EPOS plane

Work on the SPIRAL project has made it possible to improve knowledge in the fields:

• experimental aerodynamics, development of wind tunnel - TsAGI;
• heat transfer, full size models - institute of scientist-navigation of M.Gromova;
• design and creation of navigation systems - institute of electromechanics and automatic of Moscow;
• development of radionavigation and landing systems - research center of radio-equipment of the Union (ВНИИРА);
• trajectory control system - РПКБ;
• information imagery - special engineering and design department of LIA, M.Gromova;
• altimeters - УПКБ;
• airbreathing engines - ТМКБ Union.

It should be remembered that in the USSR the lobby of cosmonautic (General Ministry of the Mechanical engineering industry - MOM) was the most powerful in the country and competed with the one of aeronautics (Ministry for the Aircraft industry - МАП), and it is surprising to see the quantity of work made for the SPIRAL project (which was not directly attached to the cosmonautic industry).

For the test in real conditions of the aerodynamic data, control in the air, on-board systems, the study of the stability characteristics and the dirigibility with various stages of the flight (including high altitudes, hypersonic and supersonic speed), estimates of heat ranges, and the tests of athermic materials, as well as the tests of the landers, the analogue orbital space-plane was to be launched from the carrier aircraft TU-95. Before shutting down the project the orbital space-plane had been built in 3 specimens. The plane for the subsonic speed of code name "105.11", the plane for supersonic "105.12", and hypersonic speeds "105.13". To test the planes in the space flight, BOR models (Orbital Plane without Pilot) were built.

Numerous studies undertaken in the wind tunnels of TsAGI, on EPOS models, by simulating various stages of the flight, have made it possible to define with a high degree of quality the design features of the orbital space-plane. In parallel to the studies undertaken on the orbital space-plane, BOR models (scales 1:3 and 1:2) were used for the orbital flights by the subsidiary company of Doubneskov at OKB-155 created by S.S.Judanov. P.Vladychin and A.A.Kondratov.

In 1968 collective OKB A.I. Mikoyan, with the collaboration of the specialists of the subsidiary company OKB of Doubneskov carry out the requirements for the development of the analogue orbital space-plane "105.11", which was given to the factory of Doubneskov for the production (Blohin J.D., Reshetnikov D.A., Saenko V.I. etc).

To avoid confusion we will note that according to preparatory project the EPOS term indicated the analogue plane "50.11" with 2 rocket engines and launched by carrier aircraft TU-95 having to reach an altitude of 120 km and a speed of M=6-8.

During the period of 1968-1971 the factory of Doubneskov built:

• parts of the plane (nose of the fuselage, wings, elevons, the vertical stabilizer and the rudder) for the tests.
• a model for the static tests.
• a complete model for the flight, the analogue plane "105.11".

The nose part and the cockpit were used as back-up system in case of damage. After the transfer of these parts to TsAGI, under the direction of Rema Vassilievitch Studneva, was to create the first simulator of the country, the MK-10, with 2 degrees of freedom for manual piloting. It is Gavrilovitch Fastovets which was attached to the development of the control system and which became the first pilot thereafter to take off the EPOS.

The main difficulty during the production of the EPOS was the realization of rigid beam. Each beams was submitted to tens points of constraints in 4 to 7 directions. According to the documentation these beams were to be manufactured in a new steel ВКЛ-3 by moulding on the shell.

Since the analogue plane "105.11" received during later work the name of EPOS (do not confuse with the orbital EPOS - "50"!), we will use EPOS in the rest of the document to speak about this plane.

The analogue plane "105.11" (product number N7510511101) has wings with variable angle (-5° to 95° from the vertical). Because of the specific look of the plane, they gave it the name "lapote" (shoe out of wooden of bad quality). The engine which powers it is a TRD RD-36K of P.A.Kolesova (also used in marine aviation on the attack Yack-38 planes). This engine was located under the vertical stabilizer not to deform the "lifting body" of the plane.

The EPOS was equipped with 4 landing gear (ski instead of wheels). However to ease the takeoff of the analogue plane the "105.11" front landing gear were equipped with wheels (nondirectional), only their independent blocking was possible. This system was manufactured in Gorki by the aircraft factory.

