Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5

i Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Equation Chapter 1 Section 1 Final Degree Project Aerospace Engineering Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Author: Ignacio Rosales Silván Tutor: Laura García Ruesgas Departamento de Ingeniería Gráfica Escuela Técnica Superior de Ingeniería Universidad de Sevilla Sevilla, 2020 ii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 iii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Final Degree Project Aerospace Engineering Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Author: Ignacio Rosales Silván Tutor: Laura García Ruesgas Collaborating professor Departamento de Ingeniería Gráfica Escuela Técnica Superior de Ingeniería Universidad de Sevilla Sevilla, 2020 iv Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 v Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Final Degree Project: Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Author: Ignacio Rosales Silván Tutor: Laura García Ruesgas The tribunal appointed to judge the above Project, composed of the following members: President: Vowels: Secretary: Agree on granting the calification of: Sevilla, 2020 Court Clerk vi Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 vii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 To my family To my teachers To my colleagues viii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 ix Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Acknowledgements Firstly, I would like to thank my mother, my brother, my aunt and the rest of my family for the constant support they have given me throughout the degree, giving me their advice and collaborating as much as possible in anything that could help my learning. I am also grateful for the, sometimes excessive, constant insistence and pressure I was subjected to regarding my studies, as their aim was no other than their desire for me to reach my goals as soon as possible. My most sincere thanks from the bottom of my heart because without them, none of this would have been possible. I would also like to thank my colleagues, with whom I have spent long hours of study, good and bad times regarding the university, but we have always supported and helped each other move forward. I would especially like to thank one of them regarding this project, Elena, who has given me her constant support by giving me her unselfish opinion about the progress I was making on the project, as well as pointing it out when she considered that I could design something more realistically, what allowed me make a much better design of the helicopter. At last but not least, thanks to my teachers for all the teachings given during these years, especially Laura García Ruesgas, who attended my request for a final project, showed me her interest on it, and has supported me with any problem that has arisen and any decision taken. Ignacio Rosales Silván Escuela Técnica Superior de Ingeniería Sevilla, 2020 xvi Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Index of illustrations Illustration 1: Mil V-12 1 Illustration 2: Mi-12 scale model with tandem-rotor configuration 5 Illustration 3: Mi-12 scale model 5 Illustration 4: Table of world records achieved 8 Illustration 5: Scale model of the Mi-12M variant 9 Illustration 6: Secondary blueprint 11 Illustration 7: Main blueprint 12 Illustration 8: Fuselage pointed out in the blueprints 15 Illustration 9: Fuselage profile 16 Illustration 10: Fuselage surface 17 Illustration 11: Fuselage surface with windows shape 17 Illustration 12: Fuselage with thickness 18 Illustration 13: Mi-12 lateral view 18 Illustration 14: Complete external fuselage design 19 Illustration 15: Real backside of the inside of the fuselage 20 Illustration 16: Real front side of the inside of the fuselage 20 Illustration 17: Inside of the modelled fuselage 21 Illustration 18: Floor of the fuselage 21 Illustration 19: Fuselage floor structure 22 Illustration 20: Fuselage complete formers 23 Illustration 21: Fuselage floor structure details 23 Illustration 22: Real vertical structures 24 Illustration 23: Fuselage vertical structures 24 Illustration 24: Door structures and all formers 25 Illustration 25: Fuselage longerons and longitudinal ducts 25 Illustration 26: Ceiling structure 26 Illustration 27: Real fuselage floor 26 Illustration 28: Fuselage floor details 27 Illustration 29: User pattern example 27 Illustration 30: Fuselage with stringers 28 Illustration 31: Fuselage Windows 29 xvii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 32: Longeron details: 29 Illustration 33: Fuselage to cockpit Wall 30 Illustration 34: Fuselage final design 30 Illustration 35: Nose pointed out in the blueprints 32 Illustration 36: Nose of the Mi-12 32 Illustration 37: Nose sketches 33 Illustration 38: Nose first design 34 Illustration 39: Nose final design 34 Illustration 40: nose upper structure 35 Illustration 41: Real nose external detailed image 35 Illustration 42: Modelled nose with Windows 36 Illustration 43: Real nose low side structure 37 Illustration 44: Nose low side structure 37 Illustration 45: Close real view of the nose 38 Illustration 46: Left side of the nose 39 Illustration 47: Right side of the nose 39 Illustration 48: Antennas and hatch 40 Illustration 49: Outside view of the nose design without landing gear 40 Illustration 50: Final outside nose geometry 41 Illustration 51: Cockpit real lower floor 42 Illustration 52: Cockpit modelled lower floor 42 Illustration 53: Cockpit real upper floor 43 Illustration 54: Cockpit modelled upper floor 43 Illustration 55: Dockpit real corridor 44 Illustration 56: Dockpit modelled corridor 44 Illustration 57: Mil Mi-12 poster 45 Illustration 58: Main control panel 46 Illustration 59: Gas lever and pedals 46 Illustration 60: Cockpit with gas levers and pedals 46 Illustration 61: Front view of pilot modelled seat 47 Illustration 62: Back view of pilot modelled seat 47 Illustration 63: Cockpit with pilot and copilot seats 47 Illustration 64: Copilot area with modelled handbrake 48 Illustration 65: Secondary control panels 49 Illustration 66: Other seats modelling 49 Illustration 67: Ceiling control panel 50 Illustration 68: Back side of the stairs and wall cockpit-corridor 51 Illustration 69: Corridor benches 51 xviii Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 70: Corridor to fuselage wall 52 Illustration 71: Stairs modelled 52 Illustration 72: Binocular system 53 Illustration 73: Upper floor main control panel 53 Illustration 74: Shelf rack and ladder 54 Illustration 75: Tail pointed out in blueprints 56 Illustration 76: Mi-12 real tail 57 Illustration 77: Mi-12 with open tail gate 57 Illustration 78: Tail sketches 58 Illustration 79: Tail multi-sections surface 58 Illustration 80: Closure surface sketches 59 Illustration 81: Closure surface 59 Illustration 82: Modelled tail external geometry 60 Illustration 83: Real inside view of the tail 61 Illustration 84: Modelled inside of the tail 61 Illustration 85: Tail floor 62 Illustration 86: Side gates formers 63 Illustration 87: Oblique former 63 Illustration 88: Tail with all formers 64 Illustration 89. Ceiling tail structure 65 Illustration 90: Side gates longerons 65 Illustration 91: Tail with all longerons 66 Illustration 92: Tail to fuselage former 66 Illustration 93: Sliding platform 67 Illustration 94: Stabilizers surfaces 68 Illustration 95: Tail fully modelled 69 Illustration 96: Mi-12 photograph 71 Illustration 97: Outer elements pointed out in the blueprints 71 Illustration 98: Wing box surface 72 Illustration 99: Wing box 72 Illustration 100: Engine sketches and surface (1) 73 Illustration 101: Engine sketches and surface (2) 73 Illustration 102: Engine solid 74 Illustration 103: Wing profile blueprint 74 Illustration 104: NACA4418 profile 75 Illustration 105: Wing surface 75 Illustration 106: Solid wing 76 Illustration 107: Detailed engine 76 xix Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 108: Rotor 77 Illustration 109:NACA4415 profile 77 Illustration 110: NACA4415 section 78 Illustration 111: Rotor (2) 78 Illustration 112: Landing gear and rods 79 Illustration 113: Fuel tank 80 Illustration 114: Outer systems and structures 