SYSTEMS AND METHODS FOR PROPELLER THRUST PROTECTION

1 - 29 . (canceled)

30 . A computer-implemented method for an aircraft, comprising:

receiving, using at least one hardware processor, a descent rate command from a pilot input device;

determining, using the at least one hardware processor, a proximity of at least one propeller to a vortex ring state; and

controlling, using the at least one hardware processor, an aircraft descent rate to be less than the commanded descent rate when the at least one propeller is within a first threshold proximity to the vortex ring state.

31 . The method of claim 30 ,

wherein the proximity of the at least one propeller to the vortex ring state is determined, using the at least one hardware processor, based on an airspeed of the aircraft and at least one of: a pitch angle of the aircraft or a tilt angle of the propeller.

32 . The method of claim 31 ,

wherein the proximity of the at least one propeller to the vortex ring state is determined, using the at least one hardware processor, based on at least one of: a thrust of the propeller, a torque of the propeller, a propeller speed, or a vibration of the propeller.

33 . The method of claim 30 , wherein the proximity of the at least one propeller to the vortex ring state is determined, using the at least one hardware processor, based on an airspeed of the aircraft, a pitch angle of the aircraft, and a blade pitch of the propeller.

34 . The method of any of claim 30 , wherein the proximity of the at least one propeller to the vortex ring state is determined, using the at least one hardware processor, based on a thrust value.

35 . The method of claim 34 , wherein the thrust value is a thrust provided by the at least one propeller while the aircraft is in a hover phase.

36 . The method of claim 34 , wherein the thrust value varies based on a type of the at least one propeller.

37 . The method of claim 34 , wherein:

the at least one propeller includes at least one of a lift propeller and a tilt propeller.

38 . The method of claim 30 , wherein determining a proximity of the at least one propeller to the vortex ring state comprises determining, using the at least one hardware processor, a proximity of a state of the propeller to a multi-dimensional vortex ring state boundary.

39 . The method of claim 30 , wherein controlling the descent rate comprises:

determining, using at least one hardware processor, a maximum allowable descent rate;

inputting, using the at least one hardware processor, the maximum allowable descent rate and the descent rate command into a model which generates a descent rate command; and

controlling, using the at least one hardware processor, one or more of flight elements of the aircraft based on the generated descent rate command.

40 . The method of claim 30 , wherein controlling the descent rate comprises determining, using the at least one hardware processor, a maximum allowable descent rate based on at least one of: roll of the aircraft, pitch of the aircraft, or forward speed of the aircraft.

41 . The method of claim 30 , further comprising:

providing, using the at least one hardware processor, a warning to the pilot based on the at least one propeller being within a second threshold proximity to the vortex ring state;

wherein the second threshold proximity is different from the first threshold proximity; and

wherein the warning includes at least one of: a displaying of text, a turning on of a light, a changing of a light color, an audible notification, or a haptic notification.

42 . The method of claim 41 , wherein the second threshold proximity is further from the vortex ring state than the first threshold proximity.

43 . The method of claim 30 , further comprising controlling at least one of: propeller tilt angle, aircraft roll angle, aircraft pitch angle, or propeller speed based on the at least one propeller being within the threshold proximity to the vortex ring state.

44 . The method of claim 30 , further comprising detecting, using the at least one hardware processor, an airspeed of the aircraft, wherein the determining the proximity of the at least one propeller to the vortex ring state is performed upon determining, using the at least one hardware processor, the airspeed is below a threshold speed.

45 . The method of claim 30 , further comprising detecting, using the at least one hardware processor, an airspeed of the aircraft, wherein the controlling the aircraft's descent rate to be less than the commanded descent rate is performed upon determining, using the at least one hardware processor, the detected airspeed is less than a threshold.

46 . The method of claim 30 , further comprising detecting, using the at least one hardware processor, whether the aircraft is receiving powered lift support, wherein the determining the proximity of the at least one propeller to the vortex ring state is performed, using the at least one hardware processor, upon detecting the aircraft is receiving powered lift support.

47 . The method of claim 30 , wherein controlling the descent rate comprises controlling, using the at least one hardware processor, the aircraft based on a determined maximum allowable descent rate.

48 . The method of claim 47 , further comprising detecting, using the at least one hardware processor, a vibration of the at least one propeller, wherein the maximum allowable descent rate is reduced based on the detected vibration exceeding a threshold vibration.

49 . The method of claim 30 , wherein the pilot input device is at least one inceptor device.

50 . The method of claim 30 , further comprising:

determining, using the at least one hardware processor, the at least one propeller has entered a vortex ring state; and

controlling, using the at least one hardware processor, tilt angle of the at least one propeller based on the determination.

51 . The method of claim 30 , further comprising:

receiving, using the at least one hardware processor, an aircraft maneuver rate command from the pilot input device;

determining, using the at least one hardware processor, a proximity of the at least one propeller to a vortex ring state; and

controlling, using the at least one hardware processor, an aircraft maneuver rate to be less than the commanded maneuver rate based on the at least one propeller being within a threshold proximity to the vortex ring state; and

wherein the maneuver rate is at least one of: yaw rate, roll rate, or pitch rate.

52 . The method of claim 30 , further comprising determining, using the at least one hardware processor, a proximity of a propeller blade of the at least one propeller to the vortex ring state.

53 . The method of claim 30 , further comprising calculating, using the at least one hardware processor, an induced velocity produced by the at least one propeller, wherein the determining the proximity of the at least one propeller to the vortex ring state is based on the induced velocity.

54 . The method of claim 53 , wherein further comprising calculating, using the at least one hardware processor, the induced velocity produced by the at least one propeller based on one or more of an air density, an area of the at least one propeller, and a thrust.

55 . A control system comprising at least one processor configured to execute instructions to cause the system to perform operations comprising:

receiving a descent rate command from a pilot input device;

determining a proximity of at least one propeller to a vortex ring state; and

controlling an aircraft descent rate to be less than the commanded descent rate when the at least one propeller is within a first threshold proximity to the vortex ring state.

56 . A computer-implemented method for an aircraft, comprising:

receiving, using at least one hardware processor, a descent rate command from a pilot input device;

determining, using the at least one hardware processor, a proximity of at least one propeller to a vortex ring state; and

providing, using the at least one hardware processor, a warning to the pilot based on the at least one propeller being within a first threshold proximity to the vortex ring state.

57 . The method of claim 56 , wherein the warning includes at least one of: a displaying of text, a turning on of a light, a changing of a light color, an audible notification, or a haptic notification.

58 . The method of claim 56 , further comprising:

controlling, using the at least one hardware processor, an aircraft descent rate to be less than the commanded descent rate when the at least one propeller is within a second threshold proximity to the vortex ring state;

wherein the second threshold proximity is different from the first threshold proximity, and wherein the second threshold proximity is further from the vortex ring state than the first threshold proximity.

59 . A control system comprising at least one processor configured to execute instructions to cause the system to perform operations comprising:

receiving a descent rate command from a pilot input device;

determining a proximity of at least one propeller to a vortex ring state; and

providing a warning to the pilot based on the at least one propeller being within a first threshold proximity to the vortex ring state.