Auxiliary power unit housing and manufacturing method thereof

Abstract

An auxiliary power unit housing and a method of manufacturing the same are disclosed. The auxiliary power unit housing of the aircraft includes a space frame configured to carry a load and define an auxiliary power unit compartment. The space frame includes a plurality of frame elements coupled together at a plurality of nodes. The auxiliary power unit housing also includes a fairing coupled to the space frame and surrounding the space frame.

Description

Technical Field

[0001] The present disclosure relates generally to airframe assemblies of aircraft, and more particularly, to an auxiliary power unit housing integrated into the airframe of the aircraft. Background Art

[0002] The fuselage of an aircraft is a mechanical structure that typically forms the fuselage, tail, and wings of the aircraft. The fuselages of most modern aircraft are manufactured using monocoque or semi-monocoque fuselage assemblies. An auxiliary power unit (APU) is a device on an aircraft that provides energy for functions other than propulsion. As an example, an APU typically includes a gas turbine engine that operates when the main propulsion engine is not working to provide various power inputs and / or supplement the power generated during the operation of the main engine. The APU is typically located in an isolated portion of the fuselage that is separated from other areas (usually referred to as an APU compartment). The portion of the fuselage that forms the APU compartment must be able to withstand the heat generated during normal operation of the APU and the extreme temperatures caused by failures of the APU (e.g., thermal events in the APU compartment). Therefore, it is desirable to form a housing around the APU to protect the fuselage from the thermal effects of thermal events and to maintain a housing for a thermal suppression system. Conventional practice is to use support brackets to connect insulation blankets to the interior of the fuselage. However, the use of insulation blankets and associated support brackets increases the weight, cost, and production time of the aircraft. Therefore, those skilled in the art continue to engage in research and development in the field of APU housings, and therefore, devices and methods aimed at solving the above-mentioned problems would be useful. Summary of the invention

[0003] The following is a non-exhaustive list of examples of subject matter according to the present disclosure, which may or may not be claimed.

[0004] In an example, an auxiliary power unit housing of an aircraft is disclosed that includes a space frame configured to carry a load and define an auxiliary power unit compartment. The space frame includes a plurality of frame elements coupled together at a plurality of nodes. The auxiliary power unit housing also includes a fairing coupled to the space frame and surrounding the space frame.

[0005] In an example, a fuselage of an aircraft is disclosed that includes a fuselage and a space frame coupled to the fuselage. The space frame is configured to carry a load and defines an auxiliary power unit compartment for stowing an auxiliary power unit of the aircraft. The space frame includes a plurality of frame elements coupled together at a plurality of nodes. The fuselage also includes a fairing coupled to the space frame and surrounding the space frame.

[0006] In an example, a method of manufacturing an aircraft is disclosed including the steps of: (1) coupling a plurality of annular frame elements and a plurality of longitudinal frame elements together at a plurality of nodes; (2) coupling a plurality of diagonal frame elements to at least one of the plurality of annular frame elements and the plurality of longitudinal frame elements adjacent to the plurality of nodes to form a space frame; (3) coupling a fairing to the space frame; and (4) coupling the space frame to a fuselage to form a fuselage of the aircraft.

[0007] Other examples of the disclosed apparatus, systems, and methods will become apparent from the following detailed description, accompanying drawings, and appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 is a schematic block diagram of an example of an aircraft;

[0009] Figure 2 yes Figure 1 A schematic diagram of an example of an aircraft;

[0010] Figure 3 yes Figure 1 A schematic perspective view of an example of a portion of a fuselage of an aircraft;

[0011] Figure 4 yes Figure 1 A schematic perspective view of an example of an auxiliary power unit housing of a fuselage;

[0012] Figure 5 yes Figure 4 A schematic perspective view of an example of a space frame of an auxiliary power unit housing;

[0013] Figure 6 is a schematic front view of an example of an auxiliary power unit housing;

[0014] Figure 7 yes Figure 6 A schematic front view of an example of a space frame of an auxiliary power unit housing;

[0015] Figure 8 is a schematic elevation view of an example of a portion of a space frame;

[0016] Fig. 9 is a schematic perspective view of an example of a portion of an auxiliary power unit housing;

[0017] Fig.10 yes Figure 1 A schematic front view of an example of an auxiliary power unit housing;

[0018] Fig.11 is a flowchart of an example of a method of manufacturing an aircraft; and

[0019] Fig.12is a flow chart of an exemplary aircraft production and service methodology. DETAILED DESCRIPTION

[0020] The following detailed description refers to the accompanying drawings, which show specific examples of the present disclosure. Other examples with different structures and operations do not depart from the scope of the present disclosure. In different drawings, similar reference numerals may refer to the same features, elements or components.

[0021] Illustrative, non-exhaustive examples are provided below, which may be, but not necessarily claim to protect, the subject matter according to the present disclosure. Reference to "example" herein refers to one or more features, structures, elements, components, characteristics, and / or operating steps described in conjunction with the example being included in at least one embodiment and / or implementation of the subject matter according to the present disclosure. Therefore, the phrases "example," "another example," "one or more examples," and similar language throughout the present disclosure may, but not necessarily refer to, the same example. In addition, the subject matter characterizing any one example may, but not necessarily include the subject matter characterizing any other example. In addition, the subject matter characterizing any one example may, but not necessarily be combined with the subject matter characterizing any other example.

[0022] Overall reference Figure 1 , specifically refer to Figures 2 to 10 , an example of an auxiliary power unit (APU) housing 100 of an aircraft 200 is disclosed. In the example, the APU housing 100 includes a space frame 102. The space frame 102 is configured to carry loads and react to loads (i.e., provide load paths to distribute or transfer loads). The space frame 102 defines or forms an auxiliary power unit (APU) compartment 130. The APU compartment 130 is configured to hold an auxiliary power unit (APU) 222 of the aircraft 200. The space frame 102 includes a plurality of frame elements 124 coupled together at a plurality of nodes 110. The APU housing 100 includes a fairing 104. The fairing 104 is coupled to and surrounds the space frame 102.

