Development of High Performance Liquid Apogee Motor for Geostationary Spacecraft

摘要

The 440N bipropellant Liquid Apogee Motor (LAM) is used for orbit raising of satellites from Geostationary Transfer Orbit to Geostationary Orbit. Liquid Propulsion Systems Centre (LPSC) of Indian Space Research Organisation(ISRO) has developed and qualified LAM and it was successfully used in thirty seven spacecraft missions including Chandrayaan-1, the mission to moon and in Mangalyaan, the mission to Mars. The propellant combination employed is MON-3 & MMH at a mixture ratio of 1.6 ± 0.05. The engine with an area ratio(AR) of 160 delivers a thrust of 440N with a specific impulse(ISP) of 315s(nominal). The performance is comparable in the international scenario for this class of engines having identical AR. ISRO is venturing to launch heavier satellites in near future and LPSC has undertaken a programme to develop an engine with improved performance. Towards this, a modified version of LAM with enhanced AR is designed. AR is enhanced from 160 to 250 to improve the ISP by over 1% which will result in a propellant saving thus extending the satellite life. The injector configuration remains the same as that of the existing LAM and the nozzle is redesigned for enhanced AR to achieve a higher thrust amplification factor. Two engines were realised and subjected to qualification level vibration and thermo vacuum tests. Subsequently, the engines were subjected to qualification hot tests in high altitude facility. Both the engines delivered an ISP of 319s thereby validating the design modification. The engines were also subjected to off- nominal tests and this version engine will be inducted to Geostationary Spacecraft soon. This paper presents the details of the qualification tests carried out.