An improved air-cooled aviation engine includes a compact combustion chamber having an intake valve opening, an exhaust valve opening, and a generally elliptical shape. The elliptical shape has a major axis and a minor axis, with the major axis intersecting both the intake valve opening and the exhaust valve opening. In some examples, the major axis is the same length or shorter than a diameter of a cylinder bore of the engine, and the minor axis is smaller than the major axis. Combustion is thus constrained to a smaller area than that of the cylinder bore.

An improved air-cooled aviation engine includes a compact combustion chamber having an intake valve opening, an exhaust valve opening, and a generally elliptical shape. The elliptical shape has a major axis and a minor axis, with the major axis intersecting both the intake valve opening and the exhaust valve opening. In some examples, the major axis is the same length or shorter than a diameter of a cylinder bore of the engine, and the minor axis is smaller than the major axis. Combustion is thus constrained to a smaller area than that of the cylinder bore.

According to one implementation, a centrifugal oil mist separator includes a duct, a fan and a power transmission mechanism. The duct forms a flow path of a first exhaust gas discharged from an engine. The first exhaust gas includes oil mist. The fan is disposed inside the duct. The power transmission mechanism rotates the fan using energy of a second exhaust gas discharged from the engine. The second exhaust gas includes no oil mist.

According to one implementation, a centrifugal oil mist separator includes a duct, a fan and a power transmission mechanism. The duct forms a flow path of a first exhaust gas discharged from an engine. The first exhaust gas includes oil mist. The fan is disposed inside the duct. The power transmission mechanism rotates the fan using energy of a second exhaust gas discharged from the engine. The second exhaust gas includes no oil mist.

An autonomous unmanned aerial vehicle for land, sea and air use. The autonomous unmanned aerial vehicle is more specifically related to an unmanned aerial vehicle, wherein the autonomous unmanned aerial vehicle is configured to vertically take off and vertically land, fly with fixed wings and stay in the air silently for a long time by means of a balloon inflated behind it.

An autonomous unmanned aerial vehicle for land, sea and air use. The autonomous unmanned aerial vehicle is more specifically related to an unmanned aerial vehicle, wherein the autonomous unmanned aerial vehicle is configured to vertically take off and vertically land, fly with fixed wings and stay in the air silently for a long time by means of a balloon inflated behind it.

Variations of an aerial vehicle, all with capability of vertical take-off and landing (VTOL), with one variation comprising at least three engines, at least three rotors, a flight control system, battery, and propulsion system. The second VTOL aerial vehicle variation being a hybrid with engine-powered rotors and electric-powered rotors configured to work with a flight control system and battery. The first and second variations having the option of a genset system which recharges the battery. The third VTOL aerial vehicle variation being all-electric-powered rotors configured to work with a flight control system and a genset system which powers the rotors and/or recharges the battery.

Variations of an aerial vehicle, all with capability of vertical take-off and landing (VTOL), with one variation comprising at least three engines, at least three rotors, a flight control system, battery, and propulsion system. The second VTOL aerial vehicle variation being a hybrid with engine-powered rotors and electric-powered rotors configured to work with a flight control system and battery. The first and second variations having the option of a genset system which recharges the battery. The third VTOL aerial vehicle variation being all-electric-powered rotors configured to work with a flight control system and a genset system which powers the rotors and/or recharges the battery.

An aircraft engine has a hollow driveshaft with a spool coaxial with the driveshaft and extending through the driveshaft to rotate independently of the driveshaft. A first harmonic cam is mounted on the driveshaft and a second spaced apart harmonic cam is mounted on the spool. At least one combustion cylinder is positioned between the cams along a combustion cylinder axis that is parallel with but radially spaced apart from the driveshaft. A piston assembly is disposed in each end of the combustion cylinder, with each piston assembly engaging a separate cam. A high-pressure compressor turbine is mounted on the driveshaft and driven by movement of a piston assembly, compressing air for the combustion cylinder. A rotating component is mounted on the spool and driven by movement of the other piston assembly. The rotating component may be another compressor turbine, a drive turbine, a fan or a propeller.

An aircraft engine has a hollow driveshaft with a spool coaxial with the driveshaft and extending through the driveshaft to rotate independently of the driveshaft. A first harmonic cam is mounted on the driveshaft and a second spaced apart harmonic cam is mounted on the spool. At least one combustion cylinder is positioned between the cams along a combustion cylinder axis that is parallel with but radially spaced apart from the driveshaft. A piston assembly is disposed in each end of the combustion cylinder, with each piston assembly engaging a separate cam. A high-pressure compressor turbine is mounted on the driveshaft and driven by movement of a piston assembly, compressing air for the combustion cylinder. A rotating component is mounted on the spool and driven by movement of the other piston assembly. The rotating component may be another compressor turbine, a drive turbine, a fan or a propeller.