Abstract: An external concentrator is disclosed for use in concentrating reflected solar radiation (e.g., beams or rays) onto a heat collection element (HCE) located at a focal point of a parabolic mirror. The external concentrator includes at least first and second elongated ribs that are adapted to extend radially outward from the outside surface of an HCE and along a linear length (e.g., a portion or all) of the HCE to redirect stray/spilled light into the absorber tube of the HCE. The radial extension of the ribs above the outside surface of the HCE allows a reflective surface of the rib to redirect stray reflected beams/rays that would otherwise bypass the HCE back onto the HCE.

Abstract: An aircraft capable of vertical take-off and landing is provided. The aircraft includes a fuselage having a forward portion and an aft portion. A lift fan extends though a duct, which extends through the fuselage. The aircraft further includes a pair of wing sets where each set of wings include first and second wings. Each set of wings has a first wing with a first wing root interconnected to the fuselage forward of a central axis of the lift fan and a second wing having a second wing root interconnected to the fuselage aft of the central axis of the lift fan. The tips of each set of wings are connected. The aircraft further includes a pusher fan.

Abstract: A recuperator for use in transferring heat from gas turbine exhaust gases to compressed air inlet gases before combustion. The recuperator utilizes a plurality of stacked foils that define microchannels to form a recuperator having high effectiveness and low pressure drop while maintaining a low weight. Accordingly, the recuperator presented herein may be incorporated into light aircraft and helicopters without significantly compromising the performance thereof.

Abstract: A vertical take off and landing (VTOL) aircraft, which may be a UAV aircraft, is disclosed. The VTOL is capable of vertical takeoff and landing, hovering and traveling of slow speeds. In addition the VTOL permits high-speed forward flight that allows for increasing the range of the aircraft.