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Spiral OS
Part of Spiral 50-50
Spiral 50-50
Spiral 50-50
Credit: © Mark Wade
Russian manned spaceplane, developed 1965-1980s, including subscale flight article tests. Evolved into the MAKS spaceplane. The Spiral was an ambitious air-launched manned space system designed in the 1960's.

AKA: Article 105;Article 50;LKA. Status: Design 1965.

It consisted of three main components: the GSR reusable hypersonic air-breathing launch aircraft; the RB expendable two stage rocket; and the OS orbital spaceplane. It was abandoned in the 1970's in favor of the Buran, but development of the OS as a spaceplane to be carried aloft by less-ambitious subsonic launch aircraft continued, culminating in the MAKS design of the 1980's.

At the beginning of the 1960's Mikoyan GKAT OKB-155 began work on the Spiral combination aerospace system. In 1965 the advanced project was approved, laying out an ambitious work plan leading to operation of a regular earth-orbit-earth reusable transportation system by the mid-1970's. With Gherman Titov as its head, a Spiral cosmonaut training group was formed in July 1965 (Titov, Dobrovolskiy, Filipchenko, Kuklin, Matinchenko). This was modified on 2 September 1965 to Titov, Beregovoi, Filipchenko, Kuklin, Shatalov. Go-ahead to actually proceed with development of the manned orbital vehicle was given on 26 June 1966 and Lozino-Lozinsky was selected as project manager. A new cosmonaut training group was established in December 1967: Titov, Kizim, Kozelskiy, Lyakhov, Malyshev, Petrushenko.

The Spiral system consisted of three main components:

The GSR was powered by four turbo-ramjet engines, and two variants were planned. The conservative first variant would use kerosene fuel and accelerate to Mach 4 and 22 to 24 km altitude before releasing the RB+OS. The longer-term second variant would use liquid hydrogen fuel, which would allow it to reach Mach 6 and 28-30 km altitude before releasing the upper stages. The GSR would return to its launch base after completing its mission.

The layout of the GSR was that of a large arrow-shaped flying wing. Vertical stabilizers were mounted at the wingtips. The engine bay was under the fuselage, with high bypass engine inlets. On the top of the wing was the launch pylon for the OS+RB, with the nose and tail portions of the pylon enclosed by ogival fairings for aerodynamic reasons.

The RB rocket that would take the OS from the back of the GSR to orbit consisted of a two-stage rocket. The conservative early version would use Liquid oxygen/kerosene propellants; the later advanced version would use Liquid oxygen/liquid hydrogen.

The OS orbital spacecraft was a flat-bottomed lifting body, triangular in planform, with a large upturned nose that earned it the nickname 'Lapot' (wooden shoe). It seems to have been a developed version of the Tsybin PKA orbital spaceplane design of the 1960's, which had the same nickname. . The nose design was found to greatly reduce afterbody heating during re-entry and was adopted by NASA in its HL-20 proposal of the 1980's. Again like the PKA, a unique feature of the OS were the variable dihedral wings. These were set at a 60 degree angle above horizontal during launch, orbit, and re-entry, where they served as vertical stabilizers. After becoming subsonic, dual electric actuators moved them to a horizontal position, where they served as wings, substantially increasing the lift of the spaceplane for air-breathing operations. The main body of the spaceplane had a sweepback angle of 78 degrees, and the wings, 55 degrees. The large vertical stabilizer had a sweepback of 60 degrees. Aerodynamic controls consisted of the vertical rudder, elevons in the wings, and air brakes mounted at the top rear of the fuselage.

The OS would be inserted into an initial 130 km altitude orbit by the RB, where only 2 to 3 revolutions could be maintained before orbital decay. Orbital propulsion consisted of a 1,500 kgf primary engine, with two 40 kgf backup engines. Orbital attitude control and translation were provided by two reaction control system (GDU) pods at the rear of the spaceplane flanking the backup engines. There were a total of six 16 kgf engines for coarse adjustment and ten 1 kgf engines for fine maneuvers. Fuel tanks for these system were located in the center of the spaceplane. All engines worked on N2O4/UDMH.

After completing its mission the OS would enter the earth's atmosphere at a high angle of attack. It was capable of large banking maneuvers in hypersonic flight. During re-entry the wings were held vertically in the aerodynamic shadow of the fuselage shock-wave. The load-bearing structure, like that of the US X-20, consisted of a network of struts and longerons. The outer skin was articulated to permit thermal expansion during re-entry. This light metallic heat shield was of jointed construction and attached at points to the load-carrying inner frame.

After losing most of its velocity, the wings would have been moved to the horizontal lifting position, and the OS would fly to a landing at a conventional airfield. For maneuvering the aircraft in the final landing phase and to provide a once-around capability in the event of a missed approach, a turbine engine, burning kerosene, was installed. The air-breathing propulsion consisted of a Koliesov RD-36-35K turbojet of 2,350 kgf with 500 kg of fuel, which amounted to 10 minutes of cruise at full thrust. In the orbital version, it would give the spaceplane a chance to 'go around' or divert to a secondary airfield in the event of bad weather or a missed approach (the US Shuttle was originally to have such engines, but they were dropped for weight reasons). The 176 kg engine was fed from a dorsal intake at the base of the vertical stabilizer. This intake was covered during launch and orbital operations; an actuator opened the housing once the spaceplane reached subsonic speed.

Landing was made on gear consisting of four skids, in a tail-dragging configuration, the long frontal skids deploying in a complex manner from landing gear bays mounted on the sides of the spaceplane above the heat shield.

