Metal working – Method of mechanical manufacture – Multiperforated metal article making
Reexamination Certificate
1997-01-07
2001-03-20
Hughes, S. Thomas (Department: 3726)
Metal working
Method of mechanical manufacture
Multiperforated metal article making
C029S017200, C029S558000, C029S424000, C204S192320, C204S192350
Reexamination Certificate
active
06202304
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to laminar flow wings and deicing devices for aircraft, and relates more particularly to a movable sheet that serves as a renewable, laminar flow suction surface, and alternatively as an integral, retractable shield for protecting a suction support structure of a wing against contamination, and that also serves as a movable, conductive substrate for deicing by means of electrical resistance or hot-gas heating and substrate movement. Furthermore, the movable sheet serves to protect the wing surface from debris impact damage and corrosion.
2. Description of the Relevant Art
Laminar flow wings have been proposed in order to reduce drag in aircraft. Laminar flow concepts include shaping the airfoil to enhance laminar flow for small wings, and active measures such as boundary layer suction for larger wings. Promoting laminar flow through suction operates on the principle of removing low energy air from the boundary layer to delay the transition from laminar to turbulent or separated flow.
A suction device for a laminar flow wing typically has a suction support structure comprising a perforated, slotted, or otherwise porous skin on the upper and/or lower surface of the wing. Boundary layer air is sucked through the suction support structure and into a vacuum plenum or manifold located within the wing. A problem that arises with such a suction device is that insects, airborne debris and ice can clog the perforations or slots in the suction support structure and thereby degrade the performance of the suction device. This problem is of concern at low and medium altitudes. Prior to the present invention, large laminar flow wings have been impractical for commercial use in part because of the difficulty in keeping clear the tiny perforations.
Another design consideration for aircraft is the need to prevent ice from accumulating on a wing. Deicing concepts include using chemicals to retard ice formation, using an inflatable or deformable wing surface to break the ice, and heating the wing surface to melt the ice and/or the interface between the ice and the wing. Presently, the chemicals used for wing deicing are toxic and cause great environmental damage. Wing heating requires large amounts of energy, and is heavy and costly. The present invention alleviates these problems.
SUMMARY OF THE INVENTION
In accordance with the illustrated preferred embodiment, the present invention improves upon prior laminar flow wing designs by providing a means for a renewable and cleanable-in-flight laminar flow suction surface and means for shielding a suction support structure against contamination from insects, ice, sand, and other airborne debris. The present invention further provides a means for deicing a wing surface through a combination of electrical resistance or hot-gas heating and physical movement to melt and dislodge accumulated ice.
The present invention is a movable sheet apparatus that has multiple applications—as a movable and retractable laminar flow surface, as a retractable shield for a laminar flow wing porous support structure, as a movable heated deicing element, as a mechanical motion ice remover, and as a replaceable wing protector. In most cases, the invention includes a movable sheet that is mounted scroll-like on two motor-driven rollers mounted within the wing. A portion of the movable sheet is exposed to the airstream passing over the wing, and it is that exposed portion of the movable sheet that interacts with the airstream and either provides laminar flow for the wing or provides the means for protecting the wing and removing ice.
As a perforated or porous primary laminar flow surface, as a movable, self-heating, electrically-conductive substrate for deicing, and alternatively as a retractable shield for a laminar flow wing, the present invention includes a movable sheet mounted like a scroll on two motor-driven rollers and positioned over a suction support structure of the wing. The movable sheet can be positioned to cover the suction support structure to shield it from airborne debris or to uncover the suction support structure to allow boundary layer suction through a perforated or porous portion of the movable sheet. The rollers are rotatably mounted within the wing and extend spanwise with respect to the wing, with one roller mounted forward of the suction support structure and the other roller mounted aft of the suction support structure. The sheet overlies the suction support structure and extends scroll-like between the two rollers, with opposite ends of the sheet engaging the rollers. In one of the preferred embodiments, the sheet has a solid area and a porous area that is permeable to air flowing therethrough. The motor-driven rollers scroll the attached sheet across the suction support structure.
A vacuum source sucks air through the suction support structure when the sheet is positioned with the porous area overlying the suction support structure. In that position, the perforations or porosity of the sheet align with the underlying perforations in the suction support structure. Air is sucked from the boundary layer by the vacuum supply to improve laminar flow characteristics. During takeoff and landing, when contamination by dust, sand, leaves, insects, ice, or other debris is most likely to happen, the sheet can be repositioned so that the solid area of the sheet overlies the suction support structure and protects it from contamination, and so that the porous area of the sheet is wound on a roller inside the wing and is protected from clogging. The solid portion of the movable sheet serves as a wing protector to protect the underlying structure. Extra sheet material can be wrapped onto the rollers so that if one area of the movable sheet becomes worn, damaged, contaminated or otherwise made inoperative, another area can be scrolled into place, thereby providing a renewable surface. The porosity of the porous area can be provided by perforations or by a material, such as a woven or composite material that is inherently porous. As an alternative, the movable sheet can have a sintered layer the overlies the perforated metal sheet. As another alternative, the movable sheet can have large cutout areas that are positioned to expose the underlying suction support structure when laminar flow is desired.
As a movable heating element for a deicer, the present invention includes a movable sheet mounted like a scroll on two motor-driven rollers and means for supplying electric power to resistively heat or supplying hot gasses to thermally heat the sheet. Electrical contact is preferably made at the edges of the sheet through contact rollers. The edges of the sheet are preferably coated with gold, copper, or other high-conductivity metal, alloy, or combination of metals to make good contact with the contact rollers. Electric power is supplied to the contact rollers and thus to the movable sheet, which resistively heats sufficiently to melt the interface between the sheet and any accumulated ice. In addition, the movable sheet can be moved by the motor-driven rollers or an inflatable bladder to dislodge the ice from the wing as a mechanical motion ice remover. Alternatively, hot engine gases are blown through the movable sheet to melt accumulated ice.
The features and advantages described in the specification are not all inclusive, and particularly, many additional features and advantages will be apparent to one of ordinary skill in the art in view of the drawings, specification and claims hereof. Moreover, it should be noted that the language used in the specification has been principally selected for readability and instructional purposes, and may not have been selected to delineate or circumscribe the inventive subject matter. For example, the term “suction support structure” as applied to a wing means any structure through which air can flow, regardless of whether the wing surface has holes, slots, pores, perforations, or other feature that is permeable to air flow therethrough. Furthe
Butler Marc W.
Hughes S. Thomas
Limbach & Limbach LLP
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