Infinity's High Efficiency Advanced Lightweight Fuel Cell (HEAL FC) is an improved version of its current fuel cell technology developed for space applications. The fundamental operation of this Proton Exchange Membrane (PEM) fuel cell is improved over comparable fuel cell technologies, providing simplified system design and longer duration missions. The Non Flow Through (NFT) nature of reactant consumption within the fuel cell stack produces a much higher utilization of reactants. The Advanced Product Water Removal (APWR) embodied within each repeat element of the fuel cell stack allows for the elimination of the water separation devices usually residing in the balance of system. This drives system simplification while increasing overall reliability and reducing system cost. The HEAL FC can be operated as a hydrogen-oxygen fuel cell for long endurance missions and also as a hydrogen-air fuel cell. This transition from pure oxygen to air can be accomplished dynamically in flight, allowing for reduced mass of the oxygen storage subsystem. This is a critical advantage for UAS flying to and from dense air environments consuming air as the fuel cell oxidant and switching over to pure oxygen when in the dense air region of concern. The fuel cell stack improvements to be made as part of this topic are planned to make the fuel cell stack more amenable to Unmanned Aerial Systems (UAS) by reducing mass and volume. The current configuration of the fuel cell stack was driven by performance only. Now that the NFT and APWR technologies have been proven, the stack hardware itself must be minimized to fit the UAS markets. Costs for this advanced fuel cell system will inherently be reduced through the implementation of mass production design methodology to transform a well-functioning power system for space applications to lower altitude uses.