Aircraft having foldable wings

Aircrafts having foldable wings are disclosed. An example aircraft includes a fixed wing portion, a foldable wing tip, and a hinge interface to pivotally couple the foldable wing tip and the fixed wing portion. The hinge interface has a first hinge defining a hinge axis that is substantially parallel to a fuselage centerline. The first hinge has a first dimension in a spanwise direction and a second dimension in a chordwise direction. The first dimension is greater than the second dimension.

FIELD

The present disclosure relates generally to aircraft and, more particularly, to aircraft having foldable wings.

BACKGROUND

Long span wings are desirable for commercial aircraft because such wings are more aerodynamically efficient relative to wings having a shorter span. Greater aerodynamic efficiency reduces fuel consumption, which reduces operating costs. However, the wingspan of an aircraft can be constrained based on dimensional limits and/or regulations imposed by the International Civil Aviation Organization (ICAO), and/or based on physical infrastructure limitations of airports (e.g., the relative sizes of runways, taxiways, gate areas, hangars, etc.).

SUMMARY

An example aircraft includes a fixed wing portion, a foldable wing tip, and a hinge interface to pivotally couple the foldable wing tip and the fixed wing portion. The hinge interface has a first hinge defining a hinge axis that is substantially parallel to a fuselage centerline. The first hinge has a first dimension in a spanwise direction and a second dimension in a chordwise direction. The first dimension is greater than the second dimension.

Another example aircraft includes a wing having a fixed wing portion and a foldable wing tip. A hinge interface pivotally couples the foldable wing portion to the fixed wing portion. The hinge interface includes a first wing rib and a second wing rib spaced from the first wing rib to define a first hinge. The first wing rib supports a first hinge pin and the second wing rib to support a second hinge pin. Each of the first wing rib and the second wing rib has a longitudinal axis to extend between the foldable wing tip and the fixed wing portion in a direction substantially perpendicular to a fuselage centerline of the aircraft.

Another example aircraft includes a first wing having a first fixed portion and a first foldable portion and a second wing having a second fixed portion and a second foldable portion. The first wing and the second wing provide a first wingspan when the first foldable portion and the second foldable portion are in extended positions. The first wing and the second wing provide a second wingspan when the first foldable portion and the second foldable portion are in a folded position. The first wingspan is greater than approximately 65 meters and the second wingspan is less than approximately 65 meters, and where each of the first and second foldable portions rotate about a hinge axis that is substantially parallel relative to a fuselage centerline.

Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts. As used in this disclosure, stating that any part (e.g., a layer, film, area, or plate) is in any way positioned on (e.g., positioned on, located on, disposed on, or formed on, etc.) another part, means that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween. Stating that any part is in contact with another part means that there is no intermediate part between the two parts.

DESCRIPTION

Wings having a longer, thinner profile are more aerodynamically efficient than shorter, thicker wings. Likewise, higher aspect ratio wings produce more efficient flight than lower aspect ratio wings. Aircraft wings, for example, may be designed to reduce drag by manipulating an aspect ratio of the wings. The aspect ratio of the aircraft wings is the ratio of the span of the wings to the mean chord of the wings. The span is the distance from one wingtip to the other wingtip. The span is measured in a straight line from wingtip to wingtip, independently of wing shape or sweep. A chord is a reference straight line joining a leading edge and a trailing edge of the aircraft wing. A chord length is a distance between the trailing edge and the point on the leading edge where the chord intersects the leading edge. Most aircraft wings are not rectangular, so they have a different chord and corresponding chord length at different positions along the span of the aircraft wing. In some examples, the mean chord is a standard mean chord (SMC), where the SMC is defined as wing area divided by wing span. In some instances, the mean chord is a mean aerodynamic chord (MAC), where the MAC is calculated using an integral sum of the chord lengths over the wingspan of the aircraft. To increase the aspect ratio of aircraft wings, the wingspan may be increased. Increasing the wingspan is an effective method of increasing the aspect ratio of aircraft wings and reducing drag and/or enhancing lift of the aircraft.

However, elongated wingspans may pose challenges to existing airport layouts. Airport designs are based on International Civil Aviation Organization (ICAO) Codes A through F, which establish dimensional limits on wingspans, landing gear, width, length, etc. Thus, an airport taxiway and/or gate may have space (e.g., width) limitations, which limit a wingspan of an aircraft that may use the taxiway and/or the gate. For instance, an ICAO Code E airport limits wingspan to less than 65 meters so that aircraft can fit within runways, taxiways and/or gate areas. Most airports are designed to accommodate aircraft up to ICAO Code E, which limits wingspans to less than 65 meters so that aircraft can fit through runways, taxiways, gate areas, etc. Example aircraft disclosed herein employ folding wing tips to provide larger wingspans (e.g., greater than 65 meters) during flight and enable the wingspan of the aircraft to be reduced to accommodate the aircraft the airport infrastructure (e.g., parking areas, taxiways, etc.).

Other aircraft wings employ winglets to improve lift or efficiency. However, winglets are often approximately 30 percent longer in length than a tip extension to obtain similar benefits in lift and efficiency as a tip extension. This results in a heavier winglet, which decreases fuel efficiency.

