阅读说明：本技术 用于飞行器的可去除机身护罩 (Removable fuselage shroud for aircraft ) 是由 D·W·克拉尔 N·J·卡雷 D·D·沃德 B·W·米勒 于 2020-10-15 设计创作，主要内容包括：提供一种限定纵向方向和横向方向的飞行器。该飞行器包括：机身；发动机,该发动机安装在与飞行器的机身间隔的位置处,该发动机包括转子叶片；以及至少一个机身护罩,该至少一个机身护罩在沿横向方向与转子叶片对准的位置处可去除地联接到机身。(An aircraft is provided that defines a longitudinal direction and a transverse direction. The aircraft comprises: a body; an engine mounted at a location spaced from a fuselage of the aircraft, the engine including rotor blades; and at least one fuselage shroud removably coupled to the fuselage at a location aligned with the rotor blades in the lateral direction.)

1. An aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising:

a body;

an engine mounted at a location spaced from a fuselage of the aircraft, the engine including rotor blades; and

at least one fuselage shroud removably coupled to the fuselage at a location aligned with the rotor blades in the lateral direction.

2. The aircraft of claim 1, wherein the at least one fuselage shroud is removably coupled to the fuselage using a plurality of mechanical fasteners.

3. The aircraft of claim 1, wherein the at least one fuselage shroud defines a perimeter, and wherein the at least one fuselage shroud is removably coupled to the fuselage with a plurality of fasteners arranged at a density of at least one fastener per inch and up to 25 fasteners per inch.

4. The aircraft of claim 1 wherein the at least one fuselage shroud defines a forward end and an aft end, wherein the forward end defines a forward end cone angle of at least 1 degree and up to 15 degrees.

5. The aircraft of claim 4 wherein a nose taper angle of the nose is less than or equal to 7 degrees.

6. The aircraft of claim 4 wherein the aft end defines an aft end cone angle of at least 1 degree and up to 15 degrees.

7. The aircraft of claim 1 wherein the at least one fuselage shroud comprises a first layer and a second layer.

8. The aircraft of claim 7, wherein the second layer is hermetically sealed within an interior of the at least one fuselage shroud.

9. The aircraft of claim 8, wherein the at least one fuselage shroud is removably coupled to the fuselage through the first layer.

10. The aircraft of claim 8 wherein the first layer is an energy distribution layer and wherein the second layer is an energy absorption layer.

Technical Field

This application relates generally to armor for the fuselage of an aircraft and to aircraft including the same.

Background

Traditionally, gas turbine engines used in aircraft (e.g., turboprop, unducted, or ducted fan engines) generally include a turbine and a rotor assembly, and a nacelle that surrounds the rotor assembly (also referred to as a fan assembly). The turbine generally includes a high-pressure spool and a low-speed spool. The combustion section receives pressurized air that is mixed with fuel and combusted in the combustion chamber to generate combustion gases. The combustion gases are first provided to the high-pressure turbine of the high-pressure spool, driving the high-pressure spool, and then to the low-speed turbine of the low-speed spool, driving the low-speed spool. The rotor assembly is typically coupled to and driven by the low speed rotating shaft.

Blade loss can cause damage to the aircraft, especially in the case where the rotor of the engine is not enclosed within the nacelle or fan duct, which may at least partially contain the thrown blades.

Disclosure of Invention

Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.

In one aspect of the present disclosure, an aircraft defining a longitudinal direction and a lateral direction is provided. The aircraft comprises: a body; an engine mounted at a location spaced from a fuselage of the aircraft, the engine including rotor blades; and at least one fuselage shroud removably coupled to the fuselage at a location aligned with the rotor blades in the lateral direction.

Technical solution 1. an aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising:

a body;

an engine mounted at a location spaced from a fuselage of the aircraft, the engine including rotor blades; and

at least one fuselage shroud removably coupled to the fuselage at a location aligned with the rotor blades in the lateral direction.

The aircraft of any preceding claim, wherein the at least one fuselage shroud is removably coupled to the fuselage using a plurality of mechanical fasteners.

The aircraft of any preceding claim, wherein the at least one fuselage shroud defines a perimeter, and wherein the at least one fuselage shroud is removably coupled to the fuselage with a plurality of fasteners arranged at a density of at least one fastener per inch and up to 25 fasteners per inch.

Solution 4. the aircraft of any preceding solution, wherein the at least one fuselage shroud defines a forward end and an aft end, wherein the forward end defines a forward end taper angle of at least 1 degree and up to 15 degrees.

Technical solution 5 the aircraft of any preceding technical solution, wherein a nose cone angle of the nose is less than or equal to 7 degrees.

Solution 6 the aircraft of any preceding solution, wherein the aft end defines an aft end cone angle of at least 1 degree and up to 15 degrees.

Solution 7 the aircraft of any preceding solution, wherein the at least one fuselage shroud comprises a first layer and a second layer.

The aircraft of any preceding claim, wherein the second layer is hermetically sealed within an interior of the at least one fuselage shroud.

Solution 9 the aircraft of any preceding solution, wherein the at least one fuselage shroud is removably coupled to the fuselage through the first layer.

Solution 10 the aircraft of any preceding solution, wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer.

Solution 11 the aircraft of any preceding solution, wherein the engine is a single unducted rotor engine, wherein the rotor blades are part of an unducted rotor assembly and are configured as a single-stage unducted rotor blade.

Solution 12 the aircraft of any preceding solution, wherein the fuselage shroud defines a surface area between 720 square inches and 15,000 square inches.

Solution 13 the aircraft of any preceding solution, wherein the fuselage shroud assembly defines a top end and a bottom end in a vertical direction of the aircraft, wherein the fuselage shroud defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

Solution 14. the aircraft of any preceding solution, wherein the aircraft is a narrow or wide commercial passenger aircraft.

Solution 15. a method of replacing a first fuselage shroud on an aircraft, the method comprising:

detaching the first body hood from a fuselage of the aircraft, wherein detaching the first body hood comprises removing one or more fasteners from the first body hood that extend from the first body hood to the fuselage;

removing the first fuselage shroud from a coverage area of a fuselage of the aircraft;

placing a second fuselage shield over at least a portion of a coverage area of a fuselage of the aircraft; and

coupling the second fuselage shroud to a fuselage of the aircraft using one or more fasteners extending from the first fuselage shroud to the fuselage.

The method of any of the preceding claims, wherein removing one or more fasteners from the first body shroud extending from the first body shroud to the body comprises rotating the one or more fasteners in a loosening direction to disengage the first body shroud from the body.

Claim 17 the method of any preceding claim, wherein the second layer is hermetically sealed within an interior of the second fuselage shroud.

Solution 18. the method of any preceding solution, wherein coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners comprises coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners extending through the first layer.

Technical solution 19. a method, comprising:

placing a fuselage shield on the exterior of the fuselage of an aircraft, and

securing the fuselage shroud to the fuselage exterior using fasteners.

Solution 20. the method of any of the preceding claims, wherein the fuselage shroud is a first fuselage shroud, and wherein the method further comprises:

placing a second fuselage shield on an exterior of a fuselage of the aircraft adjacent to the first fuselage shield to form an adjoining fuselage shield that protects the exterior of the fuselage; and

securing the second fuselage shroud to the fuselage exterior using fasteners.

Solution 21. the method of any preceding solution, wherein the first fuselage shroud, the second fuselage shroud, or both are secured using a fastener adapted to separate from the first fuselage shroud, the second fuselage shroud, or both and the fuselage of the aircraft to allow the first fuselage shroud, the second fuselage shroud, or both to be replaced with a replacement shroud without affecting the exterior of the fuselage.

An aircraft defining a longitudinal direction and a lateral direction, the aircraft comprising:

a body;

a single unducted rotor engine mounted at a location spaced from the fuselage of the aircraft, said single unducted rotor engine comprising an unducted rotor assembly having a single pole rotor blade; and

a fuselage shroud attached to or integrally formed with the fuselage at a location aligned in the transverse direction with a single stage rotor blade of the unducted rotor assembly.

The aircraft of any preceding claim, further comprising:

a wing extending from the fuselage generally in the transverse direction, wherein the single unducted rotary engine is mounted to the wing.

The aircraft of any preceding claim, wherein the single unducted rotor engine is a first single unducted rotor engine, wherein the fuselage shroud is a first fuselage shroud attached to or integrally formed with a first side of the fuselage, and wherein the aircraft further comprises:

a second single unducted rotor engine, said second single unducted rotor engine comprising an unducted rotor assembly having a single pole rotor blade;

a first airfoil extending from the first side of the fuselage generally in the transverse direction, wherein the first single unducted rotary engine is mounted to the first airfoil;

a second airfoil extending from a second side of the fuselage generally in the transverse direction, wherein the second single unducted rotary engine is mounted to the second airfoil; and

a second fuselage shroud attached to or integrally formed with the second side of the fuselage at a second location aligned in the transverse direction with the single stage rotor blades of the second unducted rotor assembly.

The aircraft of any preceding claim, wherein the first fuselage shroud is asymmetrically positioned relative to the second fuselage shroud with respect to a reference plane extending through a center of the aircraft in the longitudinal and vertical directions.

The aircraft of any preceding claim, wherein the rotor assembly of the first single unducted rotor engine and the rotor assembly of the second single unducted rotor engine each rotate in the same direction of rotation, and wherein the first fuselage shroud extends higher in the vertical direction than the second fuselage shroud or extends lower in the vertical direction than the second fuselage shroud.

The aircraft of any preceding claim, wherein the first fuselage shroud defines a first absolute positioning angle relative to a top of a vertical reference line extending through a center of the fuselage, wherein the second fuselage shroud defines a second absolute positioning angle relative to the top of the vertical reference line, wherein a difference between the first absolute positioning angle and the second absolute positioning angle is greater than 5 degrees and less than 50 degrees.

An aspect 28 the aircraft of any preceding aspect, wherein the fuselage shroud defines a top end and a bottom end along a vertical direction of the aircraft, wherein the fuselage shroud defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

The aircraft of any preceding claim, wherein the fuselage shroud comprises a first zone having a first impact resistance and a second zone having a second impact resistance, wherein the first zone and the second zone are arranged along a circumference of the fuselage.

The aircraft of any preceding claim, wherein the fuselage shroud further comprises a third zone having a third impact resistance, wherein the second and third zones are disposed on opposite sides of the first zone along the circumference of the fuselage, and wherein the first impact resistance is greater than the second impact resistance and greater than the third impact resistance.

