This project really caught my eye.
Name: The Zveno Project
Developed by: Soviet Union
Date Developed and Ended: 1930 - 1942
Bomber Aircraft Used: Tupolev TB-1, Tupolev TB-3
Parasite Fighter/Bomber Used: Tubolev I-4, Polikarpov I-5, Grigorovich I-Z, Polikarpov I-16
This project started in the 1930's it involved mounting "Parasite" Aircraft's on a Bomber aircraft, they were either mounted on top of the wing's or mounted below the wings, they also performed the first mid air docking. Though a request was made on the 16th of August 1941 for more AM-34FRN-engined TB-3s from the Air Force so that they could be converted into Zveno-SPB carriers, the request was denied by Stalin due to the the losses sustained by the Soviet Air force early on in the War. The limited action the Zveno Project saw was very successfull they were tasked in dive bombing certain facility's and a bridge, after roughly only 30 combat missions they were withdrawn from service in 1942, due to fears of the German Air Superiority and Aircraft.
Configuration's of the Zveno ProjectZveno-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. First flight 3 December 1931. The TB-1 was piloted by A. I. Zalevskiy and A. R. Sharapov, the I-4s were piloted by V. P. Chkalov and A. F. Anisimov. Vakhmistrov himself flew in the front gunner's turret.
Zveno-1a
TB-1 and two Polikarpov I-5 on of the wings, first flight September 1933. The TB-1 was piloted by Stefanovskiy, the I-5s were piloted by Kokkinaki and Grozd.
Zveno-2
Tupolev TB-3 and three I-5, the third aircraft was attached over the fuselage. First flight August 1934. The TB-3 was piloted by Zalevskiy, the I-5s were piloted by Altynov, Suprun, and Suzi.
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. On 23 March 1935, TB-3 piloted by Stefanovskiy and I-Z with Stepanchenok at the controls performed the world's first mid-air docking between two aircraft.
Zveno-6
TB-3 and two Polikarpov I-16 which were attached on the ground with the landing gear retracted. First flight August 1935, with the TB-3 piloted by Stefanovskiy, and the I-16s piloted by Budakov and Nikashin. I-16s could only detach, not re-attach, in flight.
Zveno-7
TB-3 and two I-16s, all docked in the air. First flight November 1939, pilots Stefanovskiy, Nyukhtikov, and Suprun. Fighters could re-attach in flight due to two retractable trapezes, one under each wing. Docking, while possible, was deemed too difficult to be practical.
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. First flight 20 November 1935. The TB-3 was piloted by Zalevskiy, the fighters piloted by Stefanovskiy, Nikashin, Altynov, Suprun, and Stepanchenok. 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 these being the Zveno 6 and 7, the eight-fighter configuration was never completed.
SPB (Sostavnoi Pikiruyuschiy Bombardirovschik - Combined Dive Bomber)
TB-3-4AM-34FRN and two I-16s under the wings, each armed with a pair of 250 kg (550 lb) FAB-250 bombs. Used operationally in World War II with good success.
Operational HistoryIn 1938, Vakhmistrov devised Zveno-SPB (SPB: Sostavnoi Pikiruyuschiy Bombardirovschik, Combined Dive Bomber) which consisted of a Tupolev TB-3-4AM-34FRN mothership and two Polikarpov I-16 Type 5 fighters. Each of the fighters was armed with a pair of 250 kg (550 lb) FAB-250 high-explosive bombs. Although an I-16 Type 5 could get airborne on its own with no more than 100 kg (220 lb) of bombs, once hoisted in the air by the TB-3 it could reach 410 km/h (220 knots, 255 mph) at 2500 m (8,200 ft), had a service ceiling of 6800 m (22,310 ft), and could dive at up to 650 km/h (350 knots, 405 mph). Once the bombs were dropped, the SPB-launched I-16s performed like conventional Type 5s. The three-aircraft Zveno-SPB had a total takeoff weight of 22000 kg (48,500 lb), a top speed of 268 km/h (145 knots, 165 mph), and a range of 2500 km (1,350 NM, 1,550 mi). The use of a mothership increased the range of the I-16s by 80%.
