Unmanned air vehicle (UAV) Airfame Design and Manufacture

National University of Singapore 10 UAV DESIGN AND MANUFACTURE U067782B ZHANG XUETAO 2 | Page Table of content Summary 3 Introduction 4 UAV fuselage design 6 Aircraft shape and aerodynamics of fuselage 7 Aircraft structure analysis 12 Engine connection 12 Wing connection 16 Material selection 18 UAV Fuselage manufacture 22 Vacuuming forming 22 Conclusion 29 Recommendation 30 Reference 32 Appendix 33 3 | Page SUMMARY The first part of the report is concentrated on UAV fuselage design. It consists three sections: aerodynamics, stress analysis and material selection. The fuselage shape must be such that separation is avoided when possible. That’s where the aerodynamics of the fuselage design’s core. By designing the ratio and shape of the UAV nose and tail cone, the ultimate goal is to reduce as much drag as possible and provide lifts. We must be convinced that a manoeuvre always involves acceleration, turning, deceleration, all of which will put the UAV under high loads, that’s why the stress analysis is so important here. By referring to the thorough stress analysis, theoretically the UAV is safe to fly under any conditions. Material is always so important for aircrafts that in reality, all the aircrafts has been built by most expensive industrial materials, like carbon fibers, carbon steels, nickels, molybdenum, etc. For this UAV design, no much vibration, corrosion, noise would be taken into consideration. What’s more, the stress involved is not as high as the real commercial aircraft, so cheaper and realistic materials should be studied. In fact, after a comprehensive study about wood, Styrofoam, plastics, steel and carbon fibers, PVC is finally chosen as the main fuselage material. The second part of the report mainly introduces an industrial process—vacuuming forming and its implementation in this UAV fuselage design. Some advantages and disadvantages are discussed in this part. 4 | Page Vacuum forming is one of the methods using thermoforming treatment. Besides the fact that vacuum forming can make exact shape as the mould, it also take less pain to build the station and take less time to produce one piece of prototype. However, several disadvantages exist. The whole process should been monitored very carefully since toxic gas would be produced if the plastic is overheated. Also in lab scale, it is always very hard to build a station large enough for the overall design and the prototype is very hard to modify as well. 5 | Page 1. INTRODUCTION The purpose of this project is to design and manufacture an Unmanned Air Vehicle (UAV). As a group project, it requires four students to design and/or build wings, fuselage, engine and optimization. This report is the final report for the fuselage design and manufacture. There are numerous interesting books on the history of aircraft development. This section contains a few additional notes relating especially to the history of aircraft aerodynamics along with links to several excellent web sites. (Refer to appendix 1). However, there are very few topics relating to UAV design and manufacture. This report gives students a comprehensive overview and understanding of UAV fuselage design and manufacture. According to the optimization, this UAV is designed to maximize the endurance. In order to achieve the design goal, besides the wing and propulsion, the fuselage gives great contribution as well. The following parts have two main sections: UAV fuselage design and manufacture. In the design part, aerodynamics designs including nose and tail cone together with stress analysis and material selection are elaborated. In the manufacture part, a newly and practical industrial process—vacuum forming is introduced and implemented. 6 | Page 2. LITERATURE REVIEW A search for “nose fineness ratio” produced 1240 journals from Engineering Village and 480 from Web of Science. Further search for “aerodynamic nose fineness ratio” produced 188 from Engineering Village. 80 out of these 188 journals have been reviewed. Below are the summary of those researches. Shu Xin-wei and Gu Chuan-gang (2006) did researches on “numerical simulation on the aerodynamic performance of high-speed maglev train with streamlined nose”. They indicated that with comparison and analysis of the results of the five different configurations, regularity that its aerodynamic performance changing with its aerodynamic configuration was drawn. When the other parameters are the same, the aerodynamic drag and lift decrease with the length of the streamlined nose shapes extending; when the length of the streamlined nose shapes is almost the same, the aerodynamic drag of the front car of the protruding longitudinal profile is less than that of the concave, while that of the rear car is the contrary; the aerodynamic drag of the middle car varies within a small range, the aerodynamic lift of the rear car is greater than that of the front one; and the total aerodynamic lift of the three cars of the protruding longitudinal profile is greater than that of the concave. Ota, Terukazu (1983) worked on the project of nose shape effects on turbulence in the separated and reattached flow over blunt flat plates. He found that the nose shape has a strong influence on the turbulence features in the separated and reattached regions and even far downstream from the reattachment point. 