M-29 transport aircraft

In the early decades of the 20th Century aircraft designs had not achieved the marked specialisation that emerged in the later decades of the century. Particularly in the Soviet Union, the search for a universal aircraft resulted in designs that were intended to perform the role of both bomber and cargo transporter. Hence heavy bombers were used to transport parachusists, and cargo planes such as the Soviet version of the DC-3 were used to drop bombs. This role ambiguity persisted into the 1960s, with many Soviet cargo aircraft retaining nose transparencies to acccomodate bombardiers, should they be needed.

One of the most visibly successful examples of this design philosophy was the Tu-104 passenger transport, a fairly successful civilian modification of the equally successful T-16 BADGER medium range bomber. The rather less successful but more ambitious Myaschichev Mya-4 long range bomber spawned a design for an equallly ambitious M-29 passenger plane, which remained a paper plane.

Conceptual design "29" (M-29, M-6P), which was developed in 1956 is worthy of attention. In contrast to the basic version of the M-6, the aircraft was designed accommodate 200 - 250 passengers on the upper deck and accompanying luggage downstairs where it was possible to place other target loads. The fuselage had a cross-section in the form of eight. Diameter of the body to the passenger compartment - 4.2 m, with the cargo space - 3.0m Otherwise wing, empennage, landing gear and, of course, engines type VD-7 were from the original bomber. Equipment jobs crew but compared with the prototype also has not changed. Work on the project airbus were discontinued simultaneously with the closing of other topics DB-23. In October 1960 the OKB-23 was transferred to the Ministry of Medium Machine and became a subsidiary of the Moscow Region OKB-52, where the chief designer was one of the founders of space rocketry VN Chelomsy. Materials from DB-23 on aviation subjects were transferred to the DB-51 and PO Sukhoi OKB-156 Tupolev.

Unfortunately, the fate of the outstanding aircraft designer Vladimir Myasishchev was such that during his life he did not have the opportunity to fly a civilian plane into the sky. All meat products be it airplanes or spacecraft, created by defense order. Only once the designer, now back in 1956, managed to develop a draft non-military aircraft, which had the index M-29. It was a passenger version of the famous strategic bomber M-4, featuring a two-deck fuselage. Passengers were placed on the upper deck, and the lower was used for cleaning the bicycle chassis and luggage. In fact, everything turned out to be just a dream: it was not possible to finish the work beyond the preliminary design. Why is it still unknown. But this story is probably not the best, especially if it is unpleasant to say that under the pressure of A. N. Tupolev the construction of the K-7 aircraft designed by K. A. Kalinin was stopped under the pressure of Tupolev the program of the famous “hundred” was curtailed ( T-4) General Designer P.O. Sukhoi. For the M-29, the place went just in the middle between these dates.

Considering the increased demand of the national economy in increasing passenger and freight traffic and the profitability of using high-speed jet aircraft with long flight ranges on long lines, OKB-23 proactively proceeded to the development of a transport aircraft based on the mass-produced M-4 bomber. The topic received the designation - "29". 0. A. Sidorov was appointed project manager. Preliminary studies on the transport version of the M aircraft were carried out in 1953. During this period, the issues of aircraft basing were considered, the possibility of its operation from class I airfields was examined.

The proposed project provided for two versions of the aircraft: passenger and military transport. For the aircraft “29”, a number of units and systems of the M-4 bomber were used without changes: wing, plumage, power plant, control system, fuel system, hydraulic system, fire fighting system and several others.

Aircraft systems had already been developed and completed during the operation of an experimental batch of bombers and therefore had the necessary degree of reliability. The use of many units and all the main systems of the serial M-4 was to significantly reduce the time of design and development of the aircraft in production and operation. Turbojet engines AM-ZA (or AM-ZM) were widely used in the Air Force and were quite reliable. In the future, they were supposed to be replaced by more efficient VD-7 engines, which would increase the flight range and improve economic performance.

When designing the aircraft, special attention was paid to ensuring the safety and convenience of flight. The installation of engines near the fuselage made it possible to continue the flight in case of failure of one or even two of them without a significant deterioration in the characteristics of stability and controllability. Engines were located in special compartments equipped with firewalls. A new fuselage of increased diameter was designed for the aircraft, in which the cockpit and two passenger compartments were arranged. At the bottom of the fuselage placed cargo compartments. Passenger salons had reliable sealing, effective heat and sound insulation. They had to maintain pressure and temperature, providing comfortable flight conditions at high altitudes. To guarantee the safety of passengers, double glazing of the portholes was provided, the fuselage was divided along the length into a number of individual pressurized compartments, and duplication of pressurization systems.

In 1954, according to the Decree of the Council of Ministers of the USSR, design work began on the ZM aircraft with VD-7 engines. Given this circumstance, the design bureau in early 1955 began to study the design of the aircraft "29" with engines VD-7. This engine was lighter than AM-ZA, had greater thrust on take-off and rated conditions and lower specific fuel consumption. Therefore, with VD-7 it was supposed to get a longer flight range and improve take-off and landing performance. Calculations and model studies were performed at TsAGI. In particular, model 29A-1 was purged in the T-102 pipe. The layout of the aircraft with new engines were developed.

Prior to the development of the VD-7 engines, it was planned to release the aircraft with AM-ZM, as the most mastered in operation. True, the flight range with these engines would be slightly less - 4000–5500 km. To refine the layout of the aircraft, a passenger compartment compartment layout was built. The design of the aircraft, developed at the Design Bureau, corresponded to the level of development of modern transport aviation and met the requirements of the Civil Air Fleet for aircraft designed for long-haul lines. The economic characteristics of the machine, calculated by the methodology of the Research Institute of Civil Air Fleet, showed the high efficiency of its operation on lines of any length.

