How is 'compression ratio' defined in the context of aircraft engines?

Compression ratio in the context of aircraft engines is defined as the ratio of maximum cylinder volume to minimum cylinder volume. This measurement is critical because it indicates the extent to which the fuel-air mixture is compressed in the cylinder before ignition occurs. A higher compression ratio usually results in more efficient engine operation and greater power output because it allows the engine to extract more energy from the fuel. By understanding this concept, one can grasp how compression contributes to the overall performance and efficiency of the engine.

The other choices, while related to various aspects of engine performance, do not accurately describe compression ratio. The difference between power outputs pertains to engine performance but does not relate to cylinder volumes. Similarly, the relationship between the fuel and air mixture is crucial for combustion efficiency but does not define compression ratio directly. Engine displacement, on the other hand, refers to the total volume displaced by all pistons in the cylinders, which is an entirely different concept.