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

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from the higher specific impulse when total impulse requirements are low. Figure 2-7 illustrates this relationship between system mass and total impulse. Figure 2-7. Weight/mass of propulsion systems vs. total impulse delivered [24]. The relationship illustrated in Figure 2-7 is reinforced by consideration of the lander testbeds discussed in section 2.1. The large vehicles that competed in the Northrop Grumman Lunar Lander Challenge used bipropellant propulsion because those systems can deliver the large amount of impulse needed with the lowest mass possible. By contrast, the smaller vehicles like the ACAT lander and the NASA test vehicles used monopropellant and cold gas propulsion, since those systems have better performance in the lighter weight range. The design of the GLXP hopper, including size and impulse requirements, has not yet been finalized, although monopropellant hydrazine has been suggested for its propulsion system [17]. But all three types of propulsion systems under consideration behave similarly – they all control thrust by varying propellant flow, and all can be designed to have a pulsed operation mode for attitude control – so the TALARIS hopper should be able to provide an accurate simulation of the GLXP hopper regardless of the particular rocket propulsion system chosen for each vehicle. 32
2.3.2 Comparison of Cold Gas and Monopropellant Systems Mass was used as an initial guide for propulsion system type selection for the TALARIS hopper. As mentioned earlier, the 16.898 class in fall 2008 developed an initial conceptual design for a spacecraft emulator propulsion system using nitrogen cold gas propellant; the estimated mass of this system was 17 to 20 kg (37.5 to 44.1 lbs) [25]. However, after evolving the design of the rest of the TALARIS vehicle, the 16.83/89 class in spring 2009 recommended reducing the mass of the cold gas system to 10 kg (22.0 lbs) [26]. As shown in Figure 2-7, these masses are in the range where the most efficient propulsion system type in terms of highest total impulse for lowest system mass begins to transition from cold gas to monopropellant. Thus, it was decided to examine in depth whether a monopropellant system might be a better choice than cold gas for the TALARIS spacecraft emulator propulsion system. Monopropellant systems can offer a significant improvement in specific impulse (
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
Page 19 and 20: 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: Ballistic hops tend to use less pro
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
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6 Full Eight-Thruster Flight System
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Figure 6-2. TALARIS CGSE assembled
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stream tests revealed that changes
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Figure 6-5. Original CGSE control c
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other constraints. This was difficu
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variables (such as number of thrust
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One solution to this problem would
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One of the characterization tests w
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or more thrusters were firing toget
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Table 6-3. Valve timing metrics dur
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Figure 6-11. Redesigned CGSE contro
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The imaginary simplified thruster c
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traverse phase of a hop and involve
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Figure 7-3. GNC data from 3-DOF tes
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Tests on this vertical stand demons
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control the belay line can be put u
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accounting for changes in thrust le
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development under the supervision o
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documenting progress takes time whi
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were encountered, it was harder to
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[10] Bryant, K. M., Knight, C. J.,
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[31] Canadian Centre for Occupation
Page 129 and 130:
[50] ISA - The Instrumentation, Sys
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Development of a Cold Gas Propulsion System for the ... - SSL - MIT

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