Example aircraft disclosed herein employ a changeable wingspan that can be greater than space limitations of a taxiway and/or a gate and less than the space limitation of a taxiway and/or a gate. For example, aircraft disclosed herein employ wings that can fold to enable the aircraft to fit within the taxiway and/or the gate. Example aircraft with foldable wings disclosed herein allow lower fuel consumption of an airplane having a wingspan greater than 65 meters (m) (213.3 feet) and capable of operating in a code E airport environment where wingspan is limited to 65 m (213.3 feet). In some examples, example aircraft with foldable wings disclosed herein can be employed with aircraft for other coded airport environments where wingspan is limited to less than 60 m, 50 m, 30 m, and/or any other wingspan.

Additionally, example foldable wings disclosed herein include an actuation system to enable a folding action of the wing. Specifically, the actuation system employs a hinge located outboard of an aileron of the foldable wing. As a result, none of the hydraulic or electrical systems of the actuation system traverse or cross over the hinge into a foldable wing tip. The added weight of hinge system is offset by the fuel savings from the longer and more efficient wing. For example, example aircraft having example folding wings disclosed herein provide a reduction in fuel consumption of 3% to 5%. Further, foldable wings disclosed herein are more weight efficiency than winglets.

FIG.1is a top view of an aircraft100in which aspects of the present disclosure may be implemented. The aircraft100ofFIG.1includes foldable wings102(e.g., a first wing and a second wing) that extend from a fuselage104. A fuselage centerline104ais used herein as a reference for certain dimensional characteristics of the foldable wings102. The aircraft100of the illustrated example is a commercial aircraft. In some examples, the foldable wings102disclosed herein can be implemented with any other example aircraft such as, for example, military aircraft, transport aircraft and/or any other suitable aircraft.

The foldable wings102of the aircraft100are identical in structure and function. Therefore, only one of the foldable wings102of the aircraft100will be discussed in detail for simplicity and brevity. The foldable wing102includes a folding wing tip106(e.g., a foldable portion) and a fixed wing portion108(e.g., a fixed or non-movable portion). The folding wing tip106is a foldable outboard section of the foldable wing102. The fixed wing portion108is a fixed inboard section of the foldable wing102. The fixed wing portion108of the foldable wing102is fixedly and/or rigidly coupled (e.g., directly or indirectly) to the fuselage104of the aircraft100. The folding wing tip106of the foldable wing102is rotatable and/or foldable relative to the fixed wing portion108of the foldable wing102. Rotation and/or folding of the folding wing tip106relative to the fixed wing portion108occurs about an example hinge line or hinge axis110defined by a hinge interface112. The foldable wing102includes a leading edge114and a trailing edge116. Each of the foldable wings102includes control surfaces118(e.g., aerodynamic surfaces, auxiliary airfoils, etc.) adjacent the leading edge and the trailing edge116that may be displaced or extended to change the aerodynamic lift of the aircraft100during takeoff or landing, for example. The control surfaces118include leading edge slats120, ailerons122, flaps124, spoilers, etc.

FIG.2is a front view of the aircraft100ofFIG.1showing each of the foldable wings102ofFIG.1in an example unfolded position200(e.g., a deployed position, an extended position, a spread position, a flight position, etc.). In the unfolded position200, the aircraft100of the illustrated example has a first wingspan202. For example, the first wingspan202can be approximately between 60 meters (196.85 feet) and 80 meters (262.47 feet). In some examples, the first wingspan is approximately 72 meters (236.22 feet). In some examples, the foldable wings102can accommodate smaller sized aircraft. In some examples, the first wingspan202can be approximately between 32 meters (104.97 feet) and 60 meters (196.85 feet). In some such examples, the first wingspan is approximately 35.9 meters (117.78 feet). As used herein, “approximately” means the example value provided is identical to the value stated or within a tolerance (e.g., within a ten percent tolerance). In other examples, the first wingspan202can be less than approximately 65 meters or greater than approximately 80 meters. In the unfolded position200, the folding wing tip106is an extension of the fixed wing portion108. Thus, the fixed wing portion108and the folding wing tip106each provide a substantially continuous airfoil and the hinge interface112does not interfere or affect aerodynamic characteristic(s) or performance of the foldable wing102.

FIG.3is a front view of the aircraft100ofFIG.1showing each of the foldable wings102ofFIG.1in an example folded position300(e.g., a stowed position, a stored position, etc.). In the folded position300, the aircraft100of the illustrated example has a second wingspan302different (e.g., less) than the first wingspan202. For example, the second wingspan302can be approximately between 55 meters and 65 meters. For example, the second wingspan302can be approximately 65 meters (213.25 feet). In other examples, the second wingspan302can be less than 60 meters. For example, the second wingspan302can be approximately between 25 meters and 36 meters. To achieve the folded position300, the folding wing tip106of the foldable wing102is rotated upward relative to the fixed wing portion108via the hinge interface112. The folding wing tip106is positioned at an angle304relative to a horizontal reference306when the folding wing tip106is in the folded position300ofFIG.3. The angle304can be between approximately eighty degrees and one-hundred and five degrees relative to the horizontal reference306. In other examples, the angle304between the folding wing tip106and the fixed wing portion108may be less than or greater than eighty degrees (e.g., ninety degrees, forty-five degrees, one hundred thirty-five degrees, etc.) when the folding wing tip106is in the folded position300. In some examples, the folding wing tip106is oriented substantially vertically relative to the fixed wing portion108. In other examples, to achieve the folded position300, the folding wing tip106can be rotated downward relative to the fixed wing portion108. The varying wingspans (e.g., the first wingspan202and the second wingspan302) enable improved performance during flight, while enabling the aircraft100to meet certain airport limitations. For example, a larger wingspan employed during flight significantly improves fuel efficiency, thereby improving aircraft performance.