80 Illustration 115: Front view of the aircraft 82 Illustration 116: Back view of the aircraft 82 Illustration 117: Plant of the aircraft 83 Illustration 118: Rendered image 1 83 Illustration 119: Rendered image 2 84 Illustration 120. Rendered image 3 84 xx Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 1 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 1. Introduction The present work, as its title indicates, will focus on the analysis and design of the helicopter Mil v-12, however, the decision of which aircraft should be designed was not that easy to take. The first decision taken was doing a final project based on the use of CATIA, as the graphic design and 3D modelling has always been something really attractive to the author of this project. The important decision to take was which aircraft should be modelled. At the beginning all the options envisaged were planes designed and used in the Second World War, however, after some research it became apparent that many of them had already been designed, which would mean that any similar design would not be very innovative, as well as the modelling of any commercial aircraft. For that reason, it was decided to take some other kind of aircrafts into account, helicopters and spaceships. After some research and excluding other options, the aircraft which suited better all the requirements was the helicopter Mil V-12 or Mil Mi-12. Illustration 1: Mil V-12 2 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Once decided, the project was presented to the professor Laura García Ruesgas, who was immediately interested on the decision of modelling such helicopter, the reasons are evident, it is not a common design project, not only because it is a helicopter, but because of its structure. As it is a huge helicopter, it is anything but simple both internally and externally, moreover, its configuration is not any usual, as the rotors are located over two wings, unlike most of them. Finally, there are some other Mil, as it is the name of a set of helicopters made by a Russian company, it was decided that the helicopter Mil V-12 was the best choice not only because of its structure, but also the world records it achieved, as will be mentioned further on. Therefore, there are no 3D models of the helicopter Mil V-12 available on the net, so the requirement of making a design of it became obvious, as it could be useful in case somebody wanted to get some information about the structure of such helicopter, check information about its size accurately or even creating a 3D model by printing it with manufacturing purposes. For that reason, the final step to take is to decide which program should be used to model this aircraft. In this case the answer is evident, not only because there has been a subject delivered which included all the basics of CATIA, but because it is clearly one of the most powerful program regarding to 3D modelling, if not the most powerful one. 3 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 2. Mil V-12 helicopter 2.1. Objectives Design studies for a giant helicopter were started at the Mil OKB in 1959, receiving official sanction in 1961 by the GKAT (Gosudarstvenny Komitet po Aviatsionnoy Tekhnike – State committee on Aircraft Technology) instructing Mil to develop a helicopter capable of lifting 20 to 25 tons. In order to accomplish these objectives, the Mi-12 project was started in 1965 with the aim of producing a vertical take-off aircraft capable of carrying soldiers, equipment and supplies. Actually, as it can be seen, this aircraft was built during the Cold War, and that is why the main elements that would have been moved on by the Mil Mi-12 were heavy nuclear missiles and other loads compatible with those of the four-engine Antonov An-22. It is worth to mention that the bureau chose a side-by-side rotor formula, as will be explained later, in order to use the engine-transmission-rotor assembly of the helicopters of the Mi-6 and Mi-10 series with minimal modifications, what would highly reduce the costs and the time spent. Even though this is the main reason behind the design of the helicopter Mi-12, there are two more of them which had an important weight on the decisions taken. The first one is that at this period, Soviet Union and the US were racing with each other in a technological way. For this reason the government was looking to have the most powerful vehicle, further than because of its use, to show their enemies that they had better aircrafts to assist the military in case of a conflict. The second reason has nothing to do with the military use, as the Mi-12 was probably intended for service with Aeroflot too, especially for deployment in areas of Siberia which are rich on resources but which have very poor communication. 2.2. Design and characteristics In this sections the main characteristics of both the inside and the outside of the Mi-12 will be mentioned, as well as some of the facts that took place during the design. At the beginning of the design process, control of the Mi-12 presented several problems to the designers and engineers due to the sheer size as well as rotor layout. Therefore, the Mi-12 was initially thought to have a tandem-rotor layout, however, Mil received early permission to concentrate instead on a twin side-by-side rotor configuration, which the design bureau claimed as having better reliability, fatigue life and stability. 5 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The wings, unlike in most of the planes, have an inverse taper from the root to the wingtips. The following photograph shows a scale model with the first configuration contemplated for this aircraft. However, as it has been explained, such project was never carried out. Illustration 2: Mi-12 scale model with tandem-rotor configuration For this reason, in the final configuration the two engines are located side-by-side with twin intakes, and drive five-blade metal rotors. The left rotor rotates anti-clockwise and the right unit clockwise. Both units are connected by transverse shafting to ensure synchronization and the continued rotation of both units in the event of engine failure at either wingtip. The lower part of each cowling can be dropped to form a working platform for mechanics and fuel is housed in two cylindrical tanks mounted externally on the lower fuselage sides. On the ground, the helicopter was supported by fixed tricycle landing gear with two wheels each unit, which are supported by a plethora of struts bracing the wings and running from the lower fuselage, wings and engines. The last thing to mention about the outside components of the aircraft is the large end-plate fin tail unit that can be found mounted at the rear of the fuselage, with moving vertical and horizontal surfaces. Illustration 3: Mi-12 scale model 12 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 7: Main blueprint Both blueprints have been used in the design process, especially the second one, which, as can be seen, includes the approximate shape of some profiles along the aircraft, as well as a section of the wing. It should be mentioned that, although the scale is indicated in the second blueprint, it did not correspond accurately with all the measures, probably because the dimensions of the blueprint might have been modified when being uploaded to the net. 13 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 As it is evident, these blueprints present a level of detail truly decent of the main structure, but not enough regarding the detail of the structure. For that reason it could be anticipated that there would me some approximations during the modelling process. Also, as we can see, in the pictures above we can barely find any detail related to the inside of the structure, which is planned to be designed too. For this reason, it was necessary to get other documents which provided such information, like photographs or videos, some of which will be shown in future sections of this project. The next step to take was to decide which would be the modelling process. At the beginning, the design was thought to be divided into seven different parts, which would be fuselage, nose, tail, stabilizers, wings, engines and other