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SKA TDP & CART 15m (DVA-1) ANTENNA DESIGN 11

SKA TDP & CART 15m (DVA-1) ANTENNA DESIGN 11. US SKA Consortium Meeting at Arlington VA June 3-4, 2010 Matt Fleming. Contributions from Jack Welch Roger Schultz Gordon Lacy Lynn Baker German. Antenna Design Drivers. Must achieve survival. ( 100 mph wind )

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SKA TDP & CART 15m (DVA-1) ANTENNA DESIGN 11

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  1. SKA TDP & CART 15m(DVA-1) ANTENNA DESIGN 11 US SKA Consortium Meeting at Arlington VA June 3-4, 2010 Matt Fleming Contributions from Jack Welch Roger Schultz Gordon Lacy Lynn Baker German

  2. Antenna Design Drivers • Must achieve survival. • ( 100 mph wind ) • 2 Low cost per unit area of aperture. ( good sky coverage ) ( installed ) • ( low cost materials, low mass design, low fabrication labor ) ( favors symmetric ) • 3 Very low operational cost for a 30 year life • ( very few maintenance visits required ) • 4 Frequency range of 0.3 to 10 GHz with WBSPF • ( 4.0m Gregorian secondary ) ( favors offset ) • 5 Excellent Ae / Tsys. • ( accurate surfaces, controlled spillover, low diffraction ) ( favors offset ) • 6 Exceptional dynamic range. • ( very rigid surfaces, very good pointing, ) pt source sensitivity survey survey speed Performance vs Cost Tradeoffs These will shape specifications. US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 2 of 28

  3. Basic fabrication cost drivers Design Driver 2, Cost • Raw material costs. ( fairly constant world wide )( a good design is light weight ) • Labor cost. ( varies by type and location based on economic and social conditions ) For some designs material is often traded for labor Technology. ( application of intellect to use of material, labor & energy ) Number of units needed. ( investment in tooling ) Transportation. ( where made, where assembled, where installed ) Remote fabrication of smaller elements allows use of global labor competition. Understanding these items for every design allows engineering shortcuts We cannot do detailed design on every possible design approach US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 3 of 28

  4. What is New • We have an aperture diameter specified at 15m. • We will maintain the offset high configuration for now. • We have a new approach for the primary reflector. (CART) • We have better relative cost info from 12m for tradeoff decisions. • We have a better understanding system operations cost. (SPDO) • We have a well defined shaped optics design. • We have new specifications. US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 4 of 28

  5. Preliminary Specifications 1 of 2 Slide for reference & questions US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 5 of 28

  6. Preliminary Specifications 2 of 2 Slide for reference & questions US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 6 of 28

  7. Single shell or stressed skin • Single piece reflectors often have low labor cost relative to alternate designs. • Reflector edge support by itself preserves accuracy extremely well. • The reflector surface can act as the structural front side of a deeper system. • Rim edge and center support works better if the center has axial flexibility. • The concept can work for symmetric or offset designs. Primary as a monocoque element Jump to single shell On Az-El mount US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 7 of 28

  8. ATA 6.1m Implementation • A frame & spar system gives good edge & center support with an open center. • Wind & gravity moment loads are reduce with Az & El near the shell center. • The support system allows a compact turret head to be nested close to shell. • A compact turret head can contain almost all the precision machining needs. • A relatively simple pipe pedestal can support the turret head. ( wind & thermal ) US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 8 of 28

  9. Center frame 16 members The TDP 15m Implementation Spars 13 members Secondary & feed support 22 members Materials & sections can be adjusted Preliminary Weight Est ( Kg ) Total Secondary Assy Total Primary Assy Total on El Bearing Total on Az bearing Total Turret Flange Total Antenna 2,400 4,950 7,350 10,050 10,250 14,450 US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 9 of 28

