Technical | Wing Group
Wing Group Description
The wing structure is the conventional full cantilever type. It consists of an inverted, gull-wing shaped center section which supports the main landing gear and two tapered outer panels. The outer panels are of composite construction, with an alclad, stressed skin leading edge, and a fabric covered aft section supported by internal ribs. The “D” shaped leading edge consists of the alclad sheet covering, suitably reinforced by stiffeners and ribs, which forms a torsion brace for the single main beam. Additional ribs and supports are located wherever an aileron or flap hinge exists.
The center section is constructed in the form of a box beam, with a main beam which extends across the fuselage and supports the leading edge loads, a auxiliary rear beam and a stiffened upper skin continuous from the fuselage out to the hinge rib The lower surface is discontinuous because of the wheel well cut-out. The skin plating is entirely flush riveted and bolted. (Fig 13)
The inverted, gull-wing shaped center section consists of a curved main beam which extends through the fuselage, and a rear beam on each side of the fuselage which extends from the fuselage skin line to the center section end rib. Te reinforced upper surface covering extends from the fuselage out to the hinge rib. The lower surface is similar to the upper surface except for the large wheel well cutout. The shear loads in the upper and lower skins are transmitted to the fuselage side panel by corner attach angles.
The outer end of the nose section is reinforced to transmit the landing loads through ribs and skin plating to the main beam and upper covering. The inboard end, adjacent to the fuselage, is removable fairing which surrounds the oil cooler and air intake vanes. Flap gap covering on the upper surface and doors on the lower surface are located aft of the auxiliary rear beam. The flap gap covering is reinforced by former ribs. Chord ribs, located at the outer end of the center section and on either side of the wheel well, serve to distribute the shear loads.
Access to the interior of the center section is provided by a removable truss in the inboard interbeam rib. This opening, which is large enough to admit a man’s head and shoulders, is reached through the wheel well and is closed by a cloth cover provided with zipper fasteners. Removal of the upper and lower air duct panels provides access to the inboard portion of the main beam.
:The Inverted, Gull-Wing Shaped Center Section consists of a curved main beam which extends through the fuselage, and a rear beam on each side of the fuselage which extends from the fuselage skin line to the center section end rib. Te reinforced upper surface covering extends from the fuselage out to the hinge rib. The lower surface is similar to the upper surface except for the large wheel well cutout. The shear loads in the upper and lower skins are transmitted to the fuselage side panel by corner attach angles.
The outer end of the nose section is reinforced to transmit the landing loads through ribs and skin plating to the main beam and upper covering. The inboard end, adjacent to the fuselage, is removable fairing which surrounds the oil cooler and air intake vanes. Flap gap covering on the upper surface and doors on the lower surface are located aft of the auxiliary rear beam. The flap gap covering is reinforced by former ribs. Chord ribs, located at the outer end of the center section and on either side of the wheel well, serve to distribute the shear loads
Access to the interior of the center section is provided by a removable truss in the inboard interbeam rib. This opening, which is large enough to admit a man’s head and shoulders, is reached through the wheel well and is closed by a cloth cover provided with zipper fasteners. Removal of the upper and lower air duct panels provides access to the inboard portion of the main beam
Skin - Center Section: The Leading Edge Skin is divided into two sections: the heavy gage, stringer supported, outboard position over and adjacent to the wheel well and the stiffened, lighter gage inboard portion which forms a part of the air duct panels. (Fig 14) The landing gear doors as well as the fixed and removable fairings form a part of the lower skin. The skin panels between the main beam and the auxiliary rear beam to the center section wing are constructed of thick gage sheet, reinforced with harp-shaped stiffeners spot welded in position. The upper skin extends beyond the auxiliary rear beam to form the flap gap cover. A light gage tunnel skin covers the space between upper and lower skins. Triangular shaped former ribs that tie into the aft side of the auxiliary rear beam stiffen both skins.
Stringers and Stiffeners: Hat-shaped stringers are riveted to the outboard leading edge skin and spotwelded to the skin panels between the main and rear beams. Stiffeners are spotwelded to the skin of the upper air duct panel and both spotwelded and riveted to the lower air duct panel skin. These stiffeners are made of alclad sheet. (Fig. 22) (Fig. 16)
Ribs: The Center Section Wing Ribs are classified, regardless of their location, as three general types: trussed ribs, reinforced ribs and former ribs.
The leading edge ribs of the center section are both truss type and reinforced ribs. The inboard leading edge rib supports the air duct panels, and the diagonal ribs support the landing gear knuckle fitting.
There are two interbeam ribs on each side between the main and rear auxiliary beams, and these are located at the outer end of the center section and inner end of the wheel well. The end rib is constructed of a solid sheet riveted to an extruded flange section. Vertical bent up angles are spot welded to the web for stiffening. The flanges of the inner rib are made of hat sections and a heavy gage cap strip, shaped like a dinosaur’s tail. The partial sheet web is attached to a removable truss. The members of the truss are made of extruded sections. Suitable vertical stiffeners are located on the partial web to distribute the concentrated loads of the truss members.
