Abstract: An electric aircraft includes a forward wing and an aft wing both located on a top side of a fuselage and both having an upward dihedral angle. The forward wing has a straight or slightly forward-swept leading edge. The aft wing has a swept leading edge. A plurality of propeller engines are located on a leading-edge side of the forward wing. A single propeller engine may be located on a top side of an aft end of the fuselage; alternatively, a plurality of propeller engines are located on the aft wing on either its leading or trailing edge. The propeller engines are each powered by an electric motor. An unobstructed cargo door is located on a side of the fuselage, aft of the forward wing.

Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic attenuation structure includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: A noise attenuation panel for a structure within a propulsion system includes a first plurality of unit cells; and a second plurality of unit cells, the second plurality of unit cells merged within the first plurality of unit cells, the first plurality of unit cells including a first periodic structure having a first unit cell, a second unit cell, a third unit cell and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells.

Abstract: A noise and vibration attenuation panel for a structure within a propulsion system includes a first plurality of unit cells and a first plurality of mass elements disposed within the first plurality of unit cells. The first plurality of unit cells include a first periodic structure having a first unit cell, a second unit cell, a third unit cell, and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells. The noise attenuation panel can simultaneously control acoustic waves or energy (i.e., via noise attenuation flow paths) and vibration (i.e., via the mass elements).

Abstract: A waterjet-guided laser machine includes a laser source, an LED, a waterjet head, and a light sensor. The waterjet head includes a water inlet and a nozzle having an outlet for a discharging a waterjet. There is a laser optical path along which a pulsed laser beam travels to the nozzle outlet. There is also a light beam optical delivery path along which the light beam travels from the LED to the nozzle outlet. The light beam optical delivery path is coincident with the laser optical path in the nozzle. There is a light beam optical return path along which the light beam that is reflected off of a workpiece travels to the light sensor. The light beam optical return path is coincident with the laser optical path inside the nozzle and coincident with the light beam optical delivery path inside the nozzle.

Abstract: A noise attenuation panel for a structure within a propulsion system includes a first plurality of unit cells; and a second plurality of unit cells, the second plurality of unit cells merged within the first plurality of unit cells, the first plurality of unit cells including a first periodic structure having a first unit cell, a second unit cell, a third unit cell and a fourth unit cell, each of the first unit cell, the second unit cell, the third unit cell and the fourth unit cell including a central body interconnected via a plurality of lateral tubes extending from the central body, the first periodic structure forming a first lateral layer of unit cells.

Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic attenuation structure includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: An acoustic attenuation structure for a gas turbine engine includes a periodic structure having a first unit cell, the first unit cell having a first central body and a first axial tube disposed on the first central body and a second axial tube disposed on the first central body, opposite the first axial tube, each of the first axial tube and the second axial tube being in fluid communication with one another through the first central body.

Abstract: Various systems and methods are provided for utilizing a crankshaft lip seal over the course of a first overhaul life and a second overhaul life. In one example, a method includes installing the crankshaft lip seal between a flywheel housing and a crankshaft of an engine and operating the engine with the crankshaft lip seal. The method further includes removing the crankshaft lip seal, re-machining a floating seal sleeve coupled to the crankshaft or the flywheel housing, and replacing a lip. The crankshaft lip seal is then re-installed between the flywheel housing and the crankshaft and the engine operated with the re-installed crankshaft lip seal.

Abstract: Various systems are provided for a charge-air cooler system. In one example, a system includes a turbocharger system having at least one compressor and one turbine and configured to provide charge air to an engine. The system also includes a charge-air cooler system having at least one charge-air cooler arranged below the at least one compressor, a turbocharger bracket arranged directly below the charge-air cooler system and shaped to mount the charge-air cooler and the turbocharger system to the engine, and a stator adapter physically coupling an alternator to the engine. The stator adapter includes an accessibility window arranged below the charge-air cooler system. The at least one charge-air cooler is closer to the accessibility window than the turbocharger system.

Abstract: Various systems and methods are provided for utilizing a crankshaft lip seal over the course of a first overhaul life and a second overhaul life. In one example, a method includes installing the crankshaft lip seal between a flywheel housing and a crankshaft of an engine and operating the engine with the crankshaft lip seal. The method further includes removing the crankshaft lip seal, re-machining a floating seal sleeve coupled to the crankshaft or the flywheel housing, and replacing a lip. The crankshaft lip seal is then re-installed between the flywheel housing and the crankshaft and the engine operated with the re-installed crankshaft lip seal.

Abstract: Systems are provided for a mounting assembly providing structural support to a pair of turbocharger and charge air coolers. In one example, the mounting assembly may include support brackets and pedestals for coupling the turbochargers and the charge air coolers to one structure. Separate channels for applying lubricant and coolant to the turbochargers and the charge air coolers may be coupled to the mounting assembly.

Abstract: Various systems are provided for a charge-air cooler system. In one example, a system includes a turbocharger system having at least one compressor and one turbine and configured to provide charge air to an engine. The system also includes a charge-air cooler system having at least one charge-air cooler arranged below the at least one compressor, a turbocharger bracket arranged directly below the charge-air cooler system and shaped to mount the charge-air cooler and the turbocharger system to the engine, and a stator adapter physically coupling an alternator to the engine. The stator adapter includes an accessibility window arranged below the charge-air cooler system. The at least one charge-air cooler is closer to the accessibility window than the turbocharger system.

Abstract: Systems are provided for a mounting assembly providing structural support to a pair of turbocharger and charge air coolers. In one example, the mounting assembly may include support brackets and pedestals for coupling the turbochargers and the charge air coolers to one structure. Separate channels for applying lubricant and coolant to the turbochargers and the charge air coolers may be coupled to the mounting assembly.

Abstract: Various systems are provided for a charge-air cooler system. In one example, a system includes a turbocharger system having at least one compressor and one turbine and configured to provide charge air to an engine. The system also includes a charge-air cooler system having at least one charge-air cooler arranged below the at least one compressor, a turbocharger bracket arranged directly below the charge-air cooler system and shaped to mount the charge-air cooler and the turbocharger system to the engine, and a stator adapter physically coupling an alternator to the engine. The stator adapter includes an accessibility window arranged below the charge-air cooler system. The at least one charge-air cooler is closer to the accessibility window than the turbocharger system.