FLEDERMAUSER (ger) means “Bats” or “of Bats” and is a registered trademark. The aircraft is inspired by the agile flight characteristics, purposeful appearance and diverse roles of mammals of the order ‘Chiroptera’.


  • The Fledermauser is an optionally crewed VTOL aircraft designed to provide multirole organic airpower for austere operations.
  • Primary features include a turbine-electric powerplant, a patented fixed ducted wing VTOL system, an open central payload bay, dual sensor stations and robust quad landing gear.
  • The unique Fledermauser configuration potentially provides a higher degree of speed, safety, resilience and variable sound mitigation compared to open rotor systems of similar weight and technology level.
  • Utility and Design Patents Pending
  • The Fledermauser aircraft is currently under development by Sierra Technical Services, Inc. in Tehachapi, California


FM1, scaled to 6 inch diameter Electric Ducted Fans, is the smallest concept design.  The size is driven by the intersection turbo-generator efficiency, available payload and achievable forward airspeed, compared to other UAS of similar size and expense. At this scale, it is depicted conducting missions similar to the U.S. Navy MQ-8B, because it provides the closest operational analogy for refining it’s mission potential.  However it would be adaptable to a range of  ship-to-shore and land-based missions..


FM2, scaled to 9 inch diameter Electric Ducted Fans, is the medium concept design. This size is driven by the minimum space needed to perform unattended CASEVAC missions.  The size of FM2 also derives greater efficiency from current hybrid technology, which can be utilized to integrate a broader range of mission systems such as a vertical payload winch. FM2 is depicted performing land-based missions, providing organic airpower to manpower-intensive units that would otherwise have  little aerial fires or logistical support. 


FM3, scaled to 12 inch diameter Electric Ducted Fans is the largest concept design. The size is driven by the size of commercially mature Electric Ducted Fan technology, and the size of turbine electrical generators currently planned by industry leaders for commercial UAM markets.  The payload and internal volume of FM3 makes missions with up to three people possible; expanding it’s utility to civil and commercial applications where safety, speed and resilience are high priorities. 


All Fledermauser concept designs share the same outer mold line and basic configuration, but at different scales.  It is expected that system architecture will be the same across this size range. The dynamic components such as Electric Ducted Fans, servos, actuators are scaled differently in each size aircraft, but the location and functions are the same.  Mission related systems and access panels will be different.  Therefore, the FM2 concept design shown in the illustrations and diagrams (below) provides a solid technical description for understanding the basic technical aspects of Fledermauser.