Patent Description:
During operation, aircraft face an undesirable risk of ice accretion on forward facing components such as the leading edge of wings, horizontal stabilizers, or other airfoils. Ice that forms on airfoil components can cause drag, loss of lift, and added weight. In order to avoid such problems, it is desired to provide an ice protection system that reduces ice formation on airfoil surfaces while also maintaining relatively low power expenditures by the ice protection system. One such ice protection system is a pneumatic de-icer.

Existing pneumatic de-icers (sometimes called de-icer boots) employ inflation tubes created between an inner layer and an outer layer of the de-icer. The inflation tubes inflate causing portions of the outer layers to move away from the aircraft structure. This movement deforms the outer layer so that ice that has accumulated on the outer layer cracks and is shed from the outer layer.

Pneumatic de-icers on airfoil leading edges horizontal stabilizers of some aircraft are subjected to a high utilization (e.g., inflation/deflation cycle) rate due to system operational designs of multiple inflations per de-icing cycle, as well as increased system utilization mandated for aircraft by aviation authorities due to severe icing events. This increased utilization of the pneumatic ice protection system results in increased fatigue of the de-icers. In some cases, for instance at the horizontal stabilizer location, the increased fatigue results in internal stitchline breakage followed by tearing of the surface plies of the material of the de-icer. In some cases, these tears become a scoop due to the flow of air over the horizontal stabilizer surface. This scoop affects flight quality on aircraft and, in some cases if not managed properly, can become a safety concern.

<CIT> describes a sewn alternate inflate pneumatic de-icer.

<CIT> describes systems and methods for spinning carbon nanotubes into yarn. <CIT> describes a carbon nanotube anti-icing and de-icing means for an aircraft.

Disclosed and defined in claim <NUM> is a de-icing assembly for a surface of an aircraft.

The stitchlines of each seam can span the length of the carcass.

The control unit can be configured to determine a number of inflations of the assembly based on current passing through the single stitchline.

The control unit can be configured to determine that the single stitchline is broken based on current passing through the single stitchline.

A first reinforcement stitchline can be sewn into the carcass adjacent to one of the plurality of seams, wherein the first reinforcement stitchline is disposed at a location on the carcass overlapping with the manifold and wherein the first reinforcement stitchline is disposed approximately perpendicular to the manifold centerline and extends across the width of the manifold.

The assembly can comprise a first reinforcement stitchline sewn into the carcass adjacent to one of the plurality of seams, wherein the first reinforcement stitchline is disposed at a location on the carcass overlapping with the manifold and along an inflation passage fed by the manifold.

A length of the first reinforcement stitchline can be greater than the width of the manifold.

The assembly can further comprise a second reinforcement stitchline sewn into the carcass adjacent to one of the plurality of seams, wherein the second reinforcement stitchline is disposed at a location on the carcass overlapping with the manifold and wherein the second reinforcement stitchline is disposed approximately perpendicular to the manifold centerline and extends across the width of the manifold.

Also disclosed is aircraft that includes an airfoil with a surface and a de-icing assembly of any prior embodiment.

<FIG> is a perspective view of aircraft <NUM> including wings <NUM>, horizontal stabilizers <NUM>, and fuselage <NUM>. Wings <NUM> include leading edges <NUM> and horizontal stabilizers <NUM> include leading edges <NUM>. In the illustrated configuration of <FIG>, aircraft <NUM> is of a fixed-wing design. Fuselage <NUM> extends from nose section <NUM> to tail section <NUM>, with wings <NUM> fixed to fuselage <NUM> between nose section <NUM> and tail section <NUM>. Horizontal stabilizers <NUM> are attached to fuselage <NUM> on tail section <NUM>. Wings <NUM> and horizontal stabilizers <NUM> function to create lift and to prevent pitching, respectively, for aircraft <NUM>. Wings <NUM> and horizontal stabilizers <NUM> include critical suction surfaces, such as upper surfaces <NUM> of wings <NUM> and lower surfaces <NUM> of horizontal stabilizers <NUM>, where flow separation and loss of lift can occur if icing conditions form on any of the surfaces of wings <NUM> and horizontal stabilizers <NUM>. <FIG> also shows de-icing assemblies <NUM> mounted onto leading edges <NUM> of wings <NUM> and onto leading edges <NUM> of horizontal stabilizers <NUM>. In other non-limiting embodiments, de-icing assemblies <NUM> can be mounted onto any leading edge or non-leading edge surface of aircraft <NUM>. De-icing assemblies <NUM> function by filling with air to deform an outward surface of de-icing assemblies <NUM> so as to break apart ice formed on horizontal stabilizers. Further, it should be noted that the assemblies could be mounted to an engine lip and engine induction deicers generally shown by reference number <NUM>.

