Which type of plane is specifically used for smoothing long straight surfaces?

The smoothing plane is designed specifically for achieving a fine finish on wood surfaces. This tool is used after initial shaping and jointing to create a smooth, even surface by removing slight imperfections and refining the texture. Its iron is set at a shallow angle to cut fine shavings, allowing for delicate work to enhance the appearance of the wood.

While other planes like the block plane, jack plane, and rabbet plane serve specific purposes in woodworking—such as trimming end grain, general purpose planing, or creating grooves and rabbets—the smoothing plane excels at providing the final touch to surfaces, making it the appropriate choice for tasks that involve smoothing long straight areas.