The Boeing Company

John A Stepien

Robert B Brown

Milton E James

A hydraulic control cylinder (64) is used to swing the upper part (14) of a two part wheel strut (14, 16) about an axis of rotation (18) established at the upper end of the upper strut part (14) and at an upper central location within a stowage compartment (10). A folding drag brace assembly (102) is connected between the strut (16) and a lower rear portion of the stowage compartment (10). During use of the control cylinder (64) for swinging the upper strut part (14) rearwardly and upwardly, the drag brace (102) folds automatically in the manner of a pantographic device, and functions to fold the lower strut part (16) up against the upper strut part (14) within the stowage compartment (10). A mechanism is provided for rotating the wheel assembly (30) W, relative to the lower strut part (16), for the purpose of properly positioning the wheel assembly (30) W for movement into the stowage compartment (10). The invention makes it possible to retract the landing gear assembly (12) into a stowage compartment (10) which is considerably shorter than the in use length of the landing gear strut (14, 16) without the need for a second 'down lock' member.

Main landing gear with variable length drag brace

A body-braced main landing gear assembly for a commercial airplane includes a set of landing wheels journalled to a shock absorber strut. The shock strut and wheels are swingably attached to the underside of the wing structure by a trunion shaft for lateral as well as fore and aft swinging movement between an extended position wherein the wheels depend downwardly from the wing for taxiing and landing of the airplane and a retracted position wherein the wheels and shock strut are swung inwardly and upwardly into a wheel bay in the airplane fuselage. The shock strut is braced in the extended position by a foldable drag strut and a rigid radius brace. The foldable drag strut is attached at one end to the shock strut and is attached at its opposite end to the fuselage body at a point inward and forward of the trunion shaft. The radius brace is attached at one end to the shock strut and is attached at its opposite end to a point on the fuselage body inward and rearward of the trunion shaft. The body-braced main landing gear assembly permits the landing wheels to be positiond farther aft and farther outboard than normal, resulting in improved airplane ground stability and ground flotation and also in improved airplane aerodynamic performance during flight. The improvement in load path geometry enables a substantial reduction to be made in airplane wing and aft body weights.

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Renton, WA, United States of America

John A Stepien