<FIG> shows a top view of de-icing assembly <NUM> with manifold <NUM> (including air connection holes <NUM> and manifold centerline CLM) and de-icer <NUM> (including carcass <NUM> with boundary <NUM>, carcass centerline CLC, seams <NUM> a-<NUM> e, first stitchlines <NUM> a-<NUM> e, second stitchlines <NUM> a-<NUM> e, first reinforcement stitchlines <NUM> a-<NUM> e, second reinforcement stitchline <NUM> c, and inflation passages <NUM>). <FIG> also shows length LC of carcass <NUM>. <FIG> is a cut-out detail view of de-icing assembly <NUM> and manifold <NUM>. <FIG> also shows width WM of manifold <NUM> and length LRS of first reinforcement stitchlines <NUM> b-<NUM> d and second reinforcement stitchline <NUM> c. <FIG> and <FIG> show substantially similar views, and will be discussed in unison.

Herein, the stitches of any of first and second stitches <NUM>, <NUM>, can be formed of a carbon nanotube (CNT) yarn. The same CNT yarn can also be used in reinforcing stitch lines <NUM>, <NUM>. In prior systems, the first stitchlines <NUM> a-<NUM> e, second stitchlines <NUM> a-<NUM> e, first reinforcement stitchlines <NUM> a-<NUM> e, and second reinforcement stitchline <NUM> c are loops of thread formed of para-aramid synthetic fiber, aramid polymer, aliphatic polyamide, semi-aromatic polyamide, or another type of synthetic polymer or polyamide. Inflation passages <NUM> are inflatable tubes or channels.

Further, as shown in <FIG>, due to CNT yarn being stronger that prior art stitch materials, the need for two separate stich lines can be reduced and only a single stitch line <NUM> a-b may be needed. In <FIG>, while the reinforcement stitchlines <NUM>, <NUM> are shown, they can be optional and one or both can be omitted. Further, <FIG> that a combination of single stitch lines <NUM> can be included with double stitchlines. Of course, only single stitchlines could be realized and <FIG> is not meant to require a combination.

In both <FIG> and <FIG>, the de-icing assembly <NUM> is an assembly of components configured to remove ice formed on de-icing assembly <NUM>. Manifold <NUM> is a conduit for the transmission of a fluid such as a gas. Air connection holes <NUM> are orifices configured to allow passage of a fluid such as a gas. Width WM is a width of manifold <NUM> measured from left to right in <FIG> and <FIG>. In one non-limiting embodiment, width WM can be approximately <NUM> inches (<NUM> centimeters). Manifold centerline CLM is an imaginary line passing through a center of manifold <NUM>. Deicer <NUM> is an element configured to remove ice formed on de-icing assembly <NUM>. In one non-limiting embodiment, de-icer <NUM> can include a pneumatic de-icer. Carcass <NUM> is a flexible, layered article configured to retain a volume of pressurized gas. Boundaries <NUM> are edges or borders of carcass <NUM>. Carcass centerline CLc is an imaginary line passing through a center of carcass <NUM>.

