The mouth
Nothing burns yet; you are only being organized. Four-point-seven metres of nacelle slow the oncoming air and straighten it into an even, gentle stream — a fan cannot sip messy air.
01Thrust is a multiplication
A jet engine never pushes against the sky. There is nothing behind an aircraft to push on. It swallows air and throws it backwards faster than it arrived — and the aircraft feels the equal, opposite shove. That shove is thrust: mass flow times speed change, F = ṁ · Δv.
Grow either number and thrust grows. The GE90-115B — the record-holding engine one generation back — swallows 1,350 kilograms of air every second at takeoff. That is the ṁ. Everything else in this machine exists to make Δv, and to survive making it.
What to watch Slide Δv: the same 1,350 kg/s of air, thrown back faster, multiplies into proportionally more shove — nothing else changes. Cross the red line and the dial reads takeoff: the GE9X's 110,000 lbf rating is nothing but this product at 362 m/s (489 kN ÷ 1,350 kg/s).
ṁ = 1,350 kg/s is GE's published takeoff figure for the GE90-115B. The
dial's kilonewtons are computed on this page: 1,350 × Δv. 1 lbf = 4.448 N.
02The widest fan ever flown
The GE9X's fan is 3.40 metres across — and nearly as wide as the whole fuselage of a Boeing 737, which is 3.76 m. Sixteen hollow composite blades do the work, each sculpted around a steel leading edge. The previous generation's 1.2-metre blade is in the Museum of Modern Art.
At full power the blade tips sweep their 3.4-metre circle 39 times a second — about 420 m/s, faster than sound. The air doesn't get burned yet: ten of every eleven kilograms take the outer road and never meet the fire at all. The machine is an air-mover first and a burner second.
What to watch Both circles share a scale: the dashed 737 body, the solid fan. Slightly narrower — and GE's own page rounds the story up.
The grip
Sixteen blades spin at up to 2,355 rpm; their tips sweep about 420 m/s — supersonic (2π × 1.702 m × 2,355⁄60, computed). The stream splits 10 to 1: for every kilogram of you aimed at the core, ten take the bypass road.
The squeeze
The core climbs fourteen stages — three low-pressure, eleven high — each a pair of rotating and fixed blades. Pressure rises sixty-fold; the passage shrinks as the air densifies; from squeezing alone you are now past 600 °C (ideal-cycle value, computed live on the readouts).
The fire
Fuel injectors light a ring of flame — in a small corner of the stream. Computed from GE's own numbers: one part fuel to about thirty-three parts air, a third as rich as a perfect kerosene flame wants. The rest of the air cools the walls and wraps the fire before it reaches the turbine.
The steal
The hot gas expands through the turbine and spins it — gas beyond 2,000 K, hotter than the blade alloy's own melting point, survived by films of cool compressor air bled through the blades. Each HP blade extracts about 1,000 horsepower, a Formula 1 car's worth — and every one of those horses drives the machinery ahead of the fire.
The exit
The squeezed, heated column accelerates through the narrowing nozzle until its pressure is nearly spent, and leaves fast. That speed change — times 1,350 kilograms per second of it — is the multiplication from the first scene. Thrust is the exhaust of that arithmetic.
04The engine pays for its own air
Here is the part that looks like a paradox: the compressor that feeds the fire is driven by the fire itself. The turbine steals energy from the exhaust and spends it spinning the machinery up front. Nothing outside the engine keeps it running — the loop closes on the inside.
Two shafts make the loop work, one inside the other, at different speeds: the small high-pressure spool at 9,561 rpm, the big fan spool around it at 2,355 rpm. When a pilot pushes the throttle, one spool drags the other up — the fire grows because the squeeze grew, and the squeeze grows because the fire grew.
The turbine pays for the air the fire needs. That closed loop
is the jet engine.
What to watch Both spools turn; the inner dashed ring spins about four times faster — the honest ratio of the GE9X's two shaft speeds.
ACT 05 · PEEBLES, OHIO — OUTDOOR TEST STAND
Every number so far was an intention.
These are measurements.
November 10, 2017. A GE9X development engine runs past every red line at once — maximum fan speed, maximum core speed, maximum gas temperature. On the stand it delivers 134,300 pounds of thrust and a Guinness world record. Rated engines settle for 110,000.
134,300
LBF
Record thrust. GE9X, triple-red-line test, 2017-11-10. The previous
record: 127,900 lbf, GE90-115B, 2003.
5.2 : 1
Thrust to weight. 110,000 lbf of push against 21,230 lb of engine —
computed from the type certificate.
2.3 S
To swallow an Olympic pool. 1,350 kg/s of air is ≈ 1,100 m³/s; the pool
is 2,500 m³. Computed on this page.
ONE
A 747 flew on a single engine. GE's testbed flew with one GE90-115B at
takeoff power, the other three at idle.
POOL ARITHMETIC: 1,350 KG/S ÷ 1.225 KG/M³ (SEA-LEVEL AIR) ≈ 1,100 M³/S. AN OLYMPIC POOL HOLDS 2,500 M³. 2,500 ÷ 1,100 ≈ 2.3 SECONDS.
06Say it in one breath
A jet engine never pushes against the sky. It swallows air, squeezes it sixty-fold, burns a dash of fuel in a corner of it, steals that heat back as shaft power to squeeze harder — and throws the whole column backwards faster than it arrived. Thrust is the arithmetic of that throw: mass times speed change. Everything else — the 3.4-metre fan, the supersonic tips, the cooled blades living above their melting point — is the machine's answer to a single question: how do we make those two numbers bigger?
Verified against the record
| Rev | Date | Entry |
|---|---|---|
| A | 2016-04 | First run — Peebles, Ohio |
| B | 2017-11-10 | 134,300 lbf, Guinness world record, triple-red-line test |
| C | 2020-09-25 | FAA type certificate E00095EN |
| D | 2026-08 | This manual drawn — from type-certificate data, NASA cooling research, and Rolls-Royce's blade foundry |
SOURCES — FAA TYPE CERTIFICATE E00095EN · GE GE90 / GE9X DATASHEETS ·
NASA (TURBINE COOLING) · ROLLS-ROYCE (BLADE CASTING FACILITY) · MoMA (THE FAN BLADE).
STATION READOUTS ARE AN IDEAL CYCLE COMPUTED IN YOUR BROWSER — ISA DAY, γ = 1.4,
TURBINE INLET ASSUMED 1,850 K — NOT MEASURED ENGINE DATA.