7 | Page Goodson, K. W (1958) wrote of journal named Effect of Nose Length, Fuselage Length, and Nose Fineness Ratio on the Longitudinal Aerodynamic Characteristics of Two Complete Models at High Subsonic Speeds. He discovered that the stability for all model configurations showed substantially the same variation with changes in forebody area moment. The forebody changes did not alter the angle of attack at which an unstable break occurred in the moment contribution of the T-tail but did alter somewhat the magnitude of the instability. A search for “vacuum forming” produced 820 journals from Engineering Village and 210 from Web of Science. 40 out of these 1130 journals have been reviewed. Below are the summary of those researches. Campo, E. Alfredo (2008) wrote in his journal “Polymeric Materials and Properties” that all PVC compounds require heat stabilizers to allow processing without degrading and discoloring the polymer. Plasticizers are added to increase the flexibility of the compound. They can also improve the heat stability or improve the flame retardancy of the compound. Fillers are used to reduce the cost, improve dimensional stability, stiffness, and impact strength. PVC is a recyclable commodity thermoplastic material of large consumption by the building and construction industry. PVC is popular because of its excellent impact, wear, chemical, and UV resistance. PVC is used in a large variety of end products such as flooring, garage doors, windows frames and profiles, siding, tubing, and connectors. These products 8 | Page are commonly available in standard sizes and shapes, low cost, and easy to work with (weld, repair, and paint). Fagence, S.W. and Garvin, W.Barry (1973) discussed the machines and their operations (loading the sheets, clamping, heating, interlocking, drawing, pre- stretching, etc); mold design; and mold cooling in the large piece of vacuum forming process. He also stated that a definition of 'large sheet' could be a 'sheet in excess of 16 sq. ft'. Wilhelm R (1971) stated in his report “Vacuum forming of thermoplastics”, that although several materials can be used for the mold, for instance epoxies and silicone rubber, metal forms were mostly used, particularly for long production needs. Decoration and joining by adhesive bonding and HF welding of PVC vacuum formed products were discussed. Breuer, Heinz (1977) indicated in his journal “Importance of Vacuum Technology for Extrusion of Plastics as Exemplified by PVC Processing” that the processing of powdered thermoplastics - particularly PVC in the form of compounds including common stabilizers - on twin-screw extruders was widely accepted quite some time ago. The more recent development in the sector of PVC film for food packaging has called the attention to compact extrusion lines with small sized calenders. Here, however, single-screw and planetary roller extruders with sheering dies rather than twin-screw extruders are used as plasticizing equipment. For improving the profitability of these techniques as well as the quality of the finished products, the extruders are fitted with vacuum-assisted feed hoppers. Apart from air and moisture, 9 | Page the vacuum technology from which the closed system of the vacuum type twin- hopper venting unit with the extruder has been derived, also permits the removal of other excess gases and vapors and, not last, the residual VC content from the PVC melt. Ian C. McNeill, Livia Memetea and William J. Cole (1995) discovered in their study of “products of PVC thermal degradation” that PVC shows two stages of degradation: during the first stage, between 200 and 360 °C, mainly HCl and benzene and very little alkyl aromatic or condensed ring aromatic hydrocarbons are formed. It was evaluated that 15% of the polygene generates benzene, the main part accumulating in the polymer and being active in intermolecular and intermolecular condensation reactions by which cyclohexene and cyclohexadiene rings embedded in an aliphatic matrix are formed. Alkyl aromatic and condensed ring aromatic hydrocarbons are formed in the second stage of degradation, between 360 and 500 °C, when very little HCl and benzene are formed. In this stage the polymeric network formed by polyene condensation breaks down in the process of aromatisation of the above C 6 rings. The mechanism of benzene formation at different temperatures was considered. 