1. Introduction and Overview Mechanical Design Integration Peer Review, March 2003 1. Introduction and Overview Martin Nordby nordby@slac.stanford.edu 24 March 2003 rev 1

1. Introduction & Overview Mechanical Design Engineering Organization Mechanical Design Overview LAT layout and interface definitions System block diagram Design details Design changes since Delta PDR CCB’s: approved since Delta PDR and pending

Review Material All presentation material and documentation is available on the web at: http://www-glast.slac.stanford.edu/MechanicalSystems/Meetings&Talks/2003-03-DesignIntCDR/DesignIntCDR.htm Hard copies of all presentation material are reproduced in the binders available to reviewers Hard copies of all documentation, back-up material, drawings, and reports are available for review

Mechanical Design Engineering Organization LAT Organization Since Delta PDR, LAT engineering organization and responsibilities have changed Instrument Design Engineering group added LAT Chief Engineer: Lowell Klaisner Responsible for design integration, systems analysis, and fabrication planning for the LAT Works with Systems Engineering to manage LAT interfaces and resolve interface and internal subsystem design issues 4.1.8 Mechanical Systems subsystem re-scoped to focus on flight hardware development, fabrication, and testing Work Breakdown Mechanical Design Integration Part of Chief Engineer’s Design Engineering group Interface design and development within and external to the LAT Managing of LAT mechanical metrics: mass, dimensions, dissipated power LAT structural and thermal analysis Performing LAT-level design and trade studies Flow-down of environmental and test parameters to LAT subsystems LAT environmental test planning and technical management 4.1.8 Mechanical Systems Design and development of Grid Box, Radiators, and heat pipes from subsystem requirements flowed down from LAT Fabrication and verification testing of subsystem hardware and delivery to I&T group Peer Reviews will follow this work breakdown Mechanical Design Integration Peer Review: 26 Mar 2003 Mechanical Systems Peer Review: 27 Mar 2003

Mechanical Design Overview LAT Structural Design Parameters Design Spec Mass 2679.4 kg <3000 kg Center of Gravity 149.3 mm <185 mm Width 1806 mm <1820 mm Height 1081.5 mm 1100 mm Tracker (TKR) Mass 504.9 kg (Mar 2003 est) Size 372 mm sq x 640 h Interfaces Grid Ti flexure mount and Cu strap Calorimeter (CAL) Mass 1375.8 kg (Mar 2003 est) Size 364 mm sq x 224 mm h Interfaces Grid bolted friction joint Anticoincidence Detector (ACD) Mass 270.1 kg (Mar 2003 est) Size 1806 mm w x 1081.5 mm h Interfaces Grid bolted joint, shear pins Grid/X-LAT Plate/Radiators Mass 329.3 kg (Mar 2003 est) Size 1580 mm sq x 236 mm h Interfaces Four-point mount to SC flexures LAT Mass Budget and Current Estimates (kg) Estimate Budget TKR 504.9 510.0 CAL 1375.8 1440.0 ACD 270.1 280.0 Mech 329.3 345.0 Elec 199.3 220.0 LAT Total 2679.4 3000 Source: LAT-TD-00564-6 “LAT Mass Status Report Mass Estimates for Mar 2003” Electronics Mass 199.3 kg (Mar 2003 est) Size 1417 mm sq x 222 mm h Interfaces Stand-off to CAL; thermal joint to X-LAT Plate LAT Overview

System Block Diagram LAT Block Diagram MLI Surrounding ACD ACD Base Elec Ass’y alum frame TKR Module CFC tray, side walls Grid monolithic alum structure Spacecraft LAT mounting structure Spacecraft SC bus structure CAL Modules alum bottom plate Solar Arrays S.A. mount Elec. Boxes alum electronics box EMI Skirt Shields E-Boxes, supports X-LAT Pl Radiator Mnt Bkt Support Radiators at corners of Grid LAT Radiators on +/- Y sides of LAT Grid X-LAT Plate monolithic alum structure Htr Switch Boxes Operate Radiator heaters MLI Insulation MLI surrounding underside of LAT LAT Block Diagram

LAT Design Details Radiator Mount at Grid corners. Note mid-side Grid Wing Grid corner detail showing heat pipes, purge grooves; corner chamfer and bottom flange for ACD Copper thermal straps Reverse-angle view of VCHP S-bends and DSHP connection TKR mid-side and corner flexures

LAT Interface Details Grid Wing with SC mount bracket EMI Skirt cut-outs around SC stay-clear SC proposed interface stay-clear on top of octagonal SC volume PAF, per Boeing PPG LAT inside LV fairing static stay-clear

LAT Underside Design Details Empty boxes GASU box SIU boxes Upside-down view of a Grid Y mid-side, showing DSHP’s, Grid Wing, and EMI Skirt PDU box TPS (16x) EPU boxes TEM (16x) LAT Underside View of Electronics Boxes Detail of TEM, TPS, and EPU box stack

Design Changes Since Delta-PDR Subsystem changes affecting system performance TKR bottom tray re-work: strengthens CC tray in high-stress corner regions TKR flexure re-design: accommodates updated bottom tray design and provides for stiffer cantilever mode for TKR ACD mass growth: accommodates larger tile overlaps and increase in structural stiffness and strength Interface changes Wing bracket: re-designed to include vertical SC mount bracket hanging under Grid TKR thermal straps: copper straps provide compliant joint to Grid E-box mounting to CAL plate: E-boxes hard-mounted to CAL back plates now X-LAT plate thermal connection: V-Therm cloth CAL-Grid friction joint questioned by GSFC: currently investigating discussion

Design Changes Since Delta PDR (cont) VCHP S-bends SC-LAT mount region still in work Radiator panels widened and shortened, reducing thermal efficiency Panels cut-out locations fixed LAT Delta PDR Design July 2002 LAT CDR Design Mar 2003

Change Control Board Changes Since Delta-PDR ACD mass growth Added structural mass to increase design margins Added mass in scintillating tiles to increase size of tiles and overlap between tiles Mechanical Systems mass growth Added mass for Grid box additions: Grid Wing, bottom flange, EMI Skirt stiffening, X-LAT thermal straps Added mass for slightly increased Radiator area Calorimeter mass de-allocation Decreased mass allocation to reflect reduction in size of CsI logs Log size was reduced to accommodate tolerance stack-up within CFC box structure Power allocation update (pending) Updated power allocations based on current measured values Already using updated allocations in thermal analysis