Fig. 3 Models of a ekranoplane and aerospace airplane.
Fig. 4 Testing of ekranoplane and ASP models in a wind tunnel.
At designing of ASP glider the special attention was given to integration of a wing, fuselage and propulsion systems of both an accelerating airplane and orbital stage, and also positional relationship of the stages. The shape of accelerating airplane provides accommodation of the second stage in underneath half-buried position. Such layout is expedient from the following reasons:
・The capability of a simultaneous operation of propulsion systems of both stages directly from start is provided, that increases essentially the thrust-to-weight ratio of a complex of ASP flight vehicles at an initial flight segment;
・The full drag of ASP complex is considerably reduced at the expense of reduction of a friction surface and decreasing of an induced drag of configuration units, and also the integral heat flows on hypersound velocities of flight decrease;
・The lower position of the second stage allows to simplify considerably the complex of the assemble-docking equipment for ASP pre-launch procedure, as the need in powerful cranes for mounting the second stage eliminates. The docking of ASP stages can be made by means of "covering" of an accelerating stage on an orbital stage with the subsequent rise of the last one in a niche of accelerating stage fuselage. Such operation can be made on a delivery-vessel or even on the speed-up-receiving ekranoplane directly in the sea.
The main characteristics of ASP:
・Full take-off mass - 300 tons;
・Full weight of an orbital stage (second stage) - 100 tons;
・Crew and payload of a second stage - 6 tons;
・Propulsion system of the first stage - 4 straight-flow air-breathing engines;
・Propulsion system of a second stage - 2 straight-flow air-breathing engines and 2 liquid jet engines.
As executed investigations demonstrate, the simplification of ASP complex is possible at the expense of creation the single-stage ASP of around 300 tons mass with liquid jet engines, however relative weight of payload in this case will be a bit lower.
3. OUTCOMES OF HYDRODYNAMIC INVESTIGATIONS
3.1. Hydrodynamic parameters of the speed-up-receiving ekranoplane.
The improvement of aerohydrodynamics of ekranoplane was fulfilled in wind tunnels, in ship-research stations, on catapults and gas-dynamic stands on opened water areas. It allowed to ensure the necessary parameters of hydrodynamic perfection during takeoff and lift-to-drag ratio and motion stability at flight (Fig.5).
Fig.5. Lift-to-drag ratio Kh on take-off and lift-to-drag ratio Ka of speed-up-receiving ekranoplane against a height of sea waves.
In spite of the fact that ASP start will be implemented, as a rule, in conditions of a calm sea, the power-to-weight ratio of ekranoplane is sufficient for take-off from a sea surface at seaway of number 5 or more (when a wave height of 3% ensuring is more than 3-3,5 m).
3.2. Aerodynamics of joint flight of ekranoplane and ASP
In aerodynamics of common flight of speed-up-receiving ekranoplane and ASP the main interest concentrates in influencing an aerospace airplane established on a central wing of ekranoplane on aerodynamic properties of all complex, in changing the ASP characteristics during its separation from ekranoplane (vertical docking and undocking) and sufficiency of ekranoplane engines thrust flight with ASP on board.
The tests of the complex ekranoplane - ASP in the docked configuration in a wind tunnel have shown that installation of ASP on ekranoplane results to unessential, about 5 %, decreasing of ekranoplane lift coefficient in an effective range of attack angles and altitudes of ekranoplane motion above underlying surface. A drag coefficient changes considerably more essential, its decreasing can be til 25-30%. The general lifi-to-drag ratio of all system (Fig.6) is accordingly reduced. Thus the reducing of lift-to-drag ratio at small altitudes of flight above a surface is relatively less.