FIG.4is an enlarged, partially assembled view of the foldable wing102ofFIGS.1-3in the unfolded position200. The hinge interface112provides a transition402that pivotally couples the folding wing tip106to the fixed wing portion108about the hinge axis110. Specifically, the hinge axis110is provided between the folding wing tip106and an outermost one of the control surfaces118(e.g., the leading edge slat120) positioned on the leading edge of the fixed wing portion108and an outermost one of the control surfaces118(e.g., the aileron122) located at the trailing edge116of the fixed wing portion108.

To move or transition the folding wing tip106between the extended position200and the folded position300, the aircraft100includes a folding wing tip actuation system404. In general, loads (e.g., external loads, moment loads, torsion loads, airloads, etc.) acting upon the folding wing tip106include a weight of the folding wing tip106, dynamic effects of moving a mass of the folding wing tip106, and airloads (e.g., aerodynamic forces) acting upon the folding wing tip106. The folding wing tip actuation system404is designed (e.g., sized) based on power requirements needed to rotate or lift the folding wing tip106and/or to maintain the folding wing tip106in the folded position300against these (and/or other) adverse forces. To reduce (e.g., minimize) loads (e.g., airloads, hinge moments, etc.) imparted to the folding wing tip106and/or the hinge interface112and, thus, power requirements needed to operate the folding wing tip106, a location of the hinge axis110of the illustrated example is positioned relative to a center of mass406and a center of airloading408of the folding wing tip106. Specifically, the center of mass406and the center of airloading408are positioned or located near (e.g., adjacent) the hinge axis110to reduce (e.g., minimize) loads (e.g., lift loads, aerodynamic loads, etc.).

For example, the hinge interface112defines the hinge axis110at a distance410from the fuselage centerline104aof the fuselage104(e.g., a dimensional length in a spanwise direction400a). The distance410can be approximately between 60 meters (98.42 feet) and 65 meters (106.62 feet). For example, the distance410is approximately 62.5 meters (106.62 feet). The center of mass406of the folding wing tip106is located at a distance412from the hinge axis110(e.g., in the spanwise direction400a). In some examples, the distance412can be approximately between 0.40 meters (1.31 feet) and 0.80 meters (2.62 feet). For example, the distance412is approximately 0.60 meters (2.0 feet). Additionally, the center of airloading408(e.g., a center of pressure) is located at a distance414from the hinge axis110. In some examples, the distance414can be approximately between 0.9 meters (2.9 feet) and 1.5 meters (4.9 feet). For example, the distance414is approximately 0.8 meters (2.5 feet). In some examples, the distance414and/or the distance412can be determined as a function (e.g., a percentage) of a semi-span length416and/or a folding wing tip chord length418.

Varying the distance412between the center of mass406and the hinge axis110and/or the distance414between the center of airloading408and the hinge axis110varies (e.g., reduces or increases) loads imparted to the folding wing tip106and, thus, varies (e.g., increases or decreases) power requirements for lifting the folding wing tip106and/or reacting loads imparted to the folding wing tip106. For example, increasing the distance412between the hinge axis110and the center of mass406and/or the distance414between the center of airloading408and the hinge axis110increases loads (e.g., mass loads, air loads, etc.) imparted to the hinge interface112during operation. Likewise, reducing the distance412between the hinge axis110and the center of mass406and/or the distance414between the center of airloading408and the hinge axis110decreases loads imparted to the hinge interface112and, thus, reduces power requirements for rotating or lifting the folding wing tip106between the extended position200and the folded position300and/or the power requirements for maintaining or holding the folding wing tip106in the folded position300.

The foldable wing102of the illustrated example has a semi-span length416(e.g., in the spanwise direction400a) and a folding wing tip chord length418(e.g., in the chordwise direction400b). Specifically, the semi-span length416can be approximately between 3.05 meters (10 feet) and 4.27 meters (14 feet). For example, the semi-span length416can be approximately 3.66 meters (12 feet). The folding wing tip chord length418can be approximately between 2.54 meters (8.33 feet) and 3.35 meters (11 feet). For example, the folding wing tip chord length418can be approximately 3.04 meters (10 feet).

The folding wing tip106of the illustrated example exhibits a raked shape and/or overall geometry. The raked wingtip enhances aerodynamics, thereby increasing fuel efficiency and reducing costs. The folding wing tip106includes a leading edge420having a curved profile (e.g., a swept profile). The swept angle can be approximately between 50 degrees and 60 degrees relative to orthogonal (e.g., a reference perpendicular to the fuselage centerline104a). For example, the foldable wing tip is an aft swept raked tip. The parameters described herein can be related to the example wing tip or other aerodynamic features and/or components described herein.

