Terminal control algorithms in designing re-entered space vehicles

V.A.Afanasyev

SRC "KB of Academician V.P.Makeyev's name", Miass, Russia

e-mail: ava46@mail.ru

G.L.Degtyarev, A.S.Meshchanov, T.K.Sirazetdinov

KSTU of A.N.Tupolev's name (KAI), Kazan, Russia

e-mail: mas41@mi.ru

 

The fatal accident with the Columbia space shuttle has confirmed a truth that a descent in the atmosphere is the most complicated and responsible return phase exposed to actions of large aerodynamic g-loads and high-heat flux. Therefore it is difficult to overestimate the significance of simple and reliable control algorithms guaranteeing safe and satisfactory conditions for a RSV descent and securing the high quality of its designing. Development of the control algorithms has been initiated for a RSV with the cone-shaped aerodynamic configuration in which control moment is produced by an engine mounted near its base. The same rocket engine produces trimming angle of attack and controls the attitude. The first control algorithm has been developed by a method of multi-step terminal control (MTC) for a trajectory set containing a horizontal flight leg in atmosphere.

Perestroika in Russia has been marked by an invention of a new RSV. It seems if any two cone-shaped RSVs are connected by its bases each other then a completely new two-cone space vehicle is created joining functions of a long-term satellite with functions of a return vehicle owing to additional functional possibilities of feasible engines and completely new operational properties of the two-cone aerodynamic configuration.

Using the method of MTC we have synthesized a number of control algorithms for RSVs soft landing by means of reactive forces including algorithms on the base of the reverse problem of dynamic and taking in consideration a delay in an onboard computer. The algorithms are simple in application and safety in servicing and provide a high accuracy in terminal coordinates during landing. These properties are particularly significant in space touring. The first results in resolving of the common problem of control and designing have been obtained for cone-shaped RSVs which owing to their specific aerodynamic configuration have the self-trimming with a large angle of attack and consequently a large transversal g-load maintained without a control moment. We have made a set of designing methods by using numerical ways in resolving of the basic control problem.

The idea how to have effective aerodynamic braking in atmosphere by using an own double case transformed in the axial configuration during descent has been realized in a new conception on a space transformation launch vehicle (TLV) for servicing ISS, on which the authors have a patent with the invention priority of 21 February 2001. We have suggested a conception of the space transport system (STS) for servicing ISS that is to make a set of TLVs of different diameters and lengths. Mounting a smaller TLV on a TLV of larger dimensions we can create a two-stage STS the first stage of which also brakes in atmosphere by means of transformation in the axial arrangement. The module principle of construction permits us to make third-stage STS and also to use transport aircraft for its acceleration. At last the transformation principle during atmosphere braking opens a direction in structural modification STS as a transforming air-space craft with horizontal landing. Its braking in atmosphere is achieved by means of resistance of the whole surface of rocket bases forming the fuselage of the air-space craft.