The purpose of the present paper is to study the opportunity of deciding the problem of horizontal start and landings from the surface of ocean on the basis of ekranoplanes already immediate prospects of mass around 750 tons and aerospace airplanes of mass up to 300 tons that could be feasible in a shorter-range project. The executed researches allow to estimate the structure of marine start system with usage of such ekranoplanes and ASP, the necessary characteristics of ekranoplanes and applicable space vehicles, to estimate the basic features of ekranoplanes and ASP interplay.
1. SYSTEM OF MARINE LAUNCH AND LANDING OF REUSABLE SPACE VEHICLES (WIG SEA LAUNCH - WSL)
The system of horizontal marine start and landing WSL of reusable space vehicles is intended for delivery of a payload on low orbits, including polar and equatorial ones.
1.1. Structure of the system.
The infrastructure of the WSL system should actuate two parts - ground-level and purely marine one.
The ground-level part consists of the following components:
- port-base for ships of the system, where the terminal for parking and loading of a delivery-ship for ASP transport, for ekranoplanes and ships of maintenance, and also assembly-test complex are arranged;
- transport system intended for delivery the ASP components, fuel, payload, etc, from the manufacturers in port-base of WSL system;
- ground-based means of trajectory distance measurements, flight control, navigational and hydrometeorological maintenance.
The marine part actuates:
- delivery-ship for ASP transport, equipped with the means of ASP overload on ekranoplane and realization of completing pre-launch procedures;
- ekranoplane as speed-up and receiving mean for ASP;
- other vessels for maintenance of operation of WSL system.
1.2. Operation of the system.
During realization of space vehicles start the delivery-ship for ASP transport the vessels of maintenance and ekranoplane are put forward to the launch area, where the pre-launch procedure for ASP (Fig.2) is completed.
Directly before the start the ASP overload on ekranoplane and charging both of them by fuel are made. Then the take-off of ekranoplane with ASP on board is implemented. At achievement of an indispensable running speed of ekranoplane the engine start-up and ASP separation is executed. In the case of using two-stage ASP, after staging at the altitude of about 30000 m the completed stage lands onto a flying ekranoplane and then is overloaded on a delivery-vessel. The landing of orbital stage on a flying ekranoplane after its returning into atmosphere is similarly committed. This stage is also conveyed on a delivery-vessel where it is docked with the first stage and all complex is prepared for a new start. In all cases the docking of ASP stages and ekranoplane is implemented after equalizing their speeds (at zero relative velocity, i.e. vertical docking) with the help of special docking units with catchers.
Apart from earlier indicated advantages of the set up scheme of marine horizontal start in compare with overland horizontal start, it is possible to relate the following:
- ASP propulsion systems are actuated in activity already at high subsonic speed, which is sufficient for start of straight-flow air-breathing engines, being cruising ones at an atmospheric segment of ASP flight; using of straight-flow air-breathing engines instead of turbojets allows to lower considerably the mass of ASP propulsion system, to simplify its design, to improve the reliability of operating:
- ASP fuel saving in speed range of up to 150 m/s is provided, that allows to increase mass of payload;
- taking into consideration the additional speed obtained at the expense of equatorial start, initial orbital speed of ASP about 600 m/s can be provided;
- take-off and landing on the moving ekranoplane allow to lower considerably the weight of ASP landing gear, that also increases its payload.
The executed estimations demonstrate, that at the expense of use of a speed-up-receiving ekranoplane for start and reception the increase of ASP payload can reach 30-40 %.
Fig. 2 The scheme of WSL system operation.
2. TECHNICAL MEANS OF THE SYSTEM
2.1. Speed-up-receiving ekranoplane.
The first expeariance of heavy ekranoplanes constructing was accumulated in Russia in Alexeev's Central Hydrofoil Design Bureau. In 1964 the largest up to present time ekranoplane "KM" of 500 tons was built, in 1989 the missile launcher ekranoplane "Lun" (about 400 tons) was enlisted in the Navy. The investigations on ekranoplanes using for implementation from them of take-off and landing modes of flying vehicles were carried out in Russia from early 70th. As a result of fulfilment of a large volume of design, theoretical and experimental researches in Krylov's Ship-building Research Institute the technical appearance of ekranoplane with a take-off mass of 750 tons was based [3,6,7]. It can be used, particular, as the speed-up-receiving ekranoplane for reusable space airplanes.
This ekranoplane has the scheme "combined wing" with two bodies - fuselages similarly to vessels of a catamaran type. In the nose part of ekranoplane the engines are arranged which removing gas jets during takeoff of ekranoplane and during ASP take-off - landing are routed by special deflectors under the central wing, thus creating an additional lift for ekranoplane and not affecting on ASP.
ASP places on a central wing. With the purposes of the clearing of ekranoplane aft and for facilitation of ASP withdrawal and approach the tail unit of ekranoplane is splited with a double vertical tail (Fig. 3). The ekranoplane is capable to execute the long motion on water in displacement mode.
The main technical characteristics of ekranoplane are:
・Full take-off mass with ASP on board - 750 tons:
・Main propulsive plant - 6 turbojets with thrust of 30-35 tons each;
・Propulsive plant of a low speed - 2 fast-running diesel engines;
・Flight speed - 550-600 km/h;
・low speed - 25 km/h.
