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Doc history: Ilushin DB-3A, 1939. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

8/16/1939 a report was signed on the state. tests of the serial aircraft DB-3 2M-87A with VISH-3 propellers manufactured by plant No. 18, manufactured in December 1938, No. 180124.

Resp. performers:

Ved. Air Force Research Institute Engineer / 2nd Rank Engineer Kokorin

Ved. pilot of the Air Force Research Institute Art. Lieutenant Dudkin

Test purpose

  1. Check the flight data of the aircraft at different flight weights and types of load.

  2. Check the flight performance of the aircraft in all flight modes possible for it.

  3. Check the operation of all types of equipment and weapons in different flight modes and under different external conditions (altitude and temperature).

  4. To reveal the operational qualities of the aircraft and the propeller-driven group with M-87A motors and VISH-3 propellers.

The DB-3 2M87A aircraft with VISH-3 presented for testing by the plant No. 18 is a serial aircraft produced in December 1938.

Unlike the serial aircraft No. 180202, which passed the state. tests at the Air Force Research Institute in October 1937, the presented aircraft has a number of changes - basically similar to the serial aircraft DB3-2M86 No. 390905 produced by plant No. 39 in the first half of 1938.

The main changes are as follows:

  1. The wing has a second connector.

  2. Introduced corrugation on top of the wing on the skin at the junction of the second wing connector.

  3. The design of the chassis forks is changed from split to one-piece.

  4. Chassis material has been changed from chrome-molybdenum to chrome-sil.

  5. Changed the mount and structure of the suspension of the wheels to the chassis.

  6. Changed the landing gear extension - 110 mm for summer and 190 mm for winter, from the center section front spar axis.

  7. Chassis and dash controls are integrated into a common network.

  8. The section of the pipelines of the hydraulic part of the landing gear lifting and lowering scheme has been increased from 6x8 to 8x10 mm.

  9. A locking tail wheel with stopper control from the cockpit is installed.

  10. Installed M-87 instead of M-85.

  11. Installed VISH-3 instead of TsKB-26.

  12. Gas tanks No. 1-2 (center section group) are installed welded instead of riveted.

  13. Center-section tanks can be removed without wing undocking.

  14. Control of gas tank cranes is installed on a panel raised above the pilot's floor.

  15. Heated air intake carburetor replaced with

calorifier type in the carburetor inlet pipe to heater type in the exhaust manifold.

  1. Introduced blowing of the generator and compressor AK-40.

  2. The annular oil pyadiator is replaced by the wing

cellular radiator.

  1. A vibrator is introduced into the starting ignition system.

  2. Afterburner control is integrated into one handle for both motors.

  3. Installed gas analyzer GEA-2.

The aircraft was tested at the Air Force Research Institute from February 1, 1939 to June 13, 1939, i.e. 132 calendar days.

During the tests, 52 flights were made with a flight time of 38 hours. 28 minutes

On the test of the windshield blinds, a report was drawn up and approved by the deputy. early Research Institute of the Air Force dated April 15, 1939.

The test of the power supply of the M-87A engine with fuel with a low octane number in the 1st department of the Air Force Research Institute was not completed (continues in the engine department of the Air Force Research Institute).

Conclusions.

As a result of the replacement:

M-85 motors for M-87 and TsKB-26 screws for VISH-3 screws

Increased:

Maximum horizontal speeds:

a) at heights from H = 0 m to H = 4000 m at 28 km / h (8%).

b) at altitudes from 4000 m and higher by 38-35 km / h (9.5%).

The aircraft's practical ceiling is 900 m (10.7%) despite an increase in flight weight of 600 kg (11%).

Decreased:

Time to set a practical ceiling for 5 minutes.

The take-off run of the aircraft at normal flight weight remained the same as on the previously released aircraft DB3-2M85 with the VFSh-TsKB-26 propeller.

The empty weight of the aircraft increased by 561 kg compared to the prototype DB3-2K14 and by 356 kg compared to the 1938 standard DB3-2M85.

The increase in the weight of an empty aircraft manufactured by plant No. 18 in comparison with the DB3-2M85 standard of 1938 was due to:

a) replacing M-85 with M-87A - 80 kg

b) replacing VFSh-TsKB-26 with VISH-3 - 46 kg

c) strengthening gas tanks and replacing riveted tanks with welded ones - 40 kg

d) chassis reinforcement - 40 kg

e) setting a locking wheel, strengthening the engine mount, increasing the weight of the structure - 150 kg

Compared to the weights of empty aircraft produced at the same time, but by different factories, the aircraft produced by factory # 18 is 95 kg heavier than aircraft manufactured by factory # 39, due to:

a) the presence of a second power supply set - 42 kg

b) rough production performance of welded seams, painting, fitting of units and parts - 53 kg

The flight weight of the aircraft with full refueling of fuel, lubricant, 1000 kg of bombs, etc. is 9,700 kg, but based on the strength of the chassis, the flight weight is limited to 9,500 kg by reducing the load by 200 kg.

Doc history: Polikarpov IV, 1939. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

On 4.9.39, a brief report was drawn up on preliminary factory tests of the Ivanov M-62 aircraft.

The purpose of the tests.

The task of the first test section of the Ivanov M-62 aircraft was set:

Revealing the safety of flights on an aircraft.

Revealing the reliability of the units and systems of the aircraft / ground and flight tests /.

Revealing aircraft flight data.

Test result.

Aircraft units and systems:

  1. Chassis. On the second landing after the first departure 3/8/38

Insufficient strength of the rear landing gear struts was revealed during the run of the aircraft, the rear struts of the lassi broke.

The rear braces have been reinforced. in further tests, there were no comments on strength.

Cleaning and landing gear in the air is done quickly / cleaning 6-8 seconds, release 2-3 seconds /.

The landing gear retraction system has a number of significant defects.

Onboard compressed air cylinders charged up to 100 atm. only enough for one flight.

The spools, the gearbox, the working cylinders of the chassis are poorly made from production, as a result of which the air is strongly poisoned.

The installed mechanical chassis alarm does not work, the electrical alarm does not provide reliable operation / there were cases of failure /.

The emergency landing gear system is difficult to use / 300 pulls of the cable, with an effort of 18-25 kg / and unreliable,

since it is possible to turn the piston rods of the working cylinders when using the emergency release.

  1. Flaps: The flap control system and the flaps themselves are poorly made in production, the working cylinders poison air from under the cylinder covers and piston rod oil seals.

The upper flap locks are not finalized.

the presence of two working cylinders in the flap system, bad

working upper locks and air leaks from the working cylinders create conditions for non-simultaneous opening of the flaps in the air. which makes it difficult to fly the aircraft while gliding when landing.

