Multi-rotor rotorcraft comprise a fuselage, and at least four rotor assemblies operatively supported by and spaced-around the fuselage. Each of the at least four rotor assemblies defines a spin volume and a spin diameter. Some multi-rotor rotorcraft further comprise at least one rotor guard that is fixed relative to the fuselage, that borders the spin volume of at least one of the at least four rotor assemblies, and that is configured to provide a visual indication of the spin volume of the at least one of the at least four rotor assemblies. Various configurations of rotor guards are disclosed.

An aircraft includes a wing having an integrated ducted fan. The ducted fan is optionally equipped with inlet louvers and outlet louvers. The inlet louvers and the outlet louvers are adjustable between an open position and a closed position.

An intentional fluid manipulation apparatus (IFMA) assembly with a first thrust apparatus that imparts a first induced velocity to a local free stream flow during a nominal operation requirement. The first thrust apparatus creates a streamtube. A second thrust apparatus is located in a downstream portion of the streamtube. The second thrust apparatus imparts a second induced velocity to the local free stream flow. The second induced velocity at the location of the second thrust apparatus has a component in a direction opposite to the direction of the first induced velocity at the location of the second thrust apparatus.

A proprotor system for a ducted aircraft convertible between a vertical takeoff and landing flight mode and a forward flight mode includes a plurality of proprotor blades and a duct surrounding the proprotor blades. The duct includes an adaptive geometry device movable into various positions including a hover position and a cruise position. One or more actuators coupled to the adaptive geometry device are configured to move the adaptive geometry device between the hover position and the cruise position based on the flight mode of the ducted aircraft, thereby improving flight performance of the ducted aircraft.

An arrowhead aircraft includes a pair of counter-rotating propellers, a jet engine module, and an exhausted module, wherein the counter-rotating propellers propel the aircraft but does not have angular momentum, and the exhausted module deployed around the exhausted end of the jet engine module, which reuses the waste heat from the exhausted end and reduces the noise. Wherein, the airflow system includes a shutter deployed at the bottom side of the body that controls the streamlines of airflow through the aircraft and a plurality of airfoils that will force the aircraft tilted to the desired direction. The present invention resolved the helicopter's vulnerabilities, such as its intricate mechanism, dragging response, dangers blades, hard to control angular momentum, high cost, and high training level.

This disclosure describes a configuration of an aerial vehicle, such as an unmanned aerial vehicle, in which one or more of the propellers are positioned within a duct that includes an active airflow channel within the interior of the duct. The active airflow channel actively moves within the duct so that it remains aligned with the tips of the blades of the propeller within the duct. As the propeller and the active airflow channel rotate, at least some of the airflow structures (e.g., vortices) shed from the blades of the propeller are collected by the active airflow channel and channeled away from the propeller so that a following blade of the propeller does not pass through the collected airflow structures.

A diverter duct for a propeller includes a second duct element having a semi-annular wedge shape, which is pivotably coupled to the first duct element, a first drive structure configured to drive a pivoting of the second duct element relative to the first duct element and a second drive structure configured to drive a rotation of the first and second duct elements about an axis of rotation of the propeller.

A vehicle includes a propulsion system using one or more impellers as opposed to propellers. The impellers impart circumferential and radial velocity components to the working fluid, which may be air or water. The air is deflected by counter-vortex chambers in a shroud to convert the circumferential and radial velocity to an axial velocity aligned with the axis of rotation of the impeller.

An autonomous thrust vectoring ring wing pod is disclosed. A plurality of distributed propulsion element (thruster) layout within a self-articulating ring wing pod allows the pod to selectively control its thrust vector by controlling each propulsion element in the pod. This arrangement allows autonomous and independent control of the tilting of the ring wing relative to the aircraft. The ring wing pod acts as both a nacelle to house the propulsion elements as well as a lifting surface when in wing-borne flight. The autonomous thrust vectoring ring wing pod also provides superior aircraft attitude control in wing-borne flight, thus negating the need for conventional surface controls.

A fuel efficient aircraft propulsion system comprises a wingtip mounted ducted pusher fan with convergent backwash and a skewed conical engine nacelle. The system both mitigates wingtip vortex drag and converts a portion of vortex energy into propulsion force and lift force. The forward-tapering nacelle skews both downward and inward, so the lower nacelle surface is flush with the lower wing surface and the inboard nacelle surface does not alter flow over the upper wing surface. This firstly preserves lift at the outboard wing end. Secondly, air displacement by the nacelle accelerates flow only on the outboard and upper nacelle surfaces, and because the nacelle occupies the core of the nascent wingtip vortex, rotational air velocity is greatest on the upper nacelle surface. The resultant pressure drop on the upper nacelle surface contributes to aircraft lift. And because the nacelle surface tapers forward, this pressure drop does not exert backward-acting drag on the aircraft. Aft of the nacelle, the pusher fan hub surface conforms with the aft nacelle surface and tapers aft. Propulsion foils project from the forward portion of the pusher fan hub at an outward-aft angle, which directs convergent high pressure backwash flow along the aft tapering hub surface. This isolates aft-facing hub surfaces from drag-inducing vortex core pressure drop. Downstream fan backwash convergence then forms a central volume of high pressure flow where the low pressure trailing vortex core would otherwise develop. This is an efficient means to dissipate the cyclonic structure of the vortex, because vortex persistence requires low pressure core persistence. The direction of pusher fan rotation opposes the direction of wingtip vortex rotation as described in the prior art. This cross-flow interaction increases the effective power of the fan and also further counters vortex formation. An integral peripheral duct links the outer ends of the fan propulsion foils to provide thrust efficiency similar to that of a high bypass fanjet engine, but without the internal air friction within a bypass channel. In an alternative horizontal axis wind turbine embodiment, the same nacelle form supports secondary power-takeoff turbines mounted in high energy density flow at the turbine blade tips.