Falcon 9, taken apart.
X was taken, so we studied it. This is the world's most-flown orbital rocket, the one we're racing, drawn to scale from public numbers. Scroll to take it apart one assembly at a time.
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01 · The stack
Falcon 9 Block 5
A two-stage rocket built to fly again. The first stage lands itself and flies the next mission; the second stage and the payload go on to orbit.
- Height
- 69.8 m
- Diameter
- 3.7 m
- Mass at liftoff
- 549 t
- Flights
- 672
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02 · Payload fairing
The nose: two halves that fly home
A 13.2 m composite shell protects the payload through the atmosphere, then splits in two. Each half glides back under a parachute to be caught and reflown.
- Height
- 13.2 m
- Width
- 5.2 m
- Mass
- 1.7 t
- To low orbit
- 22.8 t
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03 · Second stage
One engine, built for vacuum
The second stage carries 107.5 t of propellant and a single Merlin Vacuum. Its niobium nozzle opens out 165:1 to a 3.3 m mouth, too big to work in air, so it waits inside the interstage until the stages part.
- Thrust
- 934 kN
- Efficiency (Isp)
- 348 s
- Burn
- 397 s
- LOX · RP-1
- 75.2 · 32.3 t
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04 · Interstage and grid fins
Four fins that steer it home
A 4.5 m carbon-fibre sleeve over aluminium honeycomb joins the stages. On the way down, four titanium grid fins fold out to steer the booster to its landing spot. Each is a single casting that needs no heat shield.
- Interstage
- 4.5 m
- Grid fins
- 4 × titanium
- Fin size
- 1.2 × 1.5 m
- Cold-gas pods
- 2
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05 · Liquid oxygen tank
287.4 t of oxygen at 66.5 K
The upper tank holds the oxidiser, chilled to 66.5 K (-206.7 °C), colder than it needs to be to stay liquid, so more fits in. The three lit capsules inside are carbon-wrapped helium bottles: they keep the tank pressed as it drains.
- LOX
- 287.4 t
- Temperature
- 66.5 K
- Helium bottles
- 3 (lit)
- Tank length
- ~22 m*
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06 · Kerosene tank
123.5 t of RP-1
The lower tank holds refined kerosene, chilled to 266.5 K (-6.6 °C) to pack it denser. The oxygen reaches the engines through a transfer tube that runs straight down the middle of it.
- RP-1
- 123.5 t
- Temperature
- 266.5 K
- Mixture
- 2.33 : 1
- Tank length
- ~14 m*
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07 · Merlin 1D engines
Nine engines on the Octaweb
Eight Merlins ring a ninth. Each burns kerosene and oxygen fed by its own turbopump, spun by a small gas generator whose exhaust runs out beside the bell.
- Each, sea level
- 845.2 kN
- All nine
- 7,607 kN
- Isp sea level · vac
- 282 · 311 s
- Burn
- 162 s
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08 · Landing legs
It lands on four legs
Folded against the booster on the way up, four legs swing out just before touchdown and spread 18.3 m wide, about five times the rocket's own width. Boosters have landed 650 times in 658 attempts.
- Legs
- 4
- Span
- 18.3 m
- Landings
- 650 / 658
- Designed for
- 10+ flights
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09 · Liftoff thrust
7,607 kN at full power
Nine engines push with 776 tonnes-force on a 549 t rocket: 1.41 times its own weight, so it climbs from the first second.
- Thrust : weight
- 1.41
- To low orbit
- 18.5–22.8 t
- To Mars
- 4.02 t
- Stage 1 burn
- 162 s
* Tank lengths are worked out from each propellant's mass and density. Sources: SpaceX and Wikipedia (Falcon 9 Block 5, Merlin), checked October 2026.