Why do some aircraft engine manufacturers use choked or taper-ground cylinders?

Using choked or taper-ground cylinders in aircraft engines primarily serves the purpose of providing a straight cylinder bore at operating temperatures. As the engine operates, it generates heat, which can cause the materials to expand. If the cylinder bores are not perfectly straight, the thermal expansion could lead to uneven contact between the piston and cylinder wall, resulting in increased friction, wear, and potentially reduced engine efficiency.

By designing the cylinders to be tapered or choked, the manufacturers ensure that even when the engine heats up and the materials expand, the shape of the cylinder maintains a more consistent diameter along its length. This helps to minimize distortion, ensuring that the bore remains as straight as possible during operation. The result is improved sealing between the piston and cylinder wall, leading to better combustion efficiency and overall engine performance.

The other options do not accurately reflect the primary intent of using choked or taper-ground cylinders. For instance, while reducing engine weight and enhancing engine operation smoothness may be beneficial outcomes, they are not the primary reasons for adopting this specific cylinder design. Likewise, increasing bore diameter for better airflow is not relevant to the taper-ground design, as it is focused on maintaining bore straightness rather than modifying diameter.