[0023] refer to Figures 1 to 3, an example of a fuselage 150 of an aircraft 200 is disclosed. Typically, an APU housing 100 is integrated into the fuselage 150 and / or forms a structural component of the fuselage 150. As used herein, a "structural component" refers to a load-bearing member or active structural element that is configured to carry and / or transfer loads or has the ability to carry and / or transfer loads. In the example, the fuselage 150 includes an airframe 202. The airframe 202 is configured to carry loads (i.e., is a structural component of the fuselage 150). The fuselage 150 also includes a space frame 102. The space frame 102 is coupled to the airframe 202. The space frame 102 is configured to carry loads (i.e., is a structural component of the fuselage 150). The space frame 102 defines or forms an APU compartment 130 for loading an APU 222 of the aircraft 200. The space frame 102 includes a plurality of nodes 110 ( Figure 1 ) are connected together at a plurality of frame elements 124. The fuselage 150 also includes a fairing 104. The fairing 104 is connected to and surrounds the space frame 102.

[0024] Figure 2 An example of an aircraft 200 is shown. In the illustrative example, the aircraft 200 is a fixed-wing aircraft. The aircraft 200 includes a fuselage 150 and a pair of wings 220. Generally, the fuselage 202 forms a central structure of the fuselage 150 and the wings 220. The aircraft 200 also includes a plurality of high-level systems 204, such as, but not limited to, a propulsion system 208, an electrical system 210, a hydraulic system 212, an environmental system 214, and / or a communication system 216. Any number of other systems may also be included. In the example, the APU 222 is a component of or provides power for one or more of the high-level systems 204.

[0025] The fuselage 150 forms the main body of the aircraft 200 and defines an interior 206 that is configured to accommodate a crew, one or more passengers, cargo, and advanced systems 204. In the illustrative example, the fuselage 150 is a generally elongated, cylindrical central structure. The fuselage 150 includes a nose at a forward end and a tail at a rear end. In the example, the APU housing 100 is located near the tail of the fuselage 150 or forms a portion of the tail.

[0026] like Figure 2As shown in the example of the aircraft 200, the APU 222 is located within the APU housing 100 of the fuselage 150. In the example, the APU 222 includes an internal combustion engine (not shown), such as a gas turbine engine, which operates to provide mechanical input to various components such as a generator (not shown). The APU housing 100 provides a containment structure that can maintain its strength in response to heat generated during normal operation of the APU 222 and due to extremely high heat such as that caused by a thermal event occurring within the APU compartment 130 due to a failure of the APU 222 located within the APU housing 100.

[0027] Figure 3 A portion of the fuselage 150 is shown. The APU housing 100 has a longitudinal (lengthwise) axis 114. Typically, the longitudinal axis 114 of the APU housing 100 is aligned with (e.g., coincident with) the longitudinal axis 218 of the airframe 202. In one or more examples, the longitudinal axis 114 of the APU housing 100 defines the longitudinal axis of the space frame 102 and the fairing 104. Throughout this disclosure, the longitudinal axis 114 of the APU housing 100 may, but need not necessarily, refer to the longitudinal axis of the space frame 102 and / or the longitudinal axis of the fairing 104. The APU housing 100 is coupled to an adjacent portion of the airframe 202 to form a portion of the fuselage 150.

[0028] like Figure 3 As shown, in the example, the space frame 102 includes or takes the form of a truss-like structure having a closed cross-sectional shape when viewed along the longitudinal axis 114 and forming an open interior region that at least partially defines the APU compartment 130. Generally, the space frame 102 includes or forms a plurality of triangular units composed of a plurality of frame elements 124 that are connected to each other at joints, which are referred to as a plurality of nodes 110. Therefore, external forces and reactions to those forces are considered to act only at the plurality of nodes 110 and result in tension or compression forces in the plurality of frame elements 124. Therefore, the space frame 102 is an internal structure that provides load capacity for the relevant portion of the fuselage 150 (e.g., the tail).

[0029] Figure 3 A portion of the fairing 104 is depicted removed so that the space frame 102 is more clearly visible. In the example, the fairing 104 has a closed cross-sectional shape viewed along the longitudinal axis 114 that partially surrounds the space frame 102. Thus, the fairing 104 is an external structure that provides a smooth contour to the associated portion of the fuselage 150 and reduces the drag of the fuselage 150.

[0030] like Figure 3As shown in , in an example, the fuselage 202 is a semi-monocoque structure that includes a plurality of frames 228 and an outer skin 224, the outer skin 224 having a plurality of stringers 226 coupled to the outer skin 224. The outer skin 224 and the plurality of stringers 226 are coupled to the plurality of frames 228. In a semi-monocoque fuselage assembly, the plurality of frames 228 (also referred to as bobbins) determine the shape of the fuselage 150 and the loads are at least partially supported by the plurality of stringers 226 of the fuselage 202. In another example, the fuselage 202 is a monocoque structure that includes a plurality of frames 228 and an outer skin 224 coupled to the plurality of frames 228. In a monocoque fuselage assembly, the plurality of frames 228 establish the shape of the fuselage 150 and the loads are supported by the outer skin 224 of the fuselage 202.

[0031] Still reference Figure 3 , the APU housing 100 is coupled to or otherwise structurally integrated with the airframe 202 to form the fuselage 150 (in Figure 3 Only a portion of the airframe 202 and the APU housing 100 are shown to illustrate a portion of the fuselage 150). In an example, one or more of the plurality of frame elements 124 of the space frame 102 of the APU housing 100 is coupled to or otherwise structurally engaged with the plurality of frames 228 and / or the plurality of stringers 226 of the airframe 202 to provide a load path between the APU housing 100 and the airframe 202. In an example, the fairing 104 of the APU housing 100 is integrated with or otherwise engaged with the outer skin 224 of the airframe 202 to provide a smooth profile of the fuselage 150 and reduce drag. In an example, a firewall 230 is located between the airframe 202 and the APU housing 100.

