Definition
A turbine engine compressor arrangement in which incoming air passes through two separate compressor sections in series, each driven independently, so the air is compressed in two successive steps before reaching the combustion section.
Plain English
An engine setup where the air is squeezed in two stages, one after the other, instead of all at once. Each stage builds on the pressure from the one before it.
Context Anchor
Seen in turboprop engine descriptions when learning how the engine takes in air, compresses it, burns fuel, and produces power.
Derivation
From 'stage,' meaning a step in a process, and 'compressor,' a device that squeezes air into a smaller volume. Two-stage simply means the squeezing happens in two steps rather than one.
Why Pilots Care
The two-stage design delivers higher pressure ratios, improving power output and fuel efficiency across a wider range of altitudes and power settings.
Intuition Check
Do not read stage as a phase of flight or a pilot-selected setting. Here, a stage is one pressure-increasing step inside the engine.
Example Sentence 1
The PT6 turboprop uses a two-stage compressor, with the air first passing through axial stages before reaching the centrifugal stage.
Example Sentence 2
During the preflight, the pilot noted that the two-stage compressor required careful monitoring of TIT to avoid exceeding temperature limits.