The Soviets had been experimenting with bipropellants rockets since 1929. In 1935 the RNII research institute had developed the ORM-12a rocket engine, with 400 kg peak thrust, to use as a take-off booster of the Tupolev TB-1 bomber.
The RDA-1-150, capable of producing 150 kg peak thrust burning a mixture of kerosene and acid nitric, was tested on February 11, 1939.
The new engine was throttleable and it was decided to use it as a power plant for an SK-9 glider as flying testbed. The prototype, named Korolev RP-318-1, was flown on February 28, 1940, reaching 140 km/h and 2,900 m with 110 seconds engine running.
After learning about the performances of the high-altitude Junkers Ju 86 P-1 reconnaissance airplane, the GKO authorized the use of rocket engine propulsion system for high-performance fighters.
After the German attack, several designs for potential rocket interceptors eventually came to be created in the Soviet Union.
Undoubtedly the smallest fighter in the history, similar to the German Bachem Natter, a project was conceived by the military engineer Lev Golovin in 1941, based in the aerodynamic and rocket propulsion principles of Konstantin E. Tsiolkowski. It was designed in two versions:
The ‘IVS’ (Istrebitel Voyskovogo Soprovozhdeniya) version for the Soviet Air Force was designed for the target defense of factories, communication nodes, refineries and headquarters. The ‘IVS’ was launched from a 40-degree truck ramp with 8 m length, helped by two solid fuel rockets. The launching team was formed by the pilot, the mechanic, and the truck driver.
The ‘ISF’ (Istrebitel Soprovozhdeniya Flota), the naval version, was designed for the target defense of the naval bases and warships.
The mass production of the Golovin fighter was rejected in favor of the conventional antiaircraft artillery.
Technical data
Type: VTO rocket interceptor, structure and cladding: light alloy, landing gear: retractable skid and brake-parachute with 9.39 m of diameter, engine: one Dushkin/Glushko RD-1 bi-propellant rocket with 300 kg thrust and two RATO solid fuel rockets with 1,000 kg peak thrust each, propellant tanks were mounted to both sides of the pilot containing nitric acid and kerosene in a ratio of 2 to 1 (probably 70 lt. of acid and 30 lt. of kerosene, pressurizer: nitrogen, armament: one 20 mm ShVAK cannon, wingspan: 5.74 ft. (1.75 m), length: 9.48 ft. (3 m), height: 3.4 ft. (1.05 m), wing surface: 11 sq. ft. (1 sq. m), maximum weight: 662 lbs. (300 kg), estimated maximum speed: 659 mph (1,060 km/h), estimated climb rate: 820 ft./second, estimated ceiling: 24,600 ft. (7,500 m).
During ground test conducted in the spring of 1941, the Dushkin-Isayev D-1A-1100 acid/kerosene rocket motor produced 1,100 kg peak thrust.
To achieve that power, the engine used fuel pumps that suffered serious corrosion problems due to acid, which could not be solved. It was necessary to reuse the old pressurization system by compressed air, thus reducing the powered endurance to just 15 minutes.
In June 1941 it was decided to use the D-1A-1100 for the propulsion of a small point-defense interceptor designed by the engineers A.Ya Bereznyak and A.A. Isayev.
The prototype BI-1 was flown, in glider configuration, on September 10, 1941.
The rocket engine exploded during ground test on February 20, 1942, due to the fragility of the combustion chamber and the first powered flight was conducted by the second prototype BI-2 on May 15, 1942. During this first flight the engine only worked for just under a minute.
The BI airframe was not properly designed to high-speed flight. On March 27, 1943, the BI-3 prototype suffered compressibility buffeting and was destroyed because of an uncontrollable nose-down pitch at 497 mph (800 km/h).
All the work on the 50 pre-production machines was abandoned but some flight testing was continued with the BI-6 and BI-7 prototypes until 1945.
Bereznyak-Isayev BI technical data
Wingspan: 21.2 ft. (6.48 m), length: 21 ft. (6.4 m), height: 6.8 ft. (2.06 m), wing surface: 75.35 sq. ft. (7 sq. m), take-off weight: 3,710 lb (1,683 kg), estimated maximum speed: 559 mph (900 km/h).
In the Yak-7R modification, proposed in 1942, the M-105 piston engine was replaced by the pilot cockpit and the nose armament. One D-1A rocket motor was mounted in the rear fuselage and two Merkulov DM-4C ramjets were fitted under the wings, but the GKO did not authorize the project and the airframe conversion was never completed.
