Development of a Cold Gas Propulsion System for the ... - SSL - MIT
Development of a Cold Gas Propulsion System for the ... - SSL - MIT Development of a Cold Gas Propulsion System for the ... - SSL - MIT
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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6.3.1 Thruster Identification<br />
To track <strong>the</strong> per<strong>for</strong>mance <strong>of</strong> individual thrusters, an identification system involving letters and numbers<br />
was developed. The four corners <strong>of</strong> <strong>the</strong> TALARIS vehicle were designated as A, B, C, and D, and <strong>the</strong><br />
thruster pair nearest to each corner was also identified by that letter. These pairs were called station<br />
pairs. Each individual thruster was also given an identifying number from 1 to 8. All vertical thrusters<br />
had odd numbers, and all horizontal thrusters had even numbers. Numbering proceeded around <strong>the</strong><br />
vehicle from A to D, so <strong>the</strong> vertical thruster in station pair A was thruster 1, <strong>the</strong> horizontal thruster in<br />
station pair A was 2, <strong>the</strong> vertical B thruster was 3, <strong>the</strong> horizontal B thruster was 4, etc., as shown in<br />
Figure 6-6.<br />
Figure 6-6. Identification <strong>of</strong> thrusters by number and letter. Body coordinate axes also shown [38].<br />
6.3.2 Static Test Stand<br />
CGSE thruster per<strong>for</strong>mance in <strong>the</strong> full flight system was measured using a 6-axis load cell, which could<br />
measure <strong>for</strong>ces along three orthogonal axes as well as moments about those axes. For <strong>the</strong>se<br />
measurements to be accurate, <strong>the</strong> TALARIS vehicle had to be entirely supported by <strong>the</strong> load cell with no<br />
90
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