Master Thesis - OUFTI-1

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These thermostats were chosen because: • They have very small dimensions (diameter = 6.68 mm and thickness = 2.04 mm). • They are lightweight (mass = 0.2 g). • They are space-qualied (conform to qualication MIL-S-24236/13). In our case, the selected thermostat is an open-on-rise one. The mechanism of these thermostats is the following one: • When the temperature of the batteries passes under 7.2 ◦ C, the thermostats supply the heaters. This particular value was chosen by the THER subsystem to avoid that the temperature of the batteries becomes negative. Indeed, the tolerance guaranteed by the manufacturer is 4.4 ◦ C, and the rst available value above this one is 7.2 ◦ C (4.4 ◦ C is also available but, in this case, the non-negativity of the batteries' temperature could not be assured at each time). • They continue until the temperature of the batteries pass above 23.9 ◦ C (± 4.4 ◦ C). At this moment, the thermostats open the circuit and the heaters are no longer supplied. Now, the problem is to determine how many thermostats are necessary to obtain a reliable control system. Dierent solutions were investigated: • The rst idea was to use four thermostats per battery. These ones will be connected 2 by 2 in series, and the two parts will be connected in parallel. This solution is illustrated in Figure 3.12 (where the B stands for Battery, H for Heater and T for Thermostat). Figure 3.12: Connection with four thermostats This solution had to be given up because it is too expensive for this particular application. 57
• So, it was decided to use two thermostats per battery (to prevent a non-uniform distribution from the temperature inside the battery). These ones will be placed on the face −Z of the batteries (which corresponds to the side of the cover). So, a notch must be manufactured on the cover. Now, it must be decided how these thermostats will be connected together. The Table 3.5 summarizes the dierent types of available congurations and problems that can occured. Thermostat breaks open Thermostat breaks closed Connection Heater will never be supplied so, The second thermostat will work in series the battery will freeze as if it was alone Connection The second thermostat will work Heater will be continuously supplied so, in parallel as if it was alone the battery will burn out Table 3.5: Dierent available congurations and problems for thermostats In accordance with these observations, it was decided to connect them in series. Indeed, for the connection in parallel, the second problem causes a constant supply of the heater. In this case, all the power available inside the satellite would be used to supply this heater, and the entire satellite would be lost. With the connection in series, in the worst case, one battery freezes but the rest of the satellite is safe. 3.7.3 Thermal insulator Aluminum, which is the material chosen to manufacture the battery support, is a thermal conductor. So, to avoid all waste of energy during the batteries' heating, a thermal insulator must be placed between the batteries and their support. The selected insulator is a polyester netting, illustrated in Figure 3.13. Figure 3.13: Thermal insulator: Polyester netting This type of insulator is typically used as a spacer material to minimize conductive heat transfer between Multilayer Insulation (MLI) blanket layers. The netting material is chosen for its low outgassing characteristics and is specially cleaned to assure that it is residue free [43]. One layer of insulator will be placed on each side of the batteries (the layer on the cover side will surround the thermostats). 58
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University of Liège Faculty of App
Page 3 and 4:
Abstract OUFTI-1, standing for "Orb
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3.4 Initial idea . . . . . . . . .
Page 7 and 8: List of Figures 1.1 The Pumpkin's C
Page 9 and 10: 4.18 MAC matrix using the simple me
Page 11 and 12: List of Acronyms ADCS Al AlNiCo ASI
Page 13 and 14: Thesis outline This thesis focuses
Page 15 and 16: of larger satellites. So, the CubeS
Page 17 and 18: 1.2 OUFTI-1 project 1.2.1 Genesis O
Page 19 and 20: • XatCobeo (Vigo - Spain): Develo
Page 21 and 22: Chapter 2 OUFTI-1: Flight system co
Page 23 and 24: Figure 2.2: Product tree of OUFTI-1
Page 25 and 26: 2.3.2 Solar panels The armor panels
Page 27 and 28: • We do not want to drill or manu
Page 29 and 30: In our case, because of the limited
Page 31 and 32: Figure 2.13: Magnetic eld obtained
Page 33 and 34: Figure 2.17: Pictures of the ADCS c
Page 35 and 36: consider the possibility of oshorin
Page 37 and 38: Figure 2.20: Exploded view of OUFTI
Page 39 and 40: I xx , I yy and I zz are called the
Page 41 and 42: Subsystem: Structure & Conguration
Page 43 and 44: Subsystem: Thermal Control Parts Co
Page 45 and 46: Chapter 3 Design of a new support f
Page 47 and 48: Figure 3.3: Batteries during and af
Page 49 and 50: The concept is the following one: F
Page 51 and 52: A test under vacuum conditions was
Page 53 and 54: Thermal Expansion (CTE) of the mate
Page 55 and 56: Figure 3.9: Classication by density
Page 57: The last property to determine is t
Page 61 and 62: is to prevent the batteries' bulge.
Page 63 and 64: • Then, the thermostats, that wil
Page 65 and 66: Figure 3.23: Schematics of the cove
Page 67 and 68: • Other components, including the
Page 69 and 70: 3.9.3 Dynamic behavior Finally, it
Page 71 and 72: 3.10 Summary Through this chapter,
Page 73 and 74: Chapter 4 Electronic cards dynamic
Page 75 and 76: Figure 4.1: Example of manufacturin
Page 77 and 78: Figure 4.4: Illustration of the exp
Page 79 and 80: Figure 4.5: MAC between the two mod
Page 81 and 82: • Global mass/stiness smearing me
Page 83 and 84: 4.2.6 Modeling of the chassis A gen
Page 85 and 86: Q = ω k = 1 ω b − ω a 2 ζ ⇒
Page 87 and 88: Their study was based on the fact t
Page 89 and 90: Figure 4.14: Example of spacecraft
Page 91 and 92: Figure 4.15: Location of measuremen
Page 93 and 94: Figure 4.18: MAC matrix using the s
Page 95 and 96: 4.3.6 Application of the local mass
Page 97 and 98: ρ P C 104 connector = 10.12 × 10
Page 99 and 100: According to this particular shape,
Page 101 and 102: This is due to the fact that this c
Page 103 and 104: environment. Then, this model is ex
Page 105 and 106: 5.2.4 Antenna support For the anten
Page 107 and 108: Components Young's moduli (GP a) Po
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Components Young's moduli (GP a) Po
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5.3 Static analysis As described in
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Figure 5.9: Illustration of the com
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Figure 5.11: Maximal Von Mises stre
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Figure 5.12: First mode of OUFTI-1
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Figure 5.15: Precise PSD of Vega [5
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Chapter 6 Conclusions This master t
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provided for each method used. We h
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last versions of the Verication Con
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[13] Ph. LEDENT. "Design and Implem
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[40] "Dejond - Aluminum Catalog ".
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Appendix A Schemas of solar panels
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Appendix B Schemas of electronic ca
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Appendix C Fixations of the endless
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Appendix D Datasheet of the battery
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Master Thesis - OUFTI-1

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