Soviet Zveno Aviamatka

Zveno (Russian: Звено, a military unit "Flight") was a parasite aircraft developed in the Soviet Union during the 1930s. It consisted of a Tupolev TB-1 or a Tupolev TB-3 heavy bomber mothership and two to five fighters. Depending on the variant, the fighters either launched with the mothership or docked in flight, and they could refuel from the bomber. The definitive Zveno-SPB using a TB-3 and two Polikarpov I-16s, each armed with two 250 kg (550 lb) bombs, was used operationally with good results against targets in Romania during the opening stages of the German-Soviet War. The same squadron later carried out an attack against a bridge on the River Dnieper that had been captured by German forces.

In all Zveno configurations, all aircraft were piloted and all had their engines running — it was expected that the combined thrust would more than offset the weight and actually improve the performance of the mothership compared to conventional bombers. The fighters were rigidly attached via pyramid-shaped metal frames, with both latches controlled by the fighter pilots. (On Zveno-1, the front latches were controlled by the bomber crew, while the back latch was controlled by the pilot; this was changed to all-pilot control in the next version). The original design included umbilical fuel lines which permitted the fighters to use fuel from the bomber while attached, although this was not fully implemented in practice.


Configurations

Zveno-1- Tupolev TB-1 and two Tupolev I-4 on top of the wings. The normally sesquiplane I-4s had the bottom wings removed (with no ill effect on flight characteristics) due to clearance problems with TB-1 propellers.

Zveno-1a- TB-1 and two Polikarpov I-5 on the wings.

Zveno-2- Tupolev TB-3 and three I-5, the third aircraft was attached over the fuselage. 

Zveno-3- TB-3 and two Grigorovich I-Z under the wings.

Zveno-5- TB-3 and a single I-Z under the fuselage which attached and detached in the air as there was not enough ground clearance for the fighter. 

Zveno-6- TB-3 and two Polikarpov I-16 which were attached on the ground with the landing gear retracted. 

Zveno-7- TB-3 and two I-16s, all docked in the air. 

Aviamatka (Airborne mothership)- TB-3 with two I-16s under the wings, two I-5s on top of the wings, and one I-Z attached under the fuselage in mid-air. 

 Vakhmistrov also worked on a larger Aviamatka with eight I-16s. In this scheme, the TB-3 would get airborne with two I-16s under the wings and the remaining six would attach in the air. Not all eight would attach at one time, but would rotate in and out during the flight, detaching and re-attaching as needed. These six aircraft could also refuel from the mothership. Although a few successful mid-air dockings and fuel transfers were performed in 1938 (Zveno 6 and 7), the eight-fighter configuration was never completed.

SPB (Sostavnoi Pikiruyuschiy Bombardirovschik - Combined Dive Bomber)- TB-3 and two I-16s under the wings, each armed with a pair of 550 lb FAB-250 bombs. Used operationally in World War II with good success.

Tupolev TB-3

The Tupolev TB-3 (Russian: Тяжёлый Бомбардировщик, Tyazhyolyy Bombardirovshchik, Heavy Bomber, civilian designation ANT-6) was a monoplane heavy bomber deployed by the Soviet Air Force in the 1930s and used during the early years of World War II. It was the world's first cantilever wing four-engine heavy bomber.  Despite obsolescence and being officially withdrawn from service in 1939, the TB-3 performed bomber and transport duties throughout much of World War II. The TB-3 also saw combat as a Zveno project fighter mothership and as a light tank transport.