The aircraft of any preceding claim, wherein the fuselage shroud comprises a plurality of zones arranged along a circumference of the fuselage, wherein the impact resistance of the fuselage shroud varies between each of the adjacent zones.

The aircraft of any preceding claim, wherein a thickness of the fuselage shroud varies between each of the adjacent regions.

The aircraft of any preceding claim, wherein the plurality of zones comprises at least 4 zones and up to 10 zones.

The aircraft of any preceding claim, wherein the fuselage shroud defines a surface area of between 720 square inches and 15,000 square inches.

Solution 35 the aircraft of any preceding solution, wherein the aircraft is a narrow or wide commercial passenger aircraft.

A fuselage shroud assembly for use with a fuselage of an aircraft having a single unducted rotor engine, the aircraft defining a longitudinal direction and a transverse direction, the fuselage shroud assembly comprising:

a body configured to be attached to or integrally formed with a fuselage of the aircraft at a location aligned with the single unducted rotor engine in the transverse direction, the body comprising a plurality of zones configured to be arranged along a circumference of the fuselage when coupled thereto, wherein an impact resistance of the fuselage shroud varies between each of the adjacent zones.

The fuselage shroud assembly of any preceding claim, wherein the plurality of zones includes a first zone having a first impact resistance and a second zone having a second impact resistance, wherein the first zone and the second zone are configured to be arranged along a circumference of the fuselage.

The fuselage shroud assembly of any preceding claim, wherein the fuselage shroud further comprises a third zone having a third impact resistance, wherein the second zone and the third zone are disposed on opposite sides of the first zone, and wherein the first impact resistance is greater than the second impact resistance and greater than the third impact resistance.

Claim 39 the fuselage shroud assembly of any preceding claim, wherein a thickness of the fuselage shroud varies between each of the adjacent regions.

Claim 40 the fuselage shroud assembly of any preceding claim, wherein the plurality of zones comprises at least 4 zones and up to 10 zones.

Claim 41 the fuselage shroud assembly of any preceding claim, wherein the fuselage shroud defines a surface area of between 720 square inches and 15,000 square inches.

Solution 42. the fuselage shroud assembly of any preceding solution, wherein the body of the fuselage shroud assembly, when coupled to the fuselage of the aircraft, defines a top end and a bottom end in a vertical direction of the aircraft, wherein the body, when coupled to the fuselage of the aircraft, defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

An aircraft defining a longitudinal direction and a lateral direction, the aircraft comprising:

a body;

an engine mounted at a location spaced from a fuselage of the aircraft, the engine including a plurality of rotor blades; and

a fuselage shroud attached to or integrally formed with the fuselage at a location aligned with the plurality of rotor blades in the lateral direction, the fuselage shroud including a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

The aircraft of any preceding claim, wherein the thickness of the first layer is different from the thickness of the second layer.

Solution 45 the aircraft of any preceding solution, wherein the first layer is an energy distribution layer, and wherein the second layer is an energy absorption layer.

Solution 46. the aircraft of any preceding solution, wherein the first layer has a thickness of at least 0.05 inches and up to 2.5 inches, and wherein the second layer has a thickness of at least 0.25 inches and up to 4 inches.

Solution 47. the aircraft of any preceding solution, further comprising a third layer, wherein the third layer is a load spreading layer, and wherein the third layer has a thickness of at least 0.05 inches and up to 2.5 inches.

Solution 48 the aircraft of any preceding solution, wherein the first layer is formed from kevlar, metal, carbon fiber composite, ceramic, or a combination thereof, and wherein the second layer comprises a honeycomb, a mesh, a foam, a polyurethane material, or a combination thereof.

Claim 49 the aircraft of any preceding claim, wherein the first density is greater than the second density.

Solution 50 the aircraft of any preceding solution, wherein the first density is at least about 100% greater than the second density.

Solution 51 the aircraft of any preceding solution, wherein the energy distribution layer is positioned closer to the plurality of rotor blades than the energy absorption layer.

The aircraft of any preceding claim, wherein the fuselage shroud further comprises a load distribution layer defining a third density, wherein the third density is greater than the first density.

The aircraft of any preceding claim, wherein the energy distribution layer is positioned closer to the plurality of rotor blades than the energy absorbing layer, and wherein the energy absorbing layer is positioned closer to the plurality of rotor blades than the load spreading layer.

The aircraft of any preceding claim, wherein the second layer is hermetically sealed within an interior of the fuselage shroud.

Solution 55 the aircraft of any preceding solution, wherein the fuselage shroud is coupled to the fuselage through the first layer.

Solution 56. the aircraft of any preceding solution, wherein the first layer and the second layer are secured to each other at least in part using mechanical clamps, resin bonding, compression wrapping, weld joints, lamination, or a combination thereof.

Solution 57 the aircraft of any preceding solution, wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer, and wherein the second layer is formed by a plurality of plates and a plurality of spacers positioned between adjacent plates of the plurality of plates.

Solution 58. the aircraft of any preceding solution, wherein the aircraft is a narrow or wide commercial passenger aircraft.

A fuselage shroud assembly for use with a fuselage of an aircraft having an unducted rotor engine, the aircraft defining a longitudinal direction and a transverse direction, the fuselage shroud assembly comprising:

a body formed from a plurality of layers, the body configured to be attached to or integrally formed with a fuselage of the aircraft at a location aligned with the unducted rotor engine in the transverse direction, the plurality of layers including a first layer and a second layer, the first layer defining a first density and the second layer defining a second density, the first density being different than the second density.

Solution 60 the fuselage shroud assembly of any preceding solution, wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer, and wherein the first density is greater than the second density.

Claim 61 the fuselage shroud assembly of any preceding claim, wherein the first density is at least about 100% greater than the second density.

Solution 62. the airframe shroud assembly of any preceding solution, wherein the energy distribution layer is configured to be positioned closer to the unducted rotor engine than the energy absorption layer.

The airframe shroud assembly as recited in any preceding claim, wherein the airframe shroud further comprises a load spreading layer defining a third density, wherein the third density is greater than the first density, wherein the energy distribution layer is configured to be positioned closer to the unducted rotor engine than the energy absorption layer, and wherein the energy absorption layer is configured to be positioned closer to the unducted rotor engine than the load spreading layer.

These and other features, aspects, and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the principles of the invention.

Drawings

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which:

FIG. 1 is a schematic cross-sectional view of a gas turbine engine according to an exemplary aspect of the present disclosure.

FIG. 2 is a schematic cross-sectional view of a gas turbine engine according to another exemplary aspect of the present disclosure.

FIG. 3 is a schematic illustration of an aircraft incorporating the gas turbine engine according to FIG. 1 and/or FIG. 2.

FIG. 4 is a schematic view of a fuselage shroud according to an exemplary embodiment of the present disclosure.

FIG. 5 is a cross-sectional view of a fuselage shroud according to another exemplary embodiment of the present disclosure.

FIG. 6 is a cross-sectional view of a fuselage shroud according to yet another exemplary embodiment of the present disclosure.

FIG. 7 is a cross-sectional view of a fuselage shroud according to yet another exemplary embodiment of the present disclosure.

Fig. 8 is a perspective view of a portion of the exemplary fuselage shroud of fig. 7.

Fig. 9 is a schematic view of the fuselage of the aircraft of fig. 3 including a first fuselage shroud.

Fig. 10 is a schematic view of the fuselage of the aircraft of fig. 3 including a second fuselage shroud.

Fig. 11 is a cross-sectional view from the front to the rear of the fuselage of the aircraft of fig. 3.

Fig. 12 is a cross-sectional view looking from the front to the back of a fuselage of an aircraft having a fuselage shroud according to an exemplary embodiment of the present disclosure.

Fig. 13 is a cross-sectional view looking forward and aft of a fuselage of an aircraft having a fuselage shroud according to another exemplary embodiment of the present disclosure.

Fig. 14 is a schematic plan view of a fuselage of an aircraft including a fuselage shroud according to the present disclosure.

Fig. 15 is a schematic view of the exemplary fuselage shroud of fig. 14.

FIG. 16 is a flow chart of a method for removing and replacing a fuselage shroud of a fuselage of an aircraft.

Detailed Description

Reference now will be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention.

The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

As used herein, the terms "first," "second," and "third" are used interchangeably to distinguish one element from another, and are not intended to denote the position or importance of the various elements.

The terms "forward" and "aft" refer to relative positions within the gas turbine engine or vehicle and to normal operating attitudes of the gas turbine engine or vehicle. For example, with respect to a gas turbine engine, front means a position closer to the engine inlet, and rear means a position closer to the engine nozzle or exhaust.

The terms "upstream" and "downstream" refer to relative directions with respect to fluid flow in a fluid passageway. For example, "upstream" indicates the direction from which the fluid flows, and "downstream" indicates the direction to which the fluid flows.

Unless otherwise specified herein, the terms "coupled," "fixed," "attached," and the like mean directly coupled, fixed, or attached, as well as indirectly coupled, fixed, or attached through one or more intermediate components or features.

The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as "about", "about" and "approximately", are not to be limited to the precise value specified. In at least some examples, the approximating language may correspond to the precision of an instrument for measuring the value, or the precision of a method or machine for constructing or manufacturing the component and/or system.

For example, the approximating language may be represented within a margin of 1, 2, 4, 10, 15, or 20 percent. These approximate margins may apply to a single value, margins that define a range between either or both endpoints and/or endpoints of a range of values.

Here and throughout the specification and claims, unless the context or language indicates otherwise, range limitations are combined and interchanged, such ranges are equivalent and include all the sub-ranges contained therein. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

As mentioned above, the inventors of the present disclosure have found that a means for providing the desired fuselage protection for the fuselage of an aircraft, while maintaining the flexibility to modify the fuselage protection over time, would be useful. In at least certain exemplary aspects, such benefits may be provided to aircraft having engines that include rotor assemblies with one stage of rotor blades (such as unducted rotor engines in certain embodiments) through the use of a fuselage shroud removably coupled to the fuselage of the aircraft at a location aligned with a rotor blade stage of the rotor assembly in a lateral direction of the aircraft.

For example, in certain exemplary embodiments, the fuselage shroud may be removably coupled to the fuselage using a plurality of mechanical fasteners arranged at a density of at least one fastener per inch and up to 25 fasteners per inch.

