Every jet engine, from the massive turbofans on a passenger plane to the compact turbines in a helicopter, operates on a fundamental thermodynamic principle: the Brayton cycle. While the real-world mechanics are incredibly complex, we can understand the core process by analyzing an idealized version. This ideal cycle strips away complexities like friction to reveal the engine's theoretical limits.

Think of it as the physics behind the familiar "Suck, Squeeze, Bang, Blow" sequence. The Brayton cycle models how an engine takes in air, compresses it, adds energy by burning fuel, and then extracts power by expanding the hot gas. We can visualize this entire process on two key diagrams: a Pressure-Volume (P-V) diagram and a Temperature-Entropy (T-S) diagram.