Аннотация
The parts separating in flight, in particular worked-off stages with unused liquid propellant residues components in tanks is one of the major problems related to launch vehicles (LV) with liquid-propellant engines launches. This problem results in: a) the necessity of economic entities territories vast areas providing for the cosmodrome on a permanent or temporary basis, these areas being exposed to fire impact in case of the stage falling and explosion that in taiga impact areas results in problems arising when addressing a number of political, social, economic, organizational and technical issues (nowadays 19 millions hectares territory is allocated for impact areas in Russia, in 2015 Russia realized 29 LV launches with 86 worldwide); b) potential risk for the functioning space systems because of the existence of the LV upper stages with unused propellant residues that remains in the insertion orbits and represent bulk explosive space debris (nowadays 1682 spent upper stages with a total weight of 2705 tons are orbiting the Earth, including 821 stages with a mass of 1189 tons are orbiting at an altitude up to 2000 km). The above issues lead to the necessity of carrying out of the high-volume set of studies and design and construction works implemented by the engineers of LV aimed at the stages fire and explosion safety improvement in relevant areas of the environment. This complex of works includes works on propellant expenditure in tanks management algorithm developing, introducing separate propellant filling in tanks for each LV launch, works on propellant residues quantity in stages tanks reduction at the time of engine cutoff, the impact areas quantity and territories reducing, etc. If there is an intensive launch program of advanced LV of "Angara", "Soyuz" families from Vostochny cosmodrome, the fire and explosion safety issues become more relevant in comparison with the similar problems arising on LV launches from Baikonur cosmodrome. This difference results from the fact that the impact areas of Baikonur cosmodrome are mostly situated in desert and steppe regions, while the impact areas of Vostochny cosmodrome are mostly situated in taiga forest regions with the high fire hazard. In addition, there is a requirement-strengthening tendency of international organizations to reduce pollution of near-Earth space environment protected areas based on the results of aerospace activities. The proposed approach presupposes the abandoning a traditional approach to fire and explosion risk addressing. To solve the referred task, the technology of liquid propellant residues in stage tanks and feed lines almost total extraction is proposed on the basis of these residues convective gasification that practically solves the problem of fire and explosion safety, moreover, the obtained energy resources are targeted to improve launch vehicles performance characteristics including: a) the increase of launched payload mass, b) the range of placing orbits widening, c) LV launch cost decreasing by means of amount of after launch work in the impact areas reduction (search, scrapping, storage, remove to stages fragments disposal places, work for soil neutralization, returning the territory to its original state). The suggested technical solution for LV stages fire and explosion safety ensuring is realized by the installation of the active onboard de-orbiting system of the worked-off stages providing extra propellant reserves for getting by heat carriers (up to 15 % from the propellant residues in tanks mass), this system structure elements (up to 5 % from the mass of "dry" stage structure), the additional autonomous control system over the lower stage.