METHOD FOR PLACING PAYLOAD IN ORBIT BY MULTIFUNCTIONAL...

Aeronautics and astronautics – Spacecraft – With fuel system details

Reexamination Certificate

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Details

C244S158700

Reexamination Certificate

active

06712319

ABSTRACT:

FIELD OF THE INVENTION
The invention relates to the field of rocket-space engineering and may find application during the development of rocket-space systems serving to place manned and unmanned spacecraft, and also other objects of different purpose, on a near-earth orbit.
BACKGROUND OF THE INVENTION
The modern development of space engineering requires the creation of launch vehicles which are capable of delivering spacecraft of different purpose and mass to near-earth orbits at a height of 180-34000 km. Where there is such a variety of tasks, the demand arises for the presence of multifunctional launch vehicles which are capable in the basic or other arrangement of performing these tasks. Launch vehicles of a combined scheme with a multiunit lower stage satisfy this requirement in the best manner. Appropriately selecting the rocket units of the lower stage, it is possible over wide ranges to change the characteristics of the launch vehicle as a whole, achieving their greatest correspondence to the launch program. The advantages of launch vehicles of the combined scheme are manifested to the greatest degree when one of the rocket units of the lower multiunit stage, mainly the central, works for a longer period than the other units. Launch vehicles of the combined scheme make it possible to also optimize the ascent of spacecraft into a near-earth orbit.
A typical example of the use of a multiunit lower stage for placing a payload into a near-earth orbit is the “Ariane” project, in particular, “Ariane-5” (see, for example, Aviation Week and Space Technology, No. 13, 1999, pp. 61, 64-65). The launch vehicle “Ariane-5” has a lower multiunit assembly of rocket units, including a central rocket unit with a cruise LRES and two side rocket units with cruise solid propellant rocket engines (SPREs). The project provides for the use of two variants of a central rocket unit and several variants of side rocket units with different operating times and thrust level of the cruise engines. An acceleration rocket unit and the head unit with the payload are connected to the central rocket unit in accordance with a tandem scheme. At lift-off both SPREs and the LRES of the central rocket unit are fired. When operation of the SPREs ceases, the side rocket units are jettisoned and the launch vehicle continues acceleration with the aid of the cruise LRES of the central rocket unit. When the launch vehicle “Ariane-5” with an enlarged central rocket unit is used, it possible to place a payload with a mass of from 8 tons to 12 tons into a near-earth orbit from the KURU cosmodrome. In order to ascend a smaller payload, for example, with a mass of 6 tons, another central unit with another cruise LRES is necessary. Thus, when a typical construction of a launch vehicle of a combined scheme is used, it is possible, without changing the central rocket unit, to change the mass of the payload being placed into orbit by 1.5 times, which is a typical range of change of the mass of the payload for a modern launch vehicle of the combined scheme. During the refinement of this launch vehicle, separate refinement of the central rocket unit and the side rocket units in all their variants is necessary, and also the testing of different assemblies of the launch vehicle. Since different variants of the rocket units are used in the assembly of the launch vehicle, the refinement of the launch vehicle as a whole takes a large amount of time and requires large expenditures. Furthermore, operation of the launch vehicle is possible only after refinement of at least one assembly of the central and two side rocket units. A substantial drawback of all launch vehicles of a combined scheme, which use side rocket units with SPREs, is the increased ecological contamination of the atmosphere with compounds of chlorine, which are contained in large amounts in the products of combustion of the solid propellant. The increase in the energetic characteristics of the solid propellant results in additional contamination of the atmosphere with toxic products of the combustion of the solid propellant.
Other variants of use of a combined launch vehicle for the ascent of a payload into a near-earth orbit are also proposed.
A method for placing a payload into orbit by a multifunctional launch vehicle of a combined scheme is known and disclosed in U.S. Pat. No. 4,964,340, class 102/377, B 64 G 1/40, Oct. 23, 1990. In accordance with this patent an acceleration rocket unit and a head unit with a payload are mounted on a central rocket unit with a SPRE. A lower multiunit assembly of rocket units is formed by connection of from two to six side rocket units with SPREs to the central rocket unit in accordance with a launch program. During lift-off of a launch vehicle with six side rocket units, SPREs of four lift-off side rocket units are fired and acceleration of the launch vehicle begins. Prior to cutting off the aforesaid rocket units, SPREs of the two remaining side rocket units are fired, after which the four spent rocket units are jettisoned and acceleration of the launch vehicle is continued with use of two SPREs. Before they are cut off, the SPRE of the central rocket unit is fired and the two spent side rocket units are jettisoned. The rocket engines of the acceleration unit are fired after operation of the SPRE of the central rocket unit has ended. The aforesaid method is realized in a launch vehicle of a combined scheme, containing a lower multiunit assembly of rocket units with cruise SPREs, including a central and connected thereto side rocket units and tandem secured on the central unit transition compartment, acceleration rocket units and a head unit with the payload, head domes of the side rocket units and a system for securing the side rocket units to the central unit. Two side rocket units are connected to the central rocket unit in a pitch plane, forming a minimum assembly of a combined launch vehicle with three rocket units in the lower multiunit assembly. Two other variants of the launch vehicle, which realize this method, are formed by additionally connecting to the central rocket unit of the launch vehicle a minimum assembly of either two side rocket units, positioned in the pitch plane, or four side rocket units, positioned symmetrically relative to the pitch plane. The known technical solution makes it possible to use a single-type SPRE for all the rocket units in the lower multiunit assembly, which significantly reduces the expenditures on placing the payload into orbit. However, in this solution the energetic possibilities of the lower multiunit assembly of rocket units is not used to the full extent, since during the first stage of operation of the launch vehicle a portion of the rocket units—three out of seven (more than 40%) for the variant with six side rocket units, does not participate in the process of creating thrust and is a passive mass during the first stage of placing the payload into orbit, which impairs the engine weight efficiency of the launch vehicle and results in a reduction of the mass of the payload to be placed in the near-earth orbit. During the realization of this method for placing a payload into a near-earth orbit, higher loads will act on the launch vehicle as a whole and accordingly on the payload when the SPREs of the side rocket units fire, they beginning to operate, for example, prior to termination of operation of the SPREs of lift-off rocket units, since at the moment of firing the additional SPREs a thrust acts on the launch vehicle both from lift-off SPREs and the thrust of the SPREs of two more side rocket units. In spite of the fact that a single-type SPRE is used in the rocket units, in this construction of the launch vehicle it is not possible to use a standardized rocket unit, since in the case of different assemblies of the launch vehicle a central rocket unit is required with different positioning of the units for securing the side rocket units. During the refinement of this launch vehicle, in addition to refinement of the firing of rocket units with SPREs under on-ground conditions,

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