Yak-7R technical data
Wingspan: 32.8 ft. (10 m), length: 31.4 ft. (9.58 m), height: 7.4 ft. (2.26 m), wing surface: 190.5 sq. ft. (17.15 sq. m).
The loss of official interest in rocket interceptors also affected development of the Tikhonravov I-302, Florov 4302 and Polikarpov Malyutka projects.
The I-302 was flight-tested as a glider from August 1943, but the project was cancelled in March 1944 before the rocket engine was installed in the prototype. The Dushkin/Shtokolov RD-2-M-3V rocket had a main combustion chamber rated at 1,100 kg thrust and a cruise chamber rated at 450 kg thrust.
Two DM-4C ramjets fitted under the wings of the second prototype I-302 P had been planned.
Tikhonravov I-302 technical data
Wingspan: 37 ft. (11.4 m), length: 26.2 ft. (8 m), height: 7.7 ft. (2.36 m), wing surface: 198 sq. ft. (17.8 sq. m), take-off weight: 19,205 lb (8,700 kg), estimated maximum speed: 559 mph (900 km/h).
In 1943 a design team of the Air Force Research Institute (NIIVS), under the leadership of Ilya Florov, was tasked with developing an aerodynamic research rocket plane for testing high-speed wings and control systems.
In 1946, the first prototype, known as Aircraft 4302, was flight tested in glider configuration.
In August 1947, the second prototype was flown at 323 mph (520 km/h) powered by one RD-2M-3 rocket motor with two combustion chambers rated at 1,450 and 400 kg thrust.
The project was cancelled in favour of the MiG I-270.
Florov 4302-02 technical data
Wingspan: 22.7 ft. (6.93 m), length: 23.3 ft. (7.12 m), height: 7 ft. (2.12 m), take-off weight: 5,243 lb (2,398 kg), estimated maximum speed: 323 mph (520 km/h).
The Malyutka project had not yet reached the prototype stage when it was cancelled on July 30, 1944.
Malyutka technical data
Wingspan: 21 ft. (6.4 m), length: 20.7 ft. (6.3 m), height: 8.8 ft. (2.69 m), wing surface: 108 sq. ft. (10 sq. m), take-off weight: 5,622 lb (2,550 kg), estimated maximum speed: 544 mph (875 km/h).
Sergei Korolev proposed a rocket-boosted version of the Lavochkin La-5 standard under the La-5 VI (Visotnyi Istrebitel) codename.
The modification consisted on three Glushko RD-1 Khz bipropellant rocket motors, with electric ignition system, mounted under the wings and in the rear fuselage.
It was expected a top speed of 590 mph (950 km/h) and 55,760 ft. (17,000 m) ceiling but the Lavochkin design bureau estimated that the rocket fuel could react with wood causing fires and decided to use a La-7, with metallic structure.
The prototype La-7R was flight tested in October 1944, reaching 461 mph (742 km/h) powered by one M-82 reciprocating engine and one acid/kerosene rocket motor RD-1 KhZ with 300 kg peak thrust.
The second prototype attained 494 mph (795 km/h) and 42,640 ft. (13,000 m) ceiling powered by one ZhRD-1 rocket with hypergolic chemical ignition.
On May 12, 1945, the engine exploded during ground test destroying the prototype. Operation with the ZhRD-1 was found to be extremely hazardous, with explosions a common occurrence.
Flight testing continued until February 1945.
Lavochkin La-7R technical data
Wingspan: 32 ft. (9.8 m), length: 28.4 ft. (8.67 m), height: 2.54 ft. (2.7 m), wing surface: 189.3 sq. ft. (17.59 sq. m), take-off weight: 7,704 lb. (3,490 Kg).
A third prototype named La-120 R was flown in January 1945 reaching 500 mph (805 km/h) powered by one RD-1 CH2-X3 rocket.
The Yak-3 RD prototype was flight tested on December 22, 1944, powered by one VK-105 PF2 piston engine and one RD-1 KhZ
The rocket engine proved to be unreliable and was replaced by a ZhRD-1. The Yak-3R attained 486 mph (782 km/h) flying at 25,590 ft. (7,800 m).
Rocket malfunction continued. On May 14, 1945, there was an explosion during the ground tests.
On August 16, 1945, during a 510 mph (820 km/h) run at 8,200 ft (2,500 m) the prototype suddenly entered a steep dive and crashed.
Yakovlev Yak-3 RD technical data
Wingspan: 30 ft. (9.2 m), length: 29.6 ft. (9.02 m), height: 7.9 ft. (2.42 m), wing surface: 159.6 sq. ft. (14.83 sq. m), take-off weight: 7,616 lb. (3,450 Kg).