The orientation of the plane was done by blocking one or the other of the wheels in an independent way (these trains could not not roll back because housing was envisaged for "lids slide blocks" and not for the wheels). But the modeling of the system with wheels on the front and skis to the back, showed that for the speeds ranges of use the plane can overturn. The solution to solve this problem is to move the gravity centre backwards (by raising the front landing gears) to increase the pressure on the skis. Another solution consisted in decreasing the surface of the skis to increase the pressure artificially. But this solution made problems, if the skis was too small it will thrust in the ground and were torn off.

Tests of the EPOS

The tests of the analogue plane were carried out on the military base OKB A.I.Mikoyan integrated into the state polygon of research of the Air Army Forces (ГНИИ, air force) at Ahtubinske in Astrakhan. The plane was piloted by the test pilot Aviard Gavrilovitch Fastovets which was already familiar with this one because it had worked on the dashboard MK-10 at TsAGI. Other air specialists came to be attached to the project, the general engineer of SPIRAL was Vadim Orlov, then Vladislav Chernobrivtsev.

The purpose of the tests on the analogue plane were done in 2 stages, the first was:

• The definition of the stability characteristics of flight and the maneuverability of the plane on the landing strip with the skis.
• The definition of the takeoff and landing characteristics.
• The definition of the loads on the landing and the behavior of the frame fasteners.
• The estimate of the work capacity of the engine, the on-board equipment.
• The definition of the characteristics of flight of the plane at low altitude (500 m).

The tests were made increasing constantly the speed then a small flight at the end. The tests were carried out on a track of 5 km length and 500 m width. Surface was plane but the ground was not homogeneous. There was no means of precise measurement, painted cones were laid out every 200 m on both sides of the track. Moreover the landing strip was to 25-30 km from there.

The first flight took place on December 2, 1975. During this flight the plane reached the speed of 254 km/h.

The preparation for the flight was done as follows: the vertical stabilizer of the plane was removed and it was placed in a truck. The convoys made up of many car moved to the takeoff track at low speed. There the vertical stabilizer was assembled, then various tests were led on the on-board systems and the engine, after the validation of this phase the pilot (A.Fastovets) took seat in the cabin, the preparation of a test took practically a day.

The pilots doubted the stability of the plane (because of the ski) on ground, and for this reason it was asked to them to position the elevons to charge to the maximum the skis and thus increasing stability. In addition there were fears which that the skis could get in the ground like plough, but that did not occur. The trace of the skis in the ground remained small depth. As speed increased the direction of the plane was not more carried out by the wheels (braking one or the other) but by the rudder, until reaching the speed of takeoff.

But the more speed increased and the more difficult the plane was to control, isome times it moved from 150 with 180 m of the central line of the track. The insistent recommendations of the leaders to the pilot to maintain the trajectory did not give anything. The various reports on this problem started to arrive to Moscow and caused the nervousness of the chief of the engineering and design department.

On July 20, 1976 took place the first takeoff of the plane. The length of the track did not make it possible to the plane to fly more than a few seconds 10-15 s. Then the plane landed in straight line. During the first flight the plane showed good characteristics and reached 355 km/h and 12 m height. The flight occurred without problem contrary to simulations at TsAGI where there was a problem with the controller of altitude.

The first range tests included 23 operations, like increasing speed (slow and fast, near to takeoff), flight within the limit of the track (1-2 km of distance and 12m of altitude) and the first long flight 11/10/1976 (landing on another track located at 20 km of takeoff, whose flight plan is on the diagram on the left). The tests of fast speed and takeoff were carried out by Igor Volk and Valery Menitsky (the 2 received later the title of Hero of the Soviet Union and test pilot of the USSR), Vassily Urjadov (hero of the USSR and test pilot of the USSR) and Alexandre Fedotov (at that time former chief-pilot of the Mikoyan company).

Caption of the photograph:
Orbital experimental space-plane (EPOS, product number "105.11") - the atmospheric analogue plane of the orbital space-plane according to the program of the aerospace system "SPIRAL" after the flight from one track to another. In top on the right - the autograph of the experimenter-pilot Aviard Fastovets. Photograph of the personal records of S. A.Trufakina.

