5 (airplane)

"5"
"5-1" during testing under a Pe-8
Type:	Experimental airplane
Design country:	Soviet Union
Manufacturer:	Bisnowat
First flight:	July 14, 1948
Number of pieces:	2

The aircraft "5" was an experimental aircraft with rocket propulsion and swept wings, built in only two copies .

history

The project began in the spring of 1945 under the direction of M. R. Bisnowat . The aim was the experimental research into the flight in the supersonic range , since there was no experience, only theories, which should be checked. A lack of knowledge about the shock waves occurring in the vicinity of the sound and other effects had e.g. B. led to the crash of the Soviet Bolchowitinov BI-1 , but also various US X aircraft . With the airplane “5” the advantages of the swept wing should be checked. The project was created at the same time as the DFS 346, which was later captured by the Soviet Union, and the Douglas D-558-II Skyrocket. Although all three projects were carried out completely independently of one another, similar solutions and results were found in many details.

The aircraft "5" was an all-metal mid - decker with a two-spar swept wing (45 ° sweep in 25% profile depth). The wing profile was chosen according to the ZAGI recommendation . At the root it was a ZAGI 12045bis and at the end a P2 (2M). The biggest design flaw of the German DFS 346 was avoided, because the DFS 346 had the same profile over the entire span, which could lead to a sudden break in the flow on the entire wing and thus to a complete loss of lift. The lack of knowledge about swept wings was also evident on the German side. In the case of the "5", two boundary layer fences were arranged on each wing top to prevent an early stall at the wing end. In the right wing there was a row of measuring bores on three cross-sections to determine the pressure conditions. The fuselage had an upright oval cross-section and a fuselage separation point, which enabled the assembly of the drive and the fuel tanks. In the front part of the fuselage there was a pressurized cabin with an ejection seat. The canopy was designed to conform to the fuselage and did not protrude above the fuselage. The ideal spindle shape could be retained (as with the DFS 346 and the first version of the Douglas D-558-II). Brake flaps were installed in the rear of the fuselage, and a two-chamber liquid rocket engine RD-2MSWF designed by L. S. Duschkin was installed in the stern . At heights above 8000 m, the thrust was 19.6 kN, near the ground 15.8 kN. Fuel was kerosene, nitric acid and hydrogen peroxide. The fuel supply was designed for two minutes at the maximum output of both combustion chambers.

The hydraulic control was something completely new and also had a few extras. This made it possible to steer the aircraft by adjusting the entire horizontal stabilizer if the elevator was not effective. The pilot could switch this on to the control stick. The pilot was also able to switch off the feedback from the controls. This meant that he was no longer given any steering forces on the joystick and enabled him to use very high steering forces in an emergency.

The take-off should be from a carrier aircraft. Therefore, the landing gear was reduced to a landing skid, the tail skid and reinforced edge arches at the wing ends. The carrier aircraft was a Pe-8 , on which the "5" was hung under the right wing between the fuselage and the first engine pod. To test the "5", models with autopilot were built and thrown from a Tu-2 and tested. A single-chamber liquid rocket engine U-400-10 developed by A. M. Issajew with a thrust of 400 kp at an altitude of 10 km was used for the models . Many values ​​were flown with the models. For example, the resistance curve up to Mach 1.45 could be recorded.

An unpowered test flight of the original should take place according to the following pattern: release from the carrier aircraft at an altitude of 7000–7500 m, dive to catch up, transition to level flight with 2 to 3 g load multiples , delay until stalling and another dive. From an altitude of 1500 to 2000 m, the program should be ended and the flight home should be started.

A test flight with rocket propulsion should propel the "5" to a speed of approx. 1200 km / h and at altitudes of 12 to 13 km (Mach 1.13). However, calculations showed that much higher speeds and heights would be possible. This also coincides with the American Douglas D-558-II, which was designed for Mach 1.4 and reached Mach 2.01.

Test flights

Since two planes were built, they are often referred to as "5-1" and "5-2".

The "5-1" was flown as a glider for the first time on July 14, 1948 by test pilot A. K. Pachomow. There were problems separating the machine from the carrier aircraft. The "5-1" was damaged and only managed one outlanding, during which the machine suffered further damage. The longitudinal steering also caused problems. After the repair and conversion of the drop device, two more unpowered flights took place, during which the control system, which was also converted, now worked perfectly. However, the aircraft showed an unfavorable relationship between lateral and course stability. This was one of the causes of the accident at the end of the third test flight. The plane hit the ground with one wing first, then the other. In the end it almost overturned and was largely destroyed in the process. The pilot was uninjured, but it was no longer possible to repair the aircraft.

In January 1949 the "5-2" was completed. It differed in details from the "5-1". The extension and sweep of the vertical stabilizer was increased to improve directional stability. On the recommendation of the ZAGI, the end arches at the wing ends were replaced by feather spurs.

The first flight of the "5-2" on January 26, 1949 under Georgi Schijanow ended again with an outside landing. This was also due to the aircraft, which the pilot was unfamiliar with, and the short runways of the LII. The plane was damaged. During the repair, the aircraft was rebuilt. The landing skid was designed so that the tail skid could be dispensed with. At the stern, space was created for the assembly of a false keel , which should further improve directional stability.

The next flight went smoothly, but showed that the necessary relationship between lateral and directional stability could still not be achieved. Normally one would address this problem by changing the V-position of the wing. But that was not possible because the wings were inseparable from the fuselage. Therefore it came to the assembly of "fins" on the wing outer edges. These had the same profile as the wing and were directed downwards at an angle of 45 °. With this version Georgi Schijanow completed six more gliding flights in June 1949, in which speeds of Mach 0.775 were reached. The mass of the aircraft was 1710 kg. The aircraft impressed on these flights and the controls also proved their worth. The aircraft was ready for a self-propelled flight. However, this never happened for unknown reasons.

Technical specifications

Parameter	Data
crew	1
length	11.20 m
span	6.60 m
height	2.40 m
Takeoff mass	1710 kg
Top speed	Mach 0.775
Engine	a two-chamber liquid rocket engine RD-2MSWF with a thrust of 19.6 kN at 8000 m and 15.8 kN near the ground
fuel	Kerosene, nitric acid and hydrogen peroxide (the drive was never used)

literature

• K. J. Kosminkow: "Skyrockets" with the red star . In: Peter Stache (Ed.): FR-Edition . No. 02 . Fliegerrevue, Berlin 1993.

Web links

• Illustration on Modeling Madness ( Memento from April 26, 2010 in the Internet Archive )

Individual evidence

1. ↑ XII. Le Bisnovat 5. In: xplanes.free.fr. Retrieved February 15, 2020 (French). 
2. ↑ Bernd Heller: Aircrafts "5-1" & "5-2". modellversium.de, January 4, 2011, accessed February 15, 2020 .