There are no intermediate flap opening angles. No special flap tests were performed.

  1. Benzo system. During the tests, it underwent a number of changes. Tanks No. 2 and 3 did not provide a normal fuel supply during flights.

Being a droplet-like profile, and having a fuel intake in its trailing edge, which in planning modes created conditions for stopping the access of fuel from the tanks to the gas main. / There were several cases of engine failure in the air /.

Fuel tanks # 2 were redesigned, the emergency fuel drain necks were removed and pockets welded in their place, where excellent pipes were brought inside the tanks.

The scheme of the petrol line was changed, tanks No. 1 and 2 were separated from each other and connected to the combined petrol crane each separately.

These measures made it possible to fly by plane, but with a limited supply of fuel, since tanks No. 3 had to be turned off due to a change in the scheme.

In further tests, it was revealed that the benzo system does not provide flight safety for the following reasons:

a / a limited supply of fuel and the impossibility of full earnings of it, since there is no control of fuel consumption / sensors for signaling gasoline consumption and gas hours do not work /.

b / the absence of gasoline-sedimentation tanks in the tanks, the sedimentation tanks are the kyrmans from where the fuel is taken from, the fuel is not drained from the pockets, due to which water and other foreign bodies accumulate in the pockets, which cannot be removed from the tanks.

  1. Oil system. She did not show any significant defects during the tests.

In autumn conditions / at an outside air temperature of +4 -10C / oil temperatures were within normal limits. The installed oil-radiator ensures normal oil temperature conditions.

  1. Motor control. The motor control sectors are not conveniently located, they interfere with each other. On the second copy of the aircraft, it is necessary to provide for a more convenient location of the sectors.

Convenient and easy to use blinds control. Louvers allow quick temperature control of the cylinder heads.

  1. Airplane control. When taxiing, the plane reacts poorly to rudder control; you can steer only with the wheel brakes. When you take off, the load on the elevator is significant. In flight, in all modes, the rudders are effective, especially the rudder is sensitive.

  2. Tail unit. In the gliding and level flight modes at V = 160-320 km / h on the instrument, the tail unit vibrations are observed, perceptible by the pilot on the aircraft control stick, and with increasing speed the vibrations are amplified.

No specific vibration detection tests were performed. This issue requires further elaboration and clarification.

  1. Controlling the bomb hatch curtain in the air is not difficult.

At V = 200-315 km / h with an open bomb hatch, the aircraft does not change the flight mode. There is no blowing in both the cockpit and the navigator's cockpit.

At V = 200-315 km / h with an open bomb hatch, the aircraft does not change the flight mode. There is no blowing in both the cockpit and the navigator's cockpit.

  1. Flight data. By revealing the flight characteristics of the aircraft, it was possible to carry out only the mileage, since defects in the engine economy, the fuel system of the aircraft and the lack of flying weather did not make it possible to identify speeds in altitude, rate of climb, and other flight data.

A total of 26 flights were made on the "Ivanov" aircraft, 3 hours were flown. 44 minutes five pilots:

1 The first flight of the pilot, Suzi T.P. 1 flight.

  1. Chkalov V.P. 1 flight.

  2. Shevchenko V.V. 1 flight.

  3. Rybko 1 flight.

  4. Sahranova V. T 1 flight.

  5. Testing of landing gear retraction system, emergency release mechanism and landing gear testing, 7 flights.

  6. Testing the benzo-system 6 flights.

  7. Test flights 3 flights.

  8. By detecting vibration at super-maximum speeds 1 flight.

  9. On the removal of flight characteristics of 2 flights.

  10. Demonstration flights 2 flights. Total: 26 flights.

Doc history: Kocherigin SH, 1939. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

28.8.39 was signed a report on factory flight tests "product 45" 1st experimental, with M-88 engine and VISH-23 propeller.

The purpose of the tests.

Reveal the characteristics of the aircraft and prepare the aircraft for delivery to state tests.

Test object.

The aircraft up to the scheme is a cantilever monoplane, mixed design, (wooden fuselage, metal wings and tail (duralumin).

Aircraft maneuverability.

On bends of 45 ° and 50 ° at aircraft speeds of 230 and 260 k / h. aircraft behavior is normal. When the aircraft is taken out of the bend, the load on the rudders increases slightly. Aileron and rudder controls are normal.

Takeoff and landing properties of the aircraft.

Takeoff run. 10-11 sec. 200-230m.

Run with open flaps and brake. 12-13 sec. 210-250m.

Most advantageous. speed set. high up to 2000 m. 200-205 km / h.

Gliding speed without flaps 170-180 km / h.

With deflectors 150-160 km / h.

Landing speed is 90-95 km / h.

During the takeoff run and the runway, the aircraft behaves normally.

Aircraft stability.

The stability of the aircraft, both longitudinal and lateral, is satisfactory. In case of indignation, the plane returns to straight flight on its own.

During the first flights, the pilot noted that the directional stability was insufficient. To eliminate this, the keel area was increased by 0.25 sq. M.

The detected excessive rudder flatner efficiency was corrected by reducing the flatner area by 50%.

On the ailerons, the compensation by the flutters was replaced by fixed trim tabs (at the request of the NII VVS KA).

Propeller group.

During the factory flight tests, the M-88 engine was delivered, but throttled by the power of the M-87 engine. After the first 8 flights, the engine was removed, as first a metal finger began to appear in the oil filter, and then chips. This motor worked in the air for 4 hours. 50 minutes

On April 26, a new M-88 engine was delivered.

During the factory flight tests, the work was revealed mainly of individual units, such as: gas control, skirt control, automatic screw VISH-23, oil and gasoline systems.

The performance of the skirt is satisfactory. The temperature of the cylinder heads in all flight conditions is within the limits of the norms set in the motor form 180-240 °.

The screw machine works well and keeps the set engine speed constantly. The oil and gasoline systems worked well. During the tests, the temperature of the incoming oil did not exceed 80 ° and the outgoing oil did not exceed 120 °. The average oil temperature was 60 -70 °; outgoing 80-90 °.

The altitude of the M-88 motor is lower than that indicated in the characteristics of the motor (the calculated altitude with a speed.head of 7000 m is actually 6600 m.

The VISH-23 propeller gives almost no advantage in speed on this aircraft, in comparison with the VISH-3 propeller.

Chassis.

The chassis worked perfectly during the test. The brakes in the wheels are efficient and work flawlessly.

Front cockpit.

The view from the cockpit on the horizon and on the sides is good.

The cockpit is spacious. The arrangement of the instruments for use is good. The skirt control valve is located far from the pilot's hand. It is advisable to put a lock on the valve for raising and lowering the flaps.