Additionally or alternatively, some of these benefits may be realized by including a fuselage shroud defining a forward end and an aft end, wherein the forward end defines a forward end cone angle of at least 1 degree and up to 15 degrees and an aft end cone angle of at least 1 degree and up to 15 degrees.

Referring now to the drawings, FIG. 1 illustrates an elevation cross-sectional view of an exemplary embodiment of a gas turbine engine 10, which may incorporate one or more inventive aspects of the present disclosure. In particular, the exemplary gas turbine engine 10 of FIG. 1 is configured as a turboprop engine that defines an axial direction A, a radial direction R, and a circumferential direction C (e.g., extending about the axial direction A, see FIG. 4). As seen in FIG. 1, the engine 10 includes an array of airfoils disposed about a central longitudinal axis 14 of the engine 10, and more particularly includes an array of rotor blades 16 disposed about the central longitudinal axis 14 of the engine 10. The rotor blades 16 are arranged in a typically equidistant relationship about the centerline 14, and each has a root 22 and a tip 24 and a span defined therebetween. Rotor assembly 12 also includes a hub 45 forward of the plurality of rotor blades 16.

It will be appreciated that, as used herein, the term "rotor blade" is used to generally refer to any rotatable blade, typically having an airfoil shape, that may be rotated by the engine 10 to generate thrust or to compress air for the engine 10. For example, in the embodiment of FIG. 1, the rotor blades 16 are sometimes referred to as propeller blades, whereas in the embodiment of FIG. 2 discussed below, the rotor blades 16 are sometimes referred to as fan blades.

In addition, the engine 10 includes a turbine 30, the turbine 30 having a core (or high speed system) 32 and a low speed system. The core 32 generally includes a high-speed compressor 34, a high-speed turbine 36, and a high-speed shaft 38 extending therebetween and connecting the high-speed compressor 34 and the high-speed turbine 36. The high-speed compressor 34 (or at least the rotating components thereof), the high-speed turbine 36 (or at least the rotating components thereof), and the high-speed shaft 38 may collectively be referred to as the high-speed spool of the engine. Further, the combustion section 40 is located between the high speed compressor 34 and the high speed turbine 36. The combustion section 40 may include one or more configurations for receiving a mixture of fuel and air and providing a flow of combustion gases through the high-speed turbine 36 to drive a high-speed rotating shaft.

The low speed system similarly includes a low speed turbine 42 (or power turbine) and a low speed shaft 46 extending between and connecting the low speed turbine 42 and the plurality of rotor blades 16. More specifically, as shown in the embodiment illustrated in FIG. 1, the low speed turbine 42 rotates and rotational energy is transferred to the rotor blades 16 by a low speed shaft 46.

Still referring to FIG. 1, the turbine 30 is generally enclosed in a fairing 48. The fairing 48 at least partially defines an inlet 50 and an exhaust 52 and includes a turbine flow path 54 extending between the inlet 50 and the exhaust 52.

However, it will be appreciated that the exemplary gas turbine engine of FIG. 1 is provided as an example only. In other exemplary embodiments, the gas turbine engine may have any other suitable configuration, such as any other suitable unducted or open rotor configuration. For example, referring now to FIG. 2, an elevation cross-sectional view of a gas turbine engine 10 in accordance with another exemplary embodiment of the present disclosure is provided. In particular, the exemplary gas turbine engine 10 of FIG. 2 is configured as a single unducted rotor engine. The exemplary single unducted rotor engine of FIG. 2 can be constructed in a similar manner to the exemplary turboprop engine of FIG. 1. For example, the exemplary single unducted rotor engine of fig. 2 generally defines an axial direction a, a radial direction R, and a circumferential direction C (see, e.g., fig. 3, extending about axial direction a). Further, the engine 10 includes an array of airfoils disposed about a central longitudinal axis 14 of the engine 10, and more particularly includes an array of rotor blades 16 disposed about the central longitudinal axis 14 of the engine 10.

In addition, the engine 10 includes a turbine 30, the turbine 30 having a core (or high speed system) 32, a low speed system, and a combustion section 40 located between a high speed compressor 34 and a high speed turbine 36 of the core 32. Further, as with the previous embodiment, the low speed system includes a low speed turbine 42 and a low speed shaft 46. However, for the illustrated embodiment, the low speed system also includes a low speed compressor or booster 44, and a low speed shaft 46 extends between and connects the low speed compressor 44 and the low speed turbine 42.

It will be appreciated that while engine 10 is depicted with low speed compressor 44 positioned forward of high speed compressor 34, in certain embodiments, compressors 34, 44 may be in a staggered arrangement. Additionally or alternatively, although the engine 10 is depicted with the high-speed turbine 36 positioned forward of the low-speed turbine 42, in certain embodiments, the turbines 36, 42 may similarly be in a staggered arrangement.

Also similar to the embodiment of FIG. 1, for the embodiment of FIG. 2, the turbine 30 is generally enclosed in a fairing 48, the fairing 48 at least partially defining an inlet 50 and an exhaust 52, and including a turbine flowpath 54 extending between the inlet 50 and the exhaust 52. For the illustrated embodiment, the inlet 50 is an annular or axisymmetric 360-degree inlet 50 that provides a path for incoming atmospheric air to enter the turbine flow path 54 (as well as the compressors 44, 34, combustion section 40, and turbines 36, 42).

Moreover, the exemplary gas turbine engine 10 depicted in FIG. 2 additionally includes a non-rotating vane assembly 18 positioned aft (i.e., non-rotating relative to the central axis 14) of the rotor assembly 12, the non-rotating vane assembly 18 including an array of airfoils also disposed about the central axis 14, and more particularly including an array of vanes 20 disposed about the central axis 14. The rotor blades 16 are arranged in a typically equidistant relationship about the centerline 14, and each has a root 22 and a tip 24 and a span defined therebetween. It will be appreciated that the vanes 20 each have a root 26 and a tip 28 and a span defined therebetween. Rotor assembly 12 also includes a hub 45 forward of the plurality of rotor blades 16.

Briefly, for the illustrated embodiment, the inlet 50 is located between the rotor blade assembly 12 and the stationary or stationary vane assembly 18. Such locations may be advantageous for a variety of reasons, including management of icing performance and protection of the inlet 50 from various objects and materials as may be encountered in operation. However, it will be appreciated that in other embodiments, the inlet 50 may be positioned at any other suitable location, such as aft of the vane assembly 18, arranged in a non-axisymmetric manner, or the like.

Still referring to FIG. 2, the vane assembly 18 extends from the cowl 48 and is positioned aft of the rotor assembly 12. The vanes 20 of the vane assembly 18 may be mounted to a fixed frame or other mounting structure and do not rotate relative to the central axis 14. For reference purposes, fig. 1 also depicts a forward direction, represented by arrow F, which in turn defines the front and rear portions of the system. As shown in fig. 1, the rotor assembly 12 is located forward of the turbine 30 in a "puller" configuration, and the exhaust 52 is located aft of the guide vanes 20. As will be appreciated, the vanes 20 of the vane assembly 18 may be configured to straighten the airflow from the rotor assembly 12 (e.g., reduce vortices in the airflow) to increase the efficiency of the engine 10. For example, the vanes 20 may be sized, shaped, and configured to impart a reactive swirl to the airflow from the rotor blades 16 such that, in a downstream direction behind the two rows of airfoils (e.g., blades 16, vanes 20), the airflow has a greatly reduced degree of swirl, which may translate into an increased level of induced efficiency. Further discussion regarding the vane assembly 18 is provided below.

However, it will be appreciated that the exemplary single rotor unducted engine depicted in FIG. 2 is by way of example only, and that in other exemplary embodiments, engine 10 may have any other suitable configuration including, for example, any other suitable number of shafts or rotating shafts, turbines, compressors, and the like. Additionally or alternatively, in other exemplary embodiments, any other suitable gas turbine engine may be provided. For example, in other exemplary embodiments, the gas turbine engine may be a ducted turbofan engine, a turboshaft engine, a turboprop engine, a turbojet engine, or the like. Further, while the exemplary engine 10 depicted in FIG. 2 includes a single unducted rotor, in other exemplary embodiments, the engine can include a plurality of unducted rotors (e.g., pairs of counter-rotating rotors).

Referring now to FIG. 3, a schematic illustration of an aircraft 100 including engine 10 according to an exemplary aspect of the present disclosure is provided. The depicted exemplary aircraft 100 generally includes a fuselage 102, a first wing 104A extending outwardly from a first/left side of the fuselage 102, and a second wing 104B extending outwardly from a second/right side of the fuselage 102. The exemplary aircraft 100 also includes a first engine 10A mounted to the first wing 104A in an under-wing configuration and a second engine 10B mounted to the second wing 104B in an under-wing configuration. The first engine 10A and the second engine 10B may each be configured in a similar manner as the exemplary engine 10 of FIG. 1. Accordingly, each of the first and second engines 10A, 10B includes a rotor assembly 12 rotatable about a centerline axis 14 of the respective engine.

As will be appreciated, the rotor assemblies 12 of the first and second engines 10A, 10B include a single stage of unducted rotor blades 16. As such, in the event of a failure, there is no nacelle or similar structure surrounding the stage rotor blade 16 to house the rotor blade 16. Although not depicted, the first and second engines 10A and 10B may additionally include stage one stationary guide vanes (similar to the stage one guide vanes 18 of fig. 1).

Thus, for the depicted exemplary aircraft 100, the aircraft 100 includes a first fuselage shroud 106 and a second fuselage shroud 108, the first fuselage shroud 106 being attached to or integrally formed with a first side/left side of the fuselage 102 adjacent the rotor assembly 12 of the first engine 10A, the second fuselage shroud 108 being attached to or integrally formed with a second side/right side of the fuselage 102 adjacent the rotor assembly 12 of the second engine 10B.

More particularly, for the depicted embodiment, the fuselage 102 includes an exterior 103 of the fuselage, which is generally an exterior surface of the fuselage 102, defined by an exterior layer of the fuselage 102 (e.g., an exterior layer of sheet metal, optionally including one or more coatings). A first fuselage cover 106 is placed over and secured to the fuselage exterior 103 and similarly a second fuselage cover 108 is also placed over and secured to the fuselage exterior 103. In this manner, it will be appreciated that for the depicted embodiment, the first and second fuselage shrouds 106, 108 are not integrated into the original design of the fuselage 102 and/or are located within the outer layers of the fuselage 102, but are added as a supplement to the fuselage exterior 103 as described herein.

