Jet Engine Cross-Section (2D)

Engine Controls

Throttle 40%

Bypass ratio 6.0 : 1

Idle — spool up the throttle to generate thrust.

Live Readout

Net thrust

— kN

Total mass flow

— kg/s

Core exhaust v

— m/s

Bypass exit v

— m/s

Fan / LP spool N1

— rpm

Core / HP spool N2

— rpm

Combustor EGT

— °C

Core mass flow

— kg/s

How it works

A turbofan makes thrust the way any rocket or propeller does: by Newton's third law. The engine accelerates a mass of air rearward, and the equal, opposite reaction pushes the airframe forward. Net thrust F = ṁ_core·(V_core − V₀) + ṁ_bypass·(V_bypass − V₀), where ṁ is mass flow rate, V is exhaust velocity and V₀ is the incoming air speed (zero for this static test-stand view).

Air enters through the intake, and a large fan immediately splits it in two: most of it skips the hot section entirely as bypass flow, squeezed only a little before rejoining at the nozzle. The rest enters the core, where axial compressor stages raise its pressure many-fold before fuel is added and burned in the combustor, releasing energy as a hot, high-pressure gas.

That gas expands through the turbine stages, spinning them — and because the turbine shares a shaft with the compressor and fan ahead of it, the expanding gas is literally what drives the compression and bypass fan upstream. What's left of the gas's energy accelerates it out the exhaust nozzle. Raising the bypass ratio shifts more air into the cool, efficient bypass duct — real high-bypass turbofans get roughly 80% of their thrust from bypass air, not the fiery core.

Bypass air — cool, fast Core air — compressed Combustion gas — hot