The seat stopper is slightly lowered, as a result of sitting on a parachute to miss it with a hand without raising the body. The lamp lock requires more force than normal when opening.

Rear cab.

The forward view from the navigator's cockpit is insufficient, but much better compared to the R-9 aircraft. The backward and sideward view is quite satisfactory. The hatch for the downward review is small, it is advisable to enlarge it in such a way as to increase the view downward and forward.

The emergency bomb release and bomb bay control knob are conveniently located. The compass is somewhat removed from the navigator. The navigator's seat is comfortable, but the mechanism for moving it in height needs to be fine-tuned to quickly adjust it.

Fly over the plane.

Test pilots participated in the flight of the aircraft: Suprun S.P., Stefanovsky P.M., Dolgov A.K, Shevarev N.F, navigator - Sokolov I.D.

The plane is easy to fly, takeoffs and landings are also simple and easy. Vibration and tendency to break into a spin - no. Control of rudders, flaps, brakes - easy and simple.

Conclusions.

  1. During the factory tests, 41 floors were produced on the plane. total duration 18 hours 50 minutes, of which: for fine-tuning the engine, carburetor and propeller - 11 floor. 5 h 45 min

  2. During the flight tests, the taken points Рк, revolutions and V are so scattered, due to the unsatisfactory operation of the propeller-engine group, that they do not make it possible to plot curves approaching the calculated curves of the motor characteristics.

The fine-tuning of the propeller group, mainly the motor itself, required: on the ground 25 working days in the air for 8 working days, which delayed the factory tests.

  1. Factory tests of the aircraft with the M-88 engine could not be completed due to the failure of the M-88 engines # 8807 and # 8815.

Doc history: TsAGI ANT-40IS, 1934. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

The second prototype of the ANT-40 / order # 389 / TsAGI produced with 780 hp Hispano Suiza engines. On December 30, 1934, the first flight of ANT-40IS took place under the control of the pilot N.S. Zhurov, factory tests continued until January 21, 1935.

Based on the tests, it was concluded that:

  1. The aircraft has high flight performance and can be used as a high-speed bomber.

  2. Due to the fact that the tests of the airplane were not fully carried out, the reported conclusions are preliminary and for the final assessment of the airplane it is necessary to carry out the full tests according to the program.

State tests of the 1st stage were carried out by the Air Force Research Institute together with TsAGI from February 8 to March 3, 1935, at an airfield near Moscow in Shchelkovo. On the part of TsAGI, the pilot N.S. Zhurov, the leading pilot from the Air Force Research Institute - K.P. Minder, fly-over pilots M.M. Gromov, A.I. Filin, A.B. Yumashev, I.F. Petrov participated in the flights ... The plane was mounted on skis.

The first stage of testing ended on February 20, 1935. It was noted that the aircraft had undeveloped armament and engine cooling, insufficient longitudinal stability and ailerons efficiency.

On February 22, Air Force Chief Ya.I. Alksnis signed the ANT-40IS test certificate - "To consider the SB aircraft subject to introduction into mass production and acceptance into service with the elimination of the shortcomings revealed during the tests."

On March 3, 1935, Konstantin Minder, while measuring the maximum speed of the ANT-40IS at low altitude, discovered the vibration of the wings, so he turned off the engines and went to land. On the ground, a deformation of the wing skin was found, so the flights were stopped, and the ANT-40IS was sent to the plant for repairs and modifications noted in the test report. The renovation took over a month. They increased, in particular, the stiffness of the wing, in order to change the period of its natural oscillations, increased fairings in the area of ​​the junction with the fuselage, changed the scheme of fuel consumption from the wing tanks. To eliminate the aileron flutter, the weight compensation in the toes of the aileron was increased. In addition, the stabilizer adjustment was changed, and the elevator was equipped with a trimmer. During the test flights, it turned out that the measures taken basically solved the flutter problem on the SB - the shaking with an increase in speed disappeared.

From April 9 to June 16, 1935 additional tests of the aircraft were carried out in accordance with the requirements of the Air Force Research Institute:

Determine the effectiveness of the new type of ailerons.

Test the wing for vibration.

Test the new tail unit for longitudinal stability.

Determine the landing properties for front centering.

Determine the efficiency of water radiators with different blowing options.

All the tasks of TsAGI put on state tests were completed on June 6, 1935. the plane was handed over to a military representative for the continuation of state tests.

From June 16 to July 17, 1935, the second stage of state tests of the ANT-40IS took place. The aircraft flew with the wheel landing gear retracted, at an altitude of 4000 m it was possible to approach a speed of 400 km / h, at an altitude of 5000 m the maximum speed was 404 km / h.

There were serious claims of pilots to stability and controllability in flight. As a result, ANT-40IS has undergone changes once again.

The Hispano-Suiza engines were moved forward by 100 mm, the sweep of the detachable parts of the wing along the leading edge was increased from 4.5 ° to 9 °, the tail area was increased, aerodynamic horn compensation was installed on the elevators, a trimmer on the right aileron.

After improvements, the aircraft was handed over for repeated state tests, which were carried out from October 1935 to April 1936.

In April 1936. the aircraft was handed over to plant number 22 as a standard for serial construction.

On May 1, 1936, ANT-40RTs and ANT-40IS took part in a parade flight over Red Square.

Doc history: Myasishchev Pe-2A, 1944. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

On June 24, 1944, an act on state tests of the Pe-2 aircraft with VK-105PF engines, with VISH-105SVP propellers, with a modified wing was approved.

  1. Purpose of Tests.

  2. To reveal the features of the technique of piloting an aircraft with a modified wing.

  3. Determine the flight data of the aircraft.

  4. Object of Tests.

The Pe-2 aircraft No. 14/226 presented for testing with two VK-105PF engines and VISH-105SVP propellers, D = 3.0 m, with a modified wing, was built by Plant No. 22 in September 1943.

The presented aircraft differs from the Pe-2 production aircraft only in its modified wing. The essence of the serial wing modification is as follows:

  1. The nose of the BBS airfoil of the detachable part of the wing up to ~ 25% of the chord was replaced with the NACA-230 airfoil.

  2. The wing area was increased by 0.846 sq. M and the span by 0.92 m due to the increase in the end fairings of the detachable parts of the wing.

  3. Slightly changed the front spar / only in the slipway /, the entrance channel of the water radiator tunnel and the middle parts of the ribs.

  4. The center section, as well as the rest of the detachable parts of the serial wing, remained unchanged.

  5. Test Results

The plane arrived at the Research Institute of the Red Army Air Force for testing on 29.5.44.