To this end, due to a radius of curvature of a leading edge420of the folding wing tip106, the folding wing tip106does not require movable control surfaces (e.g., leading edge slats) to prevent airflow separation at high angles of attack that can induce aircraft stall. Providing the folding wing tip106without moving control surfaces enables formation of the foldable wing102without motive equipment (e.g., motors, hydraulic systems, etc.) to span across the hinge axis110and/or the hinge interface112that may otherwise be needed to deploy or move the control surfaces of a wing tip. To this end, locating or positioning the hinge axis110between a curved portion of the leading edge420and the control surface118of the fixed wing portion108of the foldable wing102significantly reduces complexity of the hinge interface112because the folding wing tip106can be formed without movable control surfaces (e.g., the control surfaces118, a slat, etc.). Additionally, the hinge axis110is positioned outboard of the aileron122to enable fuel jettison from a port424of the foldable wing102. Here, the port424is positioned a distance approximately between 0.25 feet and 1.00 feet from an end426of the control surface118of the trailing edge116of the fixed wing portion108. In other examples, the folding wing tip106can be a straight wing tip (e.g., a non-raked wing tip). In some examples where the folding wing tip106has a straight profile, the folding wing tip106can include movable control surfaces to protect against aircraft stall. In some such examples, at least a portion of a control system (e.g., a motor, a hydraulic system, etc.) can be in the folding wing tip106.

Additionally, due to the raked folding wing tip106, the location of the hinge axis110can positioned at the distance410from the fuselage centerline104athat enables the transition402to provide a housing for aircraft components. For example, the transition402and/or the fixed wing portion108provides can house the folding wing tip actuation system404that can include one or more actuators, transmissions and/or drives. Additionally, the transition402and/or the fixed wing portion108accommodates drive components (e.g., motors, hydraulic systems, drive shafts, transmissions, etc.) that operate the control surfaces118(e.g., the slats, the aileron) of the fixed wing portion108. In this manner, no component (e.g., drive systems, etc.) of the folding wing tip actuation system404and/or components of the control surfaces118traverses the hinge interface112and/or is positioned or located (e.g., housed) in the folding wing tip106. In some examples, a wire or cable (e.g., a wire bundle) can traverse the hinge interface112to electrically couple to a light (e.g., a tip light) supported by the folding wing tip106.

FIG.5is a partially, assembled view of the foldable wing102ofFIGS.1-4. To enable the folding wing tip106to pivot or rotate relative to the fixed wing portion108, the hinge interface112includes one or more hinges. For example, the hinge interface112includes a first hinge502(e.g., a fore hinge) and a second hinge504(e.g., an aft hinge). However, in some examples, the hinge interface112includes only one hinge (e.g., the second hinge504) or more than two hinges (e.g., three hinges, four hinges, etc.). The first hinge502and the second hinge504are located along the folding wing tip chord length418and the first hinge502is spaced relative to the second hinge504in the chordwise direction400b(e.g., in the fore-aft direction). Specifically, the first hinge502is spaced horizontally relative to the second hinge504in the fore-aft direction (e.g., chordwise direction400b). For example, the first hinge502is spaced from the second hinge504a distance506of approximately between 0.8 meters (2.6 feet and 1.0 meters (3.3 feet). For example, the distance506is approximately 0.86 meters (2.83 feet).

The first hinge502and the second hinge504are coupled to and/or extend from the folding wing tip106toward the fixed wing portion108. For example, the first hinge502and the second hinge504are coupled to a tip wing box508of the folding wing tip106and a fixed wing box510of the fixed wing portion108. For example, the first hinge502and the second hinge504can be coupled to a closeout wing rib of the tip wing box508and a front spar512and/or a rear spar514of the fixed wing box510. The first hinge502is positioned or located near (e.g., adjacent) a leading-edge interface511(e.g., an intersection) between the leading edge420of the folding wing tip106and the folding wing tip chord length418. The second hinge504is positioned or located between the first hinge502and a trailing-edge interface513(e.g., an intersection) between a trailing edge515of the folding wing tip106and the folding wing tip chord length418. For example, the first hinge502is spaced from the leading-edge interface511a distance517of approximately between 0.4 meters (1.3 feet) and 0.7 meters (2.3 feet). For example, the distance517is approximately 0.5 meters (1.6 feet). In this example, the distance517is measured between the leading-edge interface511and a center (e.g., a longitudinal axis525) of the first hinge502. The second hinge504is positioned aft of the first hinge502. For example, the second hinge504is positioned or located at a midpoint of the folding wing tip chord length418. In some examples, the first hinge502is spaced from the leading-edge interface511a distance519of approximately between 1.0 meters (3.3 feet) and 1.8 meters (5.9 feet). For example, the distance519is approximately 1.4 meters (4.6 feet). In this example, the distance519is measured between the leading-edge interface511and a center (e.g., a longitudinal axis525) of the second hinge504. Thus, the second hinge504is located at or adjacent (e.g., within 10% of) a midpoint of the folding wing tip chord length418and the first hinge502is positioned fore of the second hinge504in the chordwise direction400bby any desired distance. In some examples, the second hinge504can be positioned at any location between the leading edge420and a trailing edge515of the folding wing tip106(e.g., along the folding wing tip chord length418). In some examples, the first hinge502can be positioned adjacent or at the midpoint of the folding wing tip chord length418or at any other location between the leading edge420and a trailing edge515of the folding wing tip106(e.g., along the folding wing tip chord length418). In some such examples where the first hinge502is positioned adjacent or at the midpoint, the second hinge504can be located aft of the first hinge502in the chordwise direction400bby any desired distance.

