The design report

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Fuselage fabrication 5.2 Since there were two fuselages, it was decided that it would be wise to start with the first one and get familiarised with it, then start with the second one. This is very useful as there may be mistakes during manufacture the first fuselage and the mistake could actually be corrected without wasting additional material. A couple of mistakes were found while making the first fuselage. For example, the two top plates were made exactly the same initially in CATIA. During the fabrication process of the second fuselage, we found that the bottom plate did not fit as there were locking mechanisms stopping it from clicking in. The bottom top plate was then cut out so that it could easily slide through the ribs and not click in like the top one. Realisation occurred at the time about the fact that processes in CATIA does not necessarily ensure fabrication success The order of the fabrication was fairly simple. CATIA files had to be converted into .dxf files and rearrange all the parts in AutoCAD to fit the given dimensions of different materials that we were using. The files were then run in the laser programme and the laser will cut the exact part out for us. The problem with this part is that some of the planks of wood were not entirely flat so there were minor errors when the laser machine was cutting the parts. Those errors were small enough to neglect so it did not cause a big problem. It had to be ensured that tiny parts were required to cut, as it might fall through the gaps under the planks. It is best to slide a thin sheet of used balsa to stop that from happening. The fuselage design consisted on many interlocking parts to ensure all connectivity was well secured. Gluing was only a secondary process of connection and only in place to avoid slipping. The design of the fuselage had readymade slots for everything to be locked together so figuring out the actual position of each rib was not at all a problem. Extra effort was taken into strengthening the connections, for example, the centre plate and the longerons that had to be split into two due to the restriction of length were to sandwich it with two carbon strips on the joints. That would have ensured that the joining of two would not split apart during flight or when carrying a load. After gluing everything into place, the fuselage was to be left overnight to dry completely. There were three different types of glue that we used (AB Glue, Superglue, PVA Glue). Each glue needed different amount of time to dry so it all depends on which glue was used. PVA glue was the glue used for parts that did not do heavy duty work and superglue was the glue when you needed something to be in place instantly while AB glue was the strongest of all and it was to be used on parts the take heavy loads.
When the skeleton of the fuselage was ready, the balsa skin was ready to be placed on it. 1.5mm balsa sheet was used as the skin of the fuselage there was no 1mm balsa sheet available. To prevent the balsa sheet from cracking, they had to be placed or submerged in water first. The balsa in water technique worked great on the fuselage as we had a circular fuselage. It would be really difficult to bend the balsa sheet if it was just a dry sheet. After bending the fuselage into shape, the balsa is left to dry up and take the shape of the fuselage, and then we stick it on. We deliberately left two major parts of the balsa not completely stuck onto the fuselage as we wanted to have an easy access into the fuselage for maintenance purposes. The whole top part before the top plate was left open with a balsa sheet acting as a door and half of the side of the fuselage under the wing was left open as they are the most crucial part of the design and requires high maintenance. After all the balsa skin was done, thermal shrink films were ironed on top of the balsa skin for finishing touch. Wing fabrication 5.3 Wing fabrication was started by cutting all parts (ribs, spars, webs, rods etc.) and labelling them. Once all the required parts were cut and collected, the process of sticking everything together was started. AB glue was used for most of wing structure however superglue was occasionally used. A total of 5 webspars were used and firstly all the ribs were glued and locked in. Webspars ensured that the ribs couldn’t move in any direction. The only problem was that the wood used was not perfectly straight which meant that some ribs and webspars had a bend in them. The bending was corrected once all rods and spars were glued on. After the webspars, spar caps at 30% at top and bottom of the ribs were glued on. The sparcaps run through most of the wing structure which meant that 2 rods had to be joined due to lack of availability of longer rods. After this, front spar was glued on and it was also done by joining 2 pieces. Figure 5.3.101
Page 1 and 2: EP-UAV Project 2009 iSpy Kate Rietd
Page 3 and 4: Preliminary and Detailed Design 4 S
Page 5 and 6: Executive Summary 1 iSpy is a twin
Page 7 and 8: Design Requirements and Objectives
Page 9 and 10: Initial Sizing 3.1.2 Estimating air
Page 11 and 12: Airfoil design 3.1.4 Wing: Before t
Page 13 and 14: Tail: A symmetric airfoil with a th
Page 15: Empennage design 3.1.6 The dimensio
Page 19 and 20: Pod Layout 3.1.9 The pod of the air
Page 21: Weight estimation and Centre of Gra
Page 26 and 27: Figure 3.2.303 - Stability axis der
Page 30 and 31: CAD definition of the concept 3.2.5
Page 32 and 33: Figure 3.2.505: The vertical tail F
Page 34 and 35: Preliminary and Detailed Design 4 S
Page 36 and 37: Figure 4.1.109 Figure 4.1.110 The c
Page 38 and 39: Material type was chosen for each c
Page 40 and 41: The nose section of the fuselage co
Page 42 and 43: This part of the fuselage is the mo
Page 44 and 45: Empennage structure 4.1.3 Prelimina
Page 46 and 47: An ‘L’ shaped support was also
Page 48 and 49: Landing gear 4.1.5 Initial stages o
Page 50 and 51: Pod Structure 4.1.7 Figure 4.1.701-
Page 54 and 55: The servo holder plates in front of
Page 56 and 57: Landing gear fabrication 5.5 The de
Page 58 and 59: Fabrication of Pod 5.6 Like the fus
Page 60 and 61: Control surface fabrication 5.9 Ail
Page 62 and 63: Note: The weights taken after fabri
Page 64 and 65: It was here that the first problem
Page 66 and 67: Flight Test 6.2 The flight test aim
Page 68 and 69: Appendix 7 Appendix A - AVL files i
Page 70 and 71: TRANSLATE -0.450 0.384 0.00 # BFIL
Page 72 and 73: CLARK YM-15 - Re = 250000 Alfa Cl C
Page 74 and 75: Appendix C - Preparation of materia
Page 76 and 77: Appendix D - Control surface sizing
Page 82 and 83: Conceptual Design Preliminary Desig

The design report

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