A turboelectric distributed propulsion based on brushless doubly-fed machines (BDFMs) is provided, which minimizes power conversion, enhances mechanical reliability, and strengthens fault-tolerance capability of a DC-based propulsion system. A turboelectric distributed propulsion (TeDP) architecture using BDFMs for aviation applications, and a designed BDFM, inverter, and controller are provided. Simulations and systems are also provided.

A clutch that has a synchronizer for matching a rotational velocity of a drive input with a rotational velocity of a driven output prior to engagement of a locking mechanism.

A clutch that has a synchronizer for matching a rotational velocity of a drive input with a rotational velocity of a driven output prior to engagement of a locking mechanism.

A hybrid electric aircraft propulsion system and method of operation are described. The system comprises a thermal engine, a generator coupled to the thermal engine, a first electric propulsor operatively connected to the generator to receive alternating current (AC) electric power therefrom, a second electric propulsor, a generator inverter operatively connected to the generator to convert AC electric power to direct current (DC) electric power, and a first motor inverter operatively connected to the generator inverter and selectively connected to one of the first electric propulsor and the second electric propulsor and configured to receive the DC electric power and provide the first electric propulsor and the second electric propulsor with AC electric power, respectively.

A hybrid electric aircraft propulsion system and method of operation are described. The system comprises a thermal engine, a generator coupled to the thermal engine, a first electric propulsor operatively connected to the generator to receive alternating current (AC) electric power therefrom, a second electric propulsor, a generator inverter operatively connected to the generator to convert AC electric power to direct current (DC) electric power, and a first motor inverter operatively connected to the generator inverter and selectively connected to one of the first electric propulsor and the second electric propulsor and configured to receive the DC electric power and provide the first electric propulsor and the second electric propulsor with AC electric power, respectively.

A clutch has an inner race, an outer race spaced from the inner race and forming a radial cavity between the races, and a plurality of sprags disposed in the radial cavity. The sprags have a different coefficient of thermal expansion (CTE) from the inner race, the outer race, or both races, and a sprag cage retains the sprags at a uniform spacing within the radial cavity. When the clutch is at a first temperature, a gap exists between the sprags and the inner race, between the sprags and the outer race, or between the sprags and both races, and the clutch is disengaged. When the clutch is at a second temperature the sprags are in contact with both the races, and the clutch is engaged.

A clutch has an inner race, an outer race spaced from the inner race and forming a radial cavity between the races, and a plurality of sprags disposed in the radial cavity. The sprags have a different coefficient of thermal expansion (CTE) from the inner race, the outer race, or both races, and a sprag cage retains the sprags at a uniform spacing within the radial cavity. When the clutch is at a first temperature, a gap exists between the sprags and the inner race, between the sprags and the outer race, or between the sprags and both races, and the clutch is disengaged. When the clutch is at a second temperature the sprags are in contact with both the races, and the clutch is engaged.

A convertible ducted fan engine having a shroud, a drive shaft connected to a mechanical fan, and a rotational drive motor configured to rotate the mechanical fan. An embodiment includes a linear drive motor configured to translate the drive shaft and mechanical fan in a direction parallel to a longitudinal axis of the shroud. The convertible ducted fan engine includes a fluid-propulsion configuration in which the mechanical fan rotates freely with respect to the shroud to produce thrust through fluid flow, and a drive-wheel configuration in which the shroud rotates about the rotational axis.

In an aspect, a system comprising a computing device. The computing device is configured to determine a drag minimization axis of a rotor connected to an aircraft. The rotor includes a first end and a second end. The rotor is configured to rotate about an axis. The computing device is further configured to determine a halting point of the rotor, wherein the halting point includes a drag minimization axis of the rotor. The computing device is configured to send a halting command to at least a magnetic element to halt the rotor, wherein the halting process is configured to stop a movement of the rotor and position the rotor in the halting point. The position of the rotor in the halting point includes the first end pointing in one direction of the drag minimization axis and the second end pointing in an opposite direction of the first end.

In an aspect, a system comprising a computing device. The computing device is configured to determine a drag minimization axis of a rotor connected to an aircraft. The rotor includes a first end and a second end. The rotor is configured to rotate about an axis. The computing device is further configured to determine a halting point of the rotor, wherein the halting point includes a drag minimization axis of the rotor. The computing device is configured to send a halting command to at least a magnetic element to halt the rotor, wherein the halting process is configured to stop a movement of the rotor and position the rotor in the halting point. The position of the rotor in the halting point includes the first end pointing in one direction of the drag minimization axis and the second end pointing in an opposite direction of the first end.