[0032] refer to Figure 1 In the example, the space frame 102 is formed of a first material 126 having a first critical temperature 132. The fairing 104 is formed of a second material 128 having a second critical temperature 134. The second critical temperature 134 is less than the first critical temperature 132. As used herein, a critical temperature refers to a temperature at which a material (e.g., a metallic material or a composite material) exceeds its ultimate strength and no longer provides sufficient load-bearing capacity. In the example, the first material 126 does not exceed its ultimate strength in response to a temperature approaching the first critical temperature 132. In the example, the second material 128 does not exceed its ultimate strength in response to a temperature approaching the second critical temperature 134, however, in response to a temperature approaching the first critical temperature 132, it may exceed its ultimate strength. This critical temperature and ultimate strength difference enables the space frame 102 to withstand thermal events and maintain its load-bearing capacity in response to extreme temperatures within the APU compartment 130, while allowing the fairing 104 to structurally degrade in response to such temperatures.

[0033] In an example, the first critical temperature 132 is at least 500°F (260°C) and the second critical temperature 134 is less than 500°F (260°C). In another example, the first critical temperature 132 is at least 600°F (315°C) and the second critical temperature 134 is less than 600°F (315°C). In another example, the first critical temperature 132 is at least 700°F (350°C) and the second critical temperature 134 is less than 700°F (350°C). In another example, the first critical temperature 132 is at least 800°F (425°C) and the second critical temperature 134 is less than 800°F (425°C). In other examples, depending on the composition of the first material 126, the first critical temperature 132 may be less than 500°F (260°C) or greater than 800°F (425°C).

[0034] A typical thermal event within the APU compartment 130 of the APU housing 100 may reach temperatures between about 500°F (260°C) and about 800°F (425°C) in areas proximate the space frame 102 and the fairing 104. During a thermal event, the space frame 102 (e.g., the plurality of frame elements 124) does not exceed its ultimate strength when subjected to temperatures between about 500°F (260°C) and about 800°F (425°C). Thus, when exposed to such extreme temperatures, the space frame 102 maintains its load-bearing capacity and structural integrity. When exposed to such temperatures, the fairing 104 may exceed its ultimate strength and begin to plastically deform. However, since the fairing 104 does not serve as a primary structural (e.g., load-bearing) component of the fuselage 150, plastic deformation or even failure of the fairing 104 does not affect the structural integrity of the APU housing 100.

[0035] Still reference Figure 1 In an example, the first material 126 of the space frame 102 includes a metal material 136. In an example, the metal material 136 is titanium. Titanium provides a beneficial strength-to-weight ratio for aerospace applications. In another example, the metal material 136 is carbon steel. In another example, the metal material 136 is corrosion resistant steel (CRES). In another example, the metal material 136 is a metal matrix composite. In another example, the metal material 136 is titanium silicon carbide (Ti3SiC2). Other metals, metal alloys, or metal composites are also contemplated for use as the metal material 136 of the space frame 102.

[0036] In an example, the second material 128 of the fairing 104 includes a composite material 138. In an example, the composite material 138 is a fiber-reinforced polymer, such as a carbon fiber-reinforced polymer or a glass fiber-reinforced polymer (e.g., fiberglass). In another example, the second material 128 of the fairing 104 includes a metal material, such as aluminum.

[0037] refer to Figures 4 to 10 In the example, the plurality of frame elements 124 of the space frame 102 include a plurality of ring frame elements 106 (also individually referred to as ring frame elements 106). The plurality of ring frame elements 106 are arranged along the longitudinal axis 114 ( Figure 3 ) are spaced apart from each other. Each of the plurality of annular frame elements 106 defines a circumscribe and is oriented approximately perpendicular to the longitudinal axis 114. The plurality of annular frame elements 106 establishes the shape of at least a portion of the APU housing 100. The plurality of frame elements 124 also include a plurality of longitudinal frame elements 108 (also individually referred to as longitudinal frame elements 108). The plurality of longitudinal frame elements 108 are coupled to the plurality of annular frame elements 106 at a plurality of nodes 110. Each of the plurality of longitudinal frame elements 108 extends along the longitudinal axis 114 and intersects approximately perpendicularly with one or more of the plurality of annular frame elements 106. The plurality of frame elements 124 also include a plurality of diagonal frame elements 112 (also individually referred to as diagonal frame elements 112). At least a portion of the plurality of diagonal frame elements 112 is coupled to at least one of the plurality of annular frame elements 106 and the plurality of longitudinal frame elements 108 adjacent to the plurality of nodes 110. For purposes of this disclosure, the term "node" refers to a center or connection point or area where at least two of the ring frame members 106, longitudinal frame members 108, and / or diagonal frame members 112 intersect or branch. Thus, external forces and reactions to those forces are considered to act only at the plurality of nodes 110 and result in tension or compression forces in one or more of the plurality of ring frame members 106, the plurality of longitudinal frame members 108, and the plurality of diagonal frame members 112. The plurality of diagonal frame members 112 provide redundant load paths through the space frame 102.

[0038] In an example, the plurality of annular frame elements 106 are formed of a first material 126 having a first critical temperature 132. In an example, the plurality of longitudinal frame elements 108 are formed of a first material 126 having a first critical temperature 132. In an example, the plurality of diagonal frame elements 112 are formed of a first material 126 having a first critical temperature 132. In an example, at least one of the plurality of annular frame elements 106, the plurality of longitudinal frame elements 108, and the plurality of diagonal frame elements 112 is formed of a metal material 136 such as titanium.

