System And Method For Controlling A VTOL Aircraft Using Differing Blade Angle of Attack Regimes With Different Lift Coefficient Curves
OwnerGregor Veble Mikic, JoeBen Bevirtinventors
Life of this patent
Estimating the term…
Abstract
A system and method for controlling a VTOL aircraft to minimize acoustic noise. In a hover mode, the aircraft may be controlled to utilize a blade pitch angle and corresponding angle of attack range which minimizes variations in the boundary layer separation location to a point or narrow region, which reduces noise generation. The propeller blades used in the system are configured to have a reduced or no shift of the point of flow separation on the airfoil as a function of angle of attack during the hover mode. The blade design may trade off overall blade efficiency in exchange for the reduced noise during hover.
Claims19
A method of thrust control of a vertical takeoff and landing aircraft, the method comprising:
- tilting a propeller having a plurality of blades with variable pitch, the propeller being configured to tilt to a vertical orientation for hover flight mode and a horizontal orientation for forward flight mode;
- rotating the propeller to generate thrust;
- and
- controlling the variable pitch propeller to operate within different pitch regimes in the hover and forward flight modes, the pitch regime for the forward flight mode corresponding to a first angle of attack range and the pitch regime for the hover flight mode corresponding to a second angle of attack range.
A control system for the thrust control of a vertical take-off and landing aircraft, the control system comprising:
- a processor;
- and
- a memory module,
- wherein said processor is configured to control a plurality of propulsion assemblies to provide a thrust distribution around the aircraft by controlling the rotational speed and the blade pitch angle of the propulsion assemblies while maintaining the angle of attack of the blades of the propulsion assemblies within desired ranges.
A rotary airfoil blade, said blade comprising a first airfoil cross section, the first airfoil cross section defining:
- a chord line defining a chord length L;
- a leading edge, comprising a leading edge radius between 0.002 L and 0.05 L;
- a trailing edge, comprising a trailing edge thickness between zero and 0.03 L;
- a maximum thickness between 0.07 L and 0.2 L and located between 0.2 L and 0.6 L along the chord line;
- and
- a maximum camber between 0 and 0.2 L and located between 0.2 L and 0.7 L along the chord line,
- wherein said cross section has a raised feature on the top surface of the airfoil at a point 38-40% of L, with a radius of curvature of 115-119% of L, and wherein the mean camber line of the trailing edge slopes downward.
An apparatus of a vertical takeoff and landing aircraft, the apparatus comprising:
- a flight control system configured to command and control a tiltable rotor assembly by performing one of more actions, the actions comprising:
- tilting a propeller having a plurality of blades with variable pitch, the propeller being configured to tilt to a vertical orientation for hover flight mode and a horizontal orientation for forward flight mode;
- rotating the propeller to generate thrust;
- and
- controlling the variable pitch propeller to operate within different pitch regimes in the hover and forward flight modes, the pitch regime for the forward flight mode corresponding to a first angle of attack range and the pitch regime for the hover flight mode corresponding to a second angle of attack range.
Dependencies are inferred from the claim text.