Current VTOL UASs in development, and concepts being pursued by both commercial and military operators, require high-power delivery on takeoff and landing segments. This duty can be served with a special purpose ultra-lightweight gas turbine-alternator. For this short duty cycle, the relaxed SFC requirement opens opportunities for weight reduction strategies. This FOAs specification for electric power/weight ratio of 2 hp/lb is extremely demanding, roughly twice that of Braytons existing GT35 kWe recuperated microturbine alternator and about 4X that of commercial microturbines in this power class. However, the SFC target is considerably more lenient. Upon close inspection, meeting the Navy lightweight specification is not possible by simplifying dropping the recuperator from our GT35. Meeting the > 2 hp/lb specification requires a departure from conventional microturbine design formula. With heavy emphasis on weight over efficiency, Braytons design adopts two foundational principles; maximize speed-power product for the alternator and maximize the turbine inlet temperature.
