluminum panels, the rear part was covered with canvas. The construction of the middle part of the fuselage and the wings were wooden, the wing was in one piece. Initially it was calculated with a wing with larger span, And. With. Yakovlev had experience with sports and to increase speed diminished margin of the wing. The powertrain the Klimov M-103 were just kapotované and radiator fluid and oil were in the rear of the engine nacelles, which is where they minimize their aerodynamic resistance. The engines geared up two-step propeller you KNOW-2, you were on the other planes mistaken for infinitely adjustable propeller you KNOW-22A. The surface of the aeroplane was polished and all the inequalities of the surface were carefully removed. A new machine called the Ja-22 or "flight 22" (самолет 22), or No.22 was completed in February 1939.

Factory tests may have shown that has the plane's considerable speed potential, but used engines M-103 will greatly overheat, engine oil is literally napékal on the inner walls of the engine. Thanks to this overheating of the engines it was not possible to achieve the calculated performance, e.g., according to the original calculations of the expected output to the height of 7,000 m for 8 minutes and 40 seconds, the reality was quite different – 35 minutes of climb it was necessary to interrupt and during horizontal flight, to cool the oil in the engine. Another problem was the small size of the bogie wheels and undersized brakes, brake linings to burn out in 3-4 flights. Other problems were in the fuel system, there is still the danger of the fire of the aeroplane. The prototype of the Ja-22 has yet flown without weapons, but it was calculated with the armament of two machine guns ŠKAS the caliber of 7.62 mm. And. With. Yakovlev thought about the introduction of this machine into production and on its deployment as a fast reconnaissance aircraft with short-range.

For the first time, he was brought the leaders of the soviet state and to the public at the may day parade over Red square, when at the conclusion of the show flew over the main stage, a red twin-engine plane with a silver wing. Flew was very spectacular, because it was executed at least twice the speed than what's been reported the preceding aircraft. J. In. Stalin had to report on this fast airplane, and when he learned that it is the work of his favourite designer started at Yakovlev urge to open your machine to the state examination. The launch was slightly delayed, because of the prototype while landing broke the undercarriage leg and in addition was damaged and not fixed wing.

State examinations have been started 29. may, 1939, and confirmed it, what was the engineers previously known, overheating of motors, undersized chassis, leaky and not very reliable hydraulics, the impossibility of mutual communication of the two members of the crew, etc. Yakovlev, however, behaved most predictably, when already in march left it at specialized design office no. 70 to repaint the complete drawing documentation, it took until the end of April, but on the basis of this drawing documentation can be initiated mass production almost immediately.

The first aircraft was completed as a reconnaissance machine, whose main defense should be the speed. The aircraft was marked R-12, got the armament of two machine guns ŠKAS, one was firm, controlled by the pilot to fire forward and the other machine gun was moving, for the defense of the rear side, its barrel field, however, was considerably limited, however, this was not considered a big lack, because attacks from behind not practically occur (thanks to the great speed) and the machine gun had a rather symbolic significance, dominated to the observer, which dominated even the camera AFA-13 or AFA-19 (the springs here do not match).

The second version was supposed to be a heavy fighter -29, which was completed in a single copy, it was powered by powerful engines Klimov M-105, most likely in the version of the Klimov M-105R - performance was the same as M-105P, different was the gear ratio of the reducer. The armament was formed by a pair of fixed cannons ŠVAK the caliber of 20 mm, each with a stock of 300 shells. The question is whether the aircraft was a single-seater or two-seater (here again the strands diverge). At first he had a fighter type of big priority, but that gradually declined and declined, until he was preferred Petljakow Pe-3 and the whole thing a fighter I-29 was in 1942 terminated. It is true that Yakovlev and his design team has been busy single-digit fighter jet As-1 and training aircraft Yak-7UTI and so the project I-29 didn't have one "take".

J. In. Stalin insisted on the speedy introduction of the latest type series - a fast light bomber with short-range labeled as BB-22 (ближний бомбардировщик ББ-22), it was the so-called special-purpose designation. At the turn of the years 1940/1941 were converted to How to-2, this designation should be highlighted the name of the chief designer. Jakovlevovo OKB in their original imagination, it was envisaged that in the bomber version to carry aircraft maximum 350 kg of bombs. It is army seemed too little and demanded that the aircraft carrying 400 to 600 kg of bombs. Yes, 350 kg of bombs is actually little, but the original aircraft was designed as speed, highly aerodynamic aircraft and that what he now wanted the leaders of the army and Stalin, was it, what definitely designed not.

Due to the fact that And. With. Yakovlev had already done documentation for the production of the finished, has been ramping up production fairly quick, but definitely not simple and easy. The first BB-22 has been completed 31. December 1939 and [he was 20. February 1940. The main change was to move the shooting post, the original with limited space for shooting disappeared and a new toilet was just behind the pilot, this change places at the same time removed the problem with the communications crew. After the tests of this aircraft, it was necessary to make several major adjustments, the bomb bay had to be enlarged and moved up for the second wing spar. Shooter / observer after the performed adjustments to the sat in polovysunovatelné gun turret MV-3. The disadvantage was that just a slide of a turret, about eighty millimeters of increased aerodynamic drag enough that there has been a noticeable loss of speed. Another source of resistance of the air were two cougars FAB-100, that have been, or more correctly - should be hung on external hinges, into the bomb bay, it was possible to hang up only 400 kg of bombs. Speed with full suicide the load decreased to the level of 478 km/h. Next, nemenším problem was still unresolved overheating engines M-103, the designers are given a problem they tried to solve the larger radiator, but the result was a further drop in speed of 15 km/h, subsequently decreased range of 630 km, the reliability of the engines, however, continue to failed to improve. Managed to increase the weight of the bombs, the last of the machine Jake-2 could carry 600 kg of bombs, the Weight of the aircraft increased and when I mention higher take-off weight, I have to mention another adjustment, the original undersized chassis was duplicated, to the engine nacelles was called upon (now not quite) double chassis with wheels next to each other.
In production next to the moscow plant no. 1 from the summer of 1940 involved the race no 81 in Tušinu, produced here BB-22 have more problems with the workshop performing and so an uneven surface logging more kilometers of the maximum speed. A few dozen aircraft cost nepřevzato the soviet army, the total was in both the factories made 111 aircraft BB-22 / As-2.

