TECHNICAL FIELD
[0001] The present subject matter relates generally to a monocoque structure for a motor vehicle and more particularly to a monocoque structure for a two-wheeled vehicle.
BACKGROUND
[0002] Generally, a two-wheeled vehicle may have a frame structure, or a monocoque structure that acts as a structural member and bears the load of the vehicle. Typically, a tubular section or castings form the frame structure, which acts as structural member, for bearing loads and for mounting vehicle parts. Plurality of panels covers the frame structure. Whereas, the monocoque structure is integral part of the body, which acts as the structural member, load-bearing member and constitutes of mountings for vehicle parts.
BRIEF DESCRIPTION OF DRAWINGS
[0003] The detailed description of the present subject matter is described with
reference to the accompanying figures. Same numbers are used throughout the
drawings to reference like features and components.
[0004] Fig. 1 illustrates a left side view of an exemplary vehicle, in
accordance with an embodiment of present subject matter.
[0005]. Fig. 2 (a) illustrates a left side perspective view of a monocoque
structure, in accordance with an embodiment of the present subject matter.
[0006] Fig. 2 (b) depicts an enlarged view of a portion of the monocoque
structure depicted in Fig. 2 (a).
[0007] Fig. 3 illustrates an enlarged view of a portion of a monocoque
structure, in accordance with another embodiment of the present subject matter.
[0008] Fig. 4 (a) depicts atop perspective view of a portion of the monocoque
structure, in accordance with the embodiment depicted in Fig. 2 (a).

[0009] Fig. 4 (b) illustrates a cross-sectional view of the monocoque structure
depicted in Fig. 4 (a).
[00010] Fig. 4 (c) depicts a cross sectional view of the side railing in
accordance with the embodiment depicted in Fig. 4 (a).
[00011] Fig. 5 depicts a side railing having a D-shaped cross section, in
accordance with yet another embodiment of the present subject matter.
[00012] Fig. 6 depicts a cross sectional view of a floorboard portion in
accordance with an additional embodiment of the present subject matter.
DETAILED DESCRIPTION
[00013] Generally, a monocoque structure is known in the art with a pair of side railings disposed at extreme lateral ends is known in the art. The side railing(s) may include plurality of sub-side railings. The sub-side railings are made of a rigid material, like metal. Each sub-side railing is in contact with the adjacent sub-railing. Typically, the side railing(s) are major visible portions of the vehicle providing aesthetic appeal and also acting as load bearing members of the vehicle. [00014] With the increase in engine capacity and varying load parameters, there is a need for providing structural strength for the monocoque structure both in -lateral and longitudinal direction. In addition, the monocoque structure is mounted with various loads. For example, the floorboard is mounted with various types of _ loads thereby subjecting' the monocoque structure to stress. Therefore, the monocoque structure known in the art is subject to various loads that would affect the monocoque structure resulting in breakdown, failure, or deformation. Moreover, the monocoque structure being the structural member and body of the vehicle, would affect the performance of the vehicle.
[00015] Thus, there is need for providing a monocoque structure with improved structural rigidity. However, the structural rigidity should be achieved without

decreasing the power to weight ratio of the vehicle. Therefore, load-bearing locations of the monocoque structure that includes floorboard portion are to be provided with load bearing strength/structural rigidity without increasing the weight of the vehicle. Further, structural rigidity is to be provided without affecting the aesthetic appeal of the monocoque structure as the structure acts as body of the vehicle. In addition, the ease of construction and manufacturability is to be considered for providing structural rigidity/strength.
[00016] Hence, an objective of the present subject matter is to overcome the aforementioned and other disadvantages and to provide a monocoque structure that is having improved structural rigidity.
[00017] According to another object of the present subject matter, the monocoque structure is provided with improved structural strength without compromising on power to weight ratio.
[00018] It is a feature of the present subject matter that the sub-railings of the side railings are provided with one end portion at the contact area of the peripheral edges being not in line with another end portion of the contact area of the peripheral edges thereby improving load-bearing area. It is still another feature of the present subject matter that the aesthetic appeal of the monocoque structure is not compromised.
[00019] It is an aspect of the present subject matter that the cross-section of the side railings having a top portion of the cross section being substantially outward with respect to a bottom portion of the cross section thereby enables better banking of the vehicle. It is an additional aspect of the present subject matter that the aforementioned cross section in conjunction with a stiffener plate improves the structural strength. It is still an additional aspect that side railings enhance structural strength in a direction substantially perpendicular to the direction of the load. For example, the structural strength of the floorboard is enhanced by providing stiffener