More particularly, and with particular reference to the first engine 10A, it will be appreciated that the aircraft 100 generally defines a longitudinal direction L1 and a transverse direction L2. The first fuselage shroud 106 is attached to the fuselage 102 at a location aligned with the plurality of rotor blades 16 of the rotor assembly 12 of the first engine 10A along the longitudinal direction L1. Further, the first fuselage shroud 106 defines a length 110 along the longitudinal direction L1, and the plurality of rotor blades 16 of the rotor assembly 12 define a rotor assembly diameter 112. For the depicted embodiment, the length 110 of the first fuselage shroud 106 is equal to at least about 50% of the rotor assembly diameter 112, such as at least about 60% of the rotor assembly diameter 112, such as at least about 75% of the rotor assembly diameter 112, such as up to about 800% of the rotor assembly diameter 112.

Notably, the depicted exemplary aircraft 100 may generally be referred to as a "narrow-body" aircraft having a single aisle extending along its length. In certain embodiments, the fuselage defines a width 105 along the lateral direction L2 of at least 80 inches, such as at least 90 inches, such as at least 100 inches, such as at least 110 inches, such as at least 130 inches. However, in other embodiments, the aircraft 100 may alternatively be configured as a "wide body" aircraft having a plurality of aisles extending along its length and a wider fuselage 102, such as up to 400 inches wide or up to 350 inches wide or up to 300 inches wide. In at least some example embodiments, the narrow body aircraft may have a maximum seat capacity of 295 passengers, while the wide body aircraft may be able to accommodate between 250 and 600 passengers. For example, two side-by-side aircraft typically accommodate 4 to 19 passengers, three side-by-side aircraft typically accommodate 24 to 45 passengers, four side-by-side aircraft typically accommodate 44 to 80 passengers, five side-by-side aircraft typically accommodate 85 to 130 passengers, and six side-by-side aircraft typically accommodate 120 to 230 passengers. In contrast, a spur aircraft is generally smaller than narrow and wide body aircraft, the flight time can be shorter, and fewer passengers and/or cargo are carried. For example, a typical spur aircraft is designed to carry 100 passengers or less.

For embodiments of the present disclosure, an aircraft may have cruise altitude engines and operate at or above 0.5 Mach, about 0.55 Mach, and about 0.85 Mach, or between 0.75 Mach and 0.85 Mach, for cruise altitudes. For example, an aircraft may have a cruise speed at a cruise altitude. In various embodiments, the engine is applied to a vehicle having a cruising height of up to about 65,000 feet. In certain embodiments, the cruising height is between about 28,000 feet and about 45,000 feet. In certain further embodiments, cruise altitude is represented in an altitude layer based on standard barometric pressure at sea level, where cruise flight conditions are between FL280 and FL 650. In another embodiment, the cruise flight condition is between FL280 and FL 450. In certain further embodiments, the cruise altitude is defined based at least on atmospheric pressure, wherein the cruise altitude is between about 4.85 psig and about 0.82 psig based on a sea level pressure of about 14.70 psig and a sea level temperature of about 59 degrees Fahrenheit. In another embodiment, the cruising height is between about 4.85 psi and about 2.14 psi. It should be appreciated that, in certain embodiments, the range of cruising altitude defined by pressure may be adjusted based on different reference sea level pressures and/or sea level temperatures.

In this manner, it will be appreciated that the aircraft 100 is generally configured to carry a greater number of passengers, crew members, and/or cargo than smaller aircraft, such as typical branch turboprop aircraft. For these smaller aircraft, the rotor blades (e.g., propellers) of the engines tend to be relatively small and light, with relatively small diameters, and the power delivered by the engines is lower than the larger and more powerful engines used on narrow and wide body class commercial passenger aircraft. Furthermore, in the disclosed embodiments of the unducted rotor engine, the delivered power and rotor or blade size can be significantly larger than a turboprop, so that the risk of catastrophic damage in the event of a failure can be considered higher. For example, the rotor or blade may be 11 to 14 feet in diameter, or 11 feet, 12 feet, or between 12 and 14 feet in diameter. In view of these factors, while addressing the effects in terms of weight, cost and complexity increase and efficiency reduction (e.g., due to aerodynamic drag) associated with shrouds, the inventors have completed a design that is believed to strike a proper balance between safety and efficiency, replaceability and maintenance of the shroud. It will be appreciated that embodiments of the shrouds disclosed herein address unique challenges facing both narrow and wide-bodied commercial passenger aircraft engines or aircraft designers in terms of passenger and crew protection.

In contrast to current narrow and wide body aircraft, the inventors of the present disclosure have discovered that, while increasing weight and minimizing (but still existing) additional drag on the aircraft 100, the benefits and requirements of the fuselage shrouds described herein are weighed in favor of including the fuselage shroud when it is desired to incorporate an open rotor engine (rather than, for example, a ducted turbofan engine), and particularly when it is desired to incorporate an open rotor engine with rotor blades defining a relatively large diameter (such as at least 6 feet, such as at least 8 feet, such as at least 10 feet, such as at least 12 feet, such as up to 22 feet; such engines are depicted in the embodiment of FIG. 2). As will be appreciated from the description herein, the disclosed fuselage shroud may allow an aircraft to incorporate an engine 10 with unducted rotor blades without having to redesign and/or rebuild the fuselage 102 to incorporate the fuselage shroud that the inventors have found beneficial.

However, it will be appreciated that while described above as being applied to both narrow and wide body aircraft, in other embodiments, aspects of the present disclosure may further be applied to spur aircraft.

Further, referring now to fig. 4, it will be appreciated that the first fuselage shroud 106 defines a plurality of layers. More particularly, the first fuselage shroud 106 includes a first layer and a second layer. In the illustrated embodiment, the first layer is an energy distribution layer 116 and the second layer is an energy absorption layer 118. The depicted exemplary fuselage shroud 106 additionally includes a third layer, which for the illustrated embodiment is a load spreading layer 114. The load spreading layer 114 is positioned adjacent to the fuselage 102 and the energy distribution layer 116 is spaced from the fuselage 102. Further, an energy absorbing layer 118 is positioned between the load spreading layer 114 and the energy absorbing layer 118. More specifically, for the illustrated embodiment, the energy distribution layer 116 is positioned closer to the stage of unducted rotor blade 16 of first engine 10A than the energy absorption layer 118, and the energy absorption layer 118 is positioned closer to the stage of unducted rotor blade 16 of first engine 10A than the load distribution layer 114.

In the event of a failure of the rotor assembly 12 of the first engine 10A, debris may impact the energy distribution layer 116, which may prevent such debris from cutting and penetrating the first airframe shroud 106. The energy absorbing layer 118 may absorb energy from debris transferred from the energy distribution layer 116. Finally, the load spreading layer 114 may distribute the energy from the energy absorbing layer 118 throughout the fuselage 102 to prevent any deformation of the fuselage 102.

In certain exemplary embodiments, the energy distribution layer 116 may be a metal (such as one or more pieces of metal sheet), kevlar, carbon fiber composite (e.g., such as carbon fiber composite with a polymeric resin such as epoxy), ceramic (such as ceramic sheet or ceramic fiber), combinations thereof, or other materials capable of preventing debris from penetrating therethrough. The load spreading layer 114 may be a metal layer, a graphite or epoxy layer, a carbon fiber composite material (e.g., such as a carbon fiber composite material with a polymeric resin such as an epoxy), or the like.

Further, it will be appreciated that the energy absorbing layer 118 may be formed of any material capable of absorbing a desired amount of energy. For example, referring now to fig. 5 and 6, enlarged partial cross-sectional views of two fuselage shrouds 106 according to two exemplary embodiments of the present disclosure are provided. Each fuselage shroud 106 may be constructed in a similar manner as the exemplary first fuselage shroud 106 described above. Thus, the fuselage shroud 106 of fig. 5 and 6 generally includes a load spreading layer 114, an energy absorbing layer 118, and an energy distributing layer 116. The load spreading layer 114 and the energy distribution layer 116 may be formed of the materials described above or other suitable materials. In these embodiments, the energy absorbing layer 118 is formed of a relatively low density material, having a low percent solidity (volume percent of material that is solid at rated stress (compared to air or other gases)). For example, in these embodiments, the material forming the energy absorbing layer 118 may define a solidity percentage of less than 75%, such as less than 60%, such as less than 50%, such as less than 40%, such as at least 10%, such as at least 25%.

With particular reference to fig. 5, it will be appreciated that the energy distribution layer 116 is formed from a mesh structure. The lattice structure includes a plurality of interweaving members 140, the interweaving members 140 being bendable to allow the structure to compress and absorb energy in the event that the body shroud 106 is impacted by debris. The mesh structure may be formed by a 3D printing process/additive manufacturing process or any other suitable forming process. The member 140 may be formed of metal, plastic, elastomeric material, or the like.

With particular reference to fig. 6, it will be appreciated that the energy distribution layer 116 is formed of a honeycomb structure. The honeycomb structure includes a plurality of members 142 connected to form a polygonal geometric pattern, and more particularly, for the illustrated embodiment, a hexagonal geometric pattern. The member 142 may be flexible to allow the material to compress and absorb energy in the event the fuselage shroud 106 is impacted by debris. The honeycomb structure may be formed by a 3D printing process/additive manufacturing process or any other suitable forming process. The member 142 may be formed of metal, plastic, elastomeric material, or the like.

However, it will be appreciated that in other exemplary embodiments, the energy distribution layer 116 may be formed of any other suitable material/structure. For example, in other embodiments, the energy distribution layer 116 may be formed of, for example, a foam material, a polyurethane material, or any other suitable material capable of absorbing energy. Additionally, the energy distribution layer 116 may be formed of any other suitable structure capable of absorbing energy.

For example, referring now to fig. 7 and 8, enlarged partial views of the fuselage shroud 106 according to another exemplary embodiment of the present disclosure are provided. The depicted fuselage shroud 106 may also be constructed in a similar manner as the exemplary first fuselage shroud 106 described above. Thus, the fuselage shrouds of fig. 7 and 8 generally include a load spreading layer 114, an energy absorbing layer 118, and an energy distributing layer 116. The load spreading layer 114 and the energy distribution layer 116 may be formed of the materials described above or any other suitable materials. However, the energy absorbing layer 118 of the illustrated embodiment is formed by a plurality of plates 144 and a plurality of spacers 146 positioned between adjacent plates 144 of the plurality of plates 144.

