NEW DELHI, — April 12, 2026 : India’s Defence Research and Development Organisation (DRDO) has initiated fabrication of specialised jigs and fixtures required for integrating the H1 booster with an indigenous scramjet engine under the Extended Trajectory–Long Duration Hypersonic Cruise Missile (ET-LDHCM) program, being developed as part of the classified Project Vishnu.
The booster designated for this phase is code-named “H1.” Officials confirmed that fabrication of the tooling systems is currently underway and represents a necessary step before structural assembly and integrated testing of the hypersonic vehicle can begin.
Integration Tooling and Technical Role
The specialised jigs and fixtures are being developed to support precise mechanical and aerodynamic alignment between the booster and the air-breathing scramjet engine. These systems are designed to ensure alignment accuracy of critical centerlines required for stable hypersonic flight, maintain structural integrity under high mechanical loads and vibration during launch, and enable repeatability in assembly to maintain consistent tolerances across test and production units.
Defence analysts indicate that the initiation of tooling fabrication reflects a transition in the program from component-level validation to full system integration.
ET-LDHCM Program Overview
The ET-LDHCM is a scramjet-powered, long-range hypersonic cruise missile designed for sustained flight at speeds of up to Mach 8, or approximately 11,000 km/h. The system is intended to operate at lower altitudes to reduce radar detectability and is capable of carrying both conventional and nuclear payloads.
The missile is projected to have an operational range between 1,500 and 2,500 kilometers. Its propulsion system relies on a scramjet engine, which uses atmospheric oxygen for combustion and requires initial acceleration by a high-speed booster such as the H1 to reach operational conditions.
Development Milestones
Recent work by DRDO’s Defence Research and Development Laboratory (DRDL) has supported progress toward this integration phase. In January 2026, DRDL conducted a long-duration ground test of a full-scale, actively cooled scramjet combustor at the Scramjet Connect Pipe Test (SCPT) facility, achieving operation for over 12 minutes under simulated hypersonic conditions.
Earlier tests included a subscale actively cooled combustor run exceeding 1,000 seconds in April 2025, along with additional trials lasting over 60 seconds. These efforts build on earlier work from the Hypersonic Technology Demonstrator Vehicle (HSTDV) program and are focused on enabling sustained scramjet-powered cruise.
Supporting technologies developed for the program include endothermic fuels for active cooling and advanced thermal barrier coatings capable of withstanding temperatures of approximately 2,000°C generated during hypersonic flight.
Manufacturing and Program Status
The ET-LDHCM system is being designed and manufactured at the Dr. A.P.J. Abdul Kalam Missile Complex with participation from Indian private defence firms and small and medium enterprises. Construction activities are reported to be ongoing, with preparations underway for future flight testing, although no official timeline has been announced.
The fabrication of H1 booster integration tooling represents a key step toward full missile assembly. Accurate tooling is required to maintain precision in high-speed, high-temperature environments and to support consistent integration standards across developmental stages.
The ET-LDHCM program forms part of India’s broader hypersonic weapons development effort, which includes both air-breathing cruise missile systems and boost-glide technologies aimed at expanding long-range precision strike capabilities.
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