Various embodiments of an airfoil and machines with airfoils are disclosed. The airfoils include a thicker leading airfoil portion and a thinner trailing airfoil portion. In one embodiment, the leading airfoil portion is formed by bending a body of the airfoil back toward itself. In another embodiment, the leading airfoil portion has a solid geometry and includes two elliptic surfaces. To prevent detachment of airflow, the leading airfoil portion includes at least two arc portions or surfaces that act to direct the airflow down to the trailing airfoil portion in a manner that stabilizes vortexes that may form in the region of changing thickness.

Various embodiments of an airfoil and machines with airfoils are disclosed. The airfoils include a thicker leading airfoil portion and a thinner trailing airfoil portion. In one embodiment, the leading airfoil portion is formed by bending a body of the airfoil back toward itself. In another embodiment, the leading airfoil portion has a solid geometry and includes two elliptic surfaces. To prevent detachment of airflow, the leading airfoil portion includes at least two arc portions or surfaces that act to direct the airflow down to the trailing airfoil portion in a manner that stabilizes vortexes that may form in the region of changing thickness.

A method of improving a blade and also an improved blade and a advancement propeller including the improved blade. The radius of the initial leading edge circle of each airfoil of the blade is increased, and its leading edge is moved away from a pressure side half-airfoil towards a suction side half-airfoil, thereby modifying the airfoil of each cross-section of the blade and modifying the camber of each airfoil. Consequently, the absolute value of the negative stall angle of attack of the blade is increased, thus making it possible to increase the aerodynamic performance of the blade under a negative angle of attack compared with a blade that is not modified, and without significantly degrading its aerodynamic performance under a positive angle of attack.

This invention provides convenient airframe vibration, tracking, and acoustic improvements of a helicopter rotor blade by use of a profile system. The profile system is designed to minimize acoustic disturbances as air passes the airfoil. The profile may be attached through an adhesive system that allows convenient removal and relocation for use by the helicopter manufacturer or by the helicopter operator in a field environment.

This invention provides convenient airframe vibration, tracking, and acoustic improvements of a helicopter rotor blade by use of a profile system. The profile system is designed to minimize acoustic disturbances as air passes the airfoil. The profile may be attached through an adhesive system that allows convenient removal and relocation for use by the helicopter manufacturer or by the helicopter operator in a field environment.

A main rotor blade 1, which is the main rotor blade 1 for a high-velocity helicopter, includes: a blade root part 10 having a length of 30% or more of a rotor radius R; and a blade main body 20 continuous with the blade root part 10. Preferably, a cross-sectional shape of the blade root part 10 satisfies (x/a).sup.m+(y/b).sup.m=1 and a>b, where m: arbitrary number, x: chord length direction, and y: blade thickness direction.

A main rotor blade 1, which is the main rotor blade 1 for a high-velocity helicopter, includes: a blade root part 10 having a length of 30% or more of a rotor radius R; and a blade main body 20 continuous with the blade root part 10. Preferably, a cross-sectional shape of the blade root part 10 satisfies (x/a).sup.m+(y/b).sup.m=1 and a>b, where m: arbitrary number, x: chord length direction, and y: blade thickness direction.

A rotor blade assembly for a rotary wing aircraft includes a main rotor blade body comprising an upper blade skin, a lower blade skin, an inboard end, an outboard end, and a trailing edge. The rotor blade assembly further includes a trailing edge actuator assembly. The trailing edge actuator assembly includes an upper actuator skin and a lower actuator skin defining a cavity and a trailing edge flap, a control panel disposed in the cavity and coupled to one of the upper actuator skin or the lower actuator skin and one or more actuators disposed in the cavity and configured to apply force to the control panel to cause the trailing edge flap to deflect. The trailing edge actuator assembly is coupled to the trailing edge of the main rotor blade body.

A rotor blade assembly for a rotary wing aircraft includes a main rotor blade body comprising an upper blade skin, a lower blade skin, an inboard end, an outboard end, and a trailing edge. The rotor blade assembly further includes a trailing edge actuator assembly. The trailing edge actuator assembly includes an upper actuator skin and a lower actuator skin defining a cavity and a trailing edge flap, a control panel disposed in the cavity and coupled to one of the upper actuator skin or the lower actuator skin and one or more actuators disposed in the cavity and configured to apply force to the control panel to cause the trailing edge flap to deflect. The trailing edge actuator assembly is coupled to the trailing edge of the main rotor blade body.

A rotary wing aircraft includes a single main rotor hub configured to receive a rotor blade. The rotor blade includes a blade root, a blade tip, and a blade body. The blade body includes a leading edge and a trailing edge and defines a feathering axis. The leading edge and the trailing edge each include a first portion and a second portion that extend toward a first direction and a second portion, respectively. At a given radial location along the feathering axis, a local twist angle changes from a positive value to a negative value, a chord length decreases in value, a distance between the trailing edge and the feathering axis decreases in value, and the first portion of the leading edge extends toward the first direction. The rotor blade assembly also includes a trailing edge assembly having a trailing edge flap configured to be selectively deployed by an actuator.