  10. Hydroforming Big Reflectors • Hydroforming has low production cost and is a fast process. • Hydroforming a 12m symmetric is considered quite possible at 3mm thickness. • Hydorforming a 15m x 18m offset is definitely more difficult to predict. • Manufacturing repeatability is better with thickness, worse with flatness. • Plastic deformation FEA is needed to predict 15m repeatiblility. ( Ohio State ) • Tooling will be very expensive. ( 12m was considered to be 2M$ ) (DVA-1) US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 10 of 28

  11. Canada DRAO CART Project and South Africa MeerKAT Project have generated cost and performance information for composite on site reflector fabrication. Information from Composite Investigations Prototype 10m complete. Symmetric with Core, Beams & Hub. SKA Memo 116 costing information Starting to investigate Offset monocoque V3 DRAO = Dominion Radio Observatory CART = Composite Application Radio Telescope US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 11 of 28

  12. Both hydroformed metal and fiber reinforced plastic create good monocoque structures HM & FRP shells are similar FRP can replace HM reflectors and can provide edge support Rim beam & spars favored over shell support US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 12 of 28

  13. Additional Views US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 13 of 28

  14. Feeds Beam Path Close approximation of TDP shaped optics design US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 14 of 28

  15. Structural Simplicity More about PAF position later Triangular deep trusses good Cured beams and curved shells bad Tubular structures are very efficient at handling bending and torsion US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 15 of 28

  16. Secondary & Feed Support Light weight structure 180 Kg Heavier structure US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 16 of 28

  17. TDP & CART Team Collaboration Matt Fleming beginning to analyze and detail 15m mount and drive systems Gordon Lacy is beginning to run FEA optimizations on reflectors & supports US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 17 of 28

  18. Deliverable Antenna Elements Secondary Primary not shown It is an on site fabrication Feed and indexer Primary center frame Secondary and feed support Electronics enclosures Pedestal Turret head US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 18 of 28

  19. Pedestal Fabrication Machined Flange Consider use of ring forgings Alternate foundation concepts are still under consideration US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 19 of 28

  20. Turret Head Assembly Deliverable Assembly Includes az drives, bearings, encoders, electronics US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 20 of 28

  21. Primary Center Frame Pentagonal frame shown Tubes all have parallel end cuts Machining of this portion may be necessary and a little expensive US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 21 of 28

  22. Turret Head & Az drives Deliverable Assy Machined fabrication Double row ang contact, Or crossed roller, or 4 pt, With oil bath Az drive modules Lubrication 60 months US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 22 of 28

  23. Azimuth Drives Dual idler supported pinion Multiple modular drives Access to drives RFI control Full oil bath lubrication for 60 month period US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 23 of 28

  24. Currently envision a custom actuator El Bearings & El drive Gravity loading helpful. Low clearance important Bearing choices tuff. US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 24 of 28

  25. Encoders & Pointing Both encoders can be interior to the turret head allowing environmental protection and easy cabling. Unatainium box on back of dish is the best option Long light weight tube might be problematic Limit switch gearing Addition of tilt meter and accelerometer devices will enhance performance Attachment to reflector surface away from loaded areas Az tube could extend to ground for higher accuracy, but ……. US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 25 of 28

  26. ATA in glass PAF shown 1m x 1m x 1m Feeds & Indexer & PAF Lindgren in can Pivot & structural support PAF at secondary focus still under consideration Space for PAF implies two leg support frame US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 26 of 28

  27. Feed Indexer Concepts linear slide. sector type. turret type. Consider cable wraps, precision, access, dirt. Position repeat to 1.0mm. Quick release fast exchange for feeds. US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 27 of 28

  28. Questions End US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 28 of 28

  29. HMR monocoque appears to perform well 12m Computed RMS 0.008 inches 0.20 mm Preliminary US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 29 of 28

  30. 12m Computed RMS 0.013 inches 0.33 mm Preliminary US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 30 of 28

  31. 12m Computed RMS 0.001 inches 0.03 mm Preliminary US SKA Consortium, Arlington, 2010-06-04 Matt Fleming slide 31 of 28

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