Compressor Design

Turboprop

• Medium-speed

•Moderate-size craft

•High efficiency

•Limited flight speed

•Geared transmission

Turbofan

• Internal Propeller

• Supersonic speeds

• High bypass airflow

• Med/High efficiency

• No gearbox

Turbojet

• High speed

• Mach 4

• Low airflow rate

• Low efficiency

• High op temps

Turbo Engine Comparison

NOTE: Due to the ram compression due to flight speed, the optimum compressor pressure ratio (CPR) goes to zero around Mach 4.

CPR 30:1 for subsonic flight.

CPR 10:1 @ Mach 2.

Compressor not needed at Mach 4; Ramjet.