details, however, at the end the design was divided into four sections, which have been fuselage, nose, tail and stabilizers in the third division, and the last one which contains the wings, engines and any other detail of the structure, such as fuel tanks or bars, all designed in that order. With all the different parts, firstly it was modelled the external structure, followed by the internal one. The CATIA modules employed in this project are three, part design, generative shape design and assembly design, each of which will be mentioned when used in the following sections. From now on, in order to differentiate properly the terms related to CATIA, all of them will be written in cursive. It is necessary to be mentioned that some of the systems of the helicopter will not be modelled in this project, for this reason, no wire will be modelled, as well as will happen with any other subsystem located under the floor of the helicopter, the reasons are simple, the first one that most of them are not rigid parts, so most of them do not have a single configuration, the second one is that some other are moving parts, so the place where they are located can change from some photographs to others, the last one is that the subsystems located under the floor are not able to be designed, as there is no information about their layout. 14 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 15 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4. Mil Mi-12 3D modelling 4.1. Fuselage (Body) The first section to be modelled has been the fuselage, as it is the central part on which all the other divisions will be assembled. For that reason, all the measures and the shape related to the fuselage had to be defined since the beginning. The section that has been called fuselage, from now on in this project, corresponds to the one included into the blue rectangle in the image below. Illustration 8: Fuselage pointed out in the blueprints 4.1.1. External modelling The starting point in order to design the fuselage is the profile “C” included in the blueprints. As can be seen in the blueprints, the shape of the fuselage is anything but constant in the nose and the tail, however, the height and the width of the fuselage remains constant from the beginning to its last point. This, of course, is a starting hypothesis, but having a look at the blueprints and photographs provided, it can be considered as a quite accurate assumption. Once decided that the fuselage profile would be constant along the body, the next task has been to design as accurately as possible the shape shown in the previous image as section “C”. In order to do so, the measures of eight points have been taken, the highest and lowest points, the points which define the maximum width, and four intermediate points, one between each of the four mentioned. With these points, the first attempt was so make a spline using them, however, the result was not the desired, as the curve became wider in points we did 16 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 not want it to, as well as happened with the lowest and highest points, and in case that it was tried to force a tangent situation in some of the points, the spline caused an error. For that reason, a different approach to the problem was taken, instead of forcing a spline to include the points, it was decided to use the command connect, which takes two curves and connect them tangentially. In order to set the extremes, in each of those points it was defined a straight line with the desired tangent direction. Once this was done, the command previously mentioned was used to connect the lines. By default, the line generated with this command has a particular curvature, however, the tension related to each endpoint of the line can be modified, what was done in order to obtain the required shape, as it is shown in the image below. At last, it is worth to mention that, effectively, we have included four straight lines in the design of this curvature, however, as the length of such lines can be set, if has been changed to a length of 1 mm, which can be considered negligible compared to the total width or height, exceeding both the 5 meters. The resulting shape is the showed in the next image. Illustration 9: Fuselage profile 17 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 With the profile shape definitely decided, to model the main structure of the fuselage it was applied the module generative shape design, more specifically, the command extrude along the “Y” axis, resulting into the image below. Illustration 10: Fuselage surface 4.1.1.1. Windows Before applying a thickness to the fuselage surface, it was necessary to make a difference between the places in which there would be a sheet of metal, and the areas where the windows would be positioned, as these two subdivisions had been intended to be designed using different materials, in order to differentiate them properly. With that aim, the procedure taken was the following. First each of the windows shape was designed in the plane “YZ”, taking the measures and positions from the blueprints already mentioned. Secondly, each one of this sketches has been projected on both sides of the surface with the command project. With these projections made, it was necessary to differentiate the inside and outside area of such projections, what was done with the command extract. Finally, the surface was divided into the desired ones by using the command split between the main surface of the fuselage and each of the windows, always choosing to keep both parts. The consequent surface is the one shown. Illustration 11: Fuselage surface with windows shape 18 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Once this structure had been defined, it was time to add a thickness to both the sheet of metal conforming the fuselage and the windows made of glass, it has been done with the command thick surface, leading to the following structure. Illustration 12: Fuselage with thickness 4.1.1.2. Doors The last thing to design regarding the outside of the fuselage are the doors, as we can see in the next image, as well as can be done in the blueprints shown, along the fuselage there are a total of four doors, two on each side, all of them are sliding doors, and guides can be easily observed. Illustration 13: Mi-12 lateral view In order to model a door, the first step taken has been to make a hole of 0.1 mm along the contour of the door by using the command pocket, its use is purely visual, as there will not be animations included in this project, but it can be useful to differentiate the position of the doors, as well as possibility the future application of animations. Afterwards, there were designed the guides of the sliding door. In order to do so, as well as it was done with the windows, the projection of the contour that the guide should follow was modelled in a sketch in the “YZ” axis, by using the command project along the “X” axis, the curve that the guide followed would be set. 19 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 At that point, it was only necessary to create a sketch in a plane perpendicular to that curve, with the desired shape of the guide, in order to use the command rib on that sketch over the previously created curve. To finish the details of the guides, two more commands were used to improve its shape, edge fillet, to add curvature, and shaft, to close some plane surfaces. Once one door had been designed, two of the other three were modelled too by using the commands rectangular pattern and mirror on the operations previously mentioned, the last one was created by using the same method of the same door, the reason is that it cannot be done a mirror of a pattern or vice versa. The final result is contemplated in the following image. Illustration 14: Complete external fuselage design 20 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.1.2. Internal modelling With the external shape completely designed, the next step to take is the design of all the elements which compose the inside of it. The only way to obtain information about the inside of the aircraft has been via photography, as there are no blueprints which show where the different structures