A proprotor blade for a ducted aircraft including a duct includes a main body having a distal end and a sacrificial blade tip coupled to the distal end of the main body. The sacrificial blade tip includes a deformable core material and a shell layer at least partially covering the deformable core material. The sacrificial blade tip deforms upon contact with the duct, thereby reducing damage to the ducted aircraft.

A tip gap monitoring system for a ducted aircraft having a proprotor system including a duct and a plurality of proprotor blades includes sensors coupled to the proprotor system. The sensors are configured to detect one or more parameters of the proprotor system to form a plurality of sensor measurements. The tip gap monitoring system also includes a flight control computer in data communication with the sensors. The flight control computer includes a tip gap measurement module configured to determine a tip gap distance between the duct and the proprotor blades based on the sensor measurements.

A tip gap control system for a ducted aircraft includes a flight control computer including an inner duct surface control module configured to generate an inner duct surface actuator command and a proprotor system in data communication with the flight control computer. The proprotor system includes a duct having active inner duct surfaces movable into various positions including a retracted position and an extended position. The proprotor system also includes proprotor blades surrounded by the duct and one or more actuators coupled to the active inner duct surfaces. The one or more actuators move the active inner duct surfaces between the various positions based on the inner duct surface actuator command, thereby controlling a tip gap between the proprotor blades and the duct.

A tip gap control system for a ducted aircraft includes a flight control computer including a blade length control module configured to generate a blade tip actuator command and a proprotor system in data communication with the flight control computer. The proprotor system includes a duct and proprotor blades surrounded by the duct. Each of the proprotor blades includes an active blade tip movable into various positions including a retracted position and an extended position. The tip gap control system also includes one or more actuators coupled to the active blade tips. The one or more actuators move the active blade tips between the various positions based on the blade tip actuator command, thereby controlling a tip gap between the proprotor blades and the duct.

One embodiment is a rotor system comprising a duct ring; a hub disposed centrally to the duct ring; first and second stators each connected between the duct ring and the hub; first and second control vanes rotatably connected to the first and second stators, respectively; and a structural hoop having a first end connected to the first control vane and a second end connected to the second control vane, the structural hoop for translating rotation of the first control vane about a vane axis to the second control vane.

One embodiment is a rotor system comprising a duct ring; a hub disposed centrally to the duct ring; first and second stators each connected between the duct ring and the hub; first and second control vanes rotatably connected to the first and second stators, respectively; and a structural hoop having a first end connected to the first control vane and a second end connected to the second control vane, the structural hoop for translating rotation of the first control vane about a vane axis to the second control vane.

A proprotor system for a ducted aircraft includes a duct and proprotor blades surrounded by the duct. Each proprotor blade is rotatable about a respective pitch change axis. The proprotor blades are configured to change collective pitch about the pitch change axes. The proprotor blades are extendable along the pitch change axes into various positions including a retracted position and an extended position. The proprotor blades change between the retracted position and the extended position based on the collective pitch of the proprotor blades, thereby controlling a tip gap between the proprotor blades and the duct.

A cycloidal rotor is provided having a flexible by actuators or self-flexing blade-positioning tack, which can be brought into shape corresponding to currently desired blade orbit. This rotor can also be provided with frontal shielding or partial enclosure to assure that rotor operates at any speed as if in hovering flight; rotor track can be inclined to produce forward thrust or external thrusters can be used. Optionally in other embodiments blade orbit shape is determined by a variable cam mechanism or the inclination of blade positioning track of fixed shape to produce a change of its projected shape onto blades' plane of operation thus changing blades elliptic orbit. Blade centrifugal force countervailing mechanism is also proposed.

A cycloidal rotor is provided having a flexible by actuators or self-flexing blade-positioning tack, which can be brought into shape corresponding to currently desired blade orbit. This rotor can also be provided with frontal shielding or partial enclosure to assure that rotor operates at any speed as if in hovering flight; rotor track can be inclined to produce forward thrust or external thrusters can be used. Optionally in other embodiments blade orbit shape is determined by a variable cam mechanism or the inclination of blade positioning track of fixed shape to produce a change of its projected shape onto blades' plane of operation thus changing blades elliptic orbit. Blade centrifugal force countervailing mechanism is also proposed.

A tip gap control system for a ducted aircraft includes a flight control computer including a blade length control module configured to generate a blade tip actuator command and a proprotor system in data communication with the flight control computer. The proprotor system includes a duct and proprotor blades surrounded by the duct. Each of the proprotor blades includes an active blade tip movable into various positions including a retracted position and an extended position. The tip gap control system also includes one or more actuators coupled to the active blade tips. The one or more actuators move the active blade tips between the various positions based on the blade tip actuator command, thereby controlling a tip gap between the proprotor blades and the duct.