Development planning of the SPIRAL project

Due to a great complexity of the SPIRAL program, the project manager envisaged a gradual progression of work.

1st stage.

The creation of a manned similar plane (number of product "50-11") of 11.85 t including 7.45 t of fuel, driven by 2 rocket engines, and launched from a TU-95 (for the atmospheric flight). The similar plane is not as heavy as the original model and does not have the same dimensions. The goal of this plane is the validation, of the aerodynamic tests, the propulsion system, of some various fuels N2O4 + UDMH, the estimate of the temperatures under conditions close to the space flight (maximum altitude 120 km and speed of M=6-8) and the re-entry in the atmosphere. The similar plane was also capable to land by its own on a traditional aerodrome. It was envisaged to built and test 3 similar planes. The subsonic flight tests were to occur in 1967, the supersonic flights in 1968. The cost of works was 18 million rubles. This stage was like the American project X-15, but the plane was not made out of metal.

2nd stage

The creation of the Experimental Piloted Orbital Aircraft (EPOS, number of product "50"), prototype of the alternative combat space-plane of a weight of 6.8 t for the validation of work on the frame and the main on-board systems. The putting into orbit is made thanks to a rocket 11A511 Soyuz at an altitude 150-160 km and a slope of 51°, the apparatus was to make 2 or 3 revolutions and an operation propelled (combustible N2O4 + UDMH) for a change of orbit of 8°, then to return in the atmosphere and land like a plane. The similarity to the orbital plane was characteristic (identical on-board systems and heat shield). It was envisaged to built and launch 4 planes without pilot in 1969 and manned in 1970. The cost of work was estimated at 65 million rubles.

3rd stage

The creation of a special hypersonic plane (GSR). To accelerate work it was envisaged to initially test this model with engines running on kerosene (tests of 4 flights in M=4 in 1970, cost 140 million rubles). After the validation of the aerodynamics and tests of the GSR at the supersonic speed it was envisaged to pass to hydrogenic fuel by testing 4 planes. The tests of the GSR with hydrogenic fuel were to be carried out in 1972 at a cost of 230 million rubles.

4th stage

Tests of GSR and OS (orbital space-plane) systems equipped with the auxiliary rocket (GSR engines with kerosene) entirely manned in 1972, because the tests on the orbital unmanned space-plane are limited. After the thorough validation and control of all the systems, the manned tests of OS as well as the use of engine with hydrogen was envisaged in 1973. Later tests were to be related to the use of liquid fluorine for oxidant for the auxiliary rocket and OS, and the creation of second stage of the auxiliary rocket with an open cycle engine ГПВРД.

More details on some stages.

The suborbital manned analogue-plane "50-11" 1st stage.

A analogue plane of exact shape to the orbital space-plane was to be built to test the operations of landings, the on-board systems, aerodynamics, the control of the plane as well as the pilot training. Such a plane was launched by the TU-95KM and was powered by engines which can fly in M=6-8 and at an altitude of 50-120 km. As the speed of this plane in the superiors layers of the atmosphere was much less low than the normal model it was envisaged to build it with ordinary materials (aluminium and titanium, steel alloys). According to the project the plane was equipped with 2 engines cluster ЖРД (GRD) worked out by OKB-117 with a thrust of 11.75 t each one (fuel consumption: 81.8 kg/s, specific impulse 319s) and one ТРД (TRD)"36-35" of OKB-36 of traction 2.5 t. The GRD settled with an angle of 11°40" so that the force vectors goes through the gravity centre of the plane.

The use of machines and controlled techniques of production were to make it possible to reduce the costs and production times of the experimental plane. It was considered thereafter, for the analogue plane elaborate at OKB-2 MAP, to modify the engines to reach a speed of M=12-13.

The flight plan proceeded as follows:

After takeoff the carrier aircraft TU-95 rose during one hour at a 11-12 km height and a speed of 830 km/h, then it released the plane. The angle of inclination of the wings at the beginning of the flight is of ψ=20°... 35° (so 70°.. 55° of the horizontal plane). Having ignited the GRD engines (working with 7.5 t of fuel), the analogue plane arrives into 81 s at a speed of 8000 km/h. The engine shutdown appends at 48-50 km. At this time the 2 GRD have burned 6625 kg of fuel. During the later flight (the plane goes on on its trajectory) the plane reaches the altitude of 120 km and a speed of 6800 km/h (M=7.5). In this phase the plane can achieve operations thanks to its GRD engines of a thrust of 1.5t. The entry in the atmosphere is done at a speed of 7250 km/h, the maximum deceleration during the phase of re-entry is of 5.3g. The heat shield heats until 890°C. After going down the atmosphere the wings are spread with an angle ψ = 60° and between 5 and 10 km of altitude the plane uses its TRD engine, to carry out its flight operations, with a thrust of 2.5t due to 300 kg of fuel can fly on 90 km at a speed of 400 km/h. Then, the plane lands, sliding, at a speed of 250 km/h, its mass is 4.4t and the length of the landing race is of 1000-1100m.

