ELAS (Electric Lift Augmenting Slats) is an eSTOL technology that combines leading-edge slats with a series of small electric ducted fans (EDFs) accelerating the air between the slat and the airfoil. The core of the ELAS concept is the combination of two technologies.
In 2016 CubCrafters began experimenting with a specialized leading-edge slat to lower the takeoff speed and distance of their aircraft and enhance low-speed maneuverability. Analysis as done using CFD, with units built and flight-tested on a manned research aircraft. The stock craft could take off in 100' with the slat lowering this by 35%. This technology has resulted in a patent disclosure and is at TRL 5.
Parallel to, and independent of the CubCrafters Slat project, Ullman (PI) also began a privately funded project in 2016 to study Electric Ducted Fans (EDFs) enhancing the upper surface flow much like the Boeing's YC-14 and NASA QSRA, but with distributed electric propulsion.
Extensive wind-tunnel testing showed increases in all lift curve characteristics, Clo, Cla, and Clmax. Typical Clmax increases of 117% were seen, implying a potential halving of the takeoff distance. In-flight tests with the JabirWatt (a Jabiru J260 modified for the project), with its 12% EDF coverage, showed a 16% increase in Clmax, resulting in an 8% decrease in the stall speed. This project has resulted in a patent, Distributed Electric Ducted Fan Wing (10,099,793), October 2018, and is currently at TRL5.
The combination of these two technologies in ELAS has potential greater than the sum of their parts but is at TRL 1-2. ELAS's potential will be explored in the proposed research with the development of a baseline configuration complete with performance estimates for a STOL mission and CFD tools for future optimization bringing the concept to TRL 3-4
Beyond the evident importance to CubCrafters, potential applications within NASA include humanitarian aid delivery via aircraft requiring STOL capability; development of a low-cost aerial vehicle for exploration with acquisition and operation costs less than many unpiloted vehicles currently in use; and ELAS application for advanced off-field capability with piloted, optionally-piloted, and unpiloted CubCrafters aircraft. From a research perspective, ELAS is a distributed electric propulsion QSRA technology.
For CubCrafters and other STOL manufacturers, market drivers are centered on aircraft that provide true STOL performance while also offering best in class useful load and cruise speeds. By the core nature of this innovation's purpose, ELAS is directly positioned to enhance all aspects of STOL operations: takeoff, climb, approach and landing, enabling further utility and larger safety margins