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In the frame of a project funded by ESA, a consortium led by Avio in cooperation with Snecma, Cira, and DLR is performing the preliminary design of a High-Thrust in-Space Liquid Propulsion Stage for two different types of manned missions beyond Earth orbit. For these missions, one or two 100 ton stages are to be used to propel a manned vehicle. Thr...
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... is 4 m. The length of the engine thrust frame has been set to 1.5 m which is sufficient to accommodate the RCS tanks and other engine equipment. The baseline design utilises an Aluminium-Lithium (2195T8R78) alloy. Aluminium-Lithium has been selected in favour of classical Aluminium due to its superior specific stiffness (E/ ρ ) and specific strength ( σ/ρ ). Due to possible reactions between the tank walls and MON-3, a liner is necessary. This will be analysed in more details during the following phases. Configurations using monocoque, honeycomb, and stringer/frame-stiffened structures have been compared. The position of the MMH and MON tanks has been varied. Common bulkhead architectures only have been considered. In total over 20 configurations have been analysed and sized for the six identified loads cases. These load cases occur during the launch and during the mission themselves. Both mission A and B have been considered. Analyses have shown that in all cases the stringer- and frame-stiffened structures are heavier than the monocoque variants. Using honeycomb for the engine thrust frame and the electronic assembly could help to reduce the structural mass. However, in this case, the Eigen-frequencies are lower than the requirements. The lowest structural mass has been obtained for a tank structure with 4 m in diameter and the MMH tank placed above the MON-3 tank, with pressure of 5 bar and 6.6 bar respectively. A sketch of the geometry can be seen in Figure 4. The main dimensions of the stage are summarised in Table 2. The total mass of the bare structure has been estimated to be about 2.8 ...
Citations
... Hypergolic propellants such as N 2 O 4 /MMH and N 2 O 4 / UDMH are widely used in USLRE (Aestus, RD861К, AVUM, S5.92 and other). They are not cryogenic (so are storable over long periods), they do not require ignition systems, and they have high density, which, as a whole, makes them attractive in some new developments[6]. The main drawback of these propellants is high toxicity. ...
Improved liquid rocket engine cycles were proposed and analyzed via comparison with existing staged combustion and gas-generator cycles. The key features of the proposed cycles are regenerative cooling of thrust chamber by oxygen and subsequent use of this oxygen for driving one or two oxygen pumps. The fuel pump(s) are driven in a conventional manner, for example, using a fuel-rich gas-generator cycle. Comparison with staged combustion cycle based on oxygen-rich pre-burner showed that one of the proposed semi-expander cycles has a specific impulse only on 0.4% lower while providing much lower oxygen temperature, more efficient tank pressurizing system and built-in roll control. This semi-expander cycle can be considered as a more reliable and cost-effective alternative of staged combustion cycle. Another semi-expander cycle can be considered as an improvement of gas-generator cycle. All proposed semi-expander cycles were developed as a derivative of thrust chamber regenerative cooling performed by oxygen. Analysis of existing oxygen/kerosene engines showed that replacing of kerosene regenerative cooling with oxygen allows a significant increase of achievable specific impulse, via optimization of mixture ratio. It is especially the case for upper stage engines. The increasing of propellants average density can be considered as an additional benefit of mixture ratio optimization. It was demonstrated that oxygen regenerative cooling of thrust chamber is a feasible and the most promising option for oxygen/kerosene engines. Combination of oxygen regenerative cooling and semi-expander cycles potentially allows creating the oxygen/kerosene propulsion systems with minimum specific impulse losses. It is important that such propulsion systems can be fully based on inherited and well-proven technical solutions. A hypothetic upper stage engine with thrust 19.6 kN was chosen as a prospective candidate for theoretical analysis of the proposed semi-expander cycles. The newly-developed software RECS was used for the comparative analysis of engine cycles.