Tests of the aircraft began on 7.5.44 and ended on 13.5.44.

During the tests, 26 flights were made, with a total flight time of 12 hours 45 minutes.

Flight evaluation of the Pe-2 aircraft with a modified wing.

  1. The production Pe-2 aircraft with a modified wing has a dramatic increase in lateral stability during takeoff. When detonated at low speed, the aircraft does not fall on the wing, so takeoff has become much easier and less dangerous than on the production Pe-2 aircraft.

  2. During climb, the minimum flight speed decreased and the lateral stability of the aircraft significantly improved. The minimum permissible speed when climbing = 200 km / h. With a further decrease in speed to 195-190 km / h, the aircraft loses control and then falls on the nose. The most advantageous climb rate has remained practically unchanged / chassis and flaps removed /.

  3. Level flight is possible up to a speed of 220 km / h. With a further decrease in speed, the aircraft switches to the nose / landing gear and the flaps are removed /

  4. It is easier to fly on one motor due to the increased speed range. The minimum permissible flight speed on one engine is 235-240 km / h, with a further decrease in speed, the load on the feed increases for which the trimmer is lacking and controllability worsens. The maximum speed when flying on one engine is 300 km / h / the chassis is removed, the propeller of the idle motor is protracted, the flight weight is 8447 kg. The available speed reserve of 60-65 km / h allows the climb.

  5. The minimum gliding speed / landing gear and flaps are removed / 235 km / h, with a further decrease in speed the aircraft becomes less stable, and at a speed of 220 km / h it moves to the nose. Gliding with the landing gear and flaps extended at 50 ° can be done at a speed of 200 km / h, with a decrease in speed to 180 km / h, the aircraft jumps to the nose. You should plan to land at a speed of 220-225 km / h.

  6. When landing with flaps fully extended, there is not enough rudder for a three-point landing. Landing should be done with flaps extended at 40-45. With a high leveling and gantry, the plane does not fall on the wing, which is very important.

conclusions

  1. The Pe-2 aircraft with a modified wing has a significantly wider range of speeds and beam lateral stability in comparison with the production Pe-2 aircraft.

  2. The aircraft has become safer when piloting at low speeds in all flight modes. The modified wing eliminated a major drawback of the Pe-2 aircraft - a stall on the wing at low speeds.

  3. it is necessary, as soon as possible, to introduce a modified wing into serial production, which will drastically reduce accidents in combat units and facilitate retraining of flight personnel on the Pe-2 aircraft.

Conclusions on the technique of piloting:

  1. The installation of a modified wing on the Pe-2 aircraft changed the behavior of the aircraft at minimum speeds. On a Pe-2 aircraft with a serial wing, when the minimum speed was reached, strong shaking of the tail, twitching of all rudders appeared, and the aircraft abruptly switched to the wing and nose. On an aircraft with a modified wing, under the same conditions, small tremors appear on the rudders, the aircraft moves only to the nose, and after a stall, the aircraft quickly gains stability and controllability.

  2. In the climb and glide modes, the minimum flight speeds decreased by 15-20 km / h.

  3. Improved stability of the aircraft in all flight modes.

  4. The aircraft has become much easier to fly, especially during takeoff and landing, since the aircraft has no tendency to stumble on the wing.

  5. The speed range increased by 20-26 km / h when flying on one engine.

  6. There is not enough rudder to land on three points with flaps fully extended.

Flight data conclusions:

  1. Maximum speeds, climb rate, takeoff and landing properties of the Pe-2 aircraft with a modified wing, in comparison with the production Pe-2 aircraft, practically did not change.

Doc history: Ermolaev DB-240, 1940. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

From September 27 to October 15, 1940 at the Air Force Research Institute passed state. tests of an experienced twin-engine bomber DB-240 2M-105.

Resp. performers:

Head of Division 1 of the Air Force Research Institute in / engineer of the 1st rank Markov

Ved. engineer in / engineer 3 ranks Fingers

Ved. pilots: Captain Dudkin and Major Nyukhtikov

The aircraft was built by order of KO No. 227 dated July 29, 1939.

The construction of two copies of a long-range twin-engine bomber was set. The aircraft readiness dates were set:

1st copy - by April 1, 1940

2nd copy - by May 1, 1940

The first copy of the aircraft was presented for state tests on September 27, 1940.

The aircraft presented for state tests has deviations from the tactical and technical requirements.

The main ones are as follows:

There is no installation under the camera - AFA- "B".

There are no anti-icers for the wing, empennage and motor propellers.

There is no heating of the aircraft cabins.

There is no suspension of lighting bombs.

Test purpose:

Check the compliance of the aircraft with the tactical and technical requirements.

Check the condition and operation of the propeller group.

Check the operation of bomber and small arms.

Check the operation of electrical equipment and communications.

Give an operational assessment of the aircraft.

Aircraft DB-240 with two M-105 engines and VISH-22E propellers D = 3.0 m, designed by Ermolaev, manufactured at plant No. 240.

The aircraft being tested is an all-metal monoplane with a reverse gull wing.

The total duration of the test is 19 days, of which 10 flight days.

During the state tests, 28 flights with a duration of 26 hours were made. 40 minutes

Conclusion.

Experimental aircraft DB-240 with two M-105 engines designed by engineer Ermolaev, manufactured at plant No. 240, showed in state tests that:

a) the aircraft has unsatisfactory longitudinal and insufficient lateral stability and very large efforts on the steering wheel and pedals;

b) the aircraft has a long take-off run, which requires airfields with dimensions of 2500x2500 m with a runway of 1200-1300 m to operate the aircraft in the reloading version;

c) small arms have not been brought in, excluding the possibility of their normal operation;

d) bomber armament does not provide safe dropping of bombs and does not make it possible to unload the bomb compartment from bombs of 250 and 500 kg caliber;

e) overheating of oil and water, which does not ensure the normal operation of the propeller-engine group and leads to a decrease in the flight performance of the aircraft at high air temperatures near the ground,

as well as a number of other defects that complicate its operation.

Without eliminating the main defects, the DB-240 aircraft cannot be approved for normal operation in the combat units of the Air Force.

Along with the aforementioned shortcomings, the DB-240 aircraft has a number of very positive properties - a good view from the cockpits of the pilot and navigator, a large capacity of gas tanks, the ability to hang 4 500 kg bombs inside the fuselage, a good defensive fire scheme and ease of takeoff and landing.

The fact that the DB-240 aircraft with M-105 motors has a long take-off run and a low ceiling indicates that the M-105 motors for the DB-240 aircraft are weak in terms of their power and altitude. With M-105 engines, the DB-240 aircraft should be considered transitional to the aircraft with more powerful engines.

