Flying boat MDR-6 (Che-2). So say the historians of aviation, Soviet flying boat MDR-6 design Igor V. Chetverikova was one of the most elegant production of the Soviet seaplanes. Its clean aerodynamic shape and streamlined contours of the fuselage talked about the desire of the designer to create an aircraft that combines high speed and greater range. In fact, when creating the MDR-6 was used the experience of the most advanced aviation companies, created flying boats in the mid 30-ies of the last century. Elegant aircraft has left an appreciable trace in the history of Soviet Russia, and the threat of war and, consequently, the growing need to land the aircraft did not allow him to become the most massive flying boat of the Soviet Navy.
The birth of the aircraft
On the plane, which later received the designation of MDR-6 (Che-2), its designer I. V. Chetverikov began working in 1933. The predecessor to it was the distant Arctic scout, ark-3, which was developed for nsra — the seaplane was intended for ice reconnaissance and rescuing crews of ships in distress. However, the plane was mostly interested in the military, who had in mind to use it as a high-speed sea scout with long range.
The establishment of a seaplane demanded production base on the coast, and under the largest defence order of I. V. Chetverikov provided such a base in Sevastopol, which they could not boast many of the designers who worked on similar projects. In early 1936 was completed Assembly of the first prototype flying boats of the ARC-3-1 — aircraft with high wing and two engines of M-25 with a capacity of 710 HP., located on a common pylon above the fuselage in tandem. The aircraft has a large weight impact and that is especially liked the military, the possibility of afloat repair of engines during a forced landing. To combat seaplane this was considered particularly important.
Further increased the interest in the military flying boat world record set on an experimental machine 25 April 1937, when the aircraft loaded with 1000 kg and reached an altitude of 9190 meters. However, successful initial tests were interrupted by the catastrophe that occurred on 14 July 1937.
A second instance of ARC-3-2 built in a military version. The seaplane was equipped with a more powerful engine M-25A at 730 HP, it accelerates to a speed of 320 km/h. But it suffered the fate of the first car. Fateful date for these machines was the date of 14 July. Exactly one year later, July 14, 1938, was lost and the second flying boat, killing the pilot Yershov, flight engineer Perminov and the mechanic Medvedev. Times were tough, and the designer could well join the ranks of the participants one of the “construction of communism”, but this, fortunately, did not happen. On the contrary, I. V. Chetverikov was a regular job for the design and construction of an aircraft of the same purpose.
New flying boat, immediately the designation of MDR-6, differed significantly from the series ARC. I. V. Chetverikov, focusing on the desire of the military to the seaplane with great velocity, completely changed its layout, setting the engines at the edge of a wing type “Chaika” for the first time in our country applied to the marine aircraft.
At the end of 1938 flying boat rolled out of the Assembly plant, however, various improvements were made on it in six months. Flight tests of the machine were made in the period from 2 to July 22, 1939. In their report on the flight tests were high for seaplane speed, resistance in all modes of flight, ease of management, as well as the possibility of flight with one engine running. However, the desire of the designer to achieve high speeds has led to inconvenience in the operation of flying boats.
The report also noted that the turret of the Navigator, located literally a few feet from the water, with a little wave, and taxiing during takeoff and landing zapisyvalas water, which in large quantities into the cabin. The reason for this was too short for the bow of the boat in combination with compressed midsection of the fuselage. It was also noted that due to the proximity of the engines to the fuselage, the Navigator could not safely leave the plane from the cockpit, and had to move to the pilot. Another major comment was related to accelerated wear of the blades of propellers, which during takeoff and landing, fell into the water — the engines were located too close to the surface of the water. As a drawback interpreted the presence of a significant dead zones of fire from the upper turret, which was also the fee for the speed.
Nevertheless, these shortcomings did not prevent the admission Committee to recommend the aircraft for re-equipment of parts of naval aviation. The decision on series production of new flying boats was taken in August 1939. The benchmark for the series was the understudy MDR-6 with the engine M-63 (factory designation — the Latin letter “H”), From the first machine, the aircraft differed mainly by the increased wingspan.
The serial production it was decided to establish at plant No. 31 in Taganrog, before producing a boat MBR-2. Plant staff reacted coolly to a “foreign” car — recently successfully completed tests created in plant MDR-5 and, of course, everyone was hoping that the serial will produce the aircraft. Moreover, the designer of the apparatus G. A. Beriev in parallel with the construction of the experimental boat was preparing the equipment for its mass production. With the transfer of the plant to the new KB had to completely retool the Assembly shop. But despite all the difficulties, the first production of MDR-6 had already gathered in August of 1940.
