M K Mishra, General Manager, HAL Aerospace Division handed over the first Mk-lll IS1/2L hardware to VSSC for ‘Gaganyaan-Unmanned Mission’ along with quality clearance documents on June 24, 2021. As one of the critical Gaganyaan protocols, the structure has gone through the third-party inspection for the first time besides the customer’s stringent inspection and clearance.
The Aerospace Division is participating in ISRO’s Gaganyaan manned-mission with supply of assembly hardware for GSLV-MKIIl launch vehicle. Contracts have been concluded with various units of ISRO such as VSSC, LPSC and HSFC for supply of structural assembly and propellant tanks for initial two sets of launch vehicle in unmanned mission and one for manned mission.
A separate quality protocol has been evolved with development of process and quality plan duly approved by expert committees constituted by ISRO. The Interstage IS 1/2L is a cylindrical structure with a diameter of 4000mm, located in between N204 propellant tank and IS 1/2M of L110 stage. The structure is made of Aluminium-Copper alloy, comprises of skin sub-assemblies and five types of rings at various heights. The skin sub-assemblies are reinforced circumferentially with different varieties of stringers.
The structure houses 10 numbers of gas bottles and Gr I & II modules that are required for pressurisation of L110 propellant tanks. The Gr l module reduces the pressure from 345 bar to 11 bar and further to 5 bar by Gr-II module.
The structure consists of cowling assembly for protecting the external pressurisation line which will take the helium gas to UH25 propellant tank a water tank.