are located or their sizes. Therefore, all the designs made in the following sections have all been estimated as accurately as possible, but without specific measures. First of all, before explaining the design process of each element, it is worth to show a couple of photographs of the inside of the fuselage, as well as two images of the inside of the fuselage fully modelled. Illustration 15: Real backside of the inside of the fuselage The first photograph shows the backside of the fuselage, while the second one illustrates the front side of it, showing a wall with a door, which would connect to the cockpit. As it was previously mentioned, all the wires that can be seen, most of which are attached to the top of the fuselage, will not be modelled. Instead, there has been designed a duct, which would hold them. On the third image it can be seen the mentioned fully modelled fuselage, which, in order to grant a better view, has been cut before making the photograph. Illustration 16: Real front side of the inside of the fuselage 21 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 17: Inside of the modelled fuselage The main objective of showing these illustrations is to have an idea about the location of the elements which are going to be designed in the following sections, therefore most of them will just be mentioned and make a reference to these images, in order to avoid the repeatability of providing a photograph of the real element for each section.The order followed in the sections below is the same order of design processes that have taken place. 4.1.2.1. Floor The floor has been truly easy to design, it has been modelled at the desired height by using the command pad, by setting the limit in up to next. As it was said in previous sections, the floor is not completely a solid, but it has been created as one in this project, in order to simplify the operations and make it visually more attractive. Illustration 18: Floor of the fuselage 28 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 One of the patterns, the shown in the picture above, defines the points where the stringers that cover the whole length will be placed. The other two patterns have been made in an analogue way, one of them for the stringers that only have doors on their way, and the other one for stringers which have to avoid both doors and windows. With this method, a task that could involve the use of hundreds of pads, is reduced to the application of a few pads and user patterns. The final result, seen on a half of the fuselage, is the following one. Illustration 30: Fuselage with stringers 4.1.2.11. Windows The windows design has been anything but trivial, as can be seen, there is a surface that connects the contour of the windows with the formers and longerons that surround each one of them. The point is that the surface defined by the longerons and formers is not a plane, in consequence, there has been the need to work with the generative shape design once again. With this module, it has been created a curved surface with the command fill. Over this surface, there has been projected a curve created in a sketch in the plane “YZ” by using the command project, the reason of creating such curve is simple, there is an intention to create a multi-section surface using the shape of the window and the outer profile, but as the window is defined by a circle, the outer shape should not have any corners. Once created the new curve, there is going to be used the command split on it, keeping only the outer surface. Afterwards, it will be created a multi-section surface with the two already mentioned profiles. Finally, there will be made two pads up to surface, in order to fill the desired area. At last, it can be seen that the formers surrounding each window have four holes at this same height, all these holes have been modelled with pockets. 29 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The final result of the windows can be contemplated on the picture below. Illustration 31: Fuselage Windows 4.1.2.12. Longeron details By paying attention, it can be observed that one of the longerons, and its symmetrical one, have several holes along them. In order to model these holes, as the distance between them is not equal, it has been decided to create a user pattern, leading to this result. Illustration 32: Longeron details: 4.1.2.13. Fuselage to cockpit wall The last thing to be modelled in the fuselage has been the wall that connected the main body with the cockpit, which was shown in the second photograph of the section 4.1.2. As can be seen, there are mainly four elements to design: the wall itself, with its stiffeners, the hole that would simulate the door, the stairs and the structure located on the middle of the wall, which also has some stiffeners. The wall, the structure and all the stiffeners have been created with pads, and pockets have been used to create the door hole. Some details of the structure have been designed with the use of drafts and pockets. Finally, to model the stairs there have been applied the commands rib and pad. 30 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The modelled wall can be contemplated in the next image. Illustration 33: Fuselage to cockpit Wall It is worth to mention that the wall has been designed after the nose, this is the reason why there has not been modelled the door in this part, because it has been created in the nose modelling. With all these structures created, the complete fuselage has been fully modelled both internally and externally, once again, it is shown an image of the final result, in order to observe all the elements created one by one together. Illustration 34: Fuselage final design 31 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 32 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2. Nose The next section modelled has been the nose of the aircraft, both externally and internally. At that point there is only one specific limitation, the last profile of the cockpit (the closer one to the fuselage) must coincide with the constant profile employed to generate the body in both shape and size, as the target is to assemble all the parts. The nose, from now on called cockpit when it is being talked about the internal side of it, corresponds to the section inside the orange rectangle seen below. Illustration 35: Nose pointed out in the blueprints 4.2.1. External modelling Before explaining the modelling, the following images illustrate the real and the modelled outside of the nose, the purpose of showing this is, as it was done with the inside of the fuselage, show a general overview, in order to know the position of the elements that will be designed further on, as well as the final result. Illustration 36: Nose of the Mi-12 33 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.1.1. General shape Therefore, the starting point to design the shape of the nose is to impose the profile of the fuselage at the end of its length. This time, however, the section of the nose is anything but constant along its length, so, in order to model it, there have been taken the total height and width of twelve sections by measuring the blueprints at its corresponding defined points. The problem was that, as it can be seen taking a look at the sections “A” and “B” in the image above, not only the size of the profiles do change along the “Y” axis, but also their curvature. To solve this problem, there has been made an approximation, there have been used the measurements and shapes taken from the three profiles (the both mentioned and the imposed one at the end), and the other eight have been extrapolated. In order to do so, it has been extremely useful to having employed the command connect, which has been already explained in previous sections. The point of its utility is that, once there have been set the required tensions from each extreme for every curve, in order to achieve the desired shape in the three shapes that are known, the intermediate sections can use a tension dependence between them, what has highly facilitated the task. The twelve sketches are shown in the following image. Illustration 37: Nose sketches With all the sketches defined, it was time to create the surface. In order to do that, it has been used once again the module generative shape design, but in this case, all of these profiles has been applied the command multisections surface. 