The Human-Rated Launch Vehicle Mark-3, or HLVM-3, is an advanced, human-rated iteration of the Indian Space Research Organisation's standard heavy-lift LVM-3 rocket.

It has been meticulously engineered to safely transport the Gaganyaan Orbital Module into a 400-kilometre Low Earth Orbit.

While it preserves the fundamental three-stage architecture of the conventional LVM-3, the HLVM-3 stands noticeably taller. This height increase is primarily due to the inclusion of a dedicated Crew Escape System tower on top, alongside significantly upgraded safety margins and fully redundant onboard systems.

The overall vehicle specifications outline a total height of approximately 53 metres, making it taller than the standard 43.5-metre LVM-3. Its lift-off mass reaches approximately 640 tons, while maintaining a core diameter of 4.0 metres.

The rocket is capable of lifting a payload capacity of up to 10,000 kg into a target circular Low Earth Orbit of approximately 400 kilometres, powered by three distinct stages comprising solid boosters, a liquid core, and a cryogenic upper stage.

A detailed stage-by-stage breakdown reveals the intricate engineering behind the launch vehicle. The strap-on boosters consist of two large solid rocket motors, designated as S200, which contain approximately 204 to 205 tons of HTPB solid fuel each with a 3.2-metre diameter to provide the primary lift-off thrust.

The core stage, designated as L110, utilises twin Vikas liquid engines fuelled by approximately 115 tons of liquid propellant consisting of UH25 and dinitrogen tetroxide. Featuring a 4.0-metre diameter, this core stage ignites mid-flight at an altitude of approximately 41.5 kilometres.

The upper stage, designated as C25, is powered by a single indigenous CE-20 cryogenic engine. It has a 4.0-metre diameter and a height of 13.5 metres, containing approximately 28 tons of liquid oxygen and liquid hydrogen while generating roughly 200 kN of nominal thrust.

Finally, the safety system consists of the Crew Escape System, which employs quick-acting, high-burn-rate solid motors using solid propellant. Its sole purpose is to rapidly pull the crew module away to safety in the event of a launch pad or ascent abort.

To satisfy the stringent safety standards required for human spaceflight, ISRO's Gaganyaan modifications introduce several critical upgrades to the baseline LVM-3. The Crew Escape System is mounted at the very top of the rocket, using high-thrust solid motors to rapidly separate and carry the crew capsule away from the booster if any emergency arises on the launch pad or during atmospheric ascent.

Enhanced redundancy has been integrated into critical avionics, navigation, guidance, and control systems, featuring quadruple or dual redundancy to ensure that a single component failure cannot jeopardise the mission.

Furthermore, structural and engine margins have been reinforced, meaning propellant tanks, structural joints, and engines—including the human-rated CE-20 cryogenic engine—are rigorously tested to operate with higher safety margins and reduced vibration levels to ensure astronaut comfort.

An Integrated Vehicle Health Management system is also incorporated, featuring real-time onboard diagnostic sensors that continuously monitor rocket performance and can automatically trigger the Crew Escape System if dangerous anomalies are detected.

IDN (With Agency Inputs)