members in a direction substantially perpendicular to the direction of the load
acting on the floorboard.
[00020] It is an advantage of the present subject matter that the upper portion of
the outer face of the side railing being disposed outward with respect to the lower
portion of the outer face provides sufficient banking angle. Also, the
aforementioned profile of the outer face provides aerodynamic structure to direct
the air, which is advantageous when the vehicle is in motion.
[00021] It is an advantage of the present subject matter that it provides ease of
construction and manufacturability.
[00022] In an embodiment, a vehicle with a monocoque structure is provided that acts as structural member or load bearing member, and body of the vehicle. ■ The monocoque structure extends from a front portion towards a rear portion of the vehicle, which is along the longitudinal direction of the vehicle. Specifically, the monocoque structure extends from a substantially from portion of the vehicle towards a substantially rear portion of the vehicle. In one embodiment, the floorboard extends from below a handle bar assembly towards a tail lamp of the vehicle. However, the aforementioned mentioned structure is not limiting as the monocoque structure is adaptable to the vehicle layout for which it is being implemented.
[00023] In an embodiment, the monocoque structure includes a right side railing and a left side railing disposed at extreme ends in a vehicle width direction, which also forms the style parts of the vehicle. In another embodiment, for a vehicle with step-through space, the pair of railings extends from below a handle bar assembly towards a floorboard portion and then inclinedly rearward from the floorboard portion towards a tail lamp. Further, the monocoque structure includes a-plurality of bridge members connecting the left side railing and the right side railing, and disposed therebetween. A housing panel positioned rearwardly of the

floorboard portion, and supported by at least a portion of the pair of side railing. A floorboard is disposed at a floorboard portion of the vehicle. In an embodiment, a bridge member of the plurality of bridge members supports the floorboard portion.
[00024] In an embodiment, the right side railing includes two or more right side sub-railings and the left side railing includes two or more left side sub-railings. Each of the sub-railing is secured to adjacent sub-railing to form a side railing. For example, the sub-railings are secured by welding, fastening, or any method known in the art.
[00025] In an embodiment, a peripheral edge of one sub-railing is in contact with another peripheral edge of another sub-railing. Furthermore, one end portion at the contact portion of the peripheral edges is not in line with another end portion of the contact portion of the peripheral edges. The contact portion of the peripheral edges forms a load transfer path. In an embodiment, the contact portion of the peripheral edges is forward!)' inclined. In another embodiment, the contact ■ portion of the peripheral edges is rearwardly inclined. In yet another embodiment, the contact portion of the peripheral edges is having step shape. Moreover, the contact portion of the peripheral edges can be adapted to take any known regular or irregular shape, wherein the peripheral edges form a long load transfer path, which is greater than length of individual sub-side railing the sub-railing at that particular portion.
[00026] In an embodiment, a floorboard is disposed at floorboard portion, which is a step-through space. The floorboard is abuttingly supported by the left side railing and the right side railing. In an embodiment, the floorboard is disposed therebetween the left side railing and the right side railing. In an embodiment, the sub-railings disposed in proximity to the floorboard, which is a load-bearing member, are provide with peripheral edges, wherein one end of the

contact portion of the peripheral edges is not in line with another peripheral edge. In an embodiment, the floorboard has a central member and a pair of stiffeners. One stiffener is disposed adjacently of the right side railing and another stiffener is disposed adjacently of the left side railing.
[00027] In an embodiment, the side railings are provided with a C-shaped cross section. Further, an upper portion of the C-shaped cross-section is substantially outward with respect to a lower portion of the C-shaped cross-section of the side railing. Therefore, the C-shaped cross section makes an acute angle with respect to a vertical line. This provides affective banking angle of the vehicle thereby improving drivability of the vehicle and also provides aesthetic appeal.
[00028] In another embodiment, the side railings are provided with a D-shaped cross section. In an embodiment, the D-shaped cross section is formed by a C-shaped cross section and a stiffener, wherein the stiffener is connecting the upper portion and the lower portion of the C-shaped cross section of the side railing resulting in D-shaped cross section. In a preferred embodiment, the stiffeners are integrally formed with the railings. Further, the stiffener of the D-shaped cross section is abutted with an outer surface of the stiffener at the floorboard portion. The D-shaped cross-section provides improved load bearing capacity by providing additional support. Thereby, the pair of railings improves the load bearing ability of the monocoque structure.
[00029] The aforesaid and other advantages of the present subject matter would be described in detail in conjunction with the figures in the following description.
[00030] Fig. 1 illustrates an exemplary step-through type vehicle with a monocoque structure, in accordance with an embodiment of the present subject matter. The vehicle 100 has a monocoque structure 200 that acts as structural member and load bearing member of the vehicle 100. A handlebar assembly 105

