The Seidel ST 525 5-cylinder radial model airplane engine was designed and built by Wolfgang Seidel in Germany in 2000. This is among the largest 5-cylinder model-airplane engines built to date. It measures approximately 12 inches in diameter and 10 inches in length. It weighs approximately 12 pounds with 8 cubic inches (128cc) total displacement. It runs on methanol with spark ignition. This is one of a few that has Wolfgang Seidel’s custom electronic ignition on the back of the engine.