The folding wing tip106imparts loads (moment loads, torsion loads, etc.) to the fixed wing portion108. To react the loads, the first hinge502of the illustrated example provides a first torque box and the second hinge504provides a second torque box. Each of the first hinge502and the second hinge504has a dimensional length518(e.g., a first dimension) in the spanwise direction400aand a dimensional width516(e.g., a second dimension) in the chordwise direction400b. For example, the dimensional length518(e.g., a torque box length) of each of the first hinge502and the second hinge504is approximately between 0.4 meters (1.3 feet) and 0.6 meters (2.0 feet). For example, the dimensional length518is 0.51 meters (1.67 feet). Each of the first hinge502and the second hinge504has the dimensional width516(e.g., a dimensional width, a torque box width) of approximately between 0.20 meters (0.67 feet) and 0.30 meters (1.00 feet). For example, the dimensional width516is 0.25 meters (0.83 feet).

To provide the first and second torque boxes, the first hinge502and the second hinge504can be formed by a plurality of ribs (e.g., wing ribs), chords, and/or other wing frame structure(s). For example, the first hinge502includes a first wing rib520and a second wing rib522defining the first torque box. The second hinge504of the illustrated example includes a third wing rib524and a fourth wing rib526defining the second torque box. The first wing rib520is spaced from the second wing rib522to define the dimensional width516of the first hinge502and the third wing rib524is spaced from the fourth wing rib526to define the dimensional width516of the second hinge504. Each of the first, second, third and fourth wing ribs520-526at least partially spans across the hinge interface112between the folding wing tip106and the fixed wing portion108. For example, the wing ribs520-526span across the hinge interface112with the dimensional length518in the spanwise direction400a(e.g., the dimensional length518) that is greater than the dimensional width516in which the wing ribs520-526extend in the chordwise direction400b. As a result, the dimensional length518is greater than the dimensional width516. In other words, the wing ribs520-526extend from the folding wing tip106in a direction that is substantially perpendicular to the fuselage centerline104aof the fuselage104. Specifically, each of the wing ribs520-526has a longitudinal axis525that extends between the folding wing tip106and the fixed wing portion108in a direction substantially perpendicular to the fuselage centerline104aof the aircraft100. As used herein, substantially perpendicular means either perfectly perpendicular (e.g., exactly ninety degrees) or almost perpendicular (e.g., within a certain percentage of perfectly perpendicular, within 10% of perpendicularity).

To enable the hinge interface112to provide a (e.g., primary) load path to transfer loads and/or forces from the folding wing tip106to the fixed wing portion108, the first hinge502and the second hinge504are coupled to the tip wing box508of the folding wing tip106and the fixed wing box510of the fixed wing portion108. The first hinge502is coupled to the front spar512of the fixed wing box510and the second hinge504is coupled to the rear spar514of the fixed wing box510. Likewise, the first hinge502is coupled to a front spar528of the tip wing box508and the second hinge504is coupled to a rear spar530of the tip wing box508.

Specifically, the first wing rib520is coupled (e.g., attached indirectly or directly) to a first side or structure512aof the front spar512of the fixed wing box510and a first side or structure528aof the front spar528of the tip wing box508. The second wing rib522is coupled (e.g., attached indirectly or directly) to a second side or structure512b(e.g., a closeout rib) of the fixed wing box510and a second side or structure528b(e.g., a closeout rib) of the tip wing box508. Likewise, the third wing rib524is coupled (e.g., attached indirectly or directly) to a first side or structure514aof the rear spar514of the fixed wing box510and a first side or structure530aof the rear spar530of the tip wing box508. The fourth wing rib526is coupled (e.g., attached indirectly or directly) to a second side or structure514b(e.g., a closeout rib) of the fixed wing box510and a second side or structure530b(e.g., a closeout rib) of the tip wing box508. The first hinge502(e.g., the first wing rib520and the second wing rib522) is in a non-parallel or a non-perpendicular orientation relative to the front spar512of the fixed wing box510. The first hinge502(e.g., the first and second wing ribs520-522) is positioned at an angle (between zero degrees and ninety degrees) relative to the front spar512. The second hinge504(e.g., the third wing rib524and the fourth wing rib526) is in a non-parallel or a non-perpendicular orientation relative to the rear spar514of the fixed wing box510. The second hinge504(e.g., the third wing rib524and the fourth wing rib526) is positioned at an angle (between zero degrees and ninety degrees) relative to the rear spar514.

To enable rotation (e.g., pivotal movement) of the folding wing tip106and the fixed wing portion108, the hinge interface112of the foldable wing includes a plurality of hinge pins534. Respective ones of the hinge pins534are coupled to or supported by respective ones of the wing ribs520-526. Thus, the hinge pins534are supported by the wing ribs520-526. For example, each of the first, second, third and fourth wing ribs520-526includes a hinge pin aperture that aligns along the hinge axis110to receive or support respective ones of the hinge pins534. In some examples, a unitary hinge pin is provided that is coupled to or supported by at least one of the wing ribs520-526. Thus, the hinge axis110passes through the first wing rib520, the second wing rib522, the third wing rib524, and the fourth wing rib526.