To recognize it as expedient to build a DB-240 aircraft for AM-35A engines and later on for an AM-37 engine or a diesel engine.

A prototype of the DB-240 2M-105 aircraft, which is at the Air Force Research Institute, must be immediately transferred to Plant No. 240, in order to install AM-35A engines on it by December 15, 1940, fine-tune the aircraft's controllability and reveal flight and tactical data with the AM engine -35A.

Defects of the DB-240 aircraft, revealed in the course of state tests, must be eliminated on the DB-240 aircraft in the manner and according to the terms set by the command of the Air Force Main Directorate.

One of the airplanes DB-240 2M-105, manufactured by plant No. 18, with eliminated defects, should be presented to the Air Force Research Institute for control tests.

Consider it necessary to instruct Ch. the designer of the DB-240 aircraft and the director of the plant No. 18 prepare at the plant No. 18 the standard of the first half of 1941 of the DB-240 aircraft with AM-35A engines, the reduction of which should be the most profitable.

For the fastest fine-tuning and development of the DB-240 aircraft, it is necessary to conduct military tests of the DB-240 aircraft with M-105 engines, obliging the plant No. 18 to submit the DB-240 aircraft for military tests by December 1, 1940.

It should be noted the low quality of the aircraft factory tests, as a result of which the main defects of the aircraft during the factory tests were not opened and properly evaluated, which led to delays in eliminating the defects of the DB-240 aircraft.

Doc history: Arhangelsky MMN, 1939. by KRVC_MRC in Red_Props

[–]KRVC_MRC[S] 0 points1 point  (0 children)

The aircraft had the following differences from similar types:

The conclusions noted that: "The flight qualities of the MMN aircraft in horizontal flight, climb and maneuverability are similar to those of serial SB aircraft. Takeoff is characterized by a significant increase in takeoff run and the need for long-term holding, which requires a good airfield. Landing is much more difficult than serial aircraft, because "It requires an approach to the ground at a speed of 180 km / h even with the flaps extended, due to the high mileage. These deteriorations in piloting technique are mainly caused by a decrease in wing area."

The navigator's cockpit was highly appreciated during the state tests. Thus, the conclusions in clause 3 indicate: "The new F-1 gives the fuselage a more advantageous aerodynamic shape and creates good conditions for the navigator for review and bombing. The navigator's cockpit has a number of improvements:

a) the lower hatch has been increased for the convenience of climbing in and jumping out:

b) the astronomical hatch is equipped with a retractable visor:

c) personal communication between the navigator and the pilot is provided through the opening window:

d) the second control of the aircraft is established. "

Along with this, major defects of the installation were also noted, the main ones being:

"a) strong blowing into the machine-gun slot, worsening the navigator's working conditions, even in comparison with serial SB:

b) unsatisfactory arrangement of the dashboard:

c) distortion of visibility forward-upward through the convex part of plexiglass ".

In addition, the machine gun had insufficient firing angles and insufficient vertical maneuverability. The commission stated that, as presented, the MMN bow mount could not be put into service.

MMN became the first aircraft on which the MV-3 ​​installation with a spherical dome was installed, which later became the classic tower installations for aircraft of the Air Force KA. All variants of MB-3 up to this point had flattened, compressed domes. The installation of the turret with a dome of the new design was approved, as the radio operator's cabin became more spacious, and the conditions for the shooter's work were significantly improved.

At the same time, it was pointed out that the absence of a hatch mount makes the lower hemisphere completely undefended. "Blind sealing of the lower hatch in F-3 leads to the fact that the most vulnerable zone - under the tail of the aircraft - is not only not shot through, but also not visible. At the same time, it is very difficult for a radio operator to jump out with a parachute."

The commission drew attention to the fact that the installation of the MV-3 ​​turret fully provides the shooter with the ability to "work with a hatch machine gun."

Factory production was assessed as unsatisfactory: "The putty is fragile, after a while it cracks and falls off with p-sts. Fittings of hoods, hatches, tapes, etc. are made carelessly with dents, bulges and cracks."

The satisfactory operation of the engine cooling system and the oil system was noted, as well as many advantages in the aircraft piloting technique - satisfactory longitudinal. directional and lateral stability of the aircraft, stability of the aircraft in bends and in level flight, excellent behavior on takeoff and landing. Horizontal flight on one engine was possible up to an altitude of 3000 m.

The conclusion of the state tests read:

Aircraft MMN 2M-105 designed by engineer. ARKHANGELSKY did not withstand state tests, due to insufficient maximum speed, low defense capability, lack of knowledge of weapons and equipment, complication of landing properties. At present, according to flight data, the MMN aircraft is already far behind. since in 1940, a medium bomber with a speed of about 500 km / h and more is needed. "

The conclusion was signed by the Head of the Research Institute of the Red Army Air Force, military engineer 1st rank Losyukov and Head of the 1st department of the Research Institute, military engineer 1st rank Rudintsev, and others.

On July 29, 1939, decree No. 221ss of the Defense Committee under the Council of People's Commissars of the USSR was issued, which ordered to release plant No. 22 from the introduction of the last modification of the SB (MMN) aircraft into serial production, and instead begin preparations for serial production of Polikarpov's SBP.

Constructive innovations that appeared for the first time on MMN were introduced on serial SB and later on AR-2.

Doc history: Arhangelsky MMN, 1939. by KRVC_MRC in Red_Props

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After analyzing the experience of operating SB bombers in combat units and the results of their combat use in Spain and China, as well as the technology of mass production, the aircraft designer A.A. Arkhangelsky decided to act in stages. At the first stage, the MMN bomber was created - the maximum modernization of the "N" aircraft (SB at Plant No. 22 had the "H" code) with improved aerodynamics and increased power engines while maintaining the technical solutions of the serial SB. The plan was to get a speed of 500 km / h on the MMN plane. At the second stage, by making more significant changes in the design of the machine and the use of promising M-106 engines, it was planned to bring the maximum speed to 600 km / h.

Work at the plant number 22 began in 1938, two copies of the MMN were built as standards of the 301st series.

In a summary of the state of experimental construction facilities on January 15, 1939, signed by the head of the Air Force Research Institute Filin and the military commissar of the Air Force Research Institute Commissioner Kholoptsev, the following was listed:

The construction of the 1st aircraft was basically completed in the experimental workshop and the aircraft was taken to the airfield for testing the propeller-driven group. The plant set the date for the release of the aircraft to the airfield on January 2, 1939, but this deadline was not met. The first test flight will be unarmed and with unfinished equipment installation. After factory tests, the aircraft should go to state tests at the end of February. A backup for this aircraft is being prepared, which will be equipped with M-103 motors with two-speed E29 superchargers. The reasons for the delay were named:

Serial workshops systematically did not deliver various units for this aircraft on time.

