Aviation Engine Performance and Mechanics

A collection of vocabulary terms regarding piston engine components, stroke cycles, firing intervals, and detonation procedures based on lecture notes.

Compression rings

The top two rings that maintain cylinder pressure and prevent gas leaks.

Oil ring

The bottom ring used to prevent oil passage and coat cylinder walls with an oil film.

Piston ring heat transfer

The process where all rings transfer heat from the piston to the cylinder fins.

Power Stroke

The only stroke of the four that delivers power to the crankshaft, often referred to as "BANG".

Exhaust Stroke

Referred to as "BLOW", where the piston forces burnt gases out of the open exhaust valve.

Ignition Timing Spark Placement

The requirement for spark plugs to fire before the point where best pressure is required, allowing the fuel-air charge finite time to burn and expand.

Torque vs. Crank Throw Arm (Small)

A smaller arm that needs more force compared to a larger arm.

Torque vs. Crank Throw Arm (Large)

A larger arm that needs less force compared to a smaller arm.

Firing Interval Formula

Divide $720^\circ$ by the number of cylinders.

4-Cylinder Firing Interval

Fires every $180^\circ$.

6-Cylinder Firing Interval

Fires every $120^\circ$.

8-Cylinder Firing Interval

Fires every $90^\circ$.

Detonation Symptoms

Rising engine temperature, power loss, and engine vibration/knocking.

Detonation Pilot Action (Mixture)

Place mixture control to fully rich position for immediate fuel cooling.

Detonation Pilot Action (Engine Control)

Reduce power, open cowl flaps, and increase climb IAS.

Take-Off Power Rating Limit

Approved for limited periods, usually $3$ to $5$ minutes.

Take-Off Power Rating Characteristics

Represents more than $100\%$ MCP and requires a fully rich mixture to ensure adequate engine cooling.