34 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 As it can be foreseen, the initial shape was not a very accurate one, mainly because the measurements had been taken from the print of the blueprints, which did not have a good enough quality. Illustration 38: Nose first design Consequently, some of the profiles were redefined, moreover, there was taken the decision of using only seven sketches, as taking too many of them with wrong measures would only contribute in a negative way, in this case, it became obvious that it is better to use only a few accurate sections rather than many of them if some are not the exactly ones. Illustration 39: Nose final design 35 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.1.2. Upper structure In order to create the upper structure of the nose, it has been used the module generative shape design. More specifically, it has been modelled the shape of the hole in a horizontal plane and projected on the upper surface of the nose with the command project. Such projection has been applied a split and, with another created sketch to define the ceiling of the structure, the whole surface has been closed with a multi-section surface and a fill. Illustration 40: nose upper structure 4.2.1.3. Windows and thickness After having created the whole external shape of the nose, it is time now to create the windows and add a thickness to them and the sheets of metal. The windows have to be modelled before applying the thickness for the same reason mentioned when the fuselage was created. Illustration 41: Real nose external detailed image 36 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Following the same steps, some sketches, which define the shapes of the windows, have been projected on all the required positions, then, applying the commands split and thick surface, the windows have been created. There are two windows that do not follow the curvature of the nose, it is something a bit hard to realize, but it is possible to check it by watching the previous image in detail. Due to this reason, these windows have been modelled with the command fill, which allows the user to choose a passing point. There has been designed the furthest point to the original curvature in the middle of the window. Finally, there has been used the command thick surface of the module part design to add thickness to both the sheet of metal and the windows, each one with its corresponding material application. Additionally, the hole of the tip of the nose has already been closed. Illustration 42: Modelled nose with Windows It is worth to mention that some of the windows created belong to the doors, for this reason, when the doors design is explained, the modelling of the windows which are inside them will be omitted 37 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.1.4. Downside structure On the low part of the nose it can be found a semi ellipsoidal structure, which has been modelled, as it is evident, with a shaft. It has been applied white color, which corresponds with the real color, in order to be differentiated properly Illustration 43: Real nose low side structure Illustration 44: Nose low side structure 44 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Additionally, although it is in the lower floor, there is a corridor separated from the cockpit by a wall. However, if has been modelled as a part of the nose of the aircraft. Such corridor can be seen below. Illustration 55: Dockpit real corridor Illustration 56: Dockpit modelled corridor 45 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Finally, although everything has been modelled based on the photographs already given, in some occasions it has been helpful to check the following poster. Illustration 57: Mil Mi-12 poster From now on, it will be assumed that the position of every element designed is already known, as all of them appear in the images shown. As well as it happened in the fuselage with the wires, in this section the cloth that covers the ceiling of both floors will not be modelled. The design order will be: first the lower floor, secondly the corridor and at last the upper floor. Some of the elements modelling, like the chairs, which are equal in both floors, will not be modelled again in the second one to avoid redundancies. 4.2.2.1. Control Panel In this section it has been avoided the explanation of the floor has been crated, as the procedure has been the exactly same that the followed with the floor of the fuselage, which consisted on doing a pad with the limit option set in up to next. First of all, there have been created two platforms, over which the seats of the pilot and copilot will be located, there is not a section to define them because it has been simply modelled with pads and edge fillets. Regarding the control panel design, it can be observed that it has a certain inclination from the panel itself and its intersection with the fuselage. In order to recreate the shape as accurately as possible, plenty of commands have been used, mostly pads, pockets, multi-sections solids, slots and mirrors. 46 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Once the main structure has been built, there have been added several pads, which have been painted in a grey color with the only purpose to represent the indicators of the panel. Illustration 58: Main control panel 4.2.2.2. Gas lever and pedals Both pilot and copilot do have a gas lever and a pair of pedals in front of their seats. Both elements have a platform which has been created with a pad, and also both of them are composed by curved rods, for that reason, it has been necessary to create sketches with the curves that each profile should follow, and by defining their profiles, using the command rib over such curves. Finally, some of the edges have been applied an edge fillet. The gas lever and pedal of the opposite side have been created with a mirror. Illustration 60: Cockpit with gas levers and pedals Illustration 59: Gas lever and pedals 47 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.2.3. Pilot and copilot seats The pilot and copilot seats have many details, all of which have had taken into account. First of all, it has a platform which has been created with a pad. Secondly there have been done the seat itself and the back, which have been designed with the commands pad, edge fillet and shaft. Finally, the rest of details, such as the armrests, two stiffeners located on the back of the endorsement or an inclination regulator, have being modelled by using these same commands. Illustration 63: Cockpit with pilot and copilot seats 4.2.2.4. Copilot handle As it can be seen in the photographs, there is a handle on the left of copilot seat, which could most likely be the handbrake of the wheels of the helicopter. It is a structure composed by plenty of bars and stiffeners, which is connected to some kind of box. Illustration 61: Front view of pilot modelled seat Illustration 62: Back view of pilot modelled seat 48 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 It is worth to mention that the real handbrake is connected to something under the floor, as it can be barely seen in some images that there is a hole on the floor around the brake. However, as it can be considered to be part of a subsystem held inside the floor and it cannot be seen how it is connected, such hole has not been modelled. With the aim of creating the handbrake, the commands used have been pads, edge fillets, mirrors, pockets and rectangular patterns. Illustration 64: Copilot area with modelled handbrake 4.2.2.5. Secondary control panels Although the nomenclature “secondary” control panel is not the most accurate one, from now on all the designed panels in this point will be named that way in order to differentiate them from others. There are only three secondary panels, two of them are inside the lower floor whilst the other one is in the upper side of the aircraft. The left side panels is fixed to the floor, and its shape is not easy enough to be modelled simply with pads, for this reason, it has been necessary to apply some multi-sections solids, defining the desired profiles on the specific points and generating then part of the structure whose modelling is not trivial. The rest of this control panel and the other two secondary panels can be easily modelled with the methods applied along the project until this moment. Therefore, there have been used the commands pad, rib, edge fillet and rectangular pattern to generate them. 49 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 As it was done with the main panel, there have been created grey colored pads which represent the indicators and some buttons or switches. 