The analysis of the results of the first stage of the analogue space-plane "105.11" with engine RD-36-35K did not show a weakness on the level of the skis and validated the stability and the dirigibility of the space-plane in the given speed ranges. These tests allowed to validate the takeoff phase (rise in load on the structure during the take-off) and of landing, these data did not exceeded 50% of the forecasts.

First flight

One year later the pilots prepared to the independent flight tests of the EPOS. The plane "105.11" started in the air fixed under the strategic heavy bomber TU-95KM. The choice of this model as a carrier aircraft was not random because the TU-95K ("BK") were already equipped with fixings to carried bombs. Modification of the plane (which one could build 48 cars at the N18 МАП factory) was distinguished from basic model TU-95MA by the attachment unit of the space-plane in the compartment and its of dropping system.

Thereafter the principal part of the TU-95K was equipped with the hold system and the radionavigation system after which it received designation TU-95KM. This plane was appropriate perfectly for the transport of the EPOS, because it had the posibility to use fixings БД-205, the payload being outside under the compartment. As the span of the wings was higher than the width of the compartment, the plane was suspended, half-embedded, under the compartment, the cabin was outside and allowed the pilot to see the flight.

For the 2em stage the wheels of the analogue plane were replaced by the slipping plates final. Put besides these modifications the plane was analogue with that of the tests of the first stage.
The purpose of the tests carried out at the time of the 2em stage were:

• The definition of the trajectory parameters in an atmospheric flight.
• The definition of the flight characteristics, stability, dirigibility in various speeds.
• The estimation of the landing characteristics.
• The estimation of the elements solidity and the frame of the plane.
• The estimation of the engine capacities of operation.

The second stage started in July 1977. First attempts at flights showed the impossibility of the plane to land on a dry track (because of the frictions forces), experimenters found a quaint but a little strange solution to this problem, apply water melons to the landing strip to decrease frictions.

The carrier aircraft did not release inevitably the analogue plane in flight, some times the EPOS's pilotstayed in the cabin of the "105.11", but at the landing of the carrier aircraft he moved in the cabin of the TU-95KM. For the first flight of the carrier aircraft with the analogue plane there was on board only the crew of the first. In the 3 later flights the pilots Aviard Fastovets and Vasily Urjadov were in the compartment of the TU-95KM.

In the following flights the pilots Fastovets, Urjadov, Ostapenko and Fedotov took seats in the cabin of the analogue plane to test the engine, the pneumatic systems, the internal/external connections and the telemetry system. On total 14 flights without detachment were made. In one of the flights the engine had problems, but it was solved by decreasing the thrust gradually. A radio communication is then added between the pilots of the carrier aircraft and the pilot the analogue plane.

After the validation of the joints flights, it was decided to go to the most difficult stage, releasing the EPOS plane for a flight and an autonomous landing. October 27, 1977 the TU-95KM controlled by the usual team, directed by the assistant chief of the bombardment aviation test service, the lieutenant colonel Alexandre Obelovym (thereafter general commander of aviation), the plane rises an altitude of 5500 m, at the vertical of the landing strip of the aerodrome, and flight at 420 km/h. The analogue plane is piloted by Aviard Fastovets.

During the first seconds of the flight, the plane fell at 50-70 m/s. In the event of an engine failure the pilot had to carry out a turn on the left of 90° to land on the track ВПП "Грошев" it is a square of 5 km edge. The operations of flights were carried out with success and the plane landed at the speed of 360 km/h.

Thereafter during the years 1977-78 5 other flights took place. Three of them were achieved by Aviard Fastovets, one by Pierre Ostapenko (hero of the USSR and test pilot of the USSR), and the last by Vassily Urjadov. All these flights were made starting from the TU-95KM at a 5500 m height in speeds 420-460 km/h. All these tests allowed to know the behavior of the plane in subsonic flight:

• The maximum and minimal flight speed is 550-290 km/h.
• The maximum and minimal longitudinal acceleration is ny = 4.0-0.3.
• The maximum slope is of 78°.

The tests flights confirmed the conformity of the calculated datas, the design features of landing and the efficiency of the control commands.

"... characteristics of the plane, such as stability and the dirigibility are satisfactory. The tests have made it possible to check the safety of the plane and the on-board equipment. The limits of overloads of the landing gears do not exceed 70% of the forecasts for the rear landing skis units and 54% for the fronts.".

