Transcript
LBT PROJECT 2x8,4m TELESCOPE Doc.No. : 570s002 Issue :b Date : 17 Dec 2007
LBT PROJECT 2 X 8,4m OPTICAL TELESCOPE
Primary Mirror Cover Assembly Functional and Technical Specifications
Prepared Reviewed Approved
Signature Date Robert Meeks 17 Dec 2007 John Little, Mike Gusick, James Howard, Piero Salinari, Dave Ashby, John Hill Joar Brynnel
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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1. Revision History
Issue A B
Date 7-Sep-06 17-Dec-07
Changes First draft Revised based on comments
Responsible Robert Meeks Robert Meeks
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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2. Table Of Contents 1. 2. 3. 4. 5. 6.
Revision History ......................................................................................................... 2 Table Of Contents ....................................................................................................... 3 Applicable Documents................................................................................................ 4 Purpose........................................................................................................................ 4 Overview..................................................................................................................... 4 Interfaces..................................................................................................................... 4 6.1. Mechanical Interfaces ......................................................................................... 4 6.2. Electrical and Control Interfaces ........................................................................ 4 6.3. Emergency Stop Circuit...................................................................................... 4 7. Operating Conditions .................................................................................................. 5 7.1. Environmental Conditions .................................................................................. 5 7.2. Acceleration, Velocity, and Orientation limits ................................................... 5 8. Functional Requirements ............................................................................................ 5 8.1. Protect Mirror from Impact Damage .................................................................. 5 8.2. Mitigate Dust Contamination.............................................................................. 6 8.3. Stowage for Observing ....................................................................................... 6 8.4. Deploying for Protection..................................................................................... 6 9. Technical Requirements.............................................................................................. 6 9.1. Mass .................................................................................................................... 6 9.2. Resonant Frequency............................................................................................ 6 9.2.1. Stowed......................................................................................................... 6 9.2.2. Deployed ..................................................................................................... 6 9.3. Stiffness and Deflections .................................................................................... 6 9.4. Stowing and Deploying Operations .................................................................... 6 10. Additional Requirements ........................................................................................ 7 10.1. Safety .............................................................................................................. 7 10.2. Design Margins............................................................................................... 7 10.3. Reliability........................................................................................................ 7 10.4. Maintainability................................................................................................ 7 10.5. Access ............................................................................................................. 7 10.6. Failure Modes ................................................................................................. 7 10.7. Emergency Stop .............................................................................................. 7 10.8. Assembly and Installation............................................................................... 7 11. Desired Functions ................................................................................................... 8 11.1. Provide Thermal Insulation............................................................................. 8 11.2. Stowage or Deployment.................................................................................. 8 12. Verification ............................................................................................................. 8 13. Documentation........................................................................................................ 8
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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3. Applicable Documents [RD 1] [RD 2] [RD 3] [RD 4]
002s004g 561s003c 570s001a 570s001a
Telescope Specifications for the Large Binocular Telescope Elevation Utilities Electrical Power Supply Requirements Mirror Cover Control by PLC Mirror Cover Control, Technical Requirements
4. Purpose The purpose of this document is to outline and specify the design requirements for the LBT primary mirror cover assemblies. The scope of this specification includes primary mirror cover mechanical assemblies as well as the associated control system. 5. Overview The two 8.4 meter primary mirrors of the LBT must be protected from damage and contamination when the telescope is not in use. They must also be maintained at a homogeneous temperature. The primary mirror cover assemblies protect the mirrors from contamination and damage and reduce ventilation or solar radiation of the mirror surface to mitigate temperature gradients through the mirror. 6. Interfaces 6.1. Mechanical Interfaces There are several possible locations where the primary mirror cover assemblies may be attached to the telescope or enclosure. The mirror cover assembly must interface with the telescope or enclosure in such a way that it does not interfere with operation or maintenance. This includes, at a minimum, providing adequate clearance for the bell jar 6.2. Electrical and Control Interfaces The power available to the primary mirror cover assemblies is 208 V, 3-phase, 20 A [RD 2]. Power connections are available at an interface panel located near the upper treehouses on the elevation mount. The primary mirror cover assemblies controller shall interface to an Allen Bradley ControlLogix PLC. A description of this interface and the control strategy is contained in RD3 and RD4. An existing control system developed for an existing mirror cover is available. If the mirror cover assembly is designed to attach to the enclosure, similar power connection will be made available. 6.3. Emergency Stop Circuit The primary mirror cover shall interface to the emergency stop circuit.
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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7. Operating Conditions 7.1. Environmental Conditions The environmental specifications are as follows [RD1]: Storage Temperature Operating Temperature Storage Pressure Operating Pressure Storage Humidity Operating Humidity Wind speed (while stowed or deployed) Wind speed (during stow or deploy operation) Wind speed (survival, deployed) All Surface Temperatures (observing)
-30 to +50 ºC -20 to +25 ºC 500 to 760 Torr 500 to 600 Torr 5 to 95% 5 to 95% < 60 mph < 20 mph < 100 mph TA-1 ºC to TA+1 ºC
7.2. Acceleration, Velocity, and Orientation limits The primary mirror cover assembly must withstand the following azimuth acceleration and velocity limits both in the deployed (covering the mirror) and stowed (uncovered) configurations [RD 1]. If the mirror covered is designed to be useable away from zenith it must withstand these motions in any orientation within its allowable use limits. Angular Velocity Angular Acceleration
1.5 degrees/second 0.3 degrees/second2
8. Functional Requirements The primary mirror cover assemblies perform three functions on the telescope: protecting the mirror from damage during maintenance, mitigating dust contamination, and providing thermal protection to maintain uniform mirror temperatures. The covers must be capable of being automatically stowed for observing and deployed into position to protect the mirrors when the telescope is not in use. Requirements for performing each of these functions are described below. 8.1. Protect Mirror from Impact Damage Hand and power tools, cranes, and other equipment must be occasionally used around the mirrors for routine preventive and corrective maintenance. While safety devices and careful procedures are used during these operations, the mirror cover assemblies must protect the mirror from items dropped accidentally or as a result of equipment failure. The requirements of this section describe a hypothetical occurrence of a dropped object that the mirror covers must minimally protect against. This is the minimum impact resistance the mirror covers must provide. Greater protection is highly desirable.