The cosmonaut-pilot sat in an insulated escape capsule, which could be ejected free of the spaceplane in an emergency. This capsule was of Soyuz 'headlight'-shaped form. This would be catapulted from the OS, and had its own navigation system, braking rockets, and parachute allowing rescue of the pilot in all flight phases, including 'bail-out from orbit'. Normally the pilot had to climb into the spaceplane through a hatch above the seat.

Controls consisted of a conventional control column and rudder pedals, with separate controllers for the jet engine and the rocket engines. An automatic navigation and control system (SNAU) included an inertial navigation system and operated the aerodynamic or reaction controls according to the fight regime. Manual backup was available for the aerodynamic controls.

During the development phase three single-place experimental reusable prototypes of the OS would be built. These would be built in the same configuration as the Spiral OS, but have somewhat smaller dimensions, so that they could be orbited by a Soyuz launch vehicle. During the preliminary design of the OS, Korolev actually suggested that the test OS be towed into orbit by the launch vehicle (this was not as crazy as it sounds - it would eliminate the aerodynamic problems of mounting the asymmetric payload on the nose of the Soyuz; the OS was designed to resist re-entry temperatures anyway, so could be towed in the rocket exhaust; and it had advantages in case of launch vehicle failure). However the final arrangement had the spaceplane in the conventional location atop the launch vehicle.

For testing the OS in the subsonic terminal approach phase, aircraft-analogues were to be built, powered by a turbojet or rocket and air-launched from a Tu-95 bomber. Two were planned, one to be flown subsonic (article 105-11), and the other up to Mach 6 to 8 (article 105-12). The single reusable orbital manned prototype was designated article 105-13.

An important characteristic of the Spiral was its large usable payload, two to three times greater than that of a conventional launch vehicle of the same mass. Cost per kilogram of payload to orbit would be 3 to 3.5 times less. In addition the system, by using air launch, could reach any orbital inclination, maneuver in space, and return, even in adverse weather conditions.

The project plan for Spiral was as follows:

Initial test of the OS aerodynamic design at all flight regimes was carried out in the wind tunnels of TsAGI. After that, to investigate more completely the hypersonic aerodynamic characteristics and heat shield materials of the OS, 1:3 and 1:2 scale models of the OS were to be built. Unlike the full-scale model, these were had fixed wings and were designated BOR (unpiloted orbital rocketplane).

Interest in the project at higher levels of the Soviet hierarchy was difficult to maintain, due to the massive funding requirements, technical difficulties, and multi-year development program which could not promise quick results. After being advised that he was in command of a dead-end project, Spiral cosmonaut training group leader Titov left in July 1970. He was replaced by Filipchenko from January 1971 to November 1972, and then by Khrunov. Just before its dissolution in December 1973, the Spiral cosmonaut team consisted of Illarionov, Khrunov, Kizim, Kozelskiy, Lyakhov, and Malyshev.

Underfunded from the beginning, the project was finally reoriented to a simple test of the analogue systems without using these as the basis for a flight system. This was now designated EPOS (Experimental Piloted Orbital Aircraft) and would be flown by Soviet Air Force test pilots rather than cosmonauts. In February 1976, with the beginning of work on Buran, the project was effectively ended except for the test of the subsonic 105-11 article already built. The 105-11 incorporated the airframe and some of the systems of the planned orbital version

Initial flights of the EPOS used its own jet engine to take off from unpaved airstrips, with wheels attached to the forward skids. On 11 October 1976 the MiG 105-11 EPOS made its first flight, taking off from an old dirt airstrip near Moscow, flying straight ahead to an altitude of 560 m, and landing at the Zhukovskii flight test center 19 km away. One year later, on November 27, the first air-drop launch from a Tu-95K (used previously for Kh-20 air to surface missile tests) was made from an altitude of 5,000 m, with landing on skids on a beaten earth air strip. The eighth and final flight was made in September 1978, ending in a hard landing which resulted in the spaceplane being written off. All flights were made by test pilot A. G. Festovets. The eight flights were considered sufficient to characterize the spaceplane's subsonic aerodynamic characteristics and air-breathing systems.

Work on Spiral assisted in development of the Buran spaceplane. The BOR subscale spaceplanes built for Spiral were used to test heat shield materials developed for Buran. These BOR-4 unmanned orbiters were equipped with braking engines. After a circuit of the earth, the spacecraft would deorbit, perform a gliding re-entry, followed by parachute deployment, splashdown in the ocean, and recovery by Soviet naval forces. Compared to the Spiral MiG 105-11 EPOS configuration, the BOR-4 had a flattened, wider body with a much smaller vertical stabilizer. The cruise-back turbojet of the 105-11 seems to have been eliminated, and the canted stabilizer tips were cut off at the Mach angle, a MiG trademark.

Although officially the Spiral spaceplane was cancelled, evidence remained that instead the project continued. It may be that the decision was taken to use the Spiral OS configuration for a larger manned orbital vehicle for launch from the Zenit booster (see Uragan Space Interceptor).

Crew Size: 1.

Family: Space station orbit, Spaceplane. Country: Russia. Launch Vehicles: Spiral 50-50. Agency: MiG. Bibliography: 197, 301, 376, 474, 81, 83.
Photo Gallery

Spiral 2Spiral 2
The MIG-105 EPOS (Experimental Passenger Orbital Aircraft displayed at the Monino Air Museum outside of Moscow.

Spiral 3 viewSpiral 3 view
Spiral 3 view drawing
Credit: © Mark Wade

Spiral MiG-105-15Spiral MiG-105-15
Spiral MiG-105-15 drawing
Credit: © Mark Wade

Mig-105 back viewMig-105 back view
Mig-105 back view close-up
Credit: Stefan Wotzlaw

Mig-105 back viewMig-105 back view
Credit: Stefan Wotzlaw

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