4.2.2.6. Other seats There are a total number of four seats for the other crewmembers, two of them are in the first floor of the cockpit and the other two are located in the second floor. The modelling of them is simpler than the design of the pilot and copilot seats, however, additionally to the operations pad, edge fillet, pocket and shaft, there have been used a multi-sections solid and a draft in order to represent in the most accurately possible way the original shape of the seats. In the first image of the following two, it is shown a sliding seat. Two of them are sliding seats whilst the other two are not, the only modelling difference is the addition of two sliding guides. The reason why two of the seats have sliding guides and the other two do not is related to the control panel each crewmember has assigned. As it can be seen, the control panels with a higher size have a sliding seat next to them, while the smaller ones are next to a fixed seat. Illustration 65: Secondary control panels Illustration 66: Other seats modelling 50 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.2.7. First floor upper control panel As it can be observed in the ceiling of the photograph of the lower floor, there is a control panel and a structure which covers the whole contour. In the modelling process of such structure, the first step taken was dedicating some time to think about the most suitable way to design it. Even though the contour of the ceiling is defined, there was no chance to make a rib successfully for two reasons, the first, that the curvature of the wall changes along the contour, so any command that uses a constant shape would not be useful. The second reason is that, if it is observed carefully, it can be seen that the height of the structure varies along the contour. Therefore, the decision taken has been doing a multi-sections solid with some guides and a few sketches. During the modelling process a total number of 20 sketches has been created, two per each window. Every sketch contains the shape of the profile of the structure, and is contained in a plane perpendicular to the curvature of the aircraft in that point. With all these sketches, there has only been necessary to create a guide line, defined by the points of the edge of the structure along the wall of the cockpit, and with this guide and the one defined by the contour of the ceiling, there are 20 sketches and 2 guides available, which have been used in a multi-sections solid. It is worth to mention that the first time that this structure was tried to model, there was the intention to use only 10 sketches, the ones related to one side of the cockpit, and then make a mirror to obtain the whole structure. However, for some reason it did not work properly, probably due to some constrains on the guides or the sketches. Illustration 67: Ceiling control panel To do the indicators there has been used the command pad. The switches design, however, have not been that easy to model. As the disposition of the switches has an irregular curvature, it has been necessary to create a line to project over the desired surface, then, a equidistant point command was applied to crate several positions. Finally, it was used, as it was previously explained in other sections, a user pattern on a switcher created with a pad and the set of points designed. 51 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.2.8. Wall to corridor and back side of the stairs At this point, the whole lower floor has been modelled but for the corridor. The first thing that has been created is the wall that separates the corridor and the cockpit itself, moreover, there has been done a hole with the command pocket where the door should be placed. In this section, it has also been modelled what would be the back side of the stairs that lead to the second floor, which occupy most of the width of the corridor, what can be contemplated in the photographs. In order to do this, the stairs have been created with a simple pad, even though at this point there were no stairs on the other side, the modelling of them would be done some steps later. Illustration 68: Back side of the stairs and wall cockpit-corridor 4.2.2.9. Corridor benches Both sides of the corridor have a bench each and have a back attached to a wall. One of them has the back attached to the wall that connects the corridor and the cockpit, the other one is attached to the wall that leads to the main fuselage. The modelling process of the benches has been extremely simple, using only a pad with the desired sketch. Illustration 69: Corridor benches 52 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.2.2.10. Corridor to fuselage wall and door To finish with the corridor design, it has been necessary to create a wall that would correspond with the opposite side of the wall created in the fuselage, which, if it is remembered, left a hole in the area of the door. For this reason, as it was previously said, it is in this section when the door is going to be designed. The modelling of both the wall and the door have been done with the commands pad and wall, the same way that it has been done so many times until this point.It should be mentioned that the door contains a window, so the respective material application has been carried out. Illustration 70: Corridor to fuselage wall 4.2.2.11. Stairs The stairs that communicate the first and the second floor of the cockpit have been modelled by using a pocket in the solid previously created to design the back side of the stairs. At the end of the stairs there is some kind of security structure around the contour of the floor, to model such structure, there have been used the commands pad, pocket, rib and edge fillet. Illustration 71: Stairs modelled 53 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Before explaining the modelling of the elements inside the upper floor it should be mentioned that, as it was previously explained, the modelling of the seats and the panel attached to the wall will be avoided, as the design methodology is the same followed in previous sections. 4.2.2.12. Side structures and binocular system The first thing that can be found once in the upper floor are two big structures, which occupy a great area of the floor, and a binocular system attached to the left structure. Both structures have been modelled with pads and edge fillets. The binocular, on the other hand, has been designed by using pads, pockets and multi-sections solids, in order to obtain the desired geometry. Illustration 72: Binocular system 4.2.2.13. Upper floor control panel As well as it was done with the lower floor, it has been created a main control panel. In order to do so, there have been defined three planes, related to the attitude of the three sections that compose the control panel. With the three planes created, the task has been to design a sketch with the correct geometry and apply on it a pad up to next. Once the main geometry of the three divisions of the panel has been created, there have been modelled several pads on it to simulate the indicators, as it had been done in previous sections with the lower floor panels. The following image shows the panel fully designed, as well as the two seats and the lateral panel modelled, whose modelling has been avoided this time. Illustration 73: Upper floor main control panel 60 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Finally, it is the time to apply some thickness to the generated surface with the command thick surface, leading to the geometry contemplated below. Illustration 