A distributed propulsion system is described that includes at least one turbine engine including an engine shaft and at least one mechanically driven propulsor, wherein a propulsor shaft of the at least one mechanically driven propulsor is not co-axial with the engine shaft of the at least one turbine engine and is driven by the engine shaft of the at least one turbine engine. The distributed propulsion system further includes at least one generator driven by rotation of at least one of the engine shaft of the at least one turbine engine or the propulsor shaft of the at least one mechanically driven propulsor. The distributed propulsion system also includes at least one electrically driven propulsor, wherein a propulsor motor of the at least one electrically driven propulsor drives a propulsor fan of the at least one electrically driven propulsor based on electricity produced by the at least one generator.

A vertical take-off and landing aircraft using a hybrid electric propulsion system includes an engine, a generator that produces electric power using power supplied by the engine, and a battery that stores the produced electric power. A motor receives the electric power stored in the battery and electric power produced by the generator but not stored in the battery and provides the power to a thrust generating apparatus. A controller selects either silence mode or normal mode, and determines the amount of electric power stored in the battery and the amount of electric power not stored in the battery from the electric power supplied to the motor. In the silence mode, the controller supplies only the electric power stored in the battery and controls a duration by adjusting output power of motor. In the normal mode, the controller supplies electric power not stored in the battery.

Systems and method for an electrical system on an aircraft are provided. In example embodiments, the electrical system can be for an aircraft having a turbine engine. The turbine engine having a high pressure (HP) spool and a low pressure (LP) spool. The HP spool can be configured to drive a first generator to provide a first electrical output. The LP spool can be configured to drive a second generator to provide a second electrical output. The first generator and the second generator can be coupled to an electrical power distribution bus that provides electrical power to a load. A hybrid electric propulsion system and a secondary aircraft systems bus can both be coupled to the electrical power distribution bus. The electrical system can further include a control system configured to allocate power among the first generator, the second generator, and the hybrid electric propulsion system, and the secondary aircraft systems bus.

A computer-implemented method, system, and/or computer program product optimizes an operation of an aerial drone. A drone on-board computer on an aerial drone receives sensor readings from sensors on the aerial drone, where the sensor readings detect a change in flight conditions while the aerial drone is flying between a first location and a second location. In response to the sensors on the aerial drone detecting a change in the flight conditions while the aerial drone is flying between the first location and the second location, the drone on-board computer disengages an electric motor from propellers on the aerial drone and engages an internal combustion engine to the propellers.

A propulsion system includes an electric propulsor and a gas turbine engine. The propulsion system also includes an electric machine coupled to a rotary component of the gas turbine engine generating a voltage at a baseline voltage magnitude during operation of the gas turbine engine. An electric communication bus is provided electrically connecting the electric machine to the electric propulsor. The propulsion system additionally includes a means for providing a differential voltage to the electric propulsor equal to about twice the baseline voltage magnitude.

An unmanned aircraft includes a propulsion system having a diesel or kerosene internal combustion engine and a charger device for engine charging. The propulsion system can be a hybrid propulsion system or a parallel hybrid propulsion system.

An aeronautical propulsion system includes a fan having a plurality of fan blades rotatable about a central axis and defining a fan pressure ratio, FPR. The propulsion system also includes an electric motor mechanically coupled to the fan for driving the fan, the electric motor including a number of poles, n.sub.poles, and defining a maximum power, P. The relationship between the fan pressure ratio, FPR, of the fan, the number of poles, n.sub.poles, of the electric motor, and the maximum power, P, of the electric motor is defined by an equation:

[00001]$\frac{n_{\mathrm{pole}}}{\sqrt{P}}=C_1.Math.e^{-9.062.Math.\mathrm{FPR}}+C_2.Math.e^{-1.2604.Math.\mathrm{FPR}};$

wherein C.sub.1 is a constant having a value between 22,000 and 52,000, wherein C.sub.2 is a constant having a value between 4.0 and 9.8, and wherein e is Euler's number.

An apparatus including a fixed part, a rotary support configured to be driven in rotation relative to the fixed part, at least one item of electrical equipment carried by the rotary support, and a power supply device configured to supply electrical energy to the electrical equipment. The power supply device includes an asynchronous machine including a stator fixed to the fixed part and a rotor carried by the rotary support, and an excitation device. The stator includes an electrical circuit including at least one switch configured to switch between an open state in which the electrical circuit is open and a closed state in which the electrical circuit is closed. The rotor includes at least one winding connected to the electrical equipment. The excitation device is configured to provide a reactive current to the electrical circuit of the stator or to the winding of the rotor.

Multiple motors may drive (rotate) a single shaft coupled to a propeller. The motors may be selected such that a first motor is capable of rotating the drive shaft in an event of a failure of a second motor coupled to the drive shaft. A one-way clutch bearing, or similar device, may interface between a motor and the drive shaft to enable free rotation of the drive shaft in an event of the motor becoming inoperable, such as the motor freezing or locking in a position due to failure caused by overheating or caused by other conditions or events. Use of the second motor may secure a position of the drive shaft which may support the propeller in radial eccentric loading.

A system for determining and/or controlling motor thrust and engine thrust in a parallel hybrid aircraft. One or more sensors may be configured to monitor one or more flight parameters to generate sensor information. User input including one or more pilot estimates may be received. The sensor information may be obtained. A performance thrust ratio may be calculated based on the user input, the sensor information, an aerodynamic model, a propeller model, and a battery model. The performance thrust ratio may be used to control the motor thrust and engine thrust to improve utilization of electric energy throughout a flight. A first thrust setting for the motor and/or a second thrust setting for the engine may be determined based on the performance thrust ratio.