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

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was controlled manually; later, modules were added to the software to allow for sequences of multiple pulses of predefined pulse width and spacing to be launched with a single command. 5.2.2 Laboratory Nitrogen Cylinders Some early single-stream characterization tests were performed by feeding the instrumented thruster from a standard laboratory cylinder of compressed nitrogen, with the pressure controlled by the cylinder regulator. This was done for several reasons. First and foremost, the Tescom regulator meant for the flight system could not easily interface with a laboratory cylinder, so using it essentially required constructing the entire high side of the CGSE as shown in Figure 3-3. It was believed that it would be faster and simpler to run off of a laboratory gas cylinder instead of going through the process of filling up the CGSE flight tanks for every test, especially since even though most laboratory cylinders were filled to pressures less than 4500 psia, they could still hold more nitrogen than the flight tanks. Furthermore, it was known that the flow rates required by a single thruster solenoid valve were far below the full capacity of the flight regulator, so it was believed that single-stream testing would provide relatively little useful information about flight regulator performance, and that useful data could be collected about the CGSE thruster without using the flight regulator. The first setup for collecting single-stream thruster data is shown in Figure 5-3. Figure 5-3. First configuration for single-stream characterization tests. 76
As indicated in Figure 5-3, initial CGSE tests were conducted inside a blast chamber until a better sense of safety around the CGSE was developed. In the first single-stream testing configuration, the laboratory nitrogen cylinder which fed the thruster was located outside the blast chamber, for easy access by operators of the CGSE. However, a very long tube of relatively small diameter (0.375 in. OD, 0.277 in. ID) was used to feed the gas to the thruster, and this made the system prone to choking as described in the next section (see especially Figure 5-7(a)). As a result, the setup was revised to remove the long feed tube. The laboratory nitrogen cylinder was moved inside the blast chamber, near enough to the instrumented thruster that the flex tube could be connected directly to the cylinder regulator as shown in Figure 5-4. Figure 5-4. Second configuration for single-stream characterization tests. The setup shown in Figure 5-4 did not produce the dramatic choking effects observed in the first configuration, but the thruster still did not perform as well as anticipated with this setup. The laboratory cylinder regulator had to be set to an output pressure of over 1000 psia to produce the 30 N of thrust required for the CGSE, and the flight regulator was not capable of having an output pressure that high. However, upon investigation, it was discovered that the laboratory cylinder regulator had a
Page 1:
Development of a Cold Gas Propulsio
Page 5:
Abstract The TALARIS (Terrestrial A
Page 9 and 10:
Table of Contents List of Figures .
Page 11:
7 Ongoing and Future Work .........
Page 14 and 15:
Figure 6-6. Identification of thrus
Page 17 and 18:
Notation Acronyms and Abbreviations
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N newton Pa pascal psi pounds per s
Page 21 and 22:
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: the solenoid valve, and a pressure
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 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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