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Detailed Design Review Team Members:Josh Benton Nathan Bialke Sean Bradburn Liana Garbowski Robert Lane Garrett Manfull Presented To:Marc Murbach March 1, 2007
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2 Project Value
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3 SOAREX ► Aligned with SOAREX goals Sub-orbital atmospheric experimentation Innovative method of data gathering Improved understanding of atmospheric data collection without conventional sensors
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4 Future Use Potential ► Atmospheric data collection – other planets Small Relatively inexpensive Expendable ► Mars lander missions Improved landing accuracy through real-time atmospheric data collection
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5 System Overview
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6 ► Atmospheric data collection device Activation: redundant mechanical switching upon ejection Data transmission: radar transponder and radar antenna; data tracked by ground base Thermal protection: spherical Teflon probe body enclosing all components Data extraction: atmospheric properties backed out through software math model
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7 Mechanical Review
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8 Mechanical Overview
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9 Probe Body – Bottom Shell
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10 Probe Body – Bottom Shell
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11 Probe Body – Bottom Shell ► Strengths Concentration of mass ensures probe will fall in a “bottom-first” orientation Single-material construction ► Solves coefficient of expansion problems ► No delamination Teflon advantages ► Highly machinable ► Favorable heating properties
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12 Probe Body – Bottom Shell ► Improvements needed Mass reduction (bottom is ~8 lbs. by itself) Potential heat-related design revisions ► Awaiting completion of heat modeling
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13 Probe Body – Bottom Shell ► Potential failure modes Excess ablation rendering data useless or complete meltdown ► Actions taken: analytical heat modeling, possibly arc-jet testing Separation from upper shell ► Actions taken: Metal Key-sert threaded inserts used to strengthen attachment points
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14 Probe Body – Top Shell
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15 Probe Body – Top Shell
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16 Probe Body – Top Shell ► Strengths “Shelled out” design ensures mass will be significantly less than bottom half of sphere Constructed from Teflon ► Same expansion coefficient as bottom shell ► Same favorable heating properties as bottom shell
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17 Probe Body – Top Shell ► Improvements needed Mass reduction (possibly change to a less-dense material with a similar coefficient of expansion)
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18 Probe Body – Top Shell ► Potential failure modes Heat-related failure, allowing deformation or separation from bottom shell ► Actions taken: “worst-case” heat modeling
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19 Switch Assembly
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20 Switch Assembly
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21 Switch Assembly ► Strengths Activation requires 2 of 3 switches to activate ► Protection from premature single-switch activation ► Protection from single-switch failure Switch operation not reliant on probe orientation in foam Moving parts ejected from probe upon activation
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22 Switch Assembly ► Improvements needed: (Possibly) longer activation plungers and springs to meet 2” extension-before-activation criteria Possible relocation of activation points at different locations on probe body
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23 Switch Assembly ► Potential failure modes Heat-related failure prior to activation ► Actions taken: plunger holes slightly oversized for thermal expansion/contraction Early activation ► Actions taken: redundant switch setup, simple 1- moving-part design, switches locked in fully- depressed position before activation, backing plate to be placed in foam above switch area to prevent foam erosion
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24 Electrical Review
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25 Electrical Overview ► System schematic
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26 Batteries
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27 Batteries ► Strengths Two independent 14.4V lithium ion battery packs, each capable of powering probe Battery controller isolates battery packs
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28 Batteries ► Improvements needed Potential mass reduction, if necessary Size reduction or arrangement reconfiguration
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29 Batteries ► Potential failure modes Battery failure, loss of voltage ► Actions taken: Use of two redundant battery packs; either one can completely power probe Reversed battery polarity ► Actions taken: Battery controller will isolate backwards battery from properly installed battery, which will power probe Failure of electrical connections ► Actions taken: : Connections made with terminal blocks using mechanical compression rather than solder
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30 Batteries ► Potential failure modes, continued Thermal-related failure resulting in explosion or fire from overcharge or over-discharge ► Actions taken: Battery controller prevents overvoltage, undervoltage, and completely isolates two battery packs
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31 Radar Transponder/Antenna
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32 Radar Transponder/Antenna ► Supplied components Problem: The components are not verifiable – UI doesn’t have any mechanisms for testing a radar transponder or antenna Solution: Currently an open issue – will require attention at NASA Ames for verification
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33 Modeling
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34 Heat Model ► Fay-Riddell: ρ, V from Robert’s trajectory model ► To find stagnation point temperature: Can then determine ablation – significant after ~400 degrees C
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35 Heat Model ► Linear Ablation: S – linear ablation ρ ∞ - free stream density R – nose radius V ∞ - free stream velocity
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36 Trajectory Model
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37 Trajectory Model
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38 Trajectory Model
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39 Trajectory Model
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40 Ablation
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41 System Functionality Status
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42 Mechanical Functionality ► Probe body – bottom shell Integration with components functional; awaiting heat modeling to verify design ► Probe body – top shell Status same as bottom shell ► Switch assembly Fully functional and undergoing failure testing
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43 Electrical Functionality ► Batteries Functional and in our possession ► Radar Transponder Awaiting delivery ► Radar Antenna Awaiting delivery
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44 Open Issues
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45 Open Issues ► Weight – too great? Increased ballistic coefficient; increased heating Do we need to change to a different material? ► Modeling not yet complete ► Final design dependent on results of modeling Must withstand heating Must be able to generate useful data
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46 Budget Report
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47 Budget
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48 Battery Controller Schematic
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49 Voltage Regulation Schematic
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