What is the correct order of operation for a typical four-stroke cycle airplane engine?

The four-stroke cycle of an airplane engine consists of four distinct phases: intake, compression, power, and exhaust.

During the intake phase, the engine's intake valve opens, and the piston moves down the cylinder, drawing in an air-fuel mixture. This is crucial as it begins the process of getting the necessary ingredients for combustion.

Next is the compression phase, where the piston moves back up the cylinder with both valves closed, compressing the air-fuel mixture. This compression raises the temperature and pressure, making it more efficient for ignition.

Following compression is the power phase. At this point, a spark plug ignites the compressed air-fuel mixture, causing an explosion that pushes the piston down, generating power for the engine. The conversion of fuel to energy happens here, which is central to the engine's operation.

Finally, in the exhaust phase, the exhaust valve opens, and the piston moves back up to expel the burning gases from the engine's cylinder. This clears the way for the next intake phase cycle to begin anew.

Understanding the sequence of these phases is essential for grasping how a four-stroke engine operates and efficiently converts fuel into mechanical energy.