Raptor 3

Raptor 3 is the third generation of the rocket engine SpaceX built to power Starship, the largest and most powerful rocket ever flown. It is more powerful than the engines before it, yet lighter and far simpler.

Quick facts

• Engine type: full-flow staged combustion, reusable. (Staged combustion means the engine burns a little of its fuel first to spin its pumps, then burns the rest in the main chamber; “full-flow” means all the propellant passes through that first step.)
• Propellants: subcooled liquid methane (chilled even colder than the point where it normally turns to liquid) as the fuel, plus liquid oxygen as the oxidizer (the substance that lets the fuel burn). This combination is nicknamed “methalox.”
• Thrust (sea-level version): about 280 tonne-force at SpaceX’s stated target, roughly 2.7 meganewtons or about 600,000 pounds of push. As the engine has matured, SpaceX has cited nominal operating figures nearer 250 tf. (Thrust is the pushing force the engine produces.)
• Vacuum version thrust: about 275 tonne-force.
• Specific impulse: about 350 seconds. (This measures fuel efficiency, like a car’s miles per gallon, but for a rocket.)
• Engine mass: 1,525 kg (about 1,720 kg counting the vehicle-side hardware that connects to it).
• Chamber pressure: about 330-350 bar, among the highest of any operational rocket engine.
• Thrust-to-weight ratio: about 163, versus about 141 for Raptor 2 and about 89 for Raptor 1.
• Revealed: August 2, 2024; first flew on a Starship test flight in 2026.

What it is and how it works

Raptor 3 burns liquid methane with liquid oxygen using a full-flow staged combustion cycle. Two small burners, called preburners, each spin a turbopump (a pump driven by a spinning turbine that forces propellant into the engine). One preburner runs fuel-rich and the other oxygen-rich, and all of the propellant is turned into hot gas in these preburners before reaching the main combustion chamber. Almost nothing is wasted overboard, which makes the cycle extremely efficient and lets the engine run at very high chamber pressure (the pressure inside the chamber where everything burns). Higher chamber pressure means more thrust from an engine of a given size.

The headline advance in Raptor 3 is integration and simplification. SpaceX moved the plumbing, wiring, and sensors that used to be bolted onto the outside of earlier engines into the engine’s main body, replaced many bolted joints with welds and single-piece parts, and used regenerative cooling, which routes cold propellant through channels in the hottest components to keep them from overheating. Because the engine now cools and protects itself, it no longer needs the external heat shroud and fire-suppression hardware that Raptor 1 and Raptor 2 required. That cuts mass, part count, and cost.

Why it matters

Raptor 3 is central to making Starship economically reusable. It delivers more thrust at lower mass while removing the heat shroud, sensor harnesses, and fire-suppression systems that complicated earlier engines, which reduces part count, manufacturing cost, and assembly time. That savings is magnified because a single Super Heavy booster carries 33 engines, so even small per-engine improvements scale up dramatically. Its chamber pressure is among the highest ever achieved by an operational rocket engine, and its thrust-to-weight ratio of about 163 is exceptional. The cleaner, self-protecting design is also meant to survive launch and reentry with minimal refurbishment, supporting SpaceX’s goal of rapid, aircraft-like engine reuse for missions to orbit, the Moon, and eventually Mars. Methane is part of that plan partly because it could one day be manufactured on Mars and because it burns relatively cleanly, leaving less residue than kerosene.

Where it is used and notable examples

• Super Heavy booster: the Starship first stage clusters 33 Raptor engines at its base for the enormous force needed at liftoff; Raptor 3 is the generation being introduced for this role.
• Starship upper stage: uses 6 Raptor engines, a mix of sea-level versions and vacuum-optimized “Raptor Vacuum” (RVac) variants with large nozzles for efficiency in space.
• Raptor 2: the 230 tf predecessor that still needed an external heat shroud; Raptor 3 is its direct, more powerful, less complex successor.
• Raptor 1: the first generation, 185 tf and 2,080 kg, which flew on early Starship prototypes and shows how far the design has come.
• Flight testing: Raptor 3 was ground-tested extensively before being introduced on Block 3 / V3 Starship flights in 2026.

One honest caveat: the numbers have shifted as the engine matures. The August 2024 reveal cited about 280 tf at sea level as a target, while 2026 updates referenced nominal figures near 250 tf (and about 275 tf in vacuum). Quoted values depend on whether they describe a target, a typical setting, or a peak, so they are best treated as approximate and evolving.