[0039] Overall reference Figure 3 , and specific reference Figures 4 to 7 In an example, depending on the type of airframe assembly, one or more of the ends of the plurality of longitudinal frame elements 108 of the space frame 102 are coupled to the airframe 202 ( Figure 3) of the space frame 102 and / or one or more of the plurality of frames 228 and / or one or more of the plurality of stringers 226 adjacent to the APU housing 100. This arrangement enables the APU housing 100 to be structurally integrated into the remainder of the fuselage 150 and enables loads to be distributed between the space frame 102 and the fuselage 202 adjacent to the APU housing 100.

[0040] Overall reference Figures 4 to 7 , and specific reference Figure 8 In the example, each of the plurality of diagonal frame elements 112 extends between diagonally opposed pairs of nodes of the plurality of nodes 110 (in Figure 8 10A and 10B, and are collectively identified as diagonally opposed node pairs 110A, 110B). The diagonally opposed node pairs 110A, 110B are formed in longitudinally adjacent pairs (in the plurality of annular frame elements 106). Figure 8 106A and 106B, and collectively identified as longitudinally adjacent pairs of annular frame elements 106A, 106B) and radially adjacent pairs of longitudinal frame elements 108 (in Figure 8 The intersection of the first longitudinal frame element 108A and the second longitudinal frame element 108B, individually indicated in the figure, and collectively identified as the radially adjacent pairs of longitudinal frame elements 108A and 106B. Figure 8 As shown, in the example, one end of the diagonal frame element 112 is coupled to at least one of the first annular frame element 106A and the second longitudinal frame element 108B adjacent to the first node 110B. The opposite end of the diagonal frame element 112 is coupled to at least one of the second annular frame element 106B and the first longitudinal frame element 108A adjacent to the second node 110B. Figure 3 ) This arrangement is repeated to provide redundant load paths between each diagonally opposed pair of nodes 110A, 110B.

[0041] Overall reference Figures 4 to 8 , and specifically refer to Fig. 9 In an example, the ends 140 of the diagonal frame members 112 are coupled to the ring frame members 106 adjacent to the nodes 110. In another example, the ends 140 of the diagonal frame members 112 are coupled to the longitudinal frame members 108 adjacent to the nodes 110. In another example, the ends 140 of the diagonal frame members 112 are coupled to the ring frame members 106 and the longitudinal frame members 108 adjacent to the nodes 110.

[0042] The specific shape, size, and angular orientation of each diagonal frame element 112 depends on various factors, such as the number of annular frame elements 106, the number of longitudinal frame elements 108, the shape and size of the space frame 102, and other factors. In an example, one or more diagonal frame elements 112 include one or more twists around their length. In an example, one or more diagonal frame elements 112 include one or more bends along their length.

[0043] Overall reference Figure 2 and 3 , specific reference Figure 4 and Figure 6 In an example, the fairing 104 may include a plurality of reinforcements 116 and a plurality of skins 118 ( Figure 4 ). The plurality of skins 118 are coupled to the plurality of stiffeners 116 . In an example, the plurality of stiffeners 116 are coupled to at least one of the plurality of annular frame members 106 . In an example, the plurality of skins 118 are coupled to at least one of the plurality of annular frame members 106 . Figure 4 A portion of plurality of stiffeners 116 coupled to a portion of plurality of annular frame members 106 and a portion of plurality of skins 118 separated from plurality of stiffeners 116 and plurality of annular frame members 106 are shown. Figure 6 A portion of the plurality of reinforcements 116 coupled to a portion of the plurality of annular frame members 106 is shown, and the plurality of skins 118 are removed for clarity. In another example, the fairing 104 may include a plurality of skins 118 coupled to at least one of the annular frame members 106 and / or at least one of the longitudinal frame members 108, such as Figure 3 shown.

[0044] Overall reference Figure 3 , specific reference Figure 4 and Figure 6 In an example, depending on the type of fuselage assembly, ends of one or more of the plurality of stiffeners 116 of the fairing are coupled to one or more of the plurality of frames 228 and / or the fuselage 202 ( Figure 3 ) adjacent to the APU housing 100. The edge of one or more of the plurality of skins 118 abuts and engages with an adjacent edge of the outer skin 224 of the fuselage 202. This arrangement enables the APU housing 100 to be aerodynamically integrated into the rest of the fuselage 150.

[0045] In an example, the plurality of reinforcements 116 are formed of a second material 128 having a second critical temperature 134. In an example, the plurality of skins 118 are formed of a second material 128 having a second critical temperature 134. In an example, at least one of the plurality of reinforcements 116 and the plurality of skins 118 is formed of a composite material 138, such as a fiber-reinforced polymer, such as a carbon fiber-reinforced polymer or fiberglass. In an example, the skins 118 are formed of at least one sandwich panel, such as a honeycomb panel or a foam core sandwich panel.

[0046] Overall reference Figures 3 to 7 , and specifically refer to Fig.10 In the example, the APU housing 100 includes a door 122 ( Fig.10 In the example, the space frame 102 includes a plurality of semi-annular frame elements 120 (also individually referred to as semi-annular frame elements 120). The plurality of semi-annular frame elements 120 are arranged along the longitudinal axis 114 ( Figure 3 ) are spaced apart from each other and from the plurality of annular frame elements 106. Each of the plurality of semi-annular frame elements 120 defines a perimeter and is oriented generally perpendicular to the longitudinal axis 114. The plurality of semi-annular frame elements 120 form the shape of a portion of the APU housing 100. The open area 142 ( Figure 4 and Fig.10 ) is configured to accommodate a door 122. The plurality of longitudinal frame elements 108 are coupled to the plurality of semi-circular frame elements 120 at a plurality of nodes 110. Each of the plurality of longitudinal frame elements 108 intersects one or more of the plurality of semi-circular frame elements 120 substantially perpendicularly. A portion of the plurality of diagonal frame elements 112 are coupled to at least one of the plurality of semi-circular frame elements 120 and the plurality of longitudinal frame elements 108 adjacent to the plurality of nodes 110.