The TB-3 was used operationally during the Battle of Khalkhin Gol against Japan and in the Winter War with Finland. Although it was officially withdrawn from service in 1939, at the start of the Great Patriotic War on 22 June 1941, the Soviet Air Force had 516 operational TB-3s, with an additional 25 operated by the Soviet Navy.[11] Stationed far from the USSR's western border, the ТB-3s avoided catastrophic losses during the first German air strikes, after which TB-3s from 3rd TBAP (Heavy Bomber Regiment) began flying night bombing missions on 23 June. A shortage of combat-ready aircraft also required daytime use of TB-3s without fighter escort and in this role the bombers, operating at low-to-medium altitudes, suffered heavy losses to enemy fighters and ground fire. By August 1941, TB-3s made up 25% of the Soviet bomber force and, operated by elite air force crews, were flying up to three combat missions per night.[11] The aircraft participated in all major battles through 1943, including the first Battle of Smolensk, the Battle of Moscow, the Battle of Stalingrad, the Siege of Leningrad, and the Battle of Kursk. On 1 July 1945, 18th Air Army still had ten TB-3s on the active roster.

The TB-3 served extensively as a cargo and paratroop transport, carrying up to 35 soldiers in the latter role. In the first five months of the war, the aircraft transported 2,797 t (6,166,000 lb) of cargo and 2,300 personnel.

The TB-3 was also used in several special projects as a fighter mothership in the Zveno project and for delivering light T-27, T-37, and T-38 tanks. On 1 August 1941, a pair of TB-3s in Zveno-SPB configuration, each with two Polikarpov I-16 fighters carrying a pair of 250 kg (550 lb) bombs, destroyed an oil depot with no losses in the port of Constanța, Romania. On 11 and 13 August 1941, Zveno-SPB successfully damaged the King Carol I Bridge over the Danube in Romania. Zveno operations ended in the autumn of 1942 due to the vulnerability of the motherships.

Polikarpov I-16

The Polikarpov I-16 (Russian: Поликарпов И-16) is a Soviet single-engine single-seat fighter aircraft of revolutionary design; it was the world's first low-wing cantilever monoplane fighter with retractable landing gear to attain operational status and as such "introduced a new vogue in fighter design".[2] The I-16 was introduced in the mid-1930s and formed the backbone of the Soviet Air Force at the beginning of World War II. The diminutive fighter, nicknamed "Ishak" or "Ishachok" ("donkey" or "burro") by Soviet pilots, figured prominently in the Second Sino-Japanese War,[3] the Battle of Khalkhin Gol,[3] Winter War and the Spanish Civil War[4][5] – where it was called the Rata ("rat") by the Nationalists or Mosca ("fly") by the Republicans.

Polikarpov I-5

The Polikarpov I-5 was a single-seat biplane which became the primary Soviet fighter between its introduction in 1931 through 1936, after which it became the standard advanced trainer. Following Operation Barbarossa, which destroyed much of the Soviet Air Forces (VVS), surviving I-5s were equipped with four machine guns and bomb racks and pressed into service as light ground-attack aircraft and night bombers in 1941. They were retired in early 1942 as Soviet aircraft production began to recover and modern ground-attack aircraft like the Ilyushin Il-2 became available. A total of 803 built (including 3 prototypes).

Grigorovich I-Z

The Grigorovich I-Z was a fighter aircraft developed in the Soviet Union during the 1930s. Advances in aircraft survivability thanks to all-metal construction and self-sealing and inert gas-filled fuel tanks led to experimentation with large-caliber weapons to shoot them down. In Soviet Union, Leonid Kurchevsky developed a series of recoilless rifles in various calibers and in 1930 was decided to adapt the 76.2 mm (3 in) weapons for aircraft use.[1]

The result was a conventional strut-braced monoplane with fixed landing gear. A pair of Kurchevsky APK (APK - Aviatsionnaya Pushka Kurchevsky - aircraft cannon Kurchevsky) rifles were mounted under the wings outside the propeller arc and the rear fuselage and tail assembly were of reinforced metal construction to withstand the blast. A single small-caliber synchronized machine gun in the left fuselage was added to aid the pilot in aiming.[1]

Two prototypes were built, the first flying in mid-1931. The second strengthened I-Zbis flew at the beginning of the following year. These were followed by 21 examples ordered as evaluation aircraft and 50 production machines. By the time this last batch was being delivered, however, it was already apparent that the concept of a "single-shot" fighter was flawed and the I-Zs that had been built were relegated to various testing roles. One such role was as a parasite fighter in the Zveno project.