The invention discloses a propeller-driven helicopter or airplane which comprises a fuselage and a propeller comprising a plurality of blades, wherein a plurality of pressure pipes are uniformly distributed between windward sides and leeward sides of the blades; a plurality of first inlets are formed in the windward sides and are communicated with outside via first channels in the blades and second outlets at tails of the blades; a high-pressure fluid of a low-speed fluid layer formed when a fluid flows through the leeward sides in a widthwise direction flows towards a low-pressure fluid of a high-speed fluid layer formed when the fluid flows through the first inlets, the first channels and the second outlets; and an upward pressure generated by the high-pressure fluid is opposite to a downward pressure generated by an external fluid above the windward sides, so that a fluid pressure above the propeller is decreased.

The invention discloses a propeller-driven helicopter or airplane which comprises a fuselage and a propeller comprising a plurality of blades, wherein a plurality of pressure pipes are uniformly distributed between windward sides and leeward sides of the blades; a plurality of first inlets are formed in the windward sides and are communicated with outside via first channels in the blades and second outlets at tails of the blades; a high-pressure fluid of a low-speed fluid layer formed when a fluid flows through the leeward sides in a widthwise direction flows towards a low-pressure fluid of a high-speed fluid layer formed when the fluid flows through the first inlets, the first channels and the second outlets; and an upward pressure generated by the high-pressure fluid is opposite to a downward pressure generated by an external fluid above the windward sides, so that a fluid pressure above the propeller is decreased.

A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.

A propeller includes a blade free to rotate. A first stop is positioned to mechanically engage one or both of a first portion of the blade and a first structure coupled to the blade when the blade is in a first position at a first end of the rotational range of motion. A second stop is positioned to mechanically engage one or both of a second portion of the blade and a second structure coupled to the blade when the blade is in a second position at a second end of the defined rotational range. The blade rotates to the first position against the first stop when the propeller is rotated in a first direction and to the second position against the second stop when the propeller is rotated in a second direction.

A blade in which the aerodynamic profiles of a blade root, a blade neck and a central part of a profiled zone of the blade respectively comprise a leading edge section and a trailing edge section that are symmetrical to each other relative to an axis of symmetry. The present disclosure also concerns a method for constructing such a blade. The axis of symmetry is perpendicular to a segment connecting the leading edge to the trailing edge of each profile and is positioned in the middle of the segment. An intermediate upper surface section and an intermediate lower surface section connect the leading edge section and the trailing edge section in order to respectively form a lower surface of the aerodynamic profile.

A blade in which the aerodynamic profiles of a blade root, a blade neck and a central part of a profiled zone of the blade respectively comprise a leading edge section and a trailing edge section that are symmetrical to each other relative to an axis of symmetry. The present disclosure also concerns a method for constructing such a blade. The axis of symmetry is perpendicular to a segment connecting the leading edge to the trailing edge of each profile and is positioned in the middle of the segment. An intermediate upper surface section and an intermediate lower surface section connect the leading edge section and the trailing edge section in order to respectively form a lower surface of the aerodynamic profile.

A replacement tip section for a rotor blade, from which a legacy tip section was removed, includes a blade tip portion configured to be attached to an intermediate section of the rotor blade after removal of the legacy section. The intermediate section has a connection feature at an end of the intermediate section to which the blade tip portion is attachable. The replacement tip section includes a transition region configured to be attached to a forward end of the connection feature. The transition region is configured to form a leading edge of the rotor blade and extends from the blade tip portion to form an opening into which the intermediate section is attached. The transition region includes a first end having a first airfoil that conforms to the intermediate section airfoil at the connection feature, and a second end having a second airfoil that conforms to the blade tip portion.

A replacement tip section for a rotor blade, from which a legacy tip section was removed, includes a blade tip portion configured to be attached to an intermediate section of the rotor blade after removal of the legacy section. The intermediate section has a connection feature at an end of the intermediate section to which the blade tip portion is attachable. The replacement tip section includes a transition region configured to be attached to a forward end of the connection feature. The transition region is configured to form a leading edge of the rotor blade and extends from the blade tip portion to form an opening into which the intermediate section is attached. The transition region includes a first end having a first airfoil that conforms to the intermediate section airfoil at the connection feature, and a second end having a second airfoil that conforms to the blade tip portion.

A method and system for generating a set of values for respective ones of a set of parameters used in determining rotor blade profiles for a corotating coaxial rotor system. The method comprises establishing a ratio of respective desired thrusts of an upper rotor and a lower rotor of the corotating coaxial rotor system based on a desired performance of the corotating coaxial rotor system; and determining the set of values of the set of parameters from the desired thrusts ratio based on an equal rotation speed condition between the upper rotor and the lower rotor of the corotating coaxial rotor system, wherein the set of parameters includes torques of the upper rotor and the lower rotor.

A method and system for generating a set of values for respective ones of a set of parameters used in determining rotor blade profiles for a corotating coaxial rotor system. The method comprises establishing a ratio of respective desired thrusts of an upper rotor and a lower rotor of the corotating coaxial rotor system based on a desired performance of the corotating coaxial rotor system; and determining the set of values of the set of parameters from the desired thrusts ratio based on an equal rotation speed condition between the upper rotor and the lower rotor of the corotating coaxial rotor system, wherein the set of parameters includes torques of the upper rotor and the lower rotor.