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Bisnovat 5
 
 Bisnovat-5-01
Bisnovat "5" in the TsAGI before the modifications.
 
The Bisnovat 5 experimental aircraft was developed in 1948 with the aim of testing the influence of the 45º swept wing on the range of supersonic flight speeds. Two prototypes were built and tested in a glider configuration due to difficulties in setting up the selected power plant.
 
Based on the concept of the DFS 346, the Bisnovat “5” featured an overall configuration similar to that of the Bell X-1, which would be the first manned aircraft to break the sonic barrier.
 
The effectiveness of wing sweep in achieving high flight speeds was demonstrated at the end of the 1940s. The 35º swept wing did not allow to overcome the sonic barrier, as it generated too much resistance. The calculations showed the need to test a new wing with 45º sweep and increase the engine power.
 
In the TsAGI they developed a wing with these characteristics, but the T-106 wind tunnel did not allow it to be tested at speeds above Mach 0.9. This required the construction of experimental aircraft.
 
This happened at the end of 1946, when in the former premises of the main constructor Boljovitinov, in the Factory No. 293 of the MAP a new OKB was created at the head of which was MR Bisnovat located. This new OKB was tasked with developing a supersonic experimental aircraft in order to test characteristics in flight and piloting conditions at speeds of Mach 1.1.
 
The aircraft received the designation “5” and had to be built according to an aerodynamic composition based on the 45º swept wing and TsAGI 12045bis and P2 (2M) profiles. Its development was carried out in parallel with the tests by OKB-2 of the captured German DFS 346 aircraft. The powerplant selected was the Dushkin RD-2MZVF liquid reactive engine capable of developing 2000 kg of thrust and was conditional on the fact that a higher power engine did not exist in the USSR.
 
Due to the low capacity of the engine, the ascent to a height of 10,000 meters had to be done by a mother plane. Once this height was reached, the plane released and the rocket engine was started. The calculations showed that, in addition to a speed of Mach 1.1, the "5" would reach 15,000 meters (from 10,000 m) in just 68 seconds. The duration of the flight with full power would be only 2.5 minutes.
 
The development task was officially approved in a new experimental construction plan that was signed on March 11, 1947.
 
The “5” was conceived as an all-metal monoplane with a double spar mid-set wing and 45º taper along the 25% chord line. The wing profiles were suggested by TsAGI : TsAGI 12045bis in the wing root and P2 (2M) in the extremities. The wingspan reached 6.4 m. Two aerodynamic fins were installed on each console on the upper wing surface to break the flow. In order to study the pressure distribution throughout the wing at high speeds, drains were made in three sections in the right wing.
 
The monocoque-type fuselage had an oval section and a length of 9.92 meters. The front part consisted of a sealed cabin. Flying in an airplane at high speed implied a high risk, so the cabin was designed in such a way that in emergencies it was separated from the rest of the plane. The transparent cover was aerodynamically inserted into the fuselage. Behind the wing, on both sides of the fuselage, aerodynamic brakes were added.
 
In the tail section was located a reactive double chamber RD-2M-3F engine, designed by LS Dushkin with a power of 2000 kg at 8000 meters and 1610 kg of thrust at sea level. The chemicals (kerosene and nitric acid) and hydrogen peroxide (for turbocharger feed) were calculated for a flight time of about two minutes at full power.
 
As the "5" aircraft was designed to be launched from a mother plane, the landing gear consisted of a ski located in the lower part of the fuselage, two stabilization supports on the wings and a small skid on the tail section.
 
The high tail had sweep. The stabilizer had a span of 2.4 meters. The aircraft could be controlled using the stabilizers, which were connected to the flight stick. Boosters could be connected to reduce the pressure on the stick.
 
In order to guarantee the necessary safety, it was decided to first carry out the tests using a scale model that was called “6” and designed with full flight capacity. The "6" was built in factory 293, in conjunction with the OEZ TsAGI led by Kuznietsov. This model was built at 1: 2.75 scale, and equipped with a liquid reactive U-400-10 engine with 400 kg of thrust manufactured by Isayev and had an AP-14 autopilot system.
 
