Long-range bomber First flight: 1937 Bolkhovitinov

DB-A (long-range bomber - academy) Bolkhovitinov can be considered as a qualitative step in aircraft construction. Unlike the TB-3, it had a smooth skin, metal propellers with adjustable blade angles on the ground, Schrenk landing flaps, a retractable tail and semi-retractable main landing gear wheels, a 6x2 m bomb bay, a Tur-8 mechanized shielded turret, a non-adjustable stabilizer and closed, except for the stern gunner, cockpit.

The semi-monocoque fuselage made it possible to significantly increase the free internal volume with the same dimensions as the TB-3. Under the center section in the fuselage there was a bomb bay that could hold up to 3000 kg of bombs in the following options: 8 bombs of 250 kg, 6 bombs of 500 kg, two of 1000 kg or 24 of 100 kg. Provision was also made for the suspension of VAP-500, VAP-1000 airborne discharge devices and RRAB rotary-dispersal bombs.

In the forward part of the fuselage there was a Tur-8 turret with a ShKAS machine gun, and in the central part of the fuselage there was a Tur-Aldis turret with a 20 mm ShVAK cannon. In the tail they provided dagger and stern installations with ShKAS machine guns. The total supply of ammunition for machine guns was 3,000 pieces, for a cannon - 250 pieces.

The high-mounted three-spar wing, made from TsAGI profiles - 620 percent thick, consisted of a center section and two consoles. The toe and rear part of the wing are one-piece. Nine gas tanks held 14,600 liters. Two oil tanks with a capacity of 460 liters were divided into two parts by sealed partitions and were located in the wing toe between the engines.

The use of landing flaps with a deflection angle of up to 60° made it possible to reduce the landing speed to 80 km/h.

Bomb racks were installed under the wing, designed to carry up to 2000 kg of bombs. Removal and release of wheels, as well as landing flaps, rotation of the bow machine gun mount, opening and closing of the bomb bay were carried out using pneumatic actuators.

The APR-3 radio direction finder was installed on the DB-A (later on the aircraft with the USSR H-209 index it was replaced with a Fairchild radio half-compass). The project involved the installation of an AVP-10 autopilot. Communication between crew members was carried out using pneumatic mail and an aircraft intercom. To ensure landings at night, the aircraft was equipped with underwing torches.

The power plant consisted of M-34RN engines with gearbox and supercharging. The project was designed for the uprated M-34FRN, but they appeared much later.

Initially, the DB-A engines were equipped with two-bladed wooden propellers with a diameter of 4.35 m from the TB-3, which led to a decrease in flight characteristics compared to the calculated ones. Subsequently, they were replaced with three-bladed ones with a diameter of 4.1 m from the ANT-25 aircraft.

Tricycle landing gear with tail wheel. The main racks were equipped with single wheels measuring 2000x450 mm. To operate the aircraft in winter conditions, special skis were provided. But they were never made, and during the tests skis from TB-3 were used. The shock absorbers of the wheeled chassis are telescopic, oil-air, and the shock absorbers of the ski chassis are mixed: cord and oil-air.

DB-A, in terms of its characteristics obtained during factory tests, was significantly superior not only to its predecessor, but also to the closest foreign four-engine bomber, Farman-222. The improvement in the flight characteristics of the vehicle was due to an increase in aerodynamic quality, the maximum value of which reached 15.

The list of shortcomings of DB-A consisted of 38 points, including:

1. insufficient stability and controllability. In normal mode, the plane suddenly spontaneously began to gain altitude, then losing speed, lowered its nose and began to accelerate, falling into a tailspin, and it was not so easy to pull it out;

2. the ailerons of the aircraft are ineffective and the pressure from them on the steering wheel is high;

3. The rudders are ineffective and the pressure on the steering wheel and pedals is high;

4. in rough conditions, the efficiency of the tail decreases sharply and the aircraft loses controllability; a long flight in rough conditions is impossible, because it quickly exhausts the pilot;

5. exhaust manifold pipes are on fire;

6. Gas analyzers give inaccurate readings;

7. poor visibility from the low cockpit interferes with landing;

8. four motors are not very powerful.

To eliminate these and other shortcomings, improvements were necessary in the propeller group and tail unit...

* * *

Bolkhovitinov (and Baidukov too) reacted sharply negatively to the idea of ​​using the only DB-A undergoing flight tests for transpolar flight. It was a military bomber, completely unsuited to flying in the north. Bolkhovitinov gathered a team of designers in the office of the director of the aircraft plant, B.N. Tarasevich, to whom it was announced that the government had granted Levanevsky’s request and on June 5 allowed the DB-A to fly on the Moscow-North Pole-Alaska route. The aircraft was assigned the polar aviation index “USSR-H-209”. By this time, the total flight time of the DB-A was 115 hours.