is rotatably connected to a front wheel 110 through the monocoque structure 200 at a front portion F. The monocoque structure extends from a front portion F towards a rear portion R, which is along the longitudinal direction F-R of the vehicle 100. One or more front fork(s) 115 connect the front wheel 110 to the handlebar assembly 105. An engine assembly 120 is swingably" connected to the monocoque structure 200. Further, the engine assembly 120 is functionally connected to a rear wheel 125 through a transmission assembly (not shown). The transmission' assembly includes an automatic transmission, or a variable transmission system, or manual transmission system. The rear wheel 125 is rotatably connected to the transmission system and one or more rear suspension(s) 130 provided to damp forces acting on the rear wheel 125 from reaching monocoque structure 200. In another embodiment (not shown), a swing arm supports the rear wheel and the swing arm is swingably connected to the monocoque structure. A seat assembly 135 is positioned above engine assembly 120 and the seat assembly 135 in an open condition provides access to a utility box (not shown) disposed below the seat assembly 135. A pillion handle 140 is provided on the rear portion R of the vehicle 100.
[00031] A front fender 145 is provided at the front portion for covering at least a portion of the front wheel 110. A rear fender 150 is covering at least a portion of the rear wheel 125. Further, the vehicle 100 comprises of plurality of electrical/electronic components including a headlight 155 that is disposed in proximity to the handle bar assembly 105, a tail lamp 160 that is disposed rearwardly of the seat assembly 135, a battery (not shown), a transistor controlled ignition (TCI) unit (not shown), an alternator (not shown), and a starter motor (not shown). A front panel 165 acts as a windshield for deflecting air. In an embodiment, an electric motor (not shown) is hub mounted to the rear wheel 125. The engine assembly 120 and the hub motor act as power unit for the vehicle 100.

[00032] Fig. 2 (a) illustrates a left side view of a monocoque structure 200 for a step-through type vehicle, in accordance with an embodiment of the present subject matter. The monocoque structure 200 comprises a right side railing 205A and a left side railing 205B, together referred to as pair of side railings 205A, 205B. The right side railing 205A and the left side railing 205B are disposed at extreme ends in a vehicle width direction RH-LH. In the present embodiment, the pair of railings 205A, 205B extend from a below a handle bar assembly 105, extending downwards towards a floorboard portion FP and then inclinedly-rearward from the floorboard portion FP towards a tail lamp 160. The pair of side railings 205A, 205B is made of sheet metal. Further, the monocoque structure 200 includes a plurality of bridge members 210A, 210B, 215, and 220 connecting the left side railing 205A and the right side railing 205B, and disposed therebetween. The bridge members 210A, 210B, 215, and 220 are secured to the pair of side railing 205A, 205B.Further, the plurality of bridges 210A, 210B, 215, and 220 enable mounting of various parts, and provide structural strength at high load bearing and stress taking iocation(s) of the monocoque structure 200. A leg shield 235 is disposed in an anterior portion of the floorboard portion FP and said leg shield is connecting the pair of railings 205A, 205B.
[00033] In addition, the monocoque structure 200 includes a housing panel 225 positioned rearwardly of the floorboard portion FP, and supported by at least a portion of the right side railing 205A and the left side railing 205B. In the present embodiment, the housing panel 225 having a hollow structure includes a first opening (not shown) in the top portion that provides access to utility box (not shown). The bottom portion of the housing panel 225 is secured to an upper portion of the pair of side railings 205A, 205B. In an embodiment, the housing panel 225 is made of sheet metal and is welded to the pair railings 205A, 205B.