The "6" model had to be towed by a Tupolev Tu-2 bomber up to a height of 9000 meters and after detaching it had to connect the reactive engine to reach a supersonic speed of Mach 1,225 in straight flight. To record the flight data the "6" was included in the model a data recording system.
 
The recovery of the "6" was carried out by means of parachutes operated in sequence. Initially, the braking parachutes located on the wings were opened, with an area of ​​1 sq.m. Later the main braking parachute located in the tail area and with an area of ​​100 sq.m was opened.
 
In total, 4 examples of the Model "6" were built and tested in September - November 1947, at Gumpak airfield, near Stalingrad.
 
The first model (No.61) after the detachment quickly moved away from the Túpolev Tu-2, reaching great speed. The following La-7 soon lost sight of the model and it was never found.
 
The second model (No.62) after detaching began to present large oscillations around the axles and this resulted in the engine turning off with only 8 seconds of work. The model opened its parachutes and could be recovered without problems. The recorded speed was only 230 - 240 meters per second.
 
The third model (No.63) worked without problems, but after 44 - 45 seconds of flight, it plummeted and the brake parachutes were pulled away. The model was launched towards the ground, burying itself at a depth greater than 3 meters. During the impact the search equipment was badly damaged and some could not even be found in the metal mass. According to the measurements obtained from an MS-7 team and assuming that they were taken during the flight in a straight line at 8,300 meters, a speed of 1405 km / h (Mach 1.28) could be calculated.
 
The fourth model (No.64) flew without problems for 51 - 52 seconds, presenting only some oscillations in relation to the transverse axis. After the engine finished working, the main parachute did not open, so that only with braking the model began to descend, burying itself about 80 centimeters into the ground. In this case it was possible to recover the result of the measurements of the recording equipment, which yielded a model speed of 1230 km / h (Mach 1.11)
The figures obtained allowed the MAP to consider that the speed of the models corresponded to that calculated and to consider the tests as successful, but the direction of the VVS disagreed. Bershinin wrote in January 1948 to the Minister of the Armed Forces NA Bulganin:
 
“ In relation to the tests with the help of the Bisnovat manufacturer's models, we can deduce that as a result of their lack of completion as aerodynamic models and the lack of objectivity of the flight data, objective conclusions cannot be made and they can only be considered as a first step in the use of flying models in the investigation of high flight speeds. "
 
The need to develop a dozen "6" models and repeat the tests ensuring the preservation of the recordings of the measuring instruments was strongly discussed. This never took place because very soon the first prototype of the plane "5 " was ready which was known as "5-1".
 
 Bisnovat-5-02
The first prototype "5-1" during testing.
 
The first prototype with full flight capacity was named " 5-1 ". The towing system was replaced by the under-wing attachment of a mother aircraft, in this case a Petlyakov Pe-8 (No. 4291) with Ash-82FN engines, which was specially prepared for this task. Under the right wing, between the fuselage and the inner engine console and installed a special bracket from which the " 5 " was hung. The launch was carried out at heights of 7000 - 7500 meters. The weight of the plane in glider configuration reached 1565 kg.
 
The delivery of the engine suffered delays, reason why the first " 5-1 " sample began to be tested in July 1948 in a glider configuration, in order to check the behavior of the aircraft at low speeds. The “5” plane was flown by Colonel Pajomov and the Pe-8 mother plane by test pilot MA Samusiev and Ziemskov.
 
The flight plan included a dive after detachment, with departure to horizontal flight with an overload of 2 -3g, increase in speed until the plane reached 1500 - 2000 meters in height, when the tasks stopped and the plane was preparing for landing. During the landing, the behaviour of the plane at low speeds was studied.
 
In the first flight the 14 of July of 1948, there was a rending of the alar coating at the time of the release of the mother aircraft, affecting directional stability. The pilot managed to control and land the plane, but off the runway. The " 5-1 " was damaged and was sent to the factory for repair.
 
