India’s Ministry of Defence (MoD) announced a major technological achievement: the Defence Research & Development Laboratory (DRDL), a key arm of the Defence Research and Development Organisation (DRDO) based in Hyderabad, had successfully ground-tested a subscale scramjet engine for over 1,000 seconds. This feat marks a decisive step toward India’s ambition of mastering hypersonic propulsion and positions the country alongside global leaders in the field.
On April 26, 2025, India’s Ministry of Defence (MoD) announced a major technological achievement: the Defence Research & Development Laboratory (DRDL), a key arm of the Defence Research and Development Organisation (DRDO) based in Hyderabad, had successfully ground-tested a subscale scramjet engine for over 1,000 seground test builds on the earlier success reported in January 2025, when DRDL achieved 120 seconds of scramjet operation. With the system now proven for much longer durations, India moves closer to testing a full-scale, flight-worthy scramjet combustor. As the Press Information Bureau (PIB) release puts it, “the system will soon be ready for full-scale flight-worthy combustor testing.”
Understanding the importance of this achievement requires a look at the broader strategic landscape. Today, only Russia has operationally deployed an air-breathing hypersonic cruise missile. The United States, China, and several European powers are in pursuit, but none have crossed the operational threshold. India now stands poised to bridge this gap.
DRDL’s present success is rooted in a decade of investment in hypersonic research, most notably through the Hypersonic Technology Demonstrator Vehicle (HSTDV) program. The HSTDV was designed to validate a scramjet engine powered by kerosene, with the goal of achieving autonomous, sustained hypersonic flight.
The HSTDV architecture involved a hypersonic cruise vehicle (CV) mounted atop a launch vehicle (LV). Once boosted to 30-35 km altitude and Mach 6.5 velocity, the cruise vehicle separated, shed its aerodynamic fairings, and engaged its scramjet engine. In its landmark flight on September 7, 2020, the HSTDV demonstrated sustained scramjet-powered flight for over 20 seconds, exceeding its initial targets and establishing India’s technical prowess.
However, achieving longer-duration hypersonic flight meant addressing major engineering challenges, primarily extreme aerodynamic heating, efficient combustion under supersonic airflows, and the structural integrity of vehicle components exposed to temperatures exceeding 2,000°C.
Sustaining hypersonic speeds beyond 20 seconds demanded revolutionary advances in thermal management. DRDL tackled these through two key innovations: active cooling and advanced thermal barrier coatings (TBCs).
Active cooling involves circulating a coolant—typically the same fuel intended for combustion—through channels embedded within the combustor walls. This system absorbs the extreme heat from the hypersonic airflow and combustion gases, preventing structural failure.
The DRDL, alongside Indian industry partners, developed a new endothermic kerosene-based fuel specifically engineered for this purpose. As it flows through the cooling channels, the fuel undergoes controlled chemical reactions that absorb large quantities of heat before it is injected into the combustor. This dual role not only protects the engine structure but enhances combustion efficiency, creating a regenerative thermal cycle critical for sustained hypersonic flight.
Complementing active cooling, DRDL also developed a next-generation ceramic thermal barrier coating. Created in collaboration with a Department of Science & Technology (DST) lab, this TBC can withstand the 2,500°C environment inside the scramjet combustor.
Applied using specialized deposition techniques, the TBC shields metallic components from direct thermal exposure and oxidative damage, significantly extending engine life. Without such protection, prolonged hypersonic flight would lead to catastrophic structural failures.
DRDL’s achievement is not a standalone success. It is the result of an emerging hypersonic ecosystem within India that spans advanced materials science, propulsion engineering, computational fluid dynamics, and systems integration.
Manufacturing capabilities have also scaled to meet stringent requirements, such as producing endothermic fuel at industrial levels with consistent quality. This foundation not only supports current projects but opens pathways for future indigenous hypersonic systems.
India’s progress in hypersonic technology carries significant strategic implications. The country has long sought to balance regional power dynamics, especially with China’s advances in hypersonic weapons and the deployment of Russia’s Zircon missile.
DRDL’s success brings India closer to deploying its own scramjet-powered hypersonic cruise missiles, potentially with operational capabilities rivaling or even surpassing current global benchmarks.
India is known to be working with Russia on the BrahMos-II project, a hypersonic successor to the BrahMos supersonic cruise missile. While it remains unclear whether DRDL’s scramjet engine will directly power the BrahMos-II, the possibility of integrating an indigenous scramjet is significant.
Such a move would not only enhance India’s self-reliance in critical technologies but also potentially improve performance, given that India’s new systems are being tailored specifically for extended endurance and higher thermal loads.
Russia brings crucial expertise in hypersonic guidance, control systems, and vertical launch integration—capabilities honed through the Zircon program. Collaboration in these areas can accelerate India’s deployment timeline while ensuring sovereign control over propulsion systems.
Parallel to scramjet development, India is advancing a Long-Range Hypersonic Missile (LR-HM) program. On November 16, 2024, DRDO successfully flight-tested the LR-HM.
However, official releases did not mention the use of a scramjet engine, suggesting the LR-HM might be a boost-glide vehicle. Such systems achieve hypersonic speeds through an initial rocket boost followed by unpowered glide at high altitudes, a different but complementary approach to scramjet-powered sustained flight.
By pursuing both scramjet and boost-glide pathways, India is diversifying its hypersonic capabilities, ensuring strategic flexibility and adaptability across a range of mission profiles.
The road ahead involves several critical milestones. DRDL must transition from subscale ground tests to full-scale flight tests, validate system reliability under operational conditions, and integrate the scramjet engine with launch platforms and guidance systems.
Challenges remain. The control of hypersonic vehicles, especially during sustained flight, is complex due to highly dynamic aerodynamic forces. Communication, navigation, and targeting systems must also operate seamlessly at extreme velocities.
Yet, if India succeeds, it will join an exclusive club capable of deploying air-breathing hypersonic cruise missiles—a leap that would have profound implications for strategic deterrence, power projection, and national security.
April 26, 2025, may well be remembered as the day India crossed a critical threshold in the race for hypersonic supremacy. DRDL’s 1,000-second scramjet test is not just a scientific triumph; it is a strategic signal.
By mastering the complex interplay of high-speed aerodynamics, combustion physics, and materials science, India has laid the groundwork for operational hypersonic weapons that could change the rules of modern warfare. The world is watching—and India’s journey is only just beginning.