The analogue suborbital plane "50-11" was not produced, but its blueprints were used for the design of the analogue "105.11".

First flights of the EPOS in space (number "50"), 2nd stage

The positioning of the EPOS on the 11A511 rocket was studied by the office OKB-1 and its subsidiary company of Kouibychev. The rocket was dimensioned to send 6.8 t of the plane at an altitude of 150 km. Moreover, to reduce aerodynamic turbulences the plane was placed in a conical nose cone. The first flights of the plane were to make it possible to test the engines for changing the orbit. This procedure (to pass from an orbit to the other) was to become the main asset of the orbital space-planes to ensure several rounds above the target. The quantity of fuel was 2t because the load of the 11A511 rocket was limited.

The first orbital test flight was to be like that:

After checking the on-board systems of the EPOS in the assembly building N2 of Baikonur, the tanks was filled up with fuel then the plane is fastens on the Soyuz rocket (11A511). The plane is placed in a cone and its wings are folded up on the back, the rocket made 37 m of height of which 10 m for the plane. The whole is moved on the launching pad where it undergoes the final tests (complex controls, rocket fueling, entrance of the pilot on the space-plane, etc). The launch occurs early in the morning (Moscow time 6h00-9h00) with let them 2 or 3 window for departure according to the weather on the landing aerodromes dispersed all over the USSR. During the rocket fire the pressure is 3600 kg/m2 what subjects the pilot to 4.4g. The rocket puts into orbit the 7t EPOS at an altitude of 130 km, a slope of 51° and a period of revolution of 1h30. Then the space-plane separates from the connections systems of 200 kg and begins controls of the on-board systems during half an hour, whereas on the ground, TsOUP analyzes telemetric information. After which begin the preparation of the operation for the change of orbit, the orientation engines are controlled (ГДУ). During the 2nd revolution, in the tracking area, engines GRD are started during 7 min, being reduced of almost 2t the plane is on a new orbit of 58°45' of slope. The on-board systems are again tested according to the program "development of peace in Space", then begins the preparation of the landing. The wings are put in position (V=60°), the EPOS is directed behind thanks to its engines, and to the top of the Indian Ocean (at 14 000 km of the aerodrome) the breaking impulse is given to penetrate in the atmosphere. The pilot then directs the apparatus with the good angle of attack (M=25). The management of the rise in heat of the apparatus is regulated by modifying the inclination angle (between 0° and 60°) of the plane on the descent trajectory. The change of slope simplifies a lot the management of fuel on the way of descent. The maximum accelerations felt by the pilot do not exceed 1.4g according to axis X (direction chest-back) and 1.4g according to the axis Y (head-foot). After the reduction speed until M=10, the wings are spread with 45°, the final deployment until V=30° occurs at a speed of M=2.5.

At a distance of 60 km from the aerodrome the TRD engine is ignited, developing a thrust of 1000 kgf at M=0.35 and an altitude of 2 000m. That enables him to carry out the operations of deceleration (with a maximum acceleration of 1.5g in the turns) to 400 km/h by lowering the vertical speed to 18 m/s for a slope of 12°. At 500 m of the runway the plane have its landing speed. The plane is inclined with 14° what decreases its aerodynamic qualities and land at the speed of 225-250 km/h, it finishes its sliding at 1000-1700 m, it still should be waited until it cools because he leaves the plasma zone. The ground teams arrive with their chemical protection combination, develop the means of cooling of the apparatus and help the pilot-cosmonaut to left the cockpit.

But that did not occur. Such a flight could have taken place in the 70's, well before the American Shuttle! Indeed, much later after closure of the SPIRAL project, one of the engineers of the program declared: "With the GSR there were still interrogations, but with the EPOS there were no more doubts, we could really build it and it would fly now".

There is very few informations on the other stages of the project.