Development of a Cold Gas Propulsion System for the ... - SSL - MIT

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6.3.1 Thruster Identification To track the performance of individual thrusters, an identification system involving letters and numbers was developed. The four corners of the TALARIS vehicle were designated as A, B, C, and D, and the thruster pair nearest to each corner was also identified by that letter. These pairs were called station pairs. Each individual thruster was also given an identifying number from 1 to 8. All vertical thrusters had odd numbers, and all horizontal thrusters had even numbers. Numbering proceeded around the vehicle from A to D, so the vertical thruster in station pair A was thruster 1, the horizontal thruster in station pair A was 2, the vertical B thruster was 3, the horizontal B thruster was 4, etc., as shown in Figure 6-6. Figure 6-6. Identification of thrusters by number and letter. Body coordinate axes also shown [38]. 6.3.2 Static Test Stand CGSE thruster performance in the full flight system was measured using a 6-axis load cell, which could measure forces along three orthogonal axes as well as moments about those axes. For these measurements to be accurate, the TALARIS vehicle had to be entirely supported by the load cell with no 90
other constraints. This was difficult because the TALARIS vehicle was irregularly shaped and the load cell was comparatively small. Furthermore, for the easiest interpretation of the data produced, the load cell had to be placed beneath the center of the vehicle with its axes aligned with those of TALARIS. In order to fulfill all these requirements, a two-part static test stand was built from aluminum T-slot framing. One part was a cradle, which firmly supported TALARIS on four posts, each attached to a hard mount at the center of one of the sides of the vehicle. These four posts attached to crossbars which met at a central plate beneath the TALARIS hopper. The second part of the static test stand was a base with widespread legs which were weighted down to hold the stand stationary. These legs also came together at a central plate. Then, the 6-axis load cell was bolted to each of the two central plates, making it the only connection between the cradle and the base as shown in Figure 6-7. Figure 6-7. Static test stand for CGSE flight system characterization. The measurement axes of the load cell were aligned with the TALARIS body coordinate axes shown in Figure 3-2 and Figure 6-6. Thus, without having to move or rotate the vehicle in any way, thrust measurements could be taken for all eight CGSE thrusters. Data from the load cell was collected with the RIO, so it had the same timestamps as the thruster commands, which was especially important in the analysis of the results of the pulsed operation tests. 91
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Development of a Cold Gas Propulsio
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Abstract The TALARIS (Terrestrial A
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Table of Contents List of Figures .
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7 Ongoing and Future Work .........
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Figure 6-6. Identification of thrus
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Notation Acronyms and Abbreviations
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N newton Pa pascal psi pounds per s
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1 Introduction The TALARIS (Terrest
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the idea of hopping was born, and i
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However, as stated before, this doe
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Figure 2-3. Diagram of ACAT lander
Page 29 and 30:
An alternate approach to resolving
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accurate conditions for testing GNC
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Ballistic hops tend to use less pro
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2.3.2 Comparison of Cold Gas and Mo
Page 37 and 38:
Handling propellant There are sever
Page 39 and 40:
and if the cold gas system was foun
Page 41 and 42: 3 TALARIS CGSE Design Framework Aft
Page 43 and 44: Figure 3-1. Scaling of TALARIS terr
Page 45 and 46: (3) Providing attitude control Ther
Page 47 and 48: Figure 3-2 also shows the body coor
Page 49 and 50: 4 Modeling and Flow Control Compone
Page 51 and 52: 4.1.2 Rocket Propulsion Equations L
Page 53 and 54: variables in equation (4-8) deal wi
Page 55 and 56: equations. Equation (4-10) was then
Page 57 and 58: that of helium (0.227 MPa = 32.9 ps
Page 59 and 60: thruster solenoid valve, and chambe
Page 61 and 62: where
Page 63 and 64: discussed later in section 6.3.4, t
Page 65 and 66: The flight profile begins with maxi
Page 67 and 68: hop, any given valve or regulator o
Page 69 and 70: esponse time was an important perfo
Page 71 and 72: directly opens and closes the main
Page 73 and 74: If 1D isentropic flow is assumed, t
Page 75 and 76: 5 Single-Stream Component Testing A
Page 77 and 78: the solenoid valve, and a pressure
Page 79 and 80: As indicated in Figure 5-3, initial
Page 81 and 82: Figure 5-5. CGSE high side as const
Page 83 and 84: Figure 5-7 illustrates several aspe
Page 85 and 86: 6 Full Eight-Thruster Flight System
Page 87 and 88: Figure 6-2. TALARIS CGSE assembled
Page 89 and 90: stream tests revealed that changes
Page 91: Figure 6-5. Original CGSE control c
Page 95 and 96: variables (such as number of thrust
Page 97 and 98: One solution to this problem would
Page 99 and 100: One of the characterization tests w
Page 101 and 102: or more thrusters were firing toget
Page 103 and 104: Table 6-3. Valve timing metrics dur
Page 105 and 106: Figure 6-11. Redesigned CGSE contro
Page 107 and 108: The imaginary simplified thruster c
Page 109 and 110: traverse phase of a hop and involve
Page 111 and 112: Figure 7-3. GNC data from 3-DOF tes
Page 113 and 114: Tests on this vertical stand demons
Page 115 and 116: control the belay line can be put u
Page 117 and 118: accounting for changes in thrust le
Page 119 and 120: development under the supervision o
Page 121 and 122: documenting progress takes time whi
Page 123 and 124: were encountered, it was harder to
Page 125 and 126: [10] Bryant, K. M., Knight, C. J.,
Page 127 and 128: [31] Canadian Centre for Occupation
Page 129 and 130:
[50] ISA - The Instrumentation, Sys
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