30-05-2012, 11:26 AM
High Performance Piston Engine Operations
High Performance Piston Engine Operations.ppt (Size: 1.17 MB / Downloads: 79)
Propeller Basics
Like any airfoil, the propeller is most efficient at a specific angle of attack
As the forward speed and RPM’s change, the relative wind experienced by the propeller comes from different angles
The propeller changes its blade angle (pitch) so the AOA remains optimal
Engine Basics- Engine Controls
Throttle-
Moves throttle plate
Constricts air to engine, effectively reducing power
Propeller
Adjusts tension on speeder spring
Sets equilibrium RPM
Mixture
Moves fuel proportioning valve
Changes fuel-air ratio sent to engine
Cirrus Power Lever
First portion of travel adjusts propeller only- throttle remains full open.
Then throttle is progressively closed, propeller left unchanged.
Benefits of Operating Lean of Peak
More Fuel Efficient (Better BSFC)
Decreased CHT’s for same power
Lower Pressure in Cylinders for same power
Cleaner Combustion
Lower Deposits
Less “Washdown” of Cylinders
Less Carbon Monoxide Production
Definition of Terms
Exhaust Gas Temperature (EGT)
Temperature of burned fuel and air charge,
Measured as it exits the cylinder,
Value not usually important, but rather indication relative to other EGT’s or to peak EGT.
Cylinder Head Temperature (CHT)
Temperature of each cylinder,
Value is important- lower temperatures are better,
Affected by power, mixture, airflow over the cylinders.