Fig. 10 The scheme of motion control complex
At approach it is necessary to combine control on errors with control on disturbances
The ASP and ekranoplane relative motion control system becomes closed after their approach to small distance when infra-red video short-range navigation system that gives the high precision estimation of matrix elements λASP - λEKR can operate. This allows to improve considerably the accuracy of control errors measurements and to decrease that errors with no substantial control laws structure replace. The ASP lateral deflections from ekranoplane will be again suppressed generally by ASP ailerons and rudder at stable heading and minimal yaw; flaps and rudder of ASP will provide the required motion altitude and pitch angle correction at the fixed altitude of ekranoplane but ekranoplane will be able to check and control the relative shifts in longitudinal plane by means of its speed control.
At the final stage of docking another additional relative control loop of mating element will be switched on. It is the open loop channel for control of local shift of the mating element. Operating simultaneously with control mechanisms mentioned above, it must process only high-frequency components of control signals increasing operating speed of entire system to signit ficantly decrease control errors corresponding to matrix elementsλASP(t) -λEKR(t) - λM(t).
Notice, that the most unfavourable external disturbance for a loop of lateral deflections depression would be a pulse rush of wind in a cross head direction. But even in this case the error will be acceptable due to the following reasons:
- high landing velocity of ASP will make this impulse short and its influence will be decreased:
- high landing velocity of ASP will increase the effectiveness of its aerodynamic control elements essentially;
- a pulse of wind will influence both ASP and ekranoplane that decrease their relative shift.
Objectively, the accuracy of ASP relative motion control at landing velocity of Mach 0.4-0.5 may be higher than one of ordinary plane motion control at landing on runway at half as much velocity.
5. CONCLUSION
The outcomes of described researches and experiments allow to make a general conclusion about technical feasibility of marine start and landing of reusable aerospace airplanes for injection the payload into low-altitude orbits on the basis of present and short-term planned level of shipbuilding and aerospace technologies.
The economic feasibility of creation of space vehicles launch system with the use of speed-up-receiving ekranoplane should be the following step in the estimation of prospects of WSL system with the comprehensive study of its ecological and other advantages and also attendant problems.
REFERANCES
1. Tomita N., Ohkami Y. "A study on the application of Take-off Assist for a SSTO with Rocket Propulsion", IAF-95V.3.06, 1995
2. Tomita, N., Nebylov, A.V., Sokolov, V.V., Tsurumaru, D., Saotome, T., Ohkami. Y. - "Feasibility Study of a Rocket-Powered HTTL-SSTO with Ekranoplane as Takeoff Assist". 7th AIAA International Aerospace Planes and Hypersonic Technologies and Systems Conference. Norfolk, VA, USA, 1996.
3. Aframeev E.A. "Will the WIG Craft Become Transport of the Future?". Proceedings of Int. Conf."Navy and Shipbuilding Nowadays", St.-Petersburg, Russia, 1996.
4. Tomita, N., Ohkami, Y., Nebylov, A.V., Sokolov, V.V. "The Concept of Heave Ekranoplane Use for Aerospace Plane Horizontal Take Off and Landing". WIGs RINA International Conference. London, 1997.
5. Nebylov. A.V. Tomita N. "Control aspects of aerospace plane docking with ekranoplane fbr water landing". 14th IFAC Symposium on Automatic Control in Aerospace. Seoul, Korea, 1998.
6. Aframeev E.A. "Conceptual bases of WIG craft building: ideas, reality and outlooks", NATO RTO Meeting Proceedings 15" Fluid Dynamics Problems of Vehicles Operating Near or in the Air-Sea Interface", Symposium AVT RTO, Amsterdam, Netherlands, 1998.
7. Aframeev E.A. "Heavy-class ekranoplans to make up Global Rescue System at sea", J. Military Parade, '4 (28), Russia, 1998.
8. Tomita N., Nebylov A.V., Sokolov V.V., Ohkami Y. "Performance and Technological Feasibility of Rocket Powered HTHL-SSTO with Take-off Assist (Aerospace Plane/Ekranoplane)", Acta Astronautica, Vol.45, No.10, 1999.
9. Nebylov A. V., Wilson P. Ekranoplanes: Controlled Flight Close to the Sea. Monograph. WIT-Press/Computational Mechanics Publications, Southampton, UK, 2000.