Further, the housing panel 225 encloses various vehicle parts, including a fuel tank (not shown), air filter assembly (not shown).
[00034] Furthermore, the right side railing 205A includes two or more right side sub-railings (not shown) and the left side railing 205B includes two or more left side sub-railings 205BA, 205BB, and 205BC. In a preferred embodiment, the left side sub-railings 205BA, 205BB, 205BC are welded together resulting in the left side railing 205B. A first left side sub-railing 205BA extends from below the handle bar assembly 105 towards the floorboard portion FP of the monocoque structure 200. A second left side sub-railing 205BB extends substantially in the longitudinal direction of the vehicle 100 and is disposed at the floorboard portion FP. A third left side sub-railing 205BC extends from floorboard portion FP towards the tail lamp 160 inclinedly. Similarly, the right side railing (not shown) is disposed on the right hand RH side.
[00035] The monocoque structure 200 includes a floorboard 230 that is disposed at the floorboard portion FP. The floorboard 230 is made of a rigid material. For example, the rigid material includes a sheet metal or plastic. Moreover, the floorboard 230 has a central portion that is substantially flat, thereby providing ease of carrying of loads. In a preferred embodiment, a railing bridge member 215 of the plurality of bridge members 210A, 210B, 215, and 220 is disposed below the floorboard 230 for providing support to the floorboard 230.
[00036] Furthermore, the right side railing 205A and the left side railing 205B are connected by a first front bridge member 210A and a second front bridge member 210B in a front portion F of the monocoque structure 200. Further, one or more rear bridge member(s) 220 are disposed in a rear portion R of the monocoque structure that connect the right side railing 205A and the left side railing 205B in the rear portion R.

[00037] Fig. 2 (b) illustrates an enlarged view of left side railing, in accordance with an embodiment depicted in Fig. 2 (a). The first left side sub-railing 205BA is secured to the second left side sub-railings 205BB, wherein a first trailing edge TE1 of the first left side sub-railing(s) 205BA that is facing a second leading edge LE2 of the second left side sub-railing 205BB. In the present embodiment, the first trailing edge TE1, which is the peripheral edge, is substantially inclined rearward. The second leading edge LE2, which is the peripheral edge, is substantially inclined forward. The railing 205B includes two or more sub-railings 205BA, 205BB, 205BC disposed adjoiningiy with peripheral edges TE1, LE2 of the sub-railings 205BA, 205BB having a contact portion CR One end portion EP1 of the contact portion CP is not in line with other end portion EP2 of the contact portion CP. A contact portion of the first trailing edge TE1 of the first left side sub-railing 205BA and the second leading edge LE2 of the second left side sub-railing 205BB is at an inclined angle. Furthermore, one end portion at the contact portion CP of the peripheral edges TE1, LE2 is not in line with other end portion of the contact portion/area of the peripheral edges TE1, LE2. In the present embodiment, the top portion, which is one end portion, is substantially forward when with reference to the bottom portion, which is other end portion, of the contact portion.
[00038] The contact portion between the first trailing edge TE1 of the first left side sub-railing 205BA and the second leading edge LE2 of the second left side sub-railing 205BB acts as load transfer path. In a preferred embodiment, the peripheral edges LE2, TE1 of the sub-railings are disposed in proximity to the load bearing members, for example the floorboard 230 thereby providing structural strength without affecting the aesthetics. Moreover, the contact area of the peripheral edges LE2, TE1 of the sub-railings 205BA, 205BB dampens effects of stress concentrations.

[00039] In one embodiment, a reinforcing plate is sandwiched between the peripheral edges TE1, LE2, wherein the reinforcing plate extends along the contact portion CP. The reinforcing plate provides structural strength and rigidity at the contact portion and the reinforcing plate provides simple reinforcement to the monocoque structure 200.
[00040] Fig. 3 illustrates an enlarged view of left side railing, in accordance
with another embodiment of the present subject matter. The left side railing 305B
includes a first side sub-railing 305BA and a second side sub-railing 305BB. A
contact portion between a first trailing edge TE1 of the first left side sub-railing
305BA and a second leading edge LE2 of the second left side sub-railing 305BB
acts as load transfer path. Furthermore, one end portion of the contact area of the
peripheral edges TE1, LE2 is not in line with another end portion of the contact
area of the peripheral edges "TE1, LE2. In the present embodiment, the one end
portion of. the peripheral edges TE1, LE2, which is the top portion is at a
horizontal offset with respect to rest of the contact area of the peripheral edges
TE1, LE2 " *
[00041] Fig. 4 (a) depicts a top perspective view of a portion of the monocoque structure, in accordance with the embodiment depicted in Fig. 2. A floorboard 230 is disposed at floorboard portion FP (shown in Fig. 2), which is a step-through space. In the present embodiment, the floorboard 230 is abuttingly supported by the left side railing 205A, and the right side railing 205B, therebetween. The floorboard 230 is made of a rigid material, for example sheet metal of any known metal, and is secured to the pair of railings 205A, 205B by welding or fastening. The floorboard 230 has a central portion that is substantially flat with respect to a horizontal plane. The floorboard 230 further comprises a pair of stiffener plates 240A, 240B that extend outward from the central portion, which is the floorboard 230. In a preferred embodiment, the pair of stiffener plates 240A,