The establishment of mass production in construction and the equipment of flying boats already in the build process were made a lot of changes, which, however, had almost no effect on the appearance of the plane. Flight tests began in September 1940. Their results have been mostly positive, however manifested, and the old disadvantages. To work for their elimination and fine-tuning of the MDR-6 was connected to the specialists of TSAGI, which outlined a number of measures to improve characteristics of a seaplane. In particular, it was proposed to replace the profile of the wing, lengthen the nose of the fuselage to increase vertical tail above the wing to lift and remove the engines from the fuselage. In order not to waste time and not to stop production, it was decided in accordance with the recommendations of TSAGI promptly prepare documentation in order to begin making changes in design of boats since the second series.
The production and development of the line parts
By December 1940, the factory managed to collect 13 flying boats, after which the Assembly was transferred to other enterprises, giving them and the rest of the groundwork. With the beginning of the war, production slowed down, the main attention was paid to the fighters and attack aircraft, which, of course, was that the company needed. On vehicles produced since the beginning of 1941, we can say that their installation, debugging and commissioning was carried out individually. In units propavshih MDR-6, not even two completely identical seaplanes. All of them differed in composition and location of the equipment, the layout of workplaces of crew members, armament, ground overlay reinforcing plates and ribs. Apparently, therefore, each of the flying boats had pronounced individual flight characteristics. All this led to a large number of breakdowns and accidents on the stage of their development in line units.
According to the memoirs of D. V. Vorobyeva, who flew as Navigator on MDR-6 in the separate reconnaissance squadron of the Pacific fleet, the crews reluctantly transplanted from one seaplane to another, especially pilots. The location of the equipment, instruments and control levers on the machines do not coincide, and in critical situations, pilots were simply lost when working with the cockpit. In addition, the pilots very tired quickly — showed the influence of the strong vibration and the roar of the closely spaced from the cab of the engine.
Long-range Maritime reconnaissance MDR-6 (Che-2) design I. V.Chetverikova:
1 — nose turret NUB-3M; 2 — the window of the cab of the Navigator; 3 — two-blade variable-pitch propeller AV-1; 4 — exhaust pipes; 5 — operating the hatch of the tank; 6 — a cable the radio antenna; 7 — feed (medium) turret SUB-3; 8 — 7.62 mm machine guns И1КАС; 9 — glazing lukovoy rifle point; 10 — cover the bottom rifle point; 11 — water wheel; 12 — 250-kg bomb FAB-250; 13 — wing float; 14 — rudder; 15 — V-shaped strut of the stabilizer; 16 — a turret of MV-5; 17—an access hatch in the cockpit the radio operator and a flight engineer; 18 — band brace wing float; 19 — right ANO; 20 — removable panel of the engine hood; 21 — 12.7 mm UBT machine gun; 22 — bow mooring node; 23 node mounting erratic chassis; 24 — attachment of the tail support; 25 — the tail docking unit; 26 — the cabin hatch of the Navigator open; 27 — the window of the cockpit in the open position; 28 — left ANO; 29 — the bomb racks DER-19; 30 — Luke in the cockpit the radio operator and a flight engineer opened; 31 — cap turrets SUB-3 in the open position: a 32 — dimensional tail ANO; 33 — trimmer of the rudder; 34 — erratic led; 35—Luke lower machine guns opened; 36 — hatch SHKASS machine guns; 37 — wheel bogies erratic chassis; 38 stepladder; 39 — detachable erratic chassis; 40 — Venturi; 41 — balneoclinic; 42 — 20-mm ShVAK cannon fodder turret installation; 43 experimental turret; 44 — rocket RS-132: 45 — ShVAK cannon nose turret installation; 46 window installation optical bomb sight OPB-2; 47 — front wing float; 48 end rib of the wing; 49 — frame radiolucency in the fairing; 50 — cabin Windows pilot; 51 — the cabin hatch of the Navigator; 52 — the air intake of the carburetor; 53 — fold regulation of engine cooling; 54 — the oil tank; 55 maintenance hatch of the tank in open position; 56 — the weight of the Aileron compensators; 57 — cap turrets MV-5 is in the open position; 58 — weight canceller of the Elevator; 59 — pull rudder trimmer; 60 — pull rudder; 61 — skid; 62 — bombs FAB-100; 63 — strut wheeled chassis; 64 — wheel chassis ground version of the aircraft; 65 hinged glazing; 66 hood filler of the oil tank; 67 — stabilizer: 68 —handlebar height; 69 — trimmer of the Elevator; 70 — rocking chair trimmer rudder; 71 — the hinge of the Elevator; 72 — caps of the filling openings of the wing fuel tanks; 73 — Aileron; 74 — hinge Aileron; 75 plug mounting hole bomb sight; the 76 — operating lid; 77, the air intake
Differences in the placement of instruments was not only in the cockpit but also in workplaces navigators. On some aircraft was completely absent from oxygen equipment, making it impossible to fly at high altitudes. It had to be mounted already in the squadron, but, as is usually the case, the permission to install it waited sometimes more than a year. In the run-up and run in the flying boat still got water through navigational turrets — while the mechanics of the squadrons have not finished them. Trapped in the cabin water at a height of froze in the pipes, switches, buttons, sometimes damaging appliances and equipment. As recalled by D. V. Vorob’ev, on the steering even with a small wave, it seemed that the plane is about to dive and go under water. The pilots moved to MDR-6 seaplane Beriev G. A., considered a bad review from the pilot seat. All this led to a high accident rate.
