An aerial vehicle includes an aerial vehicle body, and first and second rotor assemblies. The first rotor assembly includes a first hub coupled to first blades, and a first drive shaft coupled to the first hub via fastening features. The first drive shaft is configured to rotate the first hub in a first direction such that the first blades rotate in a first rotation plane. The second rotor assembly includes a second hub coupled to second blades, and a second drive shaft coupled to the second hub via fastening features. The second drive shaft is configured to rotate the second hub in a second direction opposite to the first direction, such that the second blades rotate in a second rotation plane. The first and second rotation planes are at opposite sides of the aerial vehicle body.

A ram air turbine (RAT) can include a housing and a turbine shaft configured to connect to one or more turbine blades and be turned by the one or more blades. The turbine shaft can be disposed in the housing to rotate relative to the housing along a rotational axis. The RAT can include a first bearing and a second bearing mounted between the turbine shaft and the housing to allow the turbine shaft to rotate relative to the housing. The RAT can include a whirl reduction system configured to dampen or eliminate whirl around the rotational axis.

A rotor blade tip clearance control method and a rotor blade manufactured using same. The control method includes: coinciding, along an axial direction of an aircraft engine, center of gravity of a rotor blade with center of gravity of a rotor wheel disk supporting the rotor blade; rotating the rotor wheel disk to measure a leading edge deformation amount of the rotor blade; measuring a trailing edge deformation amount of the rotor blade; comparing the deformation amounts; and adjusting the center of gravity of the rotor wheel disk until the leading edge deformation amount tends to be approximately equal to the trailing edge deformation amount. The method can effectively improve or even solve the problem of inconsistent radial displacements of a leading edge and a trailing edge during the operation.

A variable pitch propeller assembly operatively coupled with an engine and methods for controlling the pitch of a plurality of propeller blades thereof is provided. In one example aspect, the variable pitch propeller assembly includes features for combining overspeed, feathering, and reverse functionality in a single secondary control valve. The secondary control valve is operable to selectively allow a controlled amount of hydraulic fluid to flow to or from a pitch actuation assembly such that the pitch of the propeller blades can be adjusted to operate the variable pitch propeller assembly in one of a constant speed mode, a feather mode, and a reverse mode.

To provide an axial flow turbine that can reduce interference loss and secondary flow loss, and can reduce mixing loss. An axial flow turbine includes: stator blades provided on the inner-circumference side of a diaphragm outer ring; a diaphragm inner ring provided on the inner-circumference side of the stator blades; moving blades provided on the outer-circumference side of a rotor; a shroud provided on the outer-circumference side of the moving blades; a main flow path constituted by a flow path formed between an inner circumferential surface of the diaphragm outer ring and an outer circumferential surface of the diaphragm inner ring, and a flow path formed between an inner circumferential surface of the shroud and an outer circumferential surface of the rotor; and a cavity formed between the diaphragm inner ring and the rotor. The outer circumferential surface of the rotor has protruding portions and depressed portions. Each depressed portion extends along a relative flow direction of a working fluid passed through the stator blades in the main flow path.

Systems, methods, and devices for propelling self-propelled movable objects are provided. In one aspect, a rotor assembly for a self-propelled movable object comprises: a hub comprising a first fastening feature; a drive shaft comprising a second fastening feature and directly coupled to the hub by a mating connection of the first and second fastening features, wherein the drive shaft is configured to cause rotation of the hub such that the mating connection of the first and second fastening features is tightened by the rotation; and a plurality of rotor blades coupled to the hub and configured to rotate therewith to generate a propulsive force.

A fan exit guide vane assembly for a gas turbine engine includes a plurality of guide vanes having a pressure side and a suction side extending between a leading edge and a trailing edge. The vanes further include a span extending between a root and tip with a stagger angle defined as an angle between a longitudinal axis parallel to an engine axis of rotation and a line connecting the leading edge and the trailing edge that is less than about 15.

A blade containment system includes a plurality of circumferentially-arranged rotatable blades. Each blade has a blade compliance. An annular containment structure is arranged around the rotatable blades. The containment structure includes a liner that has a liner compliance. The blade compliance and the liner compliance are configured such that a strain induced on a respective one of the blades upon impact with the liner is less than a threshold critical strain beyond which the rotatable blades fracture.

A bladed disc for a turbine engine has disc and blade portions. The disc portion extends in a radial direction from the turbine engine central axis and has slots around its circumference with an inverse fir tree profile. The blade portion has aerofoil and root sections. The root section is configured to have a fir tree profile. The blade portion engages with a slot on the disc portion circumference with the fir tree profile of the root section of the blade portion engaging with the inverse fir tree profile of the slot within the disc portion. The fir tree profile of the root section of the blade portion and the inverse fir tree profile of the slot of the disc portion are curved. The bladed disc has a clearance plate mounted on at least one of the blades, the clearance plate extending across the slot on the disc portion.

A pneumatic motor for pneumatic tools includes a cylinder provided therein with a vane wheel. A rotating shaft inserted in the vane wheel is provided with a withstanding member and a tightening member, which can push the withstanding member to move toward the vane wheel and tighten the vane wheel with the rotating shaft for avoiding gap between the vane wheel and the rotating shaft. Thus, when outside driving air pushes the vane wheel to rotate, the vane wheel can synchronously drive the rotating shaft to rotate immediately and truly. By so designing, this invention can solve the problems of the conventional pneumatic motor that is likely to cause starting delay, untrue in power transmission and easy to wear.