240B extends downwardly outward from the central portion and disposed at lateral ends of the central portion. The one or more stiffener plates 240A, 240B connect an upper portion UP of the side railing with a lower portion LP of the side railing. In a preferred embodiment, the central portion and the stiffener members are integrally formed. Further, the right side railing 205A is disposed adjacently of one stiffener, which is disposed on the right hand RH side, and the left side railing 205B is disposed adjacently of another stiffener, which is disposed in the left hand LH side. The stiffener plates 240A, 240B are abutted to the pair of railings 205A, 205B having C-shaped cross-section thereby providing strength to the monocoque structure at the floorboard portion FP. Furthermore, the stiffener plates 240A, 240B are providing strength in a perpendicular direction to the load direction, which is acting from the upward on the floorboard 230.
[00042] Fig. 4 (b) depicts a cross-sectional view of the monocoque structure depicted in Fig. 4 (a), taken along the axis X-X'. Fig. 4 (c) depicts the cross sectional view of the side railing, in accordance with the embodiment depicted in Fig. 4 (a). The left side railing 205A and the right side railing are provided with a ■ C-shaped cross-section. Further, the right side railing 205A and the left side railing 205B includes an outer face OF with an upper portion UP and a lower portion LP, said upper portion UP extends substantially outward in a vehicle width direction RH-LH with respect to the lower portion LP of the outer face OF. The thickness of the side railing 205A is chosen in accordance with the load-carrying requirement at location. An upper portion of the C-shaped cross-section is substantially outward with respect to a lower portion of the outer surface of.the C-shaped "cross-section of the right side railing 205A and the left side railing 205B. A web area of the pair of railings 205A, 205B supports the stiffener plates 240A, 240B thereby supporting the floorboard of the monocoque structure 200. Therefore, the outer face OF of the C-shaped cross section makes

an angle alpha a with an imaginary vertical line V. The angle alpha a is chosen to enable banking of the vehicle 100. This provides effective banking angle of the vehicle thereby improving drivability of the vehicle 100 and also provides aesthetic appeal.
[00043] Fig. 5 depicts a cross-sectional view of a side railing member, in accordance with yet another embodiment of the present subject matter. The cross section of the right side railing 405A has a D-shaped cross-section. The side railing 405A includes one or more stiffener plates 435A connecting an upper portion UP of the side railing 405A with a lower portion LP of the side railing 405A. In addition, an upper portion of the side railing 405A is substantially outward with respect to a lower portion of side railings 405A. Further, the D-shaped cross-section includes a stiffener 435A, which is integrally formed with the side railings 405A, connecting the upper portion and the lower portion of the right side railing 405A. The D-shaped cross-section improved load-bearing capacity by providing additional support. Further, the pair of railings 405A improves the load bearing ability of the monocoque structure. In a preferred embodiment, the stiffener plates are integrated with the C-shaped cross-section of the railings 405A thereby resulting in D-shaped cross-section. The side railings 205A includes the C-shaped cross section with an open face OPF of, the C-shaped cross-section facing inward with respect to said vehicle 100. The top portion and the bottom portion of the C-shaped cross-section, which includes the web area, along with the stiffener plates 435A support the floorboard 230 of the monocoque structure. Moreover, the stiffener 435A plates are inwardly disposed thereby improving structural strength without affecting aesthetics of the monocoque structure. The side railing 405A along with the stiffener plates 435A forms a closed cross-section including the D-shaped cross section providing improved structural strength and rigidity.