The SPB first flew in July 1937, with TB-3 piloted by Stefanovskiy, and I-16s piloted by Nikolayev and Taborovskiy. Following the successful test program in 1938, Zveno-SPB was accepted into service. By 1 February 1940, Soviet Air Force was supposed to receive 20 TB-3s and 40 I-16s, with the same number going to the Soviet Navy. Vakhmistrov was also asked to investigate the possibility of using Tupolev TB-7, Tupolev MTB-2, and GST (PBY Catalina) as the motherships, as well as arming I-16s with 500 kg (1,100 lb) bombs. By 1939, the government support for the project had waned, the Navy canceled all of its orders, and the Air Force reduced the number of fighters from 40 to 12. However, Soviet military observers noted the success of the Luftwaffe Junkers Ju 87 dive bombers in the opening stages of World War II. As the Soviet Union had no dive bombers, it was decided to resume low-scale work on the Zveno-SPB. Testing of the first production Zveno began in June 1940. It differed from the prototype in using the much more powerful I-16 Type 24 fighters. A total of six mothership-fighter combinations (six TB-3s and twelve modified I-16 Type 24s) were completed. All were attached to the 2nd Special Squadron of the 32nd IAP (Fighter Regiment) of the 62nd Aviation Brigade of the Black Sea Fleet Air Force stationed in Eupatoria. Mirroring the nickname of the Zveno experiments, the squadron was dubbed Shubikov's Circus (Цирк Шубикова) after its commander Arseniy Shubikov.
Zveno-SPB saw limited but successful combat use during the German-Soviet War. In the opening stages, the Black Sea Fleet Air Force was tasked with destroying industrial targets in Nazi Germany-allied Romania. The most important of these was the King Carol I Bridge over Danube which carried the Ploieşti-Constanţa oil pipeline. After several failed attempts to destroy the heavily protected bridge with conventional bombers, the task was given to the Zveno squadron. As a combat test, it was decided to first attack the Constanţa oil depot. On 26 July 1941, two Zveno-SPB aircraft performed a successful attack on the depot in broad daylight with no losses. The fighters disconnected 40 km (22 NM, 25 mi) from the target and returned to the home airfield under their own power.
The first of the two bridge raids took place on 10 August 1941. For this mission, the I-16s were fitted with additional 95-liter (25 US gal) underwing fuel tanks for an additional 35 minutes of flight time. Of the three Zveno-SPBs, one had to turn back due to mechanical problems. The other two launched their fighters 15 km (8 NM, 9 mi) from the Romanian coastline. The fighters successfully dive-bombed from the altitude of 1800 m (5,900 ft) and returned home with no losses despite heavy anti-aircraft fire. The second raid took place on 13 August 1941. This time, all three Zveno-SPBs reached the target. The six fighters scored five direct hits on the bridge and completely destroyed one of the spans. On the way back, the fighters strafed Romanian infantry near Sulina and returned to Eupatoria with no losses. Following the successful sorties, two additional Zveno-SPB were brought to operational status, bringing the total to five. The main limiting factor was the lack of high-output Mikulin AM-34FRN engines, as the other versions were not powerful enough to get the aircraft airborne. On 16 August 1941, Admiral Kuznetsov asked Joseph Stalin for additional AM-34FRN-engined TB-3s from the Air Force so they could be converted to Zveno-SPB carriers, but the request was denied as the Air Force had suffered heavy losses in the opening days of the war. In the meantime, the five aircraft continued flying operational sorties, destroying a dry dock in Constanţa on 17 August and a bridge across the Dnieper River on 28 August, losing one I-16 in the process. During the repeat attack the next day, four Zveno-launched I-16s engaged several Messerschmitt Bf 109s, shooting down two. Despite the high success rate, Zveno missions ended by 1942 due to high vulnerability of the obsolete TB-3s and I-16s in the face of enemy air superiority. It is estimated that Zveno-SPB flew at least 30 combat missions.
They come for our blood but drown in their own!