[0047] like Fig.10 As shown, in the example, the door 122 is coupled to at least one of the plurality of semi-annular frame elements 120 and / or at least one of the plurality of longitudinal frame elements 108 intersecting the plurality of semi-annular frame elements 120 and at least partially defining the opening area 142 ( Figure 4 The door 122 is movable relative to the plurality of semi-annular frame members 120 and / or the plurality of longitudinal frame members 108 to which it is coupled. The door 122 provides access to the APU compartment 130 ( Figure 3 ) and thus to APU 222 ( Figure 2 ) channel.

[0048] refer to Figures 4 to 7In an example, one or more of the plurality of annular frame elements 106 include a plurality of shear ties 144 (also individually referred to as shear ties 144). The plurality of shear ties 144 are spaced apart from one another and extend around at least a portion of the perimeter of the annular frame element 106. Figure 4 and Figure 6 As best shown, the open areas (commonly referred to as mouse holes) formed between adjacent shear ties 144 receive one of the plurality of longitudinal frame members 108 of the space frame 102 or one of the plurality of stiffeners 116 of the fairing 104. Similarly, in the example, one or more of the plurality of semi-annular frame members 120 include a plurality of shear ties 144 to receive one of the plurality of longitudinal frame members 108 of the space frame 102 and one of the plurality of stiffeners 116 of the fairing 104.

[0049] In an example, at least a portion of the plurality of shear bands 144 is formed of a first material 126 having a first critical temperature 132. As an example, at least a portion of the plurality of shear bands 144 is formed of a metallic material 136, such as titanium. In another example, at least a portion of the plurality of shear bands 144 is formed of a second material 128 having a second critical temperature 134. As an example, at least a portion of the plurality of shear bands 144 is formed of a composite material 138, such as a fiber reinforced polymer, such as a carbon fiber reinforced polymer.

[0050] Overall reference Figures 1 to 10 , and specific reference Fig.11 , discloses an example of a method 1000 for manufacturing an aircraft 200. The aircraft 200 ( Figure 1 and Figure 2 ) includes a fuselage 202 and an APU housing 100, which form at least a portion of a fuselage 150.

[0051] In the example, the method 1000 includes the step of coupling together a plurality of ring frame members 106 and a plurality of longitudinal frame members 108 at a plurality of nodes 110 (block 1002). The method 1000 includes the step of coupling a plurality of diagonal frame members 112 to at least one of the plurality of ring frame members 106 and the plurality of longitudinal frame members 108 adjacent to the plurality of nodes 110 to form the space frame 102 (block 1004).

[0052] In an example, according to the method 1000, the step of coupling the plurality of diagonal frame members 112 to at least one of the plurality of ring frame members 106 and the plurality of longitudinal frame members 108 includes the step (block 1006) of coupling each of the plurality of diagonal frame members 112 between diagonally opposed pairs of nodes of the plurality of nodes 110 formed at intersections of longitudinally adjacent pairs of the plurality of ring frame members 106 and radially adjacent pairs of the plurality of longitudinal frame members 108. According to the method 1000, the step of coupling the plurality of diagonal frame members 112 to at least one of the plurality of ring frame members 106 and the plurality of longitudinal frame members 108 includes the step of providing a plurality of redundant load paths (block 1008).

[0053] In the example, the method 1000 includes the step of coupling the fairing 104 to the space frame 102 (block 1010 ). The method 1000 includes the step of coupling the space frame 102 to the airframe 202 to form the fuselage 150 of the aircraft 200 (block 1012 ).

[0054] In the example, the method 1000 includes the step of loading the APU 222 of the aircraft 200 in the APU compartment 130 defined by the space frame 102 (block 1014). According to the method 1000, the space frame 102 is formed of a first material 126 having a first critical temperature 132, the fairing 104 is formed of a second material 128 having a second critical temperature 134, and the second critical temperature 134 is less than the first critical temperature 132.

[0055] In an example, the method 1000 includes a step of not exceeding an ultimate strength of the first material 126 of the space frame 102 in response to the temperature rising to the first critical temperature 132 (block 1016 ).

[0056] like Fig.12 As shown in the flowchart of FIG. 1 , examples of the APU housing 100, fuselage 150, aircraft 200, and method 1000 may be used in the context of an aircraft manufacturing and maintenance service method 1100. The disclosed example aircraft applications may include the manufacturing, operation, and maintenance of an aircraft including a fuselage compartment configured to carry an auxiliary power unit. Although examples of the APU housing 100 and method 1000 are described in conjunction with aerospace applications, the APU housing 100 and method 1000 may be used in a variety of potential applications, particularly in the transportation industry, and may be used in any type of vehicle that utilizes an auxiliary power unit.

[0057] like Fig.12As shown, during pre-production, the method 1100 may include specification and design of the aircraft 200 (block 1102) and material procurement (block 1104). During production of the aircraft 200, manufacturing of components and subassemblies of the aircraft 200 (block 1106) and system integration (block 1108) may be performed. Thereafter, the aircraft 200 may be certified and delivered (block 1110) to be placed in service (block 1112). The disclosed APU housing 100 and method 1000 may form part of component and subassembly manufacturing (block 1106) and / or system integration (block 1108). Routine maintenance and repair (block 1114) may include modification, reconfiguration, refurbishment, etc. of one or more systems of the aircraft 200.

[0058] Fig.12 Each process of the method 1100 shown may be performed or executed by a system integrator, a third party and / or an operator (e.g., a customer). For ease of illustration, a system integrator may include, but is not limited to, any number of aircraft manufacturers and major system subcontractors; a third party may include, but is not limited to, any number of suppliers, subcontractors, and vendors; an operator may be an airline, a leasing company, a military entity, a service organization, etc.