In particular, referring first to fig. 7, providing an enlarged partial cross-sectional view of the energy distribution layer 116, it will be appreciated that the plurality of plates 144 are spaced along a thickness 150 of the fuselage shroud 106 between the load distribution layer 114 and the energy distribution layer 116. Further, the depicted plurality of plates 144 includes at least two plates 144, and more particularly four plates 144. The plurality of plates 144 may include up to twenty-five (25) plates 144. The plurality of plates 144 may be formed from a metal plate material, a metal alloy, a composite material, or any other suitable material. For example, in certain embodiments, one or more of the plurality of plates 144 may be formed from a metal composite, steel, depleted uranium, tungsten, titanium, inconel, molybdenum, aluminum, magnesium, aluminum lithium alloy, combinations thereof, and the like.

Further, referring now particularly to fig. 8, a perspective view of a section of the pair of adjacent plates 144 is provided, it will be appreciated that between each pair of adjacent plates 144, the energy absorbing layer 118 includes a plurality of spacers 146. For example, the energy absorbing layer 118 may include at least two spacers 146, and up to one hundred (100) spacers 146, such as up to fifty (50) spacers 146, such as up to twenty-five (25) spacers 146. The spacers 146 may define an aspect ratio of between 10:1 and 1:10, such as between 5:1 and 1:5, such as between 2:1 and 1:2, such as equal to about 1: 1. Further, referring also to fig. 7, it will be appreciated that the spacers 146 are substantially misaligned along the thickness 150 of the energy absorbing layer 118. In particular, for the illustrated embodiment, the spacers 146 defined in the first gaps 148A between adjacent plates 144 do not overlap the spacers 146 in the second gaps 148B (positioned adjacent the first gaps 148A and partially defined by the common plate 144) when viewed along the thickness 150 of the fuselage shroud 106.

In this manner, it will be appreciated that for the example energy absorbing layer 118 depicted in fig. 7 and 8, the plate 144 may deform to absorb energy transferred thereto from the energy distribution layer 116.

Referring now also back to fig. 4, it will be appreciated from the discussion hereinabove that the load spreading layer 114 defines a first density, the energy absorbing layer 118 defines a second density, and the energy distributing layer 116 defines a third density. For the depicted embodiment, the first density and the third density are greater than the second density of the energy absorbing layer 118. For example, in certain exemplary embodiments, the first density, the third density, or both may be at least about 20% greater than the second density, such as at least about 50% greater, such as at least about 100% greater, such as at least about 200% greater, such as at least about 500% greater, such as up to about 10,000% greater than the second density.

Further, with particular reference to the labeled circle 4 in fig. 4, it will be appreciated that the energy distribution layer 116 defines a first thickness 150A, the energy absorbing layer 118 defines a second thickness 150B, and the load spreading layer 114 defines a third thickness 150C. As used herein, the term "thickness" refers to the maximum thickness of the component being described, such as the maximum thickness of a layer of the fuselage shroud 106.

For the illustrated embodiment, the first thickness 150A is at least 0.05 inches and up to 2.5 inches, such as at least 0.1 inches, such as at least 0.5 inches, such as at least 0.75 inches, such as up to 2.25 inches, such as up to 2 inches. Further, for the illustrated embodiment, the third thickness 150C is at least 0.05 inches and up to 2.5 inches, such as at least 0.1 inches, such as at least 0.5 inches, such as at least 0.75 inches, such as up to 2.25 inches, such as up to 2 inches. Further, also for the illustrated embodiment, the second thickness 150B is at least 0.25 inches and up to 4 inches, such as at least 0.35 inches, such as at least 0.5 inches, such as at least 1 inch, such as at least 2 inches, such as up to 3.75 inches, such as up to 3.5 inches.

In this manner, it will be appreciated that the second thickness 150B of the energy absorbing layer 118 may be greater than the first and third thicknesses 150A, 150C, such as at least about 50% greater, such as at least about 100% greater, such as up to about 10000% greater. This may allow for a lower density of the energy absorbing layer 118, which may allow the energy absorbing layer 118 to absorb more energy in the event that the fuselage shroud 106 is impacted by debris.

As will also be appreciated from the figures and discussion herein, it may be beneficial to construct and/or orient fuselage shrouds with respect to estimated debris intended to protect the fuselage 102 from its harm. For example, referring now to fig. 9 and 10 (and also back to fig. 3), it will be appreciated that in certain exemplary embodiments, the first fuselage shroud 106 may be configured differently than the second fuselage shroud 108. For example, it will be appreciated that the plurality of rotor blades 16 of the rotor assemblies 12 of the first and second engines 10A, 10B rotate in the same rotational direction, as indicated by the circular arrows (extending about the centerline 14) in fig. 3, but approach the airframe 102 in a different manner given their positions on opposite sides of the airframe 102. For example, the rotor blades 16 of the rotor assemblies 12 of the first engine 10A approach from below the aircraft 100, while the rotor blades 16 of the rotor assemblies 12 of the second engine 10B approach from above the aircraft 100. As such, in the event of a failure of these engines, the estimated impact of debris from the first engine 10A may be different from the estimated impact of debris from the second engine 10B.

Thus, in at least certain exemplary embodiments, the first fuselage shroud 106 is asymmetrically positioned relative to the second fuselage shroud 108 with respect to a reference plane 120, the reference plane 120 extending through the fuselage 102 and the center 152 of the aircraft 100 along the longitudinal direction L1 and the vertical direction V of the aircraft 100.

In particular, for the depicted embodiment, the first fuselage shroud 106 may be mounted to the fuselage 102 at a different location and/or in a different orientation than the second fuselage shroud 108. More particularly, with particular reference to fig. 9 (providing a plan view of a first side/left side of the fuselage 102) and 10 (providing a plan view of a second side/right side of the fuselage 102), it will be appreciated that the first and second fuselage shrouds 106, 108 may be mounted in a manner specific to a particular engine, and in a manner that best accommodates any debris that may be generated by such an engine.

More particularly, as will also be appreciated from fig. 9 and 10, the asymmetric positioning of the first and second fuselage shrouds 106, 108 relative to the reference plane 120 results from the vertical positioning of the first and second fuselage shrouds 106, 108. For example, the first fuselage shroud 106 defines a top 122 and a bottom 124 along the vertical direction V, and similarly, the second fuselage shroud 108 defines a top 126 and a bottom 128 along the vertical direction V. The top portion 122 of the first fuselage shroud 106 is positioned higher in the vertical direction V than the top portion 126 of the second fuselage shroud 108, and thus closer to the top portion 130 of the fuselage 102. Furthermore, the bottom 124 of the second fuselage shroud 108 is positioned lower than the bottom 128 of the first fuselage shroud 106 in the vertical direction V, and thus closer to the bottom 132 of the fuselage 102.

Such a configuration can also be seen in fig. 11, fig. 11 providing a cross-sectional view from the front to the back of the fuselage 102 of the aircraft of fig. 3. As described above, the fuselage 102 includes the first fuselage shroud 106 and the second fuselage shroud 108. The first fuselage shroud 106 includes a top portion 122 and a bottom portion 124, and the second fuselage shroud 108 includes a top portion 126 and a bottom portion 128. As depicted in fig. 11, the first fuselage shroud 106 assembly defines a first absolute positioning angle 154 relative to a top of a vertical reference line extending through the center 152 of the fuselage 102 or, more particularly, relative to the top of the reference plane 120. Similarly, the top of the second fuselage shroud 108 assembly relative to a vertical reference line extending through the center 152 of the fuselage 102 or more particularly relative to the top of the reference plane 120 defines a second absolute positioning angle 156. As used herein, the term "absolute positioning angle" refers to the absolute value of the angle between two lines. Further, it will be appreciated that the absolute positioning angle of the first fuselage shroud 106 is measured from a reference line 158 (which extends from the center 152 of the fuselage 102 and the center of the first fuselage shroud 106) (as measured along the circumference of the fuselage 102), and similarly, the absolute positioning angle of the second fuselage shroud 108 is measured from a reference line 160 (which extends from the center 152 of the fuselage 102 and the center of the second fuselage shroud 108) (also as measured along the circumference of the fuselage 102).

For the illustrated embodiment, the difference between the first absolute positioning angle 154 and the second absolute positioning angle 156 is at least five degrees and up to fifty (50) degrees. For example, in certain exemplary embodiments, the difference between the first absolute positioning angle 154 and the second absolute positioning angle 156 may be at least ten degrees, such as at least fifteen (15) degrees, such as up to forty-five (45) degrees, such as up to forty (40) degrees, such as up to thirty-five (35) degrees.

For the depicted embodiment, as will be appreciated, the asymmetric positioning of the first and second fuselage shrouds 106, 108 may provide a desired amount of protection for the fuselage 102 without requiring excessive fuselage armor, which may result in an overall heavier aircraft 100 and may also increase airflow resistance of the aircraft 100.

Further, it will be appreciated that the first and second fuselage shrouds 106, 108 may be sized and/or arranged to provide the desired coverage for the particular gas turbine engine under consideration. For example, still referring to fig. 11, it will be appreciated that the first fuselage shroud 106 defines a coverage span measured along a circumference of the fuselage 102. More particularly, it will be appreciated that the first fuselage shroud 106 defines a span angle 162 of coverage between the top 122 and bottom 124 of the first fuselage shroud 106 as measured from the center 152 of the fuselage 102. The coverage span angle 162 of the first body shroud 106 is at least forty-five (45) degrees and up to one hundred and eighty (180) degrees. For example, in certain exemplary embodiments, the coverage span angle 162 of the first fuselage shroud 106 may be at least about fifty-five (55) degrees and up to about one hundred twenty (120) degrees. It will be appreciated that the second fuselage shroud 108 may define a similar coverage span angle.

In this manner, it will also be appreciated that the fuselage shroud 106 may define a surface area sufficient to provide a desired amount of coverage. In at least certain exemplary embodiments, the first fuselage shroud 106, the second fuselage shroud 108, or both, may define a surface area of at least 720 square inches and up to 15,000 square inches. For example, the first fuselage shroud 106, the second fuselage shroud 108, or both, may define a surface area of at least 1000 square inches, such as at least 1200 square inches, such as up to 13,000 square inches, such as up to 10,000 square inches.

