New Delhi, — April 7, 2026 : The Indian Navy has issued a detailed problem statement titled “Rearming by Drone (REARM-D) at Sea” under the 14th edition of the Defence India Startup Challenge (DISC-14), outlining a requirement for a heavy-lift multi-rotor unmanned aerial vehicle (UAV) capable of reloading surface-to-air missiles (SAMs) into vertical launch system (VLS) cells while warships remain deployed at sea.
The requirement reflects operational challenges observed during sustained maritime deployments, where warships face rapid depletion of onboard SAM inventories while countering low-cost drones and incoming missile threats. At present, replenishment of VLS cells is conducted in harbour using jetty-based crane infrastructure, necessitating the withdrawal of combat vessels from operational areas and resulting in reduced mission availability.
Operational Requirement and Concept of Employment
The REARM-D concept is designed to enable ship-to-ship transfer of missile canisters without requiring vessels to return to port. Under the proposed system, a multi-rotor UAV will transport SAM canisters from a logistics or supply ship to a receiving warship under controlled movement conditions at sea.
During the transfer phase, the UAV will carry the missile canister using a gyro-stabilised platform to minimise oscillation caused by wind, ship motion, and relative movement between vessels. Upon reaching the receiving ship, the UAV will establish a hover position above the designated Vertical Launch Unit (VLU) module and align precisely with the target VLS cell.
A winch-based deployment system integrated into the UAV, supported by real-time stabilisation mechanisms, will then lower the canister vertically into the launch cell. The process will be assisted by a portable and removable loading interface temporarily installed on the selected VLU cell to ensure accurate alignment and safe insertion.
Technical Specifications and Performance Parameters
The Indian Navy has defined stringent technical parameters for the proposed UAV system. The platform must demonstrate an operational endurance exceeding two hours and a payload capacity greater than 900 kilograms, placing it significantly above the capability range of most currently available multi-rotor UAVs in India.
To meet endurance and stability requirements in maritime conditions, the UAV will be powered by an internal combustion engine rather than conventional electric propulsion systems. This configuration is intended to support extended flight duration, sustained hover capability, and reliable performance across varying wind directions, sea states, and ship speeds.
The UAV must also maintain precise positional control during hover and payload deployment, ensuring accurate alignment with VLS cells under dynamic conditions at sea.
Missile Compatibility and Limitations
The REARM-D system is intended to support reloading of medium and short-range naval air defence missiles currently deployed on Indian Navy platforms. These include the Barak-8 Medium-Range Surface-to-Air Missile (MRSAM) and Long-Range Surface-to-Air Missile (LRSAM), as well as future systems such as the Vertical Launch Short Range Surface-to-Air Missile (VLSRSAM).
The payload capacity threshold excludes heavier strike weapons from the scope of the system. Notably, the BrahMos supersonic cruise missile, with an approximate weight of 3,000 kilograms, cannot be handled by the proposed UAV-based rearming solution.
Industrial and Technological Challenges
The development of a multi-rotor UAV capable of lifting payloads in excess of 900 kilograms represents a significant technological step for the domestic defence industry. Most multi-rotor UAVs currently developed in India for defence applications have payload capacities below 100 kilograms.
Achieving the required lift capability, endurance, and stability in maritime environments places the REARM-D system in a category comparable to large electric vertical take-off and landing (eVTOL) aircraft under development. In addition to propulsion and lift challenges, the system must integrate advanced stabilisation, precision navigation, and ship-relative positioning technologies.
DISC-14 Framework and Related Naval Challenges
The REARM-D problem statement is listed as Challenge 35 within DISC-14, which includes a total of 82 problem statements issued by the Indian Army, Indian Navy, Indian Air Force, and Indian Coast Guard. The initiative is being conducted under the Innovations for Defence Excellence (iDEX) framework, aimed at promoting indigenous development of advanced defence technologies through startup participation.
In addition to REARM-D, the Indian Navy has included multiple unmanned and autonomous system requirements in DISC-14. These include vertical take-off and landing (VTOL) UAVs for anti-submarine warfare, submersible intelligence, surveillance, and reconnaissance (ISR) unmanned surface vessels, and long-range VTOL multi-role attack drones.
Global Context and Comparable Developments
The Indian Navy’s focus on at-sea rearming aligns with similar efforts underway in other naval forces. The United States Navy has conducted initial trials of at-sea VLS replenishment using the Transferrable Reload At-sea Method (TRAM), which enables missile transfer from replenishment ships using specialised handling systems.
In 2026, General Dynamics presented a destroyer tender concept designed to support simultaneous reloading of up to four destroyers at sea. The French Navy has also initiated testing of procedures and technologies aimed at enabling at-sea reloading of vertical launch systems.
Strategic Significance
The REARM-D initiative represents an early publicly disclosed indication of the Indian Navy’s intent to develop at-sea rearming capability for vertical launch systems. Such a capability would allow sustained deployment of surface combatants by reducing dependence on port infrastructure and enabling continuous replenishment during operations.
If successfully developed, the system is expected to enhance operational endurance and maintain air defence readiness of naval task groups operating in high-threat environments without interruption to mission timelines.
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