As the main advantage of the WDM-6 was noted for its high speed and ability to carry out such maneuvers that were impossible for other seaplanes. Some squadron pilots served cool combat turns, bends with large angles, flips and even barrel. However, after the fuselage of one aircraft was warped and the car miraculously did not collapse in the air, this whole “circus” was discontinued willed command. However, the pilots still sometimes away from the commander’s eyes, allowed himself to warm up. About the same mastered flying boat and other parts that received MDR-6. By the way, by this time, the seaplane was given a new name — Che-2, the first letters of the surname of the chief designer.
The development of the design
During the testing of the flight characteristics of the prototype aircraft was considered satisfactory, but it was clear that you have to work for their significant improvement. Before the KB team was tasked approximation of the characteristics of flying boats to bombers DB-3. To improve the flying boat designers do immediately after the transfer of MDR-6 into production. During the period from 1940 to 1946, was created by modification of a seaplane, which bore the General name of MDR-6, but labeled “A” and “B” with numbers from 1 to 5.
MDR-6-And took to the air in 1940. The basis of his project was based on the concept and design serial MDR-6. In attempts to significantly increase the speed of flight, the designers critically revised the contours of a seaplane in search of the most advantageous aerodynamic form. To reduce takeoff and landing speeds on the wing had flaps. Glazing of a cabin of the pilot and the Navigator was redesigned to be more streamlined, the aft turret was moved behind the rear of the redan. A significant proportion of the speed increase promised to install inline engines liquid-cooled M-105 is a radial engine air-cooled M-63, having a large frontal resistance. To reduce the overall aerodynamic drag was also designed underwing floats box shape, retractable flush into a recess of the wing between the spars. The wingspan was reduced from 21 to 16.2 m, wing area and consequently decreased by 11.4 m2.
Flying boats with indexes A and B-1, according to aviators, quite claim to be the most elegant flying boat ever released in the USSR. To improve the efficiency of the rudders, especially at low speeds (takeoff, landing and taxiing), was re-designed vertical tail instead of the fin on the ends of the stabilizer in the areas of air jets from the screws were placed two keel washers. Test conducted seaplane pilot D. Slobodchikov. Achieved during the speed test (454 km/h) was the highest for the aircraft of this class not only in the USSR but in the world. But other characteristics — in particular, seaworthiness and a range of needed improvements.
Boats index b-1 and B-2 was produced in 1940-1941. B-1 was practically identical to MDR-6-A, differing from its predecessor only by increased displacement floats. The planes were inline engines are water-cooled M-105 (VK-105) with a capacity of 1050 HP, the vertical tail is made according to the posted diagram. The Assembly of the B-1 was completed in December of 1940, of the testing machine was held in March and August next year. B-2 collected in June 1941, and the factory tests were completed in October.
The aircraft was able to correct some of the defects which “sinned” MDR-6. So, it was completely excluded water from entering the cockpit of the Navigator, improved field of fire from the aft turret. By lengthening the bow of the hull improved the seaworthiness of a seaplane and landing characteristics. The changes were made and weapons on seaplanes were machine guns BT. As the shortcomings noted the proximity of the screws to the water (the defect is moved from a flying boat with the index “N”) and unsatisfactory operation of the mechanism for cleaning the supporting floats. The aircraft managed to reach a top speed of 454 km/h, which was exceptionally high.
