An aircraft propulsion system comprises a propulsor an electric motor coupled to the propulsor. The electric motor comprises a surface mounted permanent magnet electric machine comprising a rotor mounted radially inward of a stator. A Motor Diameter Ratio (MDR) is defined as an inner diameter (D.sub.stator,in) of the motor stator in metres divided by an outer diameter (D.sub.stator,out) of the motor stator in metres. The MDR of the electric motor stator is within 10% of the value given by the equation:

[00001]${\mathrm{MDR}=0.83\times (\frac{\mathrm{Torq}ue}{L_{active}}\times \frac{1}{U_{\mathrm{fan},\mathrm{tip}}})}^{0.08}$ where: T is the maximum torque rating of the electric motor in kilonewton metres; L.sub.active is the active length of the motor stator in metres; and U.sub.tip is the tip speed of the propulsor at the maximum rated torque of the electric motor in metres per second.

In the described embodiments, the MDR is less than 1.

A ducted propulsion assembly for an aircraft includes a duct and a plurality of stators. The distal ends of the stators are coupled to the duct. The ducted propulsion assembly includes a line replaceable centerbody assembly isostatically coupled to the proximal ends of the stators. The line replaceable centerbody assembly includes one or more electric motors driving an output driveshaft. The ducted propulsion assembly also includes a proprotor assembly interchangeably coupled to and rotatable with the output driveshaft of the line replaceable centerbody assembly. The proprotor assembly is rotatable in a rotational plane to generate thrust.

Disclosed is a personal flying machine using compressed air as power source, and an operation method thereof, the flying machine including a stationary rotor lift device in a cyclone duct, a seat frame and a compressed air supply device; wherein the stationary rotor lift device in a cyclone duct includes a cyclone duct, in-duct stationary rotors and in-duct compressed air artificial wind blowing ports; wherein the in-duct stationary rotor includes a stationary propeller hub and a plurality of stationary blades fixed connected around the stationary propeller hub and arranged radially; wherein the stationary blade is shaped as an airplane's wing having an airfoil, an angle of attack, a leading edge and a trailing edge; wherein the compressed-air supply device supplies compressed air to the in-duct compressed-air artificial wind blowing ports to eject airflows towards the leading edges of the stationary blades and form a cyclone to generate lift. The present application solves the problems of efficiency limitation, high cost, heavy structure and energy-environment issues related to the traditional personal flying machines of burning fossil fuels to do work, and overcomes their shortcomings and problems with the wingless or wing-movement to generate lift in relatively static air.

A ducted fan of an aircraft includes a rotor-side fan and a stator-side duct that surrounds the rotor-side fan radially at the outside and that defines a flow channel for air flowing via the fan. The stator-side duct has an inner wall facing toward the fan, an outer wall averted from the fan, and at least one stiffening strut that runs within the flow channel. The stiffening strut, at one respective end, extends through the duct and protrudes radially relative to the outer wall of the duct. At the respective end of the stiffening strut, a fastening device is formed. The fastening device is configured to mount the ducted fan on a structural component of the aircraft. The fastening device has an insert composed of a fiber-reinforced plastic and laminated into the respective end of the stiffening strut.

A convertible ducted fan engine and mounting system. The convertible ducted fan engine has a shroud encircling a mechanical fan. 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.

A propulsion system, comprising: a fan blade housing; a plurality of fan blades within the fan blade housing; one or more rows of permanent magnets, affixed to the outside of the fan blade housing; one or more fan blade bearings; one or more magnetic field generators affixed to the one or more fan blade bearings and corresponding to the one or more rows of permanent magnets, the magnetic field generators configured to cause the permanent magnets to be propelled forward in the same direction, thereby causing the fan blade housing to which they are attached, and the fan blades within, to spin.

A rotor system includes a rotor duct; at least one rotor blade that includes an outboard end; a tip extension mechanism affixed at the outboard end of the at least one rotor blade, the tip extension mechanism including at least one shim, the at least one rotor blade with the tip extension mechanism affixed thereto including an extended rotor blade; and a blade tip affixed to an outboard end of the extended rotor blade, wherein the blade tip is affixed to the extended rotor blade via at least one removable fastener.

An air mobility device improves propulsion due to the Coandă effect when flying so as to increase a flying range and reduces noise when flying.

A duct for a ducted-rotor aircraft may include an internal structure and an aerodynamic exterior skin that is adhesively bonded to the internal structure. The skin may include a leading-edge portion disposed at an inlet of the duct and an inner portion disposed along an interior of the duct. The inner portion of the skin may be bonded to the internal structure with a first bondline of adhesive and the leading-edge portion of the skin may be bonded to the inner portion of the skin with a second bondline of adhesive. One or both of the first and second bondlines of adhesive may be of non-uniform thickness to take up tolerance stackups between the inner portion of the skin, the leading-edge portion of the skin, and the internal structure.

A rotor system includes a rotor assembly and a duct system. The rotor assembly includes rotor blades extending from a mast axis and configured to rotate about the mast axis. The duct assembly includes a moveable duct portion and a stationary duct portion. In a first duct configuration, the moveable duct portion surrounds a first portion of the rotor assembly, the stationary duct portion surrounds a second portion of the rotor assembly, and the moveable duct portion and the stationary duct portion enclose the rotor assembly. In a second duct configuration, the stationary duct portion surrounds the second portion of the rotor assembly, and the moveable duct portion is moved away from the first portion of the rotor assembly, such that the rotor assembly is not enclosed.