During this process some modifications were made. To prevent the plane from hitting the mother plane again at the time of detachment, the fixation system was modified. The flight control system was modified.
 
 Bisnovat-5-03
Rear view of the Bisnovat "5-1".
 
The second flight on September 3 was quite positive, but it showed a lack of transverse stability and the lack of effectiveness of the ailerons to correct it. It was decided to study this phenomenon in depth on the third flight on September 5, but another accident occurred during the landing. Upon landing the plane hit the ground with one wing, then the other. The pilot was unable to control the landing and ended up burying his nose, which caused the destruction of the plane. The pilot was unhurt but the plane could not be rebuilt.
 
 Bisnovat-5-04
Prototype "5-1" destroyed after its third flight.
 
The commission created to analyze the accident was headed by the replacement of the head of the TsAGI laboratory, VN Matvieyev. It was found that the cause of the accident was the lack of lateral stability of the plane at low speeds after extending the landing pad and the increase in resistance in the aileron control system; as well as the incorrect ground connection and the deterioration of visibility due to the condensation of water vapor that appeared on the cabin cover. It was recommended to build a second specimen taking into account the recommendations recorded and to modify and test the landing system at TsAGI.
 
These accidents delayed the obtaining of the expected results in "5". In 1947 at the request of the VVS and with the support of the Moscow committee of the CPSU, the MAP was directed to carry out the necessary actions to equip the TsAGI with wind tunnels capable of testing the new speed environments. In the second half of that year, the new T-112 tunnel began to operate at TsAGI.
 
 Bisnovat-5-05
Drawing of the prototype "5-1"
 
The dimensions of the work area of ​​this tunnel was not large, measuring only 0.7x0.6 meters, but the flow velocity reached Mach 2. This tunnel still lacked the necessary instrumentation to carry out the measurements, but it was considered that it was enough to determine the effectiveness of the wing at 45º.
 
A second " 5-2 " prototype was built and ready by January 1949. It was practically no different from the first prototype, but to improve directional stability it was lengthened and increased the sweep of the vertical fin, which led to an increase in the length of the aircraft to 11.2 meters. The stabilization wing supports for landing were replaced by amortized skids capable of absorbing energy during impact with the ground.
 
 Bisnovat-5-06
Drawing of the prototype "5-2"
 
It was first decided to continue the tests in a glider configuration. The LII test pilot G. M. Shiyanov was selected as the pilot. The Pe-8 mothership was piloted by Gintsie and Chistyakov.
 
Between 26 January and 9 of June of 1949 the " 5-2 " carried out a total of nine glider flights, in October-November four, none with engine, even though it had been installed on the model and tested on the ground.
 
During the tests the weight of the aircraft reached 1710 kg, the maximum speed obtained in the dive flights reached Mach 0.775. The plane showed good behaviour and the flight control with the help of hydraulic boosters was practically no different from the conventional one.
 
Despite the promising results, everyone understood that the " 5 " had lost its "moment". Reactive engines, characterized by their dangerousness, short working time and capricious behavior, now gave way to the increasingly capable turbojets, which had already demonstrated their ability to reach sonic speeds. The MAP leadership, in this situation, decided to turn its back on the project and, without much explanation, stopped financing it.
 
During the tests of the “5” for the first time in the USSR , the launching test system for rocket aircraft from the wing of a mother aircraft was tested and the accumulated experience was of great use for the development of new types of aircraft and missiles.
 
On the basis of the aircraft “5” Bisnovat and Isayev developed the air-surface missile R-1.
 
 Bisnovat-5-07
Drawing of the Bisnovat "5"
 
"5"
Powerplant: 1 RD-2M-3VF liquid reactive, 1610 kg thrust
Wingspan: 6.40 m
Length: 9.92 m
Wing area: 11.18 m²
Empty weight: 883 kg
Maximum takeoff weight: 3184 kg
Wing loading: 95.6 kg / m²
Maximum speed: 1200 km / h
Accommodation: 1
 
 Bisnovat-5-08
Views of the different variants of the Bisnovat "5".
 
 
 
 
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