Why the Lack of Small, Light Weight Aircraft Engines

Even though we are all actively engaged in programs concerning the planning and building of large aircraft, the fact, cannot be overlooked that small aircraft are demanding more and more attention. By way of definition in this writing, the term "small aircraft" will represent a flying machine capable of lifting one man off of the ground (and flying with forward velocity in most cases), or a machine of comparable size, performance, and gross weight without a man aboard. These small machines are suffering from one common illness - lack of light weight engines. The advancements which are being made in large aircraft are not being duplicated in small aircraft.