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

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5.3 Results Originally, it was planned that pressure and temperature data collected in the single-stream tests would be used to validate parts of the MATLAB thermodynamics model. Unfortunately, although pressure data was acquired successfully, the thermocouples used in the single-stream tests were found to have a very slow response time, taking more than a full minute to register a change from 0°C to 100°C when moved from a glass of ice water to a glass of boiling water. This is probably due to the large fittings in which the thermocouples were mounted so that they could be assembled into the high-pressure CGSE, which greatly increased their thermal mass. As a result, accurate measurements of gas temperature could not be obtained, preventing validation of the model. However, sufficient pressure, force, and timing data were collected for full characterization of the single-stream thruster. In Figure 5-7, thrust is plotted against two different pressure measurements from the single-stream characterization tests. Figure 5-7. Plots of single-stream thruster output vs. pressure [38]. (a) Thrust vs. regulator output set pressure, measured upstream of shut solenoid valve just before thruster firing. (b) Thrust vs. chamber pressure, measured downstream of open solenoid valve but upstream of nozzle during thruster firing. 80
Figure 5-7 illustrates several aspects of the pressure-thrust relationship that were revealed through single-stream testing. First, there was an approximately linear relationship between thruster output and chamber pressure, as shown in Figure 5-7(b). The maximum thrust attained by the CGSE thruster in the single-stream tests was 40 N, produced with a chamber pressure of 392 psia, and obtained using the flight regulator and flight tanks as shown in the Figure 5-6 configuration. However, comparison between Figure 5-7(a) and Figure 5-7(b) shows that chamber pressure was not the same as the regulator output set pressure, as had been assumed in the MATLAB model. Rather, there were often significant pressure losses incurred, and these losses were strongly affected by feed line geometry. For instance, the choked flow that occurred in the first testing setup (illustrated in Figure 5-3) is clearly visible in Figure 5-7(a), where the Lab Cylinder (Long Line) points level off at approximately 12 N thrust for all regulator output set pressures above 400 psia. This did not occur for either of the other testing configurations. However, the flight tanks and regulator clearly had less pressure loss than the laboratory cylinder and regulator, since the flight setup was able to produce higher levels of thrust at the same regulator output set pressures as the laboratory cylinder setup, even without the long choked feed line. As mentioned before, it was believed that this was due to the low
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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
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: Figure 5-5. CGSE high side as const
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 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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