Nose landing gear arrangement with a collapsible support structure designed to minimize the stowed volume of the landing gear

A nose landing gear arrangement including a leg assembly with a pivot axis A at one end thereof and a landing gear wheel mounting at the other end thereof. Two stays are provided, each stay being mounted at one end thereof to the leg assembly and mountable at the other end thereof to an aircraft. Each stay includes an upper stay part and a lower stay part which are hinged together by means of a simple hinge. The upper stay part has a cardan joint at its end spaced from the hinge to enable hinged mounting to an aircraft. The lower stay part has a cardan joint at its lower end spaced from the hinge, the cardan joint of the lower stay part hingedly mounting the lower stay part to the leg assembly. The leg assembly and the stays are arranged so that the stays extend from the leg assembly on opposite sides thereof and the stays fold into a stowed position so that they lie substantially alongside the leg assembly when the leg assembly is retracted.

RELATED APPLICATIONS

The present application is based on, and claims priority from, British Application Number 0900815.2, filed Jan. 20, 2009, the disclosure of which is hereby incorporated by reference herein in its entirety.

FIELD OF THE INVENTION

The invention relates to a nose landing gear arrangement, most particularly for use in aircraft that have a tricycle landing gear arrangement.

BACKGROUND OF THE INVENTION

A nose landing gear of an aircraft is generally stored within a volume within the forward section of the aircraft fuselage so as to reduce aerodynamic effects that might penalise the performance of the aircraft. The area around the nose landing gear is the nose landing gear bay. Also, occupying the available volume within the forward section of the aircraft are electronic assemblies, including avionics, radar equipment, and the flight deck. The shape of the nose fuselage influences the performance of the aircraft. If the volume of equipment required to be stored within the nose fuselage is minimised then there is more flexibility to produce a more efficient shape for that fuselage and improve aircraft performance. Also, the walls of the nose landing gear bay are subject to pressurisation and need to be reinforced to contain that pressure. If the pressurised surface area and nose landing gear bay is reduced, then so is the reinforcement needed and hence the mass of the nose landing gear bay.

Typically nose landing gear will have a leg assembly on which there is a pivot which allows the leg assembly to be rotated and stowed in a nose landing gear bay. To restrain the leg assembly and prevent the nose landing gear assembly from collapsing when the aircraft is on the ground or being pushed back when the aircraft is in the air by aerodynamic forces, conventional nose landing gear commonly have a long stay assembly. The stay assembly is normally attached at one end to the aircraft at a point substantially forward and above the nose landing gear assembly and at the other to a point on the nose landing gear leg. The attachment point of the stay assembly to the aircraft and the attachment point of the stay assembly to a leg, both normally lie on axes that are parallel to the axis of the leg assembly pivot.

The stay assembly normally comprises an upper and lower stay member which can fold about a central hinge. When the leg is deployed, the stay assembly is prevented from folding by a locking arrangement which prevents the nose landing gear from being rotated up inside the nose fuselage.

Typically, in a nose landing gear bay, the upper attachment point of the stay assembly on the aircraft structure and the nose landing gear leg attachment to the aircraft are connected together by a reinforced aircraft structure. If the distance between those two points is large then an unnecessary additional weight is added to the aircraft. Keeping the distance small reduces the weight impact on the aircraft so there will be less additional reinforced aircraft structure.

In a conventional arrangement, when the nose landing gear is rotated up inside the nose fuselage during normal flight, the leg is stowed in the nose fuselage with the stay assembly folded above the leg assembly. This increases the nose landing gear bay volume required due to the additional height required within the nose landing gear bay to enclose the folded stay assembly.

It is an object of the present invention to provide an improved nose landing gear arrangement.

SUMMARY OF THE INVENTION

According to a first aspect of the invention, there is provided a nose landing gear arrangement for an aircraft, the nose landing gear arrangement comprising a leg assembly having a pivot axis at one end thereof and a landing gear wheel mounting at the other end thereof and two stays, each stay being mounted at one end thereof to the leg assembly and being mountable at the other end thereof to an aircraft, each stay comprising an upper stay part and a lower stay part hinged together, the upper stay part having a cardan joint at its end spaced from the hinge to enable hinged mounting to an aircraft and the lower stay part having a cardan joint at its end spaced from the hinge, a cardan joint of the lower stay part hingedly mounting the lower stay part to the leg assembly, the leg assembly and stays being arranged so that the stays extend from the leg assembly on opposite sides thereof and the stays fold into a stowed position so that they lie substantially alongside the leg assembly when the leg assembly is retracted.

In that way, when the nose landing gear is retracted, the stays are arranged on either side of the nose landing gear leg rather than above it. That reduces the required minimum depth of the nose landing gear bay, which, in turn, provides greater flexibility to the aircraft designer in designing the nose fuselage.

