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Alex Ordway 60 hours worked

Alex Ordway 60 hours worked. Attitude Control Subsystem Component Selection and Analysis. Design Drivers. Meeting mission pointing requirements Meet power requirements Meet mass requirements Cost Miscellaneous Factors. Trade Study. Sliding Mass vs. Tip Thruster Configuration

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Alex Ordway 60 hours worked

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  1. Alex Ordway60 hours worked Attitude Control Subsystem Component Selection and Analysis

  2. Design Drivers • Meeting mission pointing requirements • Meet power requirements • Meet mass requirements • Cost • Miscellaneous Factors

  3. Trade Study • Sliding Mass vs. Tip Thruster Configuration • Idea behind sliding mass

  4. Trade Study • Sliding mass ACS offers • Low power consumption (24 W) • Reasonable mass (40 kg) • Low complexity • Smaller contribution to spacecraft MOI • Limitations • Unknown torque provided until calculations are made • No roll capability • Initially decided to use combination of sliding mass and tip thrusters

  5. ADCS System Overview • ADS • Goodrich HD1003 Star Tracker primary • Bradford Aerospace Sun Sensor secondary • ACS • Four 10 kg sliding masses primary • Driven by four Empire Magnetics CYVX-U21 motors • Three Honeywell HR14 reaction wheels secondary • Six Bradford Aero micro thrusters secondary • Dissipate residual momentum after sail release

  6. ADS • Primary • Decision to use star tracker • Accuracy • Do not need slew rate afforded by other systems • Goodrich HD1003 star tracker • 2 arc-sec pitch/yaw accuracy • 3.85 kg • 10 W power draw • -30°C - + 65 °C operational temp. range • $1M • Not Chosen: Terma Space HE-5AS star tracker • Lower thermal thresholds (-20°C - +40°C) • Greater power draw (15W)

  7. ADS • Secondary • Two Bradford Aerospace sun sensors • Backup system; performance not as crucial • Sensor located on opposite sides of craft • 0.365 kg each • 0.2 W each • -80°C - +90°C

  8. ACS • Sliding mass system • Why four masses? • FRONTAL PICTURE OF THINGAMAJIG HERE

  9. ACS • Sliding mass system • Four Empire Magnetics CYVX-U21 Step Motors • Cryo/space rated • 1.5 kg each • 28 W power draw each • 200°C • $55 K each • 42.4 N-cm torque

  10. ACS • Gear matching- load inertia decreases by the gear ratio squared. Show that this system does not need to be geared.

  11. ACS • Three Honeywell HR14 reaction wheels • Mission application • Specifications • 7.5 kg each • 66 W power draw each (at full speed) • -30ºC - +70ºC • 0.2 N-m torque • $200K each • Not selected • Honeywell HR04 • Bradford Aerospace W18

  12. ACS • Six Bradford micro thrusters • 0.4 kg each • 4.5 W power draw each • -30ºC - + 60ºC • 2000 N thrust • Supplied through N2 tank

  13. Attitude Control • Conclusion • Robust ADCS • Meets and exceeds mission requirements • Marriage of simplicity and effectiveness • Redundancies against the unexpected

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