To prevent rotation (e.g., lock rotation) of the folding wing tip106relative to the fixed wing portion108, the hinge interface112of the foldable wing102includes a latch interface536. The latch interface536includes a plurality of latch pins542. Each of the wing ribs520-526includes a latch pin aperture that aligns along a latch axis538to receive respective ones of the latch pins542. In some examples, the latch interface536includes one latch pin, two latch pins or any other number of hinge pins (e.g.,3,4,5,6, etc.). The latch pins542are movable between a latched position to prevent rotation of the folding wing tip106relative to the fixed wing portion108and an unlatched position to enable rotation of the folding wing tip106relative to the fixed wing portion108. For example, in the latched position, the latch pins542engage respective ones of the wing ribs520-526to prevent rotation of the folding wing tip106. In the unlatched position, the latch pins542release or move away from the respective ones of the wing ribs520-526to allow rotation of the folding wing tip106. To move the latch pins between the latched and unlatched position, the foldable wing102includes a plurality of actuators. Respective ones of the actuators move respective ones of the latch pins542between the latched and unlatched positions.

The latch axis538is offset (e.g., laterally offset) relative to the hinge axis110. For example, the latch axis538is spaced from the hinge axis110a distance540approximately between 0.25 meters (0.83 feet) and 0.40 meters (1.31 feet). For example, the distance540can be approximately 0.32 meters (1.05 feet). The latch axis538is located from the fuselage centerline104aa distance539of approximately between 32.0 meters (105.0 feet) and 32.2 meters (105.6 feet). Additionally, the latch axis538is substantially parallel relative to the hinge axis110and/or the fuselage centerline104a. As used herein, substantially parallel means perfectly parallel or almost perfectly parallel (e.g., within 10 degrees of perfectly parallel). For example, the hinge axis110and the latch axis538extend in (e.g., are parallel relative to) a fore-aft direction of the aircraft100(e.g., a direction of flight). In this manner, the folding wing tip106can be oriented to reduce (minimize) air loads imparted to the folding wing tip106when in the folded position300. However, in some examples, the hinge axis110and/or the latch axis538can be positioned at an angle relative to the fore-aft direction (e.g., the fuselage centerline104a). For example, the hinge axis110and/or the latch axis538can be positioned parallel relative to a lateral inboard edge544of the fixed wing portion108. In some examples, the hinge axis110and/or the latch axis538can have any other angle and/or orientation relative to the fore-aft direction and/or the spanwise direction400a. In some examples, the hinge axis110is not parallel relative to the latch axis538.

Additionally, the hinge axis110is positioned outboard relative to the latch axis538. For example, the latch axis538is positioned closer to fuselage centerline104athan the hinge axis110. In other words, the hinge axis110is located between the folding wing tip106and the latch axis538, and the latch axis538is located between the fixed wing portion108and the hinge axis110. The location of the hinge axis110outboard of the latch axis538reduces the distance412between the center of mass406and the hinge axis110and the distance414between the center of airloading408and the hinge axis110, thereby reducing (e.g., minimizing) a lifting load needed to move the folding wing tip106between the extended position200and the folded position300.

FIG.6is an enlarged view of the foldable wing102ofFIG.5. As noted above, the hinge interface112provides a (e.g. primary) load path600to transfer a load from the folding wing tip106to the fixed wing portion108(e.g., to the fixed wing box510). For example, the hinge interface112provides a (e.g., primary) wing bending/spanwise load path and a stream/chord wise stiffening load path. To this end, the hinge interface112utilizes the wing ribs520-526to transmit loads across the hinge interface112. For example, the hinge interface112provides load paths from the tip wing box508to the fixed wing box510. In some examples, each of the wing ribs520-526can transfer the loads across the hinge interface112, thereby providing a fail-safe system. In this manner if one of the wing ribs520-526becomes damaged (e.g., the first wing rib520becomes damaged) and cannot transfer loads, the other ones of the wing ribs520-526(e.g., the second wing rib522, the third wing rib524, the fourth wing rib526) provide the load path600to distribute and transfer the loads to the fixed wing box510. Additionally, the hinge interface112utilizes the hinge pin534and the latch pins542to react loads across the hinge interface112and the latch interface536. Employing two or more hinges significantly improves the structural integrity of the hinge interface112. For example, failure of one hinge enables the other ones of the hinges to take-up the loads. Thus, the hinge interface112employing the first hinge502and the second hinge504is configured to provide redundant, fail-safe load paths. However, in some examples, the hinge interface112can be configured with only one hinge to pivotally couple the folding wing tip106to the fixed wing portion108. In some examples, the single hinge can be positioned at a midpoint of the folding wing tip chord length418. In some examples, the single hinge can be positioned at any location between the leading edge420and a trailing edge602of the folding wing tip106(e.g., along the folding wing tip chord length418).

FIG.6Bis a partial view of the foldable wing102ofFIGS.1-6Ashown in the folded position300. The hinge interface112facilitates inspection of the structural components associated with the hinge interface112. For example, in the folded position300, the folding wing tip106exposes or enables access to at least some portions of the first hinge502and the second hinge504(e.g., the wing ribs520-526and/or other wing ribs, chords, or other structure adjacent the hinge axis110). Such configuration enables visual inspection of the hinge interface112(e.g., given that some of the components are at least partially exposed when the folding wing tip106is in the folded position300). Such configuration significantly reduces maintenance time needed to inspect the hinge axis110and, thus, reduces maintenance costs.