[0059] exist Fig.12 The examples of the APU housing 100 and method 1000 shown or described herein may be employed during any one or more of the stages of the manufacturing and repair method 1100 shown in the flowchart shown. For example, the manufacturing or production of components or subassemblies such as the space frame 102 and the fairing 104 of the APU housing 100 corresponding to the component and subassembly manufacturing (block 1106) may be similar to the manner in which the components or subassemblies are produced when the aircraft 200 is in service (block 1112). Moreover, one or more examples of the APU housing 100 and method 1000 disclosed herein may be utilized during the production stage (blocks 1108 and 1110). Similarly, one or more examples of the APU housing 100 and method 1000 disclosed herein may be utilized when the aircraft 200 is in service (block 1112) and during maintenance and repair (block 1114), for example but not limitation.

[0060] Although an aerospace example is shown, the principles disclosed herein may be applied to other industries, such as the automotive industry, the aerospace industry, the construction industry, and other design and manufacturing industries. Thus, in addition to aircraft, the principles disclosed herein may be applicable to other vehicle structures (e.g., land vehicles, marine vehicles, spacecraft, etc.) and independent structures.

[0061] As used herein, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is actually able to perform the specified function without any changes, rather than merely having the potential to perform the specified function after further modification. In other words, a system, device, structure, article, element, component, or hardware that is "configured to" perform a specified function is specifically selected, created, implemented, utilized, programmed, and / or designed for the purpose of performing the specified function. As used herein, "configured to" means an existing feature of the system, device, structure, article, element, component, or hardware that enables the system, device, structure, article, element, component, or hardware to perform the specified function without further modification. For the purposes of this disclosure, a system, device, structure, article, element, component, or hardware that is described as "configured to" perform a particular function may be described additionally or alternatively as "suitable for" and / or "operable to" perform that function.

[0062] Unless otherwise indicated, the terms "first", "second", etc. are used herein merely as labels and are not intended to impose order, position, or hierarchy requirements on the items to which these terms refer. In addition, reference to a "second" item does not require or exclude the presence of lower-numbered items (e.g., "first" items) and / or higher-numbered items (e.g., "third" items).

[0063] For the purposes of this disclosure, the terms "coupled," "coupled," and similar terms refer to two or more elements being joined, linked, fastened, connected, communicated, or otherwise associated (e.g., mechanically, electrically, fluidically, optically, electromagnetically). In various examples, the elements may be associated directly or indirectly. As an example, element A may be directly associated with element B. As another example, element A may be indirectly associated with element B, such as via another element C. It will be understood that not all associations between the various elements disclosed must be represented. Therefore, other connections other than those depicted in the figures may also be present.

[0064] As used herein, the phrase "at least one" when used with a list of items means that different combinations of one or more of the listed items may be used, and only one of each item in the list may be required. For example, "at least one of item A, item B, and item C" may include, but is not limited to, item A or item A and item B. This example may also include item A, item B, and item C or item B and item C. In other examples, "at least one" may be, for example, but not limited to, two of item A, one of item B, and ten of item C; four of item B and seven of item C; and other suitable combinations.

[0065] As used herein, the term "approximately" refers to or indicates a situation that is close to but not exactly the described situation that still performs the desired function or achieves the desired result. In the example, the term "approximately" refers to a situation within an acceptable predetermined tolerance or precision. In the example, the term "approximately" refers to a situation within 10% of the described situation. However, the term "approximately" does not exclude a situation that is exactly the described situation. Accordingly, the term "approximately" can be interpreted as precisely meaning the desired precision or within the desired precision.

[0066] In the above mentioned Figure 1 In the diagrams, boxes may represent elements, components, and / or portions thereof, and lines connecting various elements and / or components, if any, may represent mechanical, electrical, fluid, optical, electromagnetic, and other connections, and / or combinations thereof. There may also be connections different from those shown in the block diagrams. One or more of the elements shown may be omitted from the specific examples without departing from the scope of the present disclosure. Environmental elements, if any, are represented by dashed lines. For clarity, virtual (imaginary) elements may also be shown. Those skilled in the art will recognize that Figure 1 Some of the features described in can be combined in various ways without having to include Figure 1 Other features shown, other figures and / or the accompanying disclosure, even if such a combination or multiple combinations are not explicitly shown herein. Similarly, additional features not limited to the examples presented may be combined with some or all of the features shown and described herein.

[0067] In the above mentioned Fig.11 and Fig.12 In the disclosure, the blocks may represent operations and / or parts thereof, and the lines connecting the blocks do not imply any particular order or dependency of the operations or parts thereof. It will be understood that all dependencies between the various disclosed operations are not necessarily represented. Fig.11 and Fig.12 The attached disclosure describing the operation of the disclosed method set forth herein should not be interpreted as necessarily determining the order in which the operations are to be performed. Rather, although an illustrative order is indicated, it should be understood that the order of the operations can be appropriately modified. Therefore, the operations shown can be modified, added and / or omitted, and certain operations can be performed in different orders or simultaneously. In addition, those skilled in the art will understand that it is not necessary to perform all the operations described.

[0068] In addition, the present disclosure includes examples according to the following items:

[0069] 1. An auxiliary power unit housing of an aircraft, comprising:

[0070] a space frame configured to carry a load and define an auxiliary power unit compartment, wherein the space frame comprises a plurality of frame elements coupled together at a plurality of nodes; and

[0071] A fairing is coupled to and surrounds the space frame.

[0072] 2. The auxiliary power unit housing according to claim 1, wherein:

[0073] The space frame is formed of a first material having a first critical temperature;

[0074] The fairing is formed of a second material having a second critical temperature; and

[0075] The second critical temperature is lower than the first critical temperature.