Seams <NUM> a-<NUM> e are lines along which layers of carcass <NUM> are joined and/or attached together. In one non-limiting embodiment, any of seams <NUM> a-<NUM> e can include one or more stitchlines such as described above. In one non-limiting embodiment, passages <NUM> can include a width (measured from top to bottom in <FIG> and <FIG>) of <NUM> inch (<NUM> centimeters) between adjacent seams <NUM> a-<NUM> e. In another non-limiting embodiment, passages <NUM> on either side of carcass centerline CLC can include a width of <NUM> inches (<NUM> centimeters). Length LC is a length of carcass <NUM> (measured from left to right in <FIG> and <FIG>).

In operation, the de-icing assembly <NUM> is attached to or mounted to a surface of aircraft <NUM> such as one or both of horizontal stabilizers <NUM> (as shown in <FIG>). Manifold <NUM> is fluidly connected to de-icer <NUM> and is disposed beneath carcass <NUM>. Air connection holes <NUM> are fluidly connected to inflation passages <NUM> of carcass <NUM> and to an air supply (not shown) located on aircraft <NUM>. Manifold centerline CLM extends longitudinally across manifold <NUM> and approximately bi-sects manifold <NUM> into halves approximately of equal size. Manifold centerline CLM is oriented approximately perpendicular to carcass centerline CLC. De-icer <NUM> is fluidly connected to manifold <NUM>. Carcass <NUM> is disposed above and fluidly connected to manifold <NUM>. Boundaries <NUM> extend around a perimeter of carcass <NUM>. Carcass centerline CLc extends longitudinally across (from left to right in <FIG> and <FIG>) carcass <NUM> and approximately bi-sects carcass <NUM> into two sections sized as necessary for the particular airfoil.

Seams <NUM> a-<NUM> e extend longitudinally across carcass <NUM>. Seams <NUM> a-<NUM> e form channels <NUM> between consecutive seams <NUM> a-<NUM> e. First stitchlines <NUM> a-<NUM> e, second stitchlines <NUM> a-<NUM> e (<FIG>) or single stitchlines are sewn (e.g., stitched) into and through the layers of carcass <NUM> to attach the layers of carcass <NUM> together. If present, first reinforcement stitchlines <NUM> a-<NUM> e, and second reinforcement stitchline <NUM> c are also so sewn.

In some non-limiting embodiments, first reinforcement stitchlines <NUM> a-<NUM> e can be disposed on an opposite side of respective seams <NUM> a-<NUM> e from carcass centerline CLC. In other non-limiting embodiments, first reinforcement stitchlines <NUM> a-<NUM> e can be disposed on a same side of respective seams <NUM> a-<NUM> e as carcass centerline CLC. In some non-limiting embodiments, second stitchlines <NUM> a-<NUM> e can be disposed on an opposite side of respective seams <NUM> a-<NUM> e from carcass centerline CLc. In other non-limiting embodiments, second stitchlines <NUM> a-<NUM> e can be disposed on a same side of respective seams <NUM> a-<NUM> e as carcass centerline CLc. Inflation passages <NUM> are formed by and extend between seams <NUM> a-<NUM> e. Inflation passages <NUM> are disposed between the layers of carcass <NUM>. Length LC extends across (from left to right in <FIG> and <FIG>) a length of carcass <NUM> in a direction approximately perpendicular to manifold centerline CLM.

Pneumatic de-icing systems and functioning thereof are described in <CIT> and in <CIT>, both of which are incorporated herein by reference in their entireties.

During operation of aircraft <NUM> in icing conditions, passages <NUM> of deicer <NUM> are subjected to inflation and deflation during de-icing cycles of de-icer <NUM>. As de-icer <NUM> performs de-icing cycles, the inflation and deflation of passages <NUM> causes fatigue in the layers of carcass <NUM>. During normal operation of de-icer <NUM>, second stitchlines <NUM> a-<NUM> f distribute the stress along seams <NUM> a-<NUM> e, respectively across two stitchline lines instead of just one. This effectively reduces the amount of stress experienced per stitch by <NUM>% as compared to a configuration with only a single stitchline.