As explained above, certain regions of the airframe 102 may be more susceptible to impact with higher forces from debris than other regions due to, for example, proximity to the gas turbine engine, the rotational direction of the rotor blades 16 of the gas turbine engine, and the like. To further protect against such higher force impacts without unnecessarily increasing the weight of the fuselage shroud 106 and the aircraft, in at least certain exemplary embodiments, the fuselage shroud 106 may be designed to accommodate impacts of different forces at various locations along the fuselage shroud 106. For example, referring now to fig. 12 and 13, in certain exemplary embodiments, the fuselage shroud 106 may include a plurality of zones arranged along a circumference of the fuselage 102 such that the impact resistance of the fuselage shroud 106 varies between each adjacent zone along the circumference of the fuselage 102.

Referring specifically to fig. 12, a front-to-rear cross-sectional view of the fuselage 102 including the fuselage shroud 106 according to an exemplary embodiment of the present disclosure is provided. The depicted exemplary fuselage shroud 106 may be configured in a similar manner as the exemplary first fuselage shroud 106 described above, or may be configured in any other suitable manner.

The exemplary fuselage shroud 106 of fig. 12 includes a first zone 164 having a first impact resistance and a second zone 166 having a second impact resistance, the first zone 164 and the second zone 166 being arranged along a circumference of the fuselage 102. More particularly, for the embodiment of fig. 12, the fuselage shroud 106 also includes a third region 168 having a third impact resistance. The second zone 166 and the third zone 168 are disposed on opposite sides of the first zone 164 along the circumference of the fuselage 102. The first impact resistance of the first zone 164 of the fuselage shroud 106 is greater than the second impact resistance of the second zone 166, and is also greater than the third impact resistance of the third zone 168.

In particular, for the illustrated embodiment, the variation in impact resistance is at least partially due to the thickness of the plurality of zones. More particularly, for the illustrated embodiment, the first region 164 defines a first thickness 170 that is greater than a second thickness 172 of the second region 166 and greater than a third thickness 174 of the third region 168. When the fuselage shroud 106 is constructed according to one or more of the above exemplary embodiments (such as the embodiment of fig. 4, where the fuselage shroud 106 includes multiple layers), the configuration of fig. 12 may facilitate the outer layer (e.g., the energy distribution layer 116), the intermediate layer (e.g., the energy absorption layer 118), and/or the inner layer (e.g., the load spreading layer 114) of the first zone 164 being thicker than the respective layers of the second zone 166 and/or the third zone 168.

Notably, for the embodiment of fig. 12, the different regions of the fuselage shroud 106 are integrally formed as a single fuselage shroud 106. However, in other embodiments, the fuselage shroud 106 may have other configurations. Further, for the illustrated embodiment, it will be appreciated that the first, second, and third zones 164, 166, 168 each define a respective span angle 176A, 176B, 176C (measured in the same manner as the span angle 164 of the first fuselage shroud 106 is measured in fig. 11). In fig. 12, the span angles 176A, 176B, 176C are approximately equal to each other. However, in other embodiments, the span angles 176A, 176B, 176C may vary between the zones 164, 166, 168. For example, in certain exemplary embodiments, each of the zones 164, 166, 168 may define a span angle 176A, 176B, 176C equal to at least 10% of the total span angle 162 of the first airframe shroud 106 and up to 80% of the total span angle 162 of the first airframe shroud 106.

For example, referring now to fig. 13, a cross-sectional view looking from the front to the rear of a fuselage 102 including a fuselage shroud 106 according to another exemplary embodiment of the present disclosure is provided. The exemplary fuselage shroud 106 of fig. 13 also includes a plurality of zones arranged along the circumference of the fuselage 102, with the impact resistance of the fuselage shroud 106 varying between adjacent zones. In the illustrated embodiment, the plurality of zones includes at least four zones and up to 10 zones. In particular, for the illustrated embodiment, the plurality of zones includes five zones (first zone 164, second zone 166, third zone 168, fourth zone 178, and fifth zone 180). Although not labeled, the thickness of the fuselage shroud 106 varies between each adjacent zone (e.g., adjacent zones 164 and 166, and adjacent zones 166 and 178). For the embodiment of fig. 13, each adjacent zone is configured as a separate component that may be separately attached to the fuselage 102 or, alternatively, may be attached to each other prior to attachment to the fuselage 102.

It will be appreciated that while the embodiments of fig. 12 and 13 provide different impact resistance between adjacent regions, at least in part, by varying the thickness of the respective adjacent regions, in other embodiments, different impact resistance between adjacent regions may be provided in any other suitable manner. For example, in other embodiments, different impact resistances between adjacent regions may be provided by material selection, relative layer thicknesses, combinations thereof, and the like. In this manner, it will be appreciated that, in other exemplary embodiments, the fuselage shroud 106 may define multiple zones having different impact resistances between adjacent zones while maintaining a relatively constant thickness between adjacent zones. This may be desirable for, for example, aerodynamic reasons, aesthetic reasons, etc.

As will be appreciated, including a body shroud 106 having different zones and adjacent zones having different impact resistances may allow the body shroud 106 to be customized to suit the coverage desired/required by a particular gas turbine engine (including the position of the gas turbine engine relative to the through-body 102, the spacing of the gas turbine engine relative to the body 102, the direction of rotation of the rotor assembly 12 of the gas turbine engine, etc.). In this manner, the fuselage shroud 106 may not add more weight, air resistance, etc. than necessary to provide the desired/required impact resistance for the fuselage 102.

Further, it will be appreciated that while the exemplary zones described above are disposed along a circumference of the fuselage 102, it will be appreciated that, in certain exemplary embodiments, one or more of the zones may also be disposed along a longitudinal direction L1 of the aircraft 100 (e.g., along the length 110 of the fuselage shroud 106; see FIG. 3).

Further, it will be appreciated that, although in certain exemplary embodiments, the exemplary body shroud 106 described above may be configured (except as otherwise described) in a similar manner as the exemplary first body shroud 106 described above, in other embodiments, the body shroud 106 may be configured in any other suitable manner. For example, in certain exemplary embodiments, the fuselage shroud 106 may not include three layers, but may include only two layers, or alternatively may include any other suitable number of layers (e.g., one, four, five, six, or more layers).

Further, as mentioned above, the first and second fuselage shrouds 106, 108 may be attached to the fuselage 102 or integrally formed with the fuselage 102. For example, in certain exemplary embodiments, the first fuselage shroud 106, the second fuselage shroud 108, or both may be welded to the fuselage 102 or otherwise non-removably formed integrally with the fuselage 102.

However, in other exemplary embodiments, it will be appreciated that the first fuselage shroud 106, the second fuselage shroud 108, or both may be removably coupled to the fuselage 102. For example, referring now to fig. 14, a plan view of a fuselage shroud 106 according to yet another exemplary embodiment of the present disclosure is depicted attached to the fuselage 102. The fuselage shroud 106 may be constructed in a similar manner as the example first fuselage shroud 106 described above, or alternatively may be constructed in any other suitable manner.

For the illustrated embodiment, the fuselage shroud 106 is removably coupled to the fuselage 102. As with the above embodiments, the fuselage shroud 106 depicted in FIG. 14 may be removably coupled to the fuselage 102 at a location aligned with the first stage rotor blades of the unducted rotor assembly of the gas turbine engine in the lateral direction of the aircraft.

For the illustrated embodiment, the fuselage shroud 106 is removably coupled to the fuselage 102 using a plurality of mechanical fasteners 138. Additionally, the fuselage shroud 106 includes a plurality of openings 136, and a corresponding plurality of mechanical fasteners 138 may extend through the openings 136 to couple the fuselage shroud 106 to the fuselage 102.

More particularly, referring also briefly to the reference circle 14, the plurality of openings 136 of the fuselage shroud 106 may be configured as a plurality of countersunk screw openings for receiving correspondingly shaped screws or other mechanical fasteners that are countersunk into the fuselage shroud 106 to reduce or eliminate the aerodynamic drag generated by the mechanical fasteners 138.

However, it will be appreciated that, in other exemplary embodiments, the fuselage shroud 106 may be attached to the fuselage 102 in any other suitable manner using any other suitable mechanical fasteners 138 or other fastening devices. For example, in other embodiments, the fuselage shroud 106 may be attached entirely by a plurality of mechanical fasteners 138 (such as one or more countersunk screws, bolts, etc.), or by some combination of mechanical fasteners 138, features attached to or formed with the fuselage 102, glue, epoxy, etc.

Still referring to fig. 14, it will be appreciated that the fuselage shroud 106 defines a perimeter 182 (an area extending around the outermost edge of the fuselage shroud 106, closer to the outermost edge than the center), and the fuselage shroud 106 is removably coupled to the fuselage 102 using a plurality of fasteners (or more particularly, a plurality of mechanical fasteners 138) arranged at a density of at least one fastener per inch and up to twenty-five (25) fasteners per inch. Such a configuration may ensure that the fuselage shroud 106 is coupled to the fuselage 102 in a manner that prevents airflow from passing between the fuselage shroud 106 and the fuselage 102, thereby creating excessive drag on the aircraft.

Further, it will be appreciated that the fuselage shroud 106 includes additional features to reduce drag on the aircraft when the fuselage shroud 106 is coupled to the fuselage 102 of the aircraft. For example, referring now to fig. 15, a cross-sectional view of the exemplary fuselage shroud 106 and fuselage 102 of fig. 14 is depicted. As shown, the fuselage shroud 106 extends between the forward end 184 and the aft end 186 along the longitudinal direction L1. The forward end 184 of the fuselage shroud 106 defines a forward tapered portion 188, the forward tapered portion 188 having a forward taper angle 190 of at least one (1) degree and up to fifteen (15) degrees with the fuselage 102. In particular, for the illustrated embodiment, the front end taper angle 190 of the front end 184 is less than or equal to seven (7) degrees. Similarly, for the illustrated embodiment, the aft end 186 defines an aft end taper 192, the aft end taper 192 having an aft end taper angle 194 with the fuselage 102 of at least one (1) degree and up to fifteen (15) degrees, such as up to seven (7) degrees. The inclusion of the forward and aft tapers 188, 192 may reduce aerodynamic drag on an aircraft by including the fuselage shroud 106.

