An unmanned aerial vehicle capable of VTOL operation can include: a vehicle body defining longitudinal and transverse directions and opposing longitudinal sides; a first support boom coupled to the vehicle body at a first transverse axis and extending outwardly from the opposing longitudinal sides; a second support boom coupled to the vehicle body at a second transverse axis positioned rearward from the first transverse axis and extending outwardly from the opposing longitudinal sides; a plurality of electric motors coupled to a one of the first and second support booms, at least two electric motors of the plurality of electric motors positioned on each of the first and second support booms, a rotation axis of each of the at least two electric motors coupled to the second support boom offset in a transverse direction from a rotation axis of each of the at least two adjacent electric motors coupled to the first support boom; a plurality of rotors; and a propulsion system.

A hybrid propulsion system for a vertical take-off and landing aircraft comprising at least one combustion engine driving an electricity generator, at least one electrical energy storage assembly associated with each electricity generator and defining, with each electricity generator, an energy branch, a plurality of electric motors actuating a same plurality of rotors providing together the propulsion and/or the lift of the aircraft, and an electrical power and distribution unit supplying power to the plurality of electric motors from the electricity generator and/or from the electrical energy storage assembly according to a pre-established flight phase, the system including at least two energy branches having an asymmetric configuration and each supplying power selectively, by means of the electrical power and distribution unit, all or part of the plurality of electric motors, and in that the electricity generators of the combustion engines have between them a power ratio comprised between.

A hybrid propulsion system for a vertical take-off and landing aircraft comprising at least one combustion engine driving an electricity generator, at least one electrical energy storage assembly associated with each electricity generator and defining, with each electricity generator, an energy branch, a plurality of electric motors actuating a same plurality of rotors providing together the propulsion and/or the lift of the aircraft, and an electrical power and distribution unit supplying power to the plurality of electric motors from the electricity generator and/or from the electrical energy storage assembly according to a pre-established flight phase, the system including at least two energy branches having an asymmetric configuration and each supplying power selectively, by means of the electrical power and distribution unit, all or part of the plurality of electric motors, and in that the electricity generators of the combustion engines have between them a power ratio comprised between.

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.

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.

A muffler (40) devised particularly for use with an engine of the type used on unmanned aerial vehicles (UAVs), and a UAV (10) having an engine (30) fitted with the muffler (40). The muffler (40) comprises a body (51) having an interior chamber (60). The muffler body (51) has a first end section (53) and a second end section (55). The first end section (51) is adapted for mounting onto the engine (31) by way of a first mount (81), with the interior chamber (60) in communication with an exhaust outlet of the engine (31) to receive exhaust flow therefrom. The second end section (53) is adapted to be mounted by way of a second mount (82) in a manner resisting movement with respect to the engine (31). In one arrangement, the second mount (82) is configured to yieldingly resist movement with respect to the engine (30). In another arrangement, the second mount (82) is configured to mount the second end section (55) under a preload resisting movement of the second end section with respect to the engine (30).

A muffler (40) devised particularly for use with an engine of the type used on unmanned aerial vehicles (UAVs), and a UAV (10) having an engine (30) fitted with the muffler (40). The muffler (40) comprises a body (51) having an interior chamber (60). The muffler body (51) has a first end section (53) and a second end section (55). The first end section (51) is adapted for mounting onto the engine (31) by way of a first mount (81), with the interior chamber (60) in communication with an exhaust outlet of the engine (31) to receive exhaust flow therefrom. The second end section (53) is adapted to be mounted by way of a second mount (82) in a manner resisting movement with respect to the engine (31). In one arrangement, the second mount (82) is configured to yieldingly resist movement with respect to the engine (30). In another arrangement, the second mount (82) is configured to mount the second end section (55) under a preload resisting movement of the second end section with respect to the engine (30).

An aircraft piston engine magneto having a magnetic rotor and an ignition circuit with a reconfigurable charging coil inductively coupled to magnetic rotor. The charging coil includes multiple coils inductively powered by the magnetic rotor and electronically reconfigurable from a higher turn, lower amperage power coil for use when running at low speeds into a lower turn, higher amperage coil at higher speeds. The charging coil is configured into the higher turn coil by electronically connecting the multiple coils in series, and into the lower turn power coil by electronically connecting the coils in parallel. The ignition circuit is a fully electronic ignition circuit that generates and distributes ignition pulses to the piston engine spark plugs using only non-mechanically actuated electrical components within the magneto.