Former ribs are attached to the auxiliary rear beam forward of the center section flaps. These former ribs have reinforcing heads and lightening holes, and are attached to the web of the auxiliary rear beam by means of channels.
Main Beam: The Main Beam is constructed of extruded flange angles reinforced with thick plates, and a thick gauge shear web stiffened by hat-shaped vertical stiffeners. Forged wing hinge fittings to which the outer panel is attached are bolted to the upper and lower beam flanges. A forged vertical stiffener is placed between the beam flanges to stabilize the upper and lower fittings against inclined loads. Forgings in the form of stiffeners are located where the landing gear ribs attach to the beam in order to redistribute the highly concentrated loads.
Rear Beam: The Rear Beam consists of a solid sheet web with bent up flanges. These flanges have both solid bar reinforcements and bent up sheet angle reinforcements. The web is butt spliced at the intersection of the beam and the inner wheel well rib. A bent up sheet angle reinforcement extends the whole length of the upper flange, and one extends from the butt splice gusset inboard to the vertical stiffener joining the beam to the fuselage structure. Local bar reinforcements are attached to the rear outstanding leg of the upper and lower flanges and to the front vertical leg of the upper flange.
Leading Edge Hinge Beam: The leading edge hinge beam is located in the leading edge portion of the center section wing (Fig 22). The leading edge hinge fitting is attached to the outboard end of the beam. The Beam serves to transmit loads from the leading edge hinge fitting to the center section. The beam is constructed of a sheet web and bent up angle flanges and is reinforced by stiffeners.
Landing Gear Doors: The landing gear doors, which enclose the retracted main landing gear, are constructed of an outer skin reinforced by former ribs, two longitudinal edge-stiffening channels, and a spot welded internal covering panel (Fig 33). The doors close the wheel wells and make the lower wing surface continuous. Although not structurally critical, the landing gear doors are subjected to local air loads in flight. These doors can be severely damaged when an emergency landing without the main landing gear is attempted.
Center Section Fuselage Attach Angles: The center section fuselage attach angles are made of extruded sections. They are located at the intersection of the fuselage and the upper and lower center section trailing edge skins. In addition to the usual rivets, all rivets attaching the upper angle to the fuselage from Station 138.6 to Station 108 are hi-shear rivets. There are no hi-shear rivets on the lower attach angles (Fig 22).
The outer panels are of composite construction with alclad sheet leading edge skin and a fabric covered trailing edge. The gun bay doors o the upper trailing edge surface of the wing and the skin supporting the rocket installation of the lower trailing edge surface of the wing are also alclad sheet.
The “D” shaped leading edge of the outer panel is built as an integral unit
which consists of the main beam, former and reinforced type ribs and stringers.
Aft of the main beam the fabric skin is supported by truss type and
reinforced type ribs which are bolted and riveted to the main beams and to the
trailing edge former.
The “D” shaped leading edge of the outer panel is built as an integral unit which consists of the main beam, former and reinforced type ribs and stringers. Aft of the main beam the fabric skin is supported by truss type and reinforced type ribs which are bolted and riveted to the main beams and to the trailing edge former.
Skin: The leading edge skin of the outer panel wing is subjected to high loads in flight. It extends from the leading edge hinge fitting outboard to the wing tip and from the upper flange of the main beam around the leading edge to the lower main beam flange. Aft of the main beam, the outer panel wing is fabric covered, with the exception of the gun bay doors and ammunition boxes on the upper surface of the wing, and the skin supporting the rocket installation on the lower surface of the wing (Fig 36).
Stringers: The leading edge stringers of the outer panel are extruded or rolled section riveted to the skin. In general, they pass through cutouts in the leading edge ribs, except ribs at Station 29¾ and Station 86, as is clearly shown on figure 39. The extruded shapes of the leading edge stringers are shown on figure 41.
Ribs: (Fig 42) The three types of ribs in the outer panel are classified as former ribs, reinforced ribs and trussed rubs.
The critical stations of the outer panel leading edge are from Station 0 to Station 29 3/4, and Stations 71, 86, 107 and 128. The ribs at these points receive the greatest load during flight. Ribs at Stations 128, 107 and 71 support the aft ribs which transmit the aileron loads. Ribs support the aft ribs which transmit the aileron loads. Ribs inboard from Station 29 3/4 to Station 0 are supports for the machine gun blast tubes and flap hinge loads. In the leading edge, all ribs have bent up sheet flanges which attach to the skin and, with the exception of ribs at Stations 0, 29 3/4, and 86, have cutouts to permit the lateral stringers to pass through. The webs of some ribs which have stringer cutouts in the flanges are stiffened with formed beads which follow the contour of the rib flanges and are just below the cutouts. The reinforced ribs are stiffened with bent up channel or angle pieces.
The flanges of the trailing edge ribs have fabric retaining hooks to permit attachment of the fabric covering. All trailing edge rib assemblies are riveted together. The solid reinforced ribs are the main carrying members for the aileron or flap loads. These reinforced ribs are located at Stations 128, 107, 71, 32, 50, 30 1/4, and 3 1/4.
Ammunition box bulkheads extend from Station 30 1/4 to Station 71 11/32 and are located between the ammunition boxes.
