The short answer

It depends which half you mean. People often say “Starship” for the whole rocket, but technically Starship is just the upper stage. So:

The Super Heavy booster has 33 Raptors, arranged in three rings — 3 in the centre, 10 in the middle, 20 around the outside — producing roughly 74 meganewtons (about 16.7 million pounds) of thrust at liftoff on Raptor 2, the most powerful rocket ever to fly. The Starship upper stage adds 6: three sea-level Raptors and three vacuum-optimised Raptor Vacuum engines. Total in the stack: 39.

One caveat that matters for every number on this page: there are three generations of the engine — Raptor 1, 2 and 3 — and their specs differ sharply, so it's always worth naming the version. See how Raptor evolved ↓

Which engines actually steer

Not all 33 swivel. On the booster, the 13 inner engines (the 3 central and 10 middle ones) gimbal to steer; the outer 20 are fixed and simply provide thrust. On the upper stage, the three sea-level Raptors gimbal — they're what re-light to flip the ship upright for landing — while the three Raptor Vacuum engines are bolted in place. Toggle the highlight in the explorer above to see the split.

The evolution of Raptor: V1 → V2 → V3

There isn't one “Raptor” — there are three generations, and the differences are huge, so it's worth always naming the version. Each one is roughly the same physical size (~3.1 m tall, 1.3 m across), yet across the three SpaceX has raised thrust by about 50% while cutting mass by a quarter and pushing chamber pressure ever higher.

The headline numbers tell the arc: Raptor 1 made 185 tf at ~250 bar and weighed about 2,080 kg. Raptor 2 jumped to 230 tf at 300 bar for 1,630 kg — and that 300 bar alone broke the previous chamber-pressure record held by Russia's RD-180 (267 bar). Raptor 3targets ~280 tf at 350 bar for just 1,525 kg, having already been test-fired to 269 tf. Its thrust-to-weight ratio climbed from about 89 (Raptor 1) to 164 (Raptor 3).

Which one is flying matters: the Super Heavy boosters that flew the integrated test flights used Raptor 2, while Raptor 3 — the version SpaceX intends to mass-produce — is entering service on later vehicles (first on Booster 19 and Ship 39). So a “Starship liftoff thrust” figure of ~74 MN is a Raptor 2 number; a full Raptor 3 booster would be closer to ~90 MN.

Raptor 2 & Raptor 3 — full specifications

Raptor is a generational leap over Merlin. It burns methane instead of kerosene, runs the fiendishly difficult full-flow staged-combustion cycle, and — from Raptor 2's 300 bar to Raptor 3's 350 bar — operates at the highest chamber pressure of any production engine in history. The table below covers the current sea-level flight engines (Raptor 2, transitioning to Raptor 3).

Full-flow staged combustion — the hard way, done right

A simple engine like Merlin uses a gas-generator cycle: it burns a little propellant just to spin the turbopumps, then throws that exhaust overboard. Raptor wastes nothing. In full-flow staged combustion,all the fuel and all the oxidiser are first turned to hot gas in two separate preburners — one fuel-rich, one oxygen-rich — each driving its own turbopump, before everything meets in the main chamber.

The payoff is higher efficiency, cooler-running turbines, and the ability to push chamber pressure to extremes. The catch is that one preburner runs on hot, high-pressure oxygen gas, which aggressively attacks most metals — which is exactly why it had only ever been attempted twice on test stands before, and never flown until Raptor. SpaceX cracked it partly by developing its own superalloy, SX500, to survive that oxygen-rich environment.

How it steers: ±15°, all-electric

Raptor gimbals up to ±15° on both axes — far more than Merlin's 5° (even more than the Space Shuttle's RS-25 at 12.5°). That wide range is what lets Starship perform its dramatic “belly-flop” flip-and-burn landing, swinging the engines hard to rotate the ship upright in the final seconds.

And unlike Merlin's fuel-driven hydraulics, Raptor switched to an all-electric thrust vector control system from Raptor 2 onward: electric motors tilt the engines, which SpaceX says has fewer potential points of failure and is significantly more energy-efficient than hydraulics — and it removes the whole hydraulic power unit from the rocket.

How they're built — and how many

Building a Mars fleet means building Raptors like a car factory builds engines. SpaceX's dedicated Raptor plant near McGregor, Texas is designed to mass-produce 800–1,000 engines a year, at a peak rate of two to four engines per day. In October 2022 a NASA official noted SpaceX had sustained roughly one Raptor per day for a full week — an unheard-of cadence for a large liquid engine.

The ramp tells the story of simplification: the first 100 Raptor 1 engines took about 36 months, but SpaceX then built 200 Raptor 2 engines in roughly a single year— about six times faster — by deleting flanges, removing the main-chamber igniters, and 3D-printing a large share of the parts. Raptor 3 goes further still, integrating the plumbing and cooling into the engine body so it needs no heat shield at all. Like Merlin, every engine is hot-fire tested at McGregor before flight, and each is designed for 50-plus reuses. SpaceX has never disclosed a per-engine head-count.

The patents behind Raptor — there aren't any

As with Merlin, the honest answer to “what patents make Raptor possible” is: none that SpaceX will show you. The company deliberately keeps essentially no patents on its rocket technology, protecting it as trade secrets — Musk's long-standing argument being that publishing patents would hand competitors a complete “recipe book.” The genuine enablers of Raptor aren't legal filings but engineering: the full-flow cycle, the SX500 oxygen-resistant superalloy, extreme additive manufacturing, and an all-electric gimbal.

Raptor is the methane future. Its predecessor, Merlin, is the kerosene engine that has flown more times than any other — simpler, hydraulic-steered, and proven across hundreds of launches.

Sources

• Wikipedia — SpaceX Raptor. Thrust, Isp, chamber pressure, mixture ratio, SX500 alloy and the full-flow cycle.
• Everyday Astronaut — Raptor 1 vs Raptor 2. The 3/10/20 ring layout, 15° gimbal, and the version-by-version thrust, mass and 300-bar / RD-180 chamber-pressure figures.
• NextBigFuture — Raptor 3 test fire. 350 bar and 269 tf demonstrated; ~280 tf target.
• Teslarati — 200th Raptor 2. Production cadence: 200 engines in ~1 year vs 100 in 36 months.

Raptor is evolving fast; figures track the flight-proven Raptor 2 with Raptor 3 targets noted. Engine counts can change between Starship versions, and SpaceX does not publish official gimbal limits.

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