Four of the flights of the TU-95KM were directed by the chief of the test flotilla the colonel Anatoly Petrovitch Kucherenko. This experiment played a favorable role in his career, because 14 years later it was choosen to fly VMT-T "Atlante" to transport parts of large dimension of the Energia launcher, as well as the Buran shuttle in Baikonur.

On September 13, 1978 during the landing occurred a damage on the analogue plane "105.11". It was piloted by colonel Vasily Urjadov and was accompanied by a MIG-23 piloted by Aviard Fastovets. This landing was done during backlighting and in the fog what did not facilitate the operation. Little time before the flight the track was widened (the flags were moved), but the teams did not have time to prepare the track and there remained rick of ground. In spite of the fact that the test pilot was experimented the flying conditions were so bad that during the landing the plane hit its landing ski against a stone. Plane could be stopped but the shock cracked the frame of the plane.

Lozino-Lozinski went to the company which had manufactured the plane to repair it, which promised the director, but as it had no more fund for the SPIRAL project repair did not take place.

It was the last flight of the EPOS. One can see on the following photographs the analogue plane "105.11" given to the air forces museum (Higher Air academy of Iury Alekseevicha Gagarina) in the suburbs of Moscow.

In accordance with the initial plan НИОКР, a model for subsonic speeds was built, the "105.12" (N7510511201 number). Documentation about this plane was made in 1974 by the working group Dubnenskof of subsidiary company OKB Mikoyan. However the production was reserved for the company Tushino (TMZ, Moscow). In 1976 the model was almost finished, but was not claimed. The "105.12" was equipped with directional wings from 45° to -5°. The 5Я24 rocket, first stage of the C-25 rocket, is used with the plane, is fixed at the back between the fuselage and the heat shield. Released of the analogue plane should have take place at 11 km of altitude and a speed of M=0.8.

At an altitude of 11 km and a speed of M=0.8 the plane is released. Then the pilot make a gliding flight carries out by lowering the wings to 12° to pull up the plane and at 10.3 km height and a speed of M=0.65 start the 5Я24 rocket engine. The engine thrustes the plane up to 15.5 km and gives to him a speed of M=1.69, the slope of the plane is of 26°, then it continues on its parabolic trajectory and reaches the altitude of 16.5 km at M=1. At this point the plane is practically on top of the aerodrome then begins the descent, at 6 km it actuates the turbojet РД36-35К (420 km/h), in the event of breakdown of this one the pilot can turn on the right to land immediately, if not it continues its loop.

For the supersonic model "105.13" (number N7510511301) only the fuselage (of which the heat shield was in the test phase) was manufactured.

End of EPOS project

After the death of A.A.Grechko, Minister of the defense of the USSR, in April 1976, the place was given to D.F.Ustinov. Its opinion on the combat space systems was old, it was in addition on the initiative of the development of the Buran-Energia system, as for SPIRAL, the continuation of the EPOS project was already sealed.

In a letter to the Central Committee of the Communist Party of the Soviet Union, of February 1976, Iury Dmitrievich Blohin tries to convince the ministry to keep opened EPOS project, under pretext that already much of money was versed (75 million roubles), that American also works on a lifting plane (X-24 de McDonnell Douglas) and that by simple modifications it would be possible to increase the plane to increase the number of places and thus to transform it into space shuttle. Other people such as Vladislav Mikhailovitch Chernobrivtsev and the general engineer of ГНИКИ air forces went in this direction. But, alas, the Communist Party did not listen the specialists's point of view.

It was rather easy to close the SPIRAL project because the decision of the government of launching the project was not signed (because of A.A.Grechko), in spite of the support of the armed forces and the ministry of defense. This is why all work was made according to orders of the Ministry of aeronautics.

Moreover, the absence of supports government to this project led the company OKB Mikoyan since 1970-71 to reduce its activities on this project, it was the same for NPO Molniya.

Pictures of the renovation of the EPOS plane in the gallery (year 2008).

Tests pilots of the analogue plane "105.11" (EPOS)

	Guerman Titov (Cosmonaut n°2) (1935 - 2000)
Aviard Fastovets (1937 - 1991)	Alexander Fedotov (1932 – 1984)	Valery Menitsky (1944 - 2008)
Peter Ostapenko (1929 - 2012)	Vassily Urjadov	Igor Volk (1937)