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

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were run with the apparatus set up to produce the maximum single-stream thrust of 40 N. The results of these tests are presented in Figure 5-8. Figure 5-8. Impulse vs. pulse width for single-stream thruster producing 40 N maximum thrust [38]. In Figure 5-8, each point is the average of at least ten measurements, plotted at the commanded pulse width and average impulse measured. The error bars in the x direction represent the range of thruster actuation times actually measured, and the error bars in the y direction are the standard deviation of the impulse measurements. As shown in Figure 5-8, the relationship between impulse and pulse width was linear down to a commanded pulse width of approximately 20 ms, where the impulse bit then leveled off at approximately 1 N·s. However, for consistent control performance, the minimum impulse bit was defined by the minimum pulse width for which the actual measured impulse equaled the commanded impulse. Because of the relatively large uncertainties, the minimum pulse width was taken to be 40 ms, and the minimum impulse bit delivered by the single-stream thruster was 1.6 N·s. Overall, the results of the single-stream component tests were very positive. The 40 N maximum thrust produced was at the high end of the design goal laid out in section 3.1.4, and it was believed that the 40 ms minimum pulse width and 1.6 N·s minimum impulse bit would allow the CGSE to control the TALARIS hopper. Thus, the flight regulator and thruster solenoid valves appeared to be sized correctly, and the next step was to ensure that they would operate satisfactorily in the full eight-thruster flight system. 82
6 Full Eight-Thruster Flight System Due to the strong effect of feed line geometry on thruster performance observed in the single-stream component tests, it was decided to proceed not only to testing all eight CGSE thrusters at once, but to finalizing the configuration of the entire system. The only way to accurately characterize the performance of the CGSE was to test it as it would be flown. 6.1 Hardware Construction The construction of the full flight configuration of the CGSE coincided with a general upgrade of the TALARIS structure. The first-generation TALARIS hopper constructed by the spring 2009 16.83/89 class (Figure 6-1) had an aluminum frame and a Plexiglas deck which was becoming too crowded as changes and additions were made to the avionics and the other vehicle subsystems. Figure 6-1. First-generation TALARIS vehicle (T-1), which did not include the CGSE. 83
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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
Page 23 and 24:
the idea of hopping was born, and i
Page 25 and 26:
However, as stated before, this doe
Page 27 and 28:
Figure 2-3. Diagram of ACAT lander
Page 29 and 30:
An alternate approach to resolving
Page 31 and 32:
accurate conditions for testing GNC
Page 33 and 34: Ballistic hops tend to use less pro
Page 35 and 36: 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: Figure 5-7 illustrates several aspe
Page 87 and 88: Figure 6-2. TALARIS CGSE assembled
Page 89 and 90: stream tests revealed that changes
Page 91 and 92: Figure 6-5. Original CGSE control c
Page 93 and 94: other constraints. This was difficu
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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