Further, for the depicted exemplary embodiment, the fuselage shroud 106 includes multiple layers. In particular, for the illustrated embodiment, the fuselage shroud 106 includes a first/outer layer (e.g., energy distribution layer 116), a second/intermediate layer (e.g., energy absorption layer 118), and a third/inner layer (e.g., load spreading layer 114). Further, as mentioned above, the exemplary fuselage shroud 106 is removably coupled to the fuselage 102 using a plurality of mechanical fasteners 138. For the illustrated embodiment, the fuselage shroud 106 is more particularly removably coupled to the fuselage 102 through a first/outer layer using mechanical fasteners 138. Notably, the mechanical fasteners 138 also extend through the third/inner layer.

In this manner, it will be appreciated that the outer, intermediate and inner layers may be coupled to one another using mechanical fasteners 138. Further, for the depicted embodiment, the fuselage shroud 106 defines a joint 196 between the outer and inner layers. For the illustrated embodiment, the joint 196 is a weld joint that attaches the outer and inner layers to each other and couples the fuselage shrouds 196 together.

However, in other embodiments, the first layer, the intermediate layer, and the third layer may be coupled to one another at least in part using any other suitable means, such as by mechanical clamps, resin bonding, compression wrapping, weld joints, lamination, or combinations thereof.

Still referring to fig. 15, it will also be appreciated that for the illustrated embodiment, the intermediate layer is completely enclosed within the interior 198 of the fuselage shroud 106. More particularly, for the illustrated embodiment, the intermediate layer is completely enclosed between the outer and inner layers, with the interior 198 being defined by the outer and inner layers. More particularly, also for the illustrated embodiment, the intermediate layer is hermetically sealed within the interior 198 of the fuselage shroud 106, or more particularly, between the outer and inner layers.

As will be appreciated, configuring the fuselage shroud 106 such that the various layers are coupled to one another, and further such that an intermediate layer (e.g., the energy absorbing layer 118) is hermetically sealed within the interior of the fuselage shroud 106, may further facilitate the fuselage shroud 106 being a removable fuselage shroud 106. More particularly, one or more of such features may allow the fuselage shroud to be installed on an aircraft without requiring additional process steps or integration with the aircraft to ensure that the energy absorbing layer 118 is hermetically sealed from the outside airflow. For example, when the energy absorbing layer 118 defines a relatively low percent solidity, this may be desirable so that if not hermetically sealed, airflow may flow thereto, thereby causing additional drag on the aircraft.

Referring now to fig. 16, a method 200 of replacing a first fuselage shroud on an aircraft is provided. In certain exemplary aspects, the method 200 of fig. 16 may use one or more of the exemplary fuselage shrouds described above with reference to fig. 3-15. For example, the method 200 of fig. 16 may use a fuselage shroud configured to be removably coupled to a fuselage of the aircraft at a location aligned with a primary rotor blade of an unducted rotor assembly of the engine in a lateral direction of the aircraft.

As depicted in fig. 16, the method 200 includes detaching the first fuselage shroud from the fuselage of the aircraft at (202). In the exemplary aspect depicted, disengaging (202) the first fuselage shroud includes removing (204) from the first fuselage shroud one or more fasteners extending from the first fuselage shroud to the fuselage. The one or more fasteners may be mechanical fasteners, such as screws, bolts, etc., and may also be countersunk into the first fuselage shroud. Accordingly, it will be appreciated that in at least certain exemplary aspects, such as the depicted exemplary aspects, removing (204) the one or more fasteners extending from the first body shroud to the fuselage from the first body shroud includes rotating (206) the one or more fasteners in a loosening direction to disengage the first body shroud from the fuselage. This may facilitate "unscrewing" the fastener from the fuselage. However, any other suitable rotatably engaging fastener or other type of fastener may alternatively be used.

Still referring to fig. 16, the method 200 includes removing (208) a first fuselage shroud from a coverage area of a fuselage of the aircraft and placing (210) a second fuselage shroud over at least a portion of the coverage area of the fuselage of the aircraft. The second body hood may be configured in the same manner as the first body hood, or alternatively, the second body hood may be configured differently from the first body hood. For example, the second fuselage shroud may have a different size, shape, thickness, impact resistance, energy absorbing layer material/structure, and the like. This may facilitate relatively easy increase or decrease of the coverage/protection level of a particular fuselage during the lifetime of the aircraft.

Referring also to fig. 16, the method 200 includes coupling the second fuselage shroud to a fuselage of the aircraft using one or more fasteners extending from the first fuselage shroud to the fuselage at (212). In certain exemplary aspects, coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners at (212) includes rotating one or more fasteners in a tightening direction at (214) to couple the first fuselage shroud to the fuselage. In this way, it will be appreciated that the one or more fasteners used to couple the second fuselage shroud to the fuselage may be the same one or more fasteners, or at least the same type of fasteners, that previously coupled the first fuselage shroud to the fuselage of the aircraft.

Notably, in certain exemplary aspects, the second fuselage shroud may include a first layer and a second layer hermetically sealed within an interior of the second fuselage shroud. For such exemplary aspects, coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners at (212) may further comprise coupling the first fuselage shroud to the fuselage of the aircraft using one or more fasteners extending through the first layer at (216).

Further aspects of the invention are provided by the subject matter of the following clauses:

an aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising: a body; a single unducted rotor engine mounted at a location spaced from the fuselage of the aircraft, the single unducted rotor engine comprising an unducted rotor assembly having a single pole rotor blade; and a fuselage shroud attached to or integrally formed with the fuselage at a location aligned in a lateral direction with the single stage rotor blades of the unducted rotor assembly.

The aircraft of one or more of these clauses further comprising: a wing extending from the fuselage generally in a transverse direction, wherein the engine is mounted to the wing.

The aircraft according to one or more of these clauses wherein the engine is a first engine, wherein the fuselage shroud is a first fuselage shroud attached to or integrally formed with a first side of the fuselage, and wherein the aircraft further comprises: a second engine including an unducted rotor assembly having a single stage rotor blade; a first wing extending generally in a transverse direction from a first side of the fuselage, wherein the first engine is mounted to the first wing; a second wing extending generally in a transverse direction from a second side of the fuselage, wherein the second engine is mounted to the second wing; and a second fuselage shroud attached to or integrally formed with the second side of the fuselage at a second location aligned in the lateral direction with the single-stage rotor blades of the second unducted rotor assembly.

The aircraft according to one or more of these clauses, wherein the first fuselage shroud is asymmetrically positioned relative to the second fuselage shroud with respect to a reference plane extending through the center of the aircraft in the longitudinal direction and the vertical direction.

The aircraft according to one or more of these clauses wherein the rotor assembly of the first engine and the rotor assembly of the second engine each rotate in the same direction of rotation, and wherein the first fuselage shroud extends higher in the vertical direction than the second fuselage shroud or extends lower in the vertical direction than the second fuselage shroud.

The aircraft according to one or more of these clauses wherein the first fuselage shroud defines a first absolute positioning angle relative to a top of a vertical reference line extending through a center of the fuselage, wherein the second fuselage shroud defines a second absolute positioning angle relative to the top of the vertical reference line, wherein a difference between the first absolute positioning angle and the second absolute positioning angle is greater than 5 degrees and less than 50 degrees.

The aircraft according to one or more of these clauses wherein the fuselage shroud defines a top end and a bottom end along a vertical direction of the aircraft, wherein the fuselage shroud defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

The aircraft of one or more of these clauses wherein the fuselage shroud comprises a first zone having a first impact resistance and a second zone having a second impact resistance, wherein the first zone and the second zone are arranged along a circumference of the fuselage.

The aircraft of one or more of these clauses wherein the fuselage shroud further comprises a third zone having a third impact resistance, wherein the second zone and the third zone are disposed on opposite sides of the first zone along the circumference of the fuselage, and wherein the first impact resistance is greater than the second impact resistance and greater than the third impact resistance.

The aircraft according to one or more of these clauses wherein the fuselage shroud comprises a plurality of zones arranged along the circumference of the fuselage, wherein the impact resistance of the fuselage shroud varies between each of the adjacent zones.

The aircraft according to one or more of these clauses wherein the thickness of the fuselage shroud varies between each of the adjacent zones.

The aircraft according to one or more of these clauses wherein the plurality of zones comprises at least 4 zones and up to 10 zones.

The aircraft of one or more of these clauses wherein the fuselage shroud defines a surface area of between 720 square inches and 15,000 square inches.

A fuselage shroud assembly for use with a fuselage of an aircraft having an engine, the aircraft defining a longitudinal direction and a lateral direction, the fuselage shroud assembly comprising: a body configured to be attached to or integrally formed with a fuselage of an aircraft at a location aligned with the engines in a lateral direction, the body comprising a plurality of zones configured to be arranged along a circumference of the fuselage when coupled to the fuselage of the aircraft, wherein an impact resistance of the fuselage shroud varies between each of the adjacent zones.

The fuselage shroud assembly of one or more of these clauses, wherein the plurality of zones includes a first zone having a first impact resistance and a second zone having a second impact resistance, wherein the first zone and the second zone are configured to be arranged along a circumference of the fuselage.

The fuselage shroud assembly of one or more of these clauses, wherein the fuselage shroud further comprises a third zone having a third impact resistance, wherein the second zone and the third zone are disposed on opposite sides of the first zone, and wherein the first impact resistance is greater than the second impact resistance and greater than the third impact resistance.

The fuselage shroud assembly according to one or more of these clauses, wherein the thickness of the fuselage shroud varies between each of the adjacent zones.

The fuselage shroud assembly according to one or more of these clauses, wherein the plurality of zones comprises at least 4 zones and up to 10 zones.

The fuselage shroud assembly of one or more of these clauses wherein the fuselage shroud defines a surface area of between 720 square inches and 15,000 square inches.

The fuselage shroud assembly of one or more of these clauses, wherein the body of the fuselage shroud assembly, when coupled to the fuselage of the aircraft, defines a top end and a bottom end in a vertical direction of the aircraft, wherein the body, when coupled to the fuselage of the aircraft, defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

An aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising: a body; an unducted rotor engine mounted at a location spaced from the fuselage of an aircraft, the unducted rotor engine comprising an unducted rotor assembly having a primary unducted rotor blade; and a fuselage shroud removably coupled to the fuselage at a location aligned in a lateral direction with the primary rotor blades of the unducted rotor assembly.

An aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising: a body; an engine mounted at a location spaced from a fuselage of the aircraft, the engine including rotor blades; and at least one fuselage shroud removably coupled to the fuselage at a location aligned with the rotor blades in the lateral direction.