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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The primary mirror cover shall prevent damage to the mirror if a bluntly-shaped 1 kg mass is dropped from a height of 5 meters onto the cover when it is deployed over a mirror. It is acceptable for the mirror cover itself to be damaged and require repair as a result of such an event. 8.2. Mitigate Dust Contamination The primary mirror cover shall mitigate dust contamination of the surface of the primary mirror. This is a qualitative requirement that is not intended to be quantified or measured. 8.3. Stowage for Observing The primary mirror cover assemblies shall fold or otherwise move out of the way when the telescope is used for observation. There are several possible locations where the covers may be stowed. 8.4. Deploying for Protection The primary mirror cover assemblies deploy into position to protect the mirrors when the telescope is not used for observing. 9. Technical Requirements 9.1. Mass The mass of the primary mirror cover shall not exceed 5000 kg. 9.2. Resonant Frequency 9.2.1. Stowed The lowest natural resonant frequency of the primary mirror cover assembly when stowed shall not be less than 10 Hz. 9.2.2. Deployed The lowest natural resonant frequency of the primary mirror cover assembly when deployed shall not be less than 5 Hz. 9.3. Stiffness and Deflections The location of the primary mirror cover assembly near the primary mirror optical surface requires that it be stiff enough to resist deflection that may bring it into contact with the primary mirror surface or other equipment. 9.4. Stowing and Deploying Operations Stowage must be completed automatically without human intervention and must be completed within 10 minutes.
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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Stowing or deploying the primary mirror cover assembly shall be possible with the telescope stationary at zenith. 10. Additional Requirements 10.1. Safety Operation and maintenance of the primary mirror cover assemblies shall present no hazards to equipment or personnel. 10.2. Design Margins All structures and mechanisms shall be designed with minimum factor of safety of 4 against static failure. 10.3. Reliability The MTBF for each primary mirror cover assembly shall be no less than 10,000 deploy/stow cycles with a goal of 50,000. 10.4. Maintainability Routine maintenance of the primary mirror cover assemblies shall require less than 8 hours annually using a team of two skilled technicians. 10.5. Access When the primary mirror assembly is deployed it must not restrict access to the bent Gregorian instrument stations, tertiary mirror assembly, prime focus assembly, or other key areas of the telescope requiring routine maintenance. When the primary mirror assembly is stowed it must not restrict installation of the coating bell jar onto the telescope. 10.6. Failure Modes Failure of any mechanical component shall not compromise the safety of the primary mirror assembly. 10.7. Emergency Stop The emergency stop (EStop) circuit is a fail-safe fiber-optic circuit to which all motion control subsystems must respond. The primary mirror assemblies shall respond to an EStop condition by de-energizing the drive power supplies and applying brakes to stop all motion. Recovery from an EStop condition shall require manually resetting using a local reset button. No part of the EStop system shall rely on software to function. 10.8. Assembly and Installation
LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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The primary mirror assemblies shall include all lifting points and specialized fixtures required to assemble and install the assemblies on the telescope without removing significant parts of the telescope, in particular the M3 swing arm or M3 unit. 11. Desired Functions The functions described in this section are considered desirable if they can be achieved without sacrificing the required performance specified elsewhere in this document. 11.1. Provide Thermal Insulation The primary mirror cover should insulate the mirror and provide thermal resistance equivalent to R3. In addition, the external service should be painted to reject solar radiation. 11.2. Stowage or Deployment The ability to stow or deploy the mirror cover at any elevation angle within the range of motion is desirable. 12. Verification All requirements of this specification shall be verified by appropriate analysis, measurement, inspection, or demonstration. 13. Documentation The following documentation shall be delivered with the primary mirror cover assembly equipment. • • • • • • • • • • • • •
Electrical and mechanical design documents Component and assembly drawings Schematics Bill of materials list Spare parts lists Finite element analysis reports Finite element models (electronic format) Test procedures Assembly procedures Installation procedures Operating manual Maintenance procedures Inspection and test documentation demonstrating compliance with these specifications
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LBT PROJECT Primary Mirror Cover Assembly Functional and Technical Specifications
Doc.No : 570s002 Issue : b Date : 17-Dec-07
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Doc_info_start Title: Primary Mirror Cover Assembly, Functional and Technical Specifications Document Type: Specification Source: Steward Observatory Issued by: Robert Meeks Date_of_Issue: 17 Dec 2007 Revised by: Date_of_Revision: Checked by: Date_of_Check: Accepted by: Date_of_Acceptance: Released by: Date_of_Release: File Type: MS Word Local Name: Primary Mirror Cover Assembly, Functional and Technical Specifications Category: 500 Telescope Elevation Mount Sub-Category: 570 Mirror Covers Assembly: 570 Mirror Covers Assembly Sub-Assembly: Part Name: CAN Designation: 570s002 Revision: b Doc_info_end