FIG.7is a partial, schematic side view of the foldable wing102ofFIGS.1-6shown in the folded position300. The foldable wing102can be configured with a margin702to maintain the aircraft100in compliance with an International Civil Aviation Organization (ICAO) dimensional limitation700due to bending of the foldable wing102when the aircraft100is parked or moving along a taxiway, account for fuel weight of fuel stored in the folding wing tip106and/or the fixed wing portion108, and/or account for bending due to wind loads. As shown inFIG.7, an outermost end704of the fixed wing portion108and an outermost end706of the folding wing tip106are within the ICAO dimensional limitation700when the foldable wing102is in the folded position300.

As notated above, Airport designs are based on International Civil Aviation Organization (ICAO) Codes A through F, which establish dimensional limits on wingspans, landing gear, width, length, etc. Most airports are designed to accommodate aircraft up to ICAO Code E, which limits wingspans to less than 65 meters so that aircraft can fit through runways, taxiways, gate areas, etc. The folding wing tip106of the aircraft100enables the aircraft100to provide the first wingspan202(FIG.2) that is less than or equal to the Code F wingspan limitation802, but greater than a Code E wingspan limitation804(e.g., greater than 65 meters). The folding wing tip106of the aircraft100enable the first wingspan202to be reduced to the second wingspan302(FIG.3) so that the aircraft can fit within the current airport infrastructure (e.g., parking areas, taxiways, etc.) in compliance with ICAO Code E size limitations (e.g., under 65 meters), for example. In some examples, the folding wing tips106of each foldable wing102are about 12 feet in length. As such, the first wingspan202(FIG.2) can be decreased by about 24 feet by folding the folding wing tips106of the foldable wings102.

In some examples, the foldable wings102disclosed herein can be implemented with other types and/or sized aircrafts. For example, the foldable wings102can be structured to provide the first wingspan202of approximately between 30 meters and 65 meters when the foldable wings102are in the unfolded position200and provide the second wingspan302of approximately between 25 meters and 60 meters when the foldable wings102are in the folded position200. In some examples, the foldable wings102disclosed herein can be structured to provide any suitable distance of the first wingspan202and the second wingspan302by varying (e.g., increasing) the semi-span length416of the folding wing tip106, the folding wing tip chord length418, the length of the fixed wing portion108, and/or the distance410of the hinge axis110relative to the fuselage centerline104a.

FIG.8is a front view of the aircraft100with reference to dimensional limitations of a first code of the International Civil Aviation Organization (ICAO) and dimensional limitations of a second code of the ICAO. For example, the first code is representative of Code E dimensional requirements and the second code is representative of Code F dimensional requirements. The aircraft100complies with ICAO Code E and Code F limitations including, for example, landing clearance limitations, obstacle clearance limitations, and snow removal limitations. In some examples, the aircraft100(e.g., or other types of aircraft) can be structured with the foldable wings102to comply with other codes of the ICAO (e.g., Code A-D limitations) and/or any other limitation(s).

FIG.9is a front view of the aircraft100relative to an ICAO Code E landing clearance limitation900. The aircraft100satisfies an inner approach limitation (e.g. 120 meters for a Code E approach) when the foldable wings102are in the deployed position200and satisfies (e.g. clears or does not extend beyond) an obstacle free zone902(OFZ) when the foldable wings102are in the stored position300.

FIG.10is a front view of the aircraft100relative to an ICAO Code F landing clearance limitation1000.

FIG.11is a schematic view of the aircraft100relative to ICAO Code E obstacle clearance limitation1100.

FIG.12is a schematic view of the aircraft100relative to ICAO Code F obstacle clearance limitation1200. The foldable wings102of the aircraft100of the illustrated example is formed to comply with an obstacle free zone limitation of the ICAO. However, in some examples in which compliance with the ICAO codes is not needed, the folding wing tips106can be formed with a longer dimensional length (e.g., the semi-span length416and/or the folding wing tip chord length418) and be structurally supported with the foldable wing102.

FIG.13is a schematic illustration of the aircraft100and an aircraft1300relative to ICAO Code E and Code F taxiway to taxiway separation distances. Thus, the aircraft1300can be identical to the aircraft100ofFIGS.1-8.

At least some of the aforementioned examples include one or more features and/or benefits including, but not limited to, the following:

In some examples, an aircraft includes a fixed wing portion and a foldable wing tip defining a foldable wing tip chord length. A hinge interface pivotally couples the foldable wing tip and the fixed wing portion. The hinge interface has a first hinge and a second hinge defining a hinge axis that is substantially parallel to a fuselage centerline. Each of the first hinge and the second hinge has a first dimension in a spanwise direction and a second dimension in a chordwise direction. The first dimension is greater than the second dimension. The second hinge is positioned adjacent a midpoint of the foldable wing tip chord length and the first hinge being positioned fore of the second hinge.

In some examples, the first hinge defines a first torque box having a first wing rib and a second wing rib, the first wing rib being attached to a front spar of a fixed wing box of the fixed wing portion and a front spar of a foldable wing box of the foldable wing tip, the second wing rib being attached to a closeout rib of the fixed wing box of the fixed wing portion and a closeout rib of the foldable wing box of the foldable wing tip.