The aircraft of one or more of these clauses wherein the fuselage shroud is removably coupled to the fuselage using a plurality of mechanical fasteners.

The aircraft according to one or more of these clauses wherein the fuselage shroud defines a perimeter, and wherein the fuselage shroud is removably coupled to the fuselage with a plurality of fasteners arranged at a density of at least one fastener per inch and up to 25 fasteners per inch.

The aircraft according to one or more of these clauses wherein the fuselage shroud defines a forward end and an aft end, wherein the forward end defines a forward end cone angle of at least 1 degree and up to 15 degrees.

The aircraft of one or more of these clauses wherein the nose taper angle of the nose is less than or equal to 7 degrees.

The aircraft of one or more of these clauses wherein the aft end defines an aft end cone angle of at least 1 degree and up to 15 degrees.

The aircraft according to one or more of these clauses wherein the fuselage shroud comprises a first layer and a second layer.

The aircraft according to one or more of these clauses wherein the second layer is hermetically sealed within the interior of the fuselage shroud.

The aircraft according to one or more of these clauses wherein the fuselage shroud is removably coupled to the fuselage by a first layer.

The aircraft of one or more of these clauses wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer.

The aircraft according to one or more of these clauses wherein the unducted rotor engine is an engine, and wherein the unducted rotor assembly and the unducted rotor blade of that stage are a single unducted rotor assembly and a single unducted rotor blade, respectively.

The aircraft of one or more of these clauses wherein the fuselage shroud defines a surface area of between 720 square inches and 15,000 square inches.

The aircraft according to one or more of these clauses wherein the fuselage shroud assembly defines a top end and a bottom end in a vertical direction of the aircraft, wherein the fuselage shroud defines a span angle of coverage between the top end and the bottom end as measured from a center of the fuselage of at least 45 degrees and up to about 180 degrees.

An aircraft defining a longitudinal direction and a transverse direction, the aircraft comprising: a body; an unducted rotor engine mounted at a location spaced from the fuselage of an aircraft, the unducted rotor engine comprising an unducted rotor assembly having a primary unducted rotor blade; and a fuselage shroud attached to or integrally formed with the fuselage at a location aligned in a lateral direction with the single stage rotor blades of the unducted rotor assembly, the fuselage shroud including a first layer defining a first density and a second layer defining a second density, the first density being different than the second density.

The aircraft of one or more of these clauses wherein the thickness of the first layer is different than the thickness of the second layer.

The aircraft of one or more of these clauses wherein the first layer is an energy distribution layer and wherein the second layer is an energy absorption layer.

The aircraft of one or more of these clauses wherein the first layer has a thickness of at least 0.05 inches and up to 2.5 inches, and wherein the second layer has a thickness of at least 0.25 inches and up to 4 inches.

The aircraft of one or more of these clauses further comprising a third layer, wherein the third layer is a load spreading layer, and wherein the third layer has a thickness of at least 0.05 inches and up to 2.5 inches.

The aircraft of one or more of these clauses wherein the first layer is formed from kevlar, metal, carbon fiber composite, ceramic, or a combination thereof, and wherein the second layer comprises a honeycomb, a mesh, a foam, a polyurethane material, or a combination thereof.

The aircraft of one or more of these clauses wherein the first density is greater than the second density.

The aircraft of one or more of these clauses wherein the first density is at least about 100% greater than the second density.

The aircraft according to one or more of these clauses wherein the energy distribution layer is located closer to the stage unducted rotor blade than the energy absorption layer.

The aircraft of one or more of these clauses wherein the fuselage shroud further comprises a load distribution layer defining a third density, wherein the third density is greater than the first density.

The aircraft according to one or more of these clauses wherein the energy distribution layer is positioned closer to the stage of unducted rotor blade than the energy absorbing layer, and wherein the energy absorbing layer is positioned closer to the stage unducted rotor blade than the load spreading layer.

The aircraft according to one or more of these clauses wherein the second layer is hermetically sealed within the interior of the fuselage shroud.

The aircraft according to one or more of these clauses wherein the fuselage shroud is coupled to the fuselage by a first layer.

The aircraft of one or more of these clauses wherein the first layer and the second layer are secured to each other at least in part using mechanical clamps, resin bonding, compression wrapping, weld joints, lamination, or a combination thereof.

The aircraft of one or more of these clauses wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer, and wherein the second layer is formed by a plurality of panels and a plurality of spacers positioned between adjacent panels of the plurality of panels.

A fuselage shroud assembly for use with a fuselage of an aircraft having an unducted rotor engine, the aircraft defining a longitudinal direction and a transverse direction, the fuselage shroud assembly comprising: a body formed from a plurality of layers and configured to be attached to or integrally formed with a fuselage of the aircraft at a location aligned with the unducted rotor engine in a lateral direction, the plurality of layers including a first layer and a second layer, the first layer defining a first density and the second layer defining a second density, the first density being different than the second density.

The fuselage shroud assembly of one or more of these clauses wherein the first layer is an energy distribution layer, wherein the second layer is an energy absorption layer, and wherein the first density is greater than the second density.

The fuselage shroud assembly of one or more of these clauses wherein the first density is at least about 100% greater than the second density.

The airframe shroud assembly as recited in one or more of these clauses, wherein the energy distribution layer is configured to be positioned closer to the unducted rotor engine than the energy absorption layer.

The airframe shroud assembly as recited in one or more of these clauses, wherein the airframe shroud further comprises a load spreading layer defining a third density, wherein the third density is greater than the first density, wherein the energy distribution layer is configured to be positioned closer to the unducted rotor engine than the energy absorption layer, and wherein the energy absorption layer is configured to be positioned closer to the unducted rotor engine than the load spreading layer.

The aircraft of one or more of these clauses in combination with the fuselage shroud assembly of one or more of these clauses.

The fuselage shroud assembly according to one or more of these clauses incorporated into the aircraft according to one or more of these clauses.

A method of replacing a first fuselage shroud on an aircraft, the method comprising: detaching the first body shield from a fuselage of the aircraft, wherein detaching the first body shield comprises removing one or more fasteners from the first body shield that extend from the first body shield to the fuselage; removing a first fuselage shield from a coverage area of a fuselage of the aircraft; placing a second fuselage shield over at least a portion of a coverage area of a fuselage of the aircraft; and coupling the second fuselage shroud to a fuselage of the aircraft using one or more fasteners extending from the first fuselage shroud to the fuselage.

The method of one or more of these clauses wherein removing from the first body hood one or more fasteners extending from the first body hood to the fuselage comprises rotating the one or more fasteners in a loosening direction to disengage the first body hood from the fuselage.

The method of one or more of these clauses, wherein coupling the second fuselage shroud to the fuselage of the aircraft using the one or more fasteners comprises rotating the one or more fasteners in a tightening direction to couple the first fuselage shroud to the fuselage.

The method of one or more of these clauses wherein the one or more fasteners comprise a plurality of mechanical fasteners.

The method of one or more of these clauses wherein the second fuselage shroud comprises a first layer and a second layer.

The method of one or more of these clauses wherein the second layer is hermetically sealed within the interior of the second fuselage shroud.

The method of one or more of these clauses wherein coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners comprises coupling the second fuselage shroud to the fuselage of the aircraft using one or more fasteners extending through the first layer.

A method, comprising: placing a fuselage shield on an exterior of a fuselage of the aircraft; and securing the fuselage shroud to the exterior of the fuselage using fasteners.

The method of one or more of these clauses wherein the fuselage cover is a first fuselage cover, and wherein the method further comprises: placing a second fuselage shield on the exterior of the fuselage of the aircraft adjacent the first fuselage shield to form a continuous fuselage shield that protects the exterior of the fuselage; and securing the second fuselage shroud to the exterior of the fuselage using fasteners.

The method of one or more of these clauses wherein the first fuselage shroud, the second fuselage shroud, or both are secured using a fastener adapted to be separated from the first fuselage shroud, the second fuselage shroud, or both and the fuselage of the aircraft to allow the first fuselage shroud, the second fuselage shroud, or both to be replaced with a replacement shroud without affecting the exterior of the fuselage.

The aircraft according to one or more of these clauses, wherein the aircraft is a narrow body aircraft or a wide body aircraft.

The aircraft according to one or more of these clauses, wherein the fuselage of the aircraft defines a width in the lateral direction of at least 80 inches, such as at least 90 inches, such as at least 100 inches, such as at least 110 inches, such as at least 130 inches.

The aircraft according to one or more of these clauses, wherein the fuselage of the aircraft defines a width in the lateral direction of up to 400 inches, or up to 350 inches, or up to 300 inches.

The aircraft according to one or more of these clauses, wherein the plurality of rotor blades define a diameter of at least six feet, such as at least eight feet, such as at least ten feet, such as at least twelve feet.

The aircraft according to one or more of these clauses, wherein the plurality of rotor blades define a diameter of up to 22 feet.

The aircraft according to one or more of these clauses, which is configured to carry more than 100 passengers.

The aircraft according to one or more of these clauses, which is configured to carry more than 150 passengers.

The aircraft according to one or more of these clauses, which is configured to carry less than 600 passengers.

The aircraft of one or more of these clauses having a cruising speed between mach 0.5 and mach 0.85.

The aircraft of one or more of these clauses having a cruising speed between mach 0.75 and mach 0.85.

The aircraft of one or more of these clauses having a cruising altitude of between 28,000 feet and 65,000 feet.

The aircraft of one or more of these clauses having a cruising altitude of between 28,000 feet and 45,000 feet.

The aircraft of one or more of these clauses having a cruising altitude of between about 4.85 and about 0.82 pounds per square inch based on a sea level pressure of about 14.70 pounds per square inch and a sea level temperature of about 59 degrees fahrenheit.

The aircraft of one or more of these clauses having a cruising altitude of between about 4.85 and about 2.14 pounds per square inch based on a sea level pressure of about 14.70 pounds per square inch and a sea level temperature of about 59 degrees fahrenheit.

The aircraft according to one or more of these clauses in combination with the fuselage shroud assembly according to one or more of these clauses and/or for use or in the method according to one or more of these clauses.

The fuselage shroud assembly according to one or more of these clauses incorporated into and/or used in the aircraft according to one or more of these clauses or for the method according to one or more of these clauses.

The method according to one or more of these clauses, using or for an aircraft according to one or more of these clauses and/or a fuselage shroud assembly according to one or more of these clauses.