82: Modelled tail external geometry 61 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.2. Internal modelling The internal modelling of the tail has been done in the most accurate way with the poor information available, as there are barely no photographs which show the inside of the tail properly, being the image shown below the one that shows it clearer. Illustration 83: Real inside view of the tail As it can be seen, it has been especially difficult to keep a great level of detail with the elements of the inside of the tail, as there are many areas that cannot be seen, like the ceiling or the sides of the tail, and because of the high distance and the darkness, the accuracy of the visible elements is probably not the optimal. However, the rest of the elements which cannot be seen have been estimated, trying to generate a model as accurate as possible. In the image below it is shown the final result of the modelling of the tail, in order to overview it. Illustration 84: Modelled inside of the tail 62 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.2.1. Floor From the starting point of the internal modelling, the empty geometry of the tail, the first step has been to create the floor. To define as accurately as possible the dimensions, the length and inclination of the floor has been determined equalizing it to the length of the opened gate shown in the blueprints. Although it might be possible that the lengths of the floor and the gate are not exactly the same, or the measurements are not the exact ones, it is a good approximation to the reality. The floor has been created using a pad. Illustration 85: Tail floor 4.3.2.2. Side gates formers As it can be seen in the photograph, there seems to be an oblique former which separates the side gates from the floor gate. Behind that oblique former, there are several formers that cover the whole contour of the side gates, but for the first one. All these side gate formers have been modelled in this section. This time, as the curvature of the tail is too strong, it has been impossible to create the formers with pads. Instead, for each former there have been used two planes, with an offset of 20 mm and 30 mm in some cases (which are the estimated widths of the different formers). On these planes it has been created a sketch on each, in which it have been obtained the intersections with the internal geometry of the tail and then there has been defined the shape of the rest of the former. Finally, it has been made a multi-sections solid joining both sketches. 63 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 This same procedure has been followed for each former, leading to the following result. Illustration 86: Side gates formers 4.3.2.3. Oblique former Now it is the turn to create the oblique former it was talked about in the last section. This will be carried out with the same procedure applied with the previous formers, by using the command multi-sections solid. It has been applied a dark grey color to this former in order to differentiate it, and because that seems to be its color in the real tail. Illustration 87: Oblique former 64 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.2.4. Other formers There are only a few formers left to be modelled, however, having a look at the photograph, it seems that the rest of the formers do not cover the whole surface until the floor, but that the extremes of the formers are set by the oblique former, which has been already created. Taking this into account, the procedure followed to create these formers has been using pads, because the curvature at these lengths is low enough to provide the same resulting geometry, and the time and effort spent is much lower by using pads instead of multi-sections solids. Illustration 88: Tail with all formers It is worth to mentions that all the formers crated until now, the ones that belong to the side gates and those created in this section, have been modelled in planes parallels to the plane “XZ”, which are perpendicular to the aircraft axis. This fact, of course, has been an assumption, but as it was said, there is not accurate enough information about the inside of the tail to know the inclination of the formers properly. For the same reason, it has been also assumed that the inclination of the oblique former corresponds with the contour of the side gates. 4.3.2.5. Ceiling structure Attached to the ceiling, there can be found a solid structure at the beginning of the tail. Such structure has been modelled with pads in order to facilitate its creation. Although the curvature of the ceiling is anything but constant, there has been created a first thin pad that would define the down side of the structure, afterwards, the top side of the geometry created has been applied another pad up to surface in the “Z” axis direction. 65 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The result is the one shown in the next image. Illustration 89. Ceiling tail structure 4.3.2.6. Side gates longerons On the photograph there can be seen two longerons attached to the down side of the side gates area, however, it has been assumed that there are two more longerons attached to the ceiling, in line with the ceiling structure defined. To model the longerons, it has been created a line from the former that defines the starting point of the longerons, to the former that marks the final point of them, parallel to the “Y” axis, and it has been projected on the desired points of the surface. Once these curves over the surface have been obtained, the longerons have been created by modelling a sketch with the shape of the longeron profile, and using a rib on such sketch and the projected line. Two of the longerons have been created this way, the other two have been generated with the command mirror. Illustration 90: Side gates longerons 66 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.2.7. Other longerons The rest of the longerons have been modelled in the exactly same way that the previous ones, creating a line, projecting it and doing a rib with the desired sketch. In that case, the ending point is set by the oblique former. The right side longerons have been generated with the command mirror. Illustration 91: Tail with all longerons 4.3.2.8. Tail to fuselage former It can be observed that in the plane that separates the fuselage from the tail, there is a bigger former, as it was not modelled as a part of the fuselage, it will be designed here. It has been created with a pad. Illustration 92: Tail to fuselage former 67 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.2.9. Sliding platform Finally, it has been modelled the platform which can be seen at the end of the floor. It is a sliding platform that relies on the floor when the gates are open. Its main task is to act as a ramp for the vehicles to be able to enter the fuselage. It has been created with the commands pad and pocket. The other sliding platform has been done with a mirror. It is worth to mention too that, although there will not be animations in this project, there have been applied some pockets of 1 mm along the curves that would define the contour of the gates, its use is merely descriptive. Illustration 93: Sliding platform With this, there have been defined all the elements inside the tail. 68 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.3.3. Stabilizers Once again, to model the stabilizers it has been firstly used the module generative shape design, therefore, by creating sketches with the desired profiles and projecting them on the surface of the tail with the command project, there have been defined all the extremes of the stabilizers attached to the tail. If there are created, on the required positions, more sketches that define the opposite side of the stabilizer and some other which define some guides, there can be easily some multi-sections surfaces to obtain the stabilizers. This way, having generated the respective projections, sketches and multi-sections surfaces for each stabilizer, as well as having used the command fill to close the open profiles, the obtained result is shown in the following illustration. Illustration 94: Stabilizers surfaces Once this surface has been achieved, the