Main Beam: The outer panel main beam is a riveted assembly composed of extruded aluminum alloy flanges and an alclad sheet web. The web is stiffened vertically on both sides of the beam by means of bent up sheet sections. These stiffeners tie into the legs of both upper and lower beam flanges. Bar reinforcements are inserted in the upper and lower beam flanges at the inboard end for the attachment of the wing hinge fittings. The fittings are bolted to the fins of the beam flanges with standard countersunk head bolts. The web is suitable reinforced at these fittings by extra gage web thickness and a vertical stiffener. Holes in the web of the beam provide access to the leading edge section. (Fig 52)
Auxiliary Hinge Beam: The auxiliary hinge beam carries the loads from the leading edge hinge fitting into the structure of the outer panel. It is located forward of the main beam and its upper flange extends from Station 2 to just outboard of Station 29 ¾. The lower reinforced flange and the web extend from Station 2 to Station 13 ½. Bolted to the upper and lower flanges and to the web is the leading edge hinge fitting. The web is reinforced by vertical stiffeners and the blast tube of the inboard gun passes through it. (Fig 56)
Wing Tip: The removable wing tip is fabricated completely of cloth type plastic. There are five former bulkheads supporting the wing tip skin. The tip is attached by basket nuts riveted to the inside of the tip skin at Station 149, which receive screws through the leading and trailing edges of the outer panel structure. (Fig 57)
Gun Bay Doors and Ammunition Boxes: The gun bay doors are located between Station 3 ¼ and Station 30 ¼. (Fig 36) (Fig 58) The forward half of the front gun bay door is hinged to the main beam. The aft half of the front gun bay door is hinged to the forward half. The rear gun bay door is removable but not hinged. It fits flush against the front half of the front gun bay door and extends
to the trailing edge just forward of the flaps. The gun bay doors are constructed of skin and riveted stiffener reinforcements. In some areas bent up inner skin or reinforcing sheet provides further stiffening.
Outboard of the gun bay doors, from Station 30 ¼ to Station 71 11/32, the six ammunition boxes are locked into place by two gap cover doors. The gap cover doors are constructed of skin, reinforcing extruded sections and bent up inner skin. The hinged ammunition box covers are reinforced by a continuous waffle section and a bent up inner skin. Both rivets and spotwelds are used in the construction of the gun bay doors, the gap cover doors and the
The two center section flaps extend from the side of the fuselage outboard to the wing hinge line. The center section flaps are of aluminum construction. The skin is attached to the ribs, to the hat section splices and to an extruded trailing edge strip by means of rivets and spot welds. The trailing edge strip is made from CVC-1677, and if damaged it must be replaced. At points of maximum stress, the skin is reinforced with "U"-shaped stringers which are flattened out to pass over the ribs. In the right hand center section inboard flap only there is a step installation.
Skin and Stringers: The upper and lower leading edge skins are lapped and spotwelded together at the extreme leading edge. The leading edge skins are also spotwelded to the upper and lower splice plates. Upper and lower trailing edge skins are riveted to the splice plates, ribs and trailing edge strip. The “U” shaped reinforcing stringers are spotwelded to the skin.
Ribs: The center section flap ribs are formed of light gage sheet, with bent up flanges and formed holes. They are riveted to the skin. (Fig 59)
The outer panel flap is constructed of metal skin, stringers, ribs, beam and trailing edge. A diagonal bulkhead attaches to the inboard rib and to the aft face of the main beam web.
Skin and Stringers:
Ribs and Brace Tubes: The outer panel flap contains both leading edge and trailing edge ribs. All of the ribs of the outer panel flap are former ribs, many of them having flanged lightening holes. The leading edge ribs are riveted directly to the beam web, while the trailing edge ribs are attached to vertical stiffeners on the aft face of the beam web. Diagonal brace tubes attach to the trailing edge rib at Station 42 and to the center of
the outboard rib of the flap.
Beam: The outer panel flap beam is constructed of bent up, channel-shaped, thin gage alclad material. Vertical stiffeners reinforce the beam and serve as attaching members for the trailing edge ribs.
Trailing Edge Strip: The trailing edge strip is formed of elliptical shaped alclad tubing. A phenolic filler is inserted into the tubing so that it is possible to rivet the upper and lower skins through the trailing edge strip.
The aileron has an all wood frame assembly with a plywood skin covering. In order to protect the wood from changes in humidity and climate, the aileron is given three dip-coats of wood sealer in production, which seal both inside and outside surfaces. To protect it further, cotton balloon cloth is attached to the plywood skin.
The leading edge, forward of the wood beam, is composed of a series of reinforced ribs and a nose section reinforced with a solid wood nose block. The trailing edge is composed of a series of V-shaped ribs and a trailing edge strip.
Both ailerons have a balance tab that is also constructed of plywood skin, wood ribs, beams and trailing edge strip, and is protected with sealer the same as the ailerons. The plywood skin of the balance tabs is also completely covered with cotton balloon cloth.
The left hand aileron only has a trim tab and is all-wood construction, fabricated and protected the same as the balance tabs. Cotton balloon cloth covers the trim tab.
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