Myasishchev Molot - SDB
A report on the results of parametric studies in relation to a strategic aircraft (with "trans-polar range") was heard at a meeting of the TsAGI Scientific and Technical Council. Academician A. I. Makarevsky (chairman), prominent scientists (in the future academicians) S. A. Khristianovich, V.V.Struminsky, G. S. Byushgens and other specialists took part in the scientific and technical work. After a careful and detailed discussion of the reports of V.M. Myasishchev and G.N. Nazarov, the Aviaprom's leading institute decided on the possibility of real creation of a strategic bomber with the characteristics obtained as a result of a long study. From these works, in fact, the designing of the future “SDB” began according to the aphorism: “A dream is the beginning of embodiment”.
In accordance with the aviroject, which was a technical proposal, "SDB" was supposed to have a huge dimension and a large mass. With a wing span of 50 m and a bearing area of 300 m², its length seemed to be within 44 m. The largest take-off mass was 140 tons, normal was 110 tons, and the estimated flight range was 12,000 km with 5 tons of bombs on board. The highest bomb load is 20 tons with any set of caliber units from 0.5 tons to 9 tons. The flight speed to the target is 800 - 850 km / h. There was no heavier aircraft in the USSR.
With such calculated data "SDB" enthusiasts turned to the MAP. Minister of Aviation Industry M.V. Khrunichev promptly contacted the Kremlin, and on March 24, 1951, a government decree was signed on the re-establishment of the OKB V.M. Myasishchev 1on the territory of plant No. 23 for the pilot and serial production of a strategic bomber, which was named after the Design Bureau 2M, the military designation M-4 and the factory designation “product 25”. The last cipher was also called a new topic, announced as a shock for related enterprises and institutions of the IAP and other departments of the country's military-industrial complex. A directive was sent to the pilot enterprises of the Ministry on urgent allocation of the necessary contingent of specialists to fill the OKB-23 staff and the largest plant with the indispensable return of those designers and production workers who had previously worked under the control of Myasishchev at plant No. 482. In addition, the recruitment of workers and employees, as well as young specialists from universities and technical schools of all required specialties, was announced for the new enterprise.
There was a rare case when the design engineers themselves put forward to a new level the tactical and technical requirements for the planned aircraft. The Air Force command and the government could only enthusiastically agree and endorse them in the normative act of the assignment for the design and construction of the strategic long-range bomber "SDB".
Without exaggeration to the enchanting event, the preliminary studies of the initiators of the aircraft building department of the educational institute were carried out in stages in several stages. Many variants of the aerodynamic layout, volumetric-weight and structural-power schemes of aircraft of similar and other classes and types were considered, analyzed and eliminated. As a result of the selective selection of layout schemes, the designers settled on two almost identical versions of the preliminary design with the symbols “SDB” and “1M” (M-2). The first of them was presented at the TsAGI STC and illustrated the reports of Myasishchev and Nazarov, and the second, called the “First Machine” (Myasischev - the second) was the basis of a real bomber, which they began to develop at plant number 23.
"SDB - 1M" is a large-sized device of a normal airplane scheme with a swept high wing, swept tail, and a bicycle chassis. The wing along the leading edge had a double sweep. In the root zones (before the fracture), the sweep angle was 45°, and in the end - 40°. The trailing edge, which was occupied by takeoff and landing mechanization and ailerons, had two fractures on each side of the wing, due to local rigidity of the structure due to the level of linear loads and a set of profiles in scope.
Both preliminary options were a reflection of those concepts on a long-range aircraft with turbojet engines, which, being contradictory, coexisted at the turn of the 40s and 50s. According to the constructive-power scheme of the wing and plumage, the options were similar to those developed by A. N. Tupolev Design Bureau, which received the task for designing the 88 product (Tu-16) a little earlier. Here and here, flanged structural and technological joints of the wing consoles along reinforced ribs were used, which divided the supporting unit into four parts and were located at right angles to the longitudinal power elements of the caissons (otherwise, across the construction span of each console). Such a partition was chosen from technological considerations and from aerodynamic conditions. The aerodynamic twist of the wing was alternating, from 8 ° in the root to -3 ° at the ends.
With the American B-47 prototypes and the B-52 being developed, Myasishchev’s aircraft was related by the installation of a turbojet engine with a wing spacing for unloading it in flight. The layout of the first option provided for the suspension of two AM-TKRD-03 pylons under the root parts of the wing and another pair of similar engines under the end parts of the wing. This installation of the force group did not violate the structural integrity and rigidity of the wing caissons. The end turbofan engines were supposed to serve as anti-flatter loads and carriers of the side supports of the bicycle chassis. The second option, “1M”, with a simplified basic trapezoid and wing profiling (without fractures along the trailing edge) was distinguished by the pylon suspension of all four AM-03 engines. The pylons were brought to the top of the wing in the form of aerodynamic partitions. According to the developers, the wing was to be a long flexible caisson with a profiled toe, movable elements and accommodate two (right and left) groups of kerosene tanks. Fuel tanks should not have prevented the elastic but solid construction from undergoing torsional and bending deformations in wide ranges, since with alternating loads in flight, the wingtips can oscillate vertically with an amplitude of more than 2 m. Such “swings” should not interfere with the normal flight conditions of the bomber.
The fuselage of the aircraft in the first version (“SDB”) was prescribed a cylindrical shape with oval cross sections (for nose and tail tapering), which provided an acceptable space for the bomb compartment from the conditions of the internal suspension of two bombs of maximum caliber (for example, FAB-9000) with a vertical package . The remaining volumes of the hull were supposed to be occupied by the crew, fuel tanks and chassis compartments, as well as (“in bulk”) equipment and functional systems. Structurally, the fuselage consisted of and assembled from five autonomously completed parts that docked together on bolted flange frames. The crew consisted of seven people and was dispersed over the bow and tail pressurized cabins: two pilots, a navigator-scorer, two blister shooters, a radio operator and a stern shooter. The second version of the body layout did not have fundamental differences from the first, with the exception of the cross-sectional shape, which became round with a diameter of 3.5 m. This was required to increase the capacity of the fuel system (due to the orientation towards improved more powerful and more “gluttonous” turbojet engines) -03). In addition, the rounded bomb bay could already hold three nine-ton bombs and, accordingly, an even larger number of bombs of smaller caliber than the application version of the "SDB".
The tail unit of the “1M” version was modified according to the results of blowing the “SDB” model in the T-1 MAI wind tunnel and strength calculations by TsAGI specialists, Kiel was moved forward, in the zone of large building heights of the fuselage, and to restore the static moment of the vertical tail surface was increased by 7% due to the expansion of the keel along the leading edge. The horizontal plumage with the same configuration and design was shifted back due to the increase in wing area to match the greater flight mass. In the future, the aircraft promised to gain mass as it is endowed with new capabilities and in the process of improving on-board systems.