In some examples, the first hinge is non-parallel relative to the front spar of the fixed wing box.

In some examples, the hinge interface includes a second hinge defining the hinge axis, the first hinge and the second hinge are spaced apart in a chordwise direction

In some examples, the first hinge is spaced from the second hinge in a chordwise direction by a distance approximately between 0.8 meters (2.6 feet) and 1.0 meters (3.3 feet).

In some examples, the second hinge defines a second torque box having a third wing rib and a fourth wing rib, the third wing rib being attached to a rear spar of the fixed wing box of the fixed wing portion and a rear spar of the foldable wing box of the foldable wing tip, the fourth wing rib being attached to a closeout rib of the fixed wing box of the fixed wing portion and a closeout rib of the foldable wing box of the foldable wing tip.

In some examples, the second hinge is non-parallel relative to the rear spar of the fixed wing box.

In some examples, at least one of the first hinge or the second hinge provides a primary load path between the foldable wing tip and the fixed wing portion.

In some examples, the hinge interface is located outboard relative to an outermost leading edge slat and an outermost aileron of the fixed wing portion.

In some examples, a latch interface defining a latch axis substantially parallel relative to the hinge axis, the hinge axis being spaced from the latch axis by a distance of approximately between 0.25 meters (0.83 feet) and 0.40 meters (1.31 feet).

In some examples, the hinge axis is positioned between the foldable wing tip and the latch axis, and the latch axis is positioned between the hinge axis and the fuselage.

In some examples, the hinge axis is positioned closer to at least one of a center of mass or a center of airloading of the foldable wing tip than the latch axis.

In some examples, the foldable wing tip has a semi-span length of approximately between 10 feet and 14 feet and a foldable wing tip chordwise length of approximately between 9 feet and 11 feet.

In some examples, the aircraft has a first wingspan when the foldable wing tip is in an extended position and a second wingspan when the foldable wing tip is in a folded position, the first wingspan being greater than 65 meters and the second wingspan being less than 65 meters.

In some examples, wherein the first dimension in a spanwise direction is approximately between 0.4 meters (1.3 feet) and 0.6 meters (2.0 feet) and the second dimension in the chordwise direction is approximately between 0.20 meters (0.67 feet) and 0.30 meters (1.00 feet).

In some examples, an aircraft includes a wing having a fixed wing portion and a foldable wing tip. A hinge interface pivotally couples the foldable wing portion to the fixed wing portion. The hinge interface includes a first wing rib and a second wing rib spaced from the first wing rib to define a first hinge. The first wing rib supports a first hinge pin and the second wing rib supports a second hinge pin. Each of the first wing rib and the second wing rib has a longitudinal axis to extend between the foldable wing tip and the fixed wing portion in a direction substantially perpendicular to a fuselage centerline of the aircraft.

In some examples, the hinge interface includes a third wing rib and a fourth wing rib spaced from the third wing rib to define a second hinge, the third wing rib to support a third hinge pin and the fourth wing rib to support a fourth hinge pin, each of the third wing rib and the fourth wing rib having a longitudinal axis to extend between the foldable wing tip and the fixed wing portion in a direction substantially perpendicular to the fuselage centerline of the aircraft.

In some examples, the hinge interface defines a hinge axis passing through the first wing rib, the second wing rib, the third wing rib, and the fourth wing rib, the hinge axis is spaced from a center of mass of the foldable wing tip a distance of approximately between 0.40 meters (1.31 feet) and 0.80 meters (2.62 feet).

In some examples, the second hinge is positioned at a midpoint of a foldable wing tip chord length and the first hinge is positioned a distance from the second hinge in the chordwise direction.

In some examples, an aircraft includes a first wing having a first fixed portion and a first foldable portion, and a second wing having a second fixed portion and a second foldable portion. The first wing and the second wing to provide a first wingspan when the first foldable portion and the second foldable portion are in extended positions. The first wing and the second wing to provide a second wingspan when the first foldable portion and the second foldable portion are in folded positions. The first wingspan is greater than approximately 65 meters and the second wingspan is less than approximately 65 meters. Each of the first and second foldable portions rotates about a hinge axis that is substantially parallel relative to a fuselage centerline.

In some examples, the hinge axis is spaced from a center of mass of the first foldable portion a distance of approximately between 0.40 meters (1.31 feet) and 0.80 meters (2.62 feet).

In some examples, a method includes moving a foldable wing tip relative to a fixed wing portion of an aircraft about a hinge axis that is substantially parallel relative to a fuselage centerline between a stowed position to provide a first wingspan and an extended position to provide a second wingspan greater than the first wingspan, where the foldable wing tip includes a hinge interface to pivotally couple the foldable wing tip and the fixed wing portion. The hinge interface has a first hinge and a second hinge. The second hinge is positioned adjacent a midpoint of the foldable wing tip chord length and the first hinge is positioned fore of the second hinge.

In some examples, the method includes moving the foldable wing tip to the stowed position during a taxiing event.

In some examples, the method includes moving the foldable wing tip to the extended position during flight to enhance an aerodynamic characteristic of the aircraft.

Although certain example methods, apparatus and articles of manufacture have been described herein, the scope of coverage of this disclosure is not limited thereto. On the contrary, this disclosure covers all methods, apparatus and articles of manufacture fairly falling within the scope of the claims.