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AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorWilliam R. Pinnell
Estimating the term…
A frameless aircraft cockpit enclosure comprising transparent panels of polycarbonate or other plastics of varying thickness and material properties. The edges of the transparent panels are made thicker than the rest of the panels to engage aircraft canopy and windshield arch sections and aircraft sill structures to thus eliminate prior art frames and edge reinforcements. Fibers may be embedded in the thicker edges to add strength. The material properties of the transparent panel may be varied to provide higher static load strength near aircraft sill structures and higher dynamic load strength and plastic behavior near the center of a canopy where bird impact may occur. The material properties of the panel may also be varied to minimize over a pilot's head or near aircraft critical equipment the amplitude of a flexure wave in an aircraft transparency resulting from a bird impact. Direct forming methods, such as injection molding, are discussed as a means for making the frameless aircraft transparencies.
A cockpit enclosure for an aircraft having a cockpit sill structure, comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
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The present invention relates generally to aircraft transparencies, or windshields and canopies, and more particularly to frameless transparencies.
Transparent cockpit enclosures for fighter and trainer type high performance aircraft typically comprise a plurality of aircraft transparencies. The transparencies comprise curved transparent panels surrounded by frames providing both structural support and means for attaching the transparencies to aircraft sill structures. The frames are usually fabricated of metal or a matrix of high strength fibers, and are attached to the transparent panels by bonding agents or fasteners.
Large discontinuities in material properties exist at the panel and frame boundaries, creating design complications for structurally withstanding the dynamic loading associated with bird impact. Rows of bolt holes near transparent panel edges in most transparancies weaken the panels in that critical structural area. The panel and frame design requices pressure seals at both the panel and frame interface and at the frame and aircraft sill structure interface. Stresses occur in the transparent panels due to frame installation and differential thermal expansion. These stresses lead to structural deficiencies, optical distortions and limited durability. The frames themselves are generally made of metals such as magnesium, having high static strength, but brittle in response to dynamic loads such as bird strikes.
The present invention will be more clearly understood from a reading of the following detailed description in conjunction with the accompanying drawings wherein:
FIG. 1 is a perspective view of a prior art transparency windshield and canopies.
FIG. 2 is a cross-sectional view along line B--B of FIG. 1 of a prior art transparency windshield arch section.
Referring now to FIG. 1 of the drawings, there is shown a perspective view of a prior art transparency windshield and canopies. The transparency comprises a windshield 2 and two canopy sections 4 and 6 mounted on an aircraft 8. The windshield 2 and the canopies 4 and 6 meet at arch sections 10, 12, and 14. The windshield 2 and the canopies 4 and 6 meet the aircraft 8 at the sill sections 16, 18 and 20 through frames 22, 24 and 26 which surround transparent panels 28. 30 and 32. Canopies 4 and 6 are hinged at the rear through hinges 5 and 7 to allow pilot or aircrew member ingress and egress. Other designs provide hinges along the canopy frame sides. Additionally, many rear hinged designs include hinges along the frame sides to minimize bending moments that might otherwise be transmitted to relatively brittle acrylic transparency panels from the aircraft sill structure.
FIG. 2 is a cross-sectional view along line B--B of FIG. 1 of a prior art transparency windshield arch comprising a transparent panel 30 attached to a metal frame 34 by bolts 36 or rivets through rows of holes drilled in the transparent panel 30. Elastomeric sealing strips 38 and 39 are used to provide a positive pressure seal between transparent panel and frame.
FIG. 3 is a cross-sectional view along line C--C of FIG. 1 of a prior art transparency windshield sill section comprising a transparent panel 28, edge reinforcement 38, a fairing 40, and a metal frame 42. A hinge 44 connects the frame 42 to the aircraft sill structure 46. The hinge 44, working in conjunction with an inflatable elastomeric seal 48, provides the necessary flexibility to the windshield aircraft connection to prevent cracking of brittle prior art acrylic windshields.