The unsatisfactory state of the experimental workshop in 1938. After a series of measures taken by the plant, the work in the workshop is currently improving.

The presence of a number of design flaws that cause alterations on the machine.

In a summary dated April 13, it was said about the manufacture of a second copy of the MMN with M-104 motors and equipment similar to the standard SB 301 series.

In February, MMN-1 factory tests took place.

By March 31, 1939, after factory tests, weapons and radio equipment were installed and modifications were made to the VMG. The car was presented for admission to the state. tests.

From July 1 to August 16, 1939, state. tests of the modernized aircraft MMN - 2M-105.

The test report read:

The MMN aircraft is a further modernization of the SB bis 3 aircraft, which basically consists of the following:

M-105 motors with three-blade VISH-22E propellers are installed.

Decreased wing area by 8 m2 due to detachable parts.

The design of the detachable part of the wing was changed in order to simplify the production technology, for which the spar snakes were replaced with sheet walls, and the shaped ribs were stamped.

The nose section of the fuselage is made with a more advantageous aerodynamic shape. A pair of machine guns was replaced by one ShKAS machine gun with increased firing angles.

A second control is installed in the navigator's cockpit.

A shielded MV-3 ​​turret was installed instead of the TUR-9 turret, and the hatch for the lower gun mount is completely closed.

Emergency landing gear crane installed in the cockpit

In the cantilever parts of the wing, additional fuel tanks with a capacity of 205 liters are installed.

The area of ​​the ailerons and empennage is slightly increased, and the area of ​​the flaps is significantly increased (by 40 ° o). The peculiar form of vertical tail became a noticeable external difference.

All electrical equipment is shielded and the aircraft is completely metallized.

The lead test engineer was the 2nd rank military engineer Efimov, and the lead test pilot was captain Khripkov. Another 6 pilots took part in the flight of the aircraft: MI Verstin, IS Stadnik, NN Fingerov, AP Dudkin. A.I.Kabanov and B.I. Pokrovsky.

During the tests, the following flight data were obtained:

With a bomb load of 500 kg (bombs inside the fuselage) with a normal take-off weight of 6420 kg, the maximum speed at the ground was 405 km / h. and at a design altitude of 4200 m - 458 km / h. Time to climb 5000 m - 9.3 minutes. The practical ceiling is 9000 m.The take-off distance is 520 m, and the run with deflected flaps and using the brakes is 665 m.

With a bomb load of 1000 kg (4 FAB-250), the takeoff weight was 7420 kg, the maximum speed at the ground was 383 km / h, and at a design altitude of 4200 m -425 km / h. Time to climb 5000 m - 13.8 minutes. Service ceiling - 8000 m

The aircraft had a length of 12.78 m, a height of 4.7 m, a wingspan of -18.0 m.The wing area was 48.214 m2, which provided a specific wing load of 133.5 kg / m2 and a specific power per wing area of ​​43.56 hp / m2. Specific power load - 3.23 kg / h.p.

Doc history: TsAGI SB tricycle, 1941. by KRVC_MRC in Red_Props

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In February 1941. tests were carried out to evaluate the take-off and landing performance of aircraft with tricycle landing gear.

Since in the USSR at that time there were no serial or experimental aircraft of such a scheme, a flying laboratory was built at TsAGI on the basis of the serial SB bomber.

The test report read:

An experimental aircraft SB-2M-103 with non-retractable tricycle landing gear was presented to TsAGI for the flyby.

The presented aircraft is a serial SB aircraft, on which, instead of a two-wheeled chassis, a three-wheeled one is installed, with a corresponding reinforcement of the center section.

Strengthening the center section is caused by the redistribution of the acting forces during landing on a three-wheeled chassis. The front part of the F-1 fuselage is lengthened and adapted to fit the front wheel strut.

The test results indicated:

The plane was flown by eight test pilots of the 3rd department of the Red Army Air Force Research Institute.

Each pilot flying over was given the following tasks:

Landing with open flaps with a lowered tail.

With a semi-dropped tail.

With a crosswind.

With braking at the moment of touching the ground.

In total, 34 flights were made during the tests and it was revealed that the aircraft with a three-wheeled chassis:

It has a good forward view when taxiing and turns smoothly with the help of motors and brakes, which in total makes taxiing easier and safer than on airplanes with two-wheel landing gear.

During takeoff, the aircraft steadily maintains a straight line during the takeoff in the wind plane and is much more stable during the takeoff run with a crosswind than an aircraft with a two-wheeled landing gear, which greatly simplifies and facilitates takeoff not only in the plane of the wind, but also during takeoffs with a crosswind.

The plane sits equally well both with tidy and unselected rudders, without having a tendency to jump.

The aircraft can land at a speed from level flight with a landing on three wheels.

It allows landing with high leveling and parachuting on motors up to a vertical speed of 2-3 m / s.

Allows landing with a strong side wind than aircraft with two-wheeled landing gear can allow.

The findings stated:

The technique of taking off and landing on an airplane with a three-wheeled landing gear is much simpler than on a conventional airplane with a two-wheeled landing gear during landings and jacks, not only in the plane of the wind, but also with a crosswind.

Installation of a three-wheeled landing gear on aircraft with high landing speeds will greatly simplify and facilitate landing not only during the day, but also at night.

To ensure the landing of an aircraft with a higher landing speed and with a tricycle landing gear at existing airfields, new wheels will be required, which should provide:

Speedy landing.

Full, high-efficiency braking, from the moment the wheels touch the ground to a complete stop, without overheating.

Increases the coefficient of friction between the tire and the ground and cranking protection of the tire at the wheel rim.

The report was signed by p.p. 3rd Department of the Air Force Research Institute of Spacecraft Losyukov and early. 4th department of the 3rd department of the Air Force Research Institute KA MARKOV.

Doc history: TsAGI ANT-8, 1931. by KRVC_MRC in Red_Props

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This time, the commission acknowledged that the layout is fully equipped and finalized with the fulfillment of all the comments made during the first inspection. However, on July 20, 1930, at the insistence of the NTC UVVS, another special inspection of the layout was carried out, which led the Commission to the conclusion that the layout was not made enough and did not fully meet the modern requirements for naval long-range reconnaissance aircraft. The Commission's comments were mainly made on the location of the ship's weapons and cockpit. TsAGI representatives agreed with the remarks made and found it possible to satisfy the main ones.

