Next generation General Aviation (GA) Sport Class air vehicles limited to 1200lbs, represent the first opportunity to overhaul the FAA certification process necessary to manufacture affordable aircraft. With propulsion representing over one-third of the direct manufacturing costs of the entire aircraft, dramatic reductions in aircraft engine costs must be achieved by design, economy of scale, and modern Quality Assurance (QA) manufacturing techniques. Future on-demand intra-urban Personal Air Vehicles (PAV) will require a breakthrough in affordable ($20/hp) propulsion technology capable of STOL or VTOL performance with specific weight ratio above 1hp/lb. Affordable engines of this performance do not exist today. Therefore this propulsion system study proposes to examine 3 innovative concepts of widely different configurations, namely: Advanced Uniflow Supercharged 4-cycle; Advanced Contra-Prop Supercharged 2-cycle; and Free Piston/Turbine designs. The common design philosophy of maximum breathing capacity, unobstructed combustion chamber design, and high mechanical/structural efficiency ensures maximum power density on multi-fuels at the lowest cost. Economy of scale and QA production are approached by innovative/universal design that is aligned with recreational engine power and manufacturing practices.