In march 1940 they started the designers and technicians to work on more dramatically improved the aircraft, identified as BB-22bis, the most important improvement was the installation of more powerful engines the Klimov M-105, more powerful engines, it was necessary to cool more effectively than older M-103, therefore, the oil radiator moved under the engine and at their relaxed place were installed the radiator fluid. While this increased resistance, but the engines M-105 have been cooled at least to the same extent, as the older M-103. New engines however, the next higher power have brought with them higher fuel consumption, therefore, it was possible a new Yak-4 podvěsit a pair of auxiliary fuel tanks, each having a volume of about 100 liters, these tanks, however, again zvýšovaly take-off weight and aerodynamic resistance, range but rose to 1 100 km. No less important change was the installation of a propeller type, you KNOW-22E, these propellers were in flight infinitely adjustable, and thanks to that slightly decreased fuel consumption. Prototypes of the bomber BB-22bis were once again powerful, but the serial machines As-4 once again the performance lost, because they once again increased their weight. How-4 got into a circle from which there was no way out, the performance of the engines to cover the increase in the weight and performance too have not increased and the new engines did not exhibit much higher reliability and still přehřívaly.

In November 1940 it was the engineers submitted 12 nejzávadnějších deficiencies, considered to be military pilots on aircraft BB-22bis, these defects should be promptly removed. Actually managed to most of these shortcomings remove, e.g., lack of longitudinal stability has been removed by extending the fuselage about 230 mm (the prototype of the BB-22bis to happen already in June or July 1940), but the race in Tušinu this change into production at all did not load. In December 1940 there was a change in the designation of the aircraft and bombers BB-22 (with engines M-103) became Both-2 and BB-22bis (engines M-105) was converted to As-4. The end of the year started a state examination, which, however, didn't go for the new version too successfully, tested letounoum was constantly reproached for the little reliability of the engines and the performances did not meet expectations.

The discontent of the combat units with these machines was considerable, and in addition appeared the aircraft designer . M. Petljakova PB-100, Yak-2 and Yak-4 easy to their performances surpassed in all respects. A completely unsatisfactory can mark the quality of production, to 31. January 1941 made tušinský race 50 yak-4 and of this number were flying only three!!!
Orders for large series have been phased out and production was ultimately terminated on the basis of the decision of the government of the day 13. February 1941, after this date it was completed few aircraft How-4.

Let's go back now to 21. June 1940, then received OKB-115 task – to build on the basis of the BB-22 dive bomber, the aircraft designated as the BPB-22 (ближний пикирующий бомбардировщик), got on the wings of the tilting surfaces of the steel plates – thus the aerodynamic brake, which could reduce the speed of the dive, in October the tests were terminated after the crash, caused by the stoppage of both engines, the tests were not completed.

In march until April 1941 it was tested attack aircraft designated as Yak-4 KABB-MV. The main distinguishing feature was the glazed prow of the aircraft, thanks to it it was possible to focus on-board weapons (2x cannon ŠVAK and 2x machine gun ŠKAS), weapons can be bend down 30° down, in the bomb bay were containers with 8-20 kg bombs. The aircraft performed a total of 10 flights and was subsequently scrapped. The letters M and V refer to your creator – Možarskij and Venevodov.

After the robbery of the USSR pilots, bombers, Yaks, if the technical condition of their aircraft allowed, taking off against the with the enemy, to attack the advancing column of troops and on the German tanks. However, losses were great, many Yaks are also received into the hands of the Germans completely unspoiled (mostly grounded due to malfunctioning engines), it happened thanks to the rapid penetration of the German troops and the subsequent cast of airports.

The russians subsequently their Yak-2/4 fast downloading from the combat troops, the aircraft were then deployed, such as transport, courier, fasteners and postal aircraft.

Airport staff machines As-2 and As-4 should not in popularity for their challenging maintenance and servicing, at airports with nezpevněným the surface of the floundering round and the operation was greatly restricted. Pilots don't like them for their rather demanding operation (in particular, control of the engines and propellers, he said it was quite difficult).


sources:
Bill Gunston and Yefim Gordon, Yakovlev Aircraft since 1924, Brasseys Publications, First Edition edition, 1997, ISBN: 0-85177-872-0
B. L. Simakov, Samolety party Sovětov, DOSAF of the USSR, 1974.
L+K no 23 / 1977, str. 913, Aircraft 39-45, Yakovlev BB-22, Václav Němeček
L+K no 23 / 1988, str. 28/908, Aircraft 39-45, Yakovlev R-12/I-29, Václav Němeček
http://www.airpages.ru/ru/yak2.shtml
http://www.airwar.ru/enc/fww2/i29.html
http://www.airwar.ru/enc/aww2/yak2kabb.html
http://www.airwar.ru/enc/spyww2/r12.html
http://aviarmor.net/aww2/aircraft/ussr/yak-2.htm
http://www.ctrl-c.liu.se/misc/ram/ya-22.html
http://hobbyport.ru/avia/bb_22.htm
www.fido.sakhalin.ru
http://base13.glasnet.ru/text/yak2-1.htm
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