[0076] 3. The auxiliary power unit housing according to claim 2, wherein:

[0077] The first material of the space frame comprises a metal material; and

[0078] The second material of the fairing includes a composite material.

[0079] 4. The auxiliary power unit housing according to claim 3, wherein:

[0080] The metal material comprises at least one of titanium, corrosion-resistant steel and a metal-based composite material; and

[0081] The composite material is a fiber-reinforced polymer.

[0082] 5. The auxiliary power unit housing of clause 1, wherein the plurality of frame elements of the space frame comprises:

[0083] a plurality of annular frame elements spaced apart from one another along a longitudinal axis of the space frame;

[0084] a plurality of longitudinal frame members coupled to the plurality of annular frame members at the plurality of nodes; and

[0085] A plurality of diagonal frame members are coupled to at least one of the plurality of circular frame members and the plurality of longitudinal frame members adjacent the plurality of nodes.

[0086] 6. An auxiliary power unit housing according to item 5, wherein each of the plurality of diagonal frame elements extends between diagonally opposite pairs of nodes of a plurality of nodes, and the diagonally opposite pairs of nodes of the plurality of nodes are formed at the intersection of longitudinally adjacent pairs of a plurality of annular frame elements and radially adjacent pairs of a plurality of longitudinal frame elements.

[0087] 7. An auxiliary power unit housing according to any one of clauses 5 or 6, wherein the fairing comprises:

[0088] a plurality of reinforcement members coupled to at least one of the plurality of annular frame members; and

[0089] A plurality of skins are coupled to the plurality of stiffeners.

[0090] 8. An auxiliary power unit housing according to any one of clauses 5 or 6, further comprising a door, and wherein:

[0091] The space frame further includes a plurality of semi-annular frame elements spaced apart from each other and from the plurality of annular frame elements along a longitudinal axis of the space frame;

[0092] the plurality of longitudinal frame elements are coupled to the plurality of semi-annular frame elements at the plurality of nodes;

[0093] The plurality of diagonal frame elements are coupled to at least one of the plurality of semi-annular frame elements and the plurality of longitudinal frame elements adjacent the plurality of nodes; and

[0094] The door is coupled to and movable relative to the plurality of semi-annular frame elements.

[0095] 9. An aircraft fuselage, comprising:

[0096] Body;

[0097] a space frame coupled to the fuselage, wherein the space frame is configured to carry a load and defines an auxiliary power unit compartment for stowing an auxiliary power unit of the aircraft, and wherein the space frame includes a plurality of frame elements coupled together at a plurality of nodes; and

[0098] A fairing is coupled to and surrounds the space frame.

[0099] 10. The fuselage according to claim 9, wherein the fuselage is a semi-monocoque structure, comprising:

[0100] Outer skin;

[0101] a plurality of stringers coupled to the outer skin; and

[0102] Multiple frames connected to the outer skin.

[0103] 11. The fuselage of clause 9, wherein:

[0104] The space frame is formed of a first material having a first critical temperature;

[0105] The fairing is formed of a second material having a second critical temperature; and

[0106] The second critical temperature is lower than the first critical temperature.

[0107] 12. A fuselage according to claim 11, wherein:

[0108] The first material of the space frame comprises at least one of titanium, corrosion resistant steel, and a metal matrix composite material; and

[0109] The second material of the fairing is a fiber reinforced polymer.

[0110] 13. The fuselage of clause 9, wherein the plurality of frame elements of the space frame comprises:

[0111] a plurality of annular frame elements longitudinally spaced from one another along a longitudinal axis of the space frame;

[0112] a plurality of longitudinal frame members radially spaced from one another about a longitudinal axis of the space frame and coupled to the plurality of annular frame members at a plurality of nodes; and

[0113] A plurality of diagonal frame members are coupled to at least one of the plurality of circular frame members and the plurality of longitudinal frame members adjacent the plurality of nodes.

[0114] 14. A fuselage according to claim 13, wherein each of the plurality of diagonal frame elements extends between diagonally opposed pairs of nodes of a plurality of nodes, the diagonally opposed pairs of nodes of the plurality of nodes being formed at the intersection of longitudinally adjacent pairs of a plurality of annular frame elements and radially adjacent pairs of a plurality of longitudinal frame elements.

[0115] 15. A fuselage according to any one of clauses 13 or 14, wherein the fairing comprises:

[0116] a plurality of reinforcement members coupled to at least one of the plurality of annular frame members; and

[0117] A plurality of skins are coupled to the plurality of stiffeners.

[0118] 16. A fuselage according to any one of clauses 13 or 14, further comprising a door for accessing the auxiliary power unit compartment; and wherein:

[0119] The space frame further includes a plurality of semi-annular frame elements spaced apart from each other and from the plurality of annular frame elements along a longitudinal axis of the space frame;

[0120] a plurality of longitudinal frame members coupled to the plurality of semi-annular frame members at a plurality of nodes;

[0121] a plurality of diagonal frame elements coupled to at least one of the plurality of semi-annular frame elements and the plurality of longitudinal frame elements adjacent the plurality of nodes; and

[0122] The door is coupled to and movable relative to the plurality of semi-annular frame elements.

[0123] 17. A method of manufacturing an aircraft, the method comprising:

[0124] coupling the plurality of annular frame members and the plurality of longitudinal frame members together at a plurality of nodes;

[0125] coupling a plurality of diagonal frame members adjacent the plurality of nodes to at least one of the plurality of annular frame members and the plurality of longitudinal frame members to form a space frame;

[0126] coupling a fairing to the space frame; and

[0127] The space frame is coupled to an airframe to form a fuselage of the aircraft.

