Concorde Elevons and Rudders

Concorde is controlled in pitch and roll by 6 elevons, and in yaw by 2 rudders. The pilots control column movements are the same for Concorde as in any other aircraft. Unlike other aircraft Concorde has no tail-plane and the elevons are placed along the trailing edge of the wing. The nose up and down movements, are controlled by these 6 elevons (mainly the inner pair). The middle and outer elevons pairs also act as ailerons. This section covers the construction and operation of Concorde’s rudders and elevons

THE ELEVONS

Three elevons are hinged to the trailing edge of each mainplane and are operated by PFCUs mounted on the mainplane lower surface.

ELEVONS – DESCRIPTION AND OPERATION



The elevens are hinged to the trailing edge to form a continuation of the wing aerofoil section. Each wing has three pairs of elevons, outer, centre and inner, which are numbered individually on each side from 1 to 6, outboard to inboard.

The Structure

The elevons are rectangular in plan, except No.1 elevon which tapers from the rear toward the wing tip. The construction is a honeycomb core sandwiched between top and bottom skin panels, enclosed by a front spar, two end ribs and a trailing edge member. Tapered fairings, secured by screws to brackets which are in turn attached either to elevon operating arms or the end ribs, enclose the power flying control unit (PFCU) linkage. There are two types of spar, on elevons 1, 2 and 3 the spars are fully machined and on elevons 4, 5 and 6 the spars are constructed from machined ribs mounted on two ‘T’ plates.

The end ribs are of two types of construction.  Those in line with wing ribs 6, 12, 21 and 27 are of sheet metal and honeycomb fabrication, white those in line with wing ribs 3, 9 and 24 are fully machined. Both types are sandwiched between the elevon skins and secured by adhesive and rivets. In addition, No.1 elevon outboard rib is also fully machined, with a tip riveted to it.

The trailing edge member of No.1 elevon is fully machined, the other elevons have trailing edges built up from a honeycomb core sandwiched and secured between sheet metal skins by adhesive and rivets.

The trailing edge of each elevon is extended by 2 inches, the extension consisting of metal sheet formed into a V-section and secured by adhesive and rivets to the trailing edge. Brackets betted to the original trailing edge extend the static discharge wick mountings to the new trailing edge position. Removable leading edges are attached to the front spar by screws.


Hinges and Attachments

Each eleven has two hinge bearings and a control bearing. The control bearing and one of the hinge bearings are in the same vertical plane and fitting. This fitting is attached to the fully machined end ribs. The independent hinge bearings are secured to the front spar in line with wing ribs O, 6, 12, 21 and 27.

Each pair of elevons is operated by a PFCU, one being mounted at each of wing ribs 3, 9 and 24. PFCU movement is transmitted to a pair of elevons by operating rods, one to each elevon. If an operating rod fails, movement is then transmitted to its associated elevon from the other elevon of the pair, by a swing link connecting the two elevens.

The PFCU attached to the elevon on G-BOAC

THE RUDDERS

The upper and lower rudders are each hinged to the aircraft fin torsion box at four points and each incorporates a PFCU arm, which is coupled to the jack mechanism in the torsion box and is covered by a fairing.

RUDDERS – DESCRIPTION AND OPERATION



There are two rudders fitted to Concorde, Known as the  upper and lower rudders, each is attached to the rear spar of the vertical stabilizer (Fin) torsion box by four hinges; the hinges are numbered 1 to 8 from the bottom of the lower rudder to the top of the upper one. Each rudder has two slinging points built into its top rib, this allows it to be removed and replaced independently. The top rib of the upper rudder has a glass-fibre fairing.

Each of the rudder upper and lower sections are composed of a honeycomb core, clad on both sides by an etched skin and bounded at the front by a spar to which the nose structure is bolted, and at the rear by a trailing edge member.

The two honeycomb core sections in each rudder are separated by a power flying control unit (PFCU) arm. They are enclosed at the top and bottom ends of the lower rudder and at the bottom end of the top rudder by ribs and at the top of the upper rudder by a failring. There is a spherical bearing at the forward outer end of the PFCU arm which is connected by a rod to the associated PFCU jack on the vertical stabilizer torsion box.

The skin gaps are closed by a PFCU fairing on one side and a joint plate on the other side, drain holes are provided to prevent the collection of water.

Leading Edge

The leading edge is formed by nose ribs and a nose skin the ribs being machined diaphragms, with double flanges at their outer edges, which are attached to the spar. The ribs are numbered from the bottom, from 4 to 13 on the bottom rudder and 2 to 14 on the upper rudder. The nose skin consists of eight removable sections, betted to the spar and to the flanges of the nose ribs, with small detachable plates giving access to the hinges.

Trailing Edge

The training edge consists of a formed trailing edge member, bonded to the rear of the structure. The trailing edge of each rudder is extended by 2 inches, the  extension consisting metal sheet formed into a V-section and secured by adhesive and rivets to the trailing edge between the static discharge wick mountings

Hinges

The lower PFCU arm hinge (No.3) is the datum hinge for the lower rudder and consists of a single bracket, which is bolted to the PFCU arm with an integral lug carrying the hinge bolt spherical bearing.

The upper PFCU arm hinge (No.6) is the datum hinge for the upper rudder and consists of two separate brackets, one above the other, bolted to the PFCU arm, with an integral lug carrying a hinge bolt spherical bearing. All the other hinges consist of single brackets bolted to the spar flange, with links bolted to them carrying the hinge bolt spherical bearings. The links of hinges 1, 2, 4 and 5 are secured to their brackets by bolts in spherical bearings, whilst those of hinges 7 and 8 have swivel bolts.

The Honeycomb Core

The honeycomb core of each rudder section is bonded to the front spar, the PFCU arm, the trailing edge member, the ribs and the skins by an adhesive. Each section is sealed against the ingress of water.

PFCU Arms

One PFCU arm is on the left side of the lower rudder and the other on the right side of the upper one, at hinge positions 3 and 6, respectively. Each arm forms the closing rib between the upper and lower sections of the rudder, to which it is riveted and bonded, and each carries a spherical bearing at its forward outer end, this is for attachment of the rod from the PFCU jack in the vertical stabilizer (Fin) torsion box.

The outboard PFCU arm plate, which is on the same side as the fairing, has 0.75 (19.05 mm) dia. inspection holes, five on the upper and seven on the lower plate.

PFCU Fairings

The PFCU fairings are on the left side of the lower rudder, and on the right side of the upper. Each set of fairings comprises a forward fairing and an aft fairing. Each consists of a honeycomb core between skins, the lower fairing being stiffened by diaphragms and the upper by ribs.

The fairing attachment is the same for both the upper and lower rudders. The front of the forward fairing is attached to the PFCU arm by two split-pinned bolts and nuts and the rear by spigots and self-aligning bearings.

The front of the aft fairing is attached to the arm by similar spigots and self-aligning bearings and the rear by six bolts, to a hinged bracket on the rudder structure. These attachments allow the sections to move relative to each other, to provide for thermal expansion and flexing, seats are fitted round the edges of both the fairings.

Fail-Safe Devices

The datum hinge for the lower rudder is No.3 and for the upper rudder, No.6. A safety device at No.1 hinge ensures that if the lower rudder datum hinge should be damaged, the vertical loads would be carried by No.1 hinge. On the upper rudder, No.6 hinge is duplicated and either part is able to carry the vertical loads, independently, if the other half should fail.

FOR FURTHER READING REGARDING THE FLYING CONTROLS

CLICK ON THE LINKS BELOW

General Description of the Control Surfaces

Power Flying Control Unit (PFCU)

Roll, Pitch & Yaw

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