[00044] Fig. 6 depicts a cross-sectional view of the floorboard portion of the monocoque structure, in accordance with an additional embodiment of the present subject matter. The pair of railings 505A, 505B is disposed at extreme lateral ends of the vehicle 100 and a floorboard 230 is supported by the pair of railings 505A, 505B, and therebetween. A railing bridge member 515 is disposed below the floorboard 230 and secured to the pair of railings 505A, 505B. The railing bridge 515 is provided with plurality of ducts 535, which are disposed substantially along the longitudinal direction of the vehicle that enable routing of electrical and mechanical cables. Further, in the present embodiment, additional support portion 505AAS, 505BAS provided on each of the pair of railings 505A, 505B that support the railing bridge 515. The support portion abuttingly extends downwardly inward of railing bridge member 515. The support portion provides structural strength by supporting the weight of the bridge member 515, which in turn supports the floorboard 230.
[00045] The bridge member 515 is having a closed cross-section, and the side railings 505A, 505B includes an additional support portion 505AAS, 505BAS extending inward supporting at least a portion of the bridge member 515. [00046] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.

We claim:
1. A monocoque structure (200) for a two-wheeled vehicle (100) comprising:
a right side railing (205A, 405A, 505A), and a left side railing (205B, 305B, 505B) extending rearward from a substantially front portion of the vehicle (100) and inclinedly rearward towards a substantial rear portion of the vehicle (100), and said right side railing (205A, 405A, 505A) and said left side railing (205B, 305B, 505B) are disposed substantially at a vehicle width end(s) (RH-LH); and
one or more bridge member(s) (210A, 210B, 215, 220, 515) connecting said right side railing (205A, 405A, 505A) and said left side railing (205B, 305B, 505B), and being disposed therebetween,
wherein
at least a portion of said railings (205A, 405A, 505A, 205B, 305B, 505B) includes an outer face (OF) with an upper portion (UP) and a lower portion (LP), said upper portion (UP) extends substantially outward in a vehicle width direction (RH-LH) with respect to said lower portion (LP) of said outer face (OF).
2. The monocoque structure (200) of claim 1, wherein said side railing (205B) includes two or more sub-railings (205BA, 205BB, 205BC) disposed adjoiningly with peripheral edges (TE1, LE2) of said sub-railings (205BA, 205BB) having a contact portion (CP), wherein one end portion (EP1) of said contact portion (CP) is not in line with other end portion (EP2) of said contact portion (CP).
3. The monocoque structure '(200) of claim 1, wherein said railing said side railing (205B, 305B) includes two or more sub-railings (205BA, 205BB, 305BA, 305BB) disposed adjoiningly with peripheral edges (TE1, LE2) of said sub-railings (205BA, 205BB) having a contact portion (CP), wherein said contact portion (CP) is having a non-linear profile thereby providing improved contact.
4. The monocoque structure (200) of claim 1, wherein said side railing (205A, 205B, 405A) includes one or more stiffener plate(s) (240A, 240B, 435A)

connecting an upper portion (UP) of said side railing (405A) with a lower portion (LP) of said side railing (405A)
5. The monocoque structure (200) of claim 1, said side railing(s) (205A) includes a C-shaped cross section with an open face (OPF) of said C-shaped cross-section facing inward with respect to said vehicle (100).
6. The monocoque structure (200) of claim 1 or 4, wherein said side railing (405A) along with said stiffener plate(s) (435A) forms a closed cross-section including a D-shaped cross section.
7. The monocoque structure (200) of claim 1, wherein said bridge member (515) is having a closed cross-section, and side railing(s) (505A, 505B) includes an additional support portion (505AAS, 505BAS) extending inward supporting at least a portion of said bridge member (515).
8. The monocoque structure (200) of claim 1, wherein said bridge member (515) includes plurality of ducts (535) disposed substantially along a longitudinal direction (RH-LH) of the vehicle (100) for routing of electrical or mechanical cables therethrough.
9. The monocoque structure (200) of claim 1, wherein said monocoque structure (200) includes a flat floorboard (230) supported by at least one of said right side railing (205A), said left side railing (205B), said one or more bridge member(s) (515), and one or more stiffener plate(s).
10. The monocoque structure (200) of claim 1, wherein an outer face (OF) of said side railing (205A) is disposed at an angle alpha (a) with respect to an imaginary vertical line (V), wherein said angle alpha (a) is an acute angle.