A winglet is disclosed including first and second covers, a front spar, a rear spar, a rib, and a mid spar between the front spar and the rear spar. The rib and each spar are joined to the first cover and to the second cover. The mid spar has a length and the mid spar curves along all or part of its length. The length of the mid spar extends from an inboard end of the mid spar to an outboard end of the mid spar, and the rib wraps around the inboard or outboard end of the mid spar.

An aircraft assembly is disclosed having a wing tip device connected to a wing tip of a wing by a first connector, a second connector, and a third connector. The wing tip device includes a front device spar and a rear device spar. The first connector is associated with the rear device spar. The second connector is spaced apart in a chordwise direction forward of the first connector, and the third connector is spaced apart in a chordwise direction rearward of the first connector. The third connector includes a spigot mounting formation.

Aspects of the disclosure are directed to a system associated with an engine of an aircraft comprising: a duct, an inlet coupled to the duct, and a fence coupled to the inlet or located upstream of the inlet. In some embodiments, the system further comprises a valve body coupled to the duct. In some embodiments, the valve body includes at least one valve that is configured to rotate between a closed state and an open state.

A deployable vortex generator attached to a lifting surface includes a vane moveable relative to the lifting surface. The vane moves from a deployed position to a retracted position in response to a change in ambient conditions. In the deployed position, the vane acts on the air flow to create vortices. In the retracted position, the vane is closely aligned with the free stream velocity.

A deployable vortex generator attached to a lifting surface includes a vane moveable relative to the lifting surface. The vane moves from a deployed position to a retracted position in response to a change in ambient conditions. In the deployed position, the vane acts on the air flow to create vortices. In the retracted position, the vane is closely aligned with the free stream velocity.

A wingtip device may be attached to a baseline wing of an aircraft. The wingtip device may comprise a vertical portion coupled to the baseline wing. The vertical portion may comprise a leading edge and trailing edge. The leading edge and trailing edge may be nonlinear shapes. For example, compound curves, smooth continuous higher order polynomials, or combinations thereof. The leading edge and trailing edge may be shaped as to locate the wingtip device further aft than a conventional winglet design.

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.

A wing for an aircraft, including a main wing and a wing tip device, a front blade and a rear blade of the wing tip device extending from an attachment end, a front blade leading edge extending in front of a rear blade leading edge and a front blade trailing edge extending in front of a rear blade trailing edge, in a chord direction, and at a front blade tip the front blade extending under a different dihedral angle than the rear blade at a rear blade tip. The front blade leading and trailing edges, as well as the rear blade leading and trailing edges have a tangent-continuous developing. The front blade leading edge extends tangent-continuously with the wing leading edge. The rear blade trailing edge extends tangent-continuously with the wing trailing edge. The front blade trailing edge extends behind the rear blade leading edge, in the chord direction.

A system and method for controlling hypersonic boundary layer transition for a hypersonic flight vehicle are disclosed. The reduction or elimination of hot streaks that naturally occurs in the boundary layer transition process during hypersonic flight is achieved by utilizing various techniques. One such technique utilizes roughness elements to counteract streak development. The techniques for reducing or eliminating the streaks are tailored such that the nonlinear stages of transition are profoundly altered. This results in significant drag reduction, and consequently an increase in range of the vehicle, and also a reduction of the weight penalty due to the Thermal Protection Systems (TPS) as less protective material would be required, thus allowing for an increased payload and/or range of the vehicle.

The invention relates to a wing with at least two winglets and a respective airplane. An upstream winglet broadens a region of inclined airflow and a more downstream winglet produces a thrust contribution therein.