<FIG> shows a perspective view of de-icer <NUM> in a distended (e.g., inflated) condition and includes horizontal stabilizer <NUM>, carcass <NUM>, carcass centerline CLC, seams <NUM> a-<NUM> e, first stitchlines <NUM> a-<NUM> e, second stitchlines <NUM> a-<NUM> e, first reinforcement stitchlines <NUM> a-<NUM> e, second reinforcement stitchline <NUM> c, inflation passages <NUM>, first layer <NUM> of carcass <NUM>, second layer <NUM> of carcass <NUM>, ice <NUM>, and tensile stresses <NUM>. Manifold <NUM> is omitted from <FIG> for clarity.

The view of <FIG> shows carcass <NUM> in a distended, or inflated, state illustrating breakage of ice as well as the stress experienced by first and second layers <NUM> and <NUM> of carcass <NUM>. As carcass <NUM> is inflated, first layer <NUM> pulls away from second layer <NUM> forming a curved shape. As first layer <NUM> pulls away from second layer <NUM>, stress is placed on both first layer <NUM> and on second layer <NUM> in the form of tensile stress <NUM> and other forms of stress such as hoop stress. Tensile stress <NUM> and other forms of stress experienced by both first and second layers <NUM> and <NUM> of carcass <NUM> can lead to failure events related to the stitchlines.

<FIG> further shows how single stitchline <NUM> in combination with or without first reinforcement stitchlines <NUM> a-<NUM> e, and second reinforcement stitchline <NUM> c (e.g., stitchlines <NUM> and <NUM> are optional) help to distribute the stresses experience by de-icer <NUM> (such as tensile stresses <NUM>) across multiple stitchlines helping to minimize the initiation of stitchline breakage, minimize the propagation rate of a stitchline break, stop the propagation of a stitchline break, and stop the propagation of a rupture of either first layer <NUM> or second layer <NUM> of carcass <NUM>.

With reference to <FIG> and <FIG>, it is noted, however, that the CNT fibers of the single stitch lines <NUM> can have the same effect at the first and second stitchlines in combination and, thus, reduce the amount of stitching needed. Further, due to the smaller sized of CNT yarn as compared to the prior art it can bonds to other layers in the system. Further, overtime the CNT yarn does not retain water and may last longer.

For the sake of completeness, it is noted that a CNT yarn is a fiber formed of carbon nanotubes wound together. The CNT's can be cylinders of one or more layers of graphene (lattice). Such a yarn can be formed such that is electrically conductive in one embodiment and as more fully described below.

This electrically conductive nature of the CNT yarn can allow for the yarns to be used for other purposes as well. Firstly, and with reference to <FIG>, a control element <NUM> can be provided that is electrically connected to the single stitchlines 45a, 45b. The control element <NUM> can provide a current to the single stitchlines 45a, 45b in one embodiment. When provided, if the current is not as expected, that can indicate that the single stitchlines 45a, 45b has broken. Further, to that end, as part of the controller <NUM> as a separate element <NUM> as illustrated, the current can be sensed by a sensor <NUM>. The sensor <NUM> could, for example, determine variations in current received that could indicate a change in resistance in the stitchlines 45a, 45b. This indication could be used by the control unit <NUM> to count how often the deicer has to be cycled and could be used to plan inspection or servicing of the deicer.

Claim 1:
A de-icing assembly for a surface of an aircraft, the de-icing assembly comprising:
a carcass (<NUM>) with a first layer, a second layer, and a carcass centerline (CLC);
a plurality of seams (<NUM>) sewn into the carcass (<NUM>), wherein the plurality of seams (<NUM>) join the first and second layers of the carcass (<NUM>) together;
a plurality of inflation passages (<NUM>) formed by the plurality of seams (<NUM>) and disposed between the first and second layers of the carcass (<NUM>);
a manifold fluidly connected to and disposed beneath the carcass (<NUM>), the manifold comprising a width and a manifold centerline (CLM) oriented approximately perpendicular or parallel to the carcass centerline; and characterized in that
the seams (<NUM>) are sown by a stitchline formed of carbon nanotube yarn,
wherein each seam of the plurality of seams (<NUM>) comprises includes a single stitchline;
the assembly further comprising a control unit that provides an electrical current to the single stitchline.