unmanned air vehicle (uav) airfame design and manufacture.pdf
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National University of Singapore
UAV DESIGN AND MANUFACTURE U067782B
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Table of content
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
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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. Thats
where the aerodynamics of the fuselage designs 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,
thats 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. Whats 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 processvacuuming
forming and its implementation in this UAV fuselage design. Some advantages and
disadvantages are discussed in this part.
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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.
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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 processvacuum forming is
introduced and implemented.
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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.
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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
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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 an