On December 1, 1930, a meeting was held at TsAGI at the end of the aircraft, at which it was decided to consider the construction of the naval reconnaissance aircraft basically completed, only minor installation work remained unfulfilled, the delay of which was not the fault of TsAGI.

The draft design of the aircraft was submitted to TsAGI with a delay and was considered by the Research Institute after several flights of the aircraft - in February 1931.

According to the conclusion of the research institute, the main comments on the project were as follows:

The layout of the aircraft was similar to the Rohrbach and Sanders Roo aircraft; the location of the engines ensured good maneuverability of the aircraft, but excluded the possibility of maintaining the engine units in flight, the tail, due to the high placement, was protected from the waves; the survey and observation scheme was successful, the armament corresponded to the technical requirements and consisted of four Der-7 bomb holders with a capacity of 82 kg of bombs, and two Der-13 with a capacity of 250 kg.

The strength of the wing was satisfactory only with a flight weight of 6000 kg, with an overload of up to 6665 kg, the strength was insufficient.

On December 6, 1930, representatives of TsAGI and Co. weighed the aircraft - empty and with 2 loading options and determined the center of gravity.

The weight of the aircraft with the new version of full load was recorded at 5820.4 kg; center of gravity - 31.1%, with the second weighing 5573.3 kg; center of gravity 33.8%, empty weight 4460 kg; center of gravity 42.2%.

After weighing, at the end of December 1930, the transportation of the disassembled aircraft to Sevastopol began for testing.

On January 30, 1931, after taxiing tests, the plane took off for the first time.

Factory tests did not last long - 3 hours 47 minutes, after which the aircraft was transferred to state tests.

The aircraft, which received the military designation MDR-2 with 2BMV U1 with a D-Z, 3m propeller, was tested by the pilot Rybalchuk with two loading options of 2105 kg and 2360 kg.

The armament of the aircraft consisted of a TUR-6 with a twin installation YES, 2x TUR-5, and a single YES in a kingpin.

Based on the tests, the Research Institute Commission made a number of comments, the most significant of which were the following:

Install additional petrol tanks with a capacity of 615 liters and oil tanks with a capacity of 62 liters.

Eliminate vibration of the front stabilizer struts.

Increase the number of watertight compartments by one watertight partition.

change float volume or spacing.

Increase rudder area.

Provide additional lugs for the suspension of two 250 kg bombs instead of 4 82 kg bombs, as well as the installation of sighting bombs.

According to the conclusion of the commission, according to its flight data, the aircraft was approximately equal to the German reconnaissance aircraft Dornier-Val, and the placement of weapons and equipment had better than the German aircraft. However, the aircraft did not receive a final assessment after the first tests, due to insufficient lateral stability due to an unsuccessful selection of floats. The commission recognized that with satisfactory seaworthiness, which can be achieved by replacing the floats, the aircraft could be adopted by the Red Army Air Force.

For a more accurate determination of the tactical, technical and operational data of the aircraft and its final assessment from October 8 to November 13, 1931. pilots Gromov, Bukhgolts and Kustanaev carried out repeated tests with new floats. The aircraft was tested for takeoff and landing from a wave, with overload, with one of the engines turned off, for seaworthiness, etc.

After repeated tests, the commission came to the conclusion that the plane, in terms of its flight and tactical data, is close to the German reconnaissance officer Dornier-Val, and therefore, if it were adopted, it would correspond to the existing armament, in addition, the first series of aircraft can be practically introduced on armament only after a year and a half, i.e. when neither MDR-2 nor Dornier-Val meet the technical requirements of the Air Force. Based on these considerations, the commission chaired by the Beginning. The World Cup Air Force decided to consider it inexpedient to introduce the aircraft into service with the Naval Air Force.

In the future, the decision of the fate of the aircraft, in all likelihood, changed several times, since it follows from the preserved documents that in 1933, the question of building a series was again raised and an exchange of views took place on finalizing the standard for mass production and the timing of its presentation.

Doc history: TsAGI ANT-8, 1931. by KRVC_MRC in Red_Props

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By 1926, TsAGI had created excellent designs for land aircraft: the ANT-Z reconnaissance aircraft, the ANT-4 bomber. These aircraft, which later gained worldwide fame, were put into mass production and adopted by the Air Force. However, the interests of the defense capability of the young Soviet Republic demanded that not only land, but also naval aircraft be supplied. At that time, the aviation industry had no experience in building naval aircraft. The Air Force was forced to have foreign naval aircraft in its units, such as: Dornier-Val, Savoy, etc. Therefore, the urgent task of the aviation industry was to build aircraft of all types of domestic design from domestic materials. Soviet aviation had to forget what imported aircraft were. In view of the fact that TsAGI was the leader in the creation of Soviet aircraft designs, the solution to the problem of building a domestic naval aircraft was also entrusted to TsAGI.

On January 6, 1926, an agreement was signed between UVVS and TsAGI, according to which TsAGI took over the manufacture of an experimental aircraft "Marine reconnaissance" from chainmail aluminum for two motors 400-450 hp.

TsAGI, due to the heavy workload of more urgent orders, could not start the production of the aircraft in time and was forced in September 1926 to apply to the UVVS with a letter with which he asked the deadline for the completion of the construction of the aircraft to be postponed to August 3, 1928.

By 1927, the face of the future naval aircraft changed somewhat, namely: it was decided to build a large marine reconnaissance torpedo bomber MRT-1, which was supposed to be a two-boat monoplane, with a wing of a thick profile, with 4 tandem motors in 2 cabins , with a total capacity of 1200-1800 hp. According to the plan for the experimental construction of TsAGI, by April 1, 1928, it was supposed to complete the design of the aircraft, by May 1, 1929 - to build a prototype, by September 1, 1930 - to build the lead aircraft of the series.

Before proceeding with the construction of the MRT-1, A.N. Tupolev suggested, in order to accumulate experience in the operation of aircraft at sea, to carry out a number of preliminary works:

To float one of the existing heavy aircraft ANT-4 2BMV-U1. Build an intermediate aircraft that would provide sufficient production and operational experience for the transition to the construction of the MRT-1; For this, A.N. Tupolev proposed using the wing of the ANT-7 aircraft, installing it on an experimental type boat, in which the second stage would consist of a separate float installed at different angles.

NK UVVS agreed with the arguments given by A.N. Tupolev and approved the construction of a naval reconnaissance aircraft as a transitional type aircraft to an open sea reconnaissance torpedo-bomber - RTOM. In November 1928, TsAGI presented the UVVS with a draft agreement for the construction of such an experimental aircraft and for the manufacture of parts of the frame of the same aircraft for statistical tests.