At the same time, the military transport version of the aircraft was worked out. It was possible to re-equip both options for transporting the wounded. A large amount of work on the aircraft was performed by Yu. P. Bobrovnikov. The design data of the aircraft "29" in March-April 1955 were presented in the MAP, Air Force and Civil Air Fleet. As a result of the consideration of the project, the USSR Council of Ministers issued Decree No. 1561-868 of August 12, 1955 and MAP Order No. 571 of August 29, according to which OKB-23 was instructed to design and build a long-range passenger plane M-4P based on the M-4 aircraft with four engines VD-7.

The numbers recorded in the Resolution were significantly different from those stated in the preliminary draft. In particular, the mass of the maximum payload increased by 6 tons and the number of passengers from 100–130 to 179–180 people. This entailed a change in the tactical and technical requirements for the aircraft. In addition, it was necessary to change the chassis layout to eliminate the operational disadvantages of the bicycle layout. For such a scheme, a large thickness of the concrete coating was required, and most importantly, a large width of the runway and taxiway (the track of the M-4 wing supports was equal to the wing span). At that time there were very few airfields with a large runway width and reinforced coating. As a result, a radical revision of the project was required.

In accordance with the new TTT, OKB specialists worked out a new layout of the passenger compartment and a chassis diagram, which showed that despite significant technical difficulties, obtaining the data specified by the Decree, basically, can be provided. However, the continuation of work on the aircraft was not followed. The Ministry of Aviation Industry, as has already happened to OKB-23 more than once, has relied on other "firms" and, accordingly, other aircraft. In OKB-156, work on the Tu-114 aircraft was in full swing, in OKB-153 - on the An-10 and An-12 aircraft and MMZ Strela - on the Il-18. In this regard, on November 30, 1955, the Council of Ministers, by its Decision No. 1966-1055, in order to expedite the creation of other passenger aircraft adapted for transport and landing operations, ordered OKB-23 to cease work on the creation of the M-4P aircraft. In accordance with this Decree and MAP Order No. 766 of December 9, 1955, work on the project "29" was discontinued.

The M-29 aircraft was intended for the transport of passengers on long lines, as well as for the transportation and landing of troops, military equipment and cargo. The aircraft is an all-metal low-wing normal plan with a swept wing and retractable landing gear of the bicycle circuit. The crew of the aircraft consists of five people: the crew commander, pilot-flight engineer, navigator, radio operator and flight engineer. In the passenger version, the crew includes a barman and three or four cabin crew.

The wing, plumage and power plant are used with minor modifications from the M-4 aircraft. The fuselage is double-decked. The fuselage section is formed by two semicircles (upper diameter - 3.7 m, lower - 3.5 m, fuselage height - 4.6 m). The top of the fuselage is sealed. In its front part is the crew’s cabin, next is the passenger compartment, divided into two interconnected compartments. In the lower, leaky part of the fuselage, are the compartments of the main landing gear, cargo areas, aircraft systems and equipment. The wing is a freestanding, swept, caisson structure. Sweep along the line of 0.25 chords - 35 °. Ailerons, flaps and landing flaps are installed along the trailing edge. Ailerons are made split to eliminate spells during deflection of the wing. Plumage is a free-bearing, sweep-shaped normal circuit. The elevators are split. Landing gear of a bicycle circuit.

The trolley of the front support is equipped with a rotation mechanism (the mechanism of "uplift"). A brake parachute is installed to reduce tire wear. Power plant and fuel system. The layout of the engines corresponds to the M-4 aircraft. Fuel is placed in the wing box in soft tanks. For flights over a long range, the installation of additional tanks in special fuselage compartments is provided. Fuel automation is made according to type M-4. There is an emergency fuel drain system in flight. Aircraft systems. All major systems are duplicated. The hydraulic system consists of a main and a booster. The electrical system is divided into two independent with independent power supply.

The control system for rudders and ailerons is booster. Equipment. The aircraft is equipped with a full range of flight and navigation and radio communications equipment. The air conditioning system of the aircraft ensures normal physiological conditions in flight for the crew and passengers and includes devices for pressurizing and heating the passenger cabin and cockpit, as well as individual ventilation devices. The adjustment of the flow rate and temperature of the supplied air is automatic. The anti-icing system is designed to prevent ice formation on the outer surfaces of the aircraft and includes: air-thermal de-icers of wing socks and plumage, engine air intakes and individual engine parts; electrothermal anti-icing glazing pilots. Air for the system is taken from the seventh and eighth stages of engine compressors.

Designed for landing and parachute landing of troops and military equipment, as well as transportation of goods, military equipment, troops with weapons, evacuation of the wounded. The design of a military transport aircraft is basically similar to the passenger version and is distinguished by the presence of hatches for loading and dropping equipment and paratroopers, the presence of a front loading ramp and a reinforced floor of the cargo compartment. The cabin is sealed, equipped with heating, ventilation, a device for removing exhaust gases of self-propelled equipment and emergency oxygen supply for paratroopers and the wounded. In the parachute version, you can load all types of equipment provided for by the requirements of the Airborne Forces, including 85-mm guns and GAZ-bZ cars. The aircraft can accommodate up to 200 paratroopers with full equipment, weapons and ammunition.

The aircraft can be equipped to transport 180 wounded on a unified army stretcher and 15 paramedics. There is a dressing room. In the rear of the fuselage can be installed remotely controlled rifle-gun installation.