Unfortunately, to complete the test program failed — 16 Oct 1941 flying boat B-1 crashed near the town of Uglich in the execution of the flight to a new location KB. Not been completed and testing of B-2 because of defects of the power plant. B-3 and B-4 were released, respectively, in December 1943 and March 1944. On the boat to install the engine VK-105PF with a capacity of 1150 HP with frontal radiators. The aft turret was replaced by two lateral blisters with 12.7 mm UBT machine guns, which led to an increase of the crew to five people. The size of the B-3 did not differ from B-2, but increased take-off weight significantly worsened the seaworthiness of flying boats. She sat deep in the water and could not take off even with a small wave. It was also noted the increased noise in the cockpit.
In 1943, flight tests of the flying boats was over, but by that time requirements range Maritime reconnaissance was increased to 3000 km, which resulted in the next prototype MDR-6-B-4, made first flight in April 1944. B-4 had significant differences from the B-3. Was increased the size of the boat — its hull is wider by 300 mm and above 400 mm. the area of the vertical tail increased by installing additional Central keel. Back redan shifted back, underwing floats steel fixed — the reason was the unstable operation of the mechanism of their harvest in the previous machines. For installation of the floats was used N-shaped rack. The changes gave the boat good stability even at high tide. Changes were made in the system of defensive small arms — equipped with two newly designed blister card with extended fields of fire. Due to the changes significantly improved seakeeping, but the rate decreased by 24 km/h. The first flights of the B-4 showed that the directional stability of the aircraft is insufficient. To remedy the defect on the machine installed additional Central third of the inner keel.
MDR-6-B-5 rolled out of the Assembly shop in the summer of 1946. Although this boat was a further development of B-4, she reminded her only superficially. According to the main characteristics — size, hardware, location and composition of the crew — it was a completely new and original machine. When you create an aircraft designer were to abandon the goal to catch up to land aircraft on the main characteristics, and primarily for speed and maneuverability.
After several attempts to combine these qualities with high seaworthiness in KB came to the conclusion that the main emphasis should be to improve navigability and increase the flight range of the boat. The practice of creating prototype flying boat showed that growth of high-speed characteristics, they always lag behind the land scouts and bombers (the end of the war the speed of these aircraft often exceed 600 km/h). Even with a perfect aerodynamic shape and retractable floats lateral stability the presence of the redan on the bottom of the boat and enlarged midsection of the hull did not allow the boat to reach speeds comparable with the speed overland of the aircraft.
Another modification of MDR-6-B-5 was created for the purpose of receiving flying boats with long range and high seaworthiness. The prototype of this modification was the seaplane, B-4, the design of the wing and fuselage which was made only minor changes. In particular, due to the increase in amplitude of the center section of the wing was lengthened by 500 mm, while the wing is left unchanged. The hull was also lengthened to 500 mm. an Additional section mounted at the front of the fuselage before the wing. The cockpit and the workplace Navigator moved forward to improve visibility. Due to the increase in centroplane fuel tanks increased the fuel capacity, thus bringing a range of boats up to 3,000 km. boat Crew consisted of four people — two pilots, Navigator and radio operator-gunner.
Changes were made in the design of the tail. Due to the increase in the area of the keel washers have the opportunity to unsubscribe from the middle of the keel, and the vertical tail again became a two-keel. Significant changes were made to the armament in one place with machine guns took three guns B-20: the one with the ammunition to 200 rounds fixedly mounted in the forward glass hood of the cab of the Navigator, and the other two aft turrets SEB (aircraft-electric tower) ammunition 300 rounds per gun. From the lateral blisters with a single 12.7 mm machine guns firing to the rear hemisphere, as in the B-4 — refused because of their low efficiency and unsatisfactory review. In addition, the blisters created significant drag. To attack sea and ground targets B-5 could carry bombs caliber 100, 250 and 500 kg total weight up to 1000 kg.
The aircraft was equipped with two engine VK-107 with a capacity of 1650 HP each with changed nosing, which improved the overall aerodynamics of the aircraft and the underwing tunnel vodoradiatory mounted instead of the front. In the same set and cooler. Unfortunately, more powerful engines are unable to compensate for the increased take-off weight and the aircraft size, so the maximum speed of flight B-5, amounting to 380 km/h, was less than that of the earliest versions of the MDR-6.
However, the task of creating a flying boat with high seaworthy qualities and a large range of flight was solved. During testing, the pilots noted the excellent seakeeping and good manoeuvrability in flight. The aircraft is satisfactorily passed production tests, but state tests is not passed.
N. Food reserve was, A. CHECHIN
(To be continued)
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