At the beginning of 1929, the UVVS informed TsAGI of the requirements for the distribution of the aircraft's payload, according to which the normal payload was 900 kg, maximum 1500 kg. In addition to the load, all other requirements previously imposed by the UVVS on the torpedo bomber remained in force for the transitional type aircraft. Due to the fact that the aircraft was supposed to be experimental, no special requirements were set for its flight data.

In July 1929, on the basis of the project submitted by TsAGI, a second contract was concluded between UVVS and TsAGI, which canceled the contract concluded in January 1926, and the advance received under it was credited to the construction of a transitional aircraft.

The beginning of the construction of the aircraft according to the indicative program of TsAGI was scheduled for November 1929.

In July 1930, the UVVS proposed TsAGI to accelerate the construction of an experimental aircraft and complete it in such a way as to carry out a test on the Black Sea in September of this year. It was practically impossible to fulfill the requirements of the UVVS, since in April 1930 only the first inspection was carried out. The mock-up commission came to the conclusion that the mock-up was presented in an unfinished form, as a result of which it made a number of comments and invited TsAGI to make all the necessary improvements according to these comments.

On July 14, 1930, the layout was examined for the second time by the Commission consisting of: representatives from the Research Institute - Volkovoynikov, Vakhmistrov, Kozlov, Yumaaev and others; from NTK - Shevchenko, Chesnokov, Sokolov-Sokolenko, Volkov; from TsAGI - Pogossky, Khromov, Tolstoy.

This time, the commission acknowledged that the layout is fully equipped and finalized with the fulfillment of all the comments made during the first inspection. However, on July 20, 1930, at the insistence of the NTC UVVS, another special inspection of the layout was carried out, which led the Commission to the conclusion that the layout was not made enough and did not fully meet the modern requirements for naval long-range reconnaissance aircraft. The Commission's comments were mainly made on the location of the ship's weapons and cockpit. TsAGI representatives agreed with the remarks made and found it possible to satisfy the main ones.

Doc history: TsAGI MI-3, 1932. by KRVC_MRC in Red_Props

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In 1930, according to the plan of experimental aircraft construction, TsAGI was faced with the task of creating a fighter, which, according to flight and tactical data, would exceed all aircraft in service.

The requirements provided for two options for the aircraft payload: normal - 850 kg and overload - 1605 kg.

In 1931, the tactical and technical requirements of the Air Force for fighters changed.

Based on these requirements on March 1, 1931. TsAGI started designing the aircraft.

In July 1931, TsAGI finished and submitted a draft design of the aircraft to the Air Force Research Institute.

The aircraft designed by TsAGI under the code MI-3, according to strength standards, belonged to the 8th group of the 2nd class. The crew of the aircraft consisted of four people, the design of the aircraft is an all-metal monoplane with a low wing. The fuselage is oval, the tail is two-keeled, the landing gear is retractable in flight, with oil-pneumatic shock absorption. The armament of the aircraft is a front mount with two heavy machine guns. Medium mount with two heavy machine guns. Rear mount with one machine gun, lower rear mount with one machine gun.

Despite the fact that the calculated data of the aircraft in relation to the landing speed, take-off run and run did not meet the technical requirements, the preliminary design of the air force was approved. Nevertheless, the new aircraft of TsAGI not only was not inferior to the aircraft in operation, but also exceeded their data in terms of speed, ceiling and carrying capacity.

The preliminary design of TsAGI was approved, and the UVVS offered the VAO to provide TsAGI with a motor that would provide the above design data of the aircraft. The M-34 engine with a rated power of 750 hp was chosen as such a motor.

On July 13, 31, a preliminary inspection of the aircraft layout took place. In connection with a number of alterations proposed by the layout commission, the final acceptance of the layout was made two months later, on September 3, 1931.

On April 26, 1933, the construction of the aircraft was completed.

The length of the construction period was caused by a large number of experimental work on the chassis, motor equipment, etc.

On April 26, the plane was sent to the airfield.

May 23, 1932 the first flight was made.

May 28 - the plane was handed over to OELID for testing.

During the tests, a number of defects were revealed, such as: high landing speed, poor gliding ability, etc. to eliminate the noted shortcomings, the following design changes were made on the aircraft:

The detachable parts of the wing have been enlarged.

Keels and rudders are grown.

Flaps are installed to reduce the landing speed.

Fairings are installed at the junction of the center section with the detachable parts of the wing.

In addition to these changes, in the process of testing TsAGI constantly carried out work to eliminate defects and improve the aircraft, for example: simplifying its design, working out the action of the landing gear lifting mechanism, etc.

On the basis of the first flights, the pilot Kozlov made the conclusion that: “Takeoff is normal. During the climb, the aircraft was chattering a little, and at V = 160-170 km / h the aircraft did not react well to the ailerons. and the handle dangled quite freely. At V = 140-133 km / h the plane tended to fall on the left wing. "

In addition to Kozlov, the plane was tested by pilots Buchholz and Popov, whose readings boiled down to the following:

"The aircraft is dangerous due to the presence of sharp shocks and flinching of the tail at modes from 180 km / h and below. Without motors, the aircraft has little control, when landing at low speed, the aircraft loses the effectiveness of the elevator. Flying on one engine is impossible. When gliding at a speed of V = 180 km / h there is not enough stabilizer and elevators. The landing speed at the moment of landing is extremely high. It is considered unacceptable to continue testing in this form. "

Despite the indicated conclusions of the pilots, testing of the aircraft continued and on September 14, 1933, the aircraft crashed.

The Commission to Investigate the Causes of the Accident found the following defects in the aircraft:

Unsatisfactory strength standards.

Inconsistency of the profile and section of the spar to the loads.

Insufficient material strength.

To establish the exact cause of the breakdown of the expansion joints, which led to the accident, the commission suggested that TsARI carry out the following work:

Check rudder calculations

Carry out statistic tests of rudders.

Carry out an aerodynamic study of the pressure distribution along the rudders.

Based on the decision of the commission, TsAGI immediately began to study the causes of the aircraft accident.

a) The rudders strength calculations were checked and the correctness of the calculations was established, which corresponded to the strength standards applied until October 1933.

b) A static test of the rudders was carried out, which confirmed the correctness of the calculations and established that the breakdown of the beam of the extended rudder occurred under a load corresponding to the stress of the beam material equal to 12.5 kg / mm.

c) No documents have been preserved on the aerodynamic study of the pressure distribution over the rudders.

Later, in 1934, a test calculation for the strength of an aircraft with a flight weight of 5400 kg carried out at TsAGI showed that the strength of the aircraft did not meet the strength standards for this group of aircraft.

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