last task is to give the new obtained surfaces some thickness, what can be done in the module part design with the command thick surface, apply some curvature to the edges generated by using edge fillet and there have also been used some mirrors, as these operations were only applied on one side. 69 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The final result then of the complete tail with its stabilizers is the one see on the image below. Illustration 95: Tail fully modelled 76 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 And now, adding a thickness to such geometry, and seen all the solids created together, the following image represents the obtained result. Illustration 106: Solid wing 4.4.4. Engine details In this section it will be used the module part design in order to generate the air intakes, the nozzles and other details of the engines. In order to create the air intakes and the nozzles, there are going to be applied a set of pockets, which will be painted in black color. To generate the surface of the nozzle, it has been done with a rib, and the resulting geometry has been painted in dark blue. The shape around the intake has been simulated by doing a slot, and the geometries on the back of the engine have been modelled with pads. Illustration 107: Detailed engine 77 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.4.5. Rotors The first thing that has been designed of the rotors is their connection to the engine. It is composed by a set of rods, a wide one in the middle (the rotor mast) and five small rods around it (the control rods). All these rods have been modelled with pads, and such elements are attached to the hub, which has also been created with a pad, and that is supposed to connect the engine and the rotor blades. The beginning of the rotor blades has been modeled like a cylinder with a pad and reproduced with the command circular pattern. Illustration 108: Rotor There are some things worth to be said before explaining how has been generated the rotor blades. First at all, as well as it was done with the wings, the rotor blades have been designed with a NACA profile, but the profile chosen has been the NACA4415, and again, the angle of attack remains constant along the rotor blade length. Illustration 109:NACA4415 profile 78 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 The exposed NACA profile applied to the rotor blade looks like it is shown in the next image. Illustration 110: NACA4415 section Moreover, although only one side of the aircraft is being explained due to the symmetry of the helicopter and all the previously created elements can be mirrored, it has not been done with the rotors for two reasons, the first one is that, as it can be seen in the blueprints, the length of the rotor blades is higher than the distance from the rotor to the symmetry plane of the aircraft, what implies that, if the rotors were symmetrical, the rotor blades would crash. The second reason is that, as it was explained mentioned in the general information about the Mi- 12, one of the rotors rotates clockwise and the other one anti-clockwise, and the rotor blade profile has a leading edge and a trailing edge, so the orientation of the profiles of one rotor is the opposite to the orientation found in the profiles of the other. However, although all these facts have been taken into account in the modelling of both rotors, there will be only explained the creation of one of them, as the procedure is analogue in the other one. Finally, in the blueprints it can be observed that the rotor blades have a certain curvature, in order to model that, it has been created sketch with such curvature, and it has been applied a rib, with the NACA4415 profile as the chosen section to rib, and the created sketch with the defined curvature as the guide. Illustration 111: Rotor (2) 4.4.6. Landing gear and rods The landing gear has been modelled with the exactly same method applied and explained for the wheel of the nose, which consists on using a few pads and a rib, so there will be no further explanations in order to avoid redundancies. Regarding the rods, there can be found several rods connecting the landing gear with the fuselage, the wings, the engines or even the rear side of the fuselage. 79 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 However, there are mainly three kind of rods, and all of them have been defined in a similar way. First at all, to create all the rods, there have been define two points for each rod, one at each endpoint of the rod to be designed. Once the two points have been created, it is time to generate a line which has those points as endpoints. Now, depending on the kind of rod required, there have to be one (in the middle of the line), two (in both endpoints) or three (in the three mentioned positions) planes. For the rods of the type 1 (1 plane), there will be no variation on the size of the profile along the rod, so it will be modelled with a single pad up to both surfaces. For the type 2 rods, the rod will be wider in one extreme and thinner in the other one, so for this kind of rods there have been designed two different profiles, one at each endpoint (and each one with a different size), and it has been applied a multi-sections solid to them. Finally, the third type of rods is a mixture of the other two, most of the rod has a constant section, but it gets thinner in the endpoints. To recreate these rods, it has been modelled a profile in each plane, being the one of the middle larger than the others, it is applied a pad to the bigger profile, mirror extended and up to a certain distance from the endpoints, now it has been used the command multi-sections surface to join the resultant extremes of the pad with their respective endpoint sketches. Once the landing gear and the totality of the rods have been modelled, the result is the following one. Illustration 112: Landing gear and rods 4.4.7. Fuel tanks The only remaining elements to be modelled are the fuel tanks. The fuel tanks have been modelled with a pad and some edge fillets, regarding the rods that join the fuel tank and the fuselage, each of them have been designed like it was explained in the previous section, and all of them are “type 1” rods, using the same nomenclature. 80 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 It is worth to mention that the connection from the fuel tanks to the engines has not been modelled. The fuel tanks are connected to the fuselage, so the fuel transport system is probably inside the body, and it is one of the areas that has not been modelled due to the lack of information. A photograph of a fuel tank can be seen below. Illustration 113: Fuel tank Therefore, the final result, with all the details and outer structures included, can be seen in the next image. Illustration 114: Outer systems and structures 81 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 82 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 4.5. Mi-12 assembly By this point, all the parts in which the aircraft has been divided are completely modelled, both externally and internally, and with a great level of accuracy. It is time then to create a product, what will make it possible to join the different part designs previously created. In order to do so, the first part called from the library has been the fuselage, and its position has been fixed because, as it was said, the whole aircraft has been built around the body. Afterwards, the rest of the parts have been added to the fuselage, imposing contact and parallelism constrains between them and the fuselage, not allowing any kind of displacement. Illustration 115: Front view of the aircraft Illustration 116: Back view of the aircraft 83 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 117: Plant of the aircraft In the next images it has been put the created model of the Mi-12 in different backgrounds, in order to see how it would be in the reality if the 3D model was manufactured. Illustration 118: Rendered image 1 84 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5 Illustration 119: Rendered image 2 Illustration 120. Rendered image 3 85 Modelling and virtual recreation of the helicopter Mil V-12 with Catia V.5