The Advanced Centre for Energetic Materials (ACEM), Nashik, achieved a major milestone on 12 September 2025 with the successful static firing of the Project K5 Stage‑2 rocket motor.

The test represented a critical validation of ACEM’s advanced composite motor technology and its newly established large‑scale casting and test infrastructure.

The Project K5 Stage‑2 motor belongs to a 10‑ton thrust class and features a composite casing constructed using T700 carbon fibre reinforced with Epofine resin. The motor measures 2680 mm in length and 2400 mm in diameter, reflecting an optimised structure designed for high efficiency, reduced mass, and improved thermal endurance.

The propellant grain is composed of HD 1.3 composite propellant, formed in a deep finocyl configuration consisting of nine fins. This configuration delivers a high burn rate and stable combustion characteristics. ACEM employed an innovative collapsible mandrel technique to cast the deep finocyl grain, reinforcing its capability in advanced propellant processing.

Ignition was achieved through a pyrogen‑type initiation system designed for rapid and reliable motor start‑up. The nozzle system adopts a submerged architecture integrated with two electromechanical actuators to achieve ±2° nozzle flexing for thrust‑vector control. Actuator operations commenced at T0+10 seconds, with real‑time monitoring confirming precise control and stability during vectoring manoeuvres.

Over 250 channels of instrumentation captured comprehensive performance data throughout the static test. The live telemetry included pressure‑time and thrust‑time profiles, which closely matched the predictive ballistic models, validating both the design and simulation integrity. These results confirmed the expected performance margins and verified subsystem reliability across propulsion, ignition, nozzle actuation, and structural responses.

The Test Authorisation Review Board (TARB), chaired by TG Kasturirangan, Ex‑General Manager, Strategic Forces Command, supervised the test. It was witnessed by senior officials including MSR Prasad, Ex‑Director General (Missiles & Strategic Systems), BV Pappa Rao, Ex‑Director, Advanced Systems Laboratory, along with the Project Director, K5, and the General Manager, ACEM.

This motor was processed at ACEM’s newly established 50‑tonne capacity cast‑cure facility, equipped with hopper‑based continuous casting technology. The facility’s success in processing and curing the motor grain demonstrates maturity in indigenous large‑motor casting capability and affirms readiness for future 50‑tonne class motors.

The static firing took place at the refurbished static test facility at ACEM, which has been upgraded with advanced data‑acquisition systems and safety monitoring architecture.

This successful test has validated the precision, safety, and reliability of both the propulsion system and the test infrastructure, marking a pivotal step towards realising India’s next generation of strategic rocket motors under Project K5.

Way Forward

Preparations are underway for maiden underwater trials that will validate both cold-launch and hot-launch sequence reliability, simulating real service conditions aboard Arihant-class nuclear submarines. These trials are critical for establishing the K-5’s operational maturity and verifying its compatibility with submarine launch canisters, gas-ejection mechanisms, and command–control architectures that interface with naval fire-control systems. Engineering teams across DRDO and the Strategic Forces Command are coordinating closely to ensure seamless system integration with the submerged launch platforms.

Transitioning from developmental testing to series production will mark a major technological milestone. Production readiness demands stringent quality assurance and quality control protocols, not only for propulsion stages and re-entry modules but also for guidance, communication and stage separation systems.

The missile’s composite materials, sensor modules, and electronics must exhibit consistent reliability under the extreme temperature, pressure, and vibration conditions of submerged launch environments. Production-standard validation is being designed to replicate simulated seawater pressure and dynamic stress conditions to guarantee readiness for long-duration deployments.

A crucial dimension of this phase will be validation of multiple independently targetable re-entry vehicle (MIRV) capabilities. The K-5 is expected to demonstrate the ability to deliver multiple warheads against distinct targets within a dispersed area, providing a robust second-strike deterrence posture.

Successful demonstration of MIRV technology will mark a step-change in India’s strategic reach, enabling variable payload configurations and target adaptability across vast maritime domains. Each re-entry vehicle will undergo trajectory synchronisation and decoupling validation to confirm precise target allocation and atmospheric re-entry stability.

Integration with India’s Arihant-class SSBNs, and subsequent adaptation for future submarine classes, underscores the importance of standardised canister and launch control frameworks. This modular design principle ensures that newer SSBN platforms under Project S-5 and follow-on iterations can adopt the missile system with minimal reconfiguration.

The missile’s fire-control integration must align with encrypted communication networks and secure launch authorisation protocols, maintaining operational confidentiality and system safety under nuclear command architecture.

As the K-5 system advances toward operational readiness, it symbolises a maturation of India’s strategic deterrent. The development reflects steady progress toward a credible, secure, and survivable sea-based nuclear triad.

The evolution of such a capability will necessitate parallel adaptation of India’s strategic doctrine, especially in reinforcing policies around no-first-use and second-strike assurance undersea. The introduction of MIRV systems further demands refinement of command–control frameworks to ensure precision, accountability, and decision-making resilience.

India’s export control policy and naval doctrine will also need to evolve commensurately. While export of strategic systems will remain restricted, the technological mastery in propulsion, guidance, and composite fabrication could strengthen broader indigenous missile and space programmes.

Responsible stewardship, coupled with a clear doctrinal framework, will reinforce international confidence in India’s strategic stability and its commitment to maintaining deterrence without escalation.

AECM (DRDO) News