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RBSP Spacecraft Mechanical Accommodations for the EFW Rigid Whip Axial Boom design

RBSP Spacecraft Mechanical Accommodations for the EFW Rigid Whip Axial Boom design. Jeff Kelley Mechanical Design Engineer Comments by Paul Turin, SSL in green. Baseline EFW Axial Boom (AXB) design. Baseline – Information taken Kick-Off meeting (Oct. 2006) – THEMIS Design.

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RBSP Spacecraft Mechanical Accommodations for the EFW Rigid Whip Axial Boom design

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  1. RBSP Spacecraft Mechanical Accommodationsfor the EFW Rigid WhipAxial Boom design Jeff Kelley Mechanical Design Engineer Comments by Paul Turin, SSL in green

  2. Baseline EFW Axial Boom (AXB) design • Baseline – Information taken Kick-Off meeting (Oct. 2006) – THEMIS Design • Mass: 4 kg total (2 booms + tube). • Footprint: 41H x 5 to 6 OD inches. • Deployed Length: • 12 to 13 m tip-to-tip. • 1-m whip sensor stacer. Power: 35 W max for 1-2 s, per boom (deploy only). • Actuators: deploy is spring-driven, Frangibolt-released; no pyros required for deploy. Radiation Belt Storm Probe

  3. UCB Updates to Baseline Design: • AXB CBE 3.12kg ea. (not incl. tube) – longer stacer, motor drive, 3-stage DAD • Footprint: 6” dia. x ~32”(min) for two booms • 12m tip-to-tip at max extension • 0.44m (17.25”) whip/sphere length • Power 35W@34V, duration ~10-30sec @23C • Power and time vary with voltage and ambient temp • Two actuators per boom – one for whip, one for stacer caging Radiation Belt Storm Probe

  4. 174.2m[6.86in] 253.99mm [10.00in] Ø87.63mm[34.50in] 164.76mm [6.49in] 324.54mm [12.77in] S/A FWD Deck 5.87mm [2.31in] EFW Baseline AXB and Antenna, stowed • RF-Antenna Requirements: Stowed • Provides communication • immediately after payload • separation Radiation Belt Storm Probe

  5. 203.2mm [8.00in] 627.4mm [24.70in] 508.0mm [20.00in] 50.0° EFW Baseline AXB (DAD envelope shown)and Antenna, deployed • RF Antenna Requirements: Deployed Radiation Belt Storm Probe

  6. Integration of EFW “rigid whip” AXB design into Spacecraft Model Axial Boom with “whip” added to S/C Model (AFT RF-Antenna not shown) STEP file from EFW Radiation Belt Storm Probe

  7. Comments on new “rigid whip” design • No major issues seen, from the spacecraft mechanical perspective. • Thermal has not had a chance to comment • We request some freedom in selecting where to mount the rigid whip deployment device: • You have the “clamshell” shown attaching to the central cylinder. • Attaching the “clamshell” to the center honeycomb deck, rather than to the cylinder, would allow for better modularity and less stress on the stowed whip. • This is fine -- particularly if boom spacing is decreased, decreasing req’d standoff from decks and resulting clamshell tower height. • Loads in 1/8” dia. whip are a concern – extending clamshell to center tube to carry lateral loads may be prudent. This would also allow full-length cover for I&T protection. • Attaching the clamshell to deck will allow slightly longer whip Radiation Belt Storm Probe

  8. EFW Axial Boom with rigid whip:Canister length reduction? • Question: Can the Canister height (& DAD envelope) be reduced? • >$1M cost savings and risk reduction, if so. • Based on the model that we received, there is empty space in the canister and the entire DAD “envelope” is not needed. • Is all hardware present and accurate in the model? • Assumptions for Axial boom canister: • Lowering FWD and AFT axial boom 0.15m[6.0in] • Reduced canister to: ø0.15m[6.0in] x 0.74m[29.0in] • Able to mount clam-shell for sensor (sphere) to • inner deck rather than cylinder • Fixed RF antenna on mast would be centered as pictured • on previous slide Radiation Belt Storm Probe

  9. Canister Length Reduction • Current design is 17” long stowed (not including clamshell at side)– potential reduction of height above deck of 7” per boom, more if motors overlap. • New triple DAD stroke is 16.25” • Will send updated version of assy to Stuart shortly 16.25” 17” Radiation Belt Storm Probe

  10. 0.20m [8.0in] 0.254m [10.0in] Shortened AXB Canister length implications: Fixed antenna becomes possible Stowed Axial Boom and rigid “whip” (with stowed antenna) Deployed Axial Boom and rigid “whip” (with stowed antenna) Radiation Belt Storm Probe

  11. Shortened Canister Cont. 6.1” 19.0” 59.75” 31.7” Radiation Belt Storm Probe

  12. 12.00m[472.4in] 13.80m[543.3in] EFW AXB rigid whip – length of boom • Currently in S/C design: 12 meters from centerline of sphere to centerline of sphere • New rigid whip STEP file geometry shows a length of 13.8 meters • If both canister and boom are reduced in length, then the reduction of 0.3m [12.0in] overall would still be above 13 meters • Boom models will not be trimmed until final position in tube set. Deployed length will be 11 to 12m (adjustable on orbit) tip-to-tip. Radiation Belt Storm Probe

  13. Additional Items • Small diameter whip will probably require something like 45 deg overtravel to limit bending stresses during flip-up • We could save ~1kg by eliminating AXB tube. Since S/C already has central structural tube, why duplicate? • Would require Tube ID to be close tolerance, circular, smooth and clear of fasteners etc. (or change in mounting scheme) • Tube ID would set position and angle of AXBs (defining S/C geometric axis) • Access required for AXB fasteners (or change in mounting scheme) Radiation Belt Storm Probe

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