10 | Page 3. UAV FUSELAGE DESIGN The design of the fuselage is based on payload requirements, aerodynamics, and structures. The overall dimensions of the fuselage affect the drag through several factors. Hemida, Hassan and Krajnovic, Siniša (2010) Stated that fuselages with smaller fineness ratios have less wetted area to enclose a given volume, but more wetted area when the diameter and length of the cabin are fixed. The higher Reynolds number and increased tail length generally lead to improved aerodynamics for long, thin fuselages, at the expense of structural weight. Selection of the best layout requires a detailed study of these trade-offs, but to start the design process, something must be chosen. This is generally done by selecting a value not too different from existing aircraft with similar requirements, for which such a detailed study has presumably been done. In the absence of such guidance, one selects an initial layout that satisfies the payload requirements. In this UAV fuselage design, the payload requires a fuselage being able to hold a camera, batteries, servo, and targeting ball. Except the payload requirement, other considerations are: • low aerodynamic drag • minimum aerodynamic instability • ease of assembly and disassembly of fuselage • structural support for wing and tail forces acting in flight, which involves simple stress analysis for the entire fuselage [...]...3.1 Aircraft Shape and Aerodynamics of Fuselage 3.1.1 Aircraft Nose and Tail Cone Design The fuselage shape must be such that separation is avoided when possible This requires that the nose and tail cone fineness ratios be sufficiently large so that excessive flow accelerations are avoided The aircraft fineness ratios are defined as length divided by diameter, which including nose fineness ratios and. .. The fuselage design focus on aerodynamics, stress analysis and material selection And the manufacture part focuses on vacuum forming process Based on several researches on nose and tail cone fineness ratio as well as shape of fuselage, this UAV fuselage is designed as ellipsoid, as the nose and tail cone ratio as 1:2 Stress is calculated on mainly the steel plate attached to the engine and the carbon... aerodynamic centre, which is design to make sure of the aircraft stability and easily maneuverability, and based on the fact that the tail of the plane is relatively high, the batteries and camera should be put into the very front to counter the weight As such, the nose should be designed so as to have enough space to hold the payloads at the very front That’s the main reason of this design Fineness ratio... method is chosen to manufacture the UAV fuselage, not because it is the requirement of this project, but mainly, it is the only way to manufacture fuselage by plastics using the ideal design Despite the disadvantages, vacuum forming, as a commonly used industrial process, provide a practical way to the fuselage into reality 35 | P a g e 5 CONCLUSION This UAV fuselage design and manufacture report has... considerations in real airplane consideration The profile of current designed shape is one-half of an ellipse, with the nose and tail fineness ratio 2 R=4.5cm, L=18cm 13 | P a g e R=4.5cm L=18cm In this UAV design, one of key factors in UAV fuselage shape design is the payload According to the payloads weights, centre of gravity as well as the attribution of the different parts, the width, namely the aircraft lateral... weight-to-stress ratio, and resistant to corrosion or stress concentration, etc, plastics are the best choice, and vacuum forming method is chosen for plastics’ manufacture 23 | P a g e 3.3.2 Selection of Plastics For the UAV fuselage, from all the possible plastics, PVC is chosen It has strong, tough thermoplastic with good transparency in thinner gauges, good chemical and fire retardant properties and highly... 2.60 1 1 2 3 2.15 4 3 PVC 60 3 PC 120 0.5 • The standard thickness for the heating is 2mm More details about vacuuming forming of PVC would be discussed in the manufacturing section of the later part 25 | P a g e 4 UAV Fuselage Manufacture 4.1 Vacuum forming The whole fuselage requires vacuuming forming as a tool to manufacture two parts: aircraft nose and the tail cone Vacuum forming is one of the methods... below, we could make the exact shape as the moulds, which is one of the key factors in this UAV design Since the design of the fuselage has very restricted requirements, there are only two possible economic ways to do that: clamping and vacuum forming For student lab scale, it would be practical to design and build the vacuum forming station Secondly, it is relatively easy to use vacuum forming method... table, frame and the oven! As shown below, the frame is designed to have only 25*20cm effective working area Vacuum table has 20*15cm effective working area, and the oven has 30*25 effective working areas In order to continue this project with this method, some modifications have been made In order to make the whole piece of nose and cone at one time, two identical parts had been divided and glued together... priority of the design is to fulfill the payloads’ requirement The final design is as followed: design parameters design value fuselage length . this project is to design and manufacture an Unmanned Air Vehicle (UAV). As a group project, it requires four students to design and/ or build wings, fuselage, engine and optimization. This report. to UAV design and manufacture. This report gives students a comprehensive overview and understanding of UAV fuselage design and manufacture. According to the optimization, this UAV is designed. UAV DESIGN AND MANUFACTURE U067782B ZHANG XUETAO 2 | Page Table of content Summary 3 Introduction 4 UAV fuselage design 6 Aircraft shape and aerodynamics of fuselage 7 Aircraft