[0128] 18. A method according to item 17, wherein the step of connecting the plurality of diagonal frame elements adjacent to the plurality of nodes to at least one of the plurality of annular frame elements and the plurality of longitudinal frame elements comprises: connecting each of the plurality of diagonal frame elements between diagonally opposite pairs of nodes of the plurality of nodes, the diagonally opposite pairs of nodes being formed at the intersection of longitudinally adjacent pairs of the plurality of annular frame elements and radially adjacent pairs of the plurality of longitudinal frame elements.

[0129] 19. A method according to any one of clauses 17 or 18, further comprising stowing an auxiliary power unit of the aircraft in an auxiliary power unit compartment defined by the space frame, and wherein:

[0130] The space frame is formed of a first material having a first critical temperature;

[0131] The fairing is formed of a second material having a second critical temperature; and

[0132] The second critical temperature is lower than the first critical temperature.

[0133] 20. The method of claim 19, further comprising: in response to the temperature in the auxiliary power unit compartment rising to the first critical temperature, not exceeding the ultimate strength of the first material of the space frame

[0134] Although various examples of the disclosed APU housing 100, fuselage 150, aircraft 200, and method 1000 have been shown and described, modifications may occur to one skilled in the art upon reading the specification. The present application includes such modifications and is limited only by the scope of the claims.

Claims

1. An auxiliary power unit housing (100) of an aircraft (200), comprising: A space frame (102) configured to carry a load and define an auxiliary power unit compartment (130), wherein the space frame includes a plurality of frame elements (124) coupled together at a plurality of nodes (110); and a fairing (104) coupled to and surrounding the space frame, in: The space frame (102) is formed of a first material (126) having a first critical temperature (132); The fairing (104) is formed of a second material (128) having a second critical temperature (134); and The second critical temperature is lower than the first critical temperature, The critical temperature is the temperature at which a material exceeds its ultimate strength and ceases to provide sufficient load-bearing capacity. wherein the second material does not exceed its ultimate strength in response to a temperature approaching the second critical temperature, but exceeds its ultimate strength in response to a temperature approaching the first critical temperature, Wherein, the plurality of frame elements (124) of the space frame (102) include: a plurality of annular frame elements (106) spaced apart from one another along a longitudinal axis (114) of the space frame; a plurality of longitudinal frame members (108) coupled to the plurality of annular frame members at the plurality of nodes (110); and A plurality of diagonal frame members (112) are coupled to at least one of the plurality of annular frame members and the plurality of longitudinal frame members adjacent the plurality of nodes.

2. The auxiliary power unit housing (100) according to claim 1, wherein: The first material (126) of the space frame (102) comprises a metal material (136); and The second material (128) of the fairing (104) includes a composite material (138).

3. The auxiliary power unit housing (100) according to claim 2, wherein: The metal material (136) includes at least one of a composite material of titanium and a metal matrix; and The composite material (138) is a fiber-reinforced polymer.

4. The auxiliary power unit housing (100) according to claim 1, wherein: Each of the plurality of diagonal frame elements (112) extends between diagonally opposed pairs of nodes of the plurality of nodes (110) formed at intersections of longitudinally adjacent pairs of the plurality of annular frame elements (106) and radially adjacent pairs of the plurality of longitudinal frame elements (108).

5. The auxiliary power unit housing (100) according to claim 1 or 4, wherein: The fairing (104) comprises: a plurality of reinforcement members (116) coupled to at least one of the plurality of annular frame members (106); and A plurality of skins (118) are coupled to the plurality of stiffeners.

6. The auxiliary power unit housing (100) of claim 1 or 4, further comprising a door (122), and wherein: The space frame (102) further includes a plurality of semi-annular frame elements (120) spaced apart from each other and from the plurality of annular frame elements (106) along the longitudinal axis (114) of the space frame; The plurality of longitudinal frame members (108) are coupled to the plurality of semi-annular frame members at the plurality of nodes (110); The plurality of diagonal frame elements (112) are coupled to at least one of the plurality of semi-annular frame elements and the plurality of longitudinal frame elements adjacent the plurality of nodes; and The door is coupled to and movable relative to the plurality of semi-annular frame elements.

7. A method (1000) of manufacturing an aircraft (200), the method comprising: coupling a plurality of annular frame members (106) and a plurality of longitudinal frame members (108) together at a plurality of nodes (110); coupling a plurality of diagonal frame members (112) adjacent the plurality of nodes to at least one of the plurality of annular frame members and the plurality of longitudinal frame members to form a space frame (102); coupling a fairing (104) to the space frame; and coupling the space frame to a fuselage (202) to form a fuselage (150) of the aircraft, The space frame (102) is formed of a first material (126) having a first critical temperature (132); The fairing (104) is formed of a second material (128) having a second critical temperature (134); and The second critical temperature is lower than the first critical temperature, The critical temperature is the temperature at which a material exceeds its ultimate strength and ceases to provide sufficient load-bearing capacity. wherein the second material does not exceed its ultimate strength in response to a temperature approaching the second critical temperature, but exceeds its ultimate strength in response to a temperature approaching the first critical temperature.

8. The method (1000) according to claim 7, wherein: The step of coupling the plurality of diagonal frame elements (112) adjacent the plurality of nodes (110) to at least one of the plurality of annular frame elements (106) and the plurality of longitudinal frame elements (108) comprises coupling each of the plurality of diagonal frame elements between diagonally opposed pairs of nodes of the plurality of nodes, the diagonally opposed pairs of nodes of the plurality of nodes being formed at intersections of longitudinally adjacent pairs of the plurality of annular frame elements and radially adjacent pairs of the plurality of longitudinal frame elements.

9. The method (1000) of claim 7 or 8, further comprising stowing an auxiliary power unit (222) of the aircraft (200) in an auxiliary power unit compartment (130) defined by the space frame (102).

10. The method (1000) of claim 9, further comprising not exceeding an ultimate strength of the first material (126) of the space frame (102) in response to a temperature within the auxiliary power unit compartment (130) rising to the first critical temperature (132).

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