Stalin, who treated Sigismund Aleksandrovich Levanevsky well, allowed him to choose his own aircraft for the flight across the North Pole. The pilot refused Tupolev’s cars and opted for the heavy four-engine bomber of Viktor Fedorovich Bolkhovitinov DB-A, which received the tail number “USSR - H-209” and the call sign “RL” (i.e. Radio Levanevsky). For the flight, the military vehicle had to be re-equipped - the machine-gun turrets were removed from it, the navigator's cap was completely glazed, and the bomb bay was converted into a cargo compartment. The designer himself was against this choice, since he believed that his plane was not suitable for such flights - it was one of the first experimental models.

Levanevsky's crew before departure. From left to right: Navigator V. Levchenko, radio operator N. Galkovsky, crew commander S. Levanevsky, co-pilot N. Kastanaev, flight engineer N. Godovikov. August 12, 1937

On August 12, 1937, the plane numbered “USSR - H-209” took off from Moscow. The aircraft was supposed to follow the route Moscow - Arkhangelsk - Rudolph Island - North Pole - Fairbanks (USA). From Fairbanks, the plane was scheduled to fly to New York after refueling. The day after departure, on August 13 at 13.40, the plane reached the North Pole.

About an hour after this, the crew sent a radio message, which was subsequently deciphered as follows:

“I-RL, 14 hours, 32 minutes. The right outer motor failed due to a malfunction of the oil system. Let's go for three. Altitude 4600. We are walking in continuous clouds. Levanevsky."

The plane has disappeared, the coordinates are unknown. The search yielded no results.

Photo	Description
	Drawing DB-A 4 M-34RN
	DB-A "USSR - H-209", preparation for departure.

Bibliography

• History of aircraft designs in the USSR, 1938-1950. /V.B. Shavrov/
• Academic bomber / Nikolai Yakubovich/
• Grave cross / Yuri Kaminsky, Dmitry Khazanov./

04/06/2024.
Despite the solemnity of the event (there was even a rally), it was a sad parting. The pilots from Levanevsky’s crew hid their eyes and said goodbye as if they would never meet anyone else. Before the start, Levanevsky told his friends that he would not go back on this flight, as was the case in 1935, but would go to the end. ... The mood of the crew members felt some kind of depression and anxiety, some kind of doom. Almost everyone had sad faces.
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04/06/2024.
I.D. remembers Papanin, who was during the flight at the drifting scientific station "SP-1" at point 87° 20' N. and 0° 00' longitude:
“Soon we... learned that the plane’s rightmost engine had failed. “It’s very difficult to fly on three, it’s flying in continuous clouds”... - they reported from the plane. This message ran through everyone like an electric shock. We realized that the situation was very serious. If such a persistent, reasonable and experienced pilot as Levanevsky radioed about this, then it would be very difficult for the crew... Everyone felt such pain, as if something had snapped in their souls... It was already late afternoon, and no more messages were received from Levanevsky. This silence worried and worried us very much, but we continued to work. They thought that he continued to fly forward on three engines, and his radio station “soured”, as happened with Vodopyanov’s plane when we landed at the North Pole... A message came from Moscow that the radio station of Levanevsky’s plane was being monitored. Ernst was asked to monitor the emergency radio wave; maybe the plane landed on the ice and now its emergency radio is working..."
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04/06/2024.
August 14, 1937 Newspapers in many countries reported the disappearance of the plane. TASS reported from Paris:
"...This morning at dawn, American Air Corps aircraft take off from bases in Alaska in search of Levanevsky and his comrades."
But from Alaska it was not possible to “reach” the site of the alleged disaster - the planes did not have the required flight range. The weather throughout Alaska was exceptionally bad. In Fairbanks, authorities believe that: “... because of the storm... Levanevsky sat on the ice, preferring to save fuel rather than fight the wind...”
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04/06/2024.
Arctic bad weather shackled powerful search forces for a long time. Soviet pilots from Vodopyanov’s search party were able to make their first flight in search of the missing Levanevsky crew only two months after the disappearance of the H-209. Time was catastrophically lost... The search for H-209 dragged on. On November 21, 1937, the sun was last seen from Cape Barrow, Alaska. The polar night has arrived. The number of search flights could be counted on one hand. All of them took place in very difficult conditions.
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04/06/2024.
Probably the defect that played a fatal role during the flight of Levanevsky’s crew across the North Pole was the increased oil consumption of the fourth engine before it was completely depleted, and if we take into account the fact that the right outer engine was smoking even during takeoff, it turns out that the fatal the malfunction was still hidden on the ground, before takeoff.
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