According to another aspect of the invention, there is provided an aircraft having a nose landing gear arrangement, the nose landing gear arrangement having a stowed condition in which it is received within a nose landing gear bay and a deployed condition in which it extends out of the bay, the nose landing gear arrangement comprising a leg assembly having a pivot axis at one end thereof and a landing gear wheel mounting at the other end thereof, and two stays, each stay being mounted at one end thereof to the leg assembly and at the other end thereof to the aircraft, each stay comprising an upper stay part and a lower stay part hinged together, the upper stay part having a cardan joint at its end spaced from the hinge to mount the stay to the aircraft and the lower stay part having a cardan joint at its end spaced from the hinge, the cardan joint of the lower stay part hingedly mounting the lower stay part to the leg assembly, the leg assembly and stays being arranged so that the stays extend from the leg assembly on opposite sides thereof when the nose landing gear arrangement is in its deployed condition and the stays fold so as to lie substantially alongside the leg assembly when the nose landing gear arrangement is in its stowed condition.

A nose landing gear arrangement10in accordance with the invention is shown inFIGS. 1 to 4in a deployed condition.

InFIG. 1the nose landing gear arrangement10is shown deployed from a nose landing gear bay12, part of which is cut away for clarity.

The nose landing gear arrangement10comprises a nose landing gear leg14which has a pair of side braces16,18at the upper part thereof. The lower end of the leg14comprises a shock absorber arrangement20of known form. A wheel mounting22is arranged at the bottom of the shock absorber20and the wheel mounting22carries two wheels24,26, one on either side of the leg14.

Each side brace16,18comprises a main side brace arm16a,18awhich extends from a position on the leg14spaced slightly from the top of the leg14. Side brace support arms16b,18brespectively extend from the upper/outer ends of the side brace arms16a,18aand are connected to the nose landing gear leg14at the top thereof. At the point where the side brace arm16ameets the support arm16b, a pivot mounting28is provided. Likewise, where the side brace arm18aand the support arm18bmeet, another pivot mounting30is provided. The pivot mountings28,30mount pivot pins32,34respectively and the pivot arms are coaxial about the axis A.

The pivot pins32,34are, in turn, mounted to the nose landing gear bay to allow the nose landing gear arrangement to pivot about them into the bay12. A lug36projects from an upper part of the leg14forwardly thereof from a point beneath the axis A. The free end of the lug36is connected to one end of an actuator38which is mounted to the aircraft fuselage within the bay12. A set of torque links40extends from the wheel mount22rearwardly thereof for connection to a steering mechanism (not shown).

Two stays42,44extend from a collar at around the mid point of the nose landing gear leg14. The stays42,44, when the nose landing gear is in the deployed condition, are angled respectively to the main side brace arms16a,18a. Each stay42comprises an upper stay part42a,44aand a lower stay part42b,44b. The two parts42a,42b44a,44bare hinged together by means of a simple hinge46. The upper stay parts42a,44aare mounted to and articulated relative to the fuselage by means of cardan joints48. The cardan joints allow the upper parts42a,44ato rotate about two generally perpendicular axes.

The lower end of the lower part42b,44bare connected to the collar46by means of cardan joints48. Again, those cardan joints allow the lower parts to rotate about two generally perpendicular axes.

By mounting the upper and lower parts of the stays42,44to the fuselage and nose landing gear leg with cardan joints, the stays42,44can fold away to either side of the nose landing gear leg when the leg is retracted.

FIGS. 5 to 8illustrate the nose landing gear assembly10in its retracted condition. In order to retract the landing gear the actuator38is actuated to pull the lug36upwardly, in turn causing the nose landing gear leg14to pivot about the axis A upwardly into the nose landing gear bay12. As can be seen most clearly inFIGS. 5,6and8, as the nose landing gear leg14pivots about axis A upwardly into the nose landing gear bay12, the stays42,44rotate about the simple hinge between their respective upper and lower parts42a,44a,42b,44band the cardan joints48allow the stay parts to twist and fold away to either side of the nose landing gear leg14.

In that way, by removing the need to have the folded stay accommodated above the nose landing gear leg14, the overall space taken up by the nose landing gear bay12is minimised.

The design of the stays42,44with the simple hinge in the middle and the cardan joints at either end allows the stay to be provided but at the same time it folds away compactly within the previous envelope defined by the nose landing gear.

Looking atFIG. 8, it can be seen that the lower parts42b,44bof the stays42,44extend adjacent to and substantially along side the side braces16,18. The upper parts lie substantially along side the vertical wall of the nose landing gear bay12, as shown inFIG. 6. By adopting that configuration the stay is provided without the need for additional room within the nose landing gear bay. It is not sufficient to move the problem from one area to another, i.e. from above the retracted nose landing gear leg14to a side thereof. In the present invention, the retracted nose landing gear takes up the same foot print that the retracted landing gear with the traditional stay would have taken up when viewed in plan but when viewed in profile as inFIG. 6, less space is taken. Also, because the stay attachments are arranged close to the surface of the fuselage, the extent of reinforcing structure